,transcriber's ,notes3 ,underscores 80 before and after a word or phrase indicate italics in the original text4 ,small capitals have been converted to ,,solid capitals4 ,illustrations have been moved so they do not break up paragraphs4 ,old or antiquated spellings have been preserved4 ,typographical and punctuation errors have been silently corrected4 ,,soils ,illustration3 ,the ,,mm ,co ,,their ,,formation1 ,,properties1 ,,composition1 ,,and ,,relations ,,to ,,climate ,,and ,,plant ,,growth ,,in ,,the ,,humid ,,and ,,arid ,,regions ,,by ,e4 ,w4 ,,hilgard1 ,,ph4,d41 ,,ll4,d41 ,,professor ,,of ,,agriculture ,,in ,,the ,,university ,,of ,,california1 ,,and ,,director ,,of ,,the ,,california ,,agricultural ,,experiment ,,station ,new ,york ,,the ,,macmillan ,,company ,,london3 ,,macmillan ,,co41 ,,ltd4 #aiba ,,copyright1 #aijf1 ,,by ,,the ,,macmillan ,,company4 ,set up and electrotyped4 ,published ,july1 #aijf4 ,norwood ,press3 ,berwick ,smith ,co41 ,norwood1 ,mass41 ,u4,s4,a4 ,,summary ,,of ,,chapters4 #a4 ,,origin ,,and ,,formation ,,of ,,soils4 ,introduction4 ,chapter ,i4 ,physical ,processes of ,soil ,formation4 8 ,,ii4 ,chemical ,processes of ,soil ,formation4 8 ,,iii4 ,chief ,soil-forming ,minerals4 8 ,,iv4 ,the ,various ,rocks as ,soil-,formers4 8 ,v4 ,minor ,mineral ,ingredients of ,soils4 ,mineral ,fertilizers4 ,minerals ,injurious to ,agriculture4 #b4 ,,physics ,,of ,,soils4 ,chapter ,,vi4 ,physical ,composition of ,soils4 8 ,,vii4 ,density1 ,pore ,space1 and ,volume-,weight of ,soils4 8 ,,viii4 ,soil and ,subsoil2 ,causes and ,processes of ,differentiation2 ,humus4 8 ,,ix4 ,soil and ,subsoil2 ,organisms ,influencing ,soil-,conditions4 ,bacteria4 8 ,x4 ,soil and ,subsoil in their ,relations to ,vegetation4 8 ,,xi4 ,water of ,soils2 ,hygroscopic and ,capillary ,moisture4 8 ,,xii4 ,water of ,soils2 ,surface1 ,hydrostatic1 and ,ground water2 ,percolation4 8 ,,xiii4 ,water of ,soils2 ,conservation and ,regulation of ,soil ,moisture4 ,irrigation4 8 ,,xiv4 ,absorption by ,soils of ,solids from ,solutions4 ,absorption of ,gases4 ,the ,air of ,soils4 8 ,,xv4 ,colors of ,soils4 8 ,,xvi4 ,climate4 8 ,,xvii4 ,relations of ,soils and ,plant-,growth to ,heat4 #c4 ,,chemistry ,,of ,,soils4 ,chapter ,,xviii4 ,physico-,chemical ,investigation of ,soils in ,relation to ,crop ,production4 8 ,,xix4 ,analysis of ,virgin ,soils by ,extraction with ,strong ,acids1 and its ,interpretation4 8 ,,xx4 ,soils of ,arid and ,humid ,regions4 8 ,,xxi4 ,soils of ,arid and ,humid ,regions continued4 8 ,,xxii4 ,alkali ,soils1 their ,nature and ,composition4 8 ,,xxiii4 ,utilization and ,reclamation of ,alkali ,lands4 #d4 ,,soils ,,and ,,native ,,vegetation4 ,chapter ,,xxiv4 ,recognition of the ,character of ,soils from their ,native ,vegetation4 ,mississippi4 8 ,,xxv4 ,recognition of the ,character of ,soils from their ,native ,vegetation4 ,united ,states at large1 ,europe4 8 ,,xxvi4 ,vegetation of ,saline and ,alkali ,lands4 ,,table ,,of ,,contents4 ,,preface xiii ,,introduction1 xxiii4--,definition of ,soils1 xxiii4--,elements ,constituting the ,earth's ,crust1 xxiii4--,average ,quantitative ,composition of the ,earth's ,crust1 xxiii4--,clarke's ,table1 xxiv4--,oxids ,constitute ,earth's ,crust1 xxiv4--,elements ,important to ,agriculture2 ,table1 xxv4--,the ,volatile ,part of ,plants1 xxvi4 ,,chapter ,i4 ,,agencies ,,of ,,soil ,,formation1 #a4--a4 ,physical ,agencies1 #a4--;,effects of ,heat and ,cold on ,rocks1 #a4--,unequal ,expansion of ,crystals1 #b4--;,cleavage of ,rocks1 #c4--;,effects of ,freezing ,water1 #c4--;,glaciers2 ,figure1 #c4--;,glacier ,flour and ,mud1 #d4--8;,green0 and 8,white0 ,rivers1 #d4--,moraines1 #e4--;,action of ,flowing ,water1 #e4--;,enormous ,result of ,corrasion and ,denudation1 #f4--;,effects of ,winds1 #h4--;,dunes1 #h4--,sand and ,dust ,storms in ,deserts1 ,continental ,plateaus and ,plains1 #h4--,loess of ,china1 #i4--,migration of ,gobi ,lakes1 #i4--;,classification of ,soils1 #aj4--,their ,physical ,constituents1 #aj4--,sedentary or ,residual ,soils1 #aa4--;,colluvial ,soils1 #ab4--;,alluvial ,soils4 ,diagram1 #ab4--;,character of these ,soil ,classes1 #ac4--,richness of ,flood-plain and ,delta ,lands1 #ad4--,lowering of the ,land ,surface by ,soil ,formation1 #ae4 ,,chapter ,,ii4 ,,chemical ,,processes ,,of ,,soil ,,formation1 #af4--b4 ,chemical ,disintegrations or ,decomposition1 #af4--;,ingredients of the ,atmosphere1 #af4--;,effects of ,water2 of ,carbonic ,acid1 #ag4--;,carbonated water a universal solvent1 #ag4--;,ammonic carbonate1 effect on silicates1 #ah4--;,action of oxygen2 on ferrous compounds1 #ah4--;,action of ,plants and their ,remnants1 #ai4--;,a4 ,mechanical2 ,force of ,root ,penetration1 #ai4--;,b4 ,chemical2 ,action of ,root ,secretions1 #ai4--;,bacterial ,action1 #bj4--;,humification1 #bj4--;,causes ,influencing ,chemical ,action and ,decomposition1 #ba4--;,heat and ,moisture1 #ba4--;,influence of ,rainfall on ,soil-,formation1 #bb4--,leaching of the ,land1 #bb4--,residual ,soils1 #bb4--;,drain ,waters2 ,river ,waters4 ,tables of ,solid ,contents1 #bb4--;,amount of ,dissolved ,matters ,carried into the ,sea2 ,amount of ,sediment1 #bd4--,sea ,water1 ,composition of2 ,waters of ,landlocked ,lakes1 #be4--,results of ,insufficient ,rainfall2 ,alkali ,lands1 #bh4 ,,chapter ,,iii4 ,,rock-,,and ,,soil-,,forming ,,minerals1 #bi4--,quartz1 quartzite1 jasper1 hornstone1 flint1 #bi4--,solubility of silica in water2 absorption by plants1 #cj4--,silicate ,minerals1 #ca4--;,feldspars1 their ,kaolinization1 #ca4--;,formation of ,clays1 #cc4--;,hornblende or ,amphibole1 ,pyroxene or ,augite1 #cc4--,their ,weathering and its ,products1 #cc4--,mica1 ,muscovite and ,biotite1 #ce4--;,hydromica1 ,chlorite1 #ce4--,talc and ,serpentine2 8,soapstone01 #cf4 ,the ,zeolites2 ,exchange of ,bases in ,solutions1 #cf4--;,importance in ,soils1 in ,rocks1 #ch4--;,calcite1 ,marble1 ,limestones2 their ,origin1 #ci4--;,impure ,limestones as ,soil-,formers1 #dj4--;,caves1 ,sinkholes1 ,stalactites1 ,tufa1 #da4--;,dolomite2 ,magnesian ,limestones as ,soil-,formers1 #db4--,selenite1 ,gypsum1 ,land ,plaster2 ,agricultural ,uses1 #db4--;,iron ,spar1 ,limonite1 ,hematite1 ,magnetite1 #dd4--,reduction of ,ferric ,hydrate in ,ill-drained ,soils1 #de4 ,,chapter ,,iv4 ,,the ,,various ,,rocks ,,as ,,soil-,,formers1 #dg4--;,general ,classification1 #dg4--,sedimentary1 ,metamorphic1 ,eruptive1 #dg4--,sedimentary ,rocks2 ,limestones1 ,sandstones1 ,clays1 ,claystones1 ,shales1 #dg4--,metamorphic ,rocks3 ,formed from ,sedimentary1 #dh4--;,igneous or ,eruptive ,rocks1 ,basic and ,acidic1 #di4--;,generalities ,regarding ,soils ,derived from ,various ,rocks1 #di4--,variations in ,rocks themselves4 ,accessory ,minerals1 #ej4--;,granites2 not always ,true to ,name2 ,sierra ,granites1 #ea4--;,gneiss4 ,mica-schist1 #ea4--;,diorites1 #ea4--;,diabases1 #ea4--;,eruptive ,rocks2 ,glassy ones ,weather ,slowly2 ,basaltic ,oxidize ,rapidly1 #eb4--,red ,soils of ,hawaii1 ,pacific ,northwest1 #eb4--,trachyte ,soils2 ,light-colored1 rich in ,potash4 ,rhyolites generally make ,poor ,soils1 #ec4--,sedimentary ,rocks1 #ec4--,limestones1 #ec4--8;,a ,limestone ,country is a ,rich ,country10 #ec4--,residual ,limestone ,soils2 from 8,rotten ,limestone0 of ,mississippi2 ,table1 #ed4--,shrinkage of ,surface1 #ee4--,sandstone ,soils1 #ee4--,vary ,according to ,cement1 and ,nature of ,sand1 #ee4--;,calcareous1 ,dolomitic1 ,ferruginous1 ,zeolitic1 #ef4--;,clay-sandstones1 ,claystones1 #eg4--,natural ,clays1 #eg4--;,great ,variety1 ,enumeration and ,definition1 #eh4--;,colors of ,clays1 #eh4--;,colloidal ,clay1 ,nature and ,properties1 #ei4--,plasticity2 ,kaolinite ,non-plastic1 #ei4--;,causes of ,plasticity1 #fj4--,separation of ,colloidal ,clay1 its ,properties1 #fa4--;,effects of ,alkali ,carbonates on ,clay1 #fb4 ,,chapter ,v4 ,,the ,,minor ,,mineral ,,ingredients ,,of ,,soils2 ,,mineral ,,fertilizers1 #fc4--,minerals ,injurious to ,agriculture1 #fc4--,minerals used as ,fertilizers1 #fc4--;,apatite2 ,phosphorites of the ,u4 ,s41 ,antilles1 ,africa1 ,europe1 #fc4--,phosphatic ,iron ,ores1 8,thomas ,slag10 #fd4--;,animal ,bones2 ,composition and ,agricultural ,use1 #fd4--,vivianite1 ,dufrenite1 #fe4--;,chile ,saltpeter1 #ff4 ,occurrence in ,nevada1 ,california1 #ff4--,origin of ,nitrate ,deposits1 #fg4--;,intensity of ,nitrification in ,arid ,climates1 #fh4--,potash ,minerals1 #fh4--;,feldspars not ,available1 #fh4--;,depletion of ,lands by ,manufacture of ,potashes1 #fi4--;,discovery of ,stassfurt ,salts1 #fi4--,origin of these ,deposits1 #gj4--,nature of the ,salts1 #ga4--,kainit1 #ga4--,potash ,salts in ,alkali ,soils1 #gb4--;,farmyard or ,stable ,manure2 ,chemical ,composition1 ,table1 #gb4--;,efficacy largely due to ,physical ,effects in ,soils1 #gc4--;,green-manuring a ,substitute for ,stable ,manure1 #gd4--;,application of ,stable ,manure in ,humid and ,arid ,climates1 #gd4--,minerals ,unessential or ,injurious to ,soils1 #ge4--;,iron ,pyrite1 ,sulphur ,balls1 #ge4--,occurrence and ,recognition4 ,remedies #ge4--;,halite or ,common ,salt1 #gf4--,recognition of ,common ,salt1 #gf4--,mirabilite or ,glauber's ,salt2 in ,alkali ,lands2 not very ,injurious1 #gg4--,trona or ,urao2 ,carbonate of ,soda1 8,black ,alkali10 #gg4--;,injury ,caused in ,soils1 #gh4--;,epsomite or ,epsom ,salt1 #gh4--;,borax1 #gi4--,soluble ,salts in ,irrigation ,waters1 #gi4 ,,chapter ,,vi4 ,,physical ,,composition ,,of ,,soils1 #hc4--;,clay as a ,soil ,ingredient1 #hc4--;,amounts of ,colloidal ,clay in ,soils1 #hd4--;,influence of ,fine ,powders on ,plasticity1 #he4--,rock ,powder2 ,sand1 ,silt and ,dust1 #hf4--,weathering in ,humid and ,arid ,regions1 #hf4--,sands of the ,humid ,regions1 #hf4--,sands of ,arid ,regions not ,sterile1 #hf4--,physical ,analysis of ,soils1 #hh4--,use of ,sieves4 ,limits1 #hh4--,use of ,water for ,separating ,finest ,grain-,sizes1 #hi4--;,elimination of ,clay by ,subsidence and ,centrifugal ,method1 ,hydraulic ,elutriation1 #ij4--,schne's ,instrument1 #ij4--;,churn ,elutriator with ,cylindrical ,tube1 #ia4--;,figures of ,same1 #ia4--,yoder's ,centrifugal ,elutriator1 #ib4--,number of ,grain-sizes ,desirable1 #ic4--,results of such ,analyses1 #ic4--,physical ,composition ,corresponding to ,popular ,designations of ,soil-,quality4 ,table1 #if4--,number of soil-grains per ,gram1 #ii4--,surface ,offered by various ,grain-sizes1 #ii4--;,influence of the several ,grain-sizes on ,soil ,texture1 #ajj4--;,ferric ,hydrate1 its ,effects on ,clay1 #ajj4--,other ,substances1 #aja4--;,aluminic ,hydrate1 #aja4--;,influence of ,granular ,sediments upon the ,tilling ,qualities of ,soils1 #ajb4--8,physical0 ,hardpan1 #ajc4--,putty ,soils1 #ajc4--;,dust ,soils of ,washington2 ,table1 ,physical ,analyses of ,fine ,earth1 #ajd4--,slow ,penetration of ,water1 #aje4--;,effects of ,coarse ,sand1 #aje4 ,,chapter ,,vii4 ,,density1 ,,pore-,,space ,,and ,,volume-,,weight ,,of ,,soils1 #ajg4--;,density of ,soil ,minerals1 #ajg4--,no ,great ,variation1 #ajg4--,volume-weight most ,important1 #ajg4--,weight per ,acre-foot1 #ajg4--;,air-space in ,dry ,natural ,soils4 ,figure1 #ajh4--,may be ,filled with ,water1 #ajh4--;,effects of ,tillage4 ,figures1 #aji4--;,crumb or ,flocculated ,structure2 ,cements1 #aji4--;,how ,nature ,tills1 #aaa4--,soils of the ,arid ,regions2 do not ,crust1 #aab4--;,changes of ,soil-,volume in ,wetting and ,drying1 #aab4--;,extent of ,shrinkage1 #aac4--;,expansion and ,contraction of ,heavy ,clay ,soils4 ,figure1 #aac4--;,contraction of ,alkali ,soils on ,wetting1 #aad4--8;,hog ,wallows10 #aad4--,physical ,analyses of such ,soils4 ,table1 #aae4--;,crumbling of ,calcareous ,clay ,soils on ,drying1 #aaf4--,yazoo ,bottom1 ,port ,hudson ,bluff1 #aaf4--,loamy and ,sandy ,soils1 #aag4--;,formation of ,surface ,crusts1 ,physical ,analyses1 #aag4--;,effects of ,frost on the ,soil2 ,heaving2 ,ice-flowers1 #aah4 ,,chapter ,,viii4 ,,soil ,,and ,,subsoil2 ,,causes ,,and ,,processes ,,of ,,differentiation ,,humus1 #abj4--,soil and ,subsoil ill-defined1 #abj4--,the ,organic and ,organized ,constituents of ,soils1 #abj4--;,humus in the ,surface ,soil1 #abj4--,soil and ,subsoil2 ,causes of their ,differentiation1 #aba4--,ulmin ,substances or ,sour ,humus1 #abb4--,sour ,soils1 #abb4--;,cultivation ,induces ,acidity1 #abc4--;,humin ,substances1 #abc4--,porosity of ,humus1 #abd4--,physical and ,chemical ,nature of the ,humus ,substances4 ,table1 #abd4--;,chemical ,nature1 #abe4--,progressive ,changes and ,effect on ,soils1 #abf4--,the ,phases of ,humification1 ,wood to ,anthracite2 ,table1 #abg4--;,amounts of ,humus and ,coal formed from ,vegetable ,matter1 #abh4--;,figure1 ,from ,port ,hudson ,bluff1 #abh4--;,conditions of ,normal ,humification1 #abi4--;,eremacausis in the ,arid ,regions1 #abi4--;,black ,earth of ,russia2 ,kosticheff's ,table1 #acj4--,losses of ,humus from ,cultivation and ,fallowing1 #aca4--;,estimation of ,humus in ,soils2 ,unreliability of ,combustion ,methods1 #acb4--;,grandeau ,method1 8,matire ,noire10 #acb4--;,amounts of ,humus in ,soils1 #acc4--;,humates and ,ulmates1 #acd4--,mineral ,ingredients in the ,humus1 #acd4--;,functions of the ,unhumified ,organic ,matter1 #ace4--,the ,nitrogen ,content of ,humus1 #ace4--,table for ,arid and ,humid ,soils1 #acf4--;,decrease of ,nitrogen ,content in ,humus with ,depth1 #ach4--,table1 ,russian ,river ,soils1 #aci4--;,influence of the ,original ,material upon the ,composition of ,humus1 #aci4--,table of ,snyder1 #aci4--;,effect of ,humus in rendering ,mineral ,plant ,food ,available1 #adj4 ,,chapter ,,ix4 ,,soil ,,and ,,subsoil 7continued71 #adb4--,,organisms ,,influencing ,,soil-,,conditions4 ,,bacteria1 #adb4--,micro-organisms of the ,soil4 ,bacteria1 ,moulds1 ,ferments1 #adb4--,numbers at ,various ,depths1 given by ,early ,observers1 #adb4--;,investigations of ,hohl2 ,mayo and ,kinsley4 ,tables1 #adc4--,multiplication of the ,bacteria1 #add4--;,aerobic and ,anaerobic ,bacteria1 #add4--;,food ,materials required1 #ade4--;,functions of the ,bacteria1 #ade4--,nitrifying ,bacteria4 ,figures1 #adf4--;,conditions of their ,activity4 ,table1 #adf4--;,effects of ,aeration and ,reduction1 #adg4--,unhumified ,organic ,matter does not ,nitrify1 #adh4--,unhumified ,vegetable ,matter1 ,functions in ,soils1 #adh4--;,denitrifying ,bacteria4 ,figures1 #adh4--;,ammonia-forming ,bacteria4 ,figures1 #adi4--;,alinit1 #adi4--;,effects of ,bacterial ,life on ,physical ,soil ,conditions1 #adi4--,root-bacteria1 or ,rhizobia of ,legumes1 #aej4--;,figures of ,root ,excrescences and ,corresponding ,bacteroids1 #aeb4--,varieties of ,forms1 #aed4--,mode of ,infection1 #aed4--;,cultural ,results1 #aee4--,table ,showing ,increased ,production by ,soil ,inoculation1 #aee4--,other ,nitrogen-absorbing ,bacteria1 #aef4--;,distribution of ,humus in the ,surface ,soil1 #aeg4--;,fungi1 ,moulds and ,algae1 #aeg4--;,animal ,agencies--,earthworms1 ,insects1 ,burrowing ,quadrupeds1 #aeh4 ,,chapter ,x4 ,,soil ,,and ,,subsoil ,,in ,,their ,,relations ,,to ,,vegetation1 #afa4--,physical ,effects of the ,percolation of ,surface ,waters1 #afa4--;,chemical ,effects2 ,calcareous ,subsoils and ,hardpans1 #afa4--8,rawness0 of ,subsoils in ,humid ,climates1 #afb4--,subsoils in the ,arid ,region1 #afc4--;,deep ,plowing and ,subsoiling in the ,arid ,region2 examples of ,plant growth on ,subsoils1 #afd4--,resistance to ,drought1 #afg4--,root ,system in the ,humid ,region1 #afh4--;,figures of the ,root ,system of an ,eastern 7,wisconsin7 ,fruit ,tree1 #afh4--;,comparison of ,root ,development in the ,arid and ,humid ,regions1 #afi4--,prune on ,peach ,root1 #afi4--;,adaptation of ,humid ,species to ,arid ,conditions1 #afi4--;,grapes1 #agj4--,kentucky and ,california ,maize1 #age1 #agf4--;,hops1 #agb4--;,deep-,rooting in the ,arid ,region1 #agd4--;,goose ,foot and ,figwort1 #agd4--;,importance of ,proper ,substrata in the ,arid ,region1 #agc4--;,injury from ,impervious ,substrata4 ,figure1 #agg4--;,faulty ,lands of ,california4 ,figure1 #agh4--,shattering of ,dense ,substrata by ,dynamite1 #aha4--,leachy ,substrata1 #ahb4--8;,going-back0 of ,orchards1 #ahb4--;,hardpan1 ,formation and ,varieties1 #ahc4--,nature of the ,hardpan ,cements1 #ahd4--;,bog ,ore1 ,moorbedpan and ,ortstein2 ,calcareous and ,alkali ,hardpan1 #ahd4--,the ,causes of ,hardpan1 #ahe4--8,plowsole10 #ahf4--,marly ,substrata1 #ahf4 ,,chapter ,,xi4 ,,the ,,water ,,of ,,soils4 ,,hygroscopic ,,and ,,capillary ,,moisture1 #ahh4--;,general ,properties1 #ahh4--,physical ,factors of ,water compared with other ,substances4 ,table1 #ahh4--;,capillarity or ,surface ,tension1 #ahi4--;,heat ,relations1 #aij4--;,density1 #aij4--,specific ,heat and its ,effects1 #aij4 ,ice1 #aia4--,vaporization1 #aia4--,solvent ,power1 #aia4--,water-requirements of ,growing ,plants1 #aib4--;,evaporation from ,plants in ,different ,climates1 #aib4--,relations between ,evaporation and ,plant ,growth4 ,table1 #aic4--;,fortier's ,experiments4 ,figure1 #aid4--;,different ,conditions of ,soil ,water1 #aif4--;,hygroscopic ,water in ,soils2 ,table1 #aif4--;,influence of ,temperature and ,air-,saturation1 #aig4--,utility of ,hygroscopic ,water to ,plant ,growth1 #aii4--,mayer's ,experiments1 #bjj4--,summary1 #bjj4--;,capillary ,water1 #bja4--;,ascent of ,water in ,soil-,columns4 ,table1 #bjb4--;,ascent in ,uniform ,sediments4 ,figure1 #bjd4--,maximum and ,minimum ,water-holding ,power1 #bjg4--;,capillary ,water held at different ,heights in a ,soil ,column4 ,table1 #bjh4--;,capillary ,action in ,moist ,soils1 #baj4--,proportion of ,soil ,moisture ,available to ,plants1 #baa4--,moisture ,requirements of ,crops in the ,arid ,region1 #baa4--,tables of ,observations in ,california1 #bad4 ,,chapter ,,xii4 ,,surface1 ,,hydrostatic ,,and ,,ground ,,water4 ,,percolation1 #bae4--;,amount of ,rainfall1 #bae4--,natural ,disposition of ,rain ,water1 #baf4--,the ,surface ,runoff1 #baf4--,washing-away and ,gullying in the ,cotton ,states1 #bag4--;,injury in the ,arid ,regions1 #bai4--;,deforestation1 #bai4--,prevention of ,injury to ,cultivated ,lands from ,excessive ,runoff1 #bbj4-- ,absorption and ,movements of ,water in ,soils1 #bba4--;,determination of ,rate of ,percolation4 ,diagram1 #bba4--,summary1 #bbd4--;,influence of ,variety of ,grain-sizes1 #bbd4--,table of ,king's ,experiments1 #bbd4--,percolation in ,natural ,soils4 ,figure1 #bbe4--;,ground or ,bottom ,water1 #bbg4--,lysimeters1 ,surface of ,ground ,water2 ,variations1 #bbg4--;,depth of ,ground ,water most ,favorable to ,crops1 #bbh4--,moisture ,supplied by ,tap ,roots1 #bbi4--,reserve of ,capillary ,water1 #bbi4--;,injurious ,rise of ,bottom ,water from ,irrigation1 #bcj4--;,consequences of the ,swamping of ,irrigated ,lands2 ,prevention1 #bca4--,permanent ,injury to certain ,lands1 #bca4--,reduction of ,sulfates1 #bcb4--;,ferruginous or ,red ,lands1 #bcc4 ,,chapter ,,xiii4 ,,water ,,of ,,soils2 ,,the ,,regulation ,,and ,,conservation ,,of ,,soil1 ,,moisture2 ,,irrigation1 #bcd4--,loosening of the ,surface1 #bcd4--;,effects of ,underdrains2 ,rain on ,clay ,soils1 #bce4--,winter ,irrigation1 #bcf4--,methods of ,irrigation1 #bcf4--,surface ,sprinkling1 #bcg4--;,flooding1 #bcg4--;,check ,flooding4 ,furrow ,irrigation1 #bcg1 #bch4--;,figure ,showing ,penetration1 #bci4--;,figure ,showing ,faulty ,irrigation in ,sandy ,lands1 #bci4--;,distance between ,furrows and ,ditches1 #bda4--;,irrigation by ,lateral ,seepage1 #bdb4--;,basin ,irrigation of ,trees and ,vines2 ,advantages and ,objections1 #bdc4--;,irrigation from ,underground ,pipes1 #bde4--,quality of ,irrigation ,waters1 #bdf4--,saline ,waters2 ,figures of ,effects on ,orange ,trees1 #bdf4--,limits of ,salinity1 #bdf4--,mode of ,using ,saline ,irrigation ,waters2 ,apparent ,paradox1 #bdi4--,use of ,drainage ,waters for ,irrigation1 #bej4--8;,black ,alkali0 ,waters1 #bej4--,variations in the ,salinity of ,deep and ,shallow ,wells1 #bej4--,muddy ,waters1 #bea4--,the ,duty of ,irrigation ,waters1 #bea4--;,causes of ,losses1 #beb4--,loss by ,percolation4 ,figure1 #beb4--;,evaporation1 #bec4--,tables ,showing same at ,california ,stations1 #bee4--;,evaporation in ,different ,climates2 ,table1 #bee4--;,evaporation from ,reservoirs and ,ditches1 #beg4--,prevention of ,evaporation2 ,protective ,surface ,layer1 #beg4--;,illustrations of ,effects of ,tillage2 ,table1 #beh4--;,evaporation through ,roots and ,leaves1 #bfb4--,weeds waste ,moisture1 #bfd4--;,distribution of ,moisture in ,soils as ,affected by ,vegetation1 #bfd4--;,forests and ,steppes1 #bfe4--;,eucalyptus for ,drying ,wet ,lands1 #bfe4--,mulching2 ,effects on ,temperature and ,moisture1 #bff4 ,,chapter ,,xiv4 ,,absorption ,,by ,,soils ,,of ,,solids ,,from ,,solutions4 ,,absorption ,,of ,,gases1 ,,air ,,of ,,soils1 #bfg4--;,absorption of ,solids1 #bfg4--;,desalination1 #bfg4--;,decolorization1 #bfg4--;,complexity of ,soil-,action1 ,physical and ,chemical1 #bfh4--8,purifying0 ,action of ,soils on ,gases and ,liquids1 #bfi4--,waste of ,fertilizers1 #bfi4--,variation of ,absorptive ,power1 #bgj4--;,generalities ,regarding ,chemical ,action and ,exchange1 #bgj4--;,drain ,waters1 #bga4--;,distinctions not ,absolute1 #bgb4--;,absorption or ,condensation of ,gases by the ,soil1 #bgb4--,proof of ,presence of ,carbonic and ,ammonia ,gases in ,soils1 #bgc4--;,absorption of ,gases by ,dry ,soils4 ,figure1 #bgd4--;,composition of ,gases ,absorbed by ,various ,bodies from the ,air4 ,table1 #bge4--;,discussion of ,table1 #bgg4--,the ,air of ,soils1 #bgi4--;,empty ,space in ,dry ,soils1 #bgi4--;,functions of ,air in ,soils1 #bgi4--;,insufficient and ,excessive ,aeration1 #bhj4--;,composition of the ,free ,air of ,soils1 #bhj4--;,carbonic ,dioxid vs4 ,oxygen1 #bha4--,relation to ,bacterial and ,fungous ,activity1 #bha4--,putrefactive ,processes1 #bhb4 ,,chapter ,,xv4 ,,colors ,,of ,,soils1 #bhc4--;,black ,soils1 #bhc4--8,red0 ,soils1 #bhd4--,origin of ,red ,tints1 #bhe4--,white ,soils1 #bhe4--;,differences in ,arid and ,humid ,regions1 #bhf4--,white ,alkali ,spots1 #bhf4 ,,chapter ,,xvi4 ,,climate1 #bhg4--;,heat and ,moisture ,control ,climates1 #bhg4--;,climatic ,conditions1 #bhg4--;,ascertainment and ,presentation of ,temperature ,conditions1 #bhh4--;,annual ,mean not a ,good ,criterion1 #bhi4--;,extremes of ,temperature are most ,important1 #bhi4--,seasonal and ,monthly ,means1 #bhi4--;,daily ,variations1 #bij4--,the ,rainfall1 #bij4--;,annual ,rainfall not a ,good ,criterion1 #bij4--;,distribution most ,important1 #bij4--,winds1 #bia4--;,heat the ,cause of ,winds1 #bia4--,trade ,winds1 #bia4--;,cyclones1 #bib4-- ,influence of the ,topography on ,winds2 ,rains to ,windward of ,mountains1 ,arid ,climates to ,leeward1 #bic4--;,general ,distribution of ,rainfall on the ,globe4 ,figure1 #bid4--,ocean ,currents1 #bie4--,the ,gulf ,stream1 #bie4--,the ,japan ,stream1 #bif4--;,contrast of ,climates of ,n4 ,w4 ,america1 #big4--;,continental1 ,coast and ,insular ,climates1 #big4--,subtropic4 ,arid ,belts1 #bih4--,utilization of the ,arid ,belts1 #bii4 ,,chapter ,,xvii4 ,,relations ,,of ,,soils ,,and ,,plant ,,growth ,,to ,,heat1 #cja4--,temperature of ,soils1 #cja4--,water ,exerts ,controlling ,influence1 #cja4--;,cold and ,warm ,rains1 #cjb4--,solar ,radiation1 #cjb4--,penetration of the ,sun's ,heat into the ,soil1 #cjb4--;,change of ,temperature with ,depth1 #cjc4--,surface ,conditions that ,influence ,soil ,temperature1 #cjc4--;,heat of ,high and ,low ,intensity1 #cjd4--,reflection vs4 ,dispersion of ,heat1 #cjd4--;,influence of ,vegetation1 and of ,mulches1 #cje4--;,influence of the ,nature of the ,soil-,material1 #cjf4--;,influence of ,evaporation1 #cjg4--;,formation of ,dew1 #cjg4--;,dew rarely adds ,moisture1 #cjh4--;,dew within the ,soil1 #cjh4--,plant ,development under ,different ,temperature-,conditions1 #cji4--;,germination of ,seeds2 ,optimum ,temperature for each ,kind1 #cji4--;,artificial ,heating of ,soils2 by ,steam ,pipes or ,water1 #caj4 ,,chapter ,,xviii4 ,,physico-,,chemical ,,investigation ,,of ,,soils ,,in ,,relation ,,to ,,crop ,,production1 #cac4--;,historical ,review of ,soil ,investigation1 #cac4--,popular ,forecasts of ,soil ,values1 #cac4--;,cogency of ,conclusions ,based upon ,native ,growth1 #cad4--;,ecological ,studies1 #cae4--;,early ,soil ,surveys of ,kentucky1 ,arkansas and ,mississippi1 #caf4--;,investigation of ,cultivated ,soils1 #caf4--;,change of ,views1 #cag4--;,advantages for ,soil ,study offered by ,virgin ,lands1 #cah4--,practical ,utility of ,soil ,analysis2 ,permanent ,value vs4 ,immediate ,productiveness1 #cai4--,physical and ,chemical ,conditions of ,plant ,growth1 #cai4--;,condition of ,plant-food ,ingredients1 in the ,soil1 #cai4--,water-soluble1 ,reserve1 and ,insoluble ,part1 #cbj4--;,hydrous or 8,zeolitic0 ,silicates1 #cba4--,recognition of the ,prominent ,chemical ,character of ,soils1 #cbb4--;,acidity1 ,neutrality and ,alkalinity1 #cbb4--;,chemical ,analysis1 #cbc4--,water-,soluble and ,acid-,soluble ,portions most ,important1 #cbd4--,we cannot ,imitate ,plant-root ,action1 #cbd ,cultural ,experience the ,final ,test1 #cbd4--;,analysis of ,cultivated ,soils1 #cbe4--,methods of ,analysis1 #cbe4--,the ,solvent ,action of ,water upon ,soils1 #cbg4--;,extraction of ,soils with ,pure ,water1 #cbg4--;,continuous ,solubility of ,soil ,ingredients4 ,tables1 #cbh4--,king's ,results4 ,table1 #cbi4--;,composition and ,analysis of ,janesville ,loam1 #cca4--,solubility of ,soil ,phosphates in ,water1 #ccb4--,practical ,conclusions from ,water ,extraction1 #ccb4--;,ascertainment of the ,immediate ,plant-food ,requirements of ,cultivated ,soils by ,physiological ,tests1 #ccc4--,plot ,tests2 their uncertainties4 ,diagram1 #ccd4--;,crop ,analysis as a ,test of ,soil ,character1 #ccg4--;,chemical ,tests of immediately ,available ,plant ,food2 ,dyer's ,method1 #cch4 ,,chapter ,,xix4 ,,analysis ,,of ,,virgin ,,soils ,,by ,,extraction ,,with ,,strong ,,acids ,,and ,,its ,,interpretation1 #cdj4--,loughridge's ,investigation on ,strength of ,acid and ,time of ,digestion1 #cdj4--,writer's ,method1 #cdb4--,virgin ,soils with ,high ,plant-food ,percentages are always ,productive4 ,table1 #cdc4--;,discussion of ,table1 #cdc4--,low ,plant-food ,percentages not always ,indication of ,sterility1 #cdf4--,what are 8,adequate0 ,percentages of ,potash1 ,lime1 ,phosphoric ,acid and ,nitrogen1 #cdg4--,soil-,dilution ,experiments1 #cdg4--,table of ,compositions1 #cej4--;,figures of ,plants and their ,root-,development1 #cea4--,limitation of ,root ,action1 #cea4--,lowest ,limits of ,plant-food ,percentages and ,productiveness ,found in ,virgin ,soils1 #cec4-- ,limits of ,adequacy of the ,several ,plant-food ,percentages in ,virgin ,soils1 #cec4--,lime a ,dominant ,factor in ,interpretation1 #cec4--,potash1 #ced4--,phosphoric ,acid1 #cee4--;,action of ,lime and ,ferric ,oxid1 #cee4--,table of ,hawaiian ,ferruginous ,soils1 #cef4--,unavailability of ,ferric ,phosphate1 #cef4--,nitrogen1 #ceg4--,nitrification of the ,organic ,matter of the ,soil1 #ceh4--;,analysis of ,soil from the ,ten-,acre ,tract at ,chino1 ,cal41 #ceh4--;,experiments and ,results2 ,matire ,noire the ,only ,guide1 #cfj4--,what are ,adequate ,nitrogen ,percentages in the ,humus8 #cfj4--,table of ,humus and ,nitrogen-,content of ,californian and ,hawaiian ,soils1 #cfa4--;,confirmatory ,experiment4 ,figure1 #cfb4--;,data for ,nitrogen-,adequacy4 ,table1 #cfc4--;,influence of ,lime upon ,soil ,fertility1 #cfe4--8;,a ,lime ,country is a ,rich ,country10 #cfe4--;,effects of ,high ,lime-,content in ,soils1 #cfe4--,table of ,soils showing ,low ,phosphoric ,acid with ,high and ,low ,lime-,content1 #cff4--,what are ,adequate ,lime-percentages8 ,differ for ,light and ,heavy ,soils1 #cfg4--,table ,showing ,need of ,high ,lime ,percentages in ,heavy ,clay ,soils1 #cfh4--;,european ,standards for ,land ,estimates1 #cfi4--,maercker's ,table1 #cfi4 ,,chapter ,,xx4 ,,soils ,,of ,,the ,,arid ,,and ,,humid ,,regions1 #cga4--;,composition of ,good ,medium ,soils2 ,table1 #cga4--;,criteria of ,lands of the ,two ,regions1 #cga4--,tables of ,soil-,composition in ,both ,regions1 #cgb4--,soils of the ,humid ,region governed by ,time1 #cgd4--,soils of the ,arid ,region ,governed by ,moisture1 #cgd4--,lime and ,magnesia ,uniformly ,high in ,arid ,soils1 ,despite ,scarcity of ,limestone ,formations2 ,potash also ,high1 #cgd4--;,general ,comparison of the ,soils of the ,arid and ,temperate ,humid ,regions1 #cge4--;,basis of ,same1 #cgf4--,new ,mexico and ,analysis of ,soil1 #cgf4--;,general ,table1 #cgg4--;,discussion of the ,table1 #cgh4--,lime2 ,summary of ,physical and ,chemical ,effects of ,lime ,carbonate in ,soils1 #cgh4-- ,discussion of ,summary1 #cgi4--,magnesia3 ,its role in ,plant ,nutrition1 #cha4--,manganese3 ,its ,stimulant ,action1 #chc4--,the 8,insoluble ,residue0 or ,silicates1 #chd4--,soluble ,silica and ,alumina1 #chd4--;,analysis of ,clay from ,soil1 #che4--;,difference in ,sand of ,arid and ,humid ,regions4 ,table1 #chf4--,soluble ,silica or ,hydrous ,silicates more ,abundant in ,arid than in ,humid ,soils1 #chh4--;,aluminic ,hydrate4 ,table1 #chi4--,retention of ,soluble ,silica in ,alkali ,soils1 #cia4--;,ferric ,hydrate1 #cib4--,phosphoric ,acid1 #cib4--,sulfuric ,acid1 #cid4--,potash and ,soda1 ,retained more in ,arid ,soils1 #cid4--;,arid ,soils ,rich in ,potash1 #cie4--;,humus1 ,low in ,arid ,soils1 but ,rich in ,nitrogen1 #cif4--,the ,transition ,region1 #cig4 ,,chapter ,,xxi4 ,,soils ,,of ,,arid ,,and ,,humid ,,regions ,,continued1 #cih4--,soils of the ,tropics1 #cih4--;,humus in ,tropical ,soils1 #cii4--;,investigations of ,tropical ,soils1 #dja4--,soils of ,samoa and ,kamerun1 #djb4--,soils of the ,samoan ,islands1 #djc4--,soils of ,kamerun1 #djd4--,soils of ,madagascar1 #dje4--,soils of ,india1 #daj4--,the ,indo-,gangetic ,plain1 #daa4--,the ,brahmaputra ,alluvium in ,assam1 #dac4--;,black ,soils of ,deccan1 #dad4--,red ,soils of the ,madras ,region1 #dae4--,laterite ,soils1 #daf4--;,influence of ,aridity upon ,civilization1 #dag4--,preference of ,ancient ,civilizations for ,arid ,countries1 #dag4--;,irrigation ,necessitates ,co-operation1 #dai4--;,high and ,permanent ,productiveness of ,arid ,soils ,induces ,permanence of ,civil ,organization1 #dai4 ,,chapter ,,xxii4 ,,alkali ,,soils1 ,,their ,,nature ,,and ,,composition1 #dbb4--;,alkali ,lands vs4 ,seashore ,lands1 #dbb4--,origin1 #dbb4--;,deficient ,rainfall1 #dbc4--,predominant ,salts1 #dbc4--;,geographical ,distribution1 #dbd4--,their ,utilization of ,world-wide ,importance1 #dbd4--,repellent ,aspect1 ,plate1 #dbd4--;,effects of ,alkali upon ,culture ,plants4 ,figures of ,apricot ,trees1 #dbf4--,nature of the ,injury1 ,external and ,internal1 #dbf4--;,effects of ,irrigation1 #dbh4--,leaky ,irrigation ,ditches1 #dbi4--,surface and ,substrata of ,alkali ,lands1 #dbi4--,vertical ,distribution of the ,salts in ,alkali ,soils1 #dbi4--;,how ,native ,plants ,live1 #dcj4--;,figures of various ,phases of ,reclamation1 #dca4--,upward ,translocation from ,irrigation1 #dcc4--;,distribution of ,alkali in ,sandy ,lands1 #dcc4--;,in ,heavier ,lands1 #dcf4--,salton ,basin or ,colorado ,delta1 #dcf4--;,diagram of ,alkali ,distribution in ,same1 #dch4--;,horizontal ,distribution of ,alkali ,salts in ,arid ,lands1 #dci4--;,alkali in ,hill ,lands1 #dci4--,usar ,lands of ,india1 #ddj4--8,szek0 ,lands of ,hungary1 #ddj4--;,alkali ,lands of ,turkestan1 #dda4--;,composition and ,quantity of ,salts ,present1 #dda4--,nutritive ,salts1 #dda4--;,black and ,white ,alkali4 ,tables1 #ddb4--;,estimation of ,total ,alkali in ,land1 #ddd4--;,composition of ,alkali ,soils as a whole4 ,tables1 #dde4--,presence of much ,carbonate of ,soda1 #ddh4--;,cross ,section of an ,alkali ,spot4 ,table1 #ddh4--,reactions between the ,carbonates and ,sulfates of ,earths and ,alkalies4 ,figure of ,curve1 #ddi4--;,inverse ,ratios of ,alkali ,sulfates and ,carbonates4 ,diagrams1 #dea4--;,exceptional ,conditions1 #dec4--,summary of ,conclusions1 #dec4 ,,chapter ,,xxiii4 ,,utilization ,,and ,,reclamation ,,of ,,alkali ,,land1 #dee4--;,alkali-resistant ,crops1 #dee4--;,counteracting ,evaporation1 #dee4--,turning-under of ,surface ,alkali1 #def4--,shading1 #deg4--,neutralizing ,black ,alkali1 #deg4--,removing the ,salts from the ,soils1 #deh4--,scraping off1 #deh4--,leaching-,down4 ,figure1 #dei4--,underdrainage1 the ,final and ,universal ,remedy for ,alkali1 #dfj4--,possible ,injury to ,land by ,excessive ,leaching1 #dfb4--;,difficulty in ,draining 8,black0 ,alkali ,land1 #dfb4--,swamping of ,alkali ,land1 #dfc4--,removal of ,alkali ,salts by ,certain ,crops1 #dfc4--,tolerance of ,alkali by ,culture ,plants1 #dfc4--,relative ,injuriousness of the several ,salts4 ,effects on ,sugar ,beets1 #dfd4--,table of ,tolerances2 ,comments on same1 #dfg4--,saltbushes and ,native ,grasses4 ,australian ,saltbushes1 #dfi4--,modiola2 ,native and ,cultivated ,grasses1 #dfi4--,other ,herbaceous ,crops1 #dgb4--,legumes1 #dgb4--,mustard ,family1 #dgc4--,sunflower ,family1 #dgc4--,root ,crops1 #dgd4--,stem ,crops1 #dge4--,textile ,plants1 #dge4--,shrubs and ,trees1 #dge4--,vine1 ,olive1 ,date1 ,citrus ,trees4 ,deciduous ,orchard ,trees4 ,timber and ,shade ,trees1 #dge4--;,inducements toward the ,reclamation of ,alkali ,lands1 #dha4--,wheat on ,reclaimed ,land at ,tulare2 ,figure1 #dhb4--,need of ,constant ,vigilance1 #dhd4 ,,chapter ,,xxiv4 ,,the ,,recognition ,,of ,,soil ,,character ,,from ,,the ,,native ,,vegetation2 ,,mississippi1 #dhg4--;,climatic and ,soil ,conditions1 #dhg4--,natural ,vegetation the ,basis of ,land ,values in the ,united ,states1 #dhh4--;,investigation of ,causes ,governing ,distribution of ,native ,vegetation1 #dhh4--;,investigations in ,mississippi1 #dhi4--,vegetative ,belts in ,northern ,mississippi1 #dij4--,sketch ,map of ,same1 with ,tabulation of ,lime ,content and ,native ,vegetation1 #dij4--,lime ,apparently a ,governing ,factor1 #dib4--,soil ,belts in ,southern ,mississippi1 #dic4--,vegetative and ,soil ,features of ,coast ,belts4 ,diagram1 #die4--,table of ,plant-,food percentages and ,native ,growth1 #dif4--;,definition of ,calcareous ,soils1 #dif4--;,differences in the ,form and ,development of ,trees1 #dih4--;,forms of the ,post ,oak4 ,figures1 #dih4--;,forms of the ,black ,jack ,oak4 ,figures1 #ejj4--;,characteristic ,forms of other ,oaks1 #ejb4--,sturdy ,growth on ,calcareous ,lands1 #ejb4--;,growth of ,cotton1 #ejc4--,lime ,favors ,fruiting1 and compact ,growth1 #ejd4--,physical vs4 ,chemical ,causes of ,vegetative ,features1 #eje4--,lowland ,tree ,growth1 #ejf4--;,contrast between 8,first0 and 8,second0 ,bottoms1 #ejf4--,tree ,growth of the ,first ,bottoms4 ,the ,cypress1 #ejg4--;,figures of ,swamp and ,upland ,cypress1 #ejh4--,other ,lowland ,trees1 #eji4--;,general ,forecasts of ,soil ,quality in ,forest ,lands1 #eji4 ,,chapter ,,xxv4 ,,recognition ,,of ,,the ,,character ,,of ,,soils ,,from ,,their ,,native ,,vegetation4 ,,united ,,states ,,at ,,large1 ,,europe1 #eaa4--;,forest ,growths outside of ,mississippi2 ,alabama1 ,louisiana1 ,western ,tennessee1 and ,western ,kentucky1 #eaa4--,north ,central ,states ,east of the ,mississippi ,river1 #eac4--,upland and ,lowland ,vegetation in the ,arid and ,humid ,region1 #eae4--;,forms of ,deciduous ,trees in the ,arid ,region1 #eaf4--,tall ,growth of ,conifers1 #eag4--;,herbaceous ,plants as ,soil ,indicators1 #eag4--,leguminous ,plants ,usually ,indicate ,rich or ,calcareous ,lands1 #eah4--;,european ,observations and ,views on ,plant ,distribution and its ,controlling ,causes1 #eai4--;,composition of ,pine ,ashes on ,calcareous and ,non-calcareous ,lands4 ,table1 #ebj4--;,calciphile1 ,calcifuge1 and ,indifferent ,plants1 #eba4--,silicophile vs4 ,calciphile ,flora1 #ebc4--,what is a ,calcareous ,soil8 #ebd4--,predominance of ,calcareous ,formations in ,europe1 #ebe4 ,,chapter ,,xxvi4 ,,the ,,vegetation ,,of ,,saline ,,and ,,alkali ,,lands1 #ebg4--,marine ,saline ,lands1 #ebg4--;,general ,character of ,saline ,vegetation1 #ebg4--,structural and ,functional ,differences ,caused by ,saline ,solutions1 #ebh4--;,absorption of the ,salts4 ,table1 #ebi4--;,injury from the ,various ,salts1 #eca4--,reclamation of ,marine ,saline ,lands for ,culture1 #ecc4--,the ,vegetation of ,alkali ,lands1 #ecd4--,reclaimable and ,irreclaimable ,alkali ,lands as ,distinguished by their ,natural ,vegetation1 #ecd4--,plants ,indicating ,irreclaimable ,lands1 #ece4--,tussock ,grass2 ,bushy ,samphire2 ,dwarf ,samphire2 ,saltwort2 ,greasewood2 ,alkali ,heath2 ,cressa2 ,salt ,grass1 #ecf4--,relative ,tolerances of the different ,species2 ,table1 #edi4 ,,appendices4 ,a4--,directions for taking ,soil ,samples1 issued by the ,california ,experiment ,station1 #eec4 ,b4--,summary ,directions for ,soil-,examination in the ,field or ,farm1 #eef4 ,c4--,short ,approximate ,methods of ,chemical ,soil-,examination ,used at the ,california ,experiment ,station1 #efj4 ,general ,index1 #efe4 ,index of ,authors referred to1 #eia4 ,,preface4 ,this volume was originally designed to serve as a text and reference book for the students attending the writer's course on soils1 given annually at the ,university of ,california1 who complained of their inability to find in any connected treatise a large portion of the subject matter brought before them4 ,as all these students had preliminary training in physics1 chemistry and botany1 no introductory chapters on these general subjects were necessary or contemplated2 the more so as good elementary treatises embracing the needful preparation are now numerous4 ,as time progressed1 however1 outside demands for a book embodying the writer's soil studies in the humid and arid regions1 especially the latter1 became so numerous and pressing that the scope of the work has gradually been much enlarged to conform to these demands2 and this1 rather than completeness of detail1 when such detail can be found well given elsewhere1 has been the guide in the necessary condensation of the whole4 ,to give the entire subject matter full elucidation1 would require several more volumes4 ,it may not be unnecessary to explain at the outset why and how this treatise deviates in many respects from previous publications on the same general topic4 ,from boyhood up it has fallen to the writer's lot to be almost continuously in more or less direct contact with the conditions and requirements of newly settled regions1 as well as with those hardly yet invaded even by the pioneer farmer2 where the question of cultural adaptation was yet undetermined or wholly in the dark4 ,being during his active life constantly called upon in his official capacity to give information and advice to pioneer farmers or intending settlers in regard to the merits and adaptations of virgin soils1 the writer's attention was naturally and forcibly directed toward soil investigation as a possible means of determining1 beforehand1 the general prospects and special features of agriculture in regions where actual experience was either non-existent or very brief and partial4 ,in the pursuit of these studies he has been favored by exceptional opportunities1 extending over a varied climatic area reaching on the south from the ,gulf of ,mexico to the ,ohio1 across to the ,pacific coast1 and to ,british ,columbia on the north4 ,that a systematic investigation of soils over so large an area1 covering both humid and arid regions1 should lead to some unexpected and novel results1 is but natural2 and it is the discussion of these results in connection with those obtained elsewhere1 and with some of the prevailing views based thereon1 that must serve as the justification for the present addition to an already well-stocked branch of literature4 ,from the very beginning of the scientific study of agriculture1 the investigation of soils with a view to the priori determination of their adaptation1 permanent value1 and best means of cultural improvement1 has formed the subject of continuous effort4 ,it is not easy to imagine a subject of higher direct importance to the physical welfare of mankind1 whose very existence depends on the yearly returns drawn by cultural labor from the soil4 ,it is certainly remarkable that after all this long-continued effort1 even the fundamental principles1 and still more the methods by which the object in view is to be attained1 are still so far in dispute that a unification of opinion in this respect is not yet in view2 and a return to pure empiricism is from time to time brought forward to cut the ,gordian knot4 ,while this state of things is primarily due to the intrinsic complexity and difficulty of the subject itself1 it has unquestionably been materially aggravated by accidental1 partly historic conditions4 ,foremost among these is the fact that until within recent times1 soil studies have borne almost entirely on lands long cultivated and in most cases fertilized3 thus changing them from their natural condition to a more or less artificial one1 which obscures the natural relations of each soil to vegetation4 ,the importance of these relations is obvious1 both from the theoretical and from the practical standpoint4 ,from the former1 it is clear that the native vegetation represents1 within the climatic limits of the regional flora1 the result of a secular process of adaptation of plants to climates and soils1 by natural selection and the survival of the fittest4 ,the natural floras and sylvas are thus the expression of secular1 or rather1 millennial experience1 which if rightly interpreted must convey to the cultivator of the soil the same information that otherwise he must acquire by long and costly personal experience4 ,the general correctness of this axiom is almost self-evident2 it is explicitly recognized in the universal practice of settlers in new regions1 of selecting lands in accordance with the character of the forest growth thereon2 it is even legally recognized by the valuation of lands upon the same basis1 for purposes of assessment1 as is practiced in a number of ,states4 ,the accuracy with which experienced farmers judge of the quality of timbered lands by their forest growth1 has justly excited the wonder and envy of agricultural investigators1 whose researches1 based upon incomplete theoretical assumptions1 failed to convey to them any such practical insight4 ,it was doubtless this state of the case that led a distinguished writer on agriculture to remark1 nearly half a century ago1 that he 8would rather trust an old farmer for his judgment of land than the best chemist alive40#a #a 8,the ,soil ,analyses of the ,geological ,surveys of ,kentucky and ,arkansas40 ,s4 ,w4 ,johnson in ,am4 ,jour4 ,sci41 ,sept4 #ahfa4 ,it is certainly true that mere physico-chemical analyses1 unassisted by other data1 will frequently lead to a wholly erroneous estimate of a soil's agricultural value1 when applied to cultivated lands4 ,but the matter assumes a very different aspect when1 with the natural vegetation and the corresponding cultural experience as guides1 we seek for the factors upon which the observed natural selection of plants depends1 by the physical and chemical examination of the respective soils4 ,it is further obvious that1 these factors being once known1 we shall be justified in applying them to those cases in which the guiding mark of native vegetation is absent1 as the result of causes that have not materially altered the natural condition of the soil4 ,it is probable that1 had agricultural science been first developed in regions where the external conditions permitted the carrying-out of such a course of investigation1 instead of in the abnormally temperate1 even and humid climate of middle ,europe1 with its long-cropped1 worn fields1 and very predominantly calcareous soils1 the present condition of this science might differ not immaterially from that actually existing4 ,as a matter of fact1 it has attained its present state under very disadvantageous external conditions1 which frequently necessitated a recourse to highly complex and laborious methods and artificial appliances1 for the establishment and maintenance of the conditions which elsewhere might have been found abundantly realized in nature2 thus permitting1 by the multiplication of observations over extended and widely varied areas1 the elimination and control of accidental errors of experiment and observation4 ,just as in historical geology the subdivisions of formations observed and accepted in ,europe formed for many years a procrustean bed upon which the facts observed elsewhere had to be stretched1 so in the domain of soil physics and chemistry1 and even in vegetable physiology1 the observations made in the really exceptional climates and soils of middle ,western ,europe1 have often erroneously been construed as constituting a general basis for unalterable deductions4 ,the rapid extension of civilization and the carrying of minute scientific research into other regions1 now rendered possible by the improved means of communication1 has shown the one-sidedness of some of the views prevailing heretofore1 inasmuch as they are really applicable only to accidental and rather exceptional conditions4 ,it is therefore one object of this volume to present and discuss summarily the facts of physical and chemical soil constitution and functions with reference to the additional light afforded on the wider basis1 embracing both the humid and the arid regions2 of which the latter has1 as such1 received but scant and desultory attention thus far1 to the detriment of both the work of the agricultural experiment stations and of agricultural practice4 ,the book therefore includes the discussion both of the methods and results of direct physical1 chemical and botanical soil investigation1 as well as the subject matter relating to the origin1 formation1 classification and physical as well as chemical nature of soil1 usually included in works on scientific agriculture4 ,in the presentation of these subjects1 it has been the writer's aim to reach both the students in his own classes and in the agricultural colleges generally1 as well as the fast increasing class of farmers of both regions who are willing and even anxious to avail themselves of the results and principles of scientific investigation1 without 8shying off0 from the new or unfamiliar words necessary to embody new ideas4 ,it would seem to be time that the latter class1 and more especially those constituting farmers' clubs1 should learn to understand and appreciate both the terms and methods of scientific reasoning1 which are likely to form1 increasingly1 the subjects of instruction in the public schools4 ,but in order to segregate to some extent the generally intelligible matter from that which requires more scientific preparation than can now be generally expected1 it has been thought best to use in the text two kinds of type2 the larger one embodying the matter presumed to be interesting and intelligible to the general reader1 while the smaller type carries the illustrative detail and discussion which will be sought chiefly by the student4 ,as regards the chemical nomenclature used in this volume1 the writer has not thought it advisable to follow the example set by some late authors in substituting for the well-known names of the bases and acids1 those of the elements1 and still less1 those of the intangible ions4 ,any one who has taught classes in agricultural chemistry will have experienced the difficulty and loss of time unnecessarily incurred in the incessantly recurring transposition of terms1 and complication of formul1 serving no useful purpose save that of academic consistency4 ,it is of at least doubtful utility to present to the farmer1 e4 g41 the inflammable and dangerous elements phosphorus and potassium as prime factors in the success of his crops1 and of healthy nutrition4 ,inasmuch as all the elements are presented to and contained in the plant in compounds only1 and these compounds are themselves1 in the dilute solutions used by plants1 known to be largely dissociated into their basic and acid groups1 it seems to be most natural to present them under the corresponding1 even if not absolutely theoretically correct names of acids and bases1 to which the farmer and the trade have been accustomed for half a century4 ,upon these considerations the long-used designations of potash1 soda1 lime1 phosphoric1 sulfuric1 nitric and other acids and bases have been retained in this volume1 adding the chemical formula where1 as in analytical statements1 a doubt as to their meaning might arise4 ,assuredly1 the diffusion of scientific knowledge should not be needlessly hindered by the adoption of a pedantic mode of presentation4 ,the great breadth of the subject of this volume has rendered inadvisable any extended bibliography1 such as it has of late become customary to add to works of this kind4 ,references have therefore been restricted to publications specially discussed1 and to such as are not widely known on account of limited circulation4 ,the author's warmest acknowledgments are due to ,professor ,r4 ,h4 ,loughridge1 of the ,university of ,california1 for efficient and sympathetic assistance1 both in the revision of the manuscript1 and active personal help in the preparation of the illustrations4 ,without his coperation the preparation and publication of the volume would have been much longer delayed4 ,acknowledgments are also due for helpful suggestions and criticism to ,professors ,l4 ,h4 ,bailey1 of ,cornell ,university1 ,f4 ,h4 ,king1 of ,wisconsin1 and ,jacques ,loeb of the ,university of ,california4 ,e4 ,w4 ,,hilgard4 ,,berkeley1 ,,california1 ,november #ae1 #aije4 ,,introduction4 ,definition of ,soils4--,in the most general meaning of the term1 a soil is the more or less loose and friable material in which1 by means of their roots1 plants may or do find a foothold and nourishment1 as well as other conditions of growth4 ,soils form the uppermost layer of the earth's crust2 but the term does not indicate any such definite average texture as is sometimes implied by its popular use to designate certain loose1 loamy materials found in older geological formations4 ,we do find in these1 not unfrequently1 layers that in the past have served to support vegetation1 as evidenced by remains of plants found therein4 ,but as a rule1 such ancient soils are much compacted and otherwise changed1 and would not now be capable of performing the office of plant nutrition without previous1 long-continued exposure to the same agencies by which all soils were originally formed from pre-existing rocks4 ,within the latter category must be included1 in scientific parlance1 not only the hard rocks known as such in daily life1 but also such soft materials as clay1 sand1 marls1 etc41 which often compose1 partially or wholly1 the bodies of wide-spread geological formations4 ,elements ,constituting the ,earth's ,crust4--,more than seventy elementary substances have been found within the portion of the earth accessible to man2 most of these are present only in very minute proportions2 of those occurring in relatively considerable quantities1 a list showing their approximate proportions is given below4 ,average quantitative composition of the ,earth's ,crust4--,the total thickness of the outer shell of the earth1 thus far known to us1 does not exceed about #ie1jjj feet1 as observed in the accessible rock deposits4 ,estimates of the proportions in which the more abundant elements contribute to the composition of these constituent rocks1 have repeatedly been made4 ,the latest and most widely accepted of these1 by ,f4 ,w4 ,clarke1 of the ,u4 ,s4 ,geological ,survey1 is given herewith4 ,it includes the constituents of the sea and atmosphere as well2 these two constitute about #g per cent of the whole1 #ic per cent being solid rocks4 ,,relative ,,abundance ,,of ,,the ,,elements ,,to ,a ,,depth ,,of ,,ten ,,kilometers4 ,,solid ,,crust ,,ocean ,,mean1 7#ic ,,per ,,cent74 7#g ,,per ,,cent74 ,,including ,,air4 ,oxygen #dg4bi #he4gi #di4ih ,silicon #bg4ba #be4cj ,aluminum #g4ha #g4bf ,iron #e4df #e4jh ,calcium #c4gg #j4je #c4ea ,magnesium #b4fh #j4ad #b4ej ,sodium #b4cf #a4ad #b4bh ,potassium #b4dj #j4jd #b4bc ,hydrogen #j4ba #aj4fg #j4id ,titanium #j4cc #j4cj ,carbon #j4bb #j4jjb #j4ba ,chlorin #j4ja #b4jg #j4ae ,phosphorus #j4aj #j4ji ,manganese #j4jh #j4jg ,sulphur #j4jc #j4ji #j4jd ,barium #j4jc #j4jc ,nitrogen #j4jb ,fluorin #j4jb #j4jb ,chromium #j4ja #j4ja ,it will be noted that one-half of the total consists of oxygen1 and that nearly #hf 7or #dg4bi of the #di4ih7 of this amount is contained in the solid rocks2 nearly #b4ej of the remainder in sea and other water2 and 4#da in the atmosphere1 in the free condition1 in which it serves for the respiration of animals and plants1 and for the various processes of slow and rapid combustion1 or 8oxidation40 ,this relatively small proportion of the whole1 is1 nevertheless1 the most directly important for the maintenance of organic life4 ,oxids ,constitute ,earth's ,crust4--,the vast predominance of oxygen in the above list suggests at once that most of the other elements must exist in combination with it1 i4 e41 as 8oxids40 ,h4 ,s4 ,washington#b has lately revised the estimates heretofore made1 on the basis of a very large number of analyses made by him and others1 of rocks within the ,united ,states1 and gives the following table2 alongside of which is placed a revised estimate by ,clarke1 which also includes rocks from abroad2 both being given in terms of oxids of the several elements4 #b ,u4 ,s4 ,geol4 ,survey1 ,professional ,paper ,no4 #ad1 p4 #ajh4 ,,washington4 ,,clarke4 ,silica ,si,o #eg4gh #ei4hi ,alumina ,al,o #ae4fg #ae4de ,peroxid of ,iron ,fe,o #c4ca #b4fd ,protoxid of ,iron ,fe,o #c4hd #c4ec ,magnesia ,mg,o #c4ha #d4cg ,lime ,ca,o #e4ah #d4ia ,soda ,na,o #c4hh #c4ef ,potash ,k,o #c4ac #b4ha ,water1 basic ,h,o #a4db #a4eb ,water1 acid ,h,o 4#cf 4#dj ,ferric ,sulphid ,fe,s #a4jc 4#fj ,phosphoric acid ,p,o 4#cg 4#bb ,manganese ,protoxid ,mn,o 4#bb 4#aj ,the salient point which at once attracts attention in these tables is the great predominance of the oxid of silicon--silica1 silicic acid1 quartz1 etc41--over all other substances4 ,while quartz occurs alone in enormous masses1 as will be shown later1 probably the greater proportion is found in combination with other oxids1 notably those of aluminum1 calcium1 iron1 magnesium1 and the alkali metals potassium and sodium4 ,chlorin and fluorin1 however1 do not occur as oxids4#c #c ,a trifling amount of chlorin is found oxidized in the form of sodium perchlorate1 in the nitre deposits of ,chile4 ,the ,chemical ,elements ,important to ,agriculture4--,of the numerous elements known to chemists1 only eighteen require mention in connection with either soil formation or plant growth2 and of these only thirteen or fourteen participate in normal plant growth4 ,they are the following3 ,,metallic ,,elements4 ,,non-,,metallic ,,elements4 ,potassium ,carbon ,sodium ,hydrogen ,calcium ,oxygen ,magnesium ,nitrogen ,iron ,phosphorus ,manganese ,sulphur ,aluminum ,chlorin ,titanium ,fluorin ,iodin ,silicon4 ,of this list1 titanium1 though a very constant ingredient of soils in the form of titanic dioxid1 is not known as performing any important function in soils1 and is not1 so far as known at present1 ever taken up by plants4 ,aluminum1 in the form of its compounds with oxygen and silicon1 is a very prominent and physically very important soil ingredient1 but does not1 apparently1 perform any direct function in plant nutrition1 and is absent from their ash1 except in the case of some of the lower plants 7horsetails and ferns74 ,iodin appears to be normally present in all seaweeds1 and occurs in traces in some land plants4 ,fluorin is a normal ingredient of animal bones1 and its presence in plant ashes is often easily shown4 ,the remaining fourteen1 however1 are always present in plants2 carbon1 hydrogen1 oxygen and nitrogen forming the volatile or combustible part1 while the rest occur in the ashes4 ,it is true that other elements1 or rather their compounds1 are sometimes found in plants1 being taken up by them from solutions existing in the soil4 ,thus the alkalies caesium and rubidium1 also barium1 strontium1 zinc1 copper1 boron and some others1 may be absorbed when present in soluble form4 ,but they are neither necessary nor beneficial to plant economy1 and when in considerable amounts are harmful4 ,thus fifteen elements1 ommiting iodin and titanium1 alone require discussion4 ,the ,volatile ,part of ,plants1 as already stated1 consists of carbon1 hydrogen1 oxygen and nitrogen4 ,of these1 carbon is obtained by the plant exclusively from the carbonic 7dioxid7 gas of the air2 hydrogen and oxygen1 from the soil in the form of water2 nitrogen1 directly from the soil but indirectly also from the air1 through the agency of certain bacteria4 ,the ash ingredients of course are all derived from the soil through the roots1 and must all be present in the latter in an available form1 to a sufficient extent to supply the demands of vegetation4 ,the ,agencies of ,soil ,formation4--,with respect to their mode of formation1 soils may be defined as the residual product of the physical disintegration and chemical decomposition of rocks2 with1 ordinarily1 a small proportion of the remnants of organic life4 ,the agencies producing these changes are those classed under the general term 8atmospheric0 or 8meteorological20 they include therefore the action of temperature--heat and cold--that of water1 and that of air and its ingredients4 ,in popular parlance1 it includes the processes of weathering2 nearly the same processes are involved in the 8fallowing0 of soils4 ,,part ,i4 ,,the ,,origin ,,and ,,formation ,,of ,,soils4 ,,chapter ,i4 ,,the ,,physical ,,processes ,,of ,,soil ,,formation4 ,since the physical and mechanical effects of the agencies mentioned above usually precede1 in time1 the chemical changes1 which are materially facilitated by the previous pulverization of the rocks1 the former should be first considered4 ,effects of heat and cold on rocks4--,most rocks are aggregates of several simple minerals2 a few only 7limestone1 quartzite and a few others7 expand or contract alike in all their parts4 ,of the minerals composing the compound rocks1 scarcely any expand to exactly the same extent under the influence of the sun's heat1 especially when their colors differ2 nor1 in the great majority of cases1 does one and the same mineral expand alike in all three directions4 ,it follows that at each change of temperature there is a tendency to the formation of minute fissures between adjacent crystals or masses of different simple minerals2 and especially in the case of large crystals of certain kinds1 this action alone will gradually result in the disruption of the rock surface1 so that individual crystals may be detached with little difficulty4 ,in any case1 the cracks so formed are gradually widened by a frequent repetition of the changes of temperature1 coupled with access of air1 water1 dust1 and the rootlets of plants2 all of which brings about a gradually increasing rate of surface crumbling4 ,this is especially conspicuous at the higher elevations of mountains1 where the temperature changes are very great and abrupt2 and also in the clear atmosphere of deserts1 where owing to the extent and suddenness of temperature-changes between day and night1 caused by the free radiation of heat into the clear sky1 even homogeneous pebbles are known to be almost explosively disrupted in the mornings and evenings of clear days4 ,such effects may often be strikingly observed on small surfaces of compound crystalline rocks1 such as granite1 exposed on glaciers1 where the daily changes of temperature are often extreme1 viz41 from below the freezing point to as much as #acj degrees ,fahr4 7#ed4d degrees ,c74 ,in such cases one may sometimes scoop off the disintegrated rock by the handful1 while yet the mineral surfaces are almost perfectly fresh4 ,on a larger scale1 the disruption and scaling off of huge slabs of granite1 and rocks of similar structure1 may be observed in southern ,california on the southwestern side of rock exposures1 where slabs from a few inches to ten and more feet in length and eight or ten inches thick1 have slid off1 perhaps still leaning against the parent rock1 which has been rounded off by a succession of such events into the domelike form so characteristic of granite mountains4 ,merrill#d reports similar exfoliations to occur especially on the peninsula of ,california1 on ,stone ,mountain in ,georgia1 and elsewhere4 #d ,see ,rocks1 ,rock-weathering1 and ,soils1 page #bdf2 also paper on ,domes and ,dome ,structure1 by ,g4 ,k4 ,gilbert1 in ,bulletins of the ,geol4 ,society ,am41 ,vol4 #ae1 pp4 #bi-cf4 ,a striking exemplification of the effects of frequent and rapid changes of temperature on rocks1 and of humid and dry climates as well1 is seen in the case of the great monoliths of ,egypt1 one of which now stands in the ,central ,park1 ,new ,york4 ,in the quarries of ,syene in ,upper ,egypt1 where most of these monoliths were obtained1 the rough blocks that were in progress of quarrying when the work was abandoned1 quite two thousand years ago1 still show an almost perfectly fresh surface2 and the same is true of the finished obelisks in ,lower ,egypt1 where both the changes of temperature and the rainfall are somewhat greater4 ,it is a matter of public note that one of 8,cleopatra's ,needles0 which was set up in ,central ,park nearly thirty years ago1 but originally erected at ,heliopolis on the ,nile1 is in great danger of destruction from the influence of a totally different climate1 in which both the temperature changes and the rainfall are much more frequent and severe than in ,egypt4 ,the large crystals of feldspar and quartz which compose the 7syenite7 rock material have had fine fissures formed between them by often-repeated expansion and contraction2 which when filled with water and subsequently changed to ice1 the latter's expansion in freezing 7see below7 has still farther enlarged them and caused a scaling-off1 which threatens to obliterate the hieroglyphic inscriptions4 ,thus temperature-changes and a rain followed by freezing may in a few days produce a greater effect than a thousand years of ,egyptian climate4 ,cleavage of rocks4--,many kinds of rocks have definite directions of ready cleavage4 ,the most common and obvious cases of this kind are schists1 slates and shales1 cleaving readily into plates or irregular flat or lens-shaped fragments4 ,such structure greatly favors disintegration1 especially when the layers are on edge at steep angles4 ,but there are other apparently structureless1 massive rocks1 particularly basalts and other eruptive rocks related to them1 as well as many sandstones and claystones1 that have a strong tendency to cleave into more or less definite forms when struck2 such as columns or prisms1 square1 six-sided or diamond-shaped blocks1 etc4 ,similar forms are naturally produced in them under the influence of changes of temperature2 by the formation of minute cracks at first1 then enlargement of these by the several agencies already mentioned4 ,effects of freezing water4--,the irresistible force exerted by the expansion of water in freezing1 amounting to about #i per cent of its bulk1 is a powerful factor in widening and deepening fissures and cracks of rocks2 not uncommonly1 whole masses of rock are rent into fragments by this agency1 which is one of the most common causes of 8rock falls0 on the brink of precipices4 ,by the freezing process cracks and crevices are enlarged1 and the surfaces exposed to weathering are still farther increased2 and the rock fragments or soil particles are loosened and rendered more liable to be removed from the original site1 whether by gravity1 wind or water4 ,glaciers4--,ice in the form of the glaciers that descend from mountain chains 7see figure #a71 and of the moving ice sheets that have covered large portions of ,north ,america and ,europe in past ages and now cover ,greenland and the ,south ,polar continent1 exerts a most potent action in abrading and grinding even the hardest rocks2 not so much by the direct friction of the moving ice itself1 as by the cutting1 scoring1 grinding and crushing action which the stones imbedded in the ice1 or carried and shoved by it1 exert upon the rocky channels in which the ice stream moves1 as well as upon each other4 ,the product of this grinding process is largely very fine 7hence 8glacier flour071 so that it remains suspended in the water of the glacier-streams until their velocity is permanently checked when reaching a plain or lake4 ,this suspended stone-flour imparts to the glacier streams their distinctive character of 8white rivers10 as contradistinguished from the clear1 dark 8green rivers0 that have their origin outside of glaciated areas4 ,this difference can be readily observed in traveling along any of the glacier-bearing mountain chains of the world1 and is frequently expressed in the names of the streams4 ,illustration3 ,,fig4 #a4--,zermatt ,glacier 7,agassiz74 ,the physical analysis of mud from the foot of ,muir glacier1#e ,alaska1 at its sea front1 made by ,professor ,loughridge1 shows the prevalent fineness of the materials brought down by the glacier waters4 #e ,collected by ,dr4 ,w4 ,e4 ,ritter of the ,university of ,california4 ,,physical ,,composition ,,of ,,glacier ,,mud4 ,,material4 ,,diameter4 ,,per ,,cent4 ---------------------------------------- ------- ,clay 8 #af4eg #gj4ca ,fine silt 4#jjbc -- 4#jaf mm4 #ec4gd ,fine silt 4#jaf to 4#jbe mm4 #d4ch ,medium silt 4#jbe to 4#jcf mm4 #g4jf ,coarse silt 4#jcf to 4#jdg mm4 #e4ia ,coarse silt 4#jdg to 4#jgb mm4 #c4gf ,fine sand 4#jgb to 4#ab mm4 #a4ad ,medium sand 4#ab to 4#af mm4 #a4ef ----- ,total #id4ab ---------------------------------------- ------- ,it will be noted that over #gj per cent of this mud consists of extremely fine1 wholly impalpable materials2 but little of which is true clay4 ,the fineness of the glacier flour renders it peculiarly suitable for the rapid conversion into soil1 and such soils are usually excellent and remarkably durable4 ,the great and lasting fertility of the soils of southern ,sweden is traced directly to this mode of origin1 and doubtless the great ,american ice sheet of glacier times is similarly concerned in the high quality of the soil of our 8north central0 states1 from the ,ohio to the ,great ,lakes and the ,missouri4 ,the accumulations of rocks and debris of all sizes in the 8moraines0 or detrital deposits of glaciers and ice-sheets form another class of glacier-made lands which cover extensive and important agricultural areas 7drift areas71 both in the old and new worlds4 ,such lands are undulating or slightly hilly1 and the soil usually contains imbedded in it stones of a great variety of kinds and sizes1 partly angular1 partly rounded and polished by friction4 ,of course the frequent and violent changes of temperature occurring on the surface of a glacier1 aid materially in reducing the rocks carried by it to the condition in which we find the material of the moraines2 which commonly form lateral or cross ridges in valleys formerly occupied by glaciers4 ,action of flowing water4--,the action of flowing water is doubtless at this time the most potent mechanical agency of soil formation4 ,from the sculpturing of the original simple forms in which geological agencies left the earth's surface into the complex ones of modern mountain chains1 to the formation of valleys1 plains1 and basins out of the materials so carried away1 its effects are prodigious4 ,the torrents and streams in carrying silt1 sand1 gravel and bowlders1 according to velocity and volume1 do not merely displace these materials2 the rock fragments of all sizes not only score and abrade the bed of the rill or stream1 but by their mutual attrition produce more or less of fine powder similar to that formed by glacier action2 usually more mixed in its ingredients than the former1 because derived from a wider range of drainage surface4 ,in the glacier stream itself1 it is easy to trace the gradual transition from the sharp stone fragments lying in the water as it issues from the terminal ice cave at the lower end of the glacier1 to the rounded shingle found a few miles below4 ,illustration3 ,,fig4 #b4--;,erosion of ,hawaiian ,hills1 near ,honolulu4 7,phot4 by ,h4 ,c4 ,myers47 ,on slopes where water flows only during rain or the melting of snow1 the same erosive effects may be seen as between the heads of ravines and their outlets4 7,see figure #b17 ,it is there too that the surprisingly rapid cutting-out of channels by the aid of water charged with rock fragments or gravel1 can readily be observed1 and the enormous power of water erosion convincingly shown4 ,in the ,united ,states the stupendous gorges of the ,columbia and ,colorado rivers1 the former cut to a depth of over #bjjj feet into hard basalt rock1 the latter to over #e1jjj feet1 partly into softer materials1 partly into granite1 are perhaps the most striking examples of this power2 the manifestations of which can1 however1 be as convincingly seen in thousands of minor rivers and streams4 ,all the materials so carried off from the higher slopes are finally deposited on a lower level2 whether only a short distance away on a lower slope 7colluvial soils71 or farther away in the flood plain of streams1 rivers1 or lakes 7alluvial soils74 ,other things being equal1 the finest materials are of course1 carried farthest1 and often into the sea2 in which1 however1 they cannot long remain suspended1 but are quickly thrown down1 forming river bars1 flood plains1 and deltas4 ,the fineness of the material of delta soils1 like that of those made from glacier flour1 insures them the same advantage1 viz4 great fertility and durability4 ,it is calculated that the ,mississippi ,river carries into the ,gulf of ,mexico annually some #gdfi millions of cubic feet of earthy deposits1 which would fill one square mile of surface to the height of #bfh feet1 or would cover that number of square miles to the depth of one foot4 ,illustration3 ,,fig4 #c4--;,cliffs and caves on sea-beach at ,la ,jolla1 ,calif4 showing effects of ,wave action4 ,wave-,action4--,the powerful effects of the beating of waves upon abrupt shores of seas or lakes are in evidence all over the world1 and these effects are so characteristic that they can be recognized even where no sea or lake exists at present4 ,gravel and sand are carried in the surf and serve as grinding materials1 wearing even the hardest rocks into grooves1 rills1 channels and caves1 defining sharply the varying degrees of hardness or tough resistance in different parts of rocky cliffs2 frequently undermining them and causing extensive rock falls4 ,the latter then serve for a time to break the violence of the waves' onset1 and may even cause permanent shore deposits to be formed under their lee4 ,such deposits are very generally formed on gently sloping beaches1 and as the water gradually recedes1 sometimes by elevation of the ground1 beach lines or beach-terraces are left1 which indicate the successive levels of the lake or sea4 ,such old beach lines or terraces and level-surfaced 8buttes0 in the ,great ,basin country1 and 8bench lands0 elsewhere1 show in their structure the characteristic lines of wave-deposition4 ,effects of ,winds4--,the action of winds in transporting soil particles 7dust and sand7 is familiar2 and the accumulations that may be formed under the influence of regular1 continuous winds are sufficiently obvious on lee shores having sandy beaches1 inland of which the formation of sand dunes at times assumes a threatening magnitude4 ,where winds are irregular1 frequently reversing their direction1 of course the local effects will be less obvious1 and the transportation of material actually occurring will often not be noticed4 ,yet there can be no doubt of the importance of wind action in soil formation1 and there are cases in which no other agency can explain the facts observed over widely extended areas4 ,this is especially true with regard to the soil masses of the high plains or plateaus of the dry continental interiors1 where not only the regularity of the prevailing winds1 but also the structure 7or absence of structure7 and pulverulent character of the soil itself1 renders this the only rational mode of accounting for its presence where we find it4 ,the effects that may be exerted by regular winds are well illustrated in the plains and deserts of ,africa as well as those of central ,asia4 ,here we find a distinct subdivision of the desert 7rainless7 areas into the stony1 from which the wind has swept all but the bedrock and gravel and where scarcely any natural growth1 and certainly no cultivation is possible in the almost total absence of soil4 ,the next subdivision is the sandy desert1 to leeward of the stony area1 where the winds are less violent and regular1 and where1 therefore1 the sand has been dropped and is waited back and forth by 8sand storms10 the surface being covered with moving sand dunes4 ,still farther to leeward we find the region in which the finer portions of the desert surface has been deposited2 here we have 8dust storms0 so long as the land is not irrigated3 but the application of water renders the soil abundantly fruitful4 ,such is the case of the ,oases and fertile border-lands of the ,sahara and ,libyan deserts4 ,in the cultivated portions of the ,mojave and ,colorado deserts in ,california1 plowing of the land during a dry time is not uncommonly followed by a bodily removal of the loosened soil to neighboring fields1 sometimes leaving a gravel surface behind4 ,such 8blown-out lands0 exist naturally at numerous points in the ,colorado desert4 ,sven ,hedin 7,central ,asia and ,tibet1 ,vol4 ,,ii47 shows that from the effects of the violent storms that prevail in the ,gobi or ,takla ,makan desert1 ,lop-nor lake1 the sink of the ,tarim river1 has in the course of time shifted its bed as much as fifty miles in consequence of the excavation of the southern part of the desert by the wind2 while the sand so blown out1 together with the deposits from the rivers1 now tends to fill up the present 7southern7 lake1 which is gradually returning northward toward its original site1 now a desert1 but around which formerly a dense population existed4 ,the great plains of ,north ,america1 the pampas of ,south ,america1 the plateaus of ,mongolia and especially the fertile loess region of northwestern ,china1 are also cases in point4 ,the dense dust storms of these regions are familiar and unpleasant phenomena1 which are often observed even by vessels at sea off the east coast of ,south ,america1 where the dust-laden 8pamperos0 at times compel them to proceed with the same precautions as in a fog2 and the same is true of the northeast winds blowing off the ,sahara desert on the west coast of ,africa4 ,the effects of windstorms carrying sand in the erosion of rocks are very obvious and striking in many parts of the world2 nowhere probably as much so as on the great plains of western ,north ,america1 where the geological composition of the 8bad lands0 is frequently impressed upon the rock surfaces very prominently4 ,the strikingly grotesque forms are frequently brought out in this way1 especially in the case of 8mushroom0 rocks1 where a hard stratum has remained as a covering while softer layers underneath have been worn away4 ,the illustration annexed shows such a case on the plains of ,wyoming as figured in the ,report of the ,u4 ,s4 ,geological ,survey1 on the ,central ,great ,plains1 by ,n4 ,h4 ,darton4 ,striking examples of the same effects are seen on the shores of ,lake ,michigan in the ,grand ,traverse region1 where the rocky cliffs are visibly worn away and carved under the influence of the regular 8sand-blasts0 of northwest winds4 ,on a smaller scale the effects of these sand-blasts may be noted in the cobble-deserts1 where we frequently find the cobbles worn away on the windward side in a very characteristic manner2 the lee side remaining rounded and smooth1 while the structure of the rock is strongly outlined on the windward side4 ,illustration3 ,,fig4 #d4--8,mushroom rocks10 produced by ,wind action1 ,wyoming4 7,darton47 ,,classification ,,of ,,soils4 ,the physical ,constituents of soils are thus1 in the most general terms1 first1 rock powder 78sand07 more or less changed by weathering2 second1 clay1 as one of the chief results of the weathering process of silicate minerals2 and thirdly1 humus1 the dark-colored remnant of vegetable decay4 ,according to the obvious predominance of one or the other of these primary ingredients1 soils are popularly1 in the most general sense1 classed as 8heavy0 and 8light02 the former term corresponding as a rule to those in which clay forms a prominent ingredient1 while sandy and humous or 8mold0 soils usually fall under the latter designation1 because of their easy tillage4 ,for practical purposes these subdivisions are both convenient and important1 and they form the ordinary basis of land classification4 ,beyond these1 the degree of fineness of the rock debris1 and their physical and chemical constitution1 determine distinctions such as gravelly1 sandy1 silty1 loamy1 calcareous1 siliceous1 magnesian1 ferruginous1 and others of less general application1 though locally often of considerable importance4 ,for the purposes of discussion and definition1 however1 another basis of classification is needed1 which essentially concerns both the origin and the adaptations of lands4 ,illustration3 ,,fig4 #e4--;,diagram illustrating the genetic relation of different soil classes to each other4 #a4 ,sedentary ,soils4--,when soils have been formed without removal from the site of the original rock1 by simple weathering1 they are designated as sedentary1 or residual soils1 or 8soils in place40 ,in the case of these1 the original rock underlies the soil or subsoil at a greater or less depth1 according to the intensity and duration of the weathering process1 and is usually more or less softened and decomposed at the surface where it meets the soil layer4 ,the latter of course bears some of the distinctive characters of the parent rock1 and its composition and adaptations may1 in a measure1 be directly inferred from that origin4 ,such soils usually contain1 especially in their lower portions1 some angular fragments of the parent rock4 ,in some cases sedentary soils may have been partially derived from rocks that have been removed from above the present country rock by erosion1 and in that case fragments of such vanished rock may also be present4 ,sedentary soils are most commonly found on rock plateaus and on slopes or plains underlaid by rock strata of but slight inclination1 where the velocity of the 8runoff0 rainfall is not sufficient to dislodge the rock debris4 ,extended areas of such soils exist in the granitic areas of the southern ,alleghenies1 in the 8black prairies0 of the ,cotton ,states1 and on the 8basaltic0 plateaus of the ,pacific ,northwest4 #b4 ,colluvial ,soils4--,when the soil mass formed by weathering has been removed from the original site to such a degree as to cause it to intermingle with the materials of other rocks or layers1 as is usually the case on hillsides1 and in undulating uplands generally1 as the result of rolling or sliding down1 washing of rains1 sweeping of wind1 etc41 the mixed soil1 which will usually be found to contain angular fragments of various rocks1 and is destitute of any definite structure1 is designated as a colluvial#f one4 ,colluvial soil masses are frequently subject to disturbance from landslides1 which are usually the result of water penetrating underneath1 between the soil mass and the underlying rock1 or sometimes simply of complete saturation of the former with water4 ,aside from such catastrophic action1 they commonly have a slow downward movement in mass 7creep71 which ordinarily becomes perceptible only in the course of years2 most quickly where there are heavy frosts in winter1 which act both by direct expansion1 and by the state of extreme looseness in which the soil mass is left on thawing4 ,colluvial soils form a large portion of rolling and hilly uplands1 and are of very varying degrees of productiveness4 #f ,the term 8overplaced10 used for such soils in late memoirs of the ,u4 ,s4 ,geological ,survey1 is at least superfluous1 in view of the perfectly understood term already in general use1 and does not seem to commend itself for adoption by any special or superior fitness2 nor does the suggestion of ,shaler 7,the ,origin and ,nature of ,soils1 #abth ,rep4 ,u4 ,s4 ,geol4 ,survey7 to include the colluvial soils within the alluvial class1 commend itself either from a theoretical or practical point of view1 since but few useful generalizations can apply to both classes4 #c4 ,alluvial ,soils4--,when soils are the result of deposition by streams1 the material having been gathered along the course of the stream from various sources and carried to a distance before being deposited1 the soil is designated as alluvial4 ,these are the soils of the valleys1 flood-plains1 and sea- and lake-borders1 past and present4 ,being of mixed origin1 their general character may vary from one extreme to the other1 both as regards physical and chemical composition4 ,since1 moreover1 they represent the finer portions of the soils of the regions drained by the water-courses1 alluvial soils are as a rule of a fine texture2 and as representing the most advanced decomposition products of the parent rocks1 they are usually preminently fertile4 ,this is proverbially true of the flood-plains of rivers1 and still more of their deltas--the bodies of lands formed near their outlets into seas or lakes4 ,character of these soil-classes4--,sedentary soils are as a matter of course1 other things being equal1 dependent entirely on the parent rock for their specific character2 and taking into consideration the various rocks 7usually one or few7 from which they may have been derived1 nearly the same is true of colluvial soils1 except that a portion of the clay and finest pulverulent matters may in their case be carried down on the lower slopes and into the valleys and streams1 by the hillside rills4 ,according to the calculation of ,merrill 7,rocks1 ,rock-weathering1 and ,soils1 p4 #ahh7 granite when transformed into soil without loss would increase in weight by #hh2 more than doubling its bulk4 ,more usually1 the leaching process diminishes their volume as compared with the parent rock4 ,alluvial soils are also of course to a certain extent dependent upon the character of the rocks and surface deposits occurring within the drainage area of the depositing stream4 ,as a rule their composition is much more generalized2 but their character as to the relative proportions of sand and clay is essentially dependent upon the velocity of the water current4 ,thus in the upper portions of valleys1 where the slope is relatively steep and the velocity therefore high1 a large proportion of cobbles and gravel is often present in the deposits1 sometimes to the extent of rendering cultivation impracticable1 or at least unprofitable4 ,as the slope and velocity decrease1 first coarse and then fine sand will be the prominent component of the deposited soil2 while still lower down1 in the region of slack water1 the finest sand or silt1 together with clay1 will predominate4 ,according to ,hopkins1#g flowing water will1 at a velocity of three inches per second1 carry in suspension only fine clay 7and silt72 at eight inches it will carry sand as large as linseed4 ,at one and one-third inches1 it will move pebbles one inch in diameter2 and at a velocity of two inches per second1 pebbles of egg size are moved along the stream bed4 ,since the velocity of streams subject to freshets will vary greatly from time to time1 deposits of very different grain will in such cases be found alternating with one another in the soil stratum of the flood plain4 ,in fact1 this alternation and the more or less stratified structure resulting therefrom1 is the distinguishing mark of alluvial soils as such4 ,it is true that this peculiarity is also sometimes found in the case of lands now lying far above the flood-plains of present rivers2 but this is due to the elevation of the land or the depression of the river channels at a former period1 prior to which such lands 7commonly known as river terraces1 benches or second bottoms7 were formed4 ,the same is true of lake terraces 78mesas071 which cover enormous areas in some parts of the world1 more particularly in western ,north ,america4 ,it must nevertheless be remembered that such alluvial terrace or bench soils differ in some respects from the modern alluvials1 on account of their long exposure to atmospheric action alone2 one result of which is that they are usually much poorer in humus1 and therefore of lighter tints1 than the more modern soils of alluvial origin4 ,other differences will be adverted to hereafter4 #g ,geikie1 8,text-book of ,geology10 #c;d ed4 ,as a matter of course the above distinctions1 especially between colluvial and alluvial soils1 cannot be rigorously maintained in all cases4 ,there are transitions from one class to the other1 so that it is sometimes optional with the observer to which of the two classes a particular soil may be considered as belonging4 ,on the lower slopes of the hills bordering alluvial valleys the colluvial slope-soil may often be found alternating with the alluvial deposits1 or bodily washed away to be redeposited as alluvium at a greater or less distance4 ,one characteristic of the flood-plain lands of all the larger rivers1 and more or less of all streams subject to periodic overflows1 is that the land immediately adjoining the banks is both higher and more sandy than are the lands farther back from the stream4 ,the cause of this phenomenon is that as lateral overflow diminishes the velocity of that flow1 its coarser portions are deposited near the river banks1 while the finer particles are carried farther away1 until finally only the finest--clay-substance--reach the lagoons or lakes filled with the overflow or backwater1 and are there in the course of time deposited as heavy clay 8swamp0 soils4 ,the same occurs where rivers empty into lakes or the sea2 and these slack-water or delta lands are1 as a rule1 the most productive on the river's course4 ,the continued productiveness of alluvial soils is moreover in many cases assured by the deposition1 during overflows1 of fresh soil-material brought down from the head waters of the streams4 ,the ,nile1 and the ,colorado river of the ,west1 illustrate this point4 ,lowering of the land-surface by soil formation4--,it is evident that the soil-forming agencies must in the course of time materially affect both the surface conformation and the absolute level of the land4 ,the sharp pinnacles and crests of rock are abraded into the rounded forms now characterizing our uplands and lower ranges of hills and mountains2 and it is estimated that1 e4 g41 the general level of the drainage basin of the ,mississippi river is lowered about one foot in #g1jjj years1 the material being carried into the lowlands and the sea4 ,,chapter ,,ii4 ,,the ,,chemical ,,processes ,,of ,,soil ,,formation4 ,chemical ,disintegration1 or ,decomposition4 ,it may be said that in general1 the physical agencies of disintegration are most intensely active in the dry or arid regions of the globe1 while chemical processes of decomposition are most active in humid climates4 ,the chemical decomposition of rocks is primarily due to the action of the atmosphere1 the average composition of which may be stated as follows3 ,,volume ,,per ,,cent4 ,,weight ,,per ,,cent4 ---------------------------------------- ------------------------ ,nitrogen #gh4jj #ge4ee ,oxygen #ba4jj #bc4bb ,carbonic dioxid 4#jc-4jd 4#jde-4jfj ,ammonia #a to #d millionths ,water vapor ,variable2 #dh to #hc grams per cubic meter1 when saturated between ,o and #ej;,c4 ---------------------------------------- ------------------------ ,in addition to the above1 air contains minute amounts of the very indifferent and therefore practically negligible elements1 argon1 krypton1 neon1 xenon and helium1 the aggregate amount of which in air is somewhat less than one per cent1 of which the greater part is argon4 ,so far as known these elements take no part whatever in vegetable or animal life1 and possess no known chemical action or affinity4 ,the primary active agents in effecting chemical changes in rocks by which soils are formed1 are water1 carbonic acid1#h and oxygen2 all therefore ingredients of the atmosphere4 ,hence the chemical changes so brought about are in the most general sense comprehended within the term weathering1 as applied to rocks2 while the corresponding but more complex action within the soil itself is usually termed fallowing4 #h ,owing to the universal presence of water 7,h,o7 in air as well as in soils1 it is usual and convenient to speak of carbonic dioxid 7,,co7 gas when so occurring as carbonic acid 7,h,,co71 of which it produces the effects 7,,co ,h,o ,h,,co74 ,effects of ,water4--,since but few substances1 particularly among those forming rocks1 are totally insoluble even in pure water1#i and some 7such as gypsum7 may be considered easily soluble in the same1 the rain water must exert solvent action wherever it penetrates4 ,in nature1 however1 strictly pure water does not occur1 it being difficult to obtain it even artificially4 ,among the 8impurities0 almost always contained in natural water1 there are several that materially increase its solvent power4 ,foremost among these1 both because almost universally present and on account of its great ultimate efficacy1 is ,carbonic dioxid1 in contact with water forming carbonic acid1 the acidulous ingredient of all effervescent waters1 the gas which is produced in nature by innumerable processes1 such as decay1 putrefaction1 fermentation1 the slow or rapid combustion of vegetable and animal substances1 such as wood1 charcoal and all other fuels2 by the respiration of animals2 in the burning of limestone1 etc4 ,it is therefore of necessity contained in air1 on an average to the extent of about #a-cjjj of its bulk in the general atmosphere1 but locally in considerably higher proportions because of proximity to sources of formation1 and of its greater density as compared with air 7#a as against #a74 ,it may thus accumulate in inhabited buildings1 in cellars1 wells1 mines1 caves2 and it is contained in considerable proportion in the air of the soil4 ,moreover1 being easily soluble in water 7to the extent of an equal volume at the ordinary temperature and barometric pressure7 it is contained in all natural water1 whether of rains1 rivers1 springs or wells1 and largely of course in that percolating the soil4 ,such waters may therefore be considered as being acid solvents2 and as such1 they exercise a far more energetic and far-reaching effect than would pure water4 #i ,see ,chapter #ah4 ,carbonated water a universal solvent4--,while limestones are the rocks most obviously acted upon by carbonated water1 few if any resist it altogether4 ,even quartz rocks of the ordinary kinds are attacked by it2 only the purest white crystalline quartzite may be considered as sensibly proof against it4 ,granite and the rocks related to it are rather quickly acted upon1 because of the presence of the feldspar minerals containing potash1 soda and lime as bases#aj together with alumina4 #aj ,the increase of solvent power on feldspar when carbonated instead of distilled water is used1 was well exemplified in an experiment made by ,headden 7,bull4 #fe1 ,color4 ,exp't ,sta41 p4 #bi71 who allowed pure distilled and carbonated water respectively to act on fresh but finely pulverized feldspar1 with frequent shaking1 for five days4 ,the distilled water dissolved 4#jjha gram1 the carbonated water1 4#jgbc gram of solids1 or nearly nine times as much as the distilled water4 ,both residues gave strong reactions for potash with platinic chlorid4 ,the results of this action are highly important2 one being the formation of clay1 so essential as a physical ingredient of soils2 the other the setting-free of potash1 one of the most essential nutrients of plants4 ,hornblende and the related minerals are similarly acted upon so far as they contain the same substances4 ,in all cases1 of course1 the silica 7silicic acid7 set free by the carbonic acid remains partially or wholly in the resulting soils1 as such4 ,lime also at first mostly remains behind in the form of the carbonate2 but potash and especially soda compounds1 being mostly readily soluble in water1 are largely carried away by the latter4 ,the effect of carbonated water upon silicate minerals is greatly increased by the presence of ammonia 7ammonic carbonate71 which always exists in atmospheric water to a greater or less extent4 ,this effect may readily be noted on the windows of stables1 or other places where animal offal decays1 by the dimming of the glass surfaces2 also in glass bottles containing solution of ammonic carbonate4 ,action of ,oxygen4--,the effects of atmospheric oxygen on rocks are of course confined to those containing substances capable of farther oxidation4 ,chief among these are ferrous 7iron monoxid7 and ferroso-ferric oxid the latter imparting bottle-green1 bluish and black tints to so many minerals and rocks that these colors may usually be taken as indicating its presence4 ,by taking up more oxygen the ferrous and ferroso-ferric oxids are converted into ferric oxid or its hydrate 7rust71 the tints mentioned passing thereby into brick-red or rust color1 according as the former or the latter 7or sometimes their intermixtures7 is formed4 ,in either case there is an increase in bulk2 and this when taking place in the cracks or crevices of minerals or rocks1 tends1 like the freezing of water1 to widen the cracks and thus to increase the surface exposed to attack4 ,since ferrous compounds1 when soluble in water1 are injurious to plant growth1 this oxidation is of no little importance1 and in soils must be carefully maintained against a possible reversal4 ,it is hardly necessary to insist that the action of all these chemical agents continues in the soils themselves1 and that owing to the fineness of the material1 resulting in an enormously increased surface exposed to attack1 such action acquires increased intensity4 ,this is the more true as in soils bearing vegetation there are always superadded the effects of the humus-acids resulting from the decay of vegetable matter1 as well as of the acid secretions of the living plants4 ,action of ,plants and their ,remnants in ,soil ,formation4 7a7 ,mechanical action4--,the direct action of plants in forcing their roots into the crevices of rocks and minerals and thus both widening them by wedging1 and by exposing new surfaces to weathering1 has already been alluded to4 ,that the mechanical force exerted by root growth is very great1 may readily be judged from their effects in forcing apart1 even to rupture1 the walls of rock crevices2 but actual measurement has shown the force with which the root1 e4 g41 of the garden pea penetrates1 to be equal to from seven to ten atmospheres1 say from #bjj to over #cjj pounds per square inch4 ,such a force1 exerted under the protection of the corky layer protecting the root tips1 often produces surprising effects4 7b7 ,chemical action4--,vegetation takes a most important part1 from a chemical point of view1 both in the first formation of soils and in their subsequent relations to vegetable life4 ,the lower forms of vegetation are usually the first to take possession of rock surfaces2 foremost among these are the lichens4 ,in humid climates we find these crust-like plants incrusting more or less all exposed rock surfaces1 sometimes with a solid mantle that can be peeled off in wet weather1 showing the corroded rock-surface1 and the beginnings of soil clustering amid the root-fibrils beneath4 ,a microscopic examination of the substance of these lichens often shows as a prominent ingredient1 crystals of oxalate of lime1 the lime having of course been derived from the rock1 while the oxalic acid has been formed by the plant and used in the corrosion of the rock minerals4 ,when it is remembered that this acid is comparable in strength to hydrochloric and nitric acids1 the energy of the attack of the lichens is explained4 ,its progress can often be traced1 even beyond the visible root fibers1 by a change in the color of the rock2 e4 g41 from rust-color to brick red4 ,when by the action of the lichens a certain depth of loosened rock or half-formed soil has been produced1 the next step is usually the advent of various mosses1 which gradually shade out the crust-like lichens1 while the erect kinds persist for some time4 ,eventually the mosses1 after having increased still farther the soil layer on the rock surface1 are themselves partially or wholly displaced by the hardier species of ferns2 and with these the higher flowering plants1 such as the stonecrops and saxifrages 7the latter deriving their name from their 8rock-breaking0 effect71 the heather1 and many other or shallow-rooted plants1 gradually take possession4 ,the roots of all plants secrete carbonic acid2 and many of them1 much stronger vegetable acids1 such as oxalic and citric4 ,in the crevices of rocks we commonly find the roots forming a dense network over the surfaces1 the marks of which show plainly the solvent effect produced on the rock by the root secretions4 ,this is most readily observable on a polished marble surface1 or on feldspathic rocks4 ,of course the progress of soil-formation is very much more rapid when1 as in the case of powdered lava 7volcanic ash7 and rock debris resulting from the effects of frost etc41 the surface is very much increased4 ,in tropical climates1 where both vegetative and chemical action is most intense1 it takes some of the higher plants only a few years after a volcanic eruption to take possession of portions of the 8ash0 surfaces2 thus helping to form a soil on which after a few more years agricultural plants such as the vine and olive yield paying returns4 ,to this direct action of the higher plants is always added1 to a greater or less extent1 that of innumerable bacteria1 as well as molds2 whose vegetative and secretory action materially assists that of the roots1 and the weathering process in general4 ,humification4--,while the mechanical action of the roots and the chemical effect of the acids of their root secretions are very efficient in promoting the transformation of mere rock powder into soil material proper1 the efficacy does not end with the life of the plant4 ,in the natural process of decay to which the roots are subject after death1 and which also affects the leaves1 twigs and trunks falling on the surface1 the vegetable matter suffers a transformation which must be considered more in detail hereafter1 and results in the formation of the complex mixture of dark-tinted substances known as vegetable mold or humus2 the remnant of vegetation that imparts to surface soils their distinctive dark tint4 ,its functions in soils are both numerous1 and important to vegetable growth2 as regards soil formation1 it assists disintegration of the rock minerals both by the formation of certain fixed1 soluble acids capable of acting on them with considerable energy1 and by the slow but continuous evolution of carbonic acid under the influence of atmospheric oxygen1 which has been alluded to above4 ,causes influencing chemical action and decomposition4--,the chemical processes causing rock decomposition are of course continued in the soil1 and there also are materially influenced by climatic and seasonal conditions1 which bring about great differences in the kind and intensity of chemical action4 ,within the ordinary limits of solar temperatures it may be said that1 other things being equal1 the higher the temperature the more intense will be chemical action in soil formation4 ,since1 however1 water is a potent factor in the majority of these processes1 the presence or absence of moisture at the same time with heat will cause material differences in the kind and intensity of chemical action4 ,in view of the importance of carbonic acid as a chemical agent1 the presence or absence of vegetable matter or humus1 from which by oxidation or decay carbonic and humus-acids are formed1 will likewise be of material influence4 ,the presumption that climatic and seasonal conditions must greatly influence both the kind and rapidity of the soil-forming processes1 is fully borne out by observation and practice4 ,especially is the amount and distribution of rainfall of great importance in this respect1 and should therefore be first considered4 ,,influence ,,of ,,rainfall ,,on ,,soil ,,formation2 ,,leaching ,,of ,,the ,,land4 ,in the general consideration of the soil-forming processes1 it has been stated that soils formed by the disintegration of rocks 8in place10 i4 e41 without removal from the original locality1 are also designated as 8residual02 meaning thereby that only a portion of the original rock remains to form the soil mass1 while another portion has been removed4 ,to a slight extent this removal occurs by the partial washing-away of the finest clay and silt particles2 but the most important action from the agricultural point of view is the removal by leaching with the carbonated water of the atmosphere and soil1 of certain easily-soluble compounds formed in the process of chemical decomposition of rocks and resultant soils4 ,the nature of these compounds is exemplified in the subjoined table giving the composition of some waters flowing from drains in unmanured fields1 laid at depths of from two to three feet2 and for comparison with these1 the composition of the water of some of the world's large rivers1 showing what these largest drains carry into the ocean4 ,the analyses have in all cases1 where necessary1 been recalculated to parts per million1 and to oxids1 from the published data4 ,the letter 8c0 indicates that the preceding figure has in the absence of a direct determination been stoichiometrically calculated from the data given1 in order to complete the comparison4 ,,composition ,,of ,,drainage ,,waters ,,from ,,unmanured ,,ground4 7,,parts ,,per ,,million47 ,,rothamsted4 ,,proskau4 ,,mockern4 7,,voelker47 7,,krocker47 74 ,,wolff47 --------------------------------------- ,rye ,meadow4 ,field4 ---------------------------------------- ------------------- ,potash1 ,k,o #a4g #e4d #b4j #b4j #h4e #c4d ,soda1 ,na,o #f4j #aa4g #ae4a #ac4g #bc4c #h4b ,lime1 ,ca,o #ih4a #abd4c #acc4j #aah4a #abb4f #bb4e ,magnesia1 ,mg,o #e4a #f4d #cc4c #bb4d #ad4i #f4g ,iron ,oxid1 ,fe,o #e4g #d4d #f4f #f4f ,alumina1 ,al,o #h4j #f4j ,silica1 ,si,o #aj4i #ae4d #g4j #f4j #g4j #d4j ,carbonic ,acid1 ,,co #dh4a #dd4d #ge4h #hb4f #aba4c ,phos' ,acid1 ,p,o 4#fc #i4a ,trace4,trace4,trace4 #ai4j ,sulfuric ,acid1 ,,so #bd4g #ff4c #abb4g #fg4c ,chlorin1 ,cl #aj4g #aa4a #d4h #d4b #ad4j ,trace4 ,nitrogenas1 ,n,o #c4ij #e4aj ,nitrogenas1 ,,nh 4#ab 4#ac ---------------------------------------- ------------------- ,total ,mineral ,matter #bae4i #bie4e #djj4c #cbb4i #aih4c #aia4a ,less ,o3 ,cl #b4ce #b4d #a4a 4#i #c4a ,corrected ,total #bac4c #bic4a #cii4b #cbb4j #aie4b #aia4a ,organic ,matter #bb4i #ai4c #be4j #af4j #bf4j #bf4j ---------------------------------------- ------------------- ,total ,solids #bce4b #cab4d #dbd4b #cch4j #bba4b #bag4a ---------------------------------------- ------------------- ,farnham4 ,munich4 7,way47 7,zller47 ---------------------------------- ,wheat ,hop ,lysemeter ,average4 ,field4,field4 ,drainage4 ---------------------------------------- -------------- ,potash1 ,k,o ,trace4,trace4 #f4e #b4d #c4b ,soda1 ,na,o #ad4c #de4g #g4a #e4f #ae4a ,lime1 ,ca,o #fi4c #ahe4j #ade4h #eg4f #ajg4f ,magnesia1 ,mg,o #i4g #ce4a #bj4e #h4i #af4c ,iron ,oxid1 ,fe,o 4#a #f4c ,alumina1 ,al,o #e4i #g4a ,silica1 ,si,o #a4ce #ab4a #aj4d #aa4c ,carbonic ,acid1 ,,co ,phos' ,acid1 ,p,o ,trace4 #a4g #b4b,trace4 #j4e ,sulfuric ,acid1 ,,so #bc4e #ace4h #ag4e #bg4a #fj4h ,chlorin1 ,cl #aj4j #cg4d #eg4e #i4e #ag4g ,nitrogenas1 ,n,o #ajb4d #afc4e ,nitrogenas1 ,,nh 4#be 4#jc ---------------------------------------- --------------- ,total ,mineral ,matter #bdh4h #fbc4e #bfg4fabh4g ,less ,o3 ,cl #b4b #h4b #ab4g #b4ad ,corrected ,total #bdf4f #fae4c #bed4iabf4f #bhe4g ,organic ,matter #ajj4j #aje4g #bj4e #ab4f ---------------------------------------- --------------- ,total ,solids #cdf4f #gba4j #bge4daci4b #ceb4f ---------------------------------------- --------------- ,,composition ,,of ,,river ,,waters4 ,,parts ,,per ,,million4 ,yukon1 ,dwina1 ,st4 ,lawrence1 ,missouri1 ,alaska4 above ,pointe des ,montana4 ,archangel4 ,cascades4 ---------------------------------------- ------------------------- ,potash1 ,k,o ,trace #ab4eh #a4dj #a4ij ,soda1 ,na,o #h4aj #bc4ch #f4ij #cj4aj ,lithia1 ,li,o ,lime1 ,ca,o #cj4dj #cg4cj #de4cj #eh4jj ,magnesia1 ,mg,o #g4cj #cf4be #i4gj #ah4aj ,manganese1 ,mn,o ,ferric ,oxid1 ,fe,o #a4fc #c4aj ,alumina1 ,al,o #a4hj ,silica1 ,si,o #g4fj #c4je #cb4fj #ah4ij ,carbonic ,acid1 ,,co #cc4jj #ed4ja #fh4dj #fe4bj;c ,phosphoric ,acid1 ,p,o 4#dj ,trace 4#bb ,nitric ,acid1 ,n,o ,sulfuric ,acid1 ,,so #h4ej #bi4fb #dg4gj #ba4ij ,chlorin1 ,cl 4#dj #cc4ji #b4dj #ah4jj;c ,ammonia1 ,,nh ----- ------ ------ ------ ,total ,mineral ,matter #ig4aj #bca4ca #bad4dj #bbe4db ,less ,o 3 ,cl 4#aj #g4cc 4#ee #d4aj ----- ------ ------ ------ ,corrected ,totals #ig4jj #bbc4ih #bac4he #bba4cb ,organic ,matter ----- ------ ------ ------ ,total ,solids #ig4jj #bac4he #bba4bb ---------------------------------------- ------------------------- ,f4 ,w4 ,c4 ,t4 ,s4 ,clarke1 ,schmidt1 ,hunt1 ,traphagen1 ,jour4 ,am4 ,jahresb4 ,geol4 of ,bull4 ,mont4 ,chem4 ,soc4d4 ,chemie1 ,canada1 ,expt4 ,sta4 ,feb4 #aije1 #ahgc4 #ahfc4 ,no4 #aij4 p4 #aab4 ---------------------------------------- ------------------------- ,mississippi near ,carrollton1 ,la4 ,average of one year4 ---------------------------------------- - ,min4 ,max4 ,may #aije4 ---------------------------------------- ---------------------- ,potash1 ,k,o #b4hj ,soda1 ,na,o #ai4hj;c #ac4ej ,lithia1 ,li,o ,lime1 ,ca,o #di4ge ,dec4 #cc4ha ,feb4 #da4bj ,magnesia1 ,mg,o #dj4hjaf4ci ,march #aj4cb ,feb4 #aa4cj ,manganese1 ,mn,o #ab4dj 4#af ,ferric ,oxid1 ,fe,o #b4aj 4#aa ,alumina1 ,al,o 4#ag ,silica1 ,si,o #h4gjaa4de ,march #e4id ,april #g4dj ,carbonic ,acid1 ,,co #de4aj #cc4af;c ,phosphoric ,acid1 ,p,o 4#cc ,nitric ,acid1 ,n,o 4#ac 4#bc ,sulfuric ,acid1 ,,so #af4aj #bd4gb ,july #h4ah ,jan4 #bc4ij ,chlorin1 ,cl #i4fja #d4ej ,june #f4ij ,dec4 #af4aj ,ammonia1 ,,nh 4#af ---------------- ---------- ------ ,total ,mineral ,matter #aed4gc #aej4eb ,less ,o 3 ,cl #b4aj #c4fc ---------------- ---------- ------ ,corrected ,totals #aeb4fc #ahj4j ,july #aaj4j ,dec4 #adf4hi ,organic ,matter ---------------- ---------- ------ ,total ,solids #aeb4fc #adf4hi ---------------------------------------- ---------------------- ,porter1 ,stone1 ,rep4 ,new ,orleans ,u4 ,s4 ,sewerage and ,water ,reclamation ,board4 ,service4 ---------------------------------------- ------------------------ ,rio ,grande1 ,average ,average ,ft4 ,craig1 ,nile near ,cairo4of the #gai ,great ,n4 ,m4 rivers4,rivers of the ,world4 ---------------------------------------- ---- ,high4 ,low4 ,aug4 ,may #ac1 #ahgd4 #ahge4 ---------------------------------------- ------------------------- ,potash1 ,k,o 4#hj #ae4ja #d4jd #d4hj #b4dj ,soda1 ,na,o #dc4dj #e4hg #ac4ja #ah4bj #g4aj ,lithia1 ,li,o 4#bj ,lime1 ,ca,o #bb4hj #dd4bb #ea4gh #dc4ej #dc4bj ,magnesia1 ,mg,o #b4aj #aj4cc #aj4bi #ac4aj #ad4gj ,manganese1 ,mn,o #a4bj ,ferric ,oxid1 ,fe,o #a4hj #b4hj ,alumina1 ,al,o #a4hj #c4aj ,silica1 ,si,o #aa4bi #f4ga #aj4hj #af4dj ,carbonic ,acid1 ,,co #aj4be #db4ha #dj4ia #ch4aj #df4jj ,phosphoric ,acid1 ,p,o 4#bd 4#cj ,nitric ,acid1 ,n,o 4#ah #c4hj ,sulfuric ,acid1 ,,so #dg4jj #ah4cg #bi4ca #bf4ij #h4jj ,chlorin1 ,cl #cf4jj #f4bh #ag4cg #ae4ej #c4gj ,ammonia1 ,,nh 4#jdc 4#jad 4#jg ------ ------- ------- ------ ------ ,total ,mineral ,matter #afb4ce #aed4bbc #agc4dcd #agc4ab #aeb4ig ,less ,o 3 ,cl #h4je #a4dj #d4ac #c4ej 4#gb ------ ------- ------- ------ ------ ,corrected ,totals #aed4cj #aeb4hbc #afi4cjd #afi4fb #aeb4be ,organic ,matter #af4d ------ ------- ------- ------ ------ ,total ,solids #aed4cj #afd4fhc #bjj4eid #afi4fb #afh4fe ---------------------------------------- ------------------------- ,o4 ,loew1 ,john ,u4 ,s4 ,letheby1 ,jour4 ,murray1 ,geogr4 of the ,khediv4 ,scottish ,survey ,agr4 ,society4 ,geogr4 ,w4 of ,mag41 #ajjth ,vol4 #c1 ,merid4 #ahhg4 ,vol4 #c4 ---------------------------------------- -------------------------- ,it will be noted that in all the drain waters1 lime is the ingredient most abundantly leached out1 and as reference to the acids shows1 mainly in the form of carbonate1 also in that of sulfate4 ,magnesia is next in amount among the bases2 next in amount is soda1 largely in the form of sodium chlorid or common salt4 ,potash is present only in small but rather uniform amounts4 ,of the acids the carbonic is the most abundant1 sulfuric next2 chlorin and silicic acid come next1 in about equal amounts4 ,nitric acid passes off in small1 but still relatively considerable amounts4 ,comparison of the drain waters with the river waters1 while showing a general qualitative agreement1 also shows a marked diminution of total solids 7from #bhe4g to #ahh4g2 hence 8soft river water071 and especially of lime 7from #ajg4f to #dc4b71 together with the carbonic acid with which it is mostly combined2 indicating a deposition of lime carbonate in the river deposits or alluvial lands4 ,there is1 on the other hand1 little if any general difference in the magnesia content of the two classes of waters2 nearly the same is true of soda1 so that these two bases really show a considerable relative increase when the diminished total is considered4 ,potash remains about the same all through1 viz4 two parts or a little more2 phosphoric acid shows a fraction of one millionth2 nitric acid varies greatly but is usually higher in the drain waters1 sometimes showing a heavy depletion of the land by the leaching-out of this important plant food4 ,it has been computed by ,john ,murray1 as quoted by ,russell1#aa that the volume of water flowing into the sea in one year1 including all the land areas of the earth1 is about #febd cubic miles4 ,from the average composition of river waters as given above1 it would follow that nearly five billions 7#d1ige1aag1ehh7 of tons of mineral matter are annually carried away in solution from the land into the sea4 ,the amount of sediment carried at the same time is many times greater2 in the case of the ,mississippi river1 it is more than five times the amount of the matter carried in solution4 #aa ,rivers of ,north ,america1 p4 #hj4 ,comparison of the river waters among themselves shows less of any consistent relation to climatic conditions than might have been anticipated4 ,the waters of the arctic streams ,yukon and ,dwina show wider differences than any two other waters in the list1 unless it be the ,st4 ,lawrence1 another northern stream4 ,the ,missouri and ,rio ,grande show by their high content of soda1 chlorin and sulfuric acid their origin in arid climates1 where alkali lands prevail4 ,the water of the ,nile is here represented by two analyses1#ab one showing the season when the water is 8red0 and of high fertilizing quality because of the sediment it brings down from the mountains of ,abyssinia2 the other the 8green0 and relatively clear water which comes from the great lakes and through the 8sudd 0 or grassy swamp region near the junction of the ,gazelle river with the ,nile4 ,of the analyses given of the ,mississippi river water1 the first represents the average of a full year's observations made weekly under the auspices of the ,new ,orleans ,commission on ,sewerage and ,drainage1 by ,j4 ,l4 ,porter4 ,the fourth is an analysis made of water taken at the same point in ,may1 #aije2 the analysis having been made in full by ,mr4 ,stone1 of the ,reclamation ,service of the ,u4 ,s4 ,geol4 ,survey1 the direct determination of potash and soda being in this case included4 ,as will be seen1 and might be expected1 the average of the ,mississippi water corresponds quite nearly to that of nineteen of the world's great rivers as given by ,murray4 ,the very great variation in the content of sulfates is evidently due to the occasional heavy influx of the gypseous waters of the ,washita and ,red rivers when in flood2 while the minimum content 7in ,january7 agrees almost precisely with the general average4 ,murray's table would hardly be changed if these analyses of ,mississippi water were incorporated therein1 owing doubtless to the large and varied drainage area of the great river4 #ab ,the correctness of ,letheby's analyses has been disputed1 partly because of their disagreement with former analyses in the very high amount of lime1 partly because of the high potash-content in the ,low-,nile water4 ,the lime content is1 however1 confirmed by the partial analyses made by ,mathey in #ahhg1 which gives an average of #dd4a for the year1 while the older analyses1 made in ,europe1 of transported water gave only half as much4 ,letheby working on the spot was doubtless more nearly right in this respect4 ,his figure for potash in the 8,low-,nile0 water agrees with former determinations1 but that in the 8,high-,nile0 is approached only by that in the ,dwina water4 ,it may be suspected that the soda is too low and potash too high in this analysis4 ,sea ,water4--,the nature of the substances permanently leached out is also seen by considering the composition of sea water1 since the ocean is the final reservoir for all the leachings of the land4 ,it might be objected that the ocean may have received its salts from other sources2 but this objection is overborne by the fact that substantially the same salts are found in landlocked lakes1 in which1 as they have no outflow1 the leachings of the adjacent regions are perforce1 as a rule1 the only possible source of the salts4 ,it is true that the nature of the salts differs somewhat in different lakes1 as might be expected2 but a general statement of that nature will1 after all1 be the same as that made in regard to sea-water4 ,the following table of the average composition of sea-water1 according to ,regnault1 illustrates these facts4 ,,mean ,,composition ,,of ,,sea-,,water4 ,sodium ,chlorid 7common salt7 #b4gjj ,potassium chlorid 4#jgj ,calcium sulfate 7gypsum7 4#adj ,magnesium sulfate 7,epsom salt7 4#bcj ,magnesium chlorid 7bittern7 4#cfj ,magnesium bromid 4#jjb ,calcium carbonate 7limestone7 4#jjc ,water 7and loss in analysis7 #if4die ------- #ajj4jjj ,the average saline contents of sea-water would thus be #c4eje per cent ,in twenty-one determinations of the saline contents of the ,atlantic ,ocean1 the percentage ranged from #c4ejf to #c4gaj per cent ,of this mineral residue1 common salt constitutes from about #ge to over #hj per cent4 ,we see that most prominent among the ingredients mentioned here is common salt 7sodium chlorid71 which forms nearly four-fifths of the total solid contents4 ,next in quantity are the compounds of magnesium1 viz4 ,epsom salt and bittern1 with a very small amount of the bromin compound4 ,next come the compounds of calcium 7lime71 of which gypsum is the more abundant1 while the carbonate1 so abundant on the land surface in the various forms of limestone1 is present in minute amounts only1 yet enough to supply the substance needed for the shells of shellfish1 corals1 etc4 ,least in amount of the metallic elements mentioned is potassium4 ,calculating the total amounts of chlorin1 we find that it exceeds in weight any one other element present in the salts of sea-water1 being two-sevenths of the whole solids4 ,substantially the same result1 with variations due to local causes1 as exemplified in the varying composition of river and drain waters1 is obtained when we consider the saline ingredients of lakes having no outlet1 and in which therefore1 the leachings of the tributary land area have accumulated for ages4 ,the ,great ,salt ,lake of ,utah1 the landlocked lakes of the ,nevada basin1 of ,california1 ,oregon1 and of the deserts of ,asia1 ,africa1 and ,australia1 all tell the same tale1 which may be summarized in the statement that the chlorids of sodium and magnesium1 and the sulfates of sodium1 magnesium and calcium constitute the bulk of the leachings of the land2 while of other substances potassium alone is present in relatively considerable amount4 ,while the above analysis shows the ingredients of sea-water so far as they can at present be directly determined by chemical analysis1 yet the presence of many others is demonstrable1 directly or indirectly1 from various sources4 ,one is1 the mother-waters from the making of sea-salt1 in which such substances accumulate so as to become ascertainable by chemical means1 and even become industrially available in the cases of potash and bromin4 ,another is the ash of seaweeds1 which is indisputably derived from the sea-water1 and contains1 among other substances not directly demonstrable in the original water1 notable quantities of iodin 7of which this ash is a commercial source71 iron1 manganese1 and phosphoric acid4 ,again1 the copper sheathing of vessels1 as it is gradually corroded1 becomes more or less rich in silver1 manifestly thrown down from the sea-water1 and the silver so obtained is associated with minute amounts of gold4 ,copper1 lithium1 and fluorin likewise have been found in sea water2 and it is probable that close search would detect very many of the other chemical elements as ordinary ingredients in minute amounts4 ,this is what must be expected from the fact that few mineral substances known to us are entirely insoluble in pure water1 and still fewer in water charged with carbonic acid4 ,the latter is always present in sea-water and holds the lime carbonate in solution2 on evaporation or boiling1 this substance is the first to be precipitated2 and thin sheets of limestone from this source are commonly found at the base of rock-salt beds1 which1 themselves1 are evidently the result of the evaporation of segregated bodies of sea-water in past geological ages4 ,summing up the facts concerning the water of the sea and of landlocked lakes1 with reference to the ingredients of soils needful for the nutrition of plants1 it appears that the rock ingredients leached out in the largest amounts 7lime alone excepted7 are those of which the smallest quantities only are required by most plants2 while of those specially needful for plant nutrition1 only potash is removed in practically appreciable amounts by the stream drainage4 ,result of insufficient ,rainfall2 ,alkali ,soils4--,when the rainfall is either in total quantity1 or in consequence of its distribution in time1 insufficient to effect this leaching1 the substances that otherwise would have passed into the drainage and the sea are wholly or partially retained in the soil2 and when the rainfall deficiency exceeds a certain point1 the salts thus retained may become apparent on the surface in the form of saline efflorescences1 or as it is usually termed in ,north ,america1 8alkali40#ac ,their continued presence modifies in various ways the process of soil formation and the nature of the soils as compared with those of regions of abundant rainfall 78humid climates072 one of the most prominent and important results being that1 besides the easily soluble salts mentioned above1 the carbonate of lime formed in the process of decomposition is also retained1 and imparts to the soils of regions of deficient rainfall 78arid climates07 the almost invariable character of calcareous lands4 ,there is thus in the ,united ,states a marked and practically very important contrast between the soils of the arid region west of the ,rocky ,mountains and those of the 8humid0 region between the immediate valley of the ,mississippi and the ,atlantic coast4 ,these differences and their practical bearings can be best discussed after first considering more in detail the chemical decomposition of the several soil-forming minerals4 #ac ,in some cases the soluble salts originate in rocks impregnated with salts from marine lagoons or landlocked lakes1 or directly from their evaporation residues4 ,but this is the exception rather than the rule4 ,,chapter ,,iii4 ,,the ,,major ,,soil-,,forming ,,minerals4 ,since the several stratified rocks1 such as sandstones1 shales1 claystones1 clays1 limestones1 etc41 are themselves but the outcome of the same disintegrating and decomposing influences upon the crystalline rocks by which soils are now formed1 we must study the action of these influences upon the minerals composing the latter rocks in order to gain a comprehensive understanding of the subject4 ,while the number of different minerals known to science is very large1 such study need not go beyond a small number of the chiefly important1 rock-forming species which are so generally distributed as to require consideration in this connection4 ,these minerals are the following3 ,quartz and its varieties2 the several feldspars2 hornblende and augite2 the micas2 talc and serpentine4 ,calcite1 gypsum and dolomite1 though not contained in the older rocks1 must be considered because of their forming large rock deposits by themselves2 and zeolites require mention because1 though rarely forming a large proportion of rocks1 they are of special importance as soil ingredients4 ,quartz and the minerals allied to it consist essentially of dioxid of silicon1 usually without 7quartz proper7 but partly also with water in combination 7opal and its varieties74 ,silicon is next to oxygen the most abundant element found on the earth's surface4 ,it occurs largely in the various forms of quartz1 alone1 or as one ingredient of compound rock-masses2 the rest1 in combination 7as silica7 with various metallic oxids1 forms the important group of silicate minerals1 constituting the bulk of most rocks4 ,quartz occurs frequently in crystals 7rock crystal2 six-sided prisms terminated by six-sided pyramids71 clear or variously colored2 but more abundantly as quartz rock or quartzite1 readily known by its hardness1 so as to strike fire with steel1 and by its glass-like1 irregular fracture4 ,besides the crystalline quartz rock we find close-grained and at least partly non-crystalline varieties1 such as hornstone and flint4 ,sandstones most commonly consist of grains of quartz cemented by some other mineral1 or by silica itself2 in the latter case the siliceous sandstone frequently passes insensibly into true quartzite4 ,the loose sand so well known to common life is prevalently composed of quartz grains1 whose hardness and resistance to weathering enables them to survive longest the soil-forming agencies4 ,quartz and its allied rocks--jasper1 hornstone1 siliceous schist1 etc41 are all1 as already stated1 acted on with difficulty by the 8weathering0 agencies4 ,crystalline quartz rock may be considered as practically refractory against all but the mechanical agencies1 and hence remains in the form of sand and gravel1 more or less rounded by attrition1 as a prominent component of most soils2 sometimes to the extent of over #ib per cent1 even in soils highly esteemed in cultivation1 especially in the arid region4 ,such soils are mostly the result of the disintegration of sandstones1 the cement of which has been dissolved out in the course of weathering2 or they may be derived directly from geological deposits of more or less loose and unconsolidated sand4 ,among crystalline rocks1 granites1 gneiss and mica-schists are those most usually concerned in the formation of sandy soils2 since in common parlance1 quartz is understood to be the substance of the sand unless otherwise stated4 ,the exceptions are especially important in the regions of deficient rainfall4 ,but while crystalline quartz is practically insoluble in all natural solvents1 the same is not true of the jaspers and hornstones4 ,these consist of a mixture of crystalline and amorphous 7non-crystalline7 silica1 which is more readily soluble than the crystalline1 and is attacked by many natural waters1 especially by those containing even very small amounts of the carbonates of potash or soda4 ,we thus often find that hornstone and jasper pebbles buried in the soil1 while still hard internally1 have externally been converted into a friable1 almost chalky substance1 consisting of crystalline quartz from which the cementing amorphous silex has been removed by the soil water4 ,in the course of time such pebbles may be completely destroyed by this process1 so as to be light and chalky throughout1 and readily crushed in tillage4 ,the change is the more striking when1 as frequently happens1 the hornstone pebble is traversed by small veins of crystalline quartz1 which remain as a skeleton4 ,solubility of ,silica in ,water4--,it is easily shown experimentally that the compound of silica with water 7hydrate7 is under certain conditions readily soluble not only in pure water1 but also in such as contains carbonic acid4 ,it thus occurs in nearly all spring and well waters2 some hot springs deposit large masses of it 7sinter72 and geological evidence clearly demonstrates that quartz veins have as rule been formed from water-solutions of silica4 ,that silica in its soluble form circulates freely in the soil water1 is abundantly evident from the large amounts of it which are secreted on the outside of the stems of grasses1 horsetail rushes and other plants1 imparting a gritty roughness to their outer surface4 ,in the case of the giant bamboo grass of ,asia1 the silica accumulated on the outside of the joints forms a hard sheath of considerable thickness1 known to commerce as tabashir4 ,that among the first products of rock decomposition we often find small amounts of the silicates of the alkalies 7potash and soda7 has already been mentioned4 ,it cannot be doubted that the same continues to be formed in soil containing the proper minerals2 and there they also take part in the formation of the easily decomposable hydrous silicates designated as zeolites1 which are largely instrumental in retaining the 8reserve0 of mineral plant-food in soils4 ,,silicate ,,minerals4 ,silica occurs in nature combined with the oxids of most metals1 forming silicates2 but most abundantly with the earths 7lime1 magnesia1 alumina7 and alkalies 7potash and soda74 ,these compounds are the most important in soil formation2 and among them the following are the chief3 ,the ,feldspars1 which may be defined as compounds of silicates of potash1 soda or lime 7either or all7 with silicate of alumina4 ,they are prominent ingredients of most crystalline rocks2 potash feldspar 7orthoclase7 with quartz and mica forms granite and gneiss2 feldspars containing soda and lime 7either or both7 form part of many other crystalline rocks1 such as basalt1 diabase1 diorite1 gabbro and most lavas4 ,the feldspars are decomposed by weathering rather readily1 and are important in being the chief source of clays as well as of potash in soils4 ,when acted upon by carbonated water1 the bases potash1 soda1 and lime or carbonates1 the silica being mostly displaced2 while the silicate of alumina takes up water and forms kaolinite1 the essential basis of clays1 and one of the most important constituents of soils2 imparting to them the necessary firmness and cohesion1 together with other important physical properties1 discussed more in detail hereafter4 ,while thus on the one hand feldspars are the source of clay1 on the other they supply one of the most essential ingredients of plant food1 viz4 potash2 which is first dissolved by the water in the forms of carbonate and silicate1 but in most cases soon becomes fixed in the soil by forming more complex 7zeolitic7 combinations4 ,the soda not being retained by the soil as strongly as is potash is washed through into the country drainage2 while if lime is present1 it mostly remains in the form of the carbonate4 ,orthoclase feldspar contains nearly #ag of potash2 ,leucite1 a related mineral occurring in some lavas1 contains #ba4e4 ,the other feldspars contain only a few per cent1 sometimes none4 ,other silicate minerals1 so far as they contain the same bases1 are acted upon similarly to the feldspars4 ,in the decomposition of the feldspars by carbonated water1 the compounds of potash and soda so formed are soluble in water1 those of lime and magnesia are insoluble or nearly so4 ,hence pure clays can be formed only in the decomposition of the potash-and soda-feldspars 7orthoclase1 albite7 while in the case of lime feldspar 7labradorite7 and the mixed feldspars 7plagioclase1 anorthite7 calcareous clays 7marls7 are the result4 ,lime feldspar resists decomposition more tenaciously than do those containing large proportions of the strong bases potash and soda2 potash feldspar especially is attacked most readily1 and is the main source of the formation of the valuable deposits of porcelain earth or kaolin1 which is essentially a mixture of kaolinite with fine silex and more or less of undecomposed feldspar1 and is of a chalky texture4 ,formation of ,clays4--,when instead of remaining in place1 this kaolin is washed away and triturated in the transportation by water1 it is partially changed from its original chalky condition to that plastic and adhesive form which is the characteristic ingredient of all clays4 ,the remarkable properties of this substance and the part it plays in the physical constitution of soils1 will be discussed in another chapter4 ,its lightness and extreme fineness of grain 7if grain it can be called7 cause it to be carried farther on by the streams than any other portion of the products of rock decomposition save those actually in solution2 it can therefore be deposited only in water that is almost or quite still 7as in swamps7 so long as the latter is fresh4 ,so soon however as brackish or salt water is encountered1 clay promptly gathers into floccules 78flocculates071 and thus enveloping the finest-grained silts that may have been carried along with it1 it quickly settles down1 forming the 8mud banks0 and heavy clay soils that are so characteristic of the lower deltas of rivers1 as well as of swamps formed by the backwater or overflow of the same4 ,when instead of potash feldspar alone1 the lime- or soda-lime feldspars are also concerned in the decomposition process1 the resulting clay soils will be more or less calcareous1 while the soda1 as stated above1 is for the greater part leached out permanently4 ,hornblende 7,amphibole7 and ,pyroxene 7,augite74 ,these are two very widely diffused minerals1 differing but little in composition though somewhat differently crystallized1 mostly in short columnar forms4 ,the typical and most abundant varieties of these minerals appear black to the eye1 though in thin sections they are bottle-green2 they form the black ingredient of most rocks4 ,the color is due to ferroso-ferric 7magnetic7 oxid of iron2 the mineral as a whole may be considered as a silicate of lime1 magnesia1 alumina and iron1 varying greatly in their absolute proportions2 alumina and iron being sometimes almost absent4 ,when iron is lacking the mineral may be almost white 7tremolite1 asbestos71 and its weathering is then much retarded1 since the oxygen of the air cannot take part in the process of disintegration4 ,the black variety of hornblende is not only the most abundant as a rock-ingredient1 but it also the one most easily decomposed and therefore most commonly concerned in soil formation4 ,the black hornblende owes its easy decomposition under the atmospheric influences to two properties2 one1 its easy cleavage1 whereby cracks are readily formed and extended by the agencies already mentioned 7pp4 #a-c74 ,the other is its large content of ferrous silicate 7silicate of iron protoxide71 whereby it is liable to attack from atmospheric oxygen2 the latter forms ferric hydrate 7iron rust7 out of the protoxide1 thus causing an increase of bulk which tends to split the masses of the mineral in several directions1 while the silex is set free4 ,at the same time the carbonic acid of the air converts the silicate of lime and magnesia1 which forms the rest of the mineral1 into carbonates2 and the alumina present forms kaolinite1 as in the case of the feldspars4 ,there is thus formed from this mineral1 when alone1 a strongly rust-colored1 more or less calcareous and magnesian clay1 constituting the material for rather light-textured 8red0 soils4 ,in most cases however the hornblende is associated in the rock itself with the several feldspars1 7mostly lime- and soda-lime feldspars7 as well as with more or less quartz4 ,the rust-colored soils are therefore most commonly the joint result of the weathering of these several minerals4 ,this is well exemplified in the case of the 8red0 soils formed from the so-called granites and slates of the western slope of the ,sierra ,nevada of ,california4 ,pyroxene or ,augite so nearly resembles hornblende in its chemical composition and crystalline form1 that what is said of the latter may be considered as applying to augite also4 ,owing however to the absence of any prominent tendency to cleavage1 the smooth crystals of this mineral are attacked much less readily than is hornblende1 so that we often find them as 8black gravel0 in the soils formed from rocks containing it4 ,such soils are particularly abundant and important in the region covered by the great sheet of eruptive rocks 7basalts1 so-called7 in the ,pacific ,northwest1 and on the plateau of ,south ,central ,india 7the ,deccan71 and result likewise from the decomposition of the black lavas of volcanoes2 thus in the ,hawaiian islands1 and in the ,andes of ,peru and ,chile4 ,both hornblende and augite being either free from1 or deficient in potash1 of coarse the soils formed from them are apt to lack an adequate supply of this substance for plant use4 ,this is markedly true of hornblende schist or amphibolite rocks4 ,mica1 commonly known as isinglass1 is so conspicuous wherever it occurs that it is more readily recognized than any other mineral4 ,it occurs in glittering scales in soils and sands1 and in rocks it sometimes forms sheets of sufficient size to supply the small panes for the doors of stoves1 lamp chimneys1 etc41 which being flexible are not liable to break1 but only gradually scale into very thin films1 into which it can also be split by hand4 ,when white1 7muscovite1 phlogopite7 its scales are sometimes mistaken for silver by mine prospectors2 when yellow1 for gold2 but their extreme lightness should soon remove these delusions4 ,the composition of mica is not widely different from that of the two preceding minerals2 like these it sometimes contains much iron1 and is then dark bottle-green 7biotite72 this variety in weathering becomes bright yellow1 and soon disintegrates4 ,this mineral is so abundant an ingredient of many rocks and soils1 that one naturally looks for it to play some definite or important part in soil formation4 ,by its ready cleavage it favors the disintegration of rocks2 but it seems that owing to the extremely slow weathering of its smooth1 shining cleavage surfaces1 it exerts no notable effect upon the chemical composition of the soil1 although1 owing to its peculiar character of fine scales1 it sometimes adds not immaterially to the facility of tillage in otherwise somewhat intractable soils4 ,so far as is known at present1 its presence or absence does not constitute1 in itself1 any definite cause or indication of the quality of any soil4 ,it may nevertheless be said that the rock in which it usually occurs most abundantly--mica-schist1 a mixture of mica and quartz--is known to form1 as a rule1 lands of poor quality4 ,on the other hand1 the soils derived from granites and gneisses1 even when rich in mica1 are usually excellent1 on account of their content of feldspars1 and frequently of other associated minerals4 ,hydromica differs from the preceding mainly in containing a larger proportion of combined water2 but it hardly decomposes more readily1 and the rocks in which it mainly occurs 7hydromica schists7 are refractory to weathering1 and in any case do not yield soils of any fertility1 the mineral being associated simply with quartz4 ,chlorite1 essentially a silicate of alumina and iron1 somewhat resembles mica but is deep green or black1 in small scales4 ,it forms part of certain rocks 7chlorite schists71 which greatly resemble the hornblende schists1 but are usually inferior to the latter as soil-formers1 containing but little of any direct value to plant life4 ,talc and ,serpentine1 ,hydrous silicates of magnesia1 are extensive rock-materials in some regions1 and as such require mention as soil-formers also4 ,serpentine usually forms blackish-green rock-masses1 that although soft disintegrate very slowly in the absence of definite structure1 and are attacked with some energy only when charged--as is frequently the case--with ferrous oxide4 ,the conversion of this into ferric hydrate1 so common in nature1 here also serves as the point of attack on a rock otherwise very stable2 causing it to crumble1 even though slowly4 ,talc 7the true 8soapstone07 being usually free from iron1 would be even more slow than serpentine to yield to weathering1 but that its extreme softness and ready cleavage greatly facilitate its abrasion4 ,thus talc schist1 which is usually a mixture of talc with more or less quartz1 undergoes mechanical disintegration quite readily4 ,but the soils formed from either serpentine or talcose rocks are almost always very poor in plant food1 and sometimes totally sterile4 ,magnesia1 though an indispensable ingredient of plant food1 is rarely deficient in soils and unlike lime does not influence in any sensible degree the process of soil formation4 ,magnesian rocks as a whole are practically found to be not specially desirable soil-formers1 even in the form of magnesian limestones4 ,they do not even1 as a rule1 contain as many useful accessory minerals as are commonly found in limestones4 ,moreover1 an excess of magnesia over lime is injurious to most crops1 as is shown later 7chapt4 #ah74 ,the ,zeolites4--,zeolites may be defined as hydro-silicates containing as bases chiefly lime and alumina1 commonly together with more or less of potash and soda1 more rarely magnesia and baryta4 ,the water is easily expelled by heating1 but is present in the basic form1 not merely as water of crystallization4 ,all zeolites are readily decomposed by chlorhydric and other stronger acids4 ,the zeolites proper are not original rock ingredients1 but are formed in the course of rock decomposition by atmospheric agencies1 heated water1 and other processes not fully understood4 ,they are therefore usually found in the cavities and crevices of rocks that have been subject to the influence of atmospheric or thermal waters1 most frequently in eruptive rocks1 particularly in the vesicular cavities characterizing what is known as amygdaloids4 ,they are also found in the crevices of sandstones and shales percolated by water1 as well as in nodules of infiltration 7geodes71 in which they are frequently associated with quartz4 ,those found in the cavities of rocks are usually well crystallized wherever room is afforded1 and are readily recognized by their crystalline form2 they are mostly colorless1 sometimes yellow or reddish4 ,exchange of bases in ,zeolites4--,although zeolites rarely form a large proportion of rock-masses and therefore do not enter directly into the soil minerals to any great extent1 their interest in connection with soil-formation is very great1 because of the continuation1 within the soil1 of the same processes that bring about their formation in rocks4 ,under the conditions existing in soils they will naturally rarely form crystals1 but will appear in the pulverulent or gelatinous form1 leaving the zeolitic nature of the material to be inferred from its chemical behavior4 ,among these characters the ready decomposability by acids has already been mentioned2 another of special importance in the economy of soils is the fact that when a pulverized zeolite is subjected to the action of a solution containing either of the stronger bases usually present 7potash1 soda or lime71 such base or bases will be partially or wholly taken up by the zeolitic powder1 while corresponding amounts of the bases originally present will pass into solution4 ,thus when a hydrosilicate of soda and alumina is digested with a solution of potassic chlorid or sulphate1 the soda may be partially or wholly replaced by potash1 while the corresponding sodium salt passes into solution4 ,in the case of zeolites containing lime or magnesia or both1 the action of potassic or sodic chlorid will be to partially replace the lime1 while calcic and magnesic chlorids pass into solution1 resulting in the partial or complete replacement of the lime by one or the other1 or by both bases4 ,it is important to note that1 other things being equal1 potash is usually absorbed in greater amounts and is held more tenaciously than soda4 ,the process may frequently be partially or wholly reversed again1 by subsequent treatment with large amounts of solutions of the displaced base or bases4 ,thus while a solution of potassic chlorid may be made to expel almost completely the sodium present in analcite1 subsequent treatment with sodic chlorid solution will again almost completely displace the potash before taken up4 ,the same happens when the natural mineral potash leucite1 7see p4 #cb7 of frequent occurrence in certain lavas1 is pulverized and treated with a sodic solution2 resulting finally in the production of a mass corresponding to natural analcite1 the sodium mineral corresponding to leucite4 ,in other words1 in any zeolitic powder the alkaline or alkaline earth bases present may be partially or wholly displaced by digestion with an excess of solution of any of these1 varying according to the amount of solution employed1 and the length of time and temperature of action4 ,this characteristic behavior of zeolites is exactly reproduced in soils4 ,few soils permit any saline solution to pass through them unchanged2 solutions of alkaline chlorids filtered through soils almost invariably cause the passing through of calcium and magnesium chlorids1 while a part of the alkaline base is retained2 and as a matter of fact1 we find that this absorbing power of soils for alkaline bases is more or less directly proportional to the amount of matter which may be dissolved or decomposed with elimination of silica1 by means of acids4 ,this absorption of bases from solutions by chemical fixation will be farther discussed later on2 but it should be mentioned here that both naturally and artificially1 rock-masses are very commonly cemented1 wholly or in part1 by zeolitic material4 ,hydraulic concretes may be considered as sandstones or conglomerates whose grains are cemented by a zeolitic cement consisting of silica1 lime and alumina1 with usually some potash or soda1 and of course containing the basic water2 hence unaffected by the farther action of the latter substance after the time of setting has expired1 which varies somewhat according to the nature of the material used4 ,that similar cements should occur in natural sandstones is to be expected2 thus we find not unfrequently that certain sandstones are materially softened1 and their resistance destroyed1 by treatment with even moderately dilute acid1 while silica and the usual zeolite bases pass into solution4 ,it is not often1 however1 that zeolitic material alone cements the sandstone2 it is most frequently associated with siliceous1 calcareous and sometimes even with ferruginous cementing material4#ad #ad ,a zeolitic mass1 at first gelatinous and then becoming granular-crystalline is frequently observed oozing from the lower surface of newly made concrete reservoir dams3 just as we find similar oozes consolidated into natrolite crusts in the crevices of natural sandstones4 ,,calcite ,,and ,,limestones4 ,calcite or calcareous spar is one of the minerals most commonly known in the crystallized form1 and is readily recognized by its perfect cleavage in three directions1 producing cleavage forms with smooth1 rhomb-shaped faces 7rhombohedrons72 these are sometimes colorless and perfectly transparent1 and laid on printed paper show the letters double4 ,but it may be whitish-opaque1 and of various colors1 which may also be imparted to the limestones formed from it4 ,it is readily distinguished from quartz1 which it sometimes resembles1 by its cleavage1 its inferior hardness1 being easily scratched with a knife2 and by its effervescence with acids1 the latter being the crucial test when other marks are unavailable1 as when it forms soft granular masses or 8marls40 ,in all cases it can be recognized by its crystalline form under the microscope1 even when the substance containing it has been pulverized in a mortar4 ,the great importance of this compound--calcic carbonate--from the agricultural point of view renders it desirable that it1 as well as limestones as such1 should be recognized1 when seen1 by every farmer4 ,in mass the pure mineral constitutes white marble2 colored or variegated marbles are more or less impure from the presence of other minerals4 ,some compact limestones also are nearly pure2 and as supplying only a single ingredient of plant food these would not be much better soil-formers than quartz or serpentine4 ,but it is quite otherwise with common limestones2 the mass of which1 it is true1 is formed of calc-spar1 but owing to its origin1 is in the great majority of cases so far commingled with other matters of various character1 that limestones are popularly reputed to form the very best soils4 8,a limestone country is a rich country0 is a popular axiom to which there are1 on the whole1 but few exceptions4 ,origin4--,actual observation of what is happening at the present time1 as well as the examination of the rock as anciently formed1 prove conclusively that with insignificant exceptions1 all limestones have been formed from the framework and shells1 and to some extent from the bones1 of marine and fresh-water organisms1 ranging in size from the extinct giants of the lizard relationship to those recognizable only by the microscope4 ,owing to the solubility of lime carbonate in carbonated water1 the organic forms have often 7in crystalline limestones7 been almost completely obliterated in some portions1 but in others are so preserved as to prove undeniably the similarity of origin of the whole1 and that they have been formed in relatively shallow water1 as they are to-day4 ,impure ,limestones as ,soil-formers4--,from what has been said regarding the composition of sea-water1 it will readily be inferred that a pure deposit of any one kind cannot easily be formed in it2 moreover1 the matter held in mechanical suspension everywhere near the coasts must very commonly be included within the calcareous deposits formed off-shore4 ,hence few limestones dissolve in acids without leaving a residue of sand1 clay and various other substances1 usually even some organic matter not fully decomposed2 sometimes less than half of the mass is really lime carbonate4 ,it is obvious that when the solvent action of carbonated water is exerted upon such impure limestones1 a loose residue of earthy matters will remain behind4 ,it is by this process that a considerable proportion of the richest soils in the world have been formed1 which have given rise to the popular maxim above quoted4 ,they are emphatically 8residual0 soils2 sometimes1 it is true1 somewhat removed1 by washing-away1 from their point of origin1 but in many cases forming a compact soil-layer on top of the unchanged rock1 into which there exists every shade of transition4 ,striking examples of such residual soils in place are seen in the black prairies of the southwestern ,united ,states2 they are mostly rather 8stiff0 7clayey71 and hence has arisen a local popular error1 to the effect that clay or 8heavy0 soils are always calcareous4 ,on the other hand1 the blue-grass region of ,kentucky1 and most of the lands of the arid regions are prominent examples of 8light0 calcareous soils4 ,caves1 ,sinkholes1 ,stalactites4--,perhaps the most striking exemplification of the solvent power of carbonated water is seen in the formation of limestone caves4 ,as a matter of fact1 the vast majority of all existing caves is found in limestone formations2 and such formations1 as will be more fully discussed hereafter1 nearly always bear a luxuriant vegetation4 ,the water filtering through the vegetable mold1 in which carbonic acid is constantly being formed1 becomes charged with it1 and on reaching the underlying rock1 dissolves to a corresponding extent the lime carbonate of which this rock wholly or chiefly consists4 ,when penetrating crevices it soon enlarges these1 to an extent proportioned to the length of time and the strength of the solvent2 and thus gradually subterranean passages or caves are formed1 which at first are almost always the bed of a stream1 the mechanical action of which accelerates the process of enlargement1 until after some time the water is perhaps drained off through some crevice to a lower level1 where the same process is repeated4 ,sometimes the ceiling gives way1 forming the funnel-shaped 8sinkholes0 or 8lime-sinks0 so familiar in some of the ,mississippi ,valley ,states4 ,sometimes the lime solution on reaching the ceiling of the cave1 instead of dropping down1 evaporates there and eventually forms icicle-like 8stalactites0 out of the dissolved substance2 while when dropping on the floor and thus growing upwards1 the corresponding formation is called 8stalagmite40 ,these caves1 subterranean rivers1 sinkholes1 natural bridges and tunnels1 etc41 mostly owe their origin to this solvent action of carbonated water on limestone formations4#ae #ae ,t4 ,m4 ,reade 7in his treatise on ,chemical ,denudation in ,relation to ,geological ,time7 calculates that #adc4e tons of lime carbonate are annually removed by solution from each square mile of land in ,england and ,wales1 and that the average amount thus removed annually from each square mile of the earth's surface is about fifty tons4 ,the same occurs on a small scale1 when calcareous land is underdrained2 the lime carbonate dissolved from the soil is partially deposited in the drain pipes1 which it frequently obstructs4 ,similarly1 an impure1 porous deposit of calcareous tufa is frequently formed on the surface1 at the foot or in rills of calcareous hills4 ,when 8hard0 water1 being usually such as contains lime carbonate dissolved in carbonic acid1 is boiled1 or long exposed to the air1 carbonic gas escapes and the lime salt is deposited partly on the walls of the kettle1 partly forming a pellicle on the surface of the water4 ,dolomite1 or bitter spar1 greatly resembles calcite in its aspect and properties1 although containing nearly half its weight 7#dg4f7 of magnesic1 together with calcic carbonate4 ,it is1 however1 nearly always whitish-opaque2 its crystalline and cleavage surfaces are usually somewhat curved2 and its effervescence with acids is much less lively than in the case of calcite4 ,like the latter it often forms pure granular rock deposits1 frequently used instead of marble and limestone1 and under that designation4 ,the dolomite rocks1 however1 are much more subject to weathering than the non-magnesian limestones1 and it is a curious fact that in contradistinction to the limestone regions proper1 those having strongly magnesian limestones or dolomites as their country rock are frequently remarkably sterile4 ,in some portions of ,europe dolomite areas are sandy deserts1 whose sand consists of weathered dolomite1 so pure as to offer no adequate supply of mineral food to plants4 ,in the ,united ,states1 magnesian limestones underlie the 8barrens0 of several ,states and thus seem to justify their ,european reputation of being poor soil-formers4 ,the exact cause of this difference is not fully understood1 for at first sight it is not clear why the presence of the magnesian carbonate should interfere with the well-known beneficial effects of the lime compound4 ,o4 ,loew and ,may#af and others have1 however1 shown that a certain excess of lime over magnesia in the soil is necessary to prevent the injurious effects exerted by magnesic compounds on plant nutrition1 in the absence of an adequate supply of lime4 ,this point will be discussed more in detail farther on4 #af ,bull4 ,no4 #a1 ,u4 ,s4 ,dept4 ,agr4 ,veg4 ,path4 and ,physiol4 ,investig4 ,selenite or ,gypsum1 sulfate of lime with about #ad per cent of water1 though not as abundant in nature as the carbonate or limestone1 is a very widely disseminated mineral and often occurs in large masses over considerable areas4 ,these are undoubtedly in most cases the result of evaporation of sea water 7see p4 #bf71 more rarely of the transformation of limestone4 ,in mass it frequently resembles the latter1 but is readily distinguished by its softness2 it does not grit between the teeth1 is readily cut with a knife and does not effervesce with acids4 ,very commonly it occurs in crystals1 which are easily split into thin plates4 ,the crystals are very frequently found imbedded in gray or bluish1 tough clays1 in rosettes1 or flat sheets which mostly show characteristic incurrent angles 7caused by twinning71 and are hence known as 8swallowtail0 crystals4 ,such sheets of selenite are popularly called 8isinglass10 which name however is equally applied to the mineral mica 7see p4 #ce74 ,gypsum is only exceptionally an abundant ingredient of soils2 yet such soils prevail quite extensively on the upper ,rio ,grande1 in ,new ,mexico and adjacent portions of ,chihuahua1 ,coahuila1 and on the ,staked ,plains of ,texas4 ,here whole ranges of hills are sometimes composed of gypseous sand1 bear a scanty1 peculiar vegetation1 and are ill adapted to agricultural use4 ,it may be said in general that few naturally gypseous soils are very productive4 ,this is largely because of the very heavy clays which commonly accompany it1 as the compound itself is not only not hostile to plant life but is in extended use as a valuable fertilizer 78land plaster07 for special purposes4 ,from causes not fully understood as yet1 it particularly promotes the growth of leguminous plants1 notably the clovers2 and as stated in chapter #i1 it also specially favors nitrification in soils4 ,in the arid region it renders important service in the neutralization of 8black alkali0 or carbonate of soda in alkali soils4 ,being soluble in #djj parts of water1 it easily penetrates downward in most soils1 and in doing so effects changes in the zeolitic portions1 setting free potash from silicates and thus indirectly supplying plants with this essential ingredient in a soluble form4 ,about #bjj pounds per acre is an ordinary dose4 ,for agricultural use the rock gypsum is ground in mills so as to be easily distributed1 and dissolved by the soil water4 ,frequently1 however1 it occurs in the soft granular form 7gypseous marl7 requiring only light crushing2 thus in the hills bordering the ,great ,valley of ,california1 and in parts of ,new ,mexico and ,texas4 ,iron ,minerals4--,in connection with calcite and dolomite1 the several minerals constituting the common iron ores require mention4 ,one of these is3 ,iron ,spar or siderite2 carbonate of iron1 corresponds in composition to calcite and dolomite and crystallizes in the same form4 ,it sometimes occurs in large masses and is an important iron ore1 brownish-white in color1 and when compact resists the attack of atmospheric oxygen remarkably well4 ,like the carbonates of lime and magnesia1 it is soluble in carbonated water1 and its deposits are undoubtedly formed from such solutions4 ,the latter are copiously formed wherever fermenting or decaying organic matter is in contact with iron-bearing materials1 such as rust-colored sands or clays2 and if the solution so formed can percolate without coming in contact with air1 iron spar is formed4 ,but whenever the solution comes in contact with air1 it absorbs oxygen and the ferrous carbonate is converted into ferric hydrate or rust1 mineralogically known as3 ,limonite or brown iron ore4 ,this ore is frequently found deposited on the upper surface of clay layers traversing sandy strata1 the clay having arrested the carbonate solution and thus given time to the air to effect the change4 ,sometimes such deposits form great masses in rock-caves1 fissure-veins1 or crevices2 and like siderite1 it is an important iron ore1 though frequently quite impure1 as in the case of bog ore1 which is formed in ill-drained subsoils4 ,it is also sometimes found as the residue from the weathering of rocks rich in hornblende or pyroxene1 and in this1 as well as in other cases1 is pulverulent1 constituting yellow ochre4 ,it makes a rust-colored streak on biscuit porcelain or unglazed queensware4 ,it is the coloring material of all yellow or 8red0 soils and clays1 as well as of brown sandstones1 which are cemented by it4 ,as is well known1 such clays and sandstones become dark red by heating or 8burning10 as in the case of common brick clays2 the brown or yellow ferric hydrate losing its water and becoming red ferric oxid4 ,the latter sometimes occurs in nature in the impure1 pulverulent condition1 constituting 8red ochre02 but more commonly and abundantly it is found in the form of ,hematite or red iron ore1 which is sometimes formed in nature by limonite losing its water1 but more commonly in different ways4 ,it is but rarely found in soils and is of no special interest in that connection4 ,a fourth form of iron ore1 quite common in the soils of some regions1 is ,magnetite or magnetic iron ore1 also known as lodestone4 ,this mineral1 the oxygen-compound of iron corresponding to 8blacksmith's scale10 also occurs in large masses and is an important and usually a very pure iron ore4 ,it occurs very commonly disseminated through certain rocks1 and in their weathering it remains unattacked and thus passes unchanged into the soils and sands1 constituting the 8black sand0 so well known to gold miners and almost universally present in the alluvial soils of the ,pacific coast4 ,these black grains are of course attracted by the magnet and can thus be easily recognized and extracted4 ,in soils they are simply inert1 like quartz sand4 ,but while the ore is of little interest to the farmer1 it is quite otherwise with the compound of this oxid with water1 the ferroso-ferric hydrate2 intermediate in composition between the white ferrous and the brown ferric hydrates4 ,as mentioned above1 the black silicate minerals1 such as hornblende and pyroxene1 are bottle-green when seen in thin sections4 ,nearly the same color1 with modifications running toward blue and bright green1 is often seen in natural clays and rocks1 and is almost always caused by the ferroso-ferric hydrate4 ,such materials always become red or reddish when heated by the formation of red ferric oxid2 while when exposed to damp air1 they assume the rust color of ferric hydrate4 ,reduction of ferric hydrate in ill-drained soils4--,when such oxidized1 rust-colored clays or soils are exposed to the action of fermenting organic matter1 the first effect observed is the change of color from rusty to bluish or greenish1 by the reduction of the ferric to ferroso-ferric hydrate4 ,afterward1 if the action is continued1 the solution of ferrous carbonate 7see above7 may be formed1 and the greenish or bluish color may disappear4 ,the importance of this reaction to farming practice lies in the fact that the blue or green tint1 wherever it occurs1 indicates a lack of aeration1 usually by the stagnation of water1 in consequence of imperfect drainage4 ,such a condition1 always injurious to plants1 becomes doubly so when it is associated with the formation of a metallic solution1 such as ferrous carbonate1 and promptly results in the languishing or death of plants in consequence of the poisoning of their roots4 ,in the presence of sulfates such as gypsum1 the formation of iron pyrite 7ferric bisulfid7 and sulfuretted hydrogen1 is likely to take place4 ,moreover1 under the same conditions the phosphoric acid of the soil may be concentrated into ferrous or ferric phosphate1 which pass into deposits of bog ore in the subsoil4 ,,chapter ,,iv4 ,,the ,,various ,,rocks ,,as ,,soil-,,formers4 ,rock-weathering in arid and humid ,climates4--,from what has been said in the preceding chapters of the physical and chemical agencies concerned in rock-weathering1 it is obvious that climatic differences may materially influence the character of the soils formed from one and the same kind of rock4 ,since kaolinization is also a process of hydration1 the presence of water must greatly influence its intensity1 and especially the subsequent formation of colloidal clay2 so that rocks forming clay soils in the region of summer rains may in the arid regions form merely pulverulent soil materials4 ,many striking examples of these differences may be observed1 e4 g41 in comparing the outcome of the weathering of granitic rocks in the southern ,alleghenies with that of the same rocks in the ,rocky ,mountains and westward1 especially in ,california and ,arizona4 ,the sharpness of the ridges of the ,sierra ,madre1 and the roughness of the hard granitic surfaces1 contrasts sharply with the rounded ranges formed by the 8rotten0 granites of the ,atlantic slope1 where sound1 unaltered rock can sometimes not be found at a less depth than forty feet2 while at the foot of the ,sierra ,madre ridges1 thick beds of sharp1 fresh granitic sand1 too open and pervious to serve as soils1 cover the upper slopes and the 8washes0 of the streams1 causing the latter to sink out of sight4 ,a general discussion of the kinds of soils formed from the various rocks must1 therefore1 take these differences into due consideration4 ,,general ,,classification ,,of ,,rocks4 ,rocks may be broadly classified into three categories1 viz3 #a4 ,sedimentary rocks1 formed by deposition in water and hence more or less distinctly stratified4 #b4 ,metamorphic rocks1 formed from rocks originally sedimentary1 by subterranean heat in presence of water4 ,usually crystalline1 that is1 composed of more or less distinct 7large or minute7 crystals of one or several of the minerals mentioned above4 #c4 ,eruptive rocks1 ejected in the molten state from volcanoes or fissures2 crystalline or not1 according to slow or rapid cooling4 ,sedimentary ,rocks4--,sedimentary rocks are forming to-day by deposition from either sea or fresh water1 precisely as they were in the most remote geological times2 the oldest clearly sedimentary rocks being sometimes undistinguishable in their nature and composition from the very latest immediately preceding our present time4 ,they may for the purposes of the present work be simply classified as follows3 #a4 ,limestones1 formed in comparatively shallow seas1 or fresh water basins1 from the calcareous shells or skeletons of various organisms4 #b4 ,sandstones1 and conglomerates 7sometimes called pudding-stones7 formed from the debris of pre-existing rocks disintegrated by the agencies described above1 7chap4 #a-b71 re-cemented by means of solutions of one or several substances1 such as silex1 carbonate of lime1 ferric hydrate and others4 ,loose sands and gravels are the initial stages of such rock formation as well as the results of their disintegration4 #c4 ,clays1 ,claystones and ,clay shales1 consisting of clay substance with more or less sand1 and soft or hard according to the nature of the waters or solutions that may have acted upon them1 with or without the aid of heat4 ,these rocks can only be formed in comparatively quiet or 8back0 waters1 since clay would not ordinarily be deposited in moving water4 ,metamorphic ,rocks4--,the effects of subterranean heat or metamorphism upon the sedimentary rocks may be roughly stated as follows3 ,limestones are transformed into marbles of various degrees of purity1 according to the nature of the original rocks4 ,sandstones when cemented by silex are transformed into quartzite1 of greater or less purity according to the nature of the 8sand0 entering into its composition4 ,when cemented by materials other than quartz1 these also will be segregated in the form of various minerals in the body of the rock4 ,the clay rocks form the most varied products under the influence of 7aqueo-igneous7 metamorphism2 granites1 gneiss1 syenite and hornblendic schist are among the most common4 ,the great variations in the composition of clayey materials account for the correspondingly great variations in the nature of the resultant metamorphic rocks4 ,igneous or ,eruptive ,rocks4--,these are usually divided into two groups2 the one characterized by a large proportion of free quartz 7silicic acid71 and hence designated as acidic1 and usually of a light tint2 the other the basic1 containing little or no free quartz1 and commonly of a dark tint caused by the presence of a large amount of iron 7contained in pyroxene1 more rarely in hornblende74 ,of the latter class are the dark 8basaltic0 rocks constituting the mass of the enormous eruptive sheet of the ,pacific ,northwest1 covering the greater part of ,washington1 ,oregon and northeastern ,california4 ,the lavas of the ,hawaiian islands are of the same class and even more basic2 while the eruptives of ,nevada1 middle and southern ,california1 and eastward to the ,rocky ,mountains1 are mostly of the light-colored1 acidic type4 ,the same is largely true of the rocks of the ,andes of ,central and ,south ,america1 the gray 8,andesites10 also represented in the ,caucasus4 ,as one and the same eruptive material may1 according to the greater or less rapidity of cooling1 appear as a glassy mass 7obsidian1 pumice1 volcanic ash1 tuff1 etc417 or as a crystalline rock resembling coarse granite in structure1 it is not easy to identify them in all their various forms4 ,this can frequently be done only by ascertaining their component minerals by the microscope1 or by chemical analysis4 ,the same is sometimes true of metamorphic rocks2 and as in the latter1 the several feldspars and quartz1 with pyroxene instead of hornblende1 constitute the predominant soil-forming minerals4 ,more rarely1 garnet1 chrysolite1 leucite and other silicates require consideration4 ,generalities regarding the ,soils derived from various ,rocks4 ,it is hardly necessary to insist that as in the case of the rocks composed of single minerals1 already referred to above1 the predominant mineral or minerals of compound rocks determine the facility of weathering1 as well as the quality of the soil resulting therefrom4 ,since rocks are named essentially in accordance with the kinds of minerals that constitute their regular mass1 the proportion in which the several constituents stand to each other may vary greatly4 ,thus a granite may consist1 over considerable areas1 mainly of a mixture of potash feldspar and quartz2 in others1 mainly of quartz and mica with little feldspar4 ,very frequently1 hornblende replaces mica partially or wholly4 ,the latter will weather much more slowly than feldspar or hornblende1 and will produce an inferior soil when decomposed4 ,allowing for such variations1 a fairly approximate general estimate of the quality and peculiarities of soils from crystalline rocks may nevertheless be made4 ,to some extent such estimates must make allowance not only for the chief ingredients1 but also for those which are called 8accessory0 or characteristic1 and which while not present in large amount1 may nevertheless exert a considerable influence upon the quality of the soil4 ,soils from granitic and crystalline rocks4--,in the case of the 7potash-feldspar7 granite soils it is generally admissible to expect that they will be fairly supplied with phosphoric acid1 because in the great majority of cases1 minute crystals of apatite 7phosphate of lime7 are more or less abundantly scattered through it4 ,from the potash feldspar present1 granite soils may always be relied on for a good supply of potash for plant use2 on the other hand1 unless hornblende be present1 they are pretty certain to be deficient in lime1 since neither lime1 feldspar nor calcite are probable accessory ingredients of this rock4 ,granite is exceedingly apt to weather by mechanical disintegration far in advance of its chemical decomposition4 ,it is therefore common to find in sedentary soils overlying granite1 a gradual increase of grains of its component crystalline minerals as we descend in the subsoil2 until finally the latter grades off into rock almost unchanged save in lacking coherence4 ,this is seen strikingly in the southern ,appalachians1 as well as in the ,sierra ,nevada and ,sierra ,madre of ,california2 at ,cintra in ,portugal1 at ,heidelberg in ,germany1 and elsewhere4 ,but of the rocks that resemble granite and are popularly so called1 a good many are not 8true to name0 and therefore form soils differing materially from the type just mentioned4 ,thus the so-called granite areas of the ,sierra ,nevada of ,california are largely occupied by a rock containing1 besides quartz1 chiefly soda-lime feldspar and some hornblende1 and scarcely any mica4 ,it is more properly a diorite 7grano-diorite72 the soils formed from it are rather poor in potash1 not strongly calcareous1 and quite poor in phosphoric acid4 ,on account of the small proportion of hornblende 7unusual in diorites71 these soils are light-colored 7not 8red071 and bear a growth of small pine instead of the usual oak growth of the lower ,sierra slopes4 ,what is said of granite soils is also generally true of those formed from ,gneiss1 which is composed of the same minerals as granite1 but has a slaty cleavage and on that account when upturned on edge1 weathers rather more rapidly than most granites4 ,owing to the frequent occurrence of lenticular masses of quartz in gneiss1 its soils are more commonly of a siliceous nature than are those of the true granite regions1 and not as 8strong0 as the latter4 ,this is the more true since gneiss often passes gradually into mica schist1 which1 being a mixture of quartz and mica only1 not only weathers very slowly but also supplies but little of any importance to plants1 to the soils formed from it4 ,such soils would mostly be absolutely barren but for the frequent occurrence in the rock1 of accessory minerals that yield some substance to the soil4 ,yet it remains true that inasmuch as gneiss and mica-schists are among the rocks in which mineral veins most commonly occur1 the proverbial barrenness of mining districts is very frequently traceable to these rocks4 ,the same may be said of some of the related rocks1 such as gabbro1 minette and others4 ,normal diorite consists of hornblende and soda-feldspar1 with more or less quartz4 ,the soils derived from certain diorites of the ,sierra ,nevada of ,california have just been referred to4 ,but these granite-like diorites are on the whole exceptional2 it should be added that the 7diabasic7 8greenstones0 of the ,eastern ,united ,states and of the ,old ,world1 which are usually much finer-grained1 do not form the mass of fine1 angular debris constituting the subsoil in the ,sierra ,nevada1 but weather into rounded masses and fine-grained soils possessing1 on the whole1 a fair fertility1 though liable to contain an excessive proportion of silex in various forms4 ,of the eruptive rocks as a class it is often said that they form very productive soils2 yet1 as these rocks differ widely from each other in composition1 this statement must be taken with a great deal of allowance4 ,very many of them decompose with extreme slowness on account of their glassy nature2 this is particularly true of obsidian1 pumice stone1 and the 8volcanic ash0 derived from its pulverization1 and which is found unchanged1 in sharp scales1 among the decayed minerals of other rocks in complex soils4 ,other volcanic ash1 however1 being formed by the pulverization of crystalline or of basic lavas1 weathers rather readily1 as already stated2 so that certain plants take possession in the course of a few years4 ,the general classification into basic and acidic rocks1 given above1 is of importance in connection with soil formation from eruptive masses2 for the basic rocks are much more easily attacked by the atmospheric agencies than the acidic class4 ,a broad distinction must1 however1 be made between the basic rocks of the basaltic class1 which contain black pyroxene as a prominent ingredient1 and those which1 like many trachytes1 are rich in feldspathic minerals4 ,the latter are naturally rich in alkalies 7potash and soda7 which they impart to the corresponding light-colored soils2 while the black basaltic rocks and lavas weather into 8red0 soils1 sometimes containing extraordinary amounts of iron 7ferric hydrate7 and 7from the lime-feldspars they contain7 a fair supply of lime1 but oftentimes very little potash4 ,experience seems to prove that the red basalt soils are mostly rather rich in phosphoric acid2 this is especially true of the country covered by the great eruptive sheet of the ,pacific ,northwest1 in the rocks of which the microscope readily detects the presence of numerous needles of apatite 7lime phosphate74 ,the same is true of the highly iron-bearing soils from the black basaltic lavas of the ,hawaiian islands1 even though they have been leached of all but traces of lime and potash4 ,all these soils are physically 8light0 and easily workable1 since the rocks in question contain but little alumina from which to form clay2 they are sometimes extremely rich in iron1 even to the extent of being capable of serving as iron ores4 ,the soils derived from trachytes and trachytic lavas are generally light-colored and light in texture2 the latter from the presence of a large proportion of volcanic glass1 together with undecomposed crystalline minerals4 ,these are usually rich in potash1 but poor in lime and phosphates4 ,the high quality of the wines of the lower ,rhine has been ascribed to these soils1 which however vary greatly within the areal limits of the production of the high-grade wines1 not only from gray trachytes to dark colored1 highly augitic basalt1 but also to acidic quartz porphyries or rhyolites1 and clay-slates4 ,the rhyolites on the whole yield the poorest soils among the eruptive rocks2 they are slow to weather at best1 and the soils produced are poor and unsubstantial1 largely from the predominance of quartz and undecomposable1 glassy material2 of which the phonolites are the extreme type1 resisting the influence of the atmospheric agencies just as would so much artificial glass4 ,soils consisting largely of volcanic glass may be found covering considerable areas in the ,sierra ,nevada of ,california4 ,such 8volcanic ash0 soils are usually very unthrifty1 and bear a growth of small pines4 ,soils from sedimentary rocks4--,limestones1 when pure and hard1 are very slow to disintegrate1 and are also very slowly attacked by carbonated water 7see chap4 #c1 page #da74 ,soft impure and vesicular limestones are1 however1 very rapidly attacked1 especially when underlying a surface clothed with the luxuriant vegetation that usually flourishes on soils rich in lime4 ,the popular adage that 8a limestone country is a rich country10 is of almost universal application and stamps lime1 from the purely practical standpoint1 as one of the most important soil ingredients4 ,residual ,limestone ,soils4--,striking examples of the formation of large1 fertile soil areas by the leaching out of limestones are found in the ,states of ,alabama1 ,mississippi1 ,louisiana and ,texas1 where the fertile black prairies have been largely thus formed4 ,the 8blue-grass0 country of ,central ,kentucky is another case in point4 ,the following table shows a representative example of the relative composition of the 7cretaceous7 8,rotten ,limestone0 of ,mississippi1 and the 8residual0 soil-stratum derived from it4 ,the average thickness of the layer of residual clay above the limestone is about eight feet1 but ranges from seven to ten2 the upper layers of the limestone are somewhat softened1 but the rock is always fresh at twelve feet1 from which depth the sample analyzed was taken1 in a cistern adjoining the field from which the soil and subsoil were procured4 ,the black soil varies in depth from #h to #ae inches2 then there is a change to a brownish subsoil1 reaching down to about two feet1 and in drying cleaving into prismatic fragments4 ,the black soil has here in the highest degree the peculiarity of crumbling in drying from its water-soaked condition1 so that it may be plowed when wet without injury1 although in the roads it works up into the toughest kind of mud4 ,the prairie is sparsely timbered with compact1 fair-sized black-jack oak1 accompanied originally by red cedar4 ,the limestone derives its popular name of 8rotten0 from its being usually soft enough to be cut with a knife or hatchet1 and is therefore somewhat used for building1 and for burning lime4 ,,composition ,,of ,,limestone1 ,,and ,,residual ,,soil ,,and ,,subsoil1 ,,from ,,black ,,prairie1 ,,monroe ,,co41 ,,mississippi4 8,,rotten ,,subsoil ,,soil ,,limestone40 7,,yellow747,,black74 ---------------------------------------- --------------------- ,,fine ,,earth4 ,depth #ab ft4 #b-c ft4 #ae ins4 ,chemical analysis of fine earth4 ---------------------------------------- --------------------- ,insoluble matter #aj4ij #ga4ed #gh4bi ,soluble silica ,potash 7,k,o7 4#be 4#ed 4#cc ,soda 7,na,o7 4#cb 4#bc 4#jh ,lime 7,ca,o7 #de4gi #a4jh #a4cg ,magnesia 7,mg,o7 4#hh 4#gg 4#cf ,br4 ,ox41 of ,manganese 7,mn,o7 4#je 4#ad ,peroxide of ,iron 7,fe,o7 #a4db #e4db ,alumina 7,al,o7 #a4if #ac4ae #ad4bb ,phosphoric ,acid 7,p,o7 4#je 4#aj ,sulfuric ,acid 7,,so7 4#jd 4#jc ,carbonic ,acid 7,,co7 #ce4gc ,water and ,organic matter #b4hd #f4ii #e4ge ------ ----- ------ ,total #ajj4ji #ii4hf #ajj4fg ,humus #a4ic 8 ,ash #d4ch ,hygroscopic moisture #aj4ce #ab4hb absorbed at ,c #ai #ai ---------------------------------------- --------------------- ,it appears from the above table that in the change from the original limestone to the soil mass as found at three feet depth1 #ha4e of the lime carbonate has been eliminated by leaching1 leaving behind somewhat less than one fifth of the original mass4 ,taking the average depth of the soil mass at #h feet1 this thickness of material has required about #de feet of the rotten limestone4 ,considering that notwithstanding the tenacity of the clay soil1 some of it must in the course of time have been washed away1 we may safely assume that the original rock surface was from #ej to #fj feet higher than at present4 ,sandstone ,soils4--,the indefiniteness of the nature of 8sandstones0 as such renders generalizations in regard to the soils formed from them rather difficult1 save as to their physical qualities1 which in the nature of the case are always 8light40 ,in the ,old ,world and in the humid region generally1 sandstone and sandy soils are usually spoken of as being poor1 because there the sand almost always consists of quartz grains only1 and hence the fine portions alone can be looked to for plant nutrition4 ,consequently1 the more sand is seen in a soil1 the poorer it is usually presumed to be4 ,but this presumption would be wholly erroneous in the arid regions4 7,see chapt4 #f1 p4 #hf74 ,clearly1 the nature of the soils produced by the weathering of sandstones depends upon two points3 first1 the nature of the cement binding the sand grains1 and second the character of the latter themselves4 ,varieties of ,sandstones4--,as has been stated above1 the cements may be roughly classified into five kinds1 and their intermixtures1 to wit3 quartzose or siliceous1 calcareous1 ferruginous1 aluminous or clayey1 and zeolitic4 ,as regards the first1 it is obvious that siliceous sandstones will disintegrate with great difficulty1 since neither the cement nor the grains are susceptible of material change by weathering4 ,such sandstones frequently pass insensibly into quartz rock1 and the light1 unsubstantial soils they produce are of the poorest1 containing often mere traces of the plant-food ingredients4 ,this of course1 is true1 not only of the soils formed by the actual weathering of sandstones1 but equally of those consisting of quartz-sand deposited by water or drifted by winds4 ,of this character are the pine-forest soils of the coast region of the ,gulf of ,mexico1 particularly the 8,sand hammocks0 of the immediate ,gulf border1 from ,mississippi ,sound to ,charlotte ,harbor1 ,florida2 the sandy lands of the ,grand ,traverse region of ,michigan1 and many other minor areas in the ,united ,states1 usually characterized by a pine growth1 often more or less stunted1 according to the nature of the sand grains4 ,calcareous sandstones usually form a very much better class of soils1 partly for the intrinsic reason given above as regards limestones as soil-formers4 ,the calcareous cement is very rarely pure calcite2 in most cases it is very impure1 as1 most commonly1 is also the 8sand0 itself4 ,this is explained from the fact that such rocks 7mostly soft and often quite unconsolidated7 are1 like limestones themselves1 the result of deposition in shallow seas or lakes1 receiving deposits from the land drainage1 and enriched by the animal and vegetable life of such waters4 ,not uncommonly they contain1 disseminated through them1 grains of the mineral glauconite 7a hydrous silicate of iron and potash71 which readily supplies available potash2 while the remnants of animals and plants furnish more or less of available phosphates4 ,thus the general presumption regarding calcareous sandstones is that the derived soils are of good quality1 frequently of the very best4 ,the same1 however1 does not appear to be true of sandstones cemented by dolomite2 the soils derived from magnesian sandstones are in many cases noted for their unproductiveness4 7,see chapt4 #c1 p4 #db74 ,ferruginous ,sandstones manifestly derive no important soil ingredients from their cement when the latter is measurably pure ferric hydrate2 and when in addition the sand itself is purely siliceous1 the soils resulting from the disintegration of the rocks are very poor4 ,such are1 e4g41 the soils derived from the ferruginous sandstones of the ,lafayette formation in a part of northern ,mississippi and adjacent portions of ,tennessee and ,alabama1 characterized by small scrubby oak or dwarfed pine4 ,on the whole1 however1 such purely ferruginous quartz sandstones are exceptional1 and should not detract from the favorable inferences usually to be drawn from the iron-rust tint of soils 7see chapter #ae74 ,sandstones with purely zeolitic cement are on the whole not of frequent occurrence1 the zeolites forming1 more commonly1 the hard portion of a clay-sandstone cement1 which disintegrates by their weathering-out4 ,in regions where the tufaceous rocks of eruptives prevail1 we not uncommonly find the 8volcanic ash0 solidly cemented by a zeolitic mass1 which is then usually apparent in cavities or crevices in the form of crusts or crystals4 ,such tuffs are commonly rich in alkalies and lime1 but mostly poor in phosphates1 and in disintegration form soils of a corresponding nature4 ,they are largely represented in the valleys off ,puget ,sound1 as well as in portions of central ,montana1 and northward4 ,clay-,sandstones 7argillaceous sandstones7 when soft1 as is mostly the case1 form as a rule desirable loam soils1 of a generalized composition1 difficult to predict4 ,it is here that the composition of the sand grains themselves most frequently comes into play in modifying the soil quality4 ,from clay-sandstones to claystones of various degrees of sandiness there is1 of course1 every grade of transition1 the soils ranging correspondingly in the scale of lightness or clayeyness4 ,as a general rule1 the potash contents of such soils are sensibly proportioned to the clayey ingredient1 at least in the humid regions4 ,claystones 7i4 e41 clays hardened by some one or more of the cements mentioned in connection with sandstones71 will in the nature of the case1 when disintegrated from the condition in which they lie in the geological formations1 make correspondingly clayey1 heavy soils1 which as experience shows are usually rich in the ingredients of plant food1 but frequently too heavy and intractable in tillage to be readily utilized4 ,there are1 of course1 exceptions2 such as soils formed from pipe-clays1 in which little if any mineral plant-food remains1 and which are best used for other purposes than agriculture1 unless under special conditions it may be worth while to reclaim them by fertilization4 ,natural ,clays4--,clays occur in nature in a great variety of modifications that have received designations known in common life4 ,such are porcelain clay1 pipe-clay1 fire-clay1 potters' clay1 brick-clay1 and many others of more or less local use only4 ,as these materials practically concern the farmer in very many cases1 they may properly find a brief discussion here4 ,the variety-names enumerated above in the order of the actual contents of the materials in true clay substance 78colloidal clay071 are partly based upon that fact1 partly upon the degree of plasticity attained by that substance1 and essentially upon the nature and amount of foreign admixtures associated with it4 ,thus1 porcelain clay is chalky kaolinite1 sometimes associated with enough of pure white plastic clay to render it workable in the potter's lathe1 but more commonly requiring to be molded in porous molds2 it is very refractory to heat4 ,pipe-clay is also white1 but more plastic and usually less refactory4 ,fire-clay is a refractory pipe-clay commingled with some coarse infusible material1 such as quartz sand 7or the same clay burnt and crushed71 in order to prevent excessive contraction and change of shape in drying and burning4 ,potters' clay is a much less pure1 and from that cause more fusible clay1 which when burnt forms at a moderate heat a semi-fused1 more or less hard mass1 such as crockery and pottery ware4 ,brick-clay is a still more impure clay1 or loam1 containing considerable sand and usually iron oxid1 and largely falls already within the limits of tillable soils or subsoils1 rendered fusible by the presence of relatively considerable amounts of iron1 magnesia and lime4 ,iron colors natural clays either red1 yellow1 green or blue2 the latter two colors turning to yellow or red on exposure to the air1 and to red on burning4 ,black color is usually due to carbon1 such clays often turning white on heating4 ,clays containing much lime are usually of a gray or whitish tint1 and like the soft crumbly limestones are often called marls1 and are used as such for land improvement4 ,but it should be understood that the colors of clays1 mostly derived from some iron compound1 have little to do with their uses in the arts1 except that no deeply colored clay 7black excepted7 is refractory in the fire4 8,colloidal0 ,clay4#ag ,in connection with soils1 clay may be defined1 in the most general terms1 as being the substance which imparts plasticity and adhesiveness to soils when wetted and kneaded1 and which1 when heated to redness1 loses this property completely and permanently1 becoming hard and coherent in proportion to the degree of heat to which it is exposed4 #ag ,this term was first employed by ,th4 ,schloesing1 in communications to the ,french ,academy of ,sciences1 and reported in the ,comptes ,rendus of that body2 first in #ahgj4 ,unaware of ,schloesing's work1 the writer began a full investigation of the subject of mechanical soil analysis in #ahga1 and published the results in #ahgc 7,am4 ,jour4 ,sci41 ,oct4 #ahgc74 ,up to that time the limited resources of the library of the ,university of ,mississippi had not given him an opportunity to see ,schloesing's publication4 ,the two independent investigations1 though conducted on somewhat different lines1 gave of course practically the same results1 and complement each other4 ,in common life1 however1 the name is applied to the whole of any naturally occurring earth which on wetting and kneading assumes a reasonable degree of plasticity and adhesiveness4 ,when the latter property becomes nearly or quite insensible1 the earth is designated as a 8loam10 more or less 8clayey0 according to the amount of the pure1 plastic and adhesive material associated with the mineral powders and sand that form the bulk of most soils4 ,chemically1 the pure clay substance#ah probably consists 7as has been stated above7 of silica and alumina in the proportion of nearly #df to #dj1 the rest 7#ad7 being water of hydration1 which is lost on burning the clayey material4 ,but while it is true that such is the composition of the plastic substance of clays1 plasticity and adhesiveness are by no means invariable properties of this compound4 ,in its purest state1 as kaolinite1 it is readily mistaken for chalk1 7and is sometimes used as such71 being powdery to the touch and entirely devoid of plasticity#ai when wetted and kneaded4 ,the microscope shows this chalky kaolinite to consist of minute1 mostly rounded1 originally six-sided1 thin plates1 which when pure resemble to the touch powdered talc 7soapstone7 or even black-lead1 rather than any clay known to common life4 ,but being exceedingly soft1 the kaolinite substance is easily ground or triturated into an extremely fine powder2 and ,johnson and ,blake#bj succeeded in producing sensible plasticity and adhesiveness by long-continued trituration of kaolinite with water in a mortar4 ,a similar process1 but continued much longer by the mechanical agencies concerned in soil-formation 7see chapt4 ,i71 is unquestionably the chief factor concerned in the formation of natural plastic clays2 but whether this is the only process by which the powdery kaolinite may be transformed into plastic clay1 is a question not definitely settled4 ,it is at least possible that repeated freezing and thawing1 as well as the action of hot water1 may take a part in the transformation1 beyond that by which they destroy the crumbly 7flocculated7 structure of soils and clays1 and render them plastic2 as is done in the maturing of clays by potters4 #ah ,there is still some discussion as to the chemical identity of colloidal clay with ,kaolinite2 but the objections are not convincing4 #ai ,it has of late been attempted to extend the meaning of this word to the behavior of all powders when wetted with water4 ,but the adhesive plasticity of clay stands almost alone1 in that 7aside from contraction7 it preserves in drying the form into which it may have been molded while wet1 even when struck1 whereas other powdery substances similarly treated at once collapse back into the original powder4 ,the exclusive use of clay in modeling offers the typical example of plasticity as generally understood4 ,the addition of any powdery substance1 however fine1 diminishes the plasticity of clay4 #bj ,american ,journal of ,science1 #b;d ,ser41 ,vol4 #dc1 p4 #ceg4 ,causes of ,plasticity4--,in any case the property of plasticity and adhesiveness is restricted to the particles so fine that they fail to settle1 in the course of #bd hours1 through a column of pure water eight inches 7#bjj m7 high1 while some are so extremely minute that they will not settle for many months1 and even for several years4#ba ,such turbid 8clay water0 may sometimes be found existing in nature1 in moist1 secluded places1 for weeks after the subsidence of the overflows of rivers whose water is exceptionally free from dissolved mineral matter4 #ba ,williams 7,forsch4 ,agr4 ,phys4 ,vol4 #ah1 p4 #bbe ff47 claims that the diameter of the minutest clay particles is one-thousandth of a millimeter1 their form being that of scales showing continual 7,brownian7 motion in water4 ,he maintains that the plasticity of clay is due to this minute size1 and this view has gained wide acceptance in late works on the subject4 ,but this assumption cannot be maintained in the face of the fact that nothing like the adhesive plasticity of clay can be attained even by the finest powders of other substances1 least of all by those having the closest mineralogical resemblance to kaolinite1 such as graphite and talc4 ,above all1 the most persistent trituration with water utterly falls to restore plasticity to clay once baked so as to expel its water of hydration1 although the fineness of the particles is thereby not only not diminished1 but actually increased1 by contraction in heating4 ,no powders however fine can replace the functions of clay in soils1 viz4 the maintenance of floccules1 and tilth dependent thereupon2 and they distinctly impair the plasticity of clay4 ,the fine 8slickens0 of quartz mills merely render soils containing them more close and impervious1 and more difficult to flocculate4 ,even gelatinous masses like hydrated ferric and aluminic oxids fail to replace clay in its adhesive functions4 ,separation of ,colloidal ,clay4--,this property of the plastic clay substance1 of diffusing in pure water1 furnishes the means of separating from it the coarser1 sandy and silty portions of soils and natural clays1 and observing its characteristic properties1 so far as the almost unavoidable admixture of some other substances1 presently to be considered1 permits4 ,in natural soils the clay particles usually incrust the powdery ingredients1 cementing them together2 or themselves form complex aggregates 7floccules7 of large numbers of individual particles4 ,these may be loosened from their adhesion or cohesion either by prolonged1 gentle kneading of the wet clay1 or by more or less prolonged digestion 7soaking7 in hot water1 or more expeditiously1 by lively boiling with water4 ,the boiling should not1 however1 be prolonged beyond the time actually required for disintegration1 since 7as ,osborne#bb has shown7 long-protracted boiling tends to render the clay permanently less diffusible4 ,from the turbid clay-water the diffused clay may be obtained either by evaporating the water 7which as the bulk is very large1 is usually inconvenient71 or1 more conveniently1 by throwing it down from its suspension by the action of certain substances which possess the property of curdling 7coagulating7 the clay substance into flocculent masses that settle quickly4 ,of all known substances1 lime1 in the form of lime-water1 acts most energetically in producing this change2 but other solutions of lime1 as well as most salts and mineral acids1 produce the same effects when used in sufficient quantity4 ,common salt is among the most convenient1 because it can most readily be leached out of the clay precipitate thus thrown down4 ,this when white1 resembles boiled starch1 but being usually colored by iron might be easily mistaken for the mixed precipitate of ferric hydrate and alumina so commonly obtained by chemists in soil analysis4 ,when separated from the water and dried1 the jelly-like substance 78colloidal clay07 shrinks as extravagantly as would so much boiled starch1 into hard1 shiny crusts or flakes1 which when struck in mass are sometimes even resonant1 and bear more resemblance to glue than to the clay of everyday life4 ,like glue1 too1 but much more quickly and tenaciously1 the dried colloidal clay adheres to the tongue1 so as to render the separation painful2 when wetted it quickly bulges with great energy1 and in a short time resumes its former jelly-like condition4 ,when moistened with less water it assumes a highly plastic and adhesive condition1 so that it is difficult to handle and almost as sure to soil the operator's hands as so much pitch4 #bb ,rep4 ,conn4 ,agr4 ,expt4 ,stn41 #ahhf1 #ahhg4 ,effects of ,alkali ,carbonates upon ,clay4--,the carbonate of potash and soda1 when in very dilute solution 74#ja to 4#je7 exert upon diffused clay an effect the reverse of the acids and neutral salts4 ,they destroy the flocculent aggregates formed by precipitation with these1 or naturally existing in the soil1 and tend to puddle the clay so as to render it impervious to water4 ,it is thus that in the alkali lands of the arid regions we often find the soil or subsoil consolidated into a very refractory 8hardpan10 difficult to break even with a sledge hammer and impossible to reduce to tilth until the alkali carbonate is destroyed by means of a lime salt1 such as gypsum4 7,see chapt4 #bc74 ,ammonia water also helps to cause the diffusion of clay in water1 but its effect of course disappears upon drying4 ,it is probable that this property of sodic carbonate can be utilized in rendering earth dams firmer and more secure against the penetration of water4 ,,chapter ,v4 ,,the ,,minor ,,mineralingredients ,,of ,,soils2 ,,mineral ,,fertilizers2 ,,minerals ,,injurious ,,to ,,agriculture4 7,a47 ,,minerals ,,used ,,as ,,fertilizers4 ,of minerals important in soil-formation1 not usually present in large amounts in rocks1 but extensively used in fertilization1 the following require mention3 ,apatite2 phosphate of lime containing more or less of the chlorids and fluorids of the same metal2 the mineral from which the phosphoric acid of the soil is mostly derived4 ,in the crystallized condition when perfectly pure it is colorless2 but it is mostly of a greenish tint 7hence 8asparagus stone074 ,the pure crystalline mineral rarely occurs in large masses 7as in ,canada72 but small to minute crystals are found widely disseminated in many rocks 7granites1 8basalts0 of the ,pacific ,northwest71 thus passing into the soils formed from these rocks4 ,these crystals are readily recognized1 being regular six-sided prisms with a flat or obtusely pyramidal termination 7distinction from quartz71 and do not effervesce with acids 7distinction from calcite74 ,by far the largest deposits of this mineral occur in connection with carbonate of lime1 in the rock materials known as phosphorites4 ,lime phosphate being1 like the carbonate1 soluble in carbonated water1 the two naturally frequently pass into solution1 and are subsequently deposited together4 ,most limestones contain a small proportion of lime phosphate1 being1 as already stated1 formed from the shells and the framework of animal organisms usually containing also phosphates4 ,but the content of phosphates in limestones is not readily apparent to the eye1 and the richest deposits1 save such as contain animal bones1 have long passed unsuspected as to their being anything else but limestone4 ,systematic search has now revealed the presence of phosphate rock in numerous localities1 chiefly where limestone formations occur4 ,in the ,united ,states1 in ,south ,carolina1 ,florida1 ,alabama1 ,tennessee1 ,kentucky1 ,nevada2 in ,south ,america1 on ,curaoa island1 ,venezuela2 in the ,antilles on ,sombrero1 ,st4 ,martins and ,navassa islands4 ,in ,africa1 in ,algiers and ,tunisia2 in ,europe1 in ,spain 7,estremadura1 one of the first deposits known71 ,france1 ,belgium and the adjacent parts of ,germany2 in ,bohemia and ,galicia in ,austria2 and very extendedly in ,european ,russia4 ,many islands of ,oceanica supply phosphorites derived from the decomposition of bird guano by the coral limestone4 ,unfortunately the percentage of phosphate in a large proportion of these materials is not sufficiently high to make their conversion into water-soluble superphosphate economically possible at the present time2 since all the calcic carbonate present must also be converted into comparatively worthless sulphate 7gypsum7 by the use of sulfuric acid2 and as yet no practicable method for avoiding this difficulty has been found4 8,thomas ,slag40--,probably the nearest approach to such a method is indicated by the fact that a compound containing four instead of three molecules of lime to one of ,p,o1 such as is contained in the 8,thomas slag0 of the basic process of steel manufacture1 is nearly or in some cases 78sour0 soils7 quite as effective for the nutrition of plants as the water-soluble superphosphate4 ,this discovery has rendered available for agricultural use the phosphoric acid contained in the enormous deposits of limonite iron ore known as bog ore1 which contains a large proportion of ferric phosphate and from that cause has until lately been excluded from the manufacture of wrought iron and steel4 ,it is reasonable to hope that by some analogous process the low-grade phosphorites1 such as those of ,nevada and the plains of ,russia1 will also in the course of time become available for agricultural use4 ,extremely fine grinding and washing 7producing 8floats07 has been resorted to for the purpose of rendering the raw phosphorites effective in fertilization4 ,but while this is successful on some soils1 on others the 8floats0 remain almost inert2 so that this method has found only limited acceptance4 ,animal bones1 which consist of from #bd to #cj of animal substance and #gj to #gf of 8bone earth10 7or when fossil are free from the former71 are largely used for the manufacture of superphosphate4 ,the bone-earth consists in the main of tri-calcic phosphate with from one to two per cent of calcium fluorid 7much as in natural apatite71 a small amount of magnesic phosphate1 and about #d to #f of calcic carbonate4 ,bone meal can therefore supply to plants both phosphoric acid and nitrogen1 and the presence of the latter has been largely the cause of a material overestimate of its efficacy as a fertilizer in the past4 ,wagner's and ,maerker's experiments have shown that at least in sandy soils poor in humus1 it cannot be considered an adequate source of phosphoric acid for annual crops1 and that in these soils its immediate effects are almost wholly due to its nitrogen-content4 ,the slow availability of the phosphoric acid renders it unprofitable as a source of the latter1 outside of the heavier lands with abundance of humus2 in 8sour0 lands 7notably on meadows7 bone meal produces its best results4 ,in soils naturally calcareous1 or in such as have received heavy dressings of lime either as carbonate or in the caustic condition1 the manurial effects of bone meal are seriously diminished4 ,nagaoka 7,bull4 ,coll4 ,agr4 ,tokyo1 ,vol4 #f1 ,no4 #c7 shows that the crop of rice fertilized with bone meal was reduced to less than half when limed1 and that the phosphoric acid taken up by the crop was reduced to one-sixth4 ,in any case it is most important that bone meal should be as finely ground as possible1 as in the case of the phosphorites2 and this can best be done when it has first been freed from fats by boiling with water1 and then steamed under pressure4 ,it can then also be most readily converted into superphosphate4 ,the phosphate minerals and the fertilizers manufactured therefrom are of primary importance to agriculture4 ,the phosphoric-acid content of soils is mostly very small1 and only a fraction of it is usually in an immediately available form4 ,hence for permanent productiveness1 and especially for intensive farming or gardening1 a cheap supply of phosphate fertilizers is of first importance in all soils and climates4 ,other phosphate minerals occur frequently1 but as a rule only in small amounts1 in connection with the ores of most metals4 ,the only ones of these of interest to agriculture are ,vivianite and ,dufrenite1 the phosphates respectively of the protoxid and peroxid of iron4 ,the former occurs in mineral deposits as small blue crystals1 or more frequently as blue earthy masses or streaks1 in the substrata of rich alluvial ground 7,louisiana1 ,california74 ,dufrenite sometimes results directly from the oxidation of the protoxid mineral1 which then turns greenish and finally brown4 ,unfortunately these minerals1 rich as they are in phosphoric acid1 cannot readily be utilized as sources of phosphate fertilizers1 because of the difficulty of getting rid of the iron4 ,their occurrence usually suggests the presence of abundance of phosphoric acid in the soil4 ,but that which is actually combined with the iron oxids is practically unavailable to plants2 especially so in the case of the peroxid compound1 the formation of which is a common source of loss of phosphoric acid when soils rich in iron are submerged for any length of time2 a point which is discussed below 7chapt4 #ac74 ,among the iron phosphate minerals1 may also be mentioned 8bog ore10 which results from the reductive maceration of swamped ferruginous soils1 and accumulates in the subsoils and in the bottom of swamps or moors1 forming 8moorbedpan02 a dark brown1 rather soft mass1 which is sometimes used as an iron ore1 especially since the invention of the 8basic process0 of iron smelting1 one of the products of which is the phosphate or ,thomas slag4 7,see above74 ,nitrate of ,soda or ,chile saltpeter4--,this mineral being 7like all nitrates7 easily soluble in water1 can only occur in regions nearly or quite destitute of rainfall4 ,such is the case in the ,plateau of ,tarapac in ,northern ,chile1 where it occurs in large quantities2 it is likewise found1 but to much smaller extent1 in ,nevada1 southern ,california1 ,egypt and ,india4 ,by far its most extended occurrence is that in ,chile1 where1 together with common salt1 it fills cavities and crevices in a gravelly clay that forms the surface of a plateau from three to six thousand feet above the sea4 ,it is never pure1 but always mingled with a large proportion 7up to #ej and over7 of common salt2 also some ,glauber's salt 7sulfate of soda7 and some sodic perchlorate and iodid2 hence it forms an important commercial source of iodine4 ,the mixed mineral mass1 called 8,caliche10 when taken out of the ground is dissolved in water2 and the solution boiled down1 during which process the common salt is first deposited and is raked out of the pans2 the nitrate is afterward farther purified by crystallization4 ,as brought into commerce for agricultural purposes it constitutes a moist gray saline mass1 somewhat resembling common salt1 of which substance it usually contains a few per cent2 occasionally also a small amount of sodic perchlorate 7which acts injuriously on vegetation74 ,aside from its use as a fertilizer1 ,chile saltpeter serves for the manufacture of nitric acid2 and either directly1 or after previous transformation into potassic nitrate1 for that of gunpowder4 ,the ,chilean locality is the only one from which the commercial article is derived2 the deposits elsewhere are too limited in extent to compete commercially with the ,south ,american product4 ,caliche ranging as high as #hj of nitrate of soda has been sent to the writer from the ,colorado ,desert in ,southern ,california1 but the exact locality of occurrence has not been divulged4 ,extended areas of clay hills impregnated with nitrates exist in the ,death ,valley region of ,california1 but in the absence or extreme scarcity of water in that region1 it is doubtful whether these impregnations can be made practically available4 ,another locality is that near ,white ,plains1 ,nevada1 where ,caliche averaging about #ej purity is found in cavities and crevices of a reddish volcanic rock4 ,the rainfall in this region is so slight that the greater part of the dust or sand blown about by the wind consists of ,glauber's salt4 ,here also1 as in ,chile1 the niter deposits appear to be restricted to within a short distance from the surface1 and the total amount thus far observed appears to be insufficient to encourage large-scale exploitation4 ,origin of ,nitrate ,deposits4--,the probable origin of these niter deposits has given rise to a great deal of discussion1 and a wide difference of opinion exists as to the source from which the nitrogen may reasonably be supposed to have been derived4 ,according to the present state of our knowledge1 it must be presumed that its sources have been organic1 and that the niter has been produced by the activity of the same bacteria which now produce nitrates in our soils1 rendering the nitrogen of humus available to plants4 ,but it is by no means clear what that organic material could have been2 for at the present time the plateau of ,tarapac is almost wholly destitute of vegetation1 if not of animal life4 ,the latest and apparently most reasonable suggestion is that of ,kuntze1 who calls attention to the fact that the vicuas and llamas which are at home in this portion of the ,andes1 and are known to have roamed over that region in countless herds1 have the curious habit of always depositing their manure in one and the same place whenever at liberty4 ,each herd of these animals has its definite dunging place at some convenient point4 ,that such herds have existed in the region from time immemorial is obvious from historical as well as collateral evidence2 and as their manure accumulated1 its nitrification would progress rapidly under the prevailing arid conditions4 ,the common salt would naturally be derived from the urine and excrements1 and the alkaline salts which exist throughout this region as the products of soil decomposition1 would be quite sufficient to account for the alkaline bases in the caliche4 ,on the other hand1 the presence of iodine points to seaweeds as the organic source4 ,intensity of ,nitrification in ,arid ,climates4--,of the efficacy of nitrification under arid conditions abundant evidence may be found within the ,state of ,california4 ,in the alkali lands of southern ,california the nitrates of soda1 lime and magnesia are almost universally present2 they form at times as much as one-fifth and even more of the entire mass of alkali salts1 and in one case the total amount in the soil has been found to reach two tons per acre1 with an average of twelve hundred pounds over ten acres4 ,in the plains of the ,san ,joaquin ,valley1 spots strongly impregnated with niter are found1 especially under the shadows of isolated oak trees1 where the cattle have been in the habit of congregating for a long time2 a case quite analogous to that supposed by ,kuntze to exist in the ,chilean locality4 ,of course it is only in arid climates that the accumulation of nitrates can usually occur2 for in the region of summer rains the nitrates formed during the warm season will inevitably be washed into the subdrainage1 unless restrained by absorption by the roots of vegetation4 ,the heavy losses occasionally occurring from this cause in the course of a rainy winter on summer-fallowed land have been amply demonstrated by many investigations4 ,,potash ,,minerals4--,by far the most abundant occurrence of potash in the earth's crust is that in silicates and notably in orthoclase or potash feldspar1 which contributes so largely to soil-formation4 ,but in the absence of any economically successful artificial method for producing potash compounds from feldspars on a commercial scale1 almost the entire supply of potash salts was1 until a comparatively late period1 derived from plant ashes1 viz41 the 8potashes0 of commerce4 ,at the same time1 almost the entire demand for alkalies for industrial uses bore upon the same product1 until the invention1 toward the end of the last century1 of ,le,blanc's process for the manufacture of soda from common salt2 for until that time1 soda in the various forms in which it was imported from the ,orient or prepared from seaweed ashes1 was a comparatively costly product4 ,le,blanc's invention was most timely in that it very quickly diminished materially the production of potashes which1 in view of the increased demand for alkalies for industrial uses1 seriously threatened the depletion of agricultural lands1 and of woodlands as well1 of one of its most essential ingredients4 ,yet as there are many industrial uses in which soda cannot replace potash1 the manufacture of potashes continued to a greater or less extent1 as no other available source except the ashes of land plants1 was then known4 ,the production of potassic chlorid from the mother-waters of sea salt in the spontaneous evaporation of sea water for the manufacture of common salt1 was on too small a scale to influence materially the manufacture of potashes4 ,discovery of ,stassfurt ,salts4--,the depletion of potash had become so serious a matter in the agricultural lands of ,europe1 that for a time much research was bestowed1 and prizes offered for an economical method of producing potash salts from feldspar1 on a commercial scale4 ,but the problem had not been satisfactory solved when1 in the year #ahfj1 attention was called to the fact that the saline deposits overlying certain large rock-salt beds that had been developed by borings near ,stassfurt in ,prussia1 contained so large a proportion of potash salts1 as to render their purification and conversion into fairly pure sulphate and chlorid technically feasible4 ,the impulse having been given1 the potash industry developed rapidly in that region as well as in the adjacent portions of ,saxony1 where the same formation underlies2 the production of 8,stassfurt ,salts0 rapidly assumed a greater development than that of the rock-salt which had originally prompted the enterprise1 and numerous additional boreholes demonstrated an unexpectedly wide extension of the same beds4 ,at the present time1 in consequence of such development1 the manufacture of potashes from plant ash has almost ceased1 outside of ,canada and ,hungary2 and the production of potash salts in the ,stassfurt region now supplies the demand of the entire world1 both for industrial and agricultural purposes4 ,the cheapening of potash as a fertilizer has rendered possible the profitable cultivation of large areas of land which were naturally too poor in that substance for ordinary cultures2 and has likewise rendered possible the restoration to general culture of lands that had ceased to produce adequately1 on account of the depletion caused by long-continued cropping4 ,it has likewise served to intensify agricultural production wherever desired2 and between this supply and that of phosphoric acid from the phosphorites 7see above71 and the discovery of the nitrogen-absorbing power of leguminous plants1 which can be used for green-manuring1 farmers have been enabled to dispense1 in many regions1 with the production and use of stable-manure1 which until then had been considered an indispensable adjunct to agriculture everywhere4 ,even within the last fifty years it was proclaimed by high authority in ,germany that stable-manure constituted1 as it were1 the farmer's raw material1 from which he manufactured the various products of the field through the intervention of the plant-producing power of the soil4 ,origin of the ,potash ,deposits4--,the manner in which this accumulation of potash salts has been formed deserves explanation4 ,it is abundantly evident that nearly all deposits of rock-salt thus far known have been formed by the evaporation of sea-water at times when bays or arms of the sea were cut off from open communication with the ocean4 ,the composition of sea-water has already been given and discussed 7chap4 #b1 p4 #bf72 and by the slow evaporation of sea-water on a small scale we can quite successfully imitate the phenomena observed in natural rock-salt deposits4 ,when sea-water is heated a slight deposit of lime carbonate 7usually containing a little ferric oxid and silica7 is soon formed2 and a corresponding thin deposit of ferruginous limestone is commonly found at the base of rock-salt-bearing deposits4 ,next above this we almost invariably find a deposit of gypsum1 sometimes of great thickness2 in the artificial evaporation of sea-water the same thing occurs so soon as the brine has reached a certain degree of concentration4 ,it constitutes the major portion of the 8panstone0 of salt-boilers4 ,next above follows a deposit of rock-salt1 at base somewhat mixed with gypsum2 its thickness varies greatly according to circumstances4 ,above it lie the potash salts4 ,in the manufacture of sea-salt by evaporation in shore lagoons or 8saltpans10 the solution remaining after the salt has been deposited 7known as 8mother-waters10 or 8bittern071 of course remains on the surface of the salt unless allowed to drain off1 as is done in the process of manufacture4 ,when not drained off1 the water gradually evaporates1 and there remains a saline crust of a composition exactly resembling that of the upper layers at ,stassfurt1 containing a large proportion of potash salts4 ,if it be asked why the ,stassfurt salts are not found overlying every rock-salt deposit in the world1 the answer is that in a great many cases the concentrated mother-waters have had an opportunity to flow off from the surface of the rock-salt by the action of tides1 the inflow of fresh water from the land or from other causes4 ,their presence therefore depends upon the fulfilment of accidental conditions not nearly always realized in the natural evaporation of sea-water1 but which happened to occur on a very large scale in that portion of the ,north-,european continent4 ,nature of the ,salts4--,the potash is present in the ,stassfurt salts in the form of complex sulfates and chlorids containing1 besides1 sodium1 calcium and magnesium in various proportions and modes of combination4 ,the most abundant of the potassic chlorid minerals is carnallite1 a hydrous chlorid of potassium and magnesium4 ,the chlorids characterize chiefly the upper portions of the deposit1 the sulfates the lower4 ,kainit4--,of the products derived from the ,stassfurt salt industry for agricultural use1 the two requiring special consideration are 8kainit10 a natural mixture of the several chlorid minerals in varying proportions2 and 8high-grade sulfate40 ,being a natural product1 8kainit0 is the cheapest source of potash available to the farmer2 but on account of its variability in composition it must be sold and purchased on guaranteed assay4 ,on account of its large content of chlorin it is not desirable in the production of certain crops1 especially in the arid region1 where alkali soils1 and even those not visibly alkaline1 often contain already large amounts of chlorin4 ,moreover1 kainit usually contains a considerable proportion of common salt4 ,for the arid region therefore the sulfate is generally preferable1 although it is somewhat higher in price for the same amount of potash4 ,the potash content of commercial kainit 7calculated as ,k,o7 ranges from #af to #ce1 while the sulphate frequently ranges from #hj up to #ie of the pure sulfate2 thus costing materially less in freight charges than the lower-grade kainit4 ,its potash content ranges from #dc to over #ej of ,k,o4 ,potash ,salts in ,alkali ,soils4--,the sulfates and chlorids of potassium1 however1 occur not only in connection with rock-salt deposits1 but are also found in the alkali soils of the arid region4 ,they are1 in fact1 never absent where such salts occur at all1 and their percentage in the total of salts ranges all the way from about #d to as much as #bj of potash sulphate4 ,in numerous cases it has been found that the content of this salt to the depth of four feet amounts to from #abjj to #aejj pounds per acre4 ,in such lands1 of course1 additional fertilization with potash salts is totally uncalled for1 the more as such soils invariably contain1 besides the water-soluble potash1 an unusually large percentage of the same in the form of easily decomposable silicates1 or zeolites4 ,farmyard or ,stable ,manure4--,in connection with the subject of mineral fertilizers1 it will be proper to discuss briefly the uses and special merits of stable manure1 composts1 etc4 ,up to within the last century1 these were practically the only fertilizers known and used1 and the exclusive use of this manure might have continued indefinitely but for the discovery that as time progressed1 stable manure and with it grain crops1 for the production of which it was necessary1 became less and less in amount1 so as to threaten bread famines4 ,the cause of this diminution was1 of course1 the incompleteness of the return of the soil-ingredients taken off by the crops1 when these were exported to feed the cities or foreign countries4 ,thus the attention of chemists1 and notably that of ,liebig1 was attracted to the solution of the problem of keeping up production even with an insufficient supply of stable manure2 and the discovery of the use of mineral fertilizers was the result of their activity4 ,the chemical composition of stable manure does not1 alone1 suffice to explain its remarkable efficacy and the difficulty of replacing it by any other material4 ,the composition of manure of course differs not only with different animals but also with the different feeds consumed by them2 but the average composition of farmyard manure is approximately given thus by ,wolff and others3 ,,analyses ,,of ,,various ,,farmyard ,,manures4 #a4 #b4 #c4 #d4 #e4 ,water #ga4jj #ge4jj #gi4jj #gi4ie #gb4cc ,dry ,matter #bi4jj #be4jj #ba4jj #bj4je #bg4fg ,ash ingredients #d4dj #e4hj #f4ej #e4hg ,potash #j4eb #j4fc #j4ej #j4hdbc #j4fi ,lime #j4eg #j4gj #j4hh #j4he ,magnesia #j4ad #j4ah #j4ah #j4ad ,phosphoric acid #j4ba #j4bf #j4cj #j4dj #j4cj ,ammonia #j4jb ,total ,nitrogen #j4de #j4ej #j4eh #j4gh #j4df ---------------------------------------- -------------- #a4 ,average composition of fresh farm manure 7,wolff74 #b4 ,average composition of moderately rotted farm manure 7,wolff74 #c4 ,average composition of very thoroughly rotted farm manure 7,wolff74 #d4 ,mixed cow and horse manure from a bed two feet thick1 accumulated during the winter in a large covered yard1 and packed solid by the tramping of cattle 7,the analysis by ,f4 ,e4 ,furry74 #e4 8,box ,manure10 consisting of mixed manure of bullocks1 horses1 and pigs 7,way1 ,royal ,agric4 ,soc4 ,journ41 #ahej1 ,,ii41 #gfi74 #bc ,and soda4 ,it is thus seen that the percentage of the important plant-foods in stable manure are minute when compared with those commonly found in 8commercial0 fertilizers4 ,nor are they so much more available for plant absorption than the latter2 a very large proportion is not utilized at all the first year1 and unless the amount applied is very large it hardly carries the supply needed for the usual crops4 ,it is now well understood that its efficacy is largely due to the important physical effects it produces in the soil4 ,it helps directly to render heavy clay soils more loose and readily tillable4 ,if well 8rotted0 or cured it also serves to render sandy1 leachy soils more retentive of moisture2 and the humus formed in its progressive decay imparts to all soils the highly important qualities discussed later on 7chapt4 #h74 ,more than this1 the later researches have shown that stable manure acts perhaps most immediately upon the bacterial activity in the soil1 greatly increasing it not only directly by the vast numbers of these organisms it brings with it1 but also in supplying appropriate food for those normally existing in the soil 7see chapt4 #i74 ,in so doing it serves indirectly to render the soil ingredients more available1 and to impart to the soil the loose condition required in a good seed-bed--a 8tilth0 which cannot be brought about by the operations of tillage alone4 ,the only possible substitute for the use of stable manure is found in green-manuring with leguminous crops conjointly with the use of commercial or mineral fertilizers4 ,unless this is done the use of the latter1 alone1 ultimately leads to a depletion of humus substances1 which renders the acquisition of proper tilth by the seed-bed impossible1 and causes a compacting of the surface soil which no tillage can remedy4 ,proper method of using stable manure in humid and arid climates4--,in the humid region it is a common practice to spread the stable manure on the surface of the fields and leave it there without any special operation to put it into the soil2 trusting to the rains1 earthworms and subsequent tillage for its being brought into adequate contact with the roots2 it is rarely plowed in4 ,in the arid region this mode of using it is impracticable2 it would remain on the surface indefinitely without advancing in its decay because of the dryness1 and unless plowed in very deep the ordinary1 strawy manure would ruin the seed-bed by rendering it too pervious to the dry air1 thus preventing germination4 ,much of this valuable material has therefore been1 and to some extent is still being burnt1 thus causing a severe depletion of the land1 both of humus and of mineral plant-food4 ,the best way to deal with stable manure in the arid regions is to thoroughly rot or cure it before putting it on the land1 and then plowing it in4 ,to do this of course it must be put in piles and wetted regularly2 a procedure which at the high prices of labor is thought to be too expensive1 but which in the end would be found eminently profitable1 unless green-manuring is regularly done4 ,the very small proportion of humus generally present in arid soils renders this precaution indispensable1 if production and proper tilth is to be maintained4 ,the saving of stable manure and of all composting material1 even if less needful as a means of supplying plant-food in the rich soils of the arid regions1 is fully as essential in order to maintain the humus supply4 7,b47 ,,minerals ,,unessential ,,or ,,injurious ,,to ,,soils4 ,the minerals heretofore mentioned contribute to soil formation either one or several ingredients1 important to plant growth either by their mechanical or chemical action4 ,it remains to consider some not intrinsically desirable1 but frequently present in certain soils1 which should be known to the farmer in order that he may be enabled to counteract or remove their injurious effects4 ,leaving aside such as are of only casual or rare occurrence1 the following may be mentioned as among those which not unfrequently affect soils desirable for culture to such extent as to make them unavailable for general farming purposes3 ,iron ,pyrite2 sulphid of iron containing two molecules of sulphur to one of iron2 a mineral exceedingly common in deposits of metallic ores1 and whose deceptive gold-like color has caused it to be mistaken for gold so often as to cause it to be designated as 8fool's gold0 among miners4 ,while it frequently does contain some gold and is often associated with valuable ores1 it is practically valueless when occurring outside of mineral veins1 in rock-masses2 and more especially in sedimentary rocks1 such as sandstones1 limestones1 shales and clays4 ,when present in soils it sometimes becomes a source of trouble to the farmer1 because in contact with air it is soon transformed into ferrous sulfate or copperas1 which1 like the carbonate referred to above1 is injurious to plants4 ,sometimes indeed iron pyrite is actually formed in badly-drained soils alongside of the carbonate of iron1 when much sulfate 7such as gypsum7 is present2 and then its injurious effects subside more slowly than do those of the carbonate 7see above1 p4 #df74 ,recognition of ,iron pyrite4--,the mineral is easily recognized by its golden or brass-yellow tint2 the latter color being the one most commonly shown in the 8sulphur balls0 occurring in marls or soft limestones4 ,a very easy test is to pulverize it and then heat it on a shovel over a fire1 when it will soon itself take fire1 burning with a blue sulphur flame1 and upon more complete roasting1 leaving behind a red powder1 viz41 8,venetian red0 or red ochre2 that is1 ferric oxid4 ,in clays it commonly occurs in large1 well-defined cubes1 which do not readily form copperas but rather become covered with a crust of limonite or brown iron ore4 ,when a subsoil is found to contain pyrite1 or when 8sulfur balls0 have been accidentally introduced with dressings of marl1 the remedy is thorough and persistent aeration of the material4 ,in the case of marls nothing more need be done2 but in that of ill-drained subsoils it is best to add lime in moderate dressings1 to accelerate the transformation into ferric hydrate or iron rust1 and gypsum2 whereby the copperas becomes not only innocuous but adds two beneficial ingredients to the soil4 ,the same policy will render available manure or other materials which have been disinfected by means of solution of copperas4 ,halite 7rock-salt71 or common salt1 has already been mentioned as to its occurrence in connection with the ,stassfurt potash salts 7see above1 page #ga72 but as rock-salt it rarely exerts any injurious influence upon lands4 ,it is1 however1 a common ingredient of seashore lands1 and is also present to a certain extent in the alkali lands of the arid countries4 ,while it is true that occasionally small quantities of common salt are used as an ingredient in fertilization1 its usefulness in that direction is exceedingly subordinate2 and it is far more generally to be considered as an injurious ingredient of all cultivatable soils whenever present to a larger extent than a few hundredths of one per cent ,it is usually considered that one-fourth of one per cent of common salt renders lands unfit for most culture plants4 ,only a few1 such as asparagus1 the beet1 the saltbushes and some others1 succeed when it is present in this or in larger amounts4 ,in the case of sea water it is usually accompanied by a still more injurious ingredient1 magnesic chlorid or bittern2 which is detrimental to plant growth in much smaller quantities than the common salt itself4 ,recognition of ,common ,salt4--,the presence of common salt may1 as a rule1 be detected by the taste1 well-known to every one2 when this taste is very intense or somewhat bitterish1 it indicates the presence of bittern4 ,the presence of salt1 however1 is easily verified without the use of chemical reagents1 by slowly evaporating some of the clear water leached from the soil in a clean silver spoon4 ,if the last few drops are allowed to evaporate spontaneously1 it will be easy to distinguish1 even with the unaided eye1 the square1 cubical crystals1 sometimes combined into cross-shape1 which are characteristic of common salt4 ,it is always an unwelcome addition to the land1 and as its action cannot be neutralized in any way1 it can be gotten rid of only by leaching-out4 ,this process is usually accomplished in seashore lands by the action of rain1 or by the overflow of fresh-water streams1 after the tide has been excluded by means of drains provided with check-valves to prevent the inflow of tidewater2 or else by underdrainage1 and flooding when possible4 ,mirabilite1 7,glauber's salt7 or sulfate of soda1 exists not unfrequently in the soils of the arid region and sometimes encrusts extended areas of lowlands during the dry season4 ,when present in the soil it will commonly be seen blooming out on the surface after a rain1 in light1 feathery1 needle-shaped crystals1 sometimes to such an extent that it can be collected by the handful4 ,subsequently1 when wafted by the wind1 it is reduced to a fine white dust1 which constitutes a goodly proportion and sometimes the entire mass of the 8alkali dust0 that is so annoying on the plains of ,nevada1 and in the desert regions generally1 during the hot summer4 ,near ,white ,plains1 ,nevada1 it forms a thick layer of 8white sand10 in which the foot sinks deeply1 and which is carried about by the wind with great ease4 ,glauber's salt is never a desirable soil-ingredient4 ,it is largely produced as a by-product in several industries1 but cannot be utilized for agricultural purposes to any extent4 ,it is1 however1 much less injurious to plant growth than common salt2 according to experience in ,california it may be considered about three times less so4 ,it constitutes the major portion of what is commonly known as 8white alkali10 which is well known to be much less injurious to crops than the 8black0 kind1 which contains carbonate of soda4 ,trona and ,urao are natural forms of carbonate of soda or salsoda4 ,like ,glauber's salt1 it commonly occurs as a surface efflorescence or crust in dry or desert regions2 either from the evaporation of standing water1 as in the case of the soda lakes of ,nevada1 ,hungary and ,egypt1 or as an efflorescence on the surface of the soil1 as in the western ,united ,states1 ,mexico 78urao071 ,north ,africa 78trona071 and at many points in the ,old ,continent4 ,in the ,united ,states it is commonly known as 8black alkali10 because of the black spots formed on the surface by evaporation2 practically the same name 78kara07 is given it in ,arabia and ,asia ,minor1 whence impure soda has long been imported into ,europe2 while in north ,india it forms part of the 8reh0 salts that incrust large areas 7usar lands7 in the ,indo-,gangetic plain4 ,the natural mineral always contains an excess of carbonic acid over the 8normal0 salt1 nearly in the proportion of four parts of carbonic dioxid to three of soda2 it is sometimes designated as sesqui-carbonate4 ,in hot sunshine it may lose most of this excess for a time2 while within the soil itself it may1 in presence of abundant carbonic acid1 become temporarily converted wholly into hydrocarbonate or 8bicarbonate10 which is less corrosive than the monocarbonate or common salsoda4 ,injury caused in soils4--,like common and ,glauber's salt1 carbonate of soda is always an unwelcome soil ingredient2 more so1 in fact1 than either of the other two1 since less than a tenth of one per cent is sufficient to render certain soils wholly untillable1 by the deflocculation or puddling of the clay2 at the same time rendering it impervious to water4 ,it is by far the most injurious ingredient that ordinarily occurs in otherwise good1 arable soils2 for in addition to the physical effect just mentioned1 it dissolves the humus-substance of the soil1 forming an inky-black solution which1 especially when evaporating on the surface and forming black spots1 has given rise to the popular name of 8black alkali40 ,as will be more fully explained hereafter1 wherever such is the case1 the first step necessary toward reclamation is the transformation of the carbonate of soda1 at least in part1 into the relatively innocuous sulfate1 by means of gypsum in the presence of water2 while carbonate of lime remains in the soil4 ,in its direct action on the plants themselves1 soda is also most injurious2 as when accumulated to any extent near the surface by evaporation it will corrode the root-crown or stem1 and sometimes completely girdle the same1 destroying the bark4 ,farther details on this subject are given in chapter #bb4 ,epsomite1 or ,epsom salt1 or sulfate of magnesia1 is another one of the water-soluble minerals frequently found efflorescent on the surface of the ground2 more commonly in saline seashore lands than in the alkali region proper1 although it is rather common in the northeastern portion of the arid region of the ,united ,states4 ,whether on the soil surface or in the crevices of rocks1 its needle-shaped1 feathery crystals greatly resemble those of ,glauber's salt1 but are readily distinguished by the more intensely bitter taste4 ,epsom salt is frequently the last remnant of sea-salts left in the soil after reclamation4 ,though probably somewhat more injurious to plant growth than ,glauber's salt1 the mineral ,kieserite1 one of the ,stassfurt salts and consisting essentially of ,epsom salt1 is sometimes used as an application to calcareous lands instead of gypsum1 and with good results4 ,yet gypsum is usually the safer1 and equally effective4 ,borax 7bi-borate of soda7 occurs much more rarely than the salts just described2 most frequently in certain portions of ,california1 forming part of the 8alkali0 in the soil4 ,it is injurious to plant growth1 but is as readily dealt with as is the carbonate of soda1 by dressings of gypsum1 whereby inert borate of lime is produced4 ,it is hardly necessary to say that saline waters containing any of the above salts in notable amounts must be used for irrigation very cautiously4 ,the measures to be observed in this respect will be discussed later4 ,,part ,,second4 ,,physics ,,of ,,soils4 ,,chapter ,,vi4 ,,physical ,,composition ,,of ,,the ,,soils4 ,as has already been stated 7chapt4 #a1 p4 #aj71 the general physical constituents of soils are rock powder or sand and silt1 more or less decomposed according to the nature of the original rocks2 clay1 the product of the decomposition of feldspars and some other silicates2 humus1 the complex product of the decomposition of vegetable and animal matters on and in the soil mass2 as well as vegetable matter not yet humified4 ,each of these several constituents must now be considered more in detail4 ,since clay is the substance whose functions and quantitative proportions influence most strikingly the agricultural qualities of land1 it should be first discussed4 ,clay as a ,soil ,ingredient4 ,the plasticity and adhesiveness of clay1 together with the extreme fineness of its ultimate particles 7said to reach the #a-bejjj of an inch71 explains its great importance as a physical soil ingredient4 ,it serves to hold together and impart stability to the flocculent aggregates of soil particles that compose a well-tilled soil2 for without clay the sand would collapse into close-packed single grains so soon as dried1 and loose tilth would be impossible4 ,sand drifts illustrate this condition4 ,on the other hand1 the fineness of the particles serves to render clay very retentive of moisture as well as of gases and of solids dissolved in water1 imparting these important properties to soils containing it2 while coarse sandy soils are oftentimes so deficient in them as to render them unadapted to any useful culture1 despite the presence of an adequate supply of plant-food4 ,when to these essential physical properties of clay1 there is added the fact that usually the clay-substance as it exists in soils contains the most finely pulverized and most highly decomposed portions of the other soil-minerals1 and therefore the main part of the available mineral plant-food1 it is easy to understand why soils containing a good supply of clay should be called and considered 8strong0 land by the farmers of all countries4 8,poor0 clay soils are exceptional2 but sometimes the clay content reaches such a figure that the difficulties of tillage render them too uncertain of production for profitable occupation4 ,amount of ,colloidal ,clay in ,soils4--,any and all of the kinds of clay mentioned 7p4 #eg7 as occurring naturally may1 of course1 enter into and form part of soils4 ,but as the amount of true1 plastic clay substance contained in them is very indefinite1 it becomes necessary1 in order to classify soils in respect to their tillableness1 to ascertain more definitely the amount of pure1 or nearly pure1 colloidal clay substance contained in the several classes of soils ordinarily recognized and mentioned in farming practice4 ,that this determination can at best be only approximate1 is obvious from the fact mentioned above 7chapt4 #d1 p4 #ei71 that pure kaolinite itself is not plastic1 and only becomes so by the indefinite comminution and hydration it experiences in the processes of soil-formation4 ,as the progress of this process is also indefinite1 the same soil containing particles ranging from the finest to the chalky scales of pure kaolinite1 the drawing of a line must be more or less arbitrary and empirical4 ,from numerous experiments and comparisons made1 the writer has been led to place the limits of 8plastic clay0 at and below such grain sizes as will remain suspended 7afloat7 in a water column eight inches high1 during #bd hours4 ,to go beyond this point in the examination of soils for practical purposes1 would render such examinations so laborious and hence so rare1 that this kind of work would be practically excluded from ordinary practice4 ,according to this view the following percentages of such 8clay0 correspond approximately to the designations placed opposite3 ,very sandy soils 4#e to #c clay ,ordinary sandy lands #c4j to #aj 8 ,sandy loams #aj4j to #ae 8 ,clay loams #ae4j to #be 8 ,clay soils #be4j to #ce 8 ,heavy clay soils #ce4j to #de and over4 ,it must be distinctly understood1 however1 that these figures make no claim to accuracy or invariability4 ,for1 the tilling qualities of a soil containing one and the same amount of such 8clay0 may be very materially modified according to the kind and amount of each of the several grain-sizes of rock powder or sand they contain4 ,influence of fine powders on plasticity and adhesiveness4--,an admixture of a large amount of fine powders diminishes materially the adhesiveness of a clay soil1 even though it may render it even more 8heavy0 in tillage2 while the admixture of coarse sand1 even in very considerable proportions1 does not greatly influence the adhesiveness of the clay4 ,the latter alone cannot therefore serve as a proper guide or basis for the classification of soils in respect to tillage2 we must also take into consideration the nature and amount of the several granular sediments mixed with it4 ,moreover1 the nature and especially the adhesiveness of the clay substance as obtained by analysis may vary considerably in the presence of a very large amount of the finest grain-sizes2 among which ferric hydrate or iron rust is especially apt to accumulate predominantly in the clay1 considerably increasing its apparent weight and greatly diminishing its adhesiveness4#bd ,in strongly ferruginous soils1 therefore1 it becomes necessary to take into special consideration the amount of the ferric hydrate or rust which accumulates in the clay substance4 ,the presence of large amounts of humus or vegetable mold also influences materially the adhesiveness and physical properties of the clay obtained by the method described1 although most of it remains with the finer powdery sediments or grain-sizes4 ,there are1 besides1 other colloidal or at least amorphous substances present in all soils1 such as silicic1 aluminic and zeolitic hydrates1 which are all non-plastic1 and yet sufficiently fine to form part of the 8clay0 obtained as above specified4 #bd ,this fact emphasizes the impossibility of explaining the plasticity and adhesiveness of clay simply as a function of fineness of grain4 ,despite these imperfections1 7which however can in a measure be taken into consideration in judging of a soil's tilling qualities by its clay content71 the figures given in the above table approximate much more nearly to a tangible basis for such estimate1 than the utterly indefinite mixtures which under the older methods of analysis have been1 and still are to some extent1 used as a basis for soil classification by writers on agriculture4 ,rock ,powder2 ,sand1 ,silt and ,dust4 ,the powdery 7sandy and silty7 constituents of soils usually constitute the greater part of their mass2 and the proportions present of the several grades of fineness exert a most decisive influence upon their cultural qualities1 and very commonly upon their agricultural value also4 ,it is needless to add that the kind of mineral of which they consist or from which they were formed1 is also of great importance in determining the quality of soils from the standpoint of the chemist1 with respect to their content of mineral plant-food4 ,,weathering ,,in ,,humid ,,and ,,arid ,,regions4 ,sands of the ,humid ,regions4--,as has already been stated1 8sand0 is usually understood to be1 in the main1 quartz more or less finely pulverized1 generally intermingled with a few grains of other minerals4 ,with this understanding1 since quartz is practically inert with respect to plant nutrition1 it follows that soils consisting mainly of this substance contain but little plant-food2 hence the common expression 8poor1 sandy land10 the outcome of the experience had in ,europe and in the ,eastern ,united ,states1 and which until recently has been held to be of general application4 ,the 8sands of the desert0 have1 both in ordinary life and in poetry1 always stood as the symbol of sterility4 ,thus the sandy lands 78sand hammocks07 of ,florida1 the 7long-leaf7 pine lands of the ,gulf ,states1 the 8pine barrens0 of ,new ,jersey and of ,michigan1 are noted both for their sandy soils and their sterility after brief cultivation2 necessitating fertilization within a few years from the time of occupation4 ,in ,europe1 the 8,heide0 7heather7 soils of northeastern ,germany are of the same cultural character4 ,sands of the ,arid ,regions4--,the experience of arid countries however1 has long ago shown that some very sandy lands--e4 g41 such as form the oases of the north ,african deserts--may be extremely productive when irrigated1 and also of considerable durability4 ,actual experience and close investigation given this subject in the arid regions of the ,united ,states has fully demonstrated that lands appearing to the casual observer to be hopelessly sterile sandy deserts1 very commonly prove to be even more productive than the more clayey lands of the same regions4 ,examination of the sand shows1 in these cases1 that instead of mere grains of quartz1 the minerals of the parent rock1 partially decomposed1 themselves constitute a large proportion of the sandy mass4 ,but in the regions of deficient rainfall1 as has already been stated1 7p4 #dg7 the formation of clay 7kaolinization7 is exceedingly slow2 hence the decomposition of the rock powder results in the production of predominantly pulverulent instead of clayey soils4 ,but the mineral plant-food is not on that account less available1 provided other physical conditions necessary for the success of plant growth are fulfilled4 ,among these moisture stands foremost2 hence the relative proportions of the several grain-sizes are of vital importance1 since upon this depends to a great extent the proper supply and distribution of moisture1 without which no amount of plant-food will avail4 ,moreover1 the finest and most highly decomposed powder is the portion from which the roots draw their chief food-supplies4 ,the point last mentioned is well shown in the results obtained by ,dr4 ,r4 ,h4 ,loughridge1 from the analysis of each of the several grain-sizes into which he had resolved a very generalized soil of the ,state of ,mississippi1 representing a very large land area in that ,state as well as in ,tennessee and ,louisiana4 ,the details of this investigation are given farther on2 but summarily it may be stated that he found practically the whole of the acid-soluble mineral plant-food accumulated within the portion of the soil the fineness of whose grains was below 4#jbe millimeters 7one-thousandth of an inch72 ingredients so fine as to be wholly impalpable between the fingers4 ,moreover1 two-thirds of the total amount was found in the portion described above as 8clay40 ,it is thus readily understood why clay soils are in the regions of summer rains commonly designated as 8strong0 lands4 ,the corresponding later investigations of ,rudzinski 7,ann4 ,agr4 ,inst4 ,moscow1 ,vol4 #i1 ,no4 #b1 pp4 #agb-bcd2 ,exp4 ,sta4 ,record1 ,dec4 #aijd1 p4 #bde7 and of ,mazurenko 7,jour4 ,exp4 ,landw4 #aijd1 pp4 #gc-ge2 ,exp't ,stn4 ,record1 ,dec4 #aijd1 p4 #cdd7 fully corroborate ,loughridge's conclusions1 for typical soils of ,european ,russia4 ,in the arid or irrigation regions1 however1 the case is different1 for the reason that much of the decomposed rock-substance remains adherent to the surface of the larger grains1 and plastic clay is formed to a much less extent4 ,much available plant-food may therefore1 in arid lands1 be present even in rather coarsely sandy soils almost devoid of clay2 such as in humid climates would be likely to be found wholly barren4 7,see chapt4 #ai74 ,,physical ,,analysis ,,of ,,soils4 ,use of ,sieves4--,down to a certain point the separation of the soil into its several grain-sizes may be accomplished by means of sieves4 ,we may thus separate coarse gravel from fine gravel and from sand2 and the latter may itself be separated into several sizes by the same means4 ,this presupposes1 of course1 that the soil has been previously prepared for the purpose by crushing the lumps consisting of aggregates of finer particles1 that in the operation of tillage would again be resolved into their fine constituents1 or be penetrated by roots4 ,but this preparation of the soil for sifting must not be carried beyond the point mentioned1 for a grain consisting of particles somewhat firmly cemented together will under ordinary conditions play in the soil precisely the same part as a solid sand-grain1 and must not therefore be broken up1 if the soil is to be examined in its natural condition4 ,the pressure of the fingers or of a rubber pestle is as far as trituration should go4 ,the disintegration of these compound particles by means of acids1 as prescribed and practiced by the ,french soil chemists1 may wholly change the physical nature of the soil by the breaking-up of mechanical aggregations which in the usual course of tillage would remain intact4 ,this is especially true of strongly calcareous soils1 and particularly those containing calcareous sand4 ,the sieves used for this purpose should not be ordinary wire sieves1 but should have bottoms of sheet brass perforated by round holes of the various diameters desired1 of fractions of inches1 or preferably of millimeters4 ,for the finer grain sizes1 silk bolting cloth is used by the ,u4 ,s4 ,bureau of ,soils4 ,in the sifting process it will be found that so soon as the finer grain-sizes of the sand are approached1 the sieve fails to act satisfactorily2 the more so1 the more clay was originally contained in the material4 ,the fine particles flock together1 forming little pellets1 which refuse to be separated by the sieve4 ,this difficulty can1 of course1 be partly overcome by previously separating the clay from the sand by means of water1 as detailed above2 but even then it will be found that so soon as the grain-sizes fall much below _/ of an inch 7 millimeter7 the same difficulty is experienced1 so long as the sand is dry4 ,by playing a small stream of water upon the sieve1 however1 all the particles beyond the _/ of an inch may be successfully separated from the coarser portion2 and for many practical purposes the separation need be carried no farther4 ,use of ,water for ,separating ,finest ,grain-,sizes4--,the scientific investigator1 however1 must of necessity proceed to separate the finer grain-sizes from each other1 since1 as will presently be shown1 they influence the tilling qualities of the soil to a much greater degree than do the coarser particles4 ,such farther separation can be accomplished only by the aid of water4 ,subsidence ,method4--,when a small amount of soil is stirred up in water1 and is afterward allowed to stand for some time1 the different grain-sizes will settle consecutively in accordance with their sizes 7or weights72 the smallest ones settling latest1 and the clay only remaining suspended1 as stated above4 ,so long1 however1 as any considerable amount remains suspended in the water1 the latter is not only denser but especially more viscid than if the clay were absent4 ,in order therefore to obtain correct results by any method involving the use of water1 it is necessary to remove the clay before proceeding to the separation of the granular sediments4 ,this1 as has been already stated1 is approximately accomplished by allowing the soil1 when diffused in water after proper disintegration1 to settle for #bd hours from a column of water #bjj mm4 high1 whereby all grain-sizes1 of and above 4#ja mm4 diameter are removed from the turbid liquid4 ,this sedimentation is then repeated until after #bd hours the water becomes clear4 ,the clay is then determined in the 8clay water0 by evaporation or precipitation2 the granular sediments may then be successfully separated by sedimentation4 ,the ,u4 ,s4 ,bureau of ,soils uses for the separation of clay1 instead of subsidence for #bd hours1 the more expeditious process of centrifuging the turbid soil water in appropriate glass cylinders1 by the aid of an electric motor2 and thus in a relatively short time obtains 8clay0 in which the upper limit of size is one-half of that mentioned above1 viz41 4#jje mm4 ,but for the costliness of the appliances required1 including the entire time of an operator1 this method of separating the clay would undoubtedly be preferable to the elimination by subsidence2 the more as a more minute grain-size for the clay group is thus secured4 ,illustration3 ,,fig4 #f4--,schne's ,elutriator4 ,the separation of the clay having been accomplished1 the various sizes of silt and sand may be separated by again suspending them in water2 and interrupting the settling process at stated times1 the grain-sizes corresponding to definite velocities in settling may be segregated and weighed4 ,when this process of settling and decanting is carefully and repeatedly carried out1 very good results are obtained4 ,hydraulic ,elutriation4--,the sedimentation 7or 8beaker07 method1 long practiced in the arts is1 however1 quite tedious1 requiring the constant close attention of a skilled observer4 ,the desired results may1 in the writer's judgment1 be more conveniently obtained by the hydraulic method1 whenever no very large volume of work of this kind is required to be done at once4 ,when instead of allowing the soil to settle in quiet water1 the latter is used as an ascending current of regularly graded velocities1 it is clear that the soil particles will be carried off by this current in exact conformity with their several sizes 7or strictly speaking1 volume-weights72 and when maintained in such a current for a sufficient length of time1 the entire quantity of the sediment corresponding to the prevailing velocity will be carried away4 ,it is of course easy to ascertain to what grain-sizes certain velocities of the upward current 7regulated by a stopcock with arm moving on a graduated scale7 correspond1 and to regulate accordingly the intervals between the different velocities to greater or less detail1 as may be desired4 ,a number of instruments have been devised for this purpose4 ,schne's ,elutriator is the one commonly used in ,europe2 in it the upward current ascends in a conical glass tube1 7see figure #f7 entering through a narrow1 curved inlet tube1 in which the soil sample is kept agitated by the current itself4 ,the objection to this plan is twofold3 first1 the narrow1 curved inlet-tube is readily clogged by the soil mass at the lower velocities1 which are thereby changed1 so that1 unless a very small amount of soil only is employed1 the whole mass is not kept properly stirred2 second1 the circulating currents brought about by the conical shape of the tube cause the sediment-particles to coalesce into complex1 larger ones 7floccules71 which will then settle down and fail to pass over at the current-velocity corresponding to their individual component parts4 ,illustration3 ,,fig4 #g4--,the ,churn ,elutriator 7,hilgard's7 for the physical analysis of soils4 ,churn ,elutriator with ,cylindrical ,tube4--,the errors just alluded to are obviated by an arrangement devised by the writer1 in which a rapidly revolving stirrer1 placed at the base of a cylindrical tube in which the washing process is conducted and which eliminates counter-currents1 continually disintegrates these compound particles1 and thus enables the entire quantity of the sediment corresponding to the prevailing current-velocity to pass off with a comparatively slight expenditure of time on the part of the operator 7see figure #g74 ,a wire screen interposed between the churn and cylindrical glass tube prevents communication of the whirling motion to the column4 ,as the apparatus works automatically1 the analyst has only to observe from time to time whether or not the turbidity near the top of the tube has disappeared2 and as the sediment accumulates at the bottom of the tall receiver bottle1#be no harm is done if the attendant should neglect to change the velocity in time1 except that water will run to waste4 #be ,the figure given of this elutriator in ,bulletin ,no4 #bd1 on physical soil analysis1 published by the ,u4 ,s4 ,bureau of ,soils1 shows as the receiver a bottle entirely too low to insure the complete retention of the sediments by settling4 ,the receiving bottle should not be less than twelve inches high and five inches wide4 ,the conical relay glass below the churn serves to retain the coarser grades of sediments which are not concerned in the velocities employed in the elutriator tube1 and thus prevents injurious attrition4 ,but these sediments can at any time be stirred up by the incoming current and brought into the washing tube if desired4 ,in the same manner the passing-off of the finer sediments can be materially accelerated by running off rapidly about two-thirds of the turbid column of water every twenty minutes4 ,it should be fully understood that prior to attempting such separation1 the 8colloidal clay0 must first be removed by the subsidence or centrifugal method1 since otherwise much larger grain-sizes may be carried off at a given velocity4 ,yoder's ,centrifugal ,elutriator4--,a very ingenious instrument which combines the elutriation and sedimentation processes into one1 has been devised by ,p4 ,a4 ,yoder1 of the ,utah ,expt4 ,station4 ,the elutriator bottle is placed in a centrifuge driven by an electric motor2 it is closed by a glass stopper carrying a delivery tube to a short distance above the bottom of the elutriator bottle1 as well as an outflow tube ending at the base of the stopper2 the latter also carries a funnel coinciding with the center of rotation4 ,into this funnel flows gradually the muddy water containing the soil in suspension2 and the rate of its flow1 together with the velocity of rotation1 determines the size of the sediment-granules that will be deposited in the slack-water below the mouth of the delivery tube4 ,the muddy soil-water is kept agitated in a funnel-shaped reservoir by air-bubbles from a constant-pressure chamber4 ,while the principle of this instrument is good1 it is quite complicated and the results obtainable from it in practice have not as yet been made public4 ,the inventor claims that an analysis may by its means be completed in less than three hours4 ,in all hydraulic elutriators a provision for constant pressure in the reservoir supplying the current of water is needed2 although in ,schne's and some other instruments a gradually decreasing pressure in a plain reservoir is employed4 ,a large glass bottle or carboy fitted with the proper tubes so as to constitute a ,mariotte's bottle 7in which the air enters near the bottom of the vessel71 is a very convenient arrangement4 ,number of ,sediments4--,the number of grain-sizes or sediments into which the soil mass is to be segregated is of course entirely within the option of the operator4 ,experience has shown that it is unnecessary to discriminate very closely between the several sizes of the coarser portion of the sand1 such as those lying between one-fourth and one-half of a millimeter4 ,but below this point1 and especially between one-tenth of a millimeter and the clay1 a proper discrimination becomes very important4 ,the series first devised by the writer in #ahgb is based upon a consecutive doubling of the velocities of the current from a quarter of a millimeter per second to thirty-two millimeters per second2 the sediment of sixty-four millimeter-velocity corresponding to a diameter of one-half of a millimeter1 will remain in the elutriator4 ,above this1 as before remarked1 the sieve 7especially when aided by a jet of water7 effects a satisfactory segregation4 ,the table below shows the elements of these series both as regards current-velocities and maximum quartz-grain diameters carried off by each4 ,in a great many cases1 however1 it is altogether unnecessary to go into such detail1 and a subdivision into six or seven divisions is quite sufficient4 ,such a subdivision1 based upon the doubling of grain-sizes instead of current-velocities1 has been adopted by ,prof4 ,milton ,whitney1 of the ,u4 ,s4 ,department of ,agriculture1 and others4 ,,table ,,of ,,diameters ,,and ,,hydraulic ,,values ,,of ,,sediments4 ,velocity per second1,maximum diameter ,designation of materials4 or hydraulic of quartz value4 grains4 ---------------------------------------- --------------------- ,mm4 ,mm4 ,grit 787 #a-c 787 4#e-a #cb-fd 4#ej ,sand #af-cb 4#cj #h-af 4#af #d- #h 4#ab #b- #d 4#jgb #a4j- #b 4#jdg ,silt 4#e- #a 4#jcf 4#be-j4e 4#jbe #j4be 4#jaf #j4be 4#jaj ,clay #j4jjbc ---------------------------------------- --------------------- ,results of such analyses4--,a tabular presentation of the results of analyses made in accordance with the above plan will give a good idea of the differences between the various grades of soils recognized in farm practice1 to any one accustomed to the study of figures4 ,but a much more satisfactory showing is made by placing the several grain-sizes segregated1 into small vials or tubes of identical diameter and placing them in parallel series alongside of each other4#bf ,the curves formed by the surfaces of the several sediment-columns in each series show to the eye very strikingly the relations of the several grades of soils to each other1 and suggest at once that while gentle slopes or gently undulating curves belong to soils of intermediate1 loamy character1 steep grades and zigzags show soils of extreme types4 ,this is exemplified in the subjoined ,figures3 #bf ,convenient stands for this purpose1 used by the writer since #ahgb1 may be cut from ,l-shaped moldings of wood1 such as can be readily ordered from any planing mill4 ,the vials can be cemented1 wired or tied4 ,illustration3 ,,fig4 #h4--;,illustration of ,results of ,hydraulic ,elutriation1 showing extremes of soil texture1 and intermediate loam4 ,illustration3 ,,fig4 #i4--;,illustration of ,results of ,hydraulic ,elutriation1 showing ,alluvial ,silts and ,pine-,woods ,soil4 ,physical composition corresponding to popular designations of ,soil quality4--,the subjoined table illustrates the physical composition of a number of soils from the ,state of ,mississippi1 selected for their representative character1 in order to deduce therefrom approximate definitions of physical character corresponding to popular designations4 ,this table1 published in #ahgc in accordance with results obtained during the two preceding years1 does not require any material modification on account of subsequent investigations4 ,it lacks1 however1 a characteristic representative of the predominant soils of the arid region1 viz41 the silty soils so prevalent in dry climates1 only approximately represented by ,no4 #afe of the table2 hence two such1 from ,california1 exemplifying respectively the valley deposits of the ,sacramento and ,colorado rivers1 have been added to the list4 ,it must not1 however1 be understood that these typical soils necessarily represent correctly the physical constitution of all soils falling under the same popular designation2 for we are far from being able as yet to predict accurately in every case the tilling qualities of a soil material from its physical composition4 ,to do this it would be necessary not only to know with some degree of precision the several physical coefficients of each of the several grain-sizes1 and perhaps of many more intermediate ones2 but we would also have to construct a formula according to which each could be given its proper weight when present in varying proportions1 and of varying shapes1 surface condition1 and material4 ,for this our present knowledge is wholly inadequate1 if indeed the problem is not beyond the limits of mathematical computation4 ,we must for the present at least be satisfied with the empirical approximations afforded us by the constantly increasing number of such analyses1 correlated with farming experience4 ,since the finest grain-sizes above those classed as 8clay0 do not tend to 8lighten0 soils1 but even to render them more intractable 78putty soils071 while coarser ones gradually change the dense clay-texture into the 8loamy10 it is clear that in between there must be a neutral point1 some grain sizes which by themselves do not influence soil texture either way4 ,discussion of numerous physical analyses1 and some direct experiments1 have led the writer to conclude that this theoretically neutral grain-size lies at or near the diameter of 4#jbe mm41 or 4#e mm4 hydraulic value4 ,in correlating the results of analysis with the tilling qualities of the soil as to 8heaviness and lightness10 therefore1 that grain-size may usually be left out of consideration4 ,,physical ,,analyses ,,of ,,soils ,,and ,,subsoils4 7,a7 #bch ,white ,pipe ,clay4 ,tishomingo ,co4 7,z7 ,hygroscopic ,moisture 7#g to #ba;,c7 ,diameter ,velocity 7,millimeters7 7,hydr4 ,v47 ,designation of ------------------------------------- ,materials4 ,millimeters 7,a7 per sec4 ---------------------------------------- -------- ,grit #a-c 4#e-a 4#ej #fd ,sand 4#cj #cb #j4jf 4#af #af 4#ab #h #j4jh 4#jgb #d #j4jb 4#jdg #b #j4jd ,silt 4#jcf #a #j4jh 4#jbe #j4e #j4jh 4#jaf #j4be #b4jj 4#jaj #j4be #ba4ae ,clay 8 #j4jjbc #gd4fe ------- #ih4af 7,z7 #i4ji ,ferric ,oxid #j4ac ---------------------------------------- ---------- 7,b7 #bdh ,tallahoma ,subsoil4 ,jasper ,co4 7,c7 #afe ,flatwoods ,soil4 ,chickasaw ,co4 7,d7 #bjf ,pine ,hill ,soil4 ,smith ,co4 7,e7 #bji ,pine ,hill ,subsoil4 ,smith ,co4 7,f7 #cig ,oxford ,subsoil4 ,lafayette ,co4 7,g7 #bai ,table ,lands ,subsoil4 ,benton ,co4 7,h7 #agc ,prairie ,subsoil4 ,monroe ,co4 7,i7 #bcj ,h'y ,flatwoods ,soil4 ,pontotoc ,co4 7,j7 #bdf ,red ,hills ,subsoil4 ,attala ,co4 7,k7 #aif ,hog-wallow ,subsoil4 ,jasper ,co4 7,z7 ,hygroscopic ,moisture 7#g to #ba;,c7 ,,mississippi ,,uplands4 ---------------------------------------- --------------------- ,designation ,sandy4 ,loam4 ,clay4 of ---------------------------------------- -------------- ,materials4 7,b7 7,c7 7,d7 7,e7 7,f7 7,g7 7,h7 7,i7 7,j7 7,k7 ---------------------------------------- ------------------------ ,grit #f4id #b4ij #j4cf #j4cf #j4cc #j4hc #j4bcb4aj #a4ig #ag4fe #f4if #b4ih #j4hc #j4ce #a4ai #ah4ha #b4ha #f4fb #f4ba #a4dg #j4gb #a4if ,sand #aj4af #d4da #g4ge #c4chj4gi #b4ccj4fb #b4cb #a4fd #b4ff #c4ac #c4ja #c4he #a4ag #b4ji #j4hh #a4ff #b4jb #a4ei #a4di #j4ah #j4gh #j4bj #j4bc #j4gj #j4bf #a4jb #b4bc #a4ai #j4fd #j4gh #j4gf #a4bf #j4ah #a4bi #j4ai #j4hh #e4jf #c4ef #b4fc #c4ef #i4gi #b4ib #a4fa #a4hj #b4di ,silt #a4if #i4fg #f4ej #e4djac4ab #g4bf #g4cf #b4ff #c4fj #c4fg #g4hiad4ah #ac4ig #g4ggaf4fd #ac4ad #h4ha #i4ac #b4gc #e4ci #h4djbb4jc #ad4bjaf4febg4bh #ae4jg #g4hebf4fd #c4cj #aj4ca #ae4ecae4fb #bi4cfcg4geah4hg #bf4ejce4bbcb4ce #be4cc #bd4ah ,clay #h4fc #g4hf #d4ehaj4gjag4bc #ai4aicc4afbe4dh #dj4be #dg4jc ---------------------------------------- -------------- #ii4bhih4fh #ie4fgig4ggih4ce #ig4feii4ejig4hg #if4aaajj4jj 7,z7 #a4hj #c4cf #b4dh #g4fi #h4gi #g4bdaa4ce #i4cc #ah4fj #ad4dh ,ferric ,oxid #a4aj7a4de7 #a4be #d4de #b4ec #e4aa #e4db7e4ij7aj4ej #d4jj ---------------------------------------- ------------------------ 7,l7 #cij ,buckshot ,soil4 ,issaquena ,co4 7,m7 #bcg ,loess4 ,claiborne ,co4 7,n7 #cfe ,tallahatchie ,all4 ,soil4 ,panola ,co4 7,o7 #cgg ,frontland ,subsoil4 ,sunflower ,co4 7,p7 #cie ,dogw4 ,ridge ,soil4 ,coahoma ,co 7,q7 ,southwest ,pass4 ,plaquemine ,par4 7,r7 ,southwest ,mud-lump4 ,plaquemine ,par4 ,la4 7,z7 ,hygroscopic ,moisture 7#g to #ba;,c7 ,,mississippi ,,river ,,bottom4 ---------------------------------------- ------------- ,designation ,swamp4 ,river4 ,river ,deposit4 ,delta of ---------------------------------------- --------- ,materials4 7,l7 7,m7 7,n7 7,o7 7,p7 7,q7 7,r7 ---------------------------------------- ------------------- ,grit #j4ji #j4bd #j4ji #j4je #j4cg #j4jd #j4cb #j4ae #j4ah #j4aj ,sand #j4cf #j4fa #j4je #j4ic #j4ba #b4gi #j4dg #e4jb #j4ca #a4fe #a4cj #b4da #c4ge #g4jc #c4fh #j4bg #a4ie #b4fh #af4ij #ba4df #ab4ch #e4cd #a4ef #ad4be #i4ch #ai4ig #ba4hc #ac4bg #aj4ji ,silt #b4bc #af4bj #i4hh #ac4ij #ad4ja #ae4hg #e4eh #c4fh #bj4jh #bj4cg #d4bg #i4ic #h4be #i4ed #h4ig #e4ei #ai4gi #a4hi #i4eh #g4bf #h4ja #ch4ai #cc4ch #be4cj #cj4jh #h4fe #ai4fg #cd4df ,clay #dd4cj #b4ea #i4fd #e4ea #aj4ce #ab4bj #ah4ah ---------------------------------------- -------- #ajj4ja #ig4gd #ih4gc #ih4jd #ii4gb #if4eh #ajj4jj 7,z7 #ad4ca #d4ah #f4ab #e4fh #c4ie ,ferric ,oxid7#e4hb7 #c4bg #b4eh #b4ca #b4fi ---------------------------------------- ------------------- 7,s7 #aj ,sacramento4 ,sacramento ,co4 7,t7 #ejf ,gila4 ,san ,diego ,co4 7,z7 ,hygroscopic ,moisture 7#g to #ba;,c7 ,,california4 ------------------ ,designation ,river ,deposit4 of ----------------- ,materials4 7,s7 7,t7 ---------------------------- ,grit 4#ac ,sand 4#ae 4#aa 4#cb 4#ge #c4af #b4ea #aj4bg #h4cb ,silt #ac4fg #ab4fd #ac4aa #aa4bh #dc4fa #ca4gi ,clay #ab4jf #bc4ig ----------------- #if4bj #ia4ga 7,z7 #i4ah #i4bf ,ferric ,oxid ---------------------------- ,number of soil grains per gram4--,it is of some interest to consider the number of grains of different sizes that may be contained in1 e4 g41 a gram of soil4 ,if for this purpose we assume all the soil grains to be spherical1 we shall obtain the minimum figures1 for most other shapes will pack more closely4 ,king 7,physics of ,agriculture1 p4 #aag7 calculates such figures for different grain-sizes1 assuming the density to be that of quartz 7#b4fe71 with the result that while with a diameter of one millimeter 7#a-be inch7 the number of grains would be #gbj1 and with one-tenth of a mm4 #gbj1jjj2 if made of the finest particles only1 viz41 one thousandth of a mm41 the number would be #gbj1jjj billions4 ,probably few of the clayey soils we ordinarily deal with are of this order2 it is doubtless approached in certain fine plastic clays4 ,surface afforded by various grain-sizes4--,the amount of surface afforded by a similar amount of soil must naturally be considered in this connection1 since upon it depends not only the amount of moisture which the soil may hold in the form of superficial films1 but also the extent of surface upon which the weathering agencies as well as the root hairs of plants may act4 ,quoting again from ,king's work1 we find on the same premises given above for the number of grains1 that their surface would in the case of grains of one mm4 diameter be eleven square feet per pound 7about half a pint7 of material2 while in the case of the finest grade we should have #aaj1ech square feet1 or more than two and a half acres4 ,from actual experiments made with the flow of air through various soils1 ,king calculates that while in ordinary loam soils the total surface is about an acre per cubic foot1 in fine clay soils it rises to as much as four acres4 ,if we imagine this large surface to be covered with even a very thin film of water1 it is readily seen how large an amount may be present in a cubic foot of moist soil4 ,e4 ,a4 ,mitscherlich 7,bodenkunds fr ,land-und-,forstwirthe2 ,berlin1 #aije7 attributes to the surface offered by the soil particles supreme importance in determining the productiveness of soils4 ,according to him the internal soil-surface determines directly the ease with which roots can penetrate the soil2 and he proposes the determination of this factor by means of the heat produced in wetting the soil 78,benetzungswrme071 measured in a calorimeter1 as a substitute for all methods of physical soil analysis1 which are vitiated by the varying shapes and densities of the particles2 while his method gives directly the actual surface4 ,to the consumption of energy required by difficult penetration he attributes most of the differences in production1 and hence refers to the internal soil-surface as governing nearly all the other physical factors4 ,the introduction of many arbitrary assumptions1 and the failure to show that the admitted inaccuracy of the ordinary mechanical soil analyses are of any practical importance1 greatly detract from the cogency of the rigorous mathematical discussion carried through his work by ,mitscherlich4 ,influence of the several grain-sizes on soil texture4--,undoubtedly the most potent of all the sediments appearing in the above table in influencing soil texture1 is the 8clay40 ,that the materials included under this empirical designation may vary considerably in different soils1 has already been sufficiently insisted on2 and it is doubtful that in the present imperfect state of our knowledge of the functions of the several physical grain-sizes1 we would be much wiser were we to go to the extreme advocated by ,williams 7,forsch4 ,agr4 ,phys41 vol4 #ah1 p4 #bbe1 ff471 of determining with precision the actual amount of such extremely fine clay particles as cease altogether to obey the law of gravity when once suspended in water4 ,it is at least doubtful that the essential property of adhesive plasticity belongs only to these1 for this property doubtless increases gradually as the size diminishes1 although unquestionably not a mere function of the latter1 since it belongs only to the hydrated silicate of alumina4 ,ferric ,hydrate4--,probably the body which most commonly modifies materially the adhesive and contractile properties of the clay substance1 is ferric hydrate2 the more as on account of its high density it tends to exaggerate materially1 in many cases1 the apparent content of true clay1 and the estimate of the soil's plasticity based upon it4 ,a good example in point is the case of soil ,no4 #bdf 7,miss47 of the above table4 ,this is a heavy clay soil1 yet not excessively adhesive2 scarcely as much so as ,no4 #bcj 7,miss471 the heavy gray 8flatwoods0 soil1 and not nearly as 8sticky0 when wet as ,no4 #agc 7,miss471 the prairie subsoil1 although containing apparently #ae more clay than the former1 and #g more than the latter4 ,but ,no4 #bdf is a highly ferruginous clay1 in which the ferric hydrate is in a very finely divided condition1 and materially influences the physical qualities of the clay substance4 ,were it all accumulated in the 8clay10 it would diminish the percentage of true clay by #aa4ge1 reducing the clay-percentage to #bh4e which accords more nearly with the soil's only moderate adhesiveness1 and not excessively heavy tillage4 ,but it must be remembered that the iron oxid shown in the analysis is not nearly always in this finely diffused condition4 ,frequently it incrusts the sand grains2 quite commonly it forms small concretions of limonite1 which themselves act as sand grains2 and again1 it may be present in the form of 8black sand0 or magnetic oxid1 as is commonly the case in ,california and on the ,pacific slope generally4 ,to take this point properly into account1 therefore1 it would be necessary to determine the amount of ferric hydrate actually present in the 8clay0 as separated by subsidence of the granular constituents4 ,other substances4--,this circumstance as well as the inevitable presence of other modifying substances1 clearly shows the desirability of being enabled to examine the physical properties of this 8clay0 directly1 by collecting its entire amount as obtained in analysis1 instead of merely determining it by weighing fractional portions4 ,when this is done the analysis is much more valuable as indicating the true tilling qualities of the land4 ,the increase of bulk suffered by this substance after wetting1 is a very fair index of its content of true clay1 and is preferable to the chemical analysis proposed by some investigators4 ,for it is quite impossible to distinguish the silica and alumina derived from the kaolinitic substance proper1 from that which is due to the decomposition of zeolites4 ,it is possible1 however1 to determine the possible maximum of the kaolinite ingredient by taking into consideration the quantitative ratio according to which silica and alumina combine to form it1 viz41 approximately #df of the former to #dj of the latter1 the rest being water4 ,by using this calculation we can often demonstrate clearly the presence in the 8clay0 of considerable amounts 7up to #cc7 of aluminic hydrate2 since no zeolitic mass can contain as much alumina as does kaolinite4 ,whether the aluminic hydrate be in the form of gibbsite1 bauxite1 diaspore1#bg or in the gelatinous state1 the nature of the soils containing it proves that it is totally destitute of plasticity and adhesiveness2 and this consideration will often serve to explain the fact that soils showing in their chemical analysis high percentages of alumina1 nevertheless show quite low degrees of plasticity1 adhesiveness and water absorption4 ,what part it may take in modifying the physical properties of the soil we can thus far only conjecture4 #bg ,bauxite is not only the most abundant of the three hydrates of alumina known to occur naturally1 but also stands nearly midway between the two others in its water content1 viz41 a little over #be2 that of diaspore being nearly #ae1 gibbsite about #ce4 ,influence of the granular sediments upon the tilling qualities of ,soils4--,considering the granular sediments by themselves1 in the absence of clay1 it may be stated in a general way that while in a moist condition they flocculate sufficiently to produce a fair tilth1 they will nevertheless on drying collapse into a close arrangement resulting from the single-grain structure4 ,the form of the grains being angular instead of rounded1 they are apt to form a very closely packed mass far from suitable to vegetable growth2 as will be seen by an example taken from one of the culture stations of the ,university of ,california1 from a piece of land which on the surface would be called a very sandy loam1 but after we descend increases in its content of fine grains until at a depth varying from eighteen inches to three feet we find what appears to be a hardpan1 which is equally impervious to roots and water and causes the water to stagnate to such an extent that after heavy rains the land becomes so boggy as to render plowing almost impossible without endangering the team4 ,a close examination of this hardpan shows that1 unlike others1 it is devoid of any cement1 and when taken out can be readily crushed between the fingers1 and softens in water1 but does not become plastic4 ,its imperviousness is therefore due solely to the close packing of the sand grains1 for it contains practically no plastic clay1 and under the microscope the grains are seen to be angular-wedge-shaped and composed of the remnants of granite4 ,the physical analysis shows the following result3 ,,mechanical ,,analysis ,,of ,,hardpan4 ,designation4,diameter4,percentage4 -------------------------------- 4#ej mm4 #aj4ic ,sand 4#cj 8 #ba4bc 4#ab 8 #g4bg 4#jgb 8 #i4fc 4#jdg 8 #ab4jj ,silt 4#jcf 8 #g4ai 4#jbe 8 #a4be 4#jaf 8 #ad4bj 8,clay0 8 #h4fd -------------------------------- ,it is doubtful whether this condition of things can be remedied by the usual measure of breaking up the hardpan either by hand or by means of giant-powder blasting4 ,experience seems to show that the effect is only temporary1 and that in the course of time1 by the action of the percolating waters1 the particles settle back into their original impervious condition4 ,it is just possible1 however1 that if once penetrated by roots1 the intervention of these would permanently destroy the close structure1 so as to make this a fair subsoil for the growth of trees and other plants4 ,the writer is not aware that this kind of purely physical hardpan without cement has ever been observed elsewhere4 ,this physical condition is doubtless responsible for two other phenomena1 viz41 the 8putty soils10 and also certain difficulties experienced in irrigation4 8,putty ,soils0 is the name popularly given in the ,cotton ,states1 and probably elsewhere1 to soils usually occurring in low ground and also known as 8cray-fishy40 ,they consist of very uniform1 powdery sediment1 with little or no coarse sand and still less of clay to render them coherent4 ,when wet these soils behave precisely as would glazier's putty1 adhering to the surface of even the best-polished plowshare1 so that no furrow-slice can be turned and the plow is soon dragged out of the ground4 ,at a very closely limited condition of moisture such lands may plow fairly well2 but when this limit is passed in the least 7as sometimes happens in the course of a single day71 it turns up only hard clods1 which in a few hours of sunshine become so hard that no instrument of tillage short of a sledgehammer will make any impression upon them4 ,the physical analysis of these usually gray soils shows that they contain only a trifling amount of clay2 perhaps #a or #b1 playing the part of linseed oil in making putty out of whiting4 ,even the addition of lime does not help such soils much1 because there is little or no clay to flocculate4 ,they are1 as a matter of fact1 among the most refractory lands the farmer has to deal with4 ,a soil showing similar behavior1 though not quite as extreme as in the case of the ,gulf or ,cotton ,states' soils in question1 occurs at the culture substation at ,paso ,robles1 ,california1 and is probably closely correlated to the physical hardpan referred to above4 ,the physical analysis of this soil yielded the following result3 ,,mechanical ,,analysis ,,of ,,soil4 ,designation4,diameter4,percentage4 -------------------------------- 4#ej mm4 #ad4bd 4#cj 8 #ae4ag ,sand 4#af 8 #h4hh 4#ab 8 #e4fj 4#jgb 8 #f4ge 4#jdg 8 #h4ce ,silt 4#jcf 8 #h4ee 4#jbe 8 #f4jc 4#jaf 8 #ag4gg 8,clay0 8 #g4ej -------------------------------- ,it would seem the best and almost only remedy to be applied to such soils as these is the introduction of vegetable matter or green-manuring1 by which their texture is loosened3 for the hauling of mere clay upon the land would hardly accomplish the purpose intended1 within the limits of farm economy4 ,dust ,soils1 which during the dry season are even in their natural condition so loose as to rise in clouds and render travel very uncomfortable1 are not uncommon in arid countries1 e4 g41 in ,washington and adjacent parts of ,oregon1 on the uplands bordering the ,columbia1 ,yakima and ,snake rivers4 ,the physical analyses of three of such soils1 given in the table below1 will convey some idea of their peculiarities in this respect4 ,,physical ,,analysis ,,of ,,dust ,,soils4 ,hydr4 ,value4,diameter4 ,no #ag4,no4 #cg4,no4 #gi4 ---------------------------------------- ------------ ,clay 4#jjbc4 mm4 4#aj--8 4#ic #c4ei #a4bg 4#be mm4 4#jaj #cj4ic #ac4jf #cb4bi ,silt 4#be to 4#e 4#jaf #c4bj #e4hb #ab4ge 4#e to #b4j 4#jbe-4jdg #g4ah #bg4cg #cg4ea #b4j to #h4j 4#jdg-4abj #ba4hh #dc4gh #aj4ib ,sand #h4j to #fd4j 4#ab- 4#ej #cb4ci #di4eg #c4ig -------------------- ,total #if4eg #ih4ah #ih4gb ---------------------------------------- ------------ ,slow penetration of ,water4--,soils of this class are wetted with extreme slowness by irrigation water2 so that when first taken under cultivation it sometimes takes twenty-four hours to soak the land for twelve inches in each direction4 ,irrigation furrows must be placed very close together and in large numbers1 in order to ensure the wetting of the soil so that the crop shall not suffer from lack of moisture at a distance of two or not more than three feet4 ,where the irrigation furrows are drawn farther apart a fine stand of grain may be seen within eighteen inches of the same1 while farther away the crops may be dying from lack of moisture4 ,this difficulty is by no means infrequent in the arid region1 and is difficult to overcome except by frequent and thorough tillage1 which gradually increases the rapidity of water-penetration2 as has been shown in the soils of the alluvial prairies of the ,yakima country in the ,state of ,washington4 ,it is necessary1 however1 to take care that they shall always contain an adequate amount of humus or vegetable matter1 in order to prevent re-consolidation by the burning-out of the humus during the warm1 rainless season4 ,there is an unmistakable resemblance between these dust soils of the ,northwest and the 8putty0 soils mentioned above2 both showing a very low percentage of clay with a relatively large amount of the finest sediments1 with a sudden downward break of the curve before the coarser grain-sizes are reached4 ,it would seem as though the absence of these intermediate grains favors the close packing of the fine sediments in the interstices of the coarse ones1 thus bringing about the imperviousness1 which is the chief obstacle to their cultivation4 ,effects of coarse ,sand4--,coarse sand intermingled with heavy clay soils has but little effect in improving the tilling qualities1 unless carried to such excess as renders it financiallyimpracticable4 ,in actual practice it is frequently possible to improve such soils by properly distributing upon them the washings of the adjacent hills1 which will always carry sands of many grades2 and when it is intended to improve garden land by hauling sand it is important to choose the latter so as to complement the deficient grain-sizes of the soil4 ,the sand of wind drifts or dunes is generally well adapted to such improvement1 being1 as ,udden#bh has shown1 of a fairly definite composition of sufficiently wide range of grain-sizes for the purpose4 ,the effects of humus in modifying soil texture are discussed farther on4 #bh ,the ,mechanical ,composition of ,wind ,deposits1 ,bull4 ,no4 #a1 ,augustana ,library ,publications2 #ahih4 ,,chapter ,,vii4 ,,the ,,density ,,and ,,volume-,,weight ,,of ,,soils4 ,aside from the humus-substances the specific gravity of the common soil constituents1 taken individually1 do not vary widely2 kaolinite being the lightest 7#b4fj71 feldspar next 7#b4fb72 then quartz 7#b4fe71 calcite 7#b4gb74 ,mica and hornblende range 7according to their iron contents7 from #b4gb to over #c4j4 ,the average specific gravity of soils of ordinary humus content only will thus range between #b4ee and #b4ge2 sandy soils approaching very closely to that of quartz alone4 ,volume-,weight4--,the specific gravity of the soil is1 however1 of little practical consequence compared with the 8volume-weight10 i4 e41 the weight of the natural soil as compared with an equal bulk of water4 ,a cubic foot of water weighs #fb pounds2 a similar volume of soil usually weighs more1 but in the case of peaty lands may actually 7when dry7 weigh less4 ,the extreme range is from #aaj pounds for calcareous1 and somewhat less for siliceous sand1 to as little as #cj to #ej pounds in the case of peaty and swamp soils4 ,it may be conveniently remembered that while average arable loams range from #hj to about #ie pounds per cubic foot1 8heavy0 clay soils range from #ge pounds down to #fi1 observed by the writer in the case of certain alluvial soils1 poor in humus1#bi of the ,sacramento river1 ,california4 ,manured garden soils1 and the mold surface soil of deciduous forests1 generally contain so much humus as to depress their weight considerably1 varying according to their state of tilth from #ff to #gj pounds per cubic foot4 #bi ,this remarkable soil seems to have been derived from the finest 8slickens0 of the hydraulic gold mines4 ,weight per acre-foot4--,as for practical purposes and calculations it is often desirable to know approximately the weight in pounds of an acre 7#dc1efj square feet7 one foot deep1 it is convenient to remember that in the case of sandy land1 this weight 7per 8acre-foot07 may be assumed at four millions of pounds2 for loams1 at #c millions2 for clay lands1 #c millions2 for humus or garden land and woods earth1 about #c millions of pounds2 for reedy swamp and peaty lands1 #b to #b millions4 ,the loose tilth and humus-content of the surface soil will in general cause it to weigh less1 bulk for bulk1 than the underlying subsoil1 even when the latter is more clayey2 moreover1 the continuous pressure from above will tend to consolidate the subsoil and substrata4 ,warington 7,phys4 ,properties of ,soils1 pp4 #df1 #dg7 gives interesting data on this point from the ,rothamstead fields1 as follows3 ,old pasture1 first nine inches #ga4c pounds per cub4 ft4 ,same1 fourth 8 8 #ajb4c 8 8 8 8 ,arable land1 first 8 8 #hi4d 8 8 8 8 ,same1 fourth 8 8 #aja4d 8 8 8 8 ,the influence of humus and unhumified organic matter1 as well as of tillage1 in diminishing the volume-weight of soils is here strikingly shown4 ,air-space in ,natural ,soils4--,the difference between the specific gravity as usually determined1 and the volume-weight of soils1 is of course caused by the large amount of air contained in them when dry1 but which in wetting them is partially or wholly replaced by water4 ,illustration3 ,,fig4 #aj4--,various possible arrangements of soil particles4 ,theoretically1 assuming all soil grains to be globular1 and packed as closely as possible 7in oblique order71 the space not filled by them would be the same for all sizes1 whether that of marbles1 or so minute as to be hardly felt between the fingers2 and would be #be4ie per cent of the soil volume4#cj ,if the same globular particles were packed as loosely as possible1 i4 e41 in square instead of oblique order 7see figures #aj and #aa71 the vacant space would be #dg4fd per cent ,if however we imagine each sphere to be itself composed of a number of smaller ones1 the empty space will obviously be greatly increased1 to an extent proportionate to the diminution of solid mass thus brought about4 ,the pore-space might in that case1 with the oblique arrangement of the globules as shown in ,fig4 #aj1 be as high as #gd4je per cent ,but since the soil particles may be of all shapes and sizes within the same soil1 and usually fit much more closely than would globular grains1 the empty space rarely approaches 7only in certain alluvial soils and in loose mulches7 to the figure last named4 ,in sandy soils it may fall as low as #bj1 and in coarse gravelly soils even as low as #aj4 ,most cultivated soils range between #ce and #ej of empty space4 #cj ,king1 ,physics of ,agriculture1 p4 #aaf1 ff4 ,effects of ,tillage4--,that these figures can be only approximations is obvious from the consideration that one and the same soil will vary materially in its volume-weight according to its temporary condition of greater or less compactness4 ,after land has been beaten by winter rains1 its volume-weight will be found to have materially increased from the well-tilled condition brought about by thorough cultivation4 ,this difference is strikingly seen when1 in plowing1 the height of the ground on the land side is compared with that of the turned furrow-slice in well conditioned loamy land4 ,this loose condition is called tilth1 and it results from the formation of relatively large1 complex crumbs#ca or floccules1 between which there are large air spaces that were wholly absent in the untilled land2 the floccules themselves being also more loosely aggregated than was the case before tillage4 #ca ,the word crumbs1 which is generally understood as meaning a relatively large1 loose aggregate1 seems preferable to the word kernels1 suggested for the same by ,king 7,physics of the ,soil1 p4 #aaj74 ,kernels are understood to be bodies rather more solid than the surrounding mass1 and do not convey the idea of loose aggregates4 ,the word 8,krmelstructur0 7crumb-structure71 adopted by ,wollny for this phenomenon1 has both fitness and priority in its favor4 ,illustration3 ,,fig4 #aa4--,land before and after plowing4 ,the compactness of the soil is indicated by the density of dotting4 ,before plowing there is a compact surface crust 7s71 below which the soil becomes less and less compact as we go deeper4 ,after plowing we find the soil 7fs1 furrow-slice7 converted into a loose mass of crumbs 7floccules71 with increase of bulk4 ,compacted plowsole at pl4 ,illustration3 ,,fig4 #ab4--;,a soil-crumb1 magnified to show the particles of which it is composed4 ,the particles are held together by the water-menisci1 just as are the hairs of a brush when wetted4 ,the white spaces between the particles represent air4 ,crumb or ,flocculated structure4--,figure #aa illustrates the difference between the unplowed land1 consolidated especially on the surface by winter rains1 and in its upper portion consisting largely of single grains2 while the plowed land1 toward which the furrow-slices have been turned1 is greatly increased in height and volume and consists almost wholly of variously-shaped and-sized aggregates or floccules1 loosely piled upon one another and separated by large interspaces4 ,the increase in volume from consolidated clay to crumb-structure is given by ,wollny 7,forsch41 vol4 #bj1 p4 #ac1 #ahig7 at #da4i1 to powder as #cc4 ,on moistening dry clay increased #cf4i1 quartz powder #h4ja4 ,when land is plowed in the proper moisture-condition the crumbs of floccules are held together by the surface tension of the capillary films 7menisci7 of water at the points of contact4 ,in the case of sands1 the crumbs will collapse into single grains whenever the water-films evaporate1 unless some cementing substance was dissolved or suspended in the water4 7,see figure #ab74 ,lime carbonate is one of the substances most commonly found permanently cementing the floccules2 hence the ready tillage of most calcareous soils1 and especially the loose texture of the 8loess0 of the western ,united ,states1 and of ,europe and ,asia4 ,in these deposits we find sandy and silt aggregates or concretions ranging from ten or more inches in length 7loess puppets7 to microscopic size1 held together by lime carbonate1 but collapsing into silt and sand when the material is treated with acid so as to dissolve the cement4 ,the rough surfaces of these aggregates1 gripping into each other1 explain the stability of the steep loess cliffs in the ,united ,states1 as well as in northeastern ,china1 as observed by ,von ,richthofen and ,pumpelly4 ,clay is most frequently the substance which imparts at least temporary stability to the crumbs and crumb-structure2 this is one of its most important functions in soils1 as it serves to maintain tilth once imparted by cultivation1 even after the land dries out4 ,beating rains1 and cultivation while too wet1 will in this case of course destroy the crumbs and the loose tilth4 ,other substances which greatly aid the maintenance of tilth are the several humates 7of lime1 magnesia1 iron71 which when fresh are colloidal 7jelly-like7 like clay itself1 but unlike the latter1 when once dried do not resume their plastic form by wetting 7,schloesing74 ,the crumbs thus formed are therefore quite permanent and contribute to the looseness of soils rich in humus4 ,one part of lime humate is said by ,schloesing to be equal in cementing power to eleven parts of clay4 ,silica1 silicates and ferric hydrate are sometimes found cementing soil crumbs1 wholly or in part4 ,the importance of the ready penetration of air1 water and roots thus rendered possible is obvious2 and the question arises how it happens that wild plants are able to do without tillage4 ,how ,nature ,tills4--,when we examine the undisturbed soil of woods or prairie in the humid region1 we will as a rule find the natural surface soil in a very good condition of tilth2 the obvious cause being the presence in it of an abundant network of surface roots and rootlets of grasses and herbs1 which in connection with the fallen foliage prevent the beating and compacting of the soil surface2 which can be seen to happen before the observer's eyes whenever a heavy rain falls on a bare land surface1 however well tilled4 ,crusting of ,soils4--,in some soils1 especially of the ,gulf ,states1 the beating of rain followed by warm sunshine so effectually compacts the surface that in the case of taprooted plants like cotton1 it becomes necessary to cultivate after each rain1 so as to break the crust that would otherwise not only prevent the proper circulation of air1 but would also serve to waste the moisture of the land4 ,the same land in the wild condition suffered no such change1 being protected by the native vegetation1 and by fallen leaves4 7,see chapt4 #h74 ,soils of the arid region4--,in the regions of deficient rainfall the conditions are modified in several respects4 ,grass sward rarely exists1 nearly all grasses assuming the habit of growing in tufts or bunches some distance 7a foot or two7 apart2 hence the name of 8bunch grass0 commonly used1 which however means not any one definite kind of grass1 but serves to distinguish the grasses of the uplands from those of the moist lowlands1 where true sward may be found4 ,between these bunches of grass the soil is fully exposed1 and being free from roots and leaf-covering is compacted1 unless its nature is such that the usually gentle rains do not produce a serious crusting of the surface4 ,that such is actually the predominant nature of the soils formed under arid influences has already been stated2 and thus the hard-baked soil-surface so often seen in the ,eastern ,united ,states in unplowed bare land1 or during the prevalence of a drought1 is rarely seen in the arid region4 ,the clay lands that do exist are usually sufficiently calcareous to possess the property of 8slaking0 into crumbs whenever wetted after drying4 ,but where this is not the case1 the stony hardness brought about by the long dry and warm season is long in being removed by the winter rains4 ,changes of soil-volume on wetting and drying4--,the behavior of colloidal clay in the above respects has already been described above 7see chapt4 #d1 page #ei74 ,it is obvious that whenever soils contain a large proportion of such clay1 their behavior on wetting and drying will approximate to those of the pure clay4 ,this is exemplified in the heavy clay1 or so-called 8prairie soils0 of the ,united ,states1 which when thoroughly wetted in spring will1 during a dry summer1 form wide1 gaping cracks4 ,these in the long summers of the arid region may extend to the depth of several feet1 with a width of as much as three and more inches at the surface of the ground4 ,this1 of course1 contributes greatly to the drying-out of the soil to the same depth1 and results as well in the mechanical tearing of the root-system of growing plants2 sometimes causing the total destruction of vegetation4 ,in some clay soils it happens that after a rain or irrigation1 the shrinkage occurring upon the advent of warm sunshine will cause the surface crust to so contract around the stem1 e4 g41 of grain1 as to constrict and injure the bark1 causing serious injury to the crop4 ,in soils of this character very thorough tillage in preparing for a crop1 and the maintenance of a loose surface during its growth1 are of course extremely essential4 ,in the arid region it will frequently happen that such soils when not tilled to a sufficient depth1 will during the later part of the summer so shrink and crack beneath the shallow-tilled surface layer that the latter will bodily fall into the cracks1 exposing the roots to all the deleterious influences of mechanical lesion and drying-out4 ,it is thus obvious that the cultivation of such soils should not be undertaken at all by those not naturally able and willing to bestow upon them1 to the fullest extent1 the deep and thorough tillage which is absolutely essential in the utilization of their usually high productive power4 ,extent of ,shrinkage4--,the extent of this shrinkage in drying1 and subsequent expansion in wetting1 have been measured by the writer by the use of the sieve cylinder described below 7chapt4 #aa1 p4 #bji71 as serving for the determination of the water capacity of soils4 ,when a soil of the kind above referred to is placed in the sieve cylinder in the tilled 7flocculated7 condition1 then allowed to absorb its maximum of water and then dried at #ajj degrees ,c41 the contraction in drying can be very strikingly seen1 and its amount measured by filling up the empty space with mercury2 then measuring the latter after expelling the surplus by means of a ground glass plate laid on top4 ,the contraction of several heavy clay soils1 thus measured1 has been found by the writer to range from #bh to as much as #dj per cent of the original bulk4#cb ,the soil thus contracted1 when again wetted1 does not return altogether to its original bulk1 but remains in a more or less compacted condition1 like that of a soil which has been rained upon4 #cb ,wollny 7,forsch4 ,vol4 #bj1 p4 #ac ff41 #ahig7 records similarly high shrinkages in his experiments4 ,the expansion and contraction of a heavy clay soil on wetting and drying are well illustrated in the figure below1 in which the soils are shown in the shallow cylinder which serves for the determination of water-holding power 7see chapt4 #aa1 p4 #bji74 ,the middle figure shows in profile the expansion of a dry1 pulverized 8black adobe10 struck level1 when allowed to absorb its maximum of water2 it rises above the rim of the sieve-box to nearly the half height of the latter4 ,the outside figure to the right shows the same soil after drying2 that to the left1 a red clay soil similarly treated4 ,it is easily seen that these variations in volume may bring about very marked results in the fields2 the surface of which1 apart from the cracks usually formed1 may be several inches lower in the dry season than during wet weather4 ,illustration3 ,,red ,,clay ,,soil4 ,,black 8,,adobe0 ,,clay ,,soil4 ,,fig4 #ac4--;,expansion on ,wetting and ,contraction on ,drying of heavy clay soils4 ,contraction on ,wetting4--,in the case of alkali soils containing much carbonate of soda1 a very notable contraction occurs in wetting the loose1 dry soil4 ,the cause is here obviously the collapse of the crumbs1 formed in dry tillage or crushing1 into single grains1 closely packed4 ,the same result is observed in the naturally depressed 8alkali spots0 7see chapt4 #bb74 8,hog-wallows40--,in the field the wetting of cracked clay soils produces some very curious effects4 ,the effect of the first light rains usually is to crumble off the edges or angles near the surface1 the materials thus loosened falling into the lower portion of the cracks4 ,this is repeated at each successive shower followed by sunshine1 the crevices thus becoming partly filled with surface soil4 ,when1 subsequently1 the heavier and more continuous rains wet the land fully1 also causing the consolidated mass in the crevices to expand1 the latter cannot close on account of the surplus material having fallen into them2 the result being that the intermediate portions of the soil are compelled to bulge upward1 sometimes for six or more inches1 creating a very uneven1 humpy surface1 well-known in the southwestern ,united ,states as 8hog-wallows40#cc #cc ,a totally different kind of 8hog-wallows10 occurring in ,california and the arid region generally1 have been described in a previous chapter under the head of ,aeolian soils 7,see chapt4 #a1 p4 #i74 ,such a surface is always therefore an indication of an extremely heavy soil1 difficult to cultivate2 yet embracing some of the most highly and permanently productive lands known in the ,united ,states1 and in ,india1 where the 8regur0 lands of the ,deccan are of this character2 they have been cultivated without fertilization for thousands of years4 ,the subjoined physical analyses of lands of such extreme character as to be almost uncultivatable will serve to exemplify their physical composition4 ,,physical ,,analyses ,,of ,,heaviest ,,clay ,,soils4 ,no #bdb ,miss4,no4 #fdc ,cal4 ------------------------ ,hog-wallows ,black ,adobe4 soil4 ,contra ,costa ,jasper ,co4 ,co4 ,mississippi4,california4 ---------------------------------------- ------------------------- ,weight of gravel over #a4b mm4 diameter 4#hc 8 8 between #a4b and #a mm 8 8 between #a and #j4f mm #a4ai ,fine earth #ig4ih #ajj4jj ------------------------ #ajj4jj #ajj4jj ,,fine ,,earth4 ,hydr4 ,value4 ,diameter4 ---------------------------------------- ,clay 4#jjbc mm 8 #dh4jj #de4if #j4be mm 4#jaj #ce4ah #cg4fd #j4be mm 4#jaf ,silt #j4e mm 4#jbe #e4ej #b4gd #a4j mm 4#jcf #c4gd #c4ca #b4j mm 4#jdg #b4ed #b4ie #d4j mm 4#jgb 4#bj #b4ci #h4j mm 4#abj 4#bg #a4fh #af4j mm 4#afj 4#ij 4#gi ,sand #cb4j mm 4#cj #a4fg #b4cf #fd4j mm 4#ej #b4jj ------------------------ #ajj4jj #ajj4jj ---------------------------------------- ------------------------ ,it will be noted that in both these extremely heavy soils the sum of the clay and finest sediments is a little over #hc4 ,it should be stated that both these soils after being thoroughly wetted become so adhesive that it is almost impossible to travel over the tracts occupied by them1 and that they are practically almost untillable1 being too adhesive when wet2 yet if allowed to dry to a certain extent 7varying within very narrow limits7 they turn up by the plow in large clods1 which after a few hours of sunshine become of stony hardness and will resist all efforts at pulverization or the production of tilth4#cd #cd ,in driving a light carriage over the land represented by ,no4 #fdc above1 after a light rain1 the wheels gathered up so much soil within a hundred yards as to render it necessary to stop and chop it off the tires by means of a hatchet4 ,this is a common experience in the black prairie lands of ,texas4 ,calcareous ,clay ,soils crumble on drying4--,the heavy clay soils of some of the calcareous prairies of the ,southwest1 instead of contracting into a stony mass on drying1 on the contrary resolve into a mass of crumbs1 thus producing excellent tilth4 ,this occurs even though the land may have been plowed when wet1 and of course is a great advantage4 ,the most striking exemplification of this peculiarity occurs in the heavy but profusely fertile 8buckshot0 clay lands of the ,yazoo bottom1 in ,mississippi1 where it is usual to plant corn and sweet potatoes in the semi-fluid mud left after an overflow1 after turning a shallow furrow1 then covering by turning another4 ,to the onlooker it seems impossible that such plantings could be successful2 but within a short time the muddy surface becomes a bed of crumbs 78buckshot071 forming a seed-bed not readily excelled by any made by artificial means4 ,hence1 largely1 the almost invariable success of crops in the ,yazoo region4 ,port ,hudson ,bluff4--,the same clay produces a most unpleasant result at the foot of the ,port ,hudson bluff1 where it crops out some feet above low water4 ,when after a freshet the water level falls below this stratum1 on drying the clay disintegrates into crumbs just as does the ,yazoo buckshot soil2 with the result that at the next rise1 the loose mass subsides into the river as a flood of mud4 ,thus the foot of the bluff is being constantly undermined1 and the falling of the bluff scarp has obliged the town above to recede many hundreds of feet from its original historic site4 ,the exact proportions of lime carbonate necessary to produce this phenomenon1 and its necessary relations to clay substance and other physical soil ingredients1 yet remain to be investigated4#ce #ce ,schbler 7,grundstzed4 ,agrikulturchemie1 #ahch7 ascribes the crumbling of calcareous clay soils to the difference in the contraction of calcareous sand and the clay substance4 ,but it is doubtless more directly connected with the flocculation of the latter by lime4 ,loamy and ,sandy ,soils4--,it is largely the absence of these extreme changes of volume that renders the cultivation of loamy or even sandy lands so much more easy1 and the success of crops so much more safe1 than is the case in clay soils4 ,whenever the content of colloidal clay diminishes below #ae1 the shrinkage in drying from the wet condition becomes so slight as to cause no inconvenience2 while in sandy soils properly speaking1 no perceptible change in volume occurs4 ,peaty soils1 however1 and all those containing a relatively large amount of humus1 are also liable to visible shrinkage when passing from the wet to the dry condition4 ,but on account of their looseness and porosity such shrinkage does not usually result in the formation of cracks or rupture of the roots1 as is the case in heavy clay lands4 ,the entire mass of the soil then shrinks downwards1 but rarely forms cracks on the surface4 ,hence the introduction of humus into 8heavy0 soils is among the best means of improving their tilling qualities4 ,formation of ,surface ,crusts4--,some soils1 especially those of a clay-loam character1 are very liable to the formation of hard surface crusts from the beating of rains1 and from surface irrigation2 owing1 doubtless1 to the ready deflocculation of their clay substance4 ,it is not easy to define the precise physical composition conducive to this crust formation2 but the subjoined physical analyses show examples of soils in which this tendency is very prominent and is frequently annoying1 in that when they occur in the regions of frequent summer rains1 it becomes necessary after each one to till the surface in hoed crops 7e4 g41 in cotton-fields7 in order to prevent the injurious effects of such consolidation of the surface4 ,it may1 of course1 be prevented by mulching1 or on the large scale by green-manuring1 to such extent as to prevent contraction4 ,the subjoined physical analyses of two soils from the ,brown-,loam region of ,northern ,mississippi 7see chap4 #bd71 shows the composition of lands excellent in every respect other than the tendency to crust after each rain3 ,,physical ,,analyses ,,of ,,crust-,,forming ,,soils4 ,diameter4,hydr4 ,value4,no4 #bai4,no4 #aig4 ---------------------------------------- --------------- ,coarse materials #a-c mm4 4#bc 4#e-a 8 4#ej #fd mm4 #a4dg ,sand 4#cj #cb 8 #b4cc 4#gi 4#af #af 8 #a4ag 4#ab #h 8 4#gh 4#ah 4#jgb #d 8 4#gf 4#gh 4#jdg #b 8 #i4gi #c4ef ,silt 4#jcf #a 8 #g4bj #ac4ab 4#jbe 4#ej #ac4aa #af4fd 4#jaf 4#be #ae4jg #bg4bh 4#jaj 4#be #bf4cf #ah4hg ,clay 8 4#jjbc #ai4aj #ag4bc ---------------------------------------- --------------- ,these soils agree in having a sufficient amount of clay 7#ag to #ai7 to characterize them as clayey loams1 associated with a very large proportion of the grain-sizes of less than 4#jbe mm41 or 4#e mm4 hydraulic value4 ,a higher proportion of clay1 even though associated with a similarly high or even larger proportion of these fine sediments1 seems to prevent crusting1 probably because the swelling of the clayey ingredient on wetting and its extravagant contraction in drying breaks up the continuity of the surface4 ,the heaviest clay soils1 such as those shown on a preceding page1 neither crust nor crumble on drying after wetting1 but contract into lumps of stony hardness1 as a whole4 ,the burning-out of the humus from well-tilled surface soils during the extended heat and dryness of rainless summers1 brings about such a contraction or packing of the surface soil of orchards in ,california as to greatly reduce their productiveness1 and to render necessary diligent green-manuring as the only practical remedy4 ,in many cases1 liming of the surface also serves well to prevent this injurious effect1 which to some extent of course follows surface irrigation as well as rains4 ,in most soils1 repeated alternate wetting and drying in place produces a loose1 flocculated texture1 so long as no deflocculation is brought about by mechanical causes1 such as beating rains or running water4 ,effects of ,frost on the ,soil4--,the expansion suffered by water in freezing necessarily tends to separate the soil particles previously held together by the surface tension of the capillary water1 or otherwise flocculated or cemented4 ,freezing of the soil is therefore of material assistance in disintegrating cloddy1 ill-conditioned soils1 leaving them in loose1 crumbly condition after the ice has melted and the surplus water drained off2 so as to materially facilitate tillage and root penetration4 ,when1 however1 soils thus circumstanced are tilled or trodden while too wet1 they quickly become puddled1 being practically reduced to single-grain structure4 7,see this chapt4 p4 #aaj74 ,hence the injury caused by allowing cattle to range in winter on cultivated land subject to freezing and thawing1 which it sometimes takes years to correct4 ,a disagreeable effect often produced by the freezing and thawing of wet lands is the 8heaving-cut0 of grain1 resulting from the upward expansion of the surface soil in freezing1 that may readily rupture the roots2 while on thawing1 the soil surrounding the upheaved stool is apt to settle down1 especially in case of a rain1 leaving the stool and roots exposed either to drying or freezing1 as the case may be4 ,hence the desire of grain farmers in northern climates1 for a sufficient covering of snow to protect the fall-sown grain1 rather than an 8open winter10 during which the grain is exposed to alternate freezes and thaws1 or extreme cold4 ,in certain soils1 notably in those liable to crusting 7p4 #aag71 instead of heaving the soil1 the water in freezing emerges bodily from small cracks1 in foliated or wire-like forms 78ice-flowers07 resembling those of native silver1 and formed substantially in the same way1 by a kind of 8wire-drawing0 process1 aided by crystallization4 ,small ice-crystals formed on the surface of small crevices filled with water cause others to be formed at their lower ends1 and the expansion occurring in freezing1 forces the ice upward2 the process repeating itself under favorable conditions1 until the stalks or sheets of ribbed ice grow to a height of several inches4 ,this phenomenon is especially frequent in the middle cotton ,states--,arkansas1 ,tennessee1 northern ,mississippi1 etc41 where frequent changes from rainstorms or thaws to cold northwest winds occur in winter4 ,,chapter ,,viii4 ,,soil ,,and ,,subsoil4 ,,causes ,,and ,,process ,,of ,,differentiation4 ,,humus4 ,soil and ,subsoil ,ill-defined4--,while the general mass of rock debris formed by the action of the agencies heretofore discussed as soil-material1 may under proper conditions become soil capable of supporting useful plant growth1 universal experience has long ago recognized and established the distinction between soil and subsoil3 by which are ordinarily meant1 respectively1 the portion of the soil-material usually subjected to tillage1 and what lies beneath4 ,there can be no question about the practical importance of this distinction2 but the definition of the two terms1 as commonly given in some works of agriculture1 is both incomplete and1 in its application to many cases1 partly misleading4 ,the differentiation of soil and subsoil is due partly to the action of organic matter and micro-organisms1 partly to physico-chemical causes1 now to be discussed in detail4 ,,the ,,organic ,,and ,,organized ,,constituents ,,of ,,soils4 ,humus in the ,surface soil4--,the most obvious mark of distinction between soil and subsoil is1 usually1 the darker tint of the former1 due to the presence of humus or vegetable mold1 which becomes most apparent by darkening of the tint when the soil is moistened4 ,thus soils having a gray tint when dry1 may become almost black when wetted4 ,when no such deepening of color occurs in wetting1 the absence or great deficiency of humus may safely be inferred4 ,the only other substance whose presence may invalidate the conclusions based upon the darkening of the soil tint1 is ferric hydrate 7iron rust71 which itself possesses the property of darkening on wetting1 and may effectually cover either the presence or the absence of humus4 ,since the formation of the humus depends upon the decomposition of organic matter 7mostly of the cellulose group7 derived partly from the roots1 partly from the leaves and stems of plants growing and dying on the soil1 its accumulation near the surface is natural4 ,but since the depth to which roots penetrate varies greatly not only with different plants1 but very essentially in conformity with the greater or less penetrability of the soil and subsoil1 the depth to which the dark humus tint may reach vertically varies correspondingly1 from two or three inches to several feet4 ,in the case of soils that have been formed by the gradual filling-up of swamps or marshes1 the humus-tint may reach to several yards depth4 ,surface ,soil1 and ,subsoil4--,it is thus apparent that the term 8surface soil10 while commonly confined by the farmer to the portion turned by the plow or usually reached in cultivation by any implements1 may or may not belong1 functionally1 to layers of greatly varying thickness4 ,similarly the term subsoil may or may not refer1 in individual cases1 to parts of the soil mass materially different from the surface soil4 ,yet this distinction is of no mean practical importance1 because the efficacy of one of the most common measures of soil improvement1 viz41 subsoil plowing or 8subsoiling10 depends materially upon the differences between soil and subsoil in each particular case4 ,most of the diversity of opinion regarding the merits of this operation is simply the result of a corresponding diversity in the natural facts and cultural practice of each case4 ,causes of the ,differentiation of ,soil and ,subsoil4--,one of the prominent points of difference between surface soils and subsoils has already been mentioned in the usual predominance of root-mass in the upper layers2 to which is added a part at least of the substance of fallen leaves and stems of its vegetation4 ,how much of this vegetable mass ultimately becomes converted into humus1 as well as the nature of the product formed1 depends upon a great variety of circumstances2 some of which have already been mentioned in connection with the general discussion of humification 7chapt4 #b1 p4 #bj74 ,briefly stated1 the main controlling conditions are3 the amount of water or moisture present1 the access of air 7oxygen71 a proper temperature1 and the presence of the several organisms which in the course of time take part in the process of soil-formation4 ,ulmin ,substances2 ,sour ,humus 7,germ4 ,rohhumus74--,in the presence of so much moisture or liquid water as will materially impede the access of air1 and with the concurrence of reasonably low temperatures1 the organisms that at first take the chief role in the transformation of the vegetable tissues into humus-like substances are bacteria4 ,but the antiseptic nature of the compounds thus formed#cf soon puts an end to their activity1 and thereafter the process seems to be a purely chemical one1 and very slow4 ,in peat bogs1 the transition from the fresh1 dead stems and roots to brown peat is easily followed downward1 white cellulose fibers remaining apparently unchanged to some depth2 so that such fiber has been used for tissues and paper4 ,the solid decomposition-products are brown substances1 partly soluble in water and imparting to it a brown or coffee color 7frequently seen in the drains of marshes7 and an acid reaction2 the latter due to ulmic 7as well as apocrenic7 acid1 readily soluble in caustic and carbonated alkalies1 and forming insoluble salts with the earths and metals2 while another portion1 ulmin1 is insoluble in the same1 but gradually becomes soluble by oxidation4 #cf ,the antiseptic properties of sour humus are well exemplified in the perfect state of preservation in which the remains of animals1 wood implements1 etc41 are found in bogs into which they have sunk in prehistoric times4 ,the gaseous products formed under these conditions are carbonic dioxid and 8marsh gas0 7methan1 ,,ch71 the former predominating in the early stages2 while later1 the carburetted hydrogen predominates1 rendering the gas readily inflammable4 ,sour ,soils4--,the 8sour0 soils thus produced in nature in presence of excess of water bear only 8sour0 growth1 such as sedges and rushes1 of little agricultural value2 they usually require reclamation processes before becoming adapted to ordinary crops4 ,in old forests of northern climates a peaty and more or less acid layer is sometimes formed on the surface1 above the black woods-earth1 and retards somewhat the full production of such land when taken into cultivation4#cg #cg ,see ,mller1 ,natrliche ,humusformen4 ,marshes and swamps1 both fresh and salt1 as above stated usually show coffee-colored waters1 which are also characteristic of the streams that drain them1 until by intermixture with waters containing lime salts1 the ulmic substances are neutralized and precipitated4 ,such neutralization1 preferably by means of lime1 is the first step towards the reclamation of lands bearing 8sour0 vegetation4 ,the acid reaction characterizing the ulmic substances is also characteristic of many woodlands1 notably in the ,united ,states of the soils of the 8,long-leaf-pine0 region of the ,cotton ,states1 both upland and lowland1 as well as of many deciduous forests in northern climates4 ,hence liming1 whether artificial or natural1 effects a most notable improvement1 together with a marked change of vegetation1 in these lands4 ,it has been long known that after long-continued cultivation1 soils originally of neutral or slightly basic reaction become acid3 and the liming of such lands is an ancient practice in ,europe4 ,the matter1 however1 received but scant attention until ,wheeler and ,hartwell1 of the ,rhode ,island ,experiment ,station1 demonstrated the almost universal acid condition of the older lands of that ,state1 and the excellent effects produced by neutralization with lime1 or even with the alkali carbonates4#ch ,the current neutralization of the humus-acids is unquestionably one of the cardinal advantages of calcareous lands2 for such as contain only small amounts of lime carbonate will of course become acid more quickly under cultivation4 #ch ,reports of the ,rhode ,island ,exp't ,station1 #ahie1 and ff4 ,humin ,substances4--,in the presence of only a moderate amount of moisture1 therefore under the influence of a more or less rapid circulation of air1 and in the presence of earthy carbonates 7especially that of lime7 to prevent the formation of acids1 or to neutralize them as formed1 the normal process of humification occurs2 mainly under the influence of fungous instead of bacterial growths4 ,the various molds take a prominent part in the conversion of the vegetable substance into black1 neutral1 insoluble humus compounds4 ,such fungous vegetation is always accompanied by the evolution of carbonic gas1 and the resulting fungous tissues are markedly richer in nitrogen and carbon than the substance of the higher plants from which they were derived 7see chapt4 #i74 ,comparative analyses show that in the normal process of humification of vegetable substances1 oxygen and hydrogen are eliminated in the form of water and carbonic dioxid1 while at the same time there is an increase in the percentage of carbon1 and generally also of nitrogen2 the latter more particularly in the case of vegetable matter not very rich in that element4 ,when once humification is complete1 oxidation1 especially under arid conditions1 bears mainly upon the carbon and hydrogen1 so that the nitrogen content may rise to very high figures2 while another portion is ultimately wholly oxidized1 with the formation of nitrates1 under the influence of the nitrifying bacteria1 this being the process chiefly efficient in the nutrition of vegetation with nitrogen4 ,as a matter of course1 the several organic compounds contained in plants may continue to exist in soils for some time1 varying according to conditions of temperature and moisture4 ,thus dextrin1 glucose1 and even lecithin and nuclein have been reported to be found4 ,the activity of the numerous fungous and bacterial ferments under favoring conditions will1 of course1 limit the continued existence of such compounds somewhat narrowly1 so that they can hardly be considered as active soil ingredients save in so far as they favor the development of the bacterial flora4 ,porosity of ,humus4--,one of the essential features of natural humus is its great porosity1 whereby it not only becomes highly absorbent of water and gases1 but is also gradually oxidized1 probably under the influence of bacteria4 ,for this oxidation1 as measured by the evolution of carbonic gas1 progresses most rapidly under the same conditions as to moisture1 temperature and access of air1 that are known to be most favorable to fungous and bacterial growth4 ,hence the formation of carbonic dioxid in the soil is assumed to be the measure of the intensity of such activity4 ,physical and ,chemical ,nature of the ,humus ,substances4--,the humus substances are gelatinous when moist1 but are neither markedly adhesive or plastic4 ,like the other colloidal substances of the soil1 they serve to retain both gases and vapors1 including moisture1 liquid water1 and its dissolved solids4 ,in the natural1 porous condition they are powerfully absorbent of gases1 including especially aqueous vapor4 ,dry humus swells up visibly when wetted1 the volume-weight increasing to the extent of two to eight times2 so that humus stands foremost in this respect among the soil constituents4 ,the density of natural humus is about #a4d1 being the lightest of the soil constituents4 ,hence soils rich in humus are 8light0 not only in the farmer's sense of being easily tilled when not too wet1 but also of light weight for equal volumes when compared with clayey and sandy soils4 ,some data bearing upon these points are given in the table#ci below1 for the substances moderately and uniformly packed3 ,,volume-,,weights ,,of ,humus4#dj ,clay4 ,quartz ,sand4 4#ccdi #a4jajh #a4ddhe ,when saturated with water1 the same substances gave the following figures3 ,air-dry4 ,saturated ,increase4 with water4 ,humus#da 4#cefe #a4ajbd #bji4b ,clay #a4jcie #a4fbfh #ee4i ,quartz sand #a4dejh #a4hbgj #be4i #ci ,wollny1 ,zersetzung der ,organischen ,stoffe1 pp4 #bdb1 #bdc4 #dj ,peat pulverized and extracted with alcohol and ether to remove resinous substances4 #da ,peat pulverized and extracted with alcohol and ether to remove resinous substances4 ,these data show strikingly the effects produced by the several physical soil constituents upon some of its physical properties4 ,chemical ,nature4--,while humus artificially produced by the action of caustic alkalies upon sugar or cellulose is free from nitrogen1 all naturally occurring humus contains the latter4 ,it is not1 however1 present in the form of ammonia1 as it cannot be set free by treatment in the cold with lime or alkalies4 ,when1 however1 natural humus is boiled with these substances1 ammonia is slowly given off1 but the process continues indefinitely and it seems to be impossible to expel all the nitrogen in this manner4 ,this behavior being characteristic of amido-compounds1 it is presumable1 in view of the slightly acid nature of the humus substances1 that natural humus is largely of an amidic constitution4 ,artificial humic acid1 formed by the action of caustic alkalies upon sugar1 gums or cellulose1 combines with ammonia as with other bases1 and at first the ammonia can be readily expelled from this as from other ammonia salts4 ,but after the lapse of some time it seems that the amidic condition is assumed1 so that caustic lye acts but very slowly and cannot expel the whole of the nitrogen present4 ,this is very important in connection with the practice of fertilization1 as any ammonia taken up by or generated in the soil is thus in the course of time rendered comparatively inert1 and unavailable to vegetation until nitrified4 ,progressive ,changes4--,the natural neutral humin and ulmin1 as found1 e4 g41 in the lower portions of peat beds1 are in the course of time by oxidation converted into ulmic and humic acids1 capable of combining with bases2 by still farther oxidation they form apocrenic and crenic acids1 readily soluble in water and in part forming soluble salts with lime1 magnesia and other bases4 ,these acids act strongly upon the more readily decomposable silicates of the soil1 and in the course of time may dissolve out1 and aid in the removal by leaching1 of most of the plant-food ingredients as well as the ferric hydrate of a soil4 ,thus red or rust-colored soils may be rendered almost white by continued 8swamping0 with stagnant water1 and be greatly impoverished2 and it is doubtless largely through this agency that the underclays of coal beds and the lower portions of peat beds1 as well as peat and coal ashes1 are almost wholly destitute of mineral plant food4 ,the ,phases of ,humification4--,the progressive changes involved in the process of humification of vegetable matter are illustrated in the table below1#db together with the farther changes by which such matter may ultimately be transformed into the several varieties of coal1 and finally into anthracite1 which already represents nearly pure carbon1 but in nature has sometimes been still farther transformed into graphite 7black-lead7 and diamond4 #db ,data recalculated1 omitting ash4 ,,progress ,,of ,,humification1 ,,and ,,formation ,,of ,,coal4 7,,moisture ,,and ,,ash ,,omitted ,,from ,,calculations47 ,oak ,wood4 -------------------- ,humin ,cellulose4,fresh4,decayed4 and -------------- ,humic ,light ,dark ,acid4 ,brown4 ,brown4 ---------------------------------------- ---------- ,carbon #dd4dd #ej4fj #ec4fj #ef4bjdi4d to #ei4g ,hydrogen #f4ag #f4jj #e4bj #d4ij #b4e 8 #d4e ,oxygen #di4ch #ce4h 8 #dg4c #dc4dj #da4bj #ch4ij ,nitrogen 4#c 8 #ah4g ---------------------------------------- ---------- ,peat4#dc ,coals4 ---------------------------------------- ----------- ,brown ,black4 ,lignite ,scotch ,penn'a ,surface4------------ ,brown ,splint ,anthracite4 7,ulmin47#dj in4#hj in4 ,coal4 ,bituminous4 7,bovey74 ---------------------------------------- ------------------ ,carbon #eg4hj #fb4jj #fd4aj #fi4ej #hd4bj #id4hj ,hydrogen #e4dj #e4bj #e4jj #e4ij #e4hj #b4fj ,oxygen #cf4jj #cj4gj #bf4hj #bd4jj #h4hj #b4fj ,nitrogen 4#hj #b4aj #d4aj 4#fj #a4bj ---------------------------------------- ----------------- #dc ,detmer1 ,landw4 ,versuchst41 ,vol4 #ad1 #ahga4 ,the steady increase of carbon and nitrogen1 together with a corresponding decrease of oxygen1 are well illustrated in the analyses1 especially in the strictly comparable series of peat samples from various depths4 ,in this case there is also a steady decrease of hydrogen1 and an increase of ash from #b4gb in the surface layer1 to #i4af at #hj inches depth4 ,this increase is due in the main1 of course1 to the progressive volatilization of the organic matter in the forms of carbonic dioxid and marsh gas 7methan1 ,,ch74 ,in considering this table it should not be forgotten that while normal humus stands very close to peat1 and the latter when compressed in certain stages would be undistinguishable from lignite or brown coal2 yet both peat and lignite are known to be formed under conditions permitting much less access of air or oxygen than occurs in the formation of normal black soil-humus4 ,hence even black peat cannot at once stand in place of soil-humus when removed from its watery bed1 but requires considerable time and aeration 7oxidation71 and in most cases neutralization with lime or marl1 before it can serve the purposes of humus in the soil4 ,lignite and the progressively more carbonaceous coals are and have been formed under the conjoined action of submergence and pressure1 sometimes also aided by heat2 and thus they cannot perform the function of soil-humus1 any more than the fire-clays or shales underlying them can resume their original soil-functions without prolonged weathering4 ,amounts of ,humus and ,coal ,formed from ,vegetable ,matter4--,only very general and indefinite estimates can be given of the amount of humus or coal formed from a given quantity of vegetable matter1 since these must vary according to the conditions under which the transformation occurs4 ,the greater or less access of air and of moisture1 the temperature and pressure under which the process occurs1 will modify very materially the quantitative as well as the qualitative result4 ,in the hot arid regions the fallen leaves may wholly disappear by oxidation on the surface of the ground1 while under humid conditions they are mostly incorporated with the surface soil4 ,if we assume that in the humification of plant debris 7estimating their average nitrogen content at #a71 no nitrogen is lost1 it would seem that in the humid region one part of normal soil-humus might be formed from #e to #f parts of 7dry7 plant debris2 while in the extreme regime of the arid regions1 from #ah to #bj parts of the same would be required4 ,but as most probably some nitrogen also is lost in the process of humification1 a considerably larger proportion of original substance may be actually required4 ,illustration3 ,,fig4 #ad4--,section of lignitized log showing contraction into solid lignite on drying4 ,as to coal1 it is usually assumed that it requires about #h parts of vegetable matter for one of bituminous coal4 ,much higher estimates are made by some1 and an observation made by the writer at the ,port ,hudson bluff1 ,mississippi1 in #ahfi1 would seem to justify such estimates4 ,the above figure1 from a sketch made at the time1 shows the proportions to which a pine log about eight inches in diameter had shrunk in drying into a small sheet of lignitized wood2 the original trunk1 projecting from a bed of sand some forty feet below the surface1 being so porous and spongy that when wet it flattened somewhat by its own weight2 it was connected with the little sheet of lignite by a spirally twisted1 tapering stipe4 ,here evidently the proportion of lignite formed was a very minute one1 doubtless because of the long leaching to which the trunk had been subjected4 ,it thus seems impossible1 as in the case of humus1 to assign any definite proportion as between woody matter and coal formed from it4 ,normal humification takes place only under the influence of moderate temperature4 ,when the temperature is too low1 bacterial and fungous growth are repressed or arrested2 when too high1 the fungous vegetation assumes a different phase1 the result of which is the almost total oxidation of the organic matter1 sometimes so accelerated as to initiate rapid combustion 8fire-fanging0 of dung2 leaving in any case but a trifling organic residue of very high ash contents4#dd #dd ,a striking illustration of this is afforded by ,naegeli's experiment of enclosing several loaves of bread in a loosely closed tin-box4 ,after eighteen months there remained only seventeen per cent of air-dry mouldy matter1 totally destitute of starch4 ,eremacausis4--,in the absence of a sufficient degree of moisture to co-operate with the other agencies of humification1 the final result in the soil is practically the same as in the 8fire-fanging0 of dung4 ,the organic matter is almost wholly destroyed by direct oxidation 7eremacausis7 with or without the aid of minute organisms2 leaving essentially only the ash behind to be reincorporated with the soil4 ,this is to a very great extent the predominant process in the arid regions of the ,globe2 most of the soils formed in these climates being1 therefore1 very poor in humus-substances1 and deriving it almost entirely from the decay of roots only4 ,the extent to which the humus of a soil may be derived from the vegetable debris falling or growing upon the surface1 varies greatly with the climatic conditions as well with the nature of the soil4 ,in the forests of humid climates with loamy soils1 not only does the autumnal leaf-fall1 as well as decaying twigs and trunks1 become obviously incorporated with the surface soil as decay progresses on the lower surface1 but active animal agencies 7see below7 carry the organic remnants bodily down4 ,but where heavy clay soils prevail1 these animal agencies are much restricted by the compactness of the material2 only a light surface-layer of mold would be formed1 and the humus of the lower soil layers must of necessity be derived from the decay of the roots only4 ,this origin is claimed by ,kosticheff#de for the high content of black humus in the tchernozem or black earth of ,russia4 ,following ,hellriegel in determining the weight of roots contained in successive equal layers of soil from the surface downwards1 ,kosticheff gives for each six inches the following data as found in the tchernozem1 taking as #ajj the root-content of the surface layer3 ,number4 #a #a #b #b #c #c ,depth4 ,roots4,humus4,roots4,humus4,roots4,humu s4 ---------------------------------------- ------- #f inches4 #ajj4 #e4db #ajj4 #h4aa #ajj4 #i4fd #ab 8 #hi4a #d4hc #fc4i #e4ai #hj4c #g4gg #ah 8 #ff4i #c4fb #dh4c #c4ib #gj4j #f4ga #bd 8 #dg4c #b4ef #ce4j #b4hd #eh4d #e4fa #cj 8 #dg4c #b4ei #bf4j #b4aa #ch4b #c4eg #cf 8 #cd4f #a4hh #ah4a #a4dg #cc4j #c4ah #db 8 #bc4i #a4bi #f4c 4#ea #af4b #a4ef #dh 8 #ad4d 4#gh 4#gj #ed 8 #f4g 4#cf ---------------------------------------- ------- #de ,abstract in ,ann4 de la ,science ,agronomique1 ,tome #b1 #ahhg4 ,it will be seen that there is a very close correspondence of the humus content with the root development in the several layers1 and it seems as if though but little of the humus could be derived from the surface growth1 which is that of the grasses of the steppe4 ,the climate of the black-earth country of ,russia is1 though not properly arid1 yet one of rather deficient and uncertain rainfall4 ,but as a consequence of extremely arid conditions1 and in sandy lands1 it may even happen that the immediate surface soil contains less humus than what1 in the farmers' habitual parlance1 would be called the subsoil2 because of the penetration of slow combustion for some distance into the porous soils4 ,it will then be lower down that1 in the presence of a favorable degree of moisture and lower temperature1 the conditions of normal humification are fulfilled4 ,it is not always1 then1 that the commonly recognized distinction between surface soil and subsoil based upon humus content can be maintained4 ,but the observation of everything bearing upon this point is of the utmost importance in determining both the agricultural value and the mode of treatment of the land4 ,losses of ,humus from ,cultivation and ,fallowing4--,the fact that humus accumulates in woodlands and meadows1 where no cultivation is given1 would naturally lead to the converse conclusion1 viz41 that cultivation causes loss of humus and of its constituents4 ,that this is actually the case is recognized and widely acted upon in practice1 and there is no question that the general acceptance of stable manure as the most widely useful fertilizer1 despite its usually low content of plant-food ingredients1 is based upon the fact that it supplies vegetable matter1 in a condition highly favorable to its conversion into humus4 ,the most direct and cogent proof of the depletion of the soil of both humus and nitrogen by continuous cultivation of cereal grains has been given by ,snyder1#df who determined the loss both of humus and of nitrogen suffered by a ,minnesota soil during eight years' continuous cultivation of wheat4 ,the total loss of nitrogen was #agjj pounds per acre1 while only #cej pounds were utilized by the crop2 about #adjj pounds being dissipated as gas or leached out as nitrates4 ,a conservative estimate of the loss of humus suffered during the same period was about a ton per acre annually1 and this loss seriously decreased not only the nitrogen-content1 but rendered the soil more compact and less retentive of moisture4 ,but by rotation of the wheat with clover in alternate years1 very nearly an equilibrium of both humus and nitrogen-content was obtained4 ,in addition1 the amount of available mineral plant-food was decreased by continuous grain culture4 ,ladd has made similar observations in ,north ,dakota1 with similar results4 #df ,bull4 ,no4 #gj ,minn4 ,exp't ,station1 #aije4 ,that excessive aeration results in serious losses of humus as well as of nitrogen1 is very obvious in the arid region1 where it is the habit to maintain on the surface of orchards and vineyards during the dry1 hot summers1 a thick mulch of well-tilled soil1 thus preventing loss of water by evaporation4 ,in the course of years this surface soil becomes so badly depleted of humus that good tilth becomes impossible1 the soil becoming light-colored and compacted2 while the loss of nitrogen is indicated by the small size of the orchard fruits4 ,similar losses are of course sustained in the practice of bare summer-fallow1 which at one time was almost universal in portions of the arid region4 ,the complete extirpation of weed growth thus brought about1 at first considered an unmixed benefit1 has ultimately had to be made up for by the practice of green-manuring2 since in the arid region the use of stable manure encounters many difficulties4 ,estimation of ,humus in ,soils4 ,it has been usual to determine the amount of humus in soils by means of 7dry or wet7 combustion1 calculating the humus from the carbonic dioxid so formed1 while measuring the nitrogen gas directly4 ,but in this process the entire organic matter of the soil1 humified and unhumified1 is indiscriminately included2 and it is wholly uncertain to what extent the latter will ultimately become humus1 from the nitrification of which plants are presumed to chiefly derive their nitrogen4#dg ,in order to obtain definite results1 the actual1 functional humus must be extracted from the soil mass by some solvent which discriminates between the humified and unhumified organic matter4 ,this cannot be done by direct extraction with caustic soda or potash1 which inevitably dissolve unhumified matters and tend to expel ammonia from the humus2 besides themselves acting as humifiers 7see this chapter1 p4 #abe47 ,grandeau ,method3 ,matire ,noire4--,the only method now known which accomplishes this separation1 practically excluding the unhumified while fully dissolving the humified matter--is that of ,grandeau3 the extraction of the soil1 first with dilute acid1 in order to set the humic substances free from their combinations with lime and magnesia2 and their subsequent extraction with moderately dilute solutions of ammonia 7or other alkali hydrates74 ,upon the evaporation of the ammonia solution the humus is left behind in the form of a black lustrous substance 78matire noire0 of ,grandeau7 much resembling the crust of soot formed in flues from wood fires4 ,as it contains a variable amount of ash1 it must be burnt and the ash subtracted from the first weight4 #dg ,the humus determinations thus made1 which include nearly all those made by ,german chemists1 give the humus-content from #dj to #ej too high4 ,the ,french determinations are mostly made by the method of ,grandeau4 ,amounts of ,humus in ,soils4--,while in peat1 marsh and muck lands the humus-content may rise above twenty per cent1 in ordinary cultivated lands it rarely exceeds about five per cent1 and very commonly falls below three per cent1 even in the humid regions4 ,in properly arid soils we find a very much lower average1 rarely exceeding one per cent1 and frequently falling to 4#cj and even less4 ,this scarcity of humus manifests itself plainly in the prevalently light gray tint of the arid soils4 ,meadows and woodlands generally show the highest humus-content in their surface soils1 gradually increasing while in that condition2 while when taken into cultivation the humus-content gradually decreases1 owing to the free aeration and consequent 8burning-out0 caused by tillage4 ,hence the humus must be from time to time replaced by the use of stable manure1 or green-manure crops1 to prevent injurious changes in the tilling qualities of the land4 ,not only humus as such1 but according to ,schloesing also the insoluble colloid humates1 produce in the soil a loosening effect or tilth 7,germ4 ,bodengare71 which apparently cannot be brought about by any other substance4#dh #dh ,the decrease of humus from wheat culture in the soils of ,minnesota and ,north ,dakota has been studied by ,h4 ,snyder and ,e4 ,f4 ,ladd1 respectively4 ,in the prairie lands of the latter ,state the total organic matter in the first six inches of soil ranges from #ae to as much as #bf1 and the humus alone from #d to #g4h4 ,humates and ,ulmates4--,that the insoluble humates of lime1 magnesia1 iron1 manganese and alumina are present in most soils is conclusively shown by the composition of the solution obtained by the extraction of soils with weak acid1 as above mentioned in connection with the quantitative determination of humus according to ,grandeau2 since these bases are almost always extracted by the weak acid4 ,when the brown solution of alkali humate obtained in this process is carefully neutralized with sulfuric or hydrochloric acid1 or is mixed with solutions of the above bases1 flocculent1 insoluble precipitates are formed1 while the solution is discolored4 ,similar precipitates may be obtained with other metallic solutions1 notably with that of copper1 which precipitates the humus-acids most completely4 ,doubtless these compounds contribute greatly to the conservation of the humus-content of soils1 protecting it to a certain extent from oxidation1 and also preventing excessive acidity4 ,the brown tint of certain subsoils in the northern humid regions have been shown by ,tollens and others to be due not to ferric hydrate1 as had been supposed1 but to calcic1 magnesic and aluminic humates4 ,none of the mineral bases or acids present can be detected in the humic solution by the usual reagents4 ,mineral ,ingredients in ,humus4--,that the mineral plant-food ingredients present in the humus extracted by the ,grandeau process1 and which remain as ash when the matire noire is burned1 are capable of nourishing plant growth1 was directly shown by ,grandeau1 ,snyder and others4 ,the former was inclined to consider that those substances were mainly thus taken up by plants1 under natural conditions4 ,this theory1 however1 has not been sustained by subsequent investigations2 the mineral plant-food thus extracted is not a measure of the immediate productiveness of the soils1 as demonstrated by ,snyder1 and the residual soils are not sterile4 ,it is also still doubtful to what extent the mineral bases and acids are naturally combined with the humus-substances1 it being contended by some that they are brought into organic combination by the acid and ammonia extraction4 ,the investigations of ,snyder and ,ladd1 above referred to1 prove however to some extent at least that the humus-substances are naturally combined with them1 and that probably they are largely made available to plants through the direct and indirect action of the humus compounds4 ,this subject is farther considered in chapter #ai4 ,the nature and amounts of these mineral substances are well exemplified in the subjoined full analysis by ,snyder1 of the ash of the humus and humates extracted from a compound sample of prairie soils of ,minnesota1 which had been thrown down from the ammonia solution by simply neutralizing the liquid3#di ,,ash ,,of ,,humus ,,from ,,minnesota ,,prairie ,,soils4 ,insoluble matter#ej #fa4ig ,potash 7,k,o7 #g4ej ,soda 7,na,o7 #h4ac ,lime 7,ca,o7 #j4ji ,magnesia 7,mg,o7 #j4cf ,peroxid of ,iron 7,fe,o7 #c4ab ,alumina 7,al,o7 #c4dh ,phosphoric acid 7,p,o7 #ab4cg ,sulfuric acid 7,,so7 4#ih ,carbonic acid 7,,co7 #a4fd #di ,precipitation with an excess of acid does not greatly change the results4 #ej ,in ,california soils this is mostly silica soluble in carbonate of soda4 ,the large amounts of the soluble alkalies potash and soda thrown down with the humic matters are very striking1 as is the very large proportion of phosphoric acid4 ,lime and magnesia had1 of course1 been mainly eliminated by the preliminary acid treatment4 ,functions of the ,unhumified ,organic ,matter4--,the unhumified plant debris in the soil are not to be regarded as useless1 even aside from their potential conversion into active humus4 ,not only do these remnants of vegetation lighten the soil1 rendering it more pervious to air and water1 but in their progressive decay they give off carbonic gas1 which is active in soil-decomposition2 and they serve as nourishment to the soil bacteria upon which its thriftiness so greatly depends4 ,see below1 chapter #i4 ,the ,nitrogen-,content of ,humus4--,since soil-humus is doubtless the chief depository of soil-nitrogen1 and the main source from which1 through the process of nitrification1 the nitrogen-supply to plants is usually derived1 its content of that element is a matter of great interest4 ,it has been customary to estimate approximately the nitrogen-content of soils by the proportion of humus-substance present2 and as the light tints of the soils of the arid region indicate a small humus-content1 a scarcity of nitrogen seemed to be also indicated for these lands4 ,as this in a number of cases did not seem to accord with actual experience1 an investigation of the subject was made at the ,california experiment station1#ea with the results shown in the subjoined table4 ,in considering these results it must be kept in mind that while arid conditions can rarely be fulfilled in the humid region1 humid conditions are quite frequently locally represented in the arid1 in lowlands and on high mountains2 while moderately moist benchlands represent the semi-arid regime4 #ea ,hilgard and ,jaffa4 ,on the ,nitrogen-content of ,soil-humus in the ,humid and ,arid regions4 ,rep4 ,cal4 ,exp't ,station for #ahib-d2 ,agric4 ,science1 ,april1 #ahid2 ,wollny's ,forsch4 ,geb4 ,agr4 ,phys41 #ahid4 ,,humus ,,percentage ,,and ,,nitrogen ,,content ,,in ,,soils ,,of ,,the ,,arid ,,and ,,humid ,,regions4 ,humus,nitrogen,nitrogen ,station ,soils arranged in order of nitrogen in in in ,number percentages in humus4 soil1 ,humus1 soil1 per per per cent4 cent4 cent4 ---------------------------------------- -------------------------------- ,,soils ,,of ,,the ,,arid ,,region 7,california74 #bjfa ,dark clay loam1 ,arroyo ,grande ,valley1 #c4jf #bb4jj 4#fgj ,san ,luis ,county #bbia ,red soil1 ,orland1 ,glenn ,co4 4#ga #ba4aj 4#aej #aijd ,sediment ,soil1 ,porterville1 ,tulare ,co4 4#ij #ai4ej 4#ahj #aija ,sandy soil near ,ceres1 ,stanislaus ,co4 4#fd #ah4ge 4#abj #gjd ,sandy soil of plains1 near ,fresno1 ,fresno ,co4 4#fj #ah4ff 4#aab #f ,black adobe soil1 ,stockton1 ,san ,joaquin ,co4 #a4je #ah4ff 4#aif #afgi ,black adobe soil1 ,berkeley1 ,alameda ,co4 #a4bj #ah4eh 4#bjc #bcbd ,clay soil of desert1 ,imperial1 ,san ,diego ,co4 4#ch #ah4dj 4#jgj #aafg ,black clay loam soil1 near ,tulare1 ,tulare ,co4 #a4ff #ah4ai 4#cjb #aecf ,brown loam soil1 ,windsor ,tract1 ,riverside1 4#bj #ah4jj 4#jcf ,riverside ,county #aabf ,sandy loam soil1 ,paso ,robles1 4#ee #ag4bg 4#jie ,san ,luis ,obispo ,co4 #bcja ,red hill soil1 ,upper ,lake1 ,lake ,co4 4#ha #af4ij 4#acg #afjg ,plateau soil of desert1 ,lancaster1 4#be #af4hj 4#jdb ,los ,angeles ,co4 #aaei ,sandy plains soil1 ,tulare1 ,tulare ,co4 4#cg #af4ge 4#jfb #aijj ,sandy soil1 near ,modesto1 ,stanislaus ,co4 4#hd #af4fe 4#adj #aaac ,clay loam soil 7slate71 ,jackson1 ,amador ,co4 4#ed #af4fj 4#jij #aadi ,adobe clay soil1 near ,paso ,robles1 4#dg #af4ah 4#jgd ,san ,luis ,obispo ,county #aech ,mesa soil1 ,chino1 ,san ,bernardino ,co4 4#fe #af4jh 4#aje #aadg ,sandy loam soil1 ,paso ,robles1 4#ff #af4jf 4#ajf ,san ,luis ,obispo ,co4 #bdjc ,valley ,soil1 ,wheatland1 ,yuba ,co4 #a4ej #af4jj 4#bdj #abha ,red ,mesa soil1 ,pomona1 ,san ,bernardino ,co4 4#eh #ae4ej 4#jij #aaag ,sandy granitic soil1 near ,jackson1 ,amador ,co4 4#hj #ae4bg 4#abc #adjf ,red loam soil1 ,arlington ,heights1 ,riverside1 4#cj #ae4jj 4#jde ,riverside ,county #aagb ,red clay loam soil1 east of ,tulare1 ,tulare ,co4 4#gb #ad4ge 4#ajf #aieh ,sandy ,mesa soil1 ,nipomo1 ,san ,luis ,obispo ,co4 4#he #ad4de 4#abb #adbc ,chocolate-red soil1 ,carisa plain1 4#ci #ad4cf 4#jef ,san ,luis ,obispo ,county #abia ,sandy hill land1 near ,jackson1 ,amador ,co4 4#gf #ad4cd 4#aji #ehe ,wire-grass loam soil1 ,visalia1 ,tulare ,co4 #a4jj #ad4aj 4#adf #hfc ,red ridge loam soil1 ,grass ,valley1 ,nevada ,co4 #b4hi #ac4ia 4#djb #aijg ,dark loam soil1 near ,chino1 ,san ,bernardino ,co4 4#ib #ac4bf 4#aba #aaae ,sandy granitic soil1 near ,jackson1 ,amador ,co4 4#he #ac4bj 4#aab #ccb ,plateau desert soil1 ,mojave1 ,los ,angeles ,co4 4#bh #ab4ej 4#jce #babf ,gravelly soil1 ,east ,highlands1 4#fb #aa4ge 4#jgj ,san ,bernardino ,co4 #aiaj ,ojai ,valley soil1 ,nordhoff1 ,ventura ,co4 #a4fd #aa4ba 4#ahc #bahg ,sandy loam soil1 ,soledad1 ,monterey ,co4 4#ig #aa4aj 4#aaj #agei ,sandy soil1 ,perris ,valley1 ,riverside ,co4 4#ec #aa4jd 4#jei #ggd ,bench slope soil1 ,ontario1 ,san ,bernardino ,co4 #a4bi #aj4he 4#adj #aihd ,red soil1 ,east ,highlands 8 8 8 4#eh #aj4ej 4#jfj #bcbe ,silt soil of desert1 ,imperial1 ,san ,diego ,co4 4#fe #aj4gj 4#jgj #aijf ,light sandy soil1 ,pomona1 ,san ,bernardino ,co4 4#ie #i4hj 4#jic #bdcj ,hillside adobe1 ,berkeley1 ,alameda ,co4 #a4he #h4gj 4#afj --------------------- ,average of arid uplands 4#ia #ae4bc 4#ace ,,sub-,,irrigated ,,arid ,,soils 7,california74 #ehf ,sandy plains soil1 ,tulare1 ,tulare ,co4 #a4ad #aj4gi 4#abc #adff ,loam soil1 ,miramonte1 ,kern ,co4 4#fj #aj4ff 4#jfd #abhd ,moist land loam soil1 ,chino1 #a4ii #aj4bj 4#bjc ,san ,bernardino ,co4 #aadh ,swale soil1 near ,paso ,robles1 #a4af #i4fe 4#aab ,san ,luis ,obispo ,co4 #agad ,bench soil1 ,santa ,clara ,river1 ,piru1 4#gh #i4ef 4#jgd ,ventura ,co4 #gg ,alluvial soil1 ,tulare ,lake bed1 ,tulare ,co4 4#dg #i4cg 4#jde #ahhj ,creek bench soil1 ,niles1 ,alameda ,co4 #a4ai #h4ij 4#aji #aijc ,sediment soil1 ,porterville1 ,tulare ,co4 #a4ab #h4ej 4#adj #afh ,alluvial soil1 ,santa ,clara river1 ,santa ,paula1 4#hd #g4ii 4#jfg ,ventura ,co4 #agfj ,green-sage land1 ,perris ,valley1 ,riverside ,co4 4#ia #g4gj 4#jgj #ejf ,alluvial soil1 ,colorado ,river1 ,yuma1 4#ge #g4dg 4#jej ,san ,diego ,co4 #afcf ,red soil1 ,manton1 ,tehama ,co4 #b4jj #f4hf 4#acg #ageh ,alkali soil1 ,perris ,valley1 ,riverside ,co4 4#fj #f4hc 4#jga #aifc ,sandy loam soil1 ,willows1 ,glenn ,co4 4#cf #f4je 4#jbb #bjhj ,sandy soil1 ,santa ,maria ,valley1 #a4fd #e4cf 4#jij ,santa ,barbara ,co4 ,average of sub-irrigated arid soils #a4jf #h4ch 4#jii ,,humid ,,soils ,,from ,,arid ,,and ,,humid ,,regions 7,california74 #bjg ,eel ,river ,alluvial soil1 ,ferndale1 #a4be #f4if 4#jhe ,humboldt ,co4 #bcai ,alluvial soil1 ,hupa ,valley1 ,humboldt ,co4 #g4hc #f4gj 4#ead #bac ,marsh soil1 ,novato1 ,meadows1 ,marin ,co4 #a4ed #f4cf 4#jhi #agjd ,valley soil1 ,hollister1 ,san ,benito ,co4 4#id #e4ba 4#jdi #bbie ,tule soil1 ,upper ,lake1 ,lake ,co4 #a4gj #d4ej 4#jgg #aaj ,alluvial soil1 ,putah ,creek1 ,dixon1 ,solano ,co4 #a4ga #d4be 4#jgb #cg ,redwood ,valley soil1 ,pescadero1 ,san ,mateo ,co4 #b4bh #c4jg 4#jgj ,average for ,california #b4de #e4bi 4#ace ,,other ,,states4 #bf ,bog soil1 ,michigan#eb #cc4jb #f4jh #b4jab ,back-land clay loam1 ,houma1 ,louisiana #e4jg #d4bj 4#bah ,duff soil1 ,oregon #ac4hd #c4di 4#dhc ,sandy prairie soil1 ,harris ,co41 ,texas #b4ac #c4ff 4#ahd ,average for other ,states #g4ja #c4gh 4#bie #bc ,red soil1 ,oahu ,island1 ,hawaii 7maximum7 #a4eg #e4jg 4#jgh #bg ,guava soil1 ,hawaii ,island 7minimum7 #i4ie #a4ga 4#agj ,average of #e soils1 ,oahu ,island #c4ja #f4jg 4#bcg ,average of #b soils1 ,maui ,island #i4jg #b4ac 4#bhf ,average of #d soils1 ,hawaii ,island #f4ag #b4ed 4#adf ,average for ,hawaiian ,islands #e4bf #c4fi 4#afi ,total for ,humid soils1 average #d4eh #d4bc 4#aff ---------------------------------------- --------------------------------- #eb ,introduced only for comparison of the nitrogen percentage in ,humus and not included in the average4 ,it thus appears that on the average the humus of the arid soils contains about three and a half times as much nitrogen as that of the humid2 that in the extreme cases1 the difference goes as high as over six to one 7see ,nos4 #cg and #gjd72 and that in the latter cases1 the nitrogen-percentage in the arid humus considerably exceeds that of the albuminoid group1 the flesh-forming substances4 ,it thus becomes intelligible that in the arid region a humus-percentage which under humid conditions would justly be considered entirely inadequate for the success of normal crops1 may nevertheless suffice even for the more exacting ones4 ,this is more clearly seen on inspection of the figures in the third column1 which represent the product resulting from the multiplication of the humus-percentage of the soil into the nitrogen-percentage of its humus2 as appears in comparing the respective averages1 or ,nos4 #aafg and #aaj and others4 ,an additional consideration is the probable greater ease with which the nitrifying bacteria can act upon a material so rich in nitrogen4 ,we must not1 then1 be misled by the smallness of many humus-percentages in the arid region1 into an assumption of a deficiency in the supply of soil-nitrogen4 ,decrease of ,nitrogen-,content in ,humus with ,depth4--,since the oxidation of the carbon and hydrogen in the humus-substance1 and the consequent increase of its relative nitrogen-content1 are manifestly dependent upon the presence of air and heat1 it is reasonably to be expected that the nitrogen-percentage of the humus should decrease with the depth of the soil4 ,that this is really the case is plainly shown in the subjoined table1 which gives the humus-percentages and the nitrogen-content of the humus from the surface foot down to twelve feet1 in a soil on the bench of the ,russian ,river1 ,cal41 which is sub-irrigated1 and liable to more or less rainfall during the summer4 ,it will be seen that not only does the absolute humus-percentage decrease quite regularly down to seven feet1 at which point there evidently was at one time a strong root development1 causing a notable increase of the humus-content2 from which again there is a regular decrease down to the twelfth foot4 ,it will be noted that the nitrogen-percentage in the humus1 while not decreasing with the same regularity as the humus-content itself1 yet exhibits a general recession from #e4cj to #a4ae in the ninth foot1 to which direct oxidation doubtless never penetrates4 ,,humus ,,and ,,nitrogen-,,content ,,of ,,russian ,,river ,,soil4 ,depth in feet4 ,per cent ,per cent ,per cent ,humus ,nitrogen ,humus-,nitrogen4 in soil4 in ,humus4 in soil4 ---------------------------------------- --------------------- #a #a4ba #e4cj 4#jfd #b #a4af #d4cb 4#jed #c #a4ad #c4hg 4#jdd #d #a4ag #c4gf 4#jdd #e 4#gd #b4af 4#jaf #f 4#fj #b4ff 4#jaf #g 4#dg #b4ed 4#jab #h 4#gh #a4ed 4#jab #i 4#ed #b4bd 4#jab #aj 4#eb #a4ae 4#jjf #aa 4#ec #a4ea 4#jjh #ab 4#dd #a4ha 4#jjh ---------------------------------------- --------------------- ,influence of the ,original ,materials on the composition of ,humus4--,the great variability of the composition of humus formed from different substances is well shown in the subjoined table1 representing the results of experiments made by ,snyder1#ec who caused various substances to humify by mixing the pulverized material intimately with a soil poor in humus1 and allowing the process to continue for a year4 ,at the end of that time the humus formed was extracted by the method of ,grandeau1 outlined above1 and analyzed1 with the following results4 ,sugar4 ,oat ,green ,wheat ,sawdust4 ,meat ,cow ,straw4,clover4,flour4 ,scraps4,manure4#ed ---------------------------------------- ------------------ ,carbon #eg4hd #ed4cj #ed4bb #ea4jb #di4bh #dh4gg #da4ic ,hydrogen #c4jd #b4dh #c4dj #c4hb #c4cc #d4cj #f4bf ,nitrogen #j4jh #b4ej #h4bd #e4jb #j4cb #aj4if #f4af ,oxygen #ci4jd #dj4gb #cd4ad #dj4ad #dg4jg #ce4ig #de4fc ---------------------------------------- ------------------ #ajj4jjajj4jj #ajj4jjajj4jj #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- ------------------ #ec ,bull4 ,no4 #ec1 ,minn4 ,exp't ,station1 p4 #ab1 ,chem4 of ,soils and ,fertilizers1 p4 #id4 #ed ,the figures for cow manure are so far out of range with any others thus far observed1 that it seems reasonable to suppose that they are influenced by unchanged substances present in the excreta4 ,while it may be questioned whether the process of humification had in these materials really reached the point of sensible completion in all cases 7notably in those of sawdust and cow manure71 the great variability of the products from different materials is very striking4 ,when the nitrogen-content is deducted the percentage composition of the products agrees more nearly4 ,considering that the nitrogen is probably present in the amid form1 it is natural that hydrogen should in a measure vary with it1 as in the case of the clover1 flour and meat humus4 ,nitrogen being the most variable ingredient of humus1 it seems probable that the variation of the proportion of the humus-amids present is the most potent factor in the variability of the composition of natural soil-humus4 ,arranging these results in the order of their nitrogen-content as in the table below1 we see that the latter approximately corresponds to the original protein-content of the humified substances4 ,humus from meat scraps #aj4if ,nitrogen4 8 8 green clover #h4bd 8 8 cow manure #f4af 8 8 wheat flour #e4je 8 8 oat straw #b4ej 8 8 sawdust 4#cb ,while the above data prove the correlation between the first products of humification and the original substance1 it must be remembered that subsequently1 under proper conditions1 the nitrogen-percentage in humus may1 in the course of time1 increase very greatly1 even to a proportion considerably above that contained in flesh itself4 ,when we consider that ordinarily1 the latter1 and the albuminoid substances generally1 decompose in contact with air with an abundant evolution of ammonia compounds1 sometimes leaving only a little fat 7adipocere7 behind1 it is surprising that the decomposition within the soil should have exactly the opposite result1 viz41 an accumulation of the nitrogen4 ,the causes of this marked difference are not yet well understood1 but it is probably due to the differences in the kinds of bacteria that are active in the two cases4 ,snyder has also shown that the richer the organic matter humified is in nitrogen1 the more energetically it acts in rendering available the mineral matters of the soil for plant nutrition4 ,correspondingly1 ,ladd#ee has shown that with the increase of humus in the soil1 there is also a corresponding increase in the amounts of mineral plant-food extracted from the soil by a four per cent solution of ammonia1 such as is employed in the ,grandeau method of humus-determination4 #ee ,bull41 ,s4 ,dakota ,station1 ,nos4 #bd-cb1 #ce1 #dg4 ,,chapter ,,ix4 ,,soil ,,and ,,subsoil 7,continued74 ,,organisms ,,influencing ,,soil ,,conditions2 ,,bacteria1 ,,etc4 ,,micro-,,organisms ,,of ,,the ,,soil4 ,intimately correlated with the humus-substances of the soil1 as well as with its temporary contents of the carbohydrates 7cellulose1 gums and sugars7 from which humus is formed1 is the multitudinous flora of micro-organisms always present and exercising important functions in connection with the growth of the higher plants4 ,extended researches by ,adametz1 ,schloesing and ,mntz1 ,miquel1 ,koch1 ,fraenkel1 ,winogradsky1 ,frank and many others1 have thrown light upon the immense numbers and great variety of minute organisms1 especially of the bacterial group1 present in soils1 and upon their distribution and activities in the same4 ,it has been shown that their numbers are greatest near 7although usually not at7 the surface1 decreasing rapidly downward and generally disappearing wholly at depths between seven and eight feet2 the latter depth varying of course according to the nature and porosity of the soil1 and both depth and numbers being greatest in summer4 ,numbers of ,bacteria in ,soils4--,adametz found in one gram of soil1 #ch1jjj bacteria at the surface1 #dfj1jjj at ten inches depth2 in a loam soil at the surface #ejj1jjj1 at ten inches #dfd1jjj in each gram of earth4 ,of mould and similar fungous germs there were only #dj to #ej in the same1 #f species being true molds1 while four were ferments1 including the yeasts of wine and beer4 ,fraenkel found in virgin land from near ,potsdam1 a sudden1 marked decrease at depths of from three to five feet2 while in earth from inhabited places within the city of ,berlin1 considerable numbers were still present at eight and even ten feet1 in some cases4 ,in the researches lately made by ,hohl at the bacteriological station at ,liebefeld1 near ,bern1 it was found that in cultivated soils the number of bacteria greatly exceeds the figures given by ,fraenkel4 ,he found a gram of moist soil to contain from three to fifteen millions of bacteria4 ,in the cultivated soil of ,liebefeld he found #e1gej1jjj1 in meadow land #i1djj1jjj1 in a manure pile #dd1ejj1jjj per cubic centimeter4 ,these figures seem high for so small a quantity of material1 but taking the average size of a bacterium1 a cubic centimeter might readily contain six hundred millions4 7,grandeau1 ,ann4 ,sci4 ,agronomique1 vol4 #a1 p4 #dfa1 #aije74 ,mayo and ,kinsley 7,rep4 ,kansas ,exp't ,station for #aijb-c7 have made elaborate investigations of the numbers and kinds of bacteria found in various soils in ,kansas1 in connection with different crops4 ,it is noteworthy that in most cases their figures exceed considerably those given by ,european observers1 as they often reach high into the millions1 in one case to over fifty millions1 per cubic centimeter4#ef #ef ,the mode of statement in the paper is not always quite clear as to the manner in which the averages given were calculated4 ,it must be remembered that these data refer to cubic centimeters of soil1 or about twice the amount 7#a gram7 used by ,european observers4 ,five fields with different soils were investigated2 the land being described as follows3 8,field ,no4 #a is a black loam containing considerable humus2 field ,no4 #b is similar to field #a but contains more humus2 field ,no4 #c is a thin soil with clay gumbo subsoil2 fields ,nos4 #d and #e are black loams1 but not as rich in humus as either ,no4 #a or ,no4 #b40 ,the average bacterial contents of the several fields are given as follows3 ,field ,no4 #a #cc1ica1gdg per cubic centimeter4 8 ,no4 #b #ec1eif1jfj 8 8 8 8 ,no4 #c #gh1ecd 8 8 8 8 ,no4 #d #h1fdc1jjf 8 8 8 8 ,no4 #e #c1aib1aca 8 8 8 8,the crop records of these fields for the past ten years indicate that the crop yield has been 7more or less87 directly proportional to the bacterial content of the soil of each field2 field #b has produced the largest yield1 field #c the least40 ,unfortunately no chemical analyses of any of these soils are communicated2 but at the request of the writer samples of the soils of the first three fields were sent from the ,kansas station for humus determinations 7courteously made by ,dr4 ,h4 ,c4 ,myers71 which gave the following results3 ,field ,no4 #a #b4ai of ,humus4 8 ,no4 #b #c4jg 8 8 8 ,no4 #c #a4he 8 8 ,while these humus-percentages are not directly proportional to the bacterial content1 a favoring effect of high humus-content is clearly shown4 ,the bacterial and the humus-content of these soils are sensibly1 even if not directly1 correlated2 which might reasonably be expected1 since the organic matter and the humus are the bacterial food4 ,the investigation also showed wide differences in the bacterial content of the same soil when different crops were growing on it4 ,thus in samples taken on ,aug4 #ae1 there were found in the first twelve inches of a black loam soil bearing timothy and clover1 #a1chj1jjj1 in the same with alfalfa and clover1 #ba1jia1jjj1 with maize from one to over two millions4 ,in soils from the western part of ,kansas1 the bacterial content of the same crops was much less 7as doubtless is the humus-content71 and it is noteworthy that the prairie buffalo grass shows throughout a relatively high bacterial content in the first foot of the soil1 ranging next to alfalfa4 ,the root bacteria living on the legumes will naturally increase the bacterial content of the soils on which they grow1 more than plants which1 like maize1 do not directly utilize bacterial action4 ,multiplication of the ,bacteria4--,marshall ,ward and ,duclaux have made some special observations in regard to the rapidity with which certain bacteria multiply4 ,duclaux summarizes the final conclusion thus3 taking as a basis the time of #ce minutes for the subdivision into two1 which has been frequently observed by ,ward1 there would be four millions of bacteria produced in twelve hours4 ,the first filaments had plenty of room in a drop culture of one cubic millimeter2 but at the end their total volume amounted to the tenth part of the total volume of the drop4 ,at the above rate1 making #dh generations in #bd hours1 #bha1ejj billions of organisms would be produced4 7,grandeau1 ,ann4 ,sci4 ,agron4 ,vol4 #a1 #aije1 p4 #def74 ,aerobic and ,anaerobic ,bacteria4--,as may readily be inferred1 the cultural and other surface conditions exert a potent influence both upon the kinds and abundance of the bacteria and molds2 since the life-functions of some are dependent upon the presence of free oxygen 78aerobic071 while others flourish best1 or only1 in the absence of air 78anaerobic071 or are able to avail themselves of the presence of combined oxygen1 by reduction of oxids present4 ,their number is found1 in general1 to be greatest in cultivated lands1 and bacteria are there by far predominant over the moulds4 ,on the other hand1 the moulds gain precedence in woodlands and meadows1 at least so far as air can gain access2 while in the deeper layers of the same1 as well as in peaty lands1 bacterial life is always scanty4 ,this holds particularly in respect to the nitrifying organisms1 and others whose life-functions are dependent upon abundant access of oxygen 7aerobic74 ,food ,material ,required4--,all bacteria1 like the fungi1 are dependent for their development upon the presence of adequate amounts of some organic food-material1 best apparently in water-soluble form4 ,in the soil it seems to be chiefly compounds of the carbohydrate group1 especially various gums derived from the decaying plant substance1 or from stable manure2 in artificial cultures1 glucose is mostly found to be a highly available food4 ,when the decaying substance reaches the state of humus1 the latter seems to be available as food only to comparatively few bacteria4 ,the very abundant development of bacterial life seems to be among the most important effects produced by stable manure upon the surface soil1 in establishing good tilth 78,bodengare0 in ,german74 ,functions of the ,bacteria4--,while there is still much uncertainty as to the exact functions performed by most of these bacteria in respect to soil-formation and plant growth1 there are several kinds whose activity has been proved to be of the utmost importance in one or both directions2 it having been shown that when the soil is sterilized either by heat or antiseptic agents1 certain essential processes are completely suppressed until the soil is re-infected and the conditions of bacterial life restored4 ,probably the chief in importance are those connected with the processes of nitrification and denitrification1 bearing as they do upon the supply to plants of the most costly of the three substances furnished by fertilizers4 ,these organisms have been first extensively studied by ,winogradsky1 while the conditions of their activity have been largely developed by ,r4 ,warington4 ,illustration3 ,,fig4 #ae4--,nitrosomonas4 7,winogradsky74 ,illustration3 ,,fig4 #af4--,nitrobacterium4 7,winogradsky74 ,nitrifying ,bacteria4--,the conversion of ammonia into nitrates is accomplished under proper conditions by two organisms1 or groups of organisms2 the first stage being the formation of nitrites by the round1 often flagellate cells of nitrosomonas 7or nitrosococcus74 ,the second1 the oxidation of the nitrites into nitrates by very minute rod-shaped bacilli1 named nitrobacteria4 ,the conditions under which these bacteria can act are quite definite in that1 aside from a supply of the nitrifiable substance1 a fairly high temperature 7#bd ,c4 or #ge ,f47 and a moderate degree of moisture1 there must be a free access of oxygen 7air72 and there must be present a base 7or its carbonate7 with which the acids formed by oxidation can immediately unite4 ,in an acid medium 78sour0 soils7 nitrification promptly ceases2 as it also does whenever the amount of base present has been fully neutralized4 ,the bases most favorable to nitrification are lime and magnesia in the form of carbonates1 an excess of which does no harm2 while in the case of the carbonates of potash and soda1 the amount must be strictly limited4 ,conditions of ,activity4--,dumont and ,crochetelle found that up to 4#be per cent1 potassic carbonate acted favorably on the process2 which was1 however1 completely stopped by as much as 4#h per ct4 ,warington has shown that ammonic carbonate similarly prevents nitrification when exceeding about 4#cg per ct4 ,ammonia salts in general appear to be antagonistic to the transformation of nitrites into nitrates4 ,aside from the carbonates1 some neutral salts favor nitrification very markedly2 while others tend to depress it4 ,deherain found that 4#e per cent of common salt suffices to prevent nitrification altogether1 while smaller amounts retard it proportionally4 ,according to ,dumont and ,crochetelle1 potassium chlorid acts favorably up to 4#c per cent1 but at 4#h per cent suppresses nitrification4 ,earthy and alkaline sulfates1 on the contrary1 seem to act favorably throughout1 at least up to 4#e per cent4 ,this is especially true of gypsum1 which1 according to ,pichard1 accelerates the process more than any other substance known4 ,taking the effect of gypsum as the maximum1 he found that1 other things being equal1 the amounts of nitrates formed were as shown in the table below1 the effect of gypsum being taken as #ajj3 ,gypsum #ajj ,sodic ,sulfate #dg4i ,potassic ,sulfate #ce4h ,calcic ,carbonate #ac4c ,magnesic ,carbonate #ab4e ,the above estimates are markedly confirmed by the observations of the writer in the alkali soils of ,california4 ,in these1 nitrates exist most abundantly when the salts contained in the soil are mainly sulfates2 while wherever common salt or sodic carbonate are present in considerable amounts1 the amounts of nitrate found are notably less4 ,in saline seashore lands nitrates are usually present in traces only4 ,wollny has moreover shown that the nitrates themselves exert a repressive influence on nitrification4 ,effects of ,aeration and ,reduction4--,while the fostering effect of sulfates upon nitrification is very energetic in well aerated soils1 they become injurious whenever by a reductive process in ill-drained lands1 the sulfates are reduced to sulfids4 ,under such conditions the process will in any case be much impaired4 ,on the other hand1 the favoring effect of abundant aeration was strikingly shown in the experiment made by ,deherain1 in which a cubic meter of soil was left unmoved for several months1 while a similar mass was thoroughly agitated once a week during the same time4 ,the proportion of nitrates formed in the latter case was as #gj to #a formed in the quiescent soil mass4 ,it follows that the intensity of nitrification is essentially dependent upon the porosity of the soil2 and that it is thus greatly favored in the pervious soil-strata of the arid regions4 ,it also follows that thorough and frequent tillage and fallowing greatly favor nitrification2 thus explaining one of the beneficial results of these operations4 ,at the same time1 it is true that we may thus in a short time seriously diminish the reserve stock of nitrogen contained in the soil in the form of humus-amids2 and since nitrates are exceedingly liable to be lost from the soil in several ways1 such excessive nitrification is to be avoided4 ,unhumified ,organic ,matter does not ,nitrify4--,there can be little doubt that the formation of ammonia from the amido-compounds in humus is also the work of bacteria2 but this1 really the initial phase of the nitrogen-nutrition of plants1 has not yet been fully elucidated4 ,that1 however1 it is essentially only the ready-formed humus and not the unhumified debris of the soil which participate in nitrification was shown by the experiments of the writer1 see chapter #ai4 ,illustration3 ,,fig4 #ag4--;,bacillus denitrificans ,i4 7,burri47 ,denitrifying ,bacteria4--,among the sources of loss of nitrates in the soil is the action of denitrifying bacteria2 some of which cause merely the reduction of nitrates to nitrites and progressively to ammonia1 while others cause gaseous nitrogen to be given off from nitrites and nitrates1 resulting in their complete loss to the soil4 ,while there are probably several kinds of the latter class1 the most rapidly effective is an organism contained abundantly in fresh horse dung1 and also on the surface of old straw4 ,this can readily be shown by subjecting a very dilute solution 7#a-c per cent47 of ,chile saltpeter to the action of fresh horse dung in a close flask1 when nitrogen and carbonic dioxid gases are evolved1 and in a few days the nitrate has totally disappeared4 ,in the course of time this power of horse-manure disappears2 so that 8rotted manure0 is practically free from it and under proper conditions serves nitrification so effectively1 that in the past it has served extensively for the production of saltpeter in the 8niter-plantations0 for the industrial purposes2 the material of which was loose earth1 marl and manure1 kept moist and frequently forked over for better aeration4 ,saltpeter is similarly produced in stables1 corroding the mortar of brick foundations4 ,nevertheless1 it is necessary to avoid the use1 either together or at short intervals apart1 of ,chile saltpeter and fresh manure2 the manure if used first should be allowed to remain at least two months in the soil before saltpeter is applied4 ,the reduction of nitrates to nitrites and ammonia is brought about by quite a number of bacteria1 mostly anaerobic1 and such as consume combined oxygen in their development4 ,thus the butyric ferment1 which in the absence of readily reducible compounds evolves free hydrogen1 will in presence of nitrates reduce the latter to nitrites1 or form ammonia by addition of hydrogen to nitrogen just set free by reduction4 ,such reductive processes of course occur chiefly in soils rich in organic matter1 or ill-aerated4 ,the ammonia so formed1 while at first simply combining with any humus acids present1 may in the course of time be itself reduced to the amidic condition1 being thereby rendered relatively inert1 until again brought into action by ammonia-forming bacteria4 ,ammonia-forming ,bacteria4--,a large number of different bacteria appear to be concerned in the formation of ammonia from compounds of the albuminoid group1 7and probably from humus74 ,among these is one of the most common in soils 7,bacillus mycoides1 root bacillus71 which while forming ammonia carbonate in solutions of albumen1 is also capable of reducing nitrates to nitrites and ammonia in presence of a nutritive solution of sugar4 ,the 8hay bacillus0 7,b4 subtilis71 so abundantly developed in hay infusions1 and one of the most abundant in cultivated soils1 has together with ,b4 ellenbachensis1 ,b4 megatherium1 ,b4 mycoides1 and others1 by some been credited with important action in favoring vegetation2 so that a fairly pure culture of ,b4 ellenbachensis has been brought out commercially in ,germany under the name of 8,alinit40 ,rigorous culture experiments made by ,stutzer and others have1 however1 failed to show any general benefit from the use of alinit in infecting either land or seeds4 ,but there is no doubt of the ,effects of ,bacterial ,life on ,physical ,soil ,conditions4--,it is apparent that all conditions favoring the life of aerobic 7air-needing7 bacteria tend also to produce the loose1 porous state 7tilth7 of the surface soil so conducive to the welfare of culture plants1 designated by ,german agriculturists as 8,bodengare40 ,whether or not this condition is directly due to bacterial processes1 as is thought by ,stutzer 7,landw4 ,presse1 #aijd1 ,no4 #aa7 it is assuredly a highly important point to be gained1 and is essentially connected with the presence of humus in adequate amounts1 which is also a favoring condition of abundant bacterial life4 ,it seems that the preference given to the shallow putting-in1 or even surface application of stable manure1 existing in ,europe1 is largely based upon the marked effect upon the looseness of the surface soil1 generally credited to the physical effect of the manure substance itself1 but apparently largely due to the intensity of bacterial action thus brought about4 ,illustration3 ,,fig4 #ah4--;,bacillus subtilis4 7,wollny1 after ,brefeld47 ,illustration3 ,,fig4 #ai4--;,bacteria producing ammoniacal fermentation3 ,a1 ,c4 mycoides3 ,b1 ,b4 stutzeri4 7,from ,conn1 ,agr4 ,bacteriology47 ,illustration3 ,,fig4 #bj4--;,bacillus megaterium4 7,from ,migula47 ,,root-,,bacteria ,,or ,,rhizobia ,,of ,,legumes4--,among the most important bacteria1 agriculturally1 is that which enables plants of the leguminous order--7peas1 beans1 vetches1 clovers1 lupins1 etc471--to obtain their supply of nitrogen from the air independently of those contained in the soil4 ,the source of nitrogen to plants was long a disputed question2 it was at first supposed 7by de ,saussure7 that it was obtained directly from the soil by the absorption of humus2 but this was disproved1 and ,liebig then contended that it was derived directly from the atmosphere through the ammonia in rain water4 ,this was then shown to be wholly inadequate2 and ,boussingault proved conclusively that plants do not take up nitrogen gas from the air4 ,this was subsequently denied by ,ville2 but investigation at the ,rothamstead agricultural station by ,lawes and ,gilbert definitely confirmed ,boussingault's results4 ,at the same time they also proved very definitely that while grass and root crops deplete the soil of nitrogen1 clover and other leguminous crops leave in the soil more nitrogen than was previously present1 even when the entire1 itself highly nitrogenous1 leguminous crop is removed from the land4 ,the improvement of lands for wheat production by rotation with clover had long ago become a practical maxim2 but the cause was not understood until1 in #ahhh1 ,hellriegel and ,wilfarth announced that the variously-shaped excrescences or tubercles which had long been observed as frequently deforming the roots of legumes1 are caused by the attacks of bacilli capable of absorbing the free nitrogen of the air and thus enabling the host-plant to acquire its needed supply by absorbing the richly nitrogenous matter thus accumulated in the excrescences4 ,the minute rod-shaped organism was named ,bacillus radicicola by ,beyerinck2 ,rhizobium leguminosarum1 by ,a4 ,frank1 who has published an extensive treatise on the subject4#eg ,illustration3 ,,fig4 #ba4--,microscopic section of cell tissue1 from a nodule of ,square-pod pea1 showing cells filled with ,rhizobia4#eh #eg ,uber die ,pilzsymbcose der ,leguminosen1 ,berlin1 #ahij4 #eh ,original figure from drawing by ,o4 ,butler1 ,asst4 in ,agr4 ,dep't ,univ4 of ,california4 ,microscopic examination of the nodules shows their tissues to contain partly motile1 free bacteria1 partly others 7bacteroids71 which have assumed a quiescent condition1 and are of much greater dimensions than those of the motile form4 ,these relatively thick1 and sometimes forked1 forms1 differing somewhat in each of the group adaptations mentioned below1 constitute the bulk of the cell-contents of the nodules1 and ultimately serve for the nutrition of the host-plant with nitrogen4 ,when the growth of the excrescence is completed1 the swollen1 quiescent bacteroids gradually collapse and become depleted of their nitrogenous substance2 and finally the apparently empty husk remains or drops off1 carrying with it the minute cocci which in the soil become active bacteria again4 ,the nodules are thus found mainly on the actively-growing roots1 and at the time when vegetation and assimilation are most active in the plant4 ,in autumn1 or when the plants are in fruit1 the roots may be wholly destitute of nodules4 ,illustration3 ,,fig4 #be4--,square-pod pea4--,tetragonolobus purpureus4 ,,fig4 #bf4--,white ,lupin4--,lupinus albus4 ,the adhesion of the nodules to the roots is mostly very loose1 and their falling-off when the seedlings are carelessly transplanted1 doubtless accounts for much of the difficulty generally found in transplanting legumes when once established4 ,the figures annexed show the various forms assumed by the nodules in different plants1 and with them also the corresponding forms of the bacteroids of each4 ,the latter1 here shown magnified about #ajjj times1 are taken from the inaugural dissertation of ,d4 ,brock on this subject1 published at ,leipzig in #ahia4 ,it appears that the forms of the bacteroids are quite as much varied as are those of the nodules they form4 ,illustration3 ,,fig4 #bb4--;,common ,vetch4--,vicia sativa4 ,,fig4 #bc4--;,bur clover4--,medicago denticulata4 ,,fig4 #bd4--;,garden pea4--,pisum sativum4 ,varieties of ,forms4--,while these bacilli seem to be normally present in most soils1 it seems to be necessary that they should adapt themselves for this symbiosis#ei with each of several groups of the legumes in order to exert their most beneficial effects4 ,in many soils there appears to exist a 8neutral form01 which requires about a season's time or more to adapt itself specially to the several leguminous groups so that a great advantage is gained by infecting either the seeds or the soil with the forms already adapted1 when no similar plant has lately occupied the same ground4 ,thus the bacillus of the clover root is of little or no benefit to beans1 peas or alfalfa1 and the root-bacilli of each of the latter are relatively ineffectual when used to infect either of the other groups4 ,the same is true of the bacilli of lupins and of acacias1 as applied to leguminous plants of any other groups4#fj #ei 8,living together0 beneficially2 in contradistinction to parasitism1 which is injurious to the host plant4 #fj ,it is asserted by some observers that the root-bacilli producing differently-shaped excrescences upon different legumes are distinct species2 but this view is not sustained by the experiments of ,nobbe and ,hiltner1 and seems intrinsically improbable4 ,mode of ,infection4--,the infection is especially effectual when applied to the seeds before sowing2 and for that purpose there may be used either the turbid water made by stirring up in it some earth of a properly infected field1 or else water charged with a pure culture of the appropriate kind1 commercially known under the name of nitragin1 now manufactured for the purpose4 ,or else1 the field to be sown may be infected by spreading on it broadcast1 and promptly harrowing in1 a wagon-load of earth per acre from a properly infected field4 ,such earth must not be allowed to dry1 or to be long exposed to light4 ,specially effective 78virulent07 and hardy forms of such bacteria have been produced under artificial culture by ,dr4 ,geo4 ,t4 ,moore of the ,u4,s4 ,department of ,agriculture4 ,these cultures can be sent by mail on cotton imbued with them1 for the infection of seeds4 ,it is very important that the bacillus should be present in the earliest stages of the growth of the seedlings2 otherwise the latter will undergo a longer or shorter period of starvation1 unless the soil contains1 or is furnished with1 a sufficiency of available nitrogen to supply their immediate wants4 ,when such a supply is very abundant1 the legume crop will sometimes develop no nodules at all2 but the best crops appear to be the result of a thorough infection1 and abundant formation of the excrescences4 ,cultural ,results4--,the marked results obtained in certain soils by inoculation with the legume-root bacillus are exemplified in the following table1 showing results of experiments by ,j4 ,f4 ,duggar1 at the ,alabama ,experiment station4#fa ,,table ,,showing ,,increase ,,of ,,production ,,by ,,soil ,,inoculation4 ,,per ,,acre4 ,,tops4 ,,roots4 ,,nitrogen4 lbs4 lbs4 lbs4 ,value4 ---------------------------------------- -------------------- ,hairy vetch1 not inoculated #aid #chg #g #a4je 8 8 inoculated #cjde #adeb #ajf #ae4ij ,crimson clover not inoculated #ajf #bff #d4c 4#fe 8 8 inoculated #dhdj #adeb #adc4g #ba4be ---------------------------------------- -------------------- #fa ,bull4 ,ala4 ,exp't ,station1 ,no4 #if1 #ahih4 ,such marked increases from soil inoculation cannot of course be expected in cases where the soil has previously borne leguminous crops of similar nature and therefore already contains the root bacteria4 ,hence ,duggar found no increase of production when inoculating for cowpea1 land that had borne that crop two years before and already contained the root bacteria4 ,in the arid region1 where the almost universally calcareous soils usually bear a natural growth largely composed of various leguminous plants1 inoculation is likely to be less commonly effective than in the humid region east of the ,mississippi1 where leguminous plants are much less generally present in the native flora4 ,the distinctive agricultural function of supplying nitrogen to the soils on which they grow1 renders inexcusable the persistence of some writers and teachers in designating all forage plants as 8grasses40 ,whatever excuse there may have been for this practice so long as the nitrogen-gathering function of the legumes was unknown1 disappears with this discovery1 and the misleading misnomer should be banished from agricultural publications and lectures1 at the very least4 ,other ,nitrogen-,absorbing ,bacteria4--,an increase in the nitrogen-content of some soils1 aside from the action of leguminous root-bacteria1 has long been observed4 ,as already stated1 this increase was at first ascribed to certain green alg often seen to develop on the soil surface2 but it has now been shown that the nitrogen-gathering function belongs to at least two bacteria1 one of which 7,clostridium pastorianum7 was discovered by ,winogradski1 the other 7,azotobacter chroococcum7 by ,beyerinck1 and has since been farther investigated by ,koch1 ,krber1 ,gerlach and ,vogel1 and last by ,lipman and ,hugo ,fischer4 ,according to the latter it seems likely that ,azotobacter chroococcum lives in symbiosis with the green alg1 all of which1 like the ,azotobacter itself1 develop with special luxuriance on calcareous soils4 ,lipman 7,rep4 ,agr4 ,exp't ,station1 ,new ,jersey1 #aijc and #aijd7 describes as ,azotobacter vinelandii a form somewhat different from the ,a4 chroococcum1 the nitrogen-assimilating power of which he tested quite elaborately4 ,he exposed to air pure cultures of ,a4 vinelandii in nutritive solution containing the proper mineral ingredients1 and glucose #bj grams per liter4 #ajj cub4 centimeters of this solution was exposed in flasks of respectively #bej1 #ejj and #ajjj cc4 content1 therefore having greater surface in the larger flasks4 ,after ten days1 the amounts of nitrogen fixed were found to be respectively #a4fg1 #c4ai and #g4ij milligrams4 ,when mannite solution was employed instead of glucose1 a similar fixation was observed2 and it was also shown that the presence of combined nitrogen in the forms of nitrates or ammonium salts discouraged the fixation by the bacillus4 ,it was thus clearly proved that ,a4 vinelandii at least does not need symbiosis with alg to fix atmospheric nitrogen2 but experiments with mixed cultures of the above bacillus and another 7designated as ,no4 #cj by ,lipman7 proved that when these two co-operate the absorption of atmospheric nitrogen is nearly doubled4 ,as it is probable that this is the case also with other soil bacteria1 the importance of this source of nitrogen to plants is obvious2 provided of course that the proper nutritive ingredients are present in available form4 ,lipman shows that among the organic nutrients1 besides the sugars1 glycerine and the salts of propionic and lactic acids1 and probably also others of the same groups1 can serve as nourishment to the nitrogen-fixing bacteria4 ,,distribution ,,of ,,the ,,humus ,,within ,,the ,,surface ,,soil4 ,the uniform distribution of the humus-contents of the surface soil1 as shown in sections of the same1 is by no means easily accounted for4 ,the roots from which its substance is so largely derived are not so universally distributed as to account for it2 but least of all can the rapid disappearance of the leaf-fall and other vegetable offal from the surface be accounted for without some outside agencies4 ,of these1 the action of fungous vegetation1 and of insects and earthworms1 are doubtless the chief ones4 ,fungi4--,when we examine a decaying root1 we find radiating from it a zone of deeper tint1 as though from a colored solution penetrating outward4 ,but since under normal conditions humus is insoluble1 this explanation cannot stand4 ,microscopic examination1 however1 reveals that the outside limit of this zone is also the limit to which the fungous fibrils concerned in the process extend2 and as these fibrils are much more finely distributed and much more numerous than the roots of any plant1 it is natural that the humus resulting from their decomposition should be more evenly distributed than the roots themselves4#fb #fb ,kosticheff1 ,formation and ,properties of ,humus2 in abstract ,jour4 ,chem4 ,soc41 #ahia1 p4 #faa4 ,such fungous growth is not1 however1 confined to dead and decaying roots only4 ,a large number of trees and shrubs1 among them pines and firs1 beeches1 aspen and many others1 also the heaths1 and woody plants associated with them1 appear to depend largely for their healthy development1 notably in northern latitudes1 upon the co-operation 78symbiosis07 of fungous fibrils that 8infest0 their roots1 enabling them to assimilate1 indirectly1 the decaying organic 7and inorganic7 matter which would otherwise be unavailable1 and at the same time converting that matter into their own substance4 ,fungous growths thus mediate both the decomposition and rehabilitation of the vegetable debris4 ,the vegetative fibrils 7mycelia7 of several kinds of molds are constantly present in the soil1 and while consuming the dead tissue of the higher plants1 spread their own substance throughout the soil mass4 ,the same is true of the subterranean or 8root0 mycelia of the larger fungi1 toadstools1 mushrooms1 which are commonly found about dead stumps and other deposits of decaying vegetable and animal offal4 ,all these being dependent upon the presence of air for their life functions1 remain within such distance from the surface as will afford adequate aeration2 the depth reached depending upon the perviousness of the soil and subsoil4 ,in the humid region this will usually be within a foot of the surface1 but in the arid may reach to several feet4 ,ultimately these organisms contribute their substance to the store of humus in the land4 ,on the surface of moist soils we frequently find a copious growth of green fibrils1 which may be either those of alg1 such as ,oscillaria1 or the early stages 7prothallia7 of moss vegetation4 ,this vegetation has been credited with absorption of nitrogen from the air1 thus enriching the soil2 but later researches have shown this effect to be due to symbiotic bacteria 7see above p4 #aef74 ,animal ,agencies4--,darwin first suggested that wherever the common earthworm 7,lumbricus7 finds the conditions of existence1 it exerts a most important influence in the formation of the humous surface-soil layer2 and the limitation imposed upon these conditions by the subsoil has doubtless a great deal to do with the sharp demarcation we often find between it and the surface soil4 ,briefly stated1 the earthworm nourishes itself by swallowing1 successively1 portions of the surrounding earth1 digesting a part of its organic matter and then ejecting the undigested earth in the form of 8casts10 such as may be seen by thousands on the surface of the ground during or after a rain4 ,darwin 7,the ,formation of ,vegetable ,mold1 #ahha71 has calculated from actual observation that in humid climates and in a ground fairly stocked with these worms1 the soil thus brought up may amount to from one-tenth to two-tenths of an inch annually over the entire surface2 so that in half a century the entire surface foot might have been thus worked over4 ,aside from the mechanical effect thus achieved in loosening the soil1 and the access of air and water permitted by their burrows1 the chemical effects resulting from their digestive process1 and the final return of their own substance to the soil mass2 also their habit of drawing after themselves into their burrows leafstalks1 blades of grass and other vegetable remains1 renders their work of no mean importance both from the physical and chemical point of view4 ,the uniformity1 lack of structure and loose texture of the surface soil1 especially of forests1 as compared with subsoil layers of corresponding thickness1 is doubtless largely due to the earthworms' work4 ,it has frequently been observed that when an unusual overflow has drowned out the earthworm population of a considerable area1 the surface soil layer remains compacted1 and vegetation languishes1 until new immigration has restocked the soil with them4 ,again1 the humus formed under their influence is always neutral1 never acid4 ,wollny 7,forsch1 ,agr41 #ahij1 p4 #chb71 has shown by direct experimental cultures in boxes1 with and without earthworms1 surprising differences between the cultural results obtained1 and this has been fully confirmed by the subsequent researches of ,djemil 7,ber4 ,physiol4 ,lab4 ,vers4 ,halle1 #ahih74 ,in ,wollny's experiments1 the ratio of higher production in the presence of the worms1 varied all the way from #b4f per cent in the case of oats1 #ic4i in that of rye1 #ace4i in that of potatoes1 #cjj in that of the field pea1 and #adj in that of the vetch1 to #gcc per cent in the case of rape4 ,wollny attributes these favorable effects in the main to the increased looseness1 and perviousness of the soil to air1 and diminished water-holding power4 ,djemil's results all point in the same direction2 and he shows1 moreover1 that the allegation that the roots penetrate more deeply in the presence of the worms by following their burrows1 is unfounded1 the descending roots often passing close to and outside of these4 ,the work of earthworms is especially effective in loamy soils and in the humid regions4 ,in the arid region1 and in sandy soils generally1 the life-conditions are unfavorable to the worm1 and the perviousness elsewhere brought about by its labors already exists naturally in most cases4 ,it is stated by ,e4 ,t4 ,seton 7,century ,mag4 for ,june1 #aijd7 that the earthworm is practically non-existent in the arid region between the ,rocky ,mountains and the immediate ,pacific coast1 from ,manitoba to ,texas4 ,in the ,pacific coast region1 however1 they are abundant1 and do their work effectually4 ,insects of various kinds are also instrumental in producing1 not only the uniform distribution of humus in the surface soil1 but also the looseness of texture which we see in forest soils especially4 ,ants1 wasps1 many kinds of beetles1 crickets1 and particularly the larv of these1 and of other burrowing creatures1 often form considerable accumulations1 due directly both to their mechanical activity1 and to their excrements4 ,the work of ants is in some regions on so large a scale as to attract the attention of the most casual observer4 ,especially is this the case in portions of the arid region1 from ,texas to ,montana1 where at times large areas are so thickly studded with hills from three to twelve feet in diameter1 and one to two feet high1 that it is difficult to pass without being attacked by the insects4 ,the 8mounds0 studding a large portion of the prairie country of ,louisiana seem also to be due to the work of ants1 although not inhabited at present4 ,larger burrowing animals also assist in the task of mixing uniformly the surface soils1 and aiding root-penetration1 as well as1 in many cases1 the conservation of moisture4 ,seton 7loc4 cit47 even claims that the pocket gophers 7,thomomys7 in a great degree replace the activity of the earthworms in the arid region1 where they1 together with the voles 7commonly known there as field mice71 exist in great numbers4 ,of course the work of these animals1 as well as that of the prairie dogs1 ground squirrels1 badgers1 etc41 is incompatible with cultivation4 ,but the effects of their burrows on the native vegetation1 and the indications they give of the nature of the subsoil1 are eminently useful to the land-seeker4 ,thus in the rolling sediment-lands of the ,great ,bend of the ,columbia1 the observer is surprised to see the 8giant rye grass10 usually at home in the moist lowlands1 growing preferably on the crests of the ridges bordering the horizon4 ,examination shows that this is due to the burrowing of badgers1 whereby the roots of the grass are enabled to reach moisture at all times1 even in that extremely arid region4 ,,chapter ,x4 ,,soil ,,and ,,subsoil 7,continued7 ,,their ,,relations ,,to ,,vegetation4 ,physical ,effects of the ,percolation of ,surface ,waters4--,the muddy water formed by the beating of rains on the soil surface will1 in penetrating the soil1 carry with it the diffused colloidal clay to a certain depth into the subsoil4 ,we should therefore expect that as a rule every subsoil will be more clayey than its surface soil2 and this is found to be almost universally the case in the humid region4 ,subsoils are therefore almost always less precious and more retentive of moisture1 as well as of plant-food substances in solution1 than their surface soils1 unless these are very rich in humus2 and as the finest particles are usually those richest in available plant-food1 it follows that subsoils will as a rule be found to contain larger supplies of the latter than the surface soil4 ,common experience as well as comparative analysis confirm both of these inferences so thoroughly1 that it becomes unnecessary to adduce examples in this place4 ,on the other hand1 the reverse1 upward movement of moisture caused by surface evaporation tends constantly to bring any soluble salts contained in the soil mass nearer to the surface1 thus increasing the stock of easily available plant-food in the surface soil4 ,in extreme cases1 especially in the arid region1 this accumulation of salts may become excessive1 and seriously injurious to plant growth4 7,see 8,alkali ,soils01 chapters #ba1 #bb47 ,chemical effects of ,water-,percolation4--,the accumulation of plant-food in the subsoil is not1 however1 due only to the mechanically-carried particles1 but also to the ingredients carried in solution from the surface soil and redeposited in the more retentive subsoils4 ,especially is this true of lime carbonate1 which is dissolved by the carbonic acid formed chiefly within the humic surface soil1 and is often carried off in amounts sufficient to obstruct drain tiles by its deposition in contact with air 7see chapt4 #c74 ,in the case of moderate rains1 however1 it is carried no farther than the subsoil1 and is there redeposited1 in consequence of the penetration of air1 following the water1 and causing the carbonic gas to diffuse upward2 thus leaving the lime carbonate behind4 ,in the majority of cases this results simply in a gradual enriching of the subsoil in this substance2 while the surface soil may become so depleted as to require its artificial replacement by liming or marling4 ,the same general process occurs to a less extent1 in the case of magnesia4 ,calcareous ,subsoils4--,the fact that subsoils are more calcareous than the corresponding surface soils is often of great practical importance1 in enabling the farmer to enrich his depleted surface soil in lime by subsoil plowing4 ,the accumulation of lime carbonate in the subsoil also tends in a measure to offset the extreme heaviness sometimes resulting from the accumulation of clay4 ,calcareous ,subsoils and ,hardpans4--,when soils are very rich in lime1 and rains occur in limited showers rather than continuously1 the lime carbonate dissolved from the surface soil may accumulate in the subsoil so as to either form calcareous 8hardpan0 by the cementing of the subsoil mass2 or it may accumulate and partly crystallize around certain centers and thus form white concretions1 known to farmers as 8white gravel40 ,the latter is the form usually assumed in the regions of summer rains2 while in the arid regions the deficient rainfall causes this substance to accumulate1 and calcareous hardpan to form1 at definite depths depending upon the maximum penetration of the annual rainfall2 sometimes in crystalline masses of veritable limestone 78kankar0 of ,india71 or sometimes merely as crystalline incrustations loosely cementing the subsoil4 8,rawness0 of ,subsoils in ,humid ,climates4--,from the greater compactness of the subsoil which is almost universal in the humid regions1 the absence of humus and of the resulting formation of carbonic and humic acids1 it follows that its minerals are less subject to the weathering process than are those of the surface soil4 ,in the farmer's parlance1 the subsoil is 8raw0 as compared with the surface soil2 it is not so suitable for plant-nutrition1 and therefore must not be brought to the surface to form the seed-bed1 or be incorporated with the surface soil to any considerable extent at any one time1 if crop-nutrition is to be normal4 ,it is only in the course of time1 by exposure to atmospheric action as well as to that of the humus1 and of plant roots1 that it becomes properly adapted to perform the functions of the surface soil4 ,soils and ,subsoils in the ,arid ,region4--,but however pronounced and important are these distinctions and differences in the humid region1 they are found to be profoundly modified in the arid2 where1 as before stated1 the formation of colloidal clay is very much diminished1 so that most soils formed under arid conditions are of a sandy or pulverulent type4 ,there is then little or no clay to be washed down into the subsoil1 hence there is no compacting of the latter2 the air consequently circulates freely down to the depth of many feet4 ,thus one of the most important distinctions between soil and subsoil is to a great extent practically non-existent in the arid region1 at least within the depths to which tillage can be made to reach2 so that the limitations attached to subsoil-plowing in the countries of summer rains do not apply to the characteristic soils of the arid regions4 ,even the distinction in regard to humus is here largely obliterated by the circumstance1 already alluded to1 that most of that substance must1 in the arid regions1 be derived from the decay of roots1 which moreover reach to much greater depth in these soils4 ,hence even in the uplands of the arid region it is common to find no change of tint from the surface down to three feet1 and even more4 ,this1 like the free circulation of the air in consequence of porosity1 tends to render the distinction of soil and subsoil practically useless2 since it disposes of the objection to 8subsoiling0 based upon the inert condition of the subsoil1 which in humid climates so effectually interferes with the welfare of crops unless subsoiling is restricted to a fraction of an inch at a time4 ,these fundamental differences in the soils of the two regions are illustrated schematically in the subjoined diagram1 which shows on the left the contrast between clay or clay loam soils1 in which the depth of the surface soil-sample to be taken is prescribed as nine inches by the rules of the ,association of ,am4 ,official ,chemists 7in the writer's experience it is more nearly six inches as a rule74 ,alongside of the ,eastern soil thus characterized is placed a typical 8adobe0 soil from the grounds of the ,california ,experiment station1 of which a sample showing uniform blackness to three feet depth was exhibited at the ,world's ,fair at ,chicago in #ahic4 ,at the right is a profile of the noted hop soil on the bench lands of the ,russian river1 ,cal41 in which the humus-content was determined down to twelve feet1 the humus-percentage being 4#dd at that depth against #a4ba in the surface foot 7see chapt4 #h1 p4 #aci74 ,in this and similar soils the roots of hops reach down to as much as fourteen feet without much lateral expansion2 as shown in plate ,no4 #ca of this chapter4 ,similar conditions prevail in the sandy uplands1 as1 e4 g41 in the wheat lands of ,stanislaus county1 ,cal41 mentioned above4 ,taking the clay soils as a fair type for comparison1 it would seem that the farmer in the arid region owns from three to four farms1 one above another1 as compared with the same acreage in the ,eastern states4 ,subsoils and ,deep-plowing in the ,arid ,region4--,up to the present time this advantage is but little appreciated and acted upon by the farmers of the arid region4 ,they still instinctively cling to the practice taught them by their fathers1 and which is still promulgated as the only correct practice1 in most books on agriculture4 ,there are of course in the arid as well as in the humid region1 cases in which deep plowing is inadvisable2 viz1 that of marsh or swamp lands1 as well as sometimes in very sandy1 porous soils1 the cultural value of which often depends essentially upon the presence of a somewhat consolidated1 and more retentive subsoil1 which should not be broken up4 ,but in most soils not of extreme physical character1 it is in the arid region not only permissible1 but eminently advisable to plow1 for preparation1 as deeply as circumstances permit1 in order to facilitate the penetration of the roots beyond the reach of harm from the summer's drought2 while for the same reason1 subsequent cultivation should be to a moderate depth only1 for the better conservation of moisture1 and the formation of a protective surface mulch 7see chapter #ac74 ,illustration3 ,,type ,,of ,,eastern ,,soils ,,types ,,of ,,california ,,soils4 ---------------------------------------- --------------- ,ft4 ,upland4 ,up land clay-loam4 ,beach land4 ---------------------------------------- --------------- ,,fig4 #bg4--,soil ,profiles illustrating differences in ,soils of ,humid and ,arid ,region4 ,it must not be forgotten that there are in the lowlands of the arid region 7river swamps or tules1 sea-coast marshes1 etc417 soils in which surface soil and subsoil are differentiated as fully as in the humid countries2 at least so long as they have not been fully drained for a considerable length of time4 ,in swamp areas that have been elevated above the reach of overflow or shallow bottom-water by geological agencies1 even the heavy swamp clays are fully aerated down to great depths1 and roots penetrate accordingly4 ,examples of ,plant-growth on ,arid ,subsoils4--,the fact that in the arid region the surface-soil conditions reach to so much greater depths than in the ,east and in ,europe1 is so important for farming practice in that region that experimental evidence of the same should not be withheld4 ,of such1 some cases well established as typical of ,california experience are therefore cited4 ,it is well known that in the ,sierra ,nevada of ,california the placer mines of the ,foothills1 worked in the early times1 have long disappeared from sight1 having been quickly covered by a growth of the bull pine 7,p4 ponderosa74 ,much of this timber growth has for a number of years past been of sufficient size to be used for timbering in mines1 and a second young forest is springing up on what was originally the red earth of the placer mines1 which appears to the eye as hopelessly barren as the sands of the desert4 ,in this same red sandy earth not unfrequently cellars and house foundations are dug1 and the material removed1 even to the depth of eight feet1 is fearlessly put on the garden and there serves as a new soil1 on which vegetables and small fruits grow1 the first year1 as well as ever4 ,in preparing such land for irrigation by leveling or terracing no heed is taken of the surface soil as against the subsoil1 even where the latter must be removed to the depth of several feet1 so long as a sufficient depth of soil material remains above the bedrock4 ,the same is generally true of the benchlands2 the irrigator levels1 slopes or terraces his land for irrigation with no thought of discrimination between soil and subsoil1 and the cultural result as a rule justifies his apparent carelessness4 ,it is only where from special causes a consolidated or hardpan subsoil is brought to the surface1 that the land when leveled shows 8spotted0 crops4 ,such is the case in some of the 8hog-wallow0 areas of the ,san ,joaquin valley of ,california1 and in some cases where by long cultivation and plowing to the same depth1 a compact soil-layer or plowsole has been formed1 and the land is then leveled for the introduction of irrigation4 ,in these cases a section of the soil mass will usually show a marked difference in color and texture4 ,but1 as a rule1 in taking soil samples1 no noticeable difference can be perceived between the first and the second1 and oftentimes as far down as the third and fourth foot4 ,the extraordinary root-penetration of trees1 shrubs and taprooted herbs1 whose fibrous feeding-roots are found deep in the subsoil and are sometimes wholly absent from the surface soil1 fully corroborate the conclusion reached by the eye4 ,the roots of grape vines have been found by the writer at the depth of twenty-two feet below the surface1 in a gravelly clay loam varying but little the entire distance4 ,in a similarly uniform and pervious material1 the loess of ,nebraska1 ,aughey#fc reports the roots of the native ,shepherdia to have been found at the depth of fifty feet4 #fc ,see ,merrill1 ,rocks and ,rock weathering4 ,resistance to ,drought4--,these peculiarities of the soils of the arid region explain without any resort to violent hypotheses1 the fact that many culture plants which in the regions of summer rains are found to be dependent upon frequent and abundant rainfall1 will in ,california1 and in the country west of the ,rocky ,mountains generally1 thrive and complete their growth and fruiting during periods of four to six months of practically absolute cessation of rainfall2 when east of the ,mississippi a similar cessation for as many weeks will ruin the crops1 if not kill the plants4 ,in continental ,europe1 in #ahib1 a six weeks' drought caused almost all the fruit crops to drop from the trees1 and many trees failed to revive the next season2 while at the very same time1 the same deciduous fruits gave a bountiful crop in ,california1 during the prevalence of the usual five or six months' drought4 ,this was without irrigation1 or any aid beyond careful and thorough surface tillage following the cessation of rains in ,april or ,may1 so as to leave the soil to the depth of five or six inches in a condition of looseness perfectly adapted to the prevention of evaporation from the moist subsoil1 and of the conduction of the excessive heat of the summer sun4 ,this surface mulch will contain practically no feeding-roots1 the paralysis or death of which by heat and drought would influence sensibly the welfare of the growing plant4 ,illustration3 ,,fig4 #bh4--,root of an ,eastern 7,wisconsin7 ,fruit ,tree4 7,photograph by ,prof ,f4 ,h4 ,king47 ,root-system in the ,humid ,region4--,it is quite otherwise where a dense subsoil not only obstructs mechanically the deep penetration of any but the strongest roots1 but at the same time is itself too inert to provide sufficiently abundant nourishment apart from the surface soil1 which is there the portion containing1 alongside of humus1 the bulk of the available plant-food1 and in which alone the processes of absorption and nutrition find the proper conditions2 such as access of air and the ready and minute penetration of even the most delicate rootlets and root-hairs4 ,the largest and most active portion of the root-system being thus accumulated in the surface soil1 it follows that unless the latter is constantly kept in a fair condition of moistness1 the plant must suffer material injury very quickly2 hence the often fatal effects of even a few weeks' drought4 ,the same occurs in the arid region when often-repeated shallow plowing has resulted in the formation of a 8plowsole0 which prevents the deep penetration of roots2 when a hot 8norther0 will often in a short time not only dry the plowed soil1 but will heat it to such extent as to actually bake the roots it harbors4 ,under the same weather-conditions an adjoining field1 properly plowed1 may almost wholly escape injury4 ,illustration3 ,,fig4 #bi4--,prune ,tree on ,peach ,root1 at ,niles1 ,cal4 ,comparison of root development in the arid and humid regions4--,figures #bh1 #bi given here show the differences as actually seen in the case of fruit trees as grown in ,wisconsin and ,california1 respectively1 both in the absence of artificial water-supply4 ,adaptation of humid species to arid conditions4--,figures1 in ,no4 #cj1 show the root systems respectively of the riverside grape 7,vitis riparia7 as grown in the ,mississippi ,valley states1 and the natural development as found in the ,rock grape of ,missouri and also in the wild grape vine of ,california4 ,it will be noted at once that the latter directs its cord-like roots almost vertically from the first1 until it reaches a depth varying from #ab to #ah inches1 where it begins to branch more freely1 but still with a strong downward tendency in all4 ,the roots of the riverside grape1 on the contrary1 tend to spread almost horizontally1 branching freely at the depth of a few inches and manifestly deriving its supply both of plant-food and moisture mainly from the surface soil4 ,it is curious to observe the behavior of this vine when cuttings are planted in ,california vineyards as a resistant grafting-stock4 ,its first roots are sent out horizontally1 very much as is its habit in the ,east1 so long as the soil moisture is maintained near the surface4 ,but as the season advances1 the more superficial rootlets are first thrown out of action by the advancing dryness and heat of the surface soil1 and many finally die the first year4 ,illustration3 ,,fig4 #cj4--,root ,growth of ,resistant ,grape ,vines4 ,not unfrequently the entire root system developed by the uppermost bud perishes2 but usually its main roots soon begin to recede from the threatening drought and heat of the surface1 curving1 or branching downward in the direction of the moisture supply1 and without detriment to their nutrition because of the practical identity of the surface soil and subsoil4 ,as the portions of the roots near the surface thicken and mature1 their corky rind soon prevents their being injured by the arid conditions to which they are subjected2 while the root-ends1 finding congenial conditions of nutriment and aeration in the moist depths1 develop without difficulty as they would in their humid home4 ,practically the same process of adaptation takes place in every one of the trees1 shrubs1 or perennials belonging to the humid climates1 until their root system has assumed nearly the habit of the corresponding native vegetation4 ,the photograph of the roots of a hop plant1 grown on bench lands of the ,sacramento river1 shows the roots extending to #h feet depth1 but where broken off the main root is still nearly two millimeters in thickness1 proving that it penetrated at least two feet beyond the depth shown in figure #ca4 ,in the case of native annuals1 either the duration of their vegetation is extremely short1 ending with or shortly after the cessation of rains2 or else their tap roots descend so low1 and the nutritive rootlets are developed at such depth1 as to be beyond reach of the summer's heat and drought4 ,for while it is true that rootlets immersed in air-dry soil may absorb plant-food1 this absorption is very slow and can only be auxiliary to the main root system which1 instead of terminating in the surface soil as in the humid region1 will be found to begin to branch off at depths of #ae and #ah inches1 and may then in sandy lands descend to from #d to #g feet even in the case of annual fibrous-rooted plants like wheat and barley4#fd ,in the case of maize the roots of a late-planted crop may sometimes be found descending along the walls of the sun-cracks in heavy clay land poorly cultivated2 and it frequently matures a crop without the aid of a single shower after planting4 ,see figures #cc1 #cd4 #fd ,shaler 7,origin and ,nature of ,soils2 #abth ,rept4 ,u4 ,s4 ,geol4 ,survey1 p4 #caa7 says3 8,annual plants cannot in their brief period of growth push their roots more than six to twelve inches below their root-crowns0--a generalization measurably true for the humid region only4 ,according to ,f4 ,j4 ,alway1 the roots of cereals penetrate to #e-g feet in ,saskatchewan1 also4 ,illustration3 ,,fig4 #ca4--;,hop ,root from ,sacramento ,bench-land4 ,the annexed plate 7,no4 #cb7 shows the main roots of two native perennial weeds of ,california1 the goosefoot 7,chenopodium californicum7 and the figwort 7,scrophularia californica71 common on the lower slopes of the coast ranges4 ,the soil was a heavy clay loam or 8black adobe0 resulting from the weathering of the clay shale bedrock1 fragments of which are so abundantly intermixed with the substrata that excavation of the roots became very difficult4 ,yet the main root of the goosefoot went down below the depth of eleven feet4 ,the main root of the figwort1 also1 was followed below the depth of ten feet without reaching the extreme end4 ,this proves clearly that the great penetration of the goosefoot was not1 as might be supposed1 due to its bulbous root4 ,yet such thickening of the root just below the crown is a rather common feature in arid-region plants1 and can here be noted even in the figwort1 within whose botanical relationship bulbous roots are almost unknown4 ,any one accustomed to the cornfields of the ,middle ,west1 where in the after-cultivation of maize it is necessary to restrict very carefully the depth of tillage to avoid bringing up a mat of white1 fibrous roots1 will be at once impressed with the remarkable adaptability of maize to different climatic conditions1 as exhibited in such cases and shown in figures #cc1 #cd4 ,in southern ,california1 in the deep mesa or bench soils1 corn stalks so tall that a man standing on horseback can barely reach the tassel1 and with two or three large ears1 are quite commonly grown under similar rainfall-conditions4 ,importance of proper ,substrata in the ,arid ,region4--,the paramount need of deep penetration of roots in the arid region renders the substrata below the range of what is usually understood by subsoil in the humid climates1 of exceptional importance4 ,a good farmer anywhere will examine the subsoil to the depth of two feet before investing in land2 but more than this is necessary in the arid region1 where the surface soil is often almost thrown out of action during the greater part of the growing season1 while the needful moisture and nourishment must be wholly drawn from the subsoil and substrata2 an examination of which should therefore precede every purchase of land1 or planting of crops4 ,illustration3 ,,fig4 #cb4--;,deep-,rooting of ,native ,california ,goosefoot and ,figwort4 ,illustration3 ,,fig4 #cc4--,kentucky ,maize1 grown in region of ,summer ,rains4 7,photography by ,a4 ,m4 ,peter47 ,illustration3 ,,fig4 #cd4--;,california ,maize1 ,grown ,without ,rain or ,irrigation4 ,such examinations are most quickly made by means of a probe consisting of a pointed1 square steel rod five or six feet long1 provided at one end with a loop for the insertion of a cross-handle like that of a carpenter's auger4 ,the handle being grasped with both hands1 the probe is forced into the soil with a slight reciprocating motion1 by the weight of the operator2 who soon learns how to interpret the varying kinds of resistance1 and on withdrawing the probe carefully will generally be able to determine if bottom water has been reached4 ,should this easy method of examination not convey all the needful information1 the post-hole auger may be resorted to2 and it is desirable that extra 7three-foot7 rods or gaspipe joints be provided for the purpose of lengthening the probe or auger1 when necessary1 to nine or twelve feet4 ,it will rarely be necessary to go to the trouble of digging a pit for such examinations2 but even this is to be recommended rather than 8buying a cat in a bag0 in the guise of an unexplored subsoil4 ,faulty ,substrata4--,a number of examples of 8faulty lands10 i4 e41 such as are underlaid by faulty substrata1 are given in the annexed diagram ,fig4 #ce2 the examples being taken from ,california localities because of their having been most thoroughly investigated4 ,similar cases1 as well as others not here illustrated1 of course occur more or less all over the world4 ,no4 #a shows a case which1 though at first sight an aggravated one of a rocky substratum1 is in reality that of some of the best fruit lands in the ,state4 ,the limited surface-soil is very rich1 and is directly derived 7as a 8sedentary0 soil7 from the underlying bedrock slate4 ,but this it will be noted stands on edge1 and the roots of trees and vines wedge their way along the cleavage planes of the slate to considerable depth1 deriving from them both nourishment and moisture4 ,under similar conditions the ,california laurel1 usually found on the banks of streams1 grows on the summits of rocky ridges in the ,coast ,ranges4 ,the case of ,no4 #b is quite otherwise4 ,here the shale lies horizontally1 and though much softer than the slate of the first column1 obstinately resists the penetration of roots2 so that the land1 though fairly provided with plant-food1 is almost wholly useless for cultivation4 ,it is naturally covered with low1 stunted shrubs or chaparral2 only here and there1 where a cleft has been caused by earthquakes or subsidence1 a large pine tree indicates that nourishment and moisture exists within the refractory clay stratum1 and suggests blasting as a means of rendering the land fit for trees at least4 ,illustration3 ,,faulty ,,lands4 ,,california ,,fig4 #ce4--;,faulty ,lands1 ,california4 ,no4 #c is a case similar to that of ,no4 #b1 only there is here a dense unstratified mass of red clay1 of good native fertility4 ,it is here that the expedient of blasting the tree holes with dynamite was first successfully employed1 in central ,california4 ,for lack of this1 extensive tracts of similar land in southern ,california1 planted to orchards1 have completely failed of useful results after three years of culture4 ,no4 #d shows a typical case of calcareous hardpan obstructing the penetration of roots1 even though usually interrupted at intervals1 because of the formation occurring mostly in swales1 along which the sheets lie more or less continuously4 ,here also1 blasting will generally permit the successful growth of trees and vines1 whose roots frequently will1 in time1 wholly disintegrate the hardpan and thus render the land fit for field cultures4 ,the depth at which such hardpan is formed usually depends upon the depth to which the annual rainfall penetrates4 7,see below1 page #ahc74 ,nos4 #d1 #e1 and #f all illustrate cases of intrinsically fertile1 very deep soils1 shallowed by obstructions which in the case of ,no4 #d are hardpan sheets1 while in ,no4 #e the intervention of bottom water limits root penetration1 hence restricts the use of the land to relatively shallow-rooted crops1 and the use of only a few feet of the profusely fertile soil4 ,such is the case where bottom water has been allowed to rise too high1 through the use of leaky irrigation ditches4 ,no4 #f illustrates a case not uncommon in sedimentary lands1 where bottom water is quite within reach of most plants1 but is prevented from being utilized by the intervention of layers of coarse sand or gravel1 through which the water will not rise2 and the roots1 while they would be able to penetrate1 are not near enough to feel the presence of water underneath and therefore spread on the surface of the gravel1 suffering from drought within easy reach of abundance of water4 ,the 8going-back0 of large portions of orange orchards in the ,san ,bernardino ,valley of ,california has been thus brought about2 and unfortunately this state of things is almost beyond the possibility of remedy4 ,illustration3 ,,fig4 #cf4--;,almond ,tree on ,hardpan4 ,paso ,robles ,substation1 ,cal4 ,injury from ,impervious ,substrata4--,the injurious effects of a difficultly penetrable subsoil have already been discussed and are self-evident4 ,when the substratum is a dense clay1 the rise of moisture from below being very slow1 it can easily happen that the roots cannot penetrate deep enough in time for the coming of the dry season1 and that thus the crop will suffer4 ,the case will be still worse when hardpan cemented by lime or silex limits root-penetration1 as well as proper drainage4 ,in such cases the culture of field crops often becomes impracticable1 even with irrigation1 as its frequent repetition1 besides being costly1 can rarely be commanded4 ,in the case of trees1 the limitation of root-penetration results in the spreading-out of the roots on the surface of the impenetrable layer2 as shown in figure #cf1 which exhibits a root-development that would be quite normal in the regions of summer rains1 but is wholly abnormal in the arid region1 and results in the unprofitableness or death of the trees4 ,it has often been attempted in such cases to plant trees in large holes dug deep into the subsoil and refilled with surface earth and manure4 ,all such attempts result in failure1 if only because the excavation inevitably fills with water1 which will soak away but very slowly into the dense substrata1 and will thus injure or drown out the roots4 ,besides1 the latter will remain bunched in the loose earth1 and will thus be unable to draw either moisture or nourishment from the surrounding land4 ,it is absolutely necessary to remedy this by loosening the substrata1 if success is to be attained4 ,shattering of ,dense ,substrata by ,dynamite4--,the permanent loosening of dense substrata is best accomplished by moderate charges 7 to pounds7 of 8,no4 #b0 dynamite at a sufficient depth 7#c to #e feet74 ,the shattering effect of the explosive will be sensible to the depth of eight feet or more1 and will fissure the clay or hardpan to a corresponding extent sidewise4 ,if properly proportioned the charge will hardly disturb the surface2 but if this be desired1 from #a to #b pounds of black powder placed above the dynamite will throw out sufficient earth to plant the tree without farther digging4 ,where labor is high-priced this proves the cheapest as well as the best way to prepare such ground for tree planting2 and it has often been found that in the course of time1 the loosening begun by the powder has extended through the mass of the land so as to permit the roots to utilize it fully1 and even to permit1 in after years1 of the planting of field crops where formerly they would not succeed4 ,leachy ,substrata4--,while we may thus overcome the disadvantages of a dense subsoil or hardpan1 there is another difficulty not uncommonly met with in alluvial lands1 which cannot be so readily remedied4 ,it is the occurrence1 at from two to six feet depth1 of coarse sand or gravel1 through which capillary moisture will not ascend1 but through which irrigation water will waste rapidly1 leaving the overlying soil dry4 ,then unless very frequent irrigation can be given1 the crop will suffer from drought1 unless indeed the gravel itself is filled with bottom water upon which the root-ends can draw4 ,this case is a common one in the larger valleys of the arid region1 and in time of unusual drought the sloughs originally existing1 but since filled up1 will be clearly outlined by the dying crops1 while outside of the old channels there may be no suffering4 8,going-back0 of ,orchards4 ,on such land as this1 and on such as has a shallow soil underlaid by an impervious subsoil1 trees will often grow finely for three to five years2 then suddenly languish1 or turn yellow and die1 as the demand of their larger growth exceeds what moisture or plant-food the shallow soil and subsoil can supply4 ,enormous losses have arisen from this cause in many portions of the arid region1 but more especially in ,california1 owing to the implicit confidence reposed even by old settlers1 and still more by newcomers1 in the excellence of the lands1 as illustrated by farms perhaps a short distance away1 but differently situated with respect to the country drainage and the geological formations4 ,all such disappointments could have been avoided by an intelligent observation of the substrata1 either by probing or digging4 ,important as is such preliminary examination in the region of summer rains1 it is a vitally needful precaution in the arid region1 where the margin between adequate and inadequate depth of soil and moisture-supply is much smaller4 ,when farmers note such distress in the orchard1 the first idea usually is that fertilization is needed4 ,this in the almost universally very rich lands of the arid region is rarely the case until after many years of exhaustive cultivation1 and is scarcely ever of more than passing benefit in such cases4 ,the first suggestion should always be an examination of the substrata1 and especially of the deeper roots2 in the diseased or thirsty condition of which the cause of the 8die-back0 or yellowing will commonly be found4 ,of course no amount of fertilization can permanently remedy such a state of things1 arising from impervious substrata1 coarse gravel1 or shallow bottom water4 ,hardpan4--,by 8hardpan0 is understood a dense and more or less hardened layer in the subsoil1 which obstructs the penetration of both roots and water1 thus materially limiting the range of the former both for plant-food and moisture1 and giving rise to the disadvantages following such limitation1 as described in the case of dense subsoils4 ,the hardpans proper differ from the latter1 however1 in being usually of limited thickness only2 the direct consequence of their mode of formation1 which is not direct deposition by water or other agencies1 but the infiltration of cementing solutions into a pre-existing material originally quite similar to that of the surface soil4 ,such solutions usually come from above1 more rarely from below1 and are of very various composition4 ,the solutions of lime carbonate in carbonated water have already been referred to in this connection2 as has also the fact that corresponding solutions of silica1 associated more or less with other products of rock decomposition 7see chapters #b and #d7 are constantly circulating in soils4 ,the surface soil being the portion where rock-weathering and other soil-forming processes are most active1 these solutions are chiefly formed there2 and according as their descent into the substrata is unchecked1 or is liable to be arrested at some particular level1 whether by pre-existing close-grained layers or by the cessation of rains1 the subsequent penetration of air1 and evaporation of the water alone by shallow-rooted plants1 may cause the accumulation of the dissolved matter at a certain level1 year after year4 ,finally there is formed a subsoil-mass more or less firmly cemented by the dissolved matters1 sometimes to the extent of stony hardness 7lime carbonate in the arid regions1 kankar of ,india71 more usually soft enough to be penetrated by the pick or grubbing hoe1 and sometimes by the stronger roots of certain plants2 but resisting both the penetration and the assimilation of plant food by the more delicate feeding roots4 ,nature of the ,cements4--,the nature of the cements that serve to consolidate the hardpan mass is substantially the same as those already mentioned in the discussion of sandstones 7chapt4 #d1 p4 #ee72 with the addition of those formed1 usually in connection with siliceous solutions1 by the acids of the humus group4 ,the latter class of hardpans is especially conspicuous in the case of swampy ground and damp forests1 where 8moorbedpan0 and reddish 8ortstein0 7the latter particularly developed in the forests of northern ,europe1 where it has been studied in detail by ,mller and ,tuxen#fe1 are characteristic47 ,the latter gives for a characteristic sample of the reddish hardpan underlying a beech forest in ,denmark a content of from #b4bj to #d4dj of ulmic compounds1 and shows that the color is due to these and not1 as had been supposed1 to ferric oxid1 which is present only in minute quantities4 #fe ,see 8,studien ber die natrlichen ,humusformen10 by ,dr4 ,p4 ,e4 ,mller4 ,bog ore1 ,moorbedpan1 ,ortstein4--,it is otherwise with moorbedpan1 which often consists of a mass of bog iron ore permeated more or less with humous substances1 which impart to it the dark brown tint so often seen also in the 8black gravel0 spots of badly-drained land4 ,on the whole1 however1 ferric cements are much less frequently found in hardpans than in sandstones formed above ground4 ,clay substance washed from the surface into the subsoil by rains 7chapter #aj1 p4 #afa7 always helps materially to render the hardpan impervious when afterwards cemented1 a much smaller proportion of the cementing material sufficing in that case to form a solid layer4 ,in such cases however the cement is rarely of a calcareous nature1 since lime prevents the diffusion and washing-down of the clay4 ,it is mostly siliceous or zeolitic2 if the former1 acid will have little or no effect upon the solidity of the hardpan2 while if zeolitic1 acid will pretty promptly disintegrate it4 ,the presence of humus acids in the cements1 if not apparent to the eye1 is readily demonstrated by immersing the hardpan fragment in ammonia water or a weak solution of caustic soda2 when if humus acids are the main cementing substance the fragment will fall to crumbs1 or be softened to an extent corresponding to the amount of the humus present4 ,calcareous hardpan is1 of course1 readily recognized by its quick disintegration by dilute acid1 with evolution of carbonic gas4 ,in 8alkali0 soils containing sodic carbonate 78black alkali07 there is commonly found at the depth of two or three feet an exceedingly refractory hardpan resulting from the accumulation of puddled clay 7see above chapt4 #d1 p4 #fb7 in the subsoil1 or sometimes even on the surface of depressed spots4 ,this hardpan1 easily destroyed by the use of gypsum and water1 is described more in detail in chapter #bb1 on alkali soils2 it blues red litmus paper instantly4 ,the ,causes of ,hardpan4--,the recognition of the cause of hardpan is of considerable importance to the farmer1 because of the influence of the nature of the cement and the causes of its formation upon the possibility and methods of its destruction1 for the improvement of the land4 ,it may be said in general that inasmuch as the cause of the formation of hardpan is a stoppage of the water in its downward penetration1 the re-establishment of that penetration will tend to prevent additional induration2 moreover1 experience proves that whenever this is accomplished even locally1 as around a fruit tree in an orchard1 the hardpan gradually softens and disappears before the frequent changes in moisture-conditions and the attack of roots4 ,the use of dynamite for this purpose in ,california has already been referred to2 it seems to be the only resort when the hardpan lies at a considerable depth4 ,when it is within reach of the plow1 it may be turned up on the surface by the aid of a subsoiler and will then gradually disintegrate under the influence of air1 rain and sun4 ,but when the hardpan is of the nature of moorbedpan1 containing much humic acid and perhaps underlaid by bog iron ore1 the use of lime on the land is indicated1 and will in the course of time destroy the hardpan layer4 ,this is the more desirable as in such cases the surface soil is usually completely leached of its lime content1 and is consequently extremely unthrifty4 ,woodlands of northern countries bearing beech and oak are especially apt to be benefited by the action of lime on the 8raw10 acid humous soil and underlying hardpan1 which is commonly underlaid by a leaden-blue sandy subsoil 78,bleisand0 of the ,germans1 8,podzol0 of the ,russians7 colored brown by earth humates and mostly too moist in its natural condition to permit of adequate aeration4 ,these soils are usually of but moderate fertility1 and are best suited to forest growth unless somewhat expensive methods of improvement can be put into practice4 8,plowsole40--,an artificial hardpan is very commonly formed under the practice of plowing to the same depth for many consecutive years4 ,the consolidated layer thus created by the action of the plow 7hence known as plowsole7 acts precisely like a natural hardpan1 and is sometimes the cause of the formation of a cemented subsoil crust simulating the natural product4 ,this is most apt to occur in clayey lands1 and greatly increases the difficulty of working them1 while detracting materially from the higher productiveness commonly attributed to them as compared with sandy lands4 ,of course it is perfectly easy to prevent this trouble by plowing to different depths in consecutive years1 and running a subsoil plow from time to time4 ,in this case1 also1 lime will generally be very useful and be found to aid materially in the disintegration of the 8plowsole40 ,it is hardly necessary to insist farther upon the need of the examination of land to be occupied1 for the existence of hardpan or other faulty subsoil1 which may totally defeat for the time being the farmer's efforts1 or make him lose his investment in plantations after a few years4 ,probing by means of the steel rod described above 7p4 #agg7 or boring with a post-hole auger2 or finally1 if necessary1 digging a pit to the proper depth 7from four to six feet in the arid region71 should precede every purchase of new or unexplored agricultural land4 ,marly ,substrata4--,among the causes of failure occasionally found in the case of the 8going-back0 of orchards1 is the occurrence of strongly calcareous or marly substrata1 at depths which in the humid region would not be reached by the roots1 but in the course of a few years are inevitably penetrated by the roots of trees in the arid region4 ,then there appears a stunting of the growth1 and sometimes a yellowing of leaves1 or chlorosis1 due to the influence of excessive calcareousness at the depth of four or five feet4 ,for this of course there is no remedy except the planting of crops which1 like the mulberry1 ,texas grapes1 ,chickasaw plum and others1 are at home on such lands2 which in the ,eastern states are naturally occupied by the crab apple1 honey locust and wild plums4 ,,chapter ,,xi4 ,,the ,,water ,,of ,,soils4 ,,hygroscopic ,,and ,,capillary ,,moisture4 ,when it is remembered that from #fe to over #ij of the fresh substance of plants consists of water1 the importance of an adequate and regular supply of the same to growing plants is readily understood4 ,but it seems desirable1 before discussing the relations of water to the soil and to plant life1 to consider first the physical peculiarities which distinguish it from nearly all other substances known4 ,that it is colorless1 tasteless1 inodorous1 and also chemically neutral1 alone constitutes a group of properties scarcely found in any other fluid4 ,but its special adaptation to its functions in relation to vegetable and animal life are much more fundamental1 as is shown in the table of its physical constants as compared with other well-known substances1 given below4 ,,physical ,,factors ,,of ,,water ,,compared ,,with ,,other ,,substances 7,,per ,,unit ,,weight74 ,capillary ascent in glass tubes ,specific ,heats4 of one mm4 diameter4 ,water #ad mm4 ,water #a4jjj ,alcohol #f mm4 ,ice 4#ejb ,olive oil #a mm4 ,steam 4#dge ,clay1 ,glass 4#ahj-4bjj ,charcoal 4#bda ,,heat ,,relations4 ,wood 4#jcb ,density4 ,gold1 ,lead 4#jcb-4jca ,zinc 4#jif ,water at #j ,c4 7freezing ,steel 4#aai pt47 4#iiihh ,water at #d 7,maximum ,heat of fusion4 density7 #a4jjjjj ,water 7,ice7 #hj ,cal4 ,water at #ae ,c4 7ordinary ,metals #e-bh 8 temperature7 4#iij ,salts1 7incl4 silicates7 #dj-fc 8 ,ice at #j 7freezing pt47 4#ibhjj ---------------------------------------- --------------------------- ,heat of ,evaporation4 ,water at #bj;,c4 #fac ,cal4 8 8 #ajj;,c4 #fcg 8 ,alcohol #bji 8 ,spirits of ,turpentine #fg 8 ----------------------------------- ,summarizing the meaning of the data given in the above table with respect to organic life1 we see1 first1 that water rises higher both in the soil and in the tissues of the plant than any other liquid4 ,second1 that as its density decreases in cooling after a certain point is reached1 it freezes at the surface instead of at the bottom1 as other liquids do2 and as solid water 7ice7 is lighter than fluid water1 ice stays at the surface and is readily melted when spring comes4 ,third1 since its temperature changes more slowly than that of any other liquid1 it serves to prevent injuriously rapid changes of temperature in plants and animals as well as in soils4 ,its high 8heat of fusion0 also serves to prevent quick freezing of plant and animal tissues1 so that the brief prevalence of a low temperature may be more readily borne4 ,finally1 the large amount of heat absorbed in evaporation of water serves to keep both plants and animals cool under excessive external temperatures which would otherwise quickly destroy life4 ,capillarity or ,surface ,tension4--,in this table it will be noted1 first1 that water rises higher in fine 78capillary07 or hair tubes than the other fluids mentioned1 which fairly represent all others4 ,no other fluid approaches water in the height to which it will rise#ff in either soils or plant tissues4 ,were its capillary factor no higher than1 e4 g41 that of oil or alcohol1 trees could not grow as tall as we find them1 and the water supply from the substrata1 and all the movements of water in the soil1 and hence plant growth1 would be similarly retarded4 ,it is easy to verify these differences by immersing a cylinder of clay soil 7or a cotton wick7 in water on the one hand1 and in oil or alcohol on the other4 ,notwithstanding the greater fluidity of alcohol as compared with water1 the latter will be found to fill the porous mass much more quickly4 #ff ,excepting only the water-solutions of certain salts1 among which common salt1 kainit and nitrate of soda are of agricultural interest4 ,common salt may increase the capillary rise to the extent of more than five per cent4 ,the smaller the diameter of the tube1 the higher will the water rise in it1 and the greater will be the curvature of its upper surface1 to which the rise is sensibly proportional4 ,but in the case of liquids which do not 8wet0 the walls of the tube 7as in that of mercury and glass71 the curve 7meniscus7 is convex1 instead of concave1 and the liquid is depressed instead of rising4 ,it is in its relations to heat1 however1 that water is specially distinguished from other substances2 and these differences are most vital not only to living organisms1 but to the entire economy of ,nature4 ,density4--,as regards the density or specific gravity of water 7which is by common consent assumed as the unit of comparison71 it will be seen from the 8,density0 table that whereas all other bodies contract and become more dense as they grow colder1 water has its point of 7fluid7 8maximum density0 at #d;,c4 7#di4b ,fahr471 and expands as it grows colder1 until at #j;,c4 7#cb ,fahr47 it solidifies into ice4 ,in so doing it departs still farther from the rule obtaining with all other bodies 7excepting certain mixtures1 such as type metal7 and again expands so as to decrease the density from 4#iiihh to 4#ibhjj2 thus causing ice to float on water at the freezing point4 ,hence water1 unlike all other fluids1 solidifies first on the surface2 and but for this1 the thawing of the winter's ice1 which would be formed at the bottom of rivers and lakes1 would be deferred until late in summer4 ,the expansion of water in freezing is forcibly illustrated in the bursting of water pipes and pitchers in winter2 in the soil1 the ice forming in the interstices serves to loosen the compacted land and give it better tilth for the ensuing season4 ,specific ,heat4--,considering next1 the column showing the 8specific heat0 of water as compared with other substances1 we see that it exceeds all other known bodies in the amount of heat required to change its temperature2 hence again1 its heat capacity is taken as the unit to which all others are compared4 ,the figures given in the table show that even ice and steam require for equal weights only about half as much heat 7or burning of fuel7 to change their temperature 7e4 g41 #a degree7 as would liquid water4 ,but earthy matters1 such as clay or soil and glass1 require only one-fifth as much heat for a similar change2 charcoal only about one-fourth as much4 ,but vegetable matter as represented by wood on the one hand1 and gold and lead on the other1 require only about one-thirtieth as much heat as an equal weight of water2 zinc about one-tenth as much1 steel somewhat more4 ,it is thus plain that masses of water act powerfully1 more than any other substance1 as moderators of changes of temperature by their mere presence4 ,the body of an animal or plant is protected against violent changes by the presence of from #fj to #ij of liquid water1 the temperature of which can only be raised or lowered slowly2 and the presence of the sea tempers the climates of coasts and islands as compared with the heat or cold occurring in the interior of the continents4 ,ice4--,again1 it is shown in the table that the heat required to melt ice is greater than in the case of any other substance1 especially the metals2 which when once heated to the fusing point1 require only a very little more heat to become liquid4 ,the fusion of salts 7including silicate rocks7 requires more heat than does that of the pure metals4 ,vaporization4--,in the amount of heat required for its vaporization water is also especially pre-eminent1 and potent in its influence upon organic life4 ,the table shows that the evaporation of water requires six hundred heat units#fg as compared with alcohol1 requiring only two hundred2 while spirits of turpentine1 the representative of a large proportion of vegetable fluids1 needs but sixty-seven4 #fg ,a heat unit1 or 8calorie10 is the amount of heat required to raise the temperature of a unit-weight 7pound1 kilogram1 or gram7 of water one thermometric degree4 ,according to the unit-weight and thermometric scale used1 the figures will vary1 but in this text the basis is understood to be kilograms and the centigrade scale4 ,the practical result is that evaporation of water from the surface of animals and the leaves of plants1 is exceedingly effective in preventing excessive rise of temperature1 the heat of the sun and air being spent in evaporating the perspiration of animals and plants before an injurious rise of temperature1 such as would cause sunstroke in animals1 and wilting or withering in plants1 can occur4 ,but since evaporation is most rapid in dry air1 it follows that the cooling effect will be the greater in the arid regions than in the humid4 ,in the latter1 therefore1 sunstroke is much more frequent than in the fervid regions of the arid west1 even though the temperature in the latter may be higher by twenty or twenty-five degrees ,fahrenheit4 ,white men who would soon succumb if they attempted to work in the sun in ,mississippi or ,louisiana when the thermometer stands at #ie;,f4 will experience no inconvenience under the same conditions in the dry atmosphere of the ,great ,valley of ,california4 ,solvent ,power4--,to the exceptional properties of water discussed above1 should be added another hardly less important one1 viz41 that of being an almost universal solvent especially of mineral matters1 including even those which1 like quartz1 appear to be most insoluble and refractory 7see chapt4 #c74 ,the water of the soil is thus enabled to convey to the roots of plants1 in solution1 all kinds of plant food contained in the soil4 ,it should be noted that distilled 7hence also rain-7 water is a more powerful solvent1 e4 g41 of glass1 than ordinary waters containing mineral matter1 and even free acids4 ,practically1 plants take up all their water supply from the soil in the liquid form2 and hence the soil-conditions with respect to this supply are of the most vital importance to plant growth4 ,the most abundant supply of mineral plant food may be wholly useless1 unless the physical conditions of adequate soil-moisture1 access of air1 and warmth1 are fulfilled at the same time4 ,on the other hand1 comparatively few plants are adapted to healthy growth in soils saturated with water1 or in water itself2 and but few among these are of special interest from the agricultural standpoint4 ,water-requirements of ,growing ,plants4--,the amount of water contained in any plant at one time1 however large1 is but a small proportion of what is necessary to carry it through its full development4 ,when we measure the amount of water actually evaporated through the plant in the course of its normal growth1 we find it to be several hundred times the quantity of dry vegetable substance produced2 varying according to the extent and structure of the leaf-surface1 the number and size of the breathing pores 7stomata7 of the leaves1 and the climatic conditions 7including specially the duration of active vegetation1 and temperature during the same71 from #bbe to as much as #iab times the weight of the mature1 dry plant4 ,the following are extreme figures for water consumption of different plants as reported by different observers1 viz41 ,lawes and ,gilbert in ,england1 ,hellriegel in northern ,germany1 ,wollny in ,southern ,germany 7,munich71 and ,king in ,wisconsin3 ,wheat1 #bbe to #cei2 barley1 #bfb to #ggd2 oats1 #djb to #ffe2 red clover1 #bdi to #dec2 peas1 #bce to #ddg2 mustard and rape1 #hde to #iab respectively2 the latter figure being the maximum thus far reported4 ,the highest figures given are throughout very nearly those of ,wollny1 working in the very rainy climate of ,munich4 ,evaporation from ,plants in ,different ,climates4--,it might be expected that in countries where the air is usually moist1 the evaporation will1 other things being equal1 be less than where it is commonly far below the point of saturation4 ,but the 8guardian cells0 7stomata7 of the leaf pores possess the power of regulating1 to a certain extent1 the evaporation from the leaf-surface in accordance with temporarily prevailing conditions1 so as to allow free evaporation in moist air1 but to prevent the wilting and drying-up of the leaf in hot and dry air1 save in extreme cases4 ,moreover1 plants adapted to arid conditions are usually provided with additional safeguards in the form of thick1 non-conducting layers of surface cells1 or long channels connecting the interior tissue with the breathing-pores on the surface4 ,often hairy1 scaly or viscous coverings serve the same end4 ,on the other hand1 when the air is very moist1 so as to check evaporation1 water is sometimes found secreted in minute droplets around the breathing-pores of the leaves1 since its ascent is a necessary condition of nutrition and development4 ,relation between ,evaporation and ,plant-growth4--,there is not in all cases any direct relation between the amount of evaporation and plant growth2 but experience1 as well as numerous rigorous experiments have shown that under ordinary conditions of culture1 and within limits varying for different soils and crops1 production is almost directly proportional to the water supply during the period of active vegetation4 ,on the basis of ,hellriegel's results1 showing that wheat uses 7in ,germany7 about #dce tons1 or nearly four acre-inches of water in the production of one ton of dry matter1 and assuming the ratio of grain to straw to be #a3a4e1 ,king calculates the following table of probable production under different moisture conditions 7,physics of ,agriculture1 page #adj73 ,,yield ,,per ,,acre4 ,number of ,weight of ,weight of ,total ,water used4 ,bushels4 ,grain4 ,straw4 ,weight4 ,acre-inches4 ,tons4 ,tons4 ,tons4 ---------------------------------------- ------------- #ae 4#de 4#fge #a4abe #d4dih #bj 4#fj 4#ij #a4ejj #e4iih #be 4#ge #a4abe #a4hge #g4dig #cj 4#ij #a4cej #b4bej #h4iig #ce #a4je #a4ege #b4fbe #aj4die #dj #a4bj #a4hjj #c4jjj #ab4jjj ---------------------------------------- ------------- ,s4 ,fortier has made several series of tests to determine the actual yield of grain crops under field conditions when supplied with different amounts of water4 ,two of these were made at the ,montana experiment station in #aijb and #aijc1 7see reports of these years71 in large tanks placed in a field1 level with the ground4 ,the results of the last year's experiments are shown graphically in the figure below1 from which it will be seen that the yield increased quite regularly with the amount of water supplied1 up to the depth of #cf inches of water4 ,illustration3 ,,fig4 #cg4--;,experiments on ,cereal production with various amounts of water 7,fortier1 ,report ,mont4 ,expt4 ,sta41 #aijc74 ,it should be noted that in this case 7and as usual7 not only the quantity but the quality of the grain was greatly improved as the water-supply increased1 it becoming larger and more uniform in size4 ,of similar experiments made in the ,san ,joaquin ,valley1 ,california1 in #aijd1 ,fortier says3#fh 8,in experimenting with barley last winter the natural rainfall1 which amounted to #d inches during the period of growth1 produced at the rate of nine bushels per acre1 while the application of sixteen inches of water increased the yield to twenty-two bushels per acre4 ,in the same case2 of wheat1 the rainfall1 alone1 produced straw1 but no grain2 four inches of additional irrigation water produced a yield at the rate of ten bushels1 and sixteen inches of water increased the yield to thirty-eight bushels per acre40 #fh 8,water and ,forest10 ,january1 #aije4 8,the ,use of ,water10 by ,s4 ,fortier4 ,it is thus obvious that1 other things being equal and with conditions sufficiently favorable for the growth of crops1 the rule as formulated above is verified in practice4 ,whitney 7,bulletin #bb1 ,bureau of ,soils1 ,u4,s4 ,dept4 ,agr471 has carried this rule so far as to claim that in all soils1 the moisture supply is the only important factor1 and that so long as this is provided for1 soil fertility continues indefinitely without replacement of ingredients withdrawn4 ,the latter conclusion is so thoroughly disproved by experience as well as experiment that it hardly requires discussion here4 ,whether plants1 especially cultivated ones1 are capable of adapting themselves to arid conditions so as to be capable of producing satisfactory crops with less water than is actually consumed in the humid region1 has not been directly determined4 ,such is1 however1 the impression produced by farming experience2 and the fact that among the common weeds of arid ,california are mustard and rape1 cited by ,wollny#fi as requiring over three times as much water as does maize for the production of one part of dry matter1 lends color to the supposition that in some manner these1 and probably other plants1 use more water in humid than in dry climates 7see this chapt4 p4 #bab74 #fi ,see ,wollny's experiments1 ,forsch4 ,agr4 ,phys4 ,vol4 #bj1 p4 #eh4 ,it is therefore impossible to assign a definite figure for the amount of water required by vegetation at large2 and even for one and the same plant1 only approximations conditioned upon climatic factors can be given4 ,we can in many cases1 however1 assign for one plant1 or for certain groups of plants1 the amounts of water producing the best results 78optimum07 and the least amount 78minimum07 compatible with a paying crop1 that must be furnished during the growing season1 to produce certain results4 ,for when instead of fruiting1 it is desired that the crop should produce the largest possible amount of vegetable substance1 as in the case of forage crops1 a larger amount of water will usually be serviceable4 ,different conditions of ,soil-,water4--,water may be contained in the soil in three different conditions1 viz43 #a4 ,from absorption of water vapor2 ,hygroscopic water4 #b4 ,liquid water held suspended between the soil particles so as to exert no hydrostatic pressure2 capillary water1 or water of imbibition4 #c4 ,liquid water seeking its level2 bottom1 ground or hydrostatic water4 ,,hygroscopic ,,water4 ,soils artificially dried so as to deprive them of all their moisture1 when exposed to moist air absorb water vapor with great energy at first2 both the rapidity of absorption and the amounts absorbed1 when full time is given1 varying greatly with their nature4 ,sandy soils1 broadly speaking1 absorb the smallest amounts2 while clayey soils1 and those containing much humus1 or finely divided ferric hydrate1 take up the largest proportion4 ,the figure expressing the amount of aqueous vapor absorbed at the standard temperature of #ae ,cent41 is called the coefficient of moisture absorption4 ,for one and the same substance1 this coefficient rises as the grain becomes finer1 the surface being correspondingly increased 7see chapt4 #f74 ,the table below indicates the effect of the three substances mentioned in increasing moisture absorption as compared with a very sandy soil from the pine woods of ,mississippi1 and a gray silt or 8dust0 soil from ,washington1 very fine-grained but poor both in humus and ferric hydrate4 7,for details of the physical composition of the ,mississippi soils see table in chapt4 #f1 p4 #ic74 ,a highly ferruginous soil from ,oahu shows plainly the effect of that substance4 ,,table ,,showing ,,influence ,,of ,,silt1 ,,sand1 ,,clay1 ,,ferric ,,hydrate1 ,,and ,,humus ,,on ,,moisture ,,absorption4 #bdh #gi #bch #bcj ,miss4 ,wash'n,miss4 ,miss4 ,pine ,dust ,white,flatwoods ,hills ,soil4,pipe ,clay ,sandy ,clay4 ,soil4 ,loam4 ---------------------------------------- ------------------ ,hygr4 ,moisture #b4dh #d4ib #i4ji #i4cc ,clay #b4id #a4bggd4fe #be4dh ,ferric ,hydrate #a4fd 4#ae ,humus 4#ee 4#dd #j4jj 4#ej ,finest ,silts 74#ja-4jbej mm47 #fj4aj #de4jdbc4ae #fh4fj ,sands1 f4 and c4 74#jbej-4ej mm47 #ca4bj #db4dj 4#bj #d4gj ---------------------------------------- ------------------ #bdf #bbj #bae ,misc4 ,oahu ,miss4,miss4 ,ferruginous,ferruginous,marsh,marsh ,clay ,laterite4 ,muck4,soil4 ,soil4 ---------------------------------------- ------------------------ ,hygr4 ,moisture #ah4fj #ai4ff #ba4jjae4dj ,clay #bh4ae 8 ,tr4 ,tr4 ,ferric ,hydrate #ab4aj #da4jj ,humus little #c4cc #ff4ajai4hc ,finest ,silts 74#ja-4jbej mm47 #dj4cc #de4ff #cc4id #h4gj ,sands1 f4 and c4 74#jbej-4ej mm47 #ae4fa #gj4ah ---------------------------------------- ------------------------ ,it will be noted that the greater fineness of grain in the ,washington dust soil induces a higher absorption of moisture than occurs in the sandy soil from ,mississippi1 although the latter contains more clay4 ,comparison of the figure for the ,mississippi pipe-clay and clay soil with the ferruginous soils1 from the same state and from ,oahu1 indicate plainly the influence of the ferric hydrate in increasing absorption2 although in the latter case the clay determination was not made1 because of the excess of ferric hydrate4 ,the influence of humus is plainly shown in the case of the marsh muck and soil1 neither of which contain any appreciable amount of either clay1 or ferric hydrate in the finely diffused condition4 ,the relatively slight difference in the absorptions of muck and soil is due to the only partial humification of the organic matter in the former1 while in the soil the humification is sensibly complete1 and the sand forming the body of the material serves to render it more loose4 ,these data1 referring to natural materials1 while not as complete as could be desired1 are sufficient to prove the facts1 and seem preferable to any artificially devised imitation of their kind4 ,influence of ,temperature1 and ,degree of ,air-,saturation4--,the amount of moisture absorbed varies materially both with the temperature1 and with the degree of saturation of the air to which the soil is exposed4 ,schbler1 ,knop and other earlier observers1 operating with earth exposed to air only partly saturated1 and with soil layers of considerable thickness 7in watch glasses71 found that the absorption decreased as the temperature increased1 according to a law formulated by ,knop4 ,the writer found that under the conditions established in the experiments of ,knop and others1 the air was not nearly saturated1#gj so that these determinations are marred by ineliminable faults1 the more as the soils used are only designated in general terms1 as 8garden soil10 8loam10 8peaty land10 etc41 without any definite indication of their actual physical or chemical constitution4 ,the writer therefore undertook to correlate these coefficients1 determined with respect to completely saturated air1 with the physical composition of certain soils1 as determined by means of the methods heretofore described4 #gj ,it should be understood that it is by no means easy to insure full saturation in any considerable volume of air4 ,it has generally been considered sufficient to cover with water the bottom of the space in which absorption was to occur4 ,the writer found that in order to insure uniform results1 it was necessary to cover the entire inner surface of the vessel with wet blotting paper1 and even then to exclude carefully all circulation of air by padding the joints with such paper4 ,when only the bottom of the box was covered1 samples placed at different levels above the water surface gave discordant results4 ,it was also observed that whenever the thickness of the soil layer exceeded about one millimeter1 a long time was required for full saturation2 during which inevitable changes of temperature would bring about a deposition of dew on the soil1 greatly exaggerating the absorptive coefficient4 ,in the chamber used at the ,california station for soil saturation1 dimensions #ab #ah #ai inches high1 the same soil was exposed on a shelf close to the surface of the water1 another midway up1 a third near the lower surface of the cover2 liquid water being in the bottom of the chamber1 and the rest covered with wet blotters4 ,it was found that despite these precautions1 the lowest soil layer absorbed in the same time as much as more than the uppermost one4 ,some of the data so obtained are given in the table of physical soil composition on page #ic1 chapt4 #f4 ,they have since been extensively supplemented by additional determinations1 but without materially changing the coefficients approximately corresponding to the several designations accepted in farm practice4 ,experiments conducted by the writer have conclusively shown that ,knop's law of decrease of absorption with rise of temperature not only is not true for fully saturated air1 but must be reversed2 the fact being that the amount of water absorbed by the soil increases in a fully saturated atmosphere 7i4e41 in presence of excess of water7 as the temperature rises1 at least between #ae and #ce degrees ,cent4 ,thus1 fine sandy soil which at #ae absorbed #b of moisture1 took up #d at #cd2 while loam soil absorbing #g at #ae1 showed nearly #i at #ce2 an increase of #b in each case4 ,but in partially saturated air#ga it was found that1 as stated by ,knop1 the amounts absorbed steadily decrease1 though not according to the law announced by him4 ,taking as a unit the moisture absorbed at #ae1 it was found that in air three-fourths saturated1 of the unit was taken up by the soil2 at half saturation1 nearly the proportional amount2 but at one-fourth saturation the earths absorb materially more than a similar proportion1 being then capable of withdrawing moisture from greatly undersaturated air4 ,since air thus undersaturated occurs not uncommonly in the arid regions of the world1 the fact that the soil cannot be farther dried by such air of the same temperature1 is of some practical significance4 #ga ,the partial saturation to a definite extent was effected by means of solutions of calcium chlorid of different degrees of concentration1 according to the determinations of ,wllner 7,pogg4 ,ann474 ,these solutions were placed in a wide1 flat dish1 over which a layer of soil #a mm4 in thickness was exposed1 all being covered with a bell glass lined inside with the same solution1 so as to insure equal saturation4 ,in view of the highly variable composition of soils and of the doubtless varying hygroscopic properties of their several physical constituents1 it is not to be expected that any one numerical law will hold good exactly for all kinds of lands4 ,mineral powders1 colloidal clay1 ferric hydrate1 aluminic hydrate1 the zeolites1 humus1 and other hydrates known to occur1 doubtless each follow a different law in the absorption of moisture and gases2 so as to modify the hygroscopic properties#gb of the soil in accordance with their relative predominance in each case4 7,see table of absorption of gases1 chapter #ad74 ,utility of ,hygroscopic ,moisture to ,plant-growth4--,the early experimenters considered the hygroscopic moisture of the soil to be of very great importance to the welfare of crops4 ,within the last twenty-five years much doubt has been cast upon this claim1 even to the extent of stating that 8the hygroscopic efficacy of soils must be definitely eliminated from among the useful properties0 7,mayer's ,agriculturchemie1 vol4 #b1 p4 #aca74 ,yet ,mayer himself concedes the cogency of the experiments made by ,sachs1 which proved that dry soil immersed in a 7probably not even fully7 saturated atmosphere is capable of supplying the requirements of normal vegetation2 thus explaining the obvious beneficial effects on vegetation of the summer fogs prevailing in portions of the arid region1 e4 g42 on the coasts of ,california and ,chile4 #gb ,e4 ,a4 ,mitscherlich 7,bodenkunde fr ,land-und ,forstwirthe1 p4 #aef et al47 claims that all determinations of soil hygroscopicity thus far made are grossly incorrect on account of the dew liable to be condensed on the soil layer from fully saturated air1 as the result of slight changes of temperature4 ,he therefore would have all such determination made either in an air-vacuum1 or over a #aj solution of sulfuric acid4 ,such dew-formation1 however1 cannot happen to any appreciable extent under the conditions maintained in the writer's work1 viz1 absorption within a thick-walled 7two-inch7 wooden box of the dimensions given above1 and sunk in the ground in a cellar in which the temperature varies only a few tenths of a degree during #bd hours4 ,the soil layer of one millimeter thickness being put down in the morning1 the #g hour absorption period falls at the time of slightly rising temperature1 as an additional precaution against dew-deposition4 ,mitscherlich fails1 moreover1 to show that this source of error produces any wide or serious discrepancies except under such long absorption periods as he finds it necessary to use because of the great thickness of his soil layers4 ,it is doubtful whether the limits of errors in soil sampling do not greatly exceed any of those involved in the writer's method1 and whether such accuracy as is attempted by ,mitscherlich is of any practical significance4 ,mayer's experiments relied upon to prove the uselessness of hygroscopic moisture to plant growth1 were carried out in flower-pots1 in which it was plainly shown that the plants wilted before even the visible liquid 7capillary7 moisture of the earth was entirely exhausted4 ,but this simply proves that under such artificial conditions1 plants cannot withdraw moisture from the soil rapidly enough for their needs4 ,in nature1 and notably in the arid regions1 the chief supply of water is received through the deep-going main roots1 while the bulk of the active feeding roots of the plant may be surrounded by almost air-dry soil2 under which conditions1 as ,henrici 7,henneberg's ,journ41 #ahfc1 p4 #bhj7 has shown1 slow growth and nutrition occurs even in such plants as the raspberry1 a native of humid climates4 ,but in the arid region this is the normal condition of the native vegetation through most of the rainless summer4 ,that a higher moisture-coefficient does not necessarily imply that a larger amount of moisture can be withdrawn from the soil by the plants1 is undoubtedly true in some1 but not in all cases2 for in soils rich in humus1 the moisture is more freely shared with the roots than in non-humous1 clay lands4 ,the higher moisture-absorption is however of the most unquestionable service in the case of the occurrence of the hot1 dry winds that so frequently threaten the entire crops of some regions4 ,in this case the soil containing the greater amount of moisture requires a much longer time to be dried1 and heated up to the point of injury to the roots1 than in the case of sandy soils of low absorptive power1 whose store is exhausted in a few hours and then permits the surface to be heated up to the scalding point1 searing the stems and root crowns4 ,that such injury occurs much sooner in sandy lands than in well-cultivated clay soils1 is a matter of common note in the arid region4 ,summary4--,the significance of hygroscopic moisture in connection with plant growth may then be thus summarized3 #a4 ,soils of high hygroscopic power can withdraw from moist air enough moisture to be of material help in sustaining the life of vegetation in rainless summers1 or in time of drought4 ,it cannot1 however1 maintain normal growth1 save in the case of some desert plants4 #b4 ,high moisture-absorption prevents the rapid and undue heating of the surface soil to the danger point1 and thus often saves crops that are lost in soils of low hygroscopic power4 ,,capillary ,,water4 ,the liquid water held in the pores of the soil1 in the form of surface films representing the curved surface seen in capillary tubes1 and therefore tending to cause the water to move upwards1 as well as in all other directions1 until uniformity of tension is established1 is of vastly higher importance to plant growth than hygroscopic moisture4 ,it not only serves normally as the vehicle of all plant food absorbed during the growth of the usual crops1 but also1 as a rule1 to sustain the enormous evaporation by which the plant maintains during the heat of the day1 a temperature sufficiently low to permit of the proper operation of the processes of assimilation and building of cell tissue4 ,comparatively few plants have roots adapted to healthy action while submerged in water1 excluding them from free access of the oxygen of the air2 and when such roots are formed by plants not naturally growing in water or swampy ground1 they differ so far from earth-roots in their structure that when transferred to soil they usually die1 normal earth-roots being gradually formed instead4 ,conversely1 there is for all land plants a definite time-limit beyond which their roots cannot live1 or at least remain healthy1 in submersion4 ,thus grain fields will with difficulty recover from a week's total submersion2 while young rice fields will resist considerably longer4 ,when in the resting 7winter7 condition vineyards will bear submergence for thirty-five and even forty days1 deciduous orchards about three weeks2 but when in the growing condition1 injury is suffered much more quickly4 ,it follows that whenever the soil-pores remain completely filled with water for a length of time1 there is danger to the welfare of nearly all plants commonly cultivated in the temperate zones4 ,it is therefore important to know how much water will bring about this undesirable condition in the different kinds of soil4 ,to determine this point we may either employ the determination of pore space by a comparison of the density of the soil constituents 7see chap4 #g1 p4 #ajg7 with the volume weight of the soil2 or we may measure directly the amount of water required to fill the pore-space4 ,for the latter purpose it is only necessary to measure the amount of water 7conveniently flowing from a graduated pipette7 which1 rising slowly from below in a ,u-shaped tube so as to expel all the air before it1 is required to fill a definite weight or volume of the soil entirely full1 so as to rise to its surface4 ,we thus ascertain the amount of empty space existing within the soil1#gc which in the absence of water will ordinarily be filled by air4 #gc ,simple as this operation appears to be1 it is found to be by no means easy to expel with certainty every small air bubble without resorting to means which would destroy the natural condition of the soil2 such as boiling1 or the use of the air-pump4 ,these determinations cannot therefore lay claim to great accuracy4 ,in most cultivated soils1 as already stated1 the air-space constitutes about #be to #ej of their volume2 and this space when filled with water represents what is commonly termed their maximum water capacity or saturation point4 ,it is of interest to know this1 because it has been ascertained from experience that in order that plants may reach their best development1 the capillary water present should not amount to more than #fj1 or less than #dj of its maximum water-holding capacity2 thus leaving about half the pore-space filled with air4 ,this optimum1 however1 varies somewhat for different plants1 some1 like celery1 being more tolerant of excess1 and others being more tolerant of a deficiency of moisture1 as is the e4 g41 egg-plant1 originally a desert growth4 ,capillary ,ascent of ,water in ,soil ,columns4--,when a column of dry soil 7e4 g41 contained in a glass tube closed with muslin at the lower end7 is brought in contact with water1 the latter is soon seen to ascend in the soil1 wetting it and thus changing its color so as to permit of ready observation of its progress4 ,at first the rise is comparatively rapid1 in some cases as much as an inch in one minute2 but it soon slows down and after a time ranging from a few days to many months1 reaches a maximum height beyond which the liquid water will not rise4 ,the ascent is most rapid1 and stops soonest1 in coarse sandy soils2 it rises most slowly1 but in the end considerably higher1 in heavy clay soils4 ,the most rapid continuous rise1 and ultimately the highest1 occurs in salty soils containing but a small proportion of clay4 ,the maximum height of capillary rise thus far observed1 viz4 #aj4ag feet1 was noted in the case of quartz tailings from a stamp mill1 ranging from 4#jje mm4 to 4#jaf mm4 in diameter2 but it took about #ah months' time to reach this maximum4 ,the excessively fine texture of clay opposes great frictional resistance to the movement of the water1 and the same is true of the finest silts1 which1 like clay1 remain almost indefinitely suspended in water4 ,but it must be remembered that while pure grains of silt will in wetting remain unchanged in size1 clay particles1 and the clay incrusting silt grains1 will on wetting swell greatly1 and thus fill up the interstices1 largely closing them up against the passage of water4 ,these facts are exemplified and graphically illustrated below4 ,the soils selected for this illustration1 from ,california localities1 are the following3 ,no4 #bcc4 ,very sandy soil from near ,morano1 ,stanislaus ,county4 ,typical of the noted wheat-growing region of the lower ,san ,joaquin ,valley1 from northern ,merced to ,southern ,san ,joaquin ,counties2 bench or plains lands4 ,first foot4 ,no4 #aaig4 ,sandy alluvial soil from near the confluence of the ,gila and ,colorado rivers1 near ,yuma4 ,very deep1 light and easily cultivated4 ,first foot1 but almost identical to #ae feet4 ,no4 #afh4 ,silty alluvial soil from the old alluvium of the ,santa ,clara ,river1 near ,santa ,paula1 ,ventura ,county4 ,very deep1 very easily tilled2 a typical alluvial loam of the arid region4 ,no4 #afig4 ,black adobe or clay soil1 from the experiment station grounds1 ,berkeley4 ,a heavy clay soil1 originally a swamp deposit1 becoming very tenacious when wet4 ,an excellent wheat soil4 ,the physical analyses of these soils are given below4 ,,physical ,,analyses ,,of ,,typical ,,soils4 ,silt4 ,sand1 ------------------------#b4j to ,clay4 ,fine1 ,coarse1 #fd mm4 4#be to 4#e to #b4 mm4h4 v4 4#e mm4 h4 v4 h4 v4 ---------------------------------------- ------------------------- ,no4 #bcc4 ,morano sandy soil #b4hb #c4jc #c4di #hi4be ,no4 #aaig4 ,gila bottom soil #c4ba #e4ec #ae4db #gb4je ,no4 #aih4 ,ventura silty soil #ae4jb #ae4bd #be4hd #de4da ,no4 #afig4 ,berkeley adobe soil #dd4bg #be4ce #ac4dg #ac4cg ---------------------------------------- ------------------------- ,the most striking feature in this diagram is the very rapid#gd and high ascent in the combination of sediments represented by the ,gila bottom soil4 ,it outstrips at once both the sandy soil from ,stanislaus1 which contains a trifle less of clay1 and the silt soil from ,ventura1 from which at first sight it does not seem to differ widely1 but which contains considerably more clay4 ,it is doubtless the latter which so greatly retards the motion of the water1 as is still farther seen in the case of the clay or adobe soil4 ,it will be noted that on the second and third days1 the ,gila soil had raised the water nearly twice as high as the adobe1 and that it took only #ah hours to raise it nearly the same height as that attained by the ,ventura silt in so many days4 ,but it ceased to rise after the #abeth day1 while the ,ventura soil1 continuing for #aie days1 finally rose #c inches higher4 ,the adobe also continued its rise1 but did not reach the same height as the ,gila soil by nearly two inches4 ,there can be no doubt that the energetic and high rise of the latter proves an important factor in the culture of these lands4 #gd ,the ascent is of course most rapid1 in the large tubes almost instantaneous1 when the capillary space is entirely clear2 but in the complex system of connected air spaces in soils1 the curved paths and the friction obstruct the movement4 ,the coarse sandy soil reached its highest limit1 #af inches1 within six days1 when the silty ,gila soil stood at about double that height4 ,illustration3 ,,fig4 #ch4--;,columns showing heights to which water will rise by capillarity in soils of different physical composition1 and rates of ascent4 ,illustration3 ,,fig4 #ci4--;,capillary ,rise of ,water in ,soil ,sediments of different ,diameters4 ,ascent of ,water in uniform#ge ,sediments4--,loughridge has ascertained the rate of ascent of uniform sediments of different grain-diameters1 with the results shown in the diagram subjoined1 together with the maximum height reached by each4 ,the diagram is very eloquently illustrative of the great differences in the capillary properties of granular sediments of the various grades2 and it would seem that it ought to be possible to deduce from it by a somewhat complex formula the rate and height of ascent of water in any soil of known physical composition4 ,in nature1 however1 the presence of clay and the greater or less degree of flocculation of mixed sediments will always vitiate to a very great extent the results deducible from such calculations2 hence the data conveyed by the observations of ,loughridge must be considered applicable only to granular sediments free from clay and entirely deflocculated4 #ge ,i4 e41 uniform between the narrow limits given4 ,it is curious that in this case the 8clay0 showed a rise markedly below that of the finest granular sediment1 despite the extreme fineness of its particles4 ,this proves plainly that the physical nature of colloid clay is unlike that of the granular sediments2 as has been repeatedly mentioned above4 ,maximum and ,minimum of ,water-holding ,power4--,it is clear that at the base of the columns of soils just considered1 the maximum of water-absorption of which the soil is capable will have been brought about2 while at the top of the same column1 the minimum of possible liquid absorption 7continuous films of water7 will exist4 ,the same minimum moisture-condition will be produced when a limited quantity of water is placed with a large mass of soil2 the moisture will spread to certain limits1 until the surface films of water have all acquired uniform tension2 and will then cease to extend1 except by evaporation and hygroscopic absorption4#gf ,it is clear that the same condition will be brought about in the course of time at the top of a soil column in which water has percolated from above2 and hence the minimum mentioned1 aside from evaporation1 represents approximately the usual condition of the soil near the surface within a variable time after a rain1 or irrigation1 when the descending water column has attained a length corresponding to the height to which the water would have risen from below in a tube arranged as shown on p4 #bje4 ,it is therefore a condition of very frequent occurrence in the arid region4 #gf ,ad4 ,mayer 7,agriculturchemie #b1 p4 #ada7 designates this minimum content of liquid water as the 8absolute0 water capacity of the same2 but it is not obvious wherein this factor is better entitled to this name than would be the maximum 7see ,wollny's ,forsch41 #ahib1 p4 #a474 ,m4 ,whitney 7,rep4 ,proceedings ,ass'n ,agr4 ,coll4 ,exp't ,st'ns1 ,nov4 #aijd7 gives as a new observation the fact that in soils approaching the drought condition water 8does not obey the ordinary physical laws as we recognize them in capillarity40 ,this evidently refers simply to the well-known phenomenon mentioned above4 ,capillary ,water held at ,different ,heights in a ,soil ,column4--,to determine the amounts of water held in the different portions in columns of soils in which water ascends by capillary rise1 the following plan was adopted by the writer in collaboration with ,loughridge 7,rep4 ,calif4 ,sta4 #ahib-d1 p4 #ii74 ,instead of glass tubes the soils to be tested were placed in copper tubes one inch in diameter1 divided into segments six inches long1 and flattened on one side4 ,in the flattened side a slot half an inch wide was left1 and glass plates1 held in position by rubber elastics1 were cemented on the slotted side by means of paraffin1 to prevent a sifting-out of the soil4 ,the short sections can be connected at the ends like joints of stove-pipe1 and the earths can be easily introduced in proper1 even condition4 ,it was thus possible to gain access to any portion of the column at any time1 for the taking of samples4 ,,water ,,contents ,,of ,,soil ,,columns ,,at ,,various ,,heights ,,above ,,water ,,level4 ,no4 #bcc #aaig #afgi ---------------------------------------- -------------------- ,height above ,water,sandy ,soil1,sandy ,alluvium1,adobe1 ,berkeley4 ,level4 ,morano4 ,gila4 ---------------------------------------- -------------------- #dg inches #d4cc #db inches #aj4bf #cf inches #aa4ii #cj inches #ae4bf #bd inches #ba4ci #aj4bfgg #ah inches #bg4fc #bi4dh #ab inches #c4ic #cb4dh #cc4jd #f inches #ad4ae #ce4jd #ch4dg #c inches #ch4di #a inch #bd4cd #cf4fd #dd4da ---------------------------------------- -------------------- #gg ,this figure represents only a temporary condition2 the full height of #df inches was not reached until the #aieth day4 ,since gravity limits the capillary ascent in a progressive ratio1 as shown in diagram #ci1 it is obvious that the true maximum saturation can exist only in a very short 7strictly speaking1 an infinitesimally short7 vertical column4 ,the least practicable height for experimental work being about #a cm4 7 in471 the writer has adopted for the purpose of rapid determination of this factor1 the use of a brass cylinder #a cm4 high and of such width as to contain1 for the sake of convenience1 #be or #ej cm4 of soil4 ,this cylinder has a finely perforated bottom1 which may be covered with filter paper2 after being filled with soil which has been struck level1 and weighing1 it is immersed to #a mm4 depth in distilled water and allowed to rest for an hour2 then quickly dried outside and beneath with filter paper1 and again weighed4 ,the amount of water found by difference should for all practical purposes be referred to the volume1 not to the weight1 of the soil1 so as to eliminate the error arising from the varying specific gravity of the latter4 ,in most cases the surface of the soil in the sieve cylinder remains level after wetting2 but sometimes it swells so as to rise above its dry level1 even to the extent of nearly #cj 7see chapter #g1 p4 #aad74 ,this happens especially in strongly ferruginous soils4 ,in the case of 8black alkali0 soils1 in wetting an enormous collapse sometimes takes place 7see chapter #bb74 ,if it be desired to determine also the minimum liquid absorption 7see below71 the surface of the wet soil is first covered with air-dry soil1 to absorb the surplus moisture1 and finally with soil previously saturated with hygroscopic moisture2 the added soil being each time thrown off and finally the surface 8struck0 level with a tense silk thread before weighing4 ,corrections must be applied for the usual increase in weight1 from the addition of soil1 and for the hygroscopic moisture4 ,while the minimum of liquid absorption can thus be determined quickly1 without awaiting the capillary ascent of a water column1 and if sufficient time is given can also be determined in higher columns1 as proposed by ,mayer 7,wollny's ,forsch4 ,vol4 #c71 the maximum cannot thus be determined without gross inaccuracy4 ,in determinations made by the writer it was found that the figures for the minima of very different soils 7clayey and sandy7 of the arid region1 differ proportionally much less than do the respective maxima4 ,in few of these soils it was found to exceed about #aj per cent1 and it scarcely fell below #d per cent even in very sandy soils4 ,a very deep1 sandy soil1 which had been irrigated in ,may1 and upon which no rain had since fallen1 showed in ,july in the second foot1 upon which rested ten inches of fully air-dried soil free from vegetation1 a water-percentage of eight per cent4#gh #gh ,hall 7,the ,soil1 p4 #ff7 gives for the minima in the case of soils examined by him the following figures3 coarse sandy soil1 #bb4b1 light loam1 #ce4d1 stiff clay1 #de4f1 sandy peat1 #eb4h4 ,these figures are very much higher than for apparently similar materials used by the writer1 and the differences exceed those between the maxima given for the same4 ,this discrepancy ,i am unable to account for4 ,capillary ,action in ,moist ,soils4--,in the preceding discussion the case of columns of air-dry soils1 so common in the arid regions1 has been considered4 ,it is obvious that a soil column holding the minimum of capillary water may be of any height2 so that when1 as happens in the open field1 the rain water soaks down beyond the range of capillary rise in a given soil1 the upper portions of the latter1 above that range1 will remain at the minimum of moisture-content so long as it is not depleted by evaporation4 ,king has made extended observations on soil columns ten feet high and moistened throughout the mass4 ,capillary movement takes place in moist soils much more rapidly than in dry ones1 although when sufficient time is given the final adjustment will of course be the same4 ,king's experiments showed that evaporation at the surface of the tenfoot columns caused a sensible depletion of the water content originally existing at the depth of ten feet1 in the course of #cad days4 ,while so slow a movement might not be of any benefit during the growth-period of shallow-rooted annual crops1 the fact shown is of importance to permanent plantings1 as of trees and vines4 ,another and not so readily intelligible effect observed by ,king is that when the surface-soil is wetted1 moisture may be withdrawn toward the surface from the lower layers4 ,in one experiment he found that when water was applied on the surface so as to add two pounds of water to each surface foot in several soils1 at the end of #bf hours there had been an increase of three pounds in the same1 and a loss of one and three quarter pounds from the second and third feet4 ,the cause of this translocation is probably a 8distillation0 of the subsoil moisture toward the cooled soil2 the fact that it occurs is of practical interest1 since it seems to show that wetting the upper portion of the soil by cold rain or irrigation may tend to raise additional supplies from below4 ,at the change of seasons we not uncommonly find1 in digging tree holes or wells1 a wet streak at from #i to #ah inches below the surface1 caused evidently by the condensation of subsoil moisture1 at the limit of a cold zone resulting from the penetration of unseasonable temperature 78cold snap07 from above4 ,such movements of soil-moisture by means of evaporation and recondensation within the soil can of course take place even when the minimum of liquid absorption has been reached and direct capillary movement has ceased4 ,it is1 as it were1 dew within the soil4 ,proportion of ,moisture ,available to ,growing ,plants4--,not all the capillary moisture contained in soils is available to plants1 as can readily be seen from the fact that many plants1 especially when growing in pots1 begin to wilt while the soil still appears visibly moist4 ,the limit of wilting differs greatly in different plants1 and in the open ground it is difficult to ascertain that limit1 because the deeper roots continue to supply moisture from moister substrata4 ,hence potted plants wilt while the soil appears much moister than when the same grow in the field4 ,king#gi has determined the amounts of moisture down to #dc inches in a ,wisconsin soil in which clover and corn were at the wilting point1 as in the following condensed table3 ,clover4 ,maize4 ,fallow ground4 ---------------------------------------- ---------------- ,first #ab inches1 clay loam #h4dd #g4jc #ag4ja ,second #ab inches1 reddish clay #ab4hd #aa4gi #ai4hf #bd to #cj inches1 sandy clay #ac4eb #aj4hd #ah4ef #dj to #dc inches1 sand #i4ec #d4ag #ae4ij ---------------------------------------- ---------------- #gi ,physics of ,agriculture1 p4 #ace4 ,it is plainly shown here that the roots of clover and corn were unable to utilize the higher moisture-content of the subsoil-clay to the same extent as the smaller amounts present in the surface foot1 and in the sandy substrata4 ,evidently the moisture in the clay soil was more tenaciously retained4 ,this is doubtless due1 as ,king shows1 to the equal thinness of the moisture film remaining on the soil grains in either case2 the number of grains1 and therefore the aggregate surface holding these films1 being much greater in the clay than in sands2 hence the higher water content4 ,it is interesting to compare these figures given by ,king for clover and maize at the wilting-point1 and fallow ground adjacent1 with those given by ,eckart 7,rep4 ,expt4 ,sta4 ,haw4 ,sugar ,planters' ,ass'n41 #aijc7 for those affording good growing conditions for sugar-cane on the 7highly ferruginous7 soils of that station4 ,the plots were irrigated at the rate of one1 two and three inches of water per week1 allowance being made for the rainfall4 ,two inches proved1 on the whole1 to give the best average results for production4 ,the moisture determination of the soil under the two-inch regime gave an average moisture content of #bi4ac in the first foot of soil4 ,it is not stated what was the hygroscopic coefficient of that soil1 but it was probably very high2 in the neighborhood of #ba4e1 judging by the determinations made with six ,hawaiian soils at the ,california ,station4 ,this would indicate about #g4fc of free moisture as the optimum for sugar-cane4 ,moisture-requirements of ,crops in the ,arid ,region4--,plants 7particularly broad-leaved ones7 which have made a brash growth during a period of abundant moisture1 will wilt quickly when sunshine returns1 and take some time to adapt themselves to the drier conditions4 ,on the other hand1 plants accustomed to dry air and scanty soil-moisture1 will not wilt or suffer under what would elsewhere be considered very rigorous conditions4 ,loughridge#hj has made numerous determinations of moisture in soils in which crops were beginning to suffer1 and others on similar soils that were growing normally1 and found that in general1 not only were the differences in moisture content considerably less than in the case above quoted from ,king's observations1 but that the amounts of free moisture required by various crops in the arid climate of ,california were surprisingly small4 #hj ,rept4 ,cal4 ,expt4 ,sta4 #ahig-jh1 pp4 #fe-if4 ,the tables below show the results of observations made by ,loughridge during several drought years in ,california2 so arranged as to show the differences of moisture content for the same crop in different soils4 ,it will be observed that in all cases where a crop growing on a clay soil could be compared with the same on a lighter soil1 the moisture required to keep the crop in good condition was very much greater in the clay than in the loam or sandy soils4 ,in the case of apples1 e4 g41 #h4c of water was abundant to keep the trees in excellent condition on a loam soil1 while on a clay soil holding #ab4c the condition was very poor4 ,that this difference is due in the main to the difference in the hygroscopic-moisture coefficient of the respective soils1 is plainly apparent in several cases4 ,it is therefore not the total moisture content1 but the free moisture present in excess of what is held by hygroscopic absorption1 that determines the welfare of the plant4 ,by determining1 first1 the total moisture in the soils1 as taken in the field1 then1 after allowing them to become air-dry1 determining the maximum of hygroscopic moisture they would absorb 7see p4 #aih71 ,loughridge found by difference the amount of free moisture1 or liquid water which must be present in the soil to prevent the crops from suffering4 ,an exceptionally good opportunity for these observations was offered by the dry season of #ahih1 during which crops suffering and not suffering1 on identical lands1 could easily be found4 ,the determinations were always made for each foot of the upper four feet of the land in the immediate neighborhood of the trees or among the field crops4 ,the first table exemplifies the method of procedure2 the second gives the summary of results for the several crops and trees1 as calculated from observations made during the season4 ,,table ,,showing ,,condition ,,of ,,crops ,,on ,,various ,,soils ,,under ,,different ,,moisture-,,conditions4 ,per cent ,moisture in four feet4 ,kind of ,kind of ,condition--------------------------- ,crop4 ,soil4 of ,tons ,crop4 ,total4,hygroscopic4,free4 per acre4 ---------------------------------------- --------------------- ,wheat ,very sandy ,poor #b4f #a4i 4#g #ef 8 ,sandy loam ,good #ab4h #e4f #g4b #egf 8 ,clay ,dead #ad4a #aj4e #c4f #bhh ,maize ,clay adobe ,very good #ab4i #h4h #d4a #cbh 8 ,sandy loam ,fair #f4a #b4c #c4h #cjd ,barley ,black adobe ,wilting #aj4g #h4h #a4i #aeb ,sugar ,beets ,black loam ,good #ab4d #e4f #f4h #edd ,vines ,loam ,good #h4e #e4j #c4e #bhj 8 ,sandy loam ,poor #a4i #a4e 4#d #cb ,almonds ,loam ,good #h4e #f4f #a4i #agh 8 ,same field ,suffering #g4i #f4i #a4j #hj ,apples ,loam ,excellent #h4c #e4e #b4h #bbd 8 ,clay ,poor #ab4c #aj4h #a4e #abj ,apricots ,loam ,excellent #f4c #c4c #c4j #bdj 8 ,gravelly loam,poor #f4i #e4j #a4i #aeb ,figs ,red loam ,good #e4b #c4h #a4d #aab 8 ,heavy loam ,wilting #h4f #h4f #j #j ,olives ,red loam ,good #e4b #c4h #a4d #aab 8 ,sandy loam ,suffering #a4i #a4i #j #j ,peaches ,red loam ,good #h4b #e4j #c4b #bef 8 8 ,poor #f4h #e4j #a4h #add ,prunes ,gray loam ,excellent #aa4b #i4j #b4b #agf 8 8 ,poor #f4d #e4d #a4j #hj ,citrus fruits,sandy loam ,good #f4c #c4a #c4b #bef 8 8 ,sandy soil ,leafless #c4a #b4d 4#g #ef ---------------------------------------- --------------------- ,,table ,,showing ,,drought-,,endurance ,,of ,,various ,,crops ,,in ,,arid ,,region4 ,free water in four feet of soil4 ,crops that did well in ,crops that suffered ------------------ lowest amount of in highest amount of ,tons moisture mentioned moisture mentioned ,per cent4 per in first column4 in first column4 acre4 ---------------------------------------- ----------------------- #j to #a4j #hj ,apricots1 ,olives1 ,grapes1,citrus1 ,pears1 ,peaches1 ,soy-bean4 ,plums1 ,acacia4 #a4j to #a4e #abj ,citrus1 ,figs4 ,almonds1 ,apples4 #a4e to #b4 #afj ,almonds1 ,plums1 ,saltbush4,barley4 #b to #b4e #agf ,prunes4 #bjj ,walnuts1 ,eucalyptus4 ,prunes4 #b4e to #c #bbd ,apples4 #c to #c4e #bhh ,pears4 #c to #d #cbb ,hairy ,vetch4 ,wheat4 #d to #e #djj ,wheat1 ,maize4 #e to #f #dhj ,sugar beets1 ,sorghum4 ,sugar beets4 ---------------------------------------- ----------------------- ,,chapter ,,xii4 ,,the ,,water ,,of ,,soils4--,continued4 ,,surface1 ,,hydrostatic ,,and ,,ground ,,water2 ,,percolation4 ,since all the water of soils and plants is directly or indirectly derived from the rainfall 7including therein snow and hail71 some general points regarding this factor require first consideration4 ,while it is not the object of this work to discuss climatology in detail1 yet the times of the year and the manner in which precipitation comes1 acts upon and is disposed of in the soil under different climatic conditions1 must of necessity form an essential part of its subject matter4 ,amount of rainfall4--,the rain falling in the course of a year is usually stated in the form of 8inches0 7or centimeters71 implying the height of the water column that would be shown at the end of the year had it all been allowed to accumulate2 or1 the sum of all the successive rains 7including snow7 observed during the year4 ,since this amount ranges all the way from nothing1 or a mere fraction of an inch 7as in portions of the ,andes1 and of the great ,african and ,asian deserts7 to as much as #fjj inches or fifty feet 7,cherapundji in eastern ,india71 the adaptation of agricultural practice to the maintenance of the proper moisture-supply to crops is largely a local question1 oftentimes of not inconsiderable difficulty4 ,this is especially the case where torrential rains1 yielding several inches of rain in a few hours1 alternate with light1 soaking rainfall1 as is very commonly the case in the interior of continents1 and more especially in the ,united ,states east of the ,rocky ,mountains4 ,westward of the same the rainfall decreases so rapidly that at or about the one-hundredth meridian 7the longitude of ,bismark and ,pierre1 ,dakota1 and ,dodge ,city1 ,kansas7 we already reach the annual average of #bj inches1 which is commonly assumed to be the limit below which crops cannot safely be grown without irrigation4 ,the 8cloudbursts0 occasionally occurring within these limits are usually confined to mountainous regions1 and the water they pour down on the dry soil is rarely of any direct benefit to agriculture2 hence they cannot be properly counted in the general estimate of the effective rainfall4 ,a region of high rainfall 7up to #ajj inches and over71 however1 extends along the ,pacific coast from northern ,california through western ,oregon and ,washington across ,british ,columbia to ,alaska1 to seaward of the ,sierra ,nevada1 ,cascade1 and ,alaskan coast ranges4 ,in the country east of the ,mississippi river1 the average annual rainfall ranges from #cj inches in the region of the ,great ,lakes1 and #de to #ej inches on the north ,atlantic coast1 to #fj inches in ,louisiana and up to eighty in southern ,florida4 ,the average of the ,mississippi ,valley and ,atlantic coast ,states is usually stated at about #de inches1 which is distributed more or less evenly throughout the year1 excepting usually from six to eight weeks of more scanty precipitation in the latter part of ,august and in ,september--the 8,indian summer0 season2 so that the winter is the season of greatest total rainfall4 ,natural disposition of the ,rain ,water4--,the rainfall is naturally first disposed of in two ways1 viz41 a portion which is absorbed by the soil1 and another which is at once shed from the surface and constitutes the 8surface runoff40 ,the portion absorbed into the soil is subsequently disposed of either by soakage downward into the subdrainage and through springs and seepage#ha into the streams and rivers2 or by evaporation4 ,the latter again occurs in two different ways1 viz41 from the soil-surface itself1 or through the roots and leaves of plants4 ,the importance of each of these modes is sufficiently great to entitle each to detailed consideration4 ,the ,surface ,runoff4--,this portion of the disposal of rain may range all the way from nothing to almost totality1 according to the nature of the soil and the condition of its surface4#hb ,sandy soils1 especially when coarse1 may absorb instantly even a very heavy rainfall4 ,heavy clay soils when dry will at first also absorb quickly quite a heavy precipitation2 but as the beating of the raindrops compacts the surface1 the absorption quickly slows down1 so that heavy downpours of brief duration1 while wetting thoroughly into a plastic mass the first two or three inches of a clay soil1 may leave all beneath dry1 to be very gradually moistened by the slow downward percolation against the resistance of the air in the soil2 while the greater part of the later portion of the shower will drain off the surface in muddy runlets4 ,certain soils classed as loams1 having the property of crusting readily by rain followed by sunshine 7see chapter #g1 p4 #aaa71 in heavy showers behave hardly better than strong clay soils2 shedding the water until the soaked crust gives way1 and is carried off in muddy streamlets4 ,then begins the cutting-away of the soil that1 in portions of the ,cotton ,states1 as well as north of the ,ohio river1 has been the cause of extensive devastation of once fruitful culture lands1 the site of which is now marked by 8red washes0 and gullies but too familiar to the eye in many regions1 especially of the southern ,united ,states4 #ha ,the quiet seepage from the banks and beds of streams plays a much more important part in the increase of volume of flow than is commonly supposed1 because unperceived save by measurement of the tributaries and comparison with the main streams4 ,this is especially true of the drainage in the arid region1 where the deep and pervious soils favor diffuse seepage as against definite spring flow4 #hb ,toumey 7,yearbook ,u4 ,s4 ,dep't ,agr4 #aijc7 states that in the ,san ,bernardino mountains in southern ,california1 the first rainfall 7in ,december7 was absorbed to the extent of #ie in forested areas1 against only #fj in the non-forested2 but that later1 after the soil had been partially saturated1 #fj only was absorbed in the forested land1 against #e in the non-forested4 ,while it is generally admitted that forests diminish the runoff1 ,rafter 7,relation of ,rainfall to ,runoff1 ,u4 ,s4 ,geol4 ,survey ,paper1 ,no4 #hj1 p4 #ec7 contends that in ,new ,york ,state the reverse is true4 ,illustration3 ,,fig4 #dj4--;,erosion in ,mississippi ,table ,lands1 causing destruction of agricultural value both of ,uplands and ,valleys4 7,mc,gee1 #abth ,ann4 ,rept4 ,u4 ,s41 #ahij-ia47 ,washing-away and ,gullying in the ,cotton ,states4--,nowhere perhaps have these effects been so severely felt as in portions of northwestern and central ,mississippi1 and this case is so instructive as to deserve a more detailed description4 ,in the regions in question the soil stratum consists of a yellow or brownish loam from three to seven feet in original thickness1 constituting a very desirable class of gently rolling uplands1 which at one time claimed to be the best cotton-growing portion of the ,state4 ,it was originally covered with an open forest of oaks1 with an abundant growth of grasses that afforded excellent pasture to deer and cattle2 a natural park gay with flowers during most of the season4 ,when these lands were taken into cultivation little or no attention was paid to the direction of the furrows and rows of corn and cotton2 most commonly the plowing was done 8up-hill and down10 so that the 8dead-furrow0 afforded a ready opportunity for the formation of washes cutting into the subsoil1 during the torrential rains sometimes falling during the summers4 ,even when filled with soil by plowing1 these washes would frequently re-open during rains1 shedding the soil in a muddy flood upon the lower lands4 ,the washing-away of the surface soil1 thus brought about1 of course diminished the production of the higher lands1 which were then commonly 8turned out0 and left without cultivation or care of any kind4 ,the crusted surface shed the rain water into the old furrows1 and the latter were quickly deepened and widened into gullies--8red washes0--whose presence rendered any resumption of cultivation difficult4 ,in the course of a few years the soil-stratum of brown loam was penetrated into the loose or loosely cemented sand which underlies it almost everywhere1 and is very readily washed away4 ,soon the water1 gaining yearly in volume1 undercut the loam stratum so as to cause it to 8cave0 into gullies in huge masses1 which with the sand were carried into the valleys adjacent1 filling the beds of the streams so as to cause their flow to disappear under the flood of sand4 ,as the evil progressed1 large areas of uplands were denuded completely of their loam or culture stratum1 leaving nothing but bare1 arid sand1 wholly useless for cultivation2 while the valleys were little better1 the native vegetation having been destroyed and only hardy weeds finding nourishment on the sandy surface4 ,illustration3 ,,fig4 #dj;a4--,erosion in ,mississippi ,table ,lands1 causing destruction of agricultural value both of ,uplands and ,valleys4 7,mc,gee1 #abth ,ann4 ,rept4 ,u4 ,s4 ,g4 ,s41 #ahij-ia47 ,in this manner whole sections1 and in some portions of the ,state whole townships of the best class of uplands have been transformed into sandy wastes1 hardly reclaimable by any ordinary means1 and wholly changing the industrial conditions of entire counties2 whose county seats even in some instances had to be changed1 the old town and site having1 by the same destructive agencies1 literally 8gone down hill40 ,this destruction of lands was greatly aggravated by the civil war1 during which1 and for some time after1 large areas of lands once under cultivation were left to the mercy of the elements4 ,injury in the arid regions4--,in the arid regions1 where the rainfall frequently comes in heavy downpours or 8cloudbursts10 immense damage to pasture lands has been brought about by overstocking1 in ,arizona and ,new ,mexico2 involving the destruction of the natural cover of vegetation and the loosening of the surface especially by sheep2 after which a heavy rainfall will carry off the surface soil1 the muddy water being gathered largely in the trails made by cattle going to water4 ,thus gradually gullies are formed1 which enlarging more and more become ravines and cut up the pasture slopes into 8bad lands10 useless equally for pasture and for agriculture4#hc ,california1 eastern ,oregon and ,washington1 and ,montana1 offer striking and lamentable examples of the same destructive agencies4 #hc ,open ,range and ,irrigation ,farming4 ,r4 ,h ,forbes1 in ,forester1 ,nos4 #g1 #i1 #aijb4 ,deforestation4--,the deforestation of hill and mountain lands has1 the world over1 led to similar results2 causing not only the destruction of pasture and agricultural lands1 but also the conversion of streams1 flowing from springs and seepage all the year1 into periodic torrents1 flooding the lowlands during rains by the rapid running-off of the water from the bare and hard-baked mountain slopes1 and then running dry within a short time1 so as not even to afford drinking water to pasturing cattle in summer4 ,thus for half a century the unsolved problem of the 8correction of the waters of the ,jura mountains0 was before the ,swiss and ,french governments2 and the great and costly public work involving re-forestation1 deflection of torrents and filling-in of deep ravines and gullies1 is not even yet nearly completed4 ,in ,spain1 which in the time of the ,roman occupation was largely a forest country with abundant rainfall1 the same results are seen1 notably in the ,south1 in the wide1 and mostly dry1 sandy beds of streams once running deep and clear2 and in the scarred hill-and mountain-sides1 and scant vegetation of low shrubs 78chaparral07 that replace the once abundant tree growth1 e4 g41 in ,old and ,new ,castile4 ,unfortunately the lessons taught by the bitter experience of the old world seem to require actual repetition in the new1 before means of prevention are even thought of4 ,prevention of ,injury to ,cultivated ,lands from excessive ,runoff4--,the fundamental remedy for the injurious effects of excessive runoff from the land surface is1 of course1 to facilitate its absorption into the soil to the utmost extent possible1 by deep tillage2 or in cases where this is undesirable 7as when in rainy climates excessive leaching of the land is feared71 to so direct and control the surface drainage that its flow shall nowhere be so rapid as to carry with it any large amounts of earth1 or to wash out the furrows4 ,to this end its fall must be diminished by 8circling10 i4 e41 plowing nearly at right angles to the slope instead of up-and-down1 and on steep slopes especially also by maintaining open furrows or ditches having a gentle fall only1 into which the water can shed and flow off quietly in case the furrows1 left in plowing1 prove insufficient to retain and shed gradually the water they cannot hold permanently4 ,the early adoption of this simple expedient would have wholly prevented the enormous waste of fine agricultural lands referred to above4 ,the underdraining of lands liable to washing is a costly but highly effective means of preventing denudation2 and the laying of underdrains in gullies already formed1 to prevent farther deepening1 is among the most obvious means of arresting farther damage4 ,the beneficial effects of underdrainage in conserving moisture will be discussed farther on4 ,,absorption ,,and ,,movements ,,of ,,water ,,in ,,soils4 ,the phenomena and laws of capillary ascent of water in soils1 as discussed in the preceding chapter1 serve best to demonstrate the general behavior of liquid water within different soils and their several grain-sizes2 because measurably independent of the physical changes that almost unavoidably accompany the percolation of water from above downward2 whether such water comes in the form of rain1 or irrigation1 or even when applied with the utmost precautions in the laboratory4 ,the 8beating0 of rains quickly compacts the surface to a certain extent1 varying with the nature of the soil1 its condition of more or less perfect tilth1 and the degree of violence with which the rain strikes the surface4 ,when the latter has been compacted by a previous rain and then dried1 8baking0 or incrusting the surface1 the latter may almost wholly shed a rain of brief duration1 which1 had the surface been loose1 would have been wholly absorbed1 materially benefiting the crop4 ,such surface-crusting is1 therefore1 injurious in preventing the absorption of water from above2 and in addition1 it serves to waste1 by evaporation1 the moisture contained in the underlying soil and subsoil4 ,for the crust being of a finer 7single-grain7 texture than the tilled portion beneath1 it will forcibly abstract from the latter1 by absorption1 its capillary moisture1 and evaporating it at the upper surface1 continue to deplete the land1 to the great injury of crop growth1 until destroyed by cultivation4#hd #hd ,this effect is well illustrated by the behavior of a dry brick laid upon a wet sponge4 ,it will quickly absorb all the liquid moisture contained in the latter1 while the sponge will be wholly unable to take any moisture from a fully-soaked brick4 ,the flow of irrigation water produces the same compacting effect1 but to a less extent2 the more as1 unlike rain water1 irrigation water usually contains a certain amount of alkaline and earth salts1 which tend to prevent the diffusion of clay and of fine sediments1 and therefore the disintegration of the soil-floccules into single grains4 ,nevertheless1 it is in some soils as necessary to cultivate after surface-irrigation as after rains1 in order to prevent great waste of moisture by evaporation4 ,determination of rate of percolation4--,when water is allowed to soak into an air-dry soil column without sensible shock or motion1 from a constant level1 we obtain the nearest approach to a definite determination of the relative permeability of soils to water under the conditions usual in the arid region4 ,a number of determinations thus made is tabulated in the diagram given below1 which embodies the observations made by ,mr4 ,a4 ,v4 ,stubenrauch#he in connection with a more extended investigation4 #he ,rep't ,calif4 ,exp't ,station for #ahih to #aija1 p4 #afe4 ,as these experiments were made with soils not in their field condition1 but gently broken up with a rubber pestle1 a standard of compactness was established by weighing the quantity which could conveniently be settled into a tube space of #ajj centimeters capacity by tapping the sides and bottom of the tube1 without touching the soil itself4 ,in this way the following standards were established3 ,for the ,university ,adobe soil1 #adj grams2 for the ,yuba loam soil1 #aaj grams2 for the ,stanislaus sandy soil1 #agj grams4 ,tubes #a inches wide were used1 and the soils were introduced in bulk1 inside of a cylinder of stiff paper upon which previously to rolling it up the soils had been thoroughly mixed4 ,after introducing the soil-filled paper roll it was gently withdrawn1 leaving the soil column in the tube as uniform as before2 a condition almost impossible of fulfilment when the soil is introduced piece-meal4 ,the tubes were1 of course1 left open at the lower end1 using a wire netting to keep the soil column in1 so that the air could escape freely before the descending water column4 ,the results thus obtained do not1 of course1 apply directly to the same soils undisturbed in place in the field2 where1 moreover1 the air is confined by the wetting of the surface and thus directly opposes penetration of the water4 ,still1 they doubtless give a correct idea of their relative permeability for water when in the tilled condition4 ,the water level was automatically maintained at the depth of half an inch above the surface of the soil columns4 ,pore-spaces given are calculated from volume-weight and specific gravity4 ,this diagram shows plainly that there is no direct relation between the total pore-space in a soil and the facility of water-penetration4 ,the highest pore-space1 in the fine-grained alluvial loam1 allows more rapid percolation than the heavy clay or adobe soil1 but is greatly exceeded by the coarser sandy soil4 ,in all it is very apparent that the downward movement slows down as the water descends1 doubtless because the great friction in a longer column gradually diminishes the effect of hydrostatic pressure4 ,it may be presumed that at a certain distance from the surface the downward movement becomes practically uniform1 and independent of the pressure from above4 ,illustration3 ,,fig4 #da4--;,diagram showing differences in rates of percolation through different soils4 ,summary4--,two salient points are revealed by even a cursory inspection of the preceding diagram1 viz43 #a4 ,the downward percolation is most rapid in the same soils in which the capillary ascent is quickest1 that is1 in the coarse1 sandy soil4 #b4 ,the rapidity of percolation decreases materially as the wetted soil column increases in length4 ,the first point is readily foreseen and needs no comment4 ,as regards the second1 it results from the fact that as the wetted column lengthens the frictional resistance increasingly counteracts the effects of the hydrostatic pressure from above1 until the water's descent becomes but little more rapid than would be its lateral diffusion1 or its ascent at the end of a similar column supplied by capillary rise from below4 ,in both cases the frictional resistance has so far counteracted the effect of gravity that the capillary coefficients of the soil-material become the controlling factors of the water movement4 ,influence of ,variety of ,grain-sizes4--,king 7,physics of ,agriculture1 pp4 #aei1 #afj71 compared the rapidity of the percolation of water through definitely graded pure sands on the one hand1 and a sandy loam and a clay soil on the other4 ,the materials were arranged in #h-;foot columns fully saturated with water at the outset1 and then allowed to drain freely4 ,the following abridged table shows the tenor of his results3 ,,table ,,showing ,,relative ,,rapidity ,,of ,,percolation ,,in ,,pure ,,sands ,,and ,,soils1 ,,in ,,inches ,,of ,,water ,,drained ,,off4 ,diameter of ,uniform ,first ,second ,total ,sand ,grains4 #cj minutes4 #cj minutes4 in one hour4 ---------------------------------------- ----------------------- 4#dge mm4 #aj4be #d4fh #ad4ic 4#aee 8 #e4fg #d4eb #aj4ai 4#jhc 8 #a4ba 4#he #b4jf ,first #ba-bc ,first #aj ,second #aj ,total in ,soils4 hours4 days days about following4following4 #eje hours4 ---------------------------------------- ---------------------- ,sandy loam #b4fd #e4jg 4#ia #h4fb ,clay loam #a4if #b4aa 4#di #d4ef ---------------------------------------- ---------------------- ,this table is very instructive in showing the great difference in the rapidity of percolation in materials of uniform1 even-sized grains1 as compared with such as contain particles of many different sizes1 in which the interspaces of the larger ones are filled more or less closely by the smaller sizes of particles 7see chapter #g1 p4 #aji74 ,while it is true that we have no definite physical analysis of the soils here used1 the differences are so great as to be sufficiently striking4 ,compare the percolation through the sand of 4#aee mm4 uniform grain-size 7a fine sand71 during the first half hour1 with that through the sandy loam during the first #ba hours4 ,twice as much water has passed from the sand as from the soil in one forty-second part of the time4 ,comparing similarly the finest sand1 4#jhc mm4 in diameter1 with the clay loam1 we find the difference to be as one to seventy-three4 ,it is thus evident that but for the variously assorted sizes of the soil-particles1 water would not be held long enough to supply plant growth4 ,percolation in ,natural ,soils4--,in artificial percolation experiments1 as well as during a fall of rain1 the gradual settling of the fully wetted soil-column produces a compacting of that portion of the mass1 that increasingly impedes the downward penetration4 ,the effect of this under natural conditions is readily seen in the fact that after the first1 rapid absorption of falling rain by the soil when in good tilth1 there is a gradual slackening of the process even when the rain is fine and slow1 causing a perceptible increase of the runoff until1 should the rain continue for some time1 the absorption becomes so slow as to cause all1 or nearly all the water to drain off the surface4 ,the soil is then called 8saturated10 having really arrived at that point right at the surface1 and to a depth varying according to the duration and amount of rain1 and the natural perviousness of the land4 ,when the rain ceases1 the visible saturation of the surface usually soon disappears in cultivated soils1 and the zone of saturation begins to descend4 ,the progress of this descent may be very strikingly observed in a series of holes 7post-holes7 dug or bored across a ridge2 as indicated in the subjoined schematic diagram1 in which the successive dotted lines represent the levels of the descending 8bottom water0 at successive intervals1 as derived from the observation of the water levels in the several holes4#hf #hf ,the exact record of these observations was unfortunately destroyed by fire2 the soil was a heavy clay1 and it took ten days before the water disappeared from the lowest hole4 ,illustration3 ,,fig4 #db4--,percolation in clay land after heavy rain4 ,it will be seen that while at first the upper surface of the zone of saturation coincides with the surface of the ground1 in falling it descends most rapidly on the highest ground1 while at the lower levels the holes may remain full or overflowing2 the drainage taking place sideways as well as vertically4 ,the curved surface connecting the levels in the several holes gradually flattens1 rapidly at first1 then progressively more slowly2 the water disappearing entirely1 first from the holes lying highest1 then successively from those at lower levels2 those located in valleys or drainage channels remaining full until surface-water ceases to run in such channels4 ,but even after liquid water has ceased to be visible in the holes1 the descent of the water continues within that portion of the soil1 tending 7unless more rain should come before that time71 to establish the condition of equilibrium as existing in the soil columns shown in the diagram on p4 #bje1 chapt4 #aa2 such as results from the capillary ascent of water from below1 but having above it a column of soil of minimum water-content1 of greater or less height according to the length of time allowed for the water to descend4 ,this is a very common state of things during the long summer droughts in the arid region1 when neither rain nor irrigation has added to the water supply in the soil for many months1 and yet ordinary deciduous fruit trees mature their normal crops4 ,frequently1 however1 before this state of equilibrium is reached1 evaporation from the surface so draws upon the water supply within the first few feet1 as to reduce the soil to undersaturation at the lowest point of the descending column1 so stopping farther descent and soon reversing the direction of the movement4 ,the latter is the usual condition of scantily irrigated ground4 ,ground or ,bottom ,water1 ,water ,table4--,during and after long-continued and abundant rains1 the zone of supersaturation continues to descend until it finally reaches a more or less permanent level1 varying somewhat from season to season1 but on the whole usually definable for each region and locality2 being the depth to which wells must be sunk in order to secure a fairly permanent water supply4 ,this is called the water table1 ground water1 bottom water1 or 8first water40#hg ,the proportion of the rainfall that reaches the permanent water level varies enormously1 of course1 in different soils and at different times4 ,with brief and moderate rains1 in soils of high water-holding power and slow percolation1 it may never reach the bottom-water level2 this is very commonly the case in the arid regions4 ,where1 as in the humid regions1 rains are frequent or much prolonged1 one half and even more may finally reach the permanent level2 runoff and evaporation disposing of the balance4 #hg ,in contradistinction to other levels or 8streams0 of water which may usually be found lower down1 separated from the first water by some impervious stratum of clay1 hardpan or rock1 and very commonly under sufficient pressure to rise somewhat higher than the point at which it was struck1 owing to connection with higher-lying sources of supply4 ,when such pressure is sufficient to cause an overflow at the surface of the ground1 we have 8,artesian0 water as commonly understood4 ,lysimeters4--,for the determination of the amount of water percolating to given depths1 water-tight receptacles called lysimeters are usually employed4 ,the best way to establish such receptacles is to isolate a unit-area 7usually a square meter7 by digging all around it to the depth desired1 then surrounding it with a metal sheet soldered tightly at the cut edges1 and finally driving in a sharp-edged1 stiff metal sheet so as to form the bottom when soldered to the upright walls2 leaving on one side an outlet for the percolating water1 which is then received into a measuring receptacle somewhat like a rain gauge4 ,hall 7,the ,soil1 p4 #ge7 states that at ,rothamstead1 where an average rainfall of #ca4c inches is distributed rather uniformly through the season1 and where the soil is a moderately clayey loam1 a little less than half percolates through #bj inches of soil1 and about #de through #fj inches4 ,surface of ,ground ,water2 ,variations4--,the surface of the water table1 however1 is rarely level except in level and very uniform ground1 or after long periods of drought4 ,the undulations of its surface conform1 in general1 to that of the ground surface1 but are less abrupt2 so that the water lies nearer to the surface in low than in high ground1 as is indicated in the diagram above4 ,king#hh has shown1 moreover1 that the level of the ground water shows sensible variations due to increased or diminished barometric pressure1 as well as to variations of temperature in the soil1 which cause the air in the pores to expand or contract to a degree sufficient to bring about variations in the flow of springs and underdrains to the extent of #h and #ae respectively1 in conformity with the daily changes of temperature and pressure4 #hh ,physics of ,agriculture1 p4 #bgj4 ,the ,depth of the ,ground ,water most ,favorable to ,crops cannot be stated in a general manner1 as it depends materially upon the nature of the crop1 its root habit1 and the nature of the soil4 ,as has already been said1 the amount of soil-moisture most favorable to plant growth is about half of the maximum it can hold2 and this condition1 as is shown in the table in chapter #aa1 p4 #bjh1 is reached about the middle of the maximum height to which the water can rise by capillarity from the water level4 ,below this point the access of air to the roots becomes too limited1 and in case of continuous rains the root-ends would soon begin to suffer from want of aeration4 ,on 8sub-irrigated0 land1 therefore1 which is generally considered desirable1 crops must be carefully selected with respect to their root habits4 ,thus while alfalfa needs considerable moisture to do its best1 its deep-rooting habit renders it undesirable when the ground water is at less than five feet depth2 but red clover may be grown even with the water level at three feet4 ,in clayey soils root-penetration is always less than in sandy lands2 and although in the former the capillary ascent of water goes higher than in the latter1 yet its movement in clays is so much slower than in sandy materials that unless water is within comparatively easy reach1 the plants may suffer from drought4 ,experience has long ago fixed the proper depth at which to lay underdrains limiting the rise of bottom water1 at from three to four and a half or even five feet in clay soils2 greater depths are only exceptionally used1 partly because the laying of drains then becomes too expensive4 ,a mass of four feet of clay-loam soil is commonly1 then1 considered as sufficient to supply the needs of a crop2 it being understood that in the humid region at least1 such soils are usually the richest in plant food1 so that a deeper range of the root system is not called for4 ,it is quite otherwise in the sandy soils of the same region1 which being usually poor in plant food1 must afford a deeper penetration in order that an adequate amount of the same shall be within reach of the roots4 ,sandy lands1 then1 should be deep in order to repay cultivation2 and fortunately this is usually the case4 ,but when this is otherwise2 when for instance a sandy soil four feet in depth is underlaid by impervious clay1 underdrains may be quite as necessary as in the clay lands2 since the depth of actually available soil mass would otherwise be reduced to two or two and a half feet only1 by the water stagnating on the clay surface and rising from #af to #bd inches in the sand4 ,soils thus shallowed can with difficulty be maintained in good productive condition even by the most energetic fertilization4 ,moisture supplied by tap roots4--,in most cases1 sandy lands do not require underdraining2 and in them1 root-penetration may reach to extraordinary depths in the case of certain plants1 especially when taprooted4 ,thus the roots of alfalfa 7lucern7 are very commonly found to reach depths of twenty to twenty-five feet1 and even sixty feet has been credibly reported for the same plant in the arid region4 ,it is obvious that for such plants1 a high level of bottom water is wholly undesirable1 since they are enabled to obtain their moisture supply from great depths1 and can thus utilize for their nutrition much larger soil-masses than can shallow-rooted plants4 ,reserve of ,capillary ,water4--,it must be remembered that it is not only1 nor usually1 the bottom water that supplies moisture to plant growth2 for all soils of proper texture for cultivation retain within them a certain amount of capillary moisture after the ground water has reached its permanent level 7see this chap4 p4 #bbf71 and when the tap or main roots are plentifully supplied with water1 the upper and chief feeding roots draw but lightly upon the moisture within their immediate reach for the purpose of leaf evaporation4 ,this fact can be plainly observed in the arid region1 when on the advent of the summer drought1 young plantlets whose tap roots have reached a certain depth continue to flourish and develop1 while others practically of the same age1 but slightly behind1 quickly succumb1 though the feeding roots of both may draw upon the same soil layer4 ,it is especially in sandy soils that moisture is naturally thus conserved in the upper layers1 because of the failure of the water to rise by capillary ascent so as to evaporate from the surface layer4 ,it is often surprising to find a good amount of moisture in the sandy soils of desert regions at the depth of eight or ten inches1 when the surface is so hot as to scorch the fingers2 and this moisture continues very uniformly to great depths1 probably to bottom water lying twenty or more feet below the surface1 which in such materials may readily be reached by taprooted plants such as the 8sagebrush0 7,artemisia tridentata71 the saltbushes 7,atriplex7 and others4 ,injurious ,rise of ,bottom ,water resulting from ,irrigation4--,in the deep1 pervious sandy lands of the arid region1 especially where the rainfall is very low and can wet the soil annually only to two or three feet depth1 the substrata are sometimes found to be barely moist to depths of thirty and forty feet1 and the short-lived spring vegetation carries off during its growth all the moisture supplied by the winter rains4 ,when such lands are subjected to irrigation and the ditches carrying the water are simply dug into the natural sandy land1 the thirsty soil absorbs the water greedily1 so that even a considerable volume of water makes but slow progress toward the farther end of the canals4 ,gradually1 as the rapidity of absorption decreases1 the diminution of flow becomes less sensible1 but still the loss thus experienced may be a very considerable percentage of the whole supply4 ,thus in the ,great ,valley of ,california1 as well as in portions of ,wyoming 7,bull4 #fa1 p4 #cb71 the permanent loss from seepage is in the case of some extensive irrigation systems estimated at fully #ej per cent4 ,when such lands have a considerable slope1 the injury commonly ends with the loss of the water1 which in many cases is again gathered and utilized at a lower level4 ,but when the lands have but a slight slope1 the drainage may become so slow as to permit of the gradual rise of the seepage water in the substrata1 until finally it may come to within a few feet of1 or actually to the surface4 ,consequences of the ,swamping of ,irrigated ,lands4--,the injurious consequences of this swamping of the irrigated lands may readily be imagined4 ,the first effect is usually noted in the sickening or dying-out of orchards and vineyards1 consequent upon the submergence of the deeper roots1 which in such lands frequently reach to from fifteen to twenty feet below the surface4 ,but even where pre-existing plantations are not in question1 the shallowing of the soil- and subsoil-strata from which the plants may draw their nourishment1 constitutes a most serious injury to the cultural value of the land4 ,it has become unsuited to deep-rooted crops2 and where the natural soil1 alone1 would have perpetuated fertility for many years1 fertilization becomes necessary within a short time4 ,the injury becomes doubly great when1 as is frequently the case1 the rising bottom water brings up with it to the surface soil the alkali salts which previously were distributed throughout many feet of substrata1 frequently rendering profitable cultivation impossible where formerly the most luxuriant crops were grown4 ,theoretically of course it is perfectly easy to avoid or remedy these troubles4 ,it is only necessary to render the ditches water-tight by puddling with clay1 cement1 or otherwise4 ,but the heavy cost of this improvement forms a serious obstacle to its adoption by the ditch companies who are not themselves owners of land4 ,thus1 extensive areas of lands which when first irrigated were among the most productive1 have in the course of eight or ten years become almost valueless to their owners1 to whom legislation thus far affords but distant promise of relief2 although the case seems in equity to fall clearly within the limits of the laws governing trespass4 ,permanent ,injury to ,certain ,lands4--,in cases like those alluded to the remedy usually available for higher ground-water does not always afford relief1 even when otherwise available4 ,long-continued submergence produces in many soils effects which cannot easily1 if at all1 be overcome by subsequent aeration4 ,this is most emphatically true of soils containing a large proportion of ferric hydrate in the finely divided form in which it is usually present in 8red0 soils4 ,the first effect of the stagnation of water in such lands 7as already explained in a former chapter #c1 p4 #de7 is to set up a reductive 7bacterial7 fermentation of the organic matter of the soil1 transforming the ferric into ferrous hydrate1 which in the presence of the carbonic acid simultaneously formed1 becomes ferrous carbonate1 readily soluble in carbonated water4 ,that this compound is poisonous to plant growth1 has been stated 7chap4 #c1 p4 #df74 ,the carbonates of lime and magnesia are simultaneously dissolved by the same1 as is also calcic phosphate1 the usual form in which phosphoric acid is present in the soil4 ,under the influence of partial aeration from the surface1 the ferrous carbonate is slowly re-transformed into ferric hydrate1 aggregated in the form of spots or concretions of 8bog ore0 7see chapter #e1 p4 #ff74 ,in this process the greater part of the phosphoric acid of the soil is also abstracted from its general mass and concentrated in the bog ore 7chap4 #e1 p4 #fe71 in which it is wholly unavailable to vegetation1 and cannot be made available while in the ground1 by any known process4 ,the soil is therefore permanently impoverished in phosphoric acid2 it is also deprived of its content of ferric hydrate1 and is transferred from the class of 8red0 to that of 8white0 soils1 well known everywhere to be unthrifty and to require early fertilization4 ,not only is this true1 because of their almost invariable poverty in phosphoric acid1 but also usually in lime1 which like the iron1 if not leached out1 is aggregated into concretions in the subsoil1 leaving the surface soil depleted of this important ingredient4 ,the humus1 also1 is either destroyed or at least 8soured0 at the same time4 ,reduction of ,sulfates4--,should such a soil contain any considerable amount of sulfates1 especially in the form of gypsum or calcic 7or magnesic7 sulfate1 the reductive process results in the formation of iron pyrite 7ferric sulfid1 chap4 #e1 p4 #ge72 while at the same time the soil is often sufficiently impregnated with sulfuretted hydrogen as to be readily perceived by the odor1 or by the blackening of a silver coin4 ,this is very commonly the case in sea-coast marshes1 where a hole made with a stick thrust into the mud will be found to give forth both carburetted and sulfuretted hydrogen1 while a careful washing of the soil will reveal the presence of minute crystals of iron pyrite4 ,hence the need of prolonged aeration of marsh soils1 effecting the peroxidation of the ferrous compounds1 and the conversion of the pyrite first into ferrous sulfate1 and subsequently into innocuous1 yellow1 insoluble ferric oxy-sulfate4 ,ferruginous ,lands4--,the injurious effect of the swamping of ferruginous lands has been especially conspicuous in some of the irrigated rolling lands of the ,sierra ,foothills of ,california1 where orchards planted in relatively low ground and in full bearing have succumbed to the poisonous effects of the ferrous carbonate formed in the subsoil1 long before the water had risen so high that1 had the trees been grown afterwards1 they would have adapted their root system to the existing conditions and fared moderately well at least4 ,underdrainage of the lower lands is1 of course1 the only possible remedy for this state of things1 although even then the root-penetration is much more restricted1 and therefore natural fertility of much shorter duration1 than would have been the case without the rise of the irrigation water4 ,it is thus clear that in the practice of irrigation1 the liability of injury to the lower ground by 8swamping0 through the rise of the ground water should always be kept in view2 that1 in fact1 irrigation and provision for drainage should always go hand in hand4 ,the legal provisions facilitating the rights-of-way for irrigation ditches should be made equally cogent with respect to drainage4 ,,chapter ,,xiii4 ,,water ,,of ,,soils 7,continued74 ,,the ,,regulation ,,and ,,conservation ,,of ,,soil ,,moisture4 ,in view of the commanding importance of an adequate supply of water to vegetation1 the possible and available means of assuring such supply by utilizing to the best advantage both rainfall and irrigation water1 require the closest consideration4 ,loosening of the ,surface4--,the first thing needful1 of course1 is to allow the water free opportunity to soak into the soil1 so as to moisten the land as deeply as possible4 ,that to this end the surface should be kept loose and pervious by tillage1 breaking up crusts that may have been formed by the beating of rains1 has already been discussed4 ,in the case of heavy clay soils1 however1 this alone is not always sufficient4 ,the most effectual way to loosen the land to greater depths than can be reached by tillage1 is by means of underdrains laid at the greatest depth that is practically admissible4 ,effects of ,underdrains4--,that drain tiles laid for the express purpose of carrying off surplus water should help to conserve soil moisture1 seems at first sight to be a paradox4 ,yet the explanation of the fact1 which has been demonstrated by long experience1 is not difficult4 ,the effect is most striking in clay soils1 for sandy soils are commonly naturally underdrained already4 ,in discussing the changes of volume which soils undergo in wetting and drying1 the fundamental points in the premises have already been mentioned 7see chap4 #g1 p4 #aab74 ,clay soils in drying shrink considerably1 and re-expand on wetting1 but rather slowly2 moreover1 some clays crumble when wetted after drying1 while others1 very plastic when wet1 crumble on drying 7see chap4 #g1 p4 #aaf74 ,it follows that while a clay subsoil when kept permanently wet1 will form a uniform1 pasty1 difficultly penetrable mass3 when subjected to frequent alternate wetting and drying1 it becomes fissured and crumbly1 so as to resemble in its texture a tilled soil4 ,this frequent alternation of wetting and drying is precisely what1 in the course of time1 is brought about by underdrains2 rendering clay subsoils pervious both to air and water4 ,the consequence is that even heavy rains can be fully absorbed by the soil mass lying above the drains1 the surplus draining off readily in a short time4 ,roots therefore can not only penetrate1 but exercise their vegetative functions perfectly at the full depth of the drains4 ,they are still at liberty to penetrate as much deeper as their demands for moisture may require2 but the depth of four to four and a half feet is already so much greater than in the humid region would usually be reached by them in undrained clay soils1 that commonly the moisture successively retained within that mass is as much as is required by them during the growing season4 ,at the same time1 their feeding roots are so far below the surface1 that ordinary short droughts do not reach them at all2 while the underdrains prevent any injurious stagnation of water around them4 ,it need hardly be added that the entire task of cultivation is also greatly facilitated2 not only because drained soils can be plowed within a few hours after the cessation of rains1 as against the same number of days that would have to elapse in the undrained areas2 but because tillage is easier1 and less draft is required1 even when it is carried to a much greater depth4 ,underdrainage1 then1 must be counted as being among the most effective means both of utilizing the rainfall so as to prevent loss from runoff and injury from washing1 and of creating a deep1 loose1 pervious soil mass1 well adapted to root penetration as well as to the conservation of moisture2 rendering possible timely tillage and cultivation1 and early development of crops fully supplied with moisture and therefore secure against loss from drought4 ,the safety and improvement of crops thus secured corresponds in the humid region to that brought about by the command of irrigation water in the arid countries4 ,but it by no means follows that underdrainage can therefore be dispensed with in the latter1 or irrigation in the former4 ,both have their proper place in both regions2 but from special causes underdrainage1 as has already been stated1 should be widely used in irrigation countries to prevent the injuries otherwise but too likely to arise from over-irrigation 7see chap4 #ab1 p4 #bca74 ,winter ,irrigation4--,in many regions where irrigation is desirable but not absolutely necessary in ordinary seasons1 or where irrigation water is scarce in summer1 much advantage is gained by insuring thorough saturation of the land during the latter part of winter1 especially when spring or summer crops are to be sown4 ,the not inconsiderable time required for water to reach its permanent level or the country drainage in most soils1 often insures the retention of a certain surplus over what the soil can permanently hold1 within the period when it can be utilized by growing crops2 whose roots moreover are more likely to penetrate deeply in land where there is a steady increase of moisture as they descend1 than when the contrary condition is encountered4 ,the use of winter flood-waters to saturate the land is therefore in many cases the saving clause for a dry season4 ,,methods ,,of ,,irrigation4#hi ,the manner in which irrigation water is supplied to land and especially to growing crops exerts such a potent influence not only upon the welfare of the plants but also upon the condition of the land1 that a brief discussion of this topic seems necessary4 ,the following methods are in use to a greater or less extent3 #a4 ,surface sprinkling4 #b4 ,flooding4 ,a4 ,by lateral overflow from furrows or ditches4 ,b4 ,by the 8check0 system4 #c4 ,furrow irrigation4 #d4 ,lateral seepage from ditches4 #e4 ,basin irrigation4 #f4 ,irrigation from underground pipes4 #hi ,only a general outline of the principles of this subject is given in this volume2 special works must be consulted for working details4 ,among these the volume by ,king on 8,irrigation and ,drainage0 gives probably the most comprehensive presentation of the subject for both humid and arid climates4 ,also bulletins of the ,u4 ,s4 ,dep't of ,agriculture4 ,surface ,sprinkling4--,this method seems to be the closest imitation of the natural rainfall2 and yet it is in practice about the most wasteful and least satisfactory of all4 ,it is difficult of application on any large scale1 from obvious causes2 on the small scale1 in gardens and on lawns1 its disadvantages become amply apparent4 ,as usually practiced1 from a rose spout or spray nozzle1 the water falls much more abundantly than in the case of any desirable rain1 within the short time allowed by the patience of the operator4 ,if continued for a sufficient length of time to soak the soil to the desirable depth1 it compacts the surface of the ground so as to render subsequent tillage indispensable4 ,to avoid this1 amateur gardeners usually restrict the time of application1 repeating the same at frequent intervals1 sometimes daily4 ,the result is that the very slight penetration of the water either fails to reach the absorbent roots1 so that it is of little use to them1 and is evaporated by the next day's sun or wind2 or else it tends to draw the roots close to the surface1 where1 unless the application of water is actually made daily1 they are sure to suffer from the first intermission of the daily dose4 ,in actual practice the sprinkling method is therefore both inefficient and wasteful of water1 and exposes the plants to grave injury from any cessation of the water supply4 ,flooding presupposes land either level or only slightly sloping naturally1 or rendered so artificially2 usually by means of the plow and horse scraper4 ,flooding by lateral overflow from large furrows1 or ditches1 is very commonly practiced where the water supply is abundant and large areas1 such as alfalfa or grain fields1 are to be irrigated4 ,the overflow is regulated by portable check-boards1 proceeding from the highest points to the lowest1 and leaving each temporary dike in place until the ground is adequately soaked or the water reaches the next furrow below4 ,in heavy ground the operation may have to be repeated to insure proper depth of percolation4 ,check flooding necessitates more careful leveling1 and the throwing up of small dikes1 either temporary or permanent4 ,the costliness of the earth-work restricts the use of this method materially1 and the inconvenience caused in tillage by the dikes is objectionable1 especially in large-scale culture4 ,for the case of alfalfa fields1 which remain permanently set for a number of years1 it is however the largely preferred method4 ,in the case of field cultures1 the consolidation of the surface that follows flooding on the heavier soils renders subsequent tillage necessary in all but very sandy soils2 and hence it should always precede broadcast sowing4 ,one disadvantage of the surface flooding system is the slow penetration of the water caused by the resistance of the air in the soil to downward displacement2 its buoyancy acting directly contrary to the percolation of the water4 ,in close-grained1 heavy soils this objection is very serious1 on account of the loss of time involved when the irrigator's time is limited4 ,on sandy lands the air bubbles up quite livelily at first1 but this soon ceases and the air is compelled to escape sideways as best it can4 ,furrow ,irrigation4--,by this method it is intended to soak the land uniformly by allowing the water to flow through furrows drawn #c to #h feet apart1 with a gentle slope from the supply or head ditch2 the flow being continued until the water has reached the far end of the furrows1 or longer according to the nature of the soil1 especially if another ditch to receive the surplus flow lies below4 ,the furrows should subsequently be closed by means of the plow or cultivator2 but even if left open they are much less a source of waste by evaporation than would be a flooded surface4 ,the water thus1 in the main1 soaks downward and only reaches the surface by capillary rise1 so that the land between the furrows is not sensibly compacted when the furrows have been made deep enough4 ,evidently this is a much more rational procedure than surface flooding1 as it tends to leave most of the surface in loose tilth1 while penetrating to much greater advantage1 because of the ready escape of the air from the soil4 ,it is the system naturally and almost exclusively used in truck gardens and orchards1 and generally where crops are grown in drills or rows sufficiently far apart to permit of cultivation4 ,illustration3 ,furrows #f inches deep in ,heavy ,loam ,soil ,illustration3 ,narrow and ,wide ,furrows in ,sandy ,loam ,soil ,illustration3 ,furrows #e and #aj inches deep in ,sandy ,loam ,soil ,water running1 in each1 seven hours ,,fig4 #dc4--,profiles of ,water penetration in ,furrow ,irrigation4 ,the figure annexed#ij shows the manner in which water sinks and spreads from furrows of various depths and widths1 as actually observed in the work of the ,irrigation ,division of the ,u4 ,s4 ,dep't of ,agriculture1 under the direct supervision of ,prof4 ,r4 ,h4 ,loughridge of the ,california ,station4 ,the mode of percolation is shown for two soils1 a heavy loam and a sandy one1 both in the vicinity of ,riverside1 ,cal4 #ij ,published by permission of the ,department4 ,the upper section shows the variation in penetration in one and the same soil with the same kind of furrow1 the broken line indicating the cessation of the flow in the furrows2 after which there was a still farther penetration of the water to from #f to #i inches deeper4 ,the second section from above shows the percolation of the water respectively in wide and narrow furrows of the same depth4 ,it is evident at a glance how much more effective is the wide furrow in utilizing the limited time during which the irrigator usually has the flow at his command4 ,the third section shows several practically important points in favor of the wide and deep instead of narrow and shallow furrow4 ,it is seen that in doubling the width and depth1 the penetration has also nearly doubled4 ,moreover1 it is seen that in the deep furrow the water has not in the course of seven hours reached the surface at all1 being still six inches away2 so that in view of the diminishing ratio of capillary ascent1 it probably would not have reached the edge of the furrow1 at the surface1 in less than thirty hours4 ,thus all surface evaporation1 which oftentimes causes the loss of #ej of the water entering the shallow furrows1 would be prevented2 and a dry furrow-slice might be turned into the furrow immediately after the cessation of the water-flow1 effectually obviating the need of subsequent tillage also4 ,the cost of the latter1 together with the saving in water1 and increased efficiency of the water by deeper penetration1 will much more than offset the additional cost and trouble of plowing deeper furrows4 ,there is therefore every reason for doing away with the wasteful1 easy-going practice of irrigating in numerous shallow furrows1 by which the irrigator loses up to half of the water paid for1 by evaporation2 is compelled to wait for the soaked surface to dry before being able to turn back a furrow-slice into the furrows to prevent the drying-out of their moisture2 and by losing penetration of the water1 is obliged to irrigate again within a much shorter time than will be necessary if deep-furrow irrigation be used4 ,a similar experiment with deep and shallow furrows was made at the ,southern ,california station near ,pomona in #aija1 as reported in ,bulletin #ach of the ,california ,station4 ,the results as far as they went were precisely similar1 and upon the basis of these the writer earnestly advocated deep-furrow irrigation1 and had the satisfaction of seeing it strongly approved by orange-growers at ,riverside and elsewhere1 by putting it into practice4 ,in addition to the saving and better utilization of the water used1 this mode of application has the advantage of preventing the roots from coming too near the surface2 it will also largely eliminate 8irrigation hardpan0 or plowsole4 ,the results produced by long-continued shallow plowing and irrigation in shallow furrows is well illustrated in the last of the irrigation profiles1 which shows the observations made on the same land as the others1 but where rational cultivation and deep-furrow irrigation had not yet been introduced4 ,it will be seen that after applying1 and of course paying for1 the water for three days1 its average penetration was only about eighteen inches2 so that the trees of the orchard received very little benefit1 and were supposed to be needing fertilization when in fact they were simply suffering from lack of water at the lower roots4 ,one somewhat unexpected point is shown by these diagrams1 viz41 the slight sidewise penetration of the water2 the wetted areas having a nearly vertical lateral outline4 ,this means1 of course1 that unless the furrows run very near the trees of an orchard1 the soil immediately beneath the trees will remain dry2 thus inducing the roots to spread sideways and losing depth of penetration and soil4 ,it will be noted especially in the lower figure that here again the deep furrow offers a material advantage over the shallow1 the sidewise spread being much more pronounced than in the shallow furrow alongside4 ,distance ,between ,furrows and ,ditches4--,the distance between the furrows must1 of course1 be proportioned to the readiness with which the water penetrates1 being less as the land is of closer texture4 ,the distance between head ditches must1 on the contrary1 vary in the opposite sense1 since if these are too far apart1 the water near the head ditch will in sandy lands be wasting into the subdrainage before the end of the furrows is reached2 so that the distribution will be very uneven4 ,the great differences observed between crops1 and especially trees1 below and above the head ditches1 are mainly due to this unevenness in water distribution1 caused by too great distance between successive head ditches4 ,each farmer must himself1 however1 determine by actual trial the proper distances between ditches as well as furrows1 for his particular case2 since everything depends upon the rapidity with which water will penetrate the soil and subsoil4 ,actual tests to determine this point#ia should be the first step1 before laying off the system of ditches as well as furrows4 ,it not uncommonly happens that the failure to do this at first1 compels a subsequent total change of arrangements in this respect4 7,see page #bec below74 #ia ,such tests can be readily made by any one1 by digging a pit to four or five feet depth1 and supplying water to a shallow basin dug into the surface #h to #ab inches distant from the vertical wall of the pit4 ,the descent of the water is then readily observed on the vertical side of the pit nearest to the water basin4 ,preliminary tests with soil probe 7see chap4 #aj1 p4 #agg74 ,thus while in some very pervious land furrows may be six or even eight feet apart1 in other cases1 in certain finely pulverulent or silty soils such as the 8dust soils0 described in a former chapter2 7see chapter #f1 p4 #ajd71 furrows drawn three feet apart may fail to allow the water to penetrate so as to prevent grain on the middle foot from suffering from drought after the water has run for twenty-four hours4 ,irrigation by lateral ,seepage4--,is in reality a mere modification of furrow irrigation1 practiced in the case of lands very readily permeable1 and where water is abundant4 ,the fields are laid off in 8lands0 twelve to twenty-five feet wide1 with a deep furrow or narrow ditch between1 from which water percolates in a short time so as to overlap from the two sides4 ,in this case sometimes the water does not reach the surface visibly at all2 a very great advantage where alkali exists1 as surface evaporation1 and the consequent accumulation of alkali1 is thus effectually prevented2 while deep-rooting is favored to the utmost4 ,basin ,irrigation4--,in this method of irrigation1 practiced only in the case of trees and sometimes vines1 and when water is scarce1 a wide circular furrow or basin is excavated around each trunk and water is run either from one to the other1 or sideways from a furrow laid along the rows4 ,the water thus applied of course percolates immediately around the trunk first1 and in practice is found to follow also the large roots2 so that it goes precisely where it is most wanted1 besides forming a vertical body of moist soil reaching to considerable depth1 where it is most desirable that the root system should follow4 ,by this deep penetration to natural moisture in the depths of the soil1 comparatively small quantities of water produce very marked effects4 ,on the same principle1 the grape vines which bear some of the choicest raisins of ,malaga on the arid coastward slopes1 are made to supply themselves with moisture1 without irrigation1 by opening around them large1 funnel-shaped pits1 which remain open in winter so as to catch the rain1 causing it to penetrate downward along the taproot of the vine1 in clay shale quite similar to that of the ,california ,coast ,ranges1 and like the latter almost vertically on edge4 ,yet on these same slopes scarcely any natural vegetation now finds a foothold4 ,similarly the 8ryats0 of parts of ,india water their crops by applying to each plant immediately around the stem such scanty measure of the precious fluid as they have taken from wells1 often of considerable depth1 which form their only source of water-supply4 ,perhaps in imitation of these1 an industrious farmer has practiced a similar system on the high benches of ,kern ,river1 ,california1 and has successfully grown excellent fruit for years1 on land that would originally grow nothing but cactus4 ,sub-irrigation from pipes has been applied in a similar manner4 ,a combination of the furrow- and basin-irrigation system is sometimes practiced in southern ,california by drawing the furrow so as to bring the tree within a square1 one side of which is left closed4 ,the same result may be accomplished by plowing cross furrows at right angles near the tree and then placing check-boards so as to force the water along the rows1 zigzagging1 on three sides4 ,the basin irrigation of orchards was originally largely practiced in ,california1 but has now been mostly abandoned for furrow irrigation4 ,the latter has been adopted partly because it requires a great deal less hand-labor1 partly under the impression that the whole of the soil of the orchard is thus most thoroughly utilized2 partly also because of the injurious effect upon trees produced at times by basin irrigation4 ,the explanation of such injurious effects is1 essentially1 that cold irrigation water depresses too much the temperature of the earth immediately around the roots1 and thus hinders active vegetation to an injurious extent1 sometimes so as to bring about the dropping of the fruit4 ,this of course is a very serious objection1 to obviate which it might be necessary to reservoir the water so as to allow it to warm before being applied to the trees4#ib ,in furrow-irrigation the amount of soil soaked with the water is so great that the latter is soon effectually warmed up1 besides not coming in contact too intimately with the main roots of the tree2 along which the water soaks very readily when applied to the trunk1 thus affecting their temperature much more directly4 ,it is for the farmer to determine which consideration should prevail in a given case4 ,if the water-supply be scant and warm1 the most effectual use that can be made of it is to apply it immediately around the tree1 in a circular trench dug for the purpose4 ,when on the contrary1 irrigation water is abundant and its temperature low1 it may be preferable to practice furrow irrigation1 or possibly even flooding4 #ib ,see below1 chap4 #ag4 ,as to the supposed more complete use of the soil under the latter two methods1 it must be remembered that while this is the case in a horizontal direction1 if irrigation is practiced too copiously under the shallow-furrow system1 it may easily happen that the gain made horizontally is more than offset by a corresponding loss in the vertical penetration of the root-system4 ,this is amply apparent in some of the irrigated orange groves of southern ,california1 where the fine roots of the trees fill the surface soil as do the roots of maize in a corn field of the ,mississippi ,states2 so that the plow can hardly be run without turning them up and under4 ,in these same orchards it will often be observed1 in digging down1 that at a depth of a few feet the soil is too water-soaked to permit of the proper exercise of the root-functions1 and that the roots existing there are either inactive or diseased4 ,that in such cases frequent irrigation and abundant fertilization alone can maintain an orchard in bearing condition1 is a matter of course2 and there can be no question that a great deal of the constant cry for the fertilization of orchards in the irrigated sections is due quite as much to the shallowness of rooting induced by over-irrigation1 as to any really necessary exhaustion of the land4 ,when the roots are induced to come to and remain at the surface1 within a surface layer of eighteen to twenty inches1 it naturally becomes necessary to feed these roots abundantly1 both with moisture and with plant-food4 ,this has1 as naturally1 led to an overestimate of the requirements of the trees in both respects4 ,had deep-rooting been encouraged at first in the deep soils of the southern 8citrus belt10 instead of over-stimulating the growth by surface fertilization and frequent irrigation1 some delay in bearing would have been compensated for by less of current outlay for fertilizers1 and less liability to injury from frequently unavoidable delay1 or from inadequacy1 of irrigation4 ,irrigation by ,underground ,pipes4--,where economy in the use of irrigation water is a pressing requirement1 its distribution through underground pipes affords the surest mode of accomplishing that end1 in connection with the application of the water in accordance with the principles just discussed4 ,the enormous saving of water effected by its conveyance in cement-lined ditches or concrete pipes1 as compared with earth ditches1 if additionally combined with its application to individual trees or vines1 presents the maximum of economy that can be effected4 ,the actual use of this method is unfortunately limited in practice by the high first cost of piping2 but as its use renders unnecessary the digging of basins and plowing of furrows and their subsequent closing-up1 it is when once established by far the cheapest system1 both as to the use of water and of labor4 ,the best results of this system are undoubtedly achieved by the use of iron pipes for the distribution in field and orchard1 whatever may be the material used for the main conduits4 ,the use of concrete and tile in small sizes proves in the end very expensive1 because of frequent breakage1 and leakage due to varying pressure in the supply pipes or reservoirs2 as well as from even slight earthquake tremors1 undermining by water or by the burrowing of animals1 and many other accidents which do not affect an iron pipe system4 ,the pipes must in any case1 of course1 be laid deep enough to be out of reach of the deepest tillage2 therefore not less than one foot1 and preferably eighteen inches4 ,a proper construction of the outlets1 permitting of exact regulation of the flow and ready operation from above ground1 as well as preventing their being clogged by earth1 rust1 roots or burrowing animals1 insects etc41 is of course of the greatest importance4 ,a variety of devices for this purpose is already on the market4 ,,quality ,,of ,,the ,,irrigation ,,water4 ,saline ,waters4--,considering the large amount of water annually used in irrigation1 among the most needful precautions to be observed by the irrigator is in the testing of the quality of his water-supply4 ,first among the points to be noted is the possible content of soluble 8alkali0 salts4 ,while in most cases what is called the 8rise of the alkali0 is due to the salts already contained in the soil and subsoil1 in but too many the evil is either brought about1 or greatly aggravated1 by the excessive saline contents of the water used in irrigation4 ,the effects of the use of saline irrigation water 7containing in this case about #ajj grains per gallon1 or #agjj parts per million7 are shown in the accompanying plate4 ,the predominant ingredients of these alkali salts were common salt and carbonate of soda4 ,in the lands near ,corona1 ,cal41 where this case was observed1 the original alkali-content of the soil was about #bejj pounds per acre in four feet depth1 and had been just quadrupled1 with the results shown2 viz41 complete defoliation of the orange trees1 while on the same land1 where the trees had been irrigated with good artesian water1 the orchard was in fine condition4 ,limits of ,salinity4--,it is not easy to assign a definite limit of mineral content beyond which water should be considered unfit for irrigation purposes2 partly because of the differences in the kind of the mineral salts1 partly because the nature of the soil and the amount of water at command1 materially influence its availability4 ,illustration3 ,,fig4 #dd4--,orange ,trees ,irrigated with ,artesian ,water4 ,illustration3 ,,fig4 #de4--,lake ,elsinore ,water1 ,three ,years4 ,forty grains per gallon is usually assigned as the limit for potable as well as irrigation waters4 ,but if most or the whole of such mineral contents should consist of the carbonates and sulfates of lime and magnesia1 the water while unsuitable for domestic use may be perfectly available for irrigation1 since these salts are either beneficial or harmless in the amounts likely to be introduced by the water4 ,but if most or the whole of such forty grains should consist of 8alkali salts0 proper1 viz41 the sulfates1 chlorids and carbonates of potash and soda1 or if they should contain even small amounts of the chlorid of magnesium1 they might render the water either wholly unsuitable for irrigation1 or if used it would be needful to take the mineral content into consideration1 by regulating its application accordingly4 ,it has been found in ,california that practically the upper limit of mineral content for irrigation water under the ordinary practice lies below seventy grains per gallon in all cases2 for when this strength is reached1 even though such water may bathe the roots of almost any plant with impunity1 yet accidental concentration by evaporation is so certain to happen1 that injury to crops is practically almost unavoidable4 ,in ,south ,dakota and other parts of the ,american semi-arid region1 waters containing seventy grains and even more of alkali salts per gallon are annually used during the short irrigation season4 ,this can be done harmlessly because the aggregate amount used is only small1 and the more abundant rainfall of that region annually washes the salts out of the soil4 ,but where almost the full amount of water required by crops must be supplied by irrigation1 the total amount of salts thus introduced would speedily render the land uncultivable4 ,according to the observations of ,means and other explorers#ic of the ,u4 ,s4 ,dep't of ,agriculture1 waters of much higher mineral content are used for irrigation both in ,egypt and in the ,saharan region1 some going as high as #hjjj parts per million1 or #bad grains per gallon4 ,the cultivators are said to be very skilful in the use of these waters1 applying them only to plants of known resistance1 and in certain ways4 ,these ways include doubtless a good deal more time and patience than ,american irrigators are ordinarily willing to bestow upon their work4 ,much depends of course not only upon the character of the salts in the water1 but also upon the long experience had in the old irrigation regions4 #ic ,bull4 ,no4 #ba1 ,bureau of ,soils2 also circular ,no4 #aj1 ibid4 ,mode of using ,saline ,irrigation ,waters4--,the fact that abundant growths of native as well as cultivated plants may sometimes be seen on the margins of 8alkali lakes0 where water of over a hundred grains of mineral salts per gallon continuously bathes the roots1 while the same plants perish at some distance from the water's edge1 points the way to the utilization1 in emergencies1 of fairly strong saline waters2 viz41 by the prevention of their concentration to the point of injury by evaporation4 ,it is clear that when such waters are used sparingly1 so as to penetrate but a few feet underground1 whence the moisture re-ascends for evaporation at the surface1 a few repetitions of its use will accumulate so much alkali near the surface as to bring about serious injury4 ,if1 on the other hand1 the water is used so abundantly that the roots may be considered as being1 like the marginal vegetation of alkali lakes1 bathed only by water of moderate strength1 no such injury need occur2 and what does accumulate in consequence of the inevitable measure of evaporation occurring in the course of a season1 may be washed out of the land by copious winter irrigation4 ,this1 of course1 presupposes that the land1 as is mostly the case in the arid region1 is readily drained downwards when a sufficiency of water is used4 ,when this is not the case1 e4 g41 in clay or adobe soils1 or in those underlaid by hardpan1 waters which in sandy lands could have been used with impunity1 may become inapplicable to irrigation use4 ,apparent ,paradox4--,the prescription to use saline waters more abundantly than purer ones1 in order to avoid injury from alkali1 though paradoxical at first sight1 is therefore plainly justified by common sense as well as by experience1 in pervious 7sandy7 soils2 while in difficultly permeable ones1 their use may be either wholly impracticable1 or subject to very close limitation4 ,sometimes the alternate use of pure and salt-charged water serves to eke out a too scant supply of the former4 ,but in all such cases1 close attention to the measure of water that will wet the soil to a certain depth1 and 8eternal vigilance0 with respect to the accumulation of alkali near the surface1 must be the price of immunity from injury4 ,in all cases the farmer should know how much of alkali salts he introduces into his land with the irrigation water1 and watch that it does not approach too closely1 or exceed1 the tolerance of his crops for alkali salts1 as given in chapter #bf4 ,use of ,drainage ,waters for ,irrigation4--,when lands charged with alkali salts are being reclaimed by drainage1 the question sometimes arises whether the drainage-water may not be used for irrigation1 lower down4 ,this of course depends entirely upon the amount of alkali in the water1 the nature of the lands to be irrigated1 and the manner of applying it4 ,in the ,fresno drainage-district of ,california it has been shown that some of the drainage-water contains not more than #be to #cj grains per gallon of objectionable salts1 and such waters could of course be used on pervious lands with the precautions above noted4 8,black ,alkali0 ,waters4--,as regards1 however1 waters containing any large proportion of carbonate of soda1 it must be remembered that even very dilute solutions of salsoda serve to puddle the soil and thus render it difficultly tillable4 ,when such waters are used it is necessary to forestall injury either by the use of gypsum in the reservoir or ditch1 or by annually using on the land a sufficient amount of gypsum to transform the carbonate of soda into the relatively innocuous sulfate4 ,variations in the ,saline ,contents of ,irrigation ,waters4--,when irrigation waters are derived from deep wells1 there is little if any variation of their saline contents to be expected1 and a single analysis will serve permanently4 ,but in the case of relatively shallow wells1 from which the water must be raised by pumping1 it not unfrequently happens that after a series of seasons of short rainfall1 saline waters are brought up by the pump and may seriously injure crops and orchards4 ,again1 in the case of streams and rivers whose flow becomes very small in summer1 the saline content may increase to several times the amount carried at the time of high water4 ,both kinds of cases occur in southern ,california1 in ,arizona1#id ,new ,mexico and other states of the arid region4 ,the ,gila1 ,pecos and upper ,rio ,grande are cases in point1 and to a certain extent the ,colorado of the ,west4 #id ,bull4 ,ariz4 ,exp't ,sta4 ,no4 #dd4 ,muddy ,waters4--,in the latter as well as other streams of ,arizona1 there is another point which sometimes creates difficulties to the irrigator1 together with some current expense4 ,it is the amount of silt or mud carried by the water1 which while it is a benefit to the land over which it is spread1 78warping07 as in the classic case of the ,nile1 often clogs the irrigation ditches to such an extent as to cause considerable inconvenience and expense in cleaning them out4 ,this is especially the case in the streams draining pasture lands that have been overstocked1 and where the destruction of the natural herbage allows the rain water to run off rapidly1 at first forming runlets and then gullies and ravines that originally were simply cow-paths leading toward the watering places4#ie ,the devastation of lands thus caused in ,arizona is almost as great as that which has occurred in the ,cotton states1 as mentioned above chap4 #ab4 p4 #bag4 #ie ,bull4 ,arizona ,exp't ,station ,nos4 #b1 #ch4 ,these variations in the character of the irrigation water must of course be watched by the farmer who does not receive directly from mountain streams1 or from deep artesian wells water known to have a constant content of saline matter4 ,,the ,,duty ,,of ,,irrigation ,,water4--,the amount of water thought to be needed for the production of satisfactory crops varies widely in different regions1 ranging all the way from about two feet to as much as eight annually1 within the ,united ,states2 while in the sugar-cane fields of the ,hawaiian ,islands as much as three inches per week1 or over twelve acre-feet in the course of the year1 have been thought to be beneficial1 if not absolutely required for the best crop results4 ,as has been stated above 7chap4 #ab1 p4 #bae71 the rainfall limit below which irrigation becomes1 if not absolutely essential1 at least a highly desirable condition for the safety of crops1 is usually assumed to lie at about #bj inches 7#ejj milimeters74 ,this general statement is1 however1 subject to material modification according to the manner in which the rainfall is distributed4 ,thus in central ,montana with #bd inches of rainfall distributed throughout the year1 irrigation is indispensable2 while in the ,santa ,clara valley of central ,california1 with an average rainfall of #ae inches falling through the winter and spring1 the growth of all ordinary field crops has for fifty years not failed oftener than is commonly the case in the humid region of the ,north ,central states4 ,this is because in ,california the winter and spring are the growing seasons1 while the rainless summers do not stand in the way1 for crops are already harvested2 and the deep rooting of trees and vines provides these with the needful moisture from the depths of the substrata 7see chap4 #aj1 pp4 #afc to #agc74 ,it would thus seem that twenty inches of irrigation water properly applied ought to be sufficient for all purposes1 when added to the natural rainfall1 which is rarely entirely absent4 ,yet in actual practice less than #bd acre-inches is rarely used1 and much more is the rule2 #gb to #if ins4 being sometimes used in ,arizona4 ,evidently enormous losses occur in practice1 and it is of the utmost importance to discover the causes of these4 ,causes of ,loss4--,since irrigation water is commonly measured at the distributing weirs1 loss from seepage and evaporation on the way to the fields is an obvious source of an overestimate of the water actually supplied to the farmer4 ,in sandy districts the loss thus incurred is reliably estimated at nearly #ej in many cases4 ,the apparent duty of the water is thus at once reduced to half its effect1 and four instead of two feet of water are supposed to have been used1 and are charged for4 ,evaporation resulting from surface flooding or use in shallow furrows may1 again1 cause the loss of from #cj to #ej of the water that actually reaches the land2 so that in the latter case1 between seepage and evaporation the irrigator may lose the effect of three-fourths of the water he pays for4 ,loss by ,percolation4--,finally1 the water may be wasted on the land itself in leachy soils by over-use1 i4 e41 it may percolate to a large extent beyond the reach of the roots when the flow is continued too long2 as will always be the case when the head 7supply7 ditches are laid too far apart1 so that the water may be wasting into the country drainage just below the upper ditch long before the water in the furrow reaches the lower one2 as illustrated in the upper one of the subjoined diagrams4 ,that this will not happen when the head ditches are nearer together1 is shown in the lower diagram4 ,illustration3 ,,figs4 #df1 #dg4--;,diagram showing loss by percolation when head ditches are too far apart4 ,the means of avoiding the mechanical losses have already been discussed1 and may be summarized thus3 tightening of leaky ditches2 use of water in deep furrows2 and ascertaining the rapidity of percolation 7see p4 #bdb7 so as to obtain a proper gauge for the time during which water should run1 and for the distances at which head ditches or furrows should be placed4 ,the importance of thus diminishing the losses of water is obvious when it is considered that if the duty of water can be reduced to twenty instead of forty or fifty acre-inches1 twice the area can be irrigated with the same amount of water1 or the cost of water correspondingly reduced4 ,it should be noted that when the land is leachy it may be pure waste to continue the flow beyond a few hours2 but the irrigation must then be more frequently repeated4 ,,evaporation4 ,alongside of and supplementary to the best possible utilization of the rainfall and irrigation water1 the prevention of unnecessary evaporation has to be considered4 ,evaporation from the soil's surface implies not only unnecessary loss of water that should have remained for the use of the crop1 but also the depression of temperature which1 as a rule1 is unfavorable to the best development of vegetation4 ,it is only in case of extreme stress from hot1 drying wind that such evaporation and the consequent depression of the temperature of the surface soil can be of advantage to the farmer4 ,the amount of water evaporating either from a water-surface1 or from a wet or moist soil1 varies greatly according to the climatic conditions1 and the state of the weather2 also according to the condition of the soil-surface4 ,there are damp climates1 and days or periods when1 the air being nearly saturated with moisture1 evaporation even from a water-surface will be almost insensible4 ,on the other hand1 with dry air and a high temperature1 enormous quantities of water may be evaporated in the course of a day4 ,the evaporation from water-surfaces interests deeply those who supply1 as well as those who are supplied with1 water from storage reservoirs2 evaporation from the soil-surface interests deeply all farmers1 and more especially irrigators whose water-supply is scanty1 or is paid for by them by measurement4 ,light rains1 as well as light surface irrigations1 may at times evaporate almost wholly without any effect save a lowering of the temperature of the soil4 ,in the case of snow1 it is a well-known fact in the northern arid regions that a light snowfall may in winter evaporate entirely without imparting any liquid moisture to the soil4 ,a loss of #ej of the water actually brought upon land by surface irrigation is of common occurrence in some portions of the irrigated region4 ,the dependence of evaporation upon air-temperature under conditions otherwise identical1 is well illustrated by the experiments made in #aijd by ,s4 ,fortier#if on the ,experiment ,station grounds at ,berkeley1 ,california1 at a time when under the influence of the sea breeze the average saturation of the air might be assumed at about #gj4 ,the tests were conducted in six tanks sunk into the ground so as to place the water-surfaces on a level with it1 and the water-temperatures were maintained in four of the tanks by means of ice or heating lamps4 ,the results are shown in the following table3 ,,summary ,,of ,,average ,,weekly ,,losses ,,by ,,evaporation1 ,,with ,,varying ,,temperatures ,,of ,,water1 ,,at ,,berkeley1 ,,cal41 ,,in ,,july ,,and ,,august1 #aijd4 ,temperature of water4 ,weekly evaporation4 ----------------------------------- ,degrees ,fahrenheit3 ,inches4 #ee4e #j4db #fb4j #j4gg #fi4b #a4ed #hj4a #c4jh #hi4b #c4ib ----------------------------------- #if ,progress ,report on ,coperative ,irrigations in ,calif42 ,cir4 ,no4 #ef1 ,office ,exp't ,stations4 ,a farther illustration is given in the subjoined table1 showing maxima and minima of monthly evaporation1 as well the totals of one 7seasonal7 year1 in three ,california localities where the air-saturation is considerably below that at ,berkeley1 ranging in summer from #ej to #bj and even less 7at ,calexico in the ,colorado desert73 ,,summary ,,of ,,evaporation-,,losses ,,from ,,water-,,surfaces1 ,,at ,,pomona1 ,,tulare1 ,,and ,,calexico1 ,,cal41 ,,from ,,july #a1 #aijc1 ,,to ,,july #ca1 #aijd4 ,pomona4 ,tulare4 ,calexico4 ---------------------------------------- -------- ,month4 ,inches4 ,month4 ,inches4 ,month4 ,inches4 ---------------------------------------- -------------------- ,maximum ,aug4 #aijc #i4jg ,july #aijc #ab4cd ,july #aijc #ad4dh ,minimum ,feb4 #aijd #b4eg ,jan4 #aijd #a4df ,jan4 #aijd #d4ci ----- ----- ------ ,totals for #ff4ib #gd4fh #ajh4bc year ---------------------------------------- -------------------- ,of these three stations1 ,pomona is located within reach of the ocean winds1 but distant #be to #cj miles from the shore4 ,tulare is situated in the upper ,san ,joaquin valley1 far in the interior2 ,calexico is in the southern part of the ,colorado desert1 with extremes of temperature ranging from #ac ,fahr4 in winter to #abj in summer4 ,evaporation in ,different ,climates4--,the following table conveys some general data regarding average evaporation from water-surfaces in different climates4 ,evaporation from the soil-surface depends largely1 of course1 upon the mechanical condition of the surface1 the extent to which it is wetted1 and the rapidity with which moisture will be supplied from the subsoil as the surface dries4 ,a field plowed into rough furrows will evaporate more water than when harrowed1 because of the larger surface exposed2 and a harrowed field moderately compacted by rolling will lose less water by evaporation than when unrolled1 other things being equal4 ,on the other hand1 a thoroughly compacted surface1 even if suffering less loss at first than a plowed or harrowed field1 will continue to lose moisture longer by withdrawing it from the substrata by its superior capillary suction2 while a loose surface1 once dried out1 will prevent farther loss from the subsoil very effectually1 as stated below4 ,,table ,,showing ,,evaporation1 ,,from ,,water-,,surface ,,exposed ,,in ,,shallow ,,tanks1 ,,near ,,water ,,or ,,ground ,,surface4 ,years4 ,inches4 ---------------------------------------- ----------------------- ,rothamsted1 ,england #i #ag4hj 7#af4f to #ah4d7 ,london1 8 #ad #bj4ff ,oxford1 8 #e #ca4jd ,munich1 ,germany 8 #bd4jj ,emdrup1 ,denmark #aj #bg4ji ,cambridge1 ,massachusetts #a #ef4jj ,syracuse1 ,new ,york #a #ej4bj ,logan1 ,utah #a #eb4ci ,tucson1 ,arizona #a #ge4hj ,fort ,collins1 ,colorado #aa #da4jj ,fort ,bliss1 ,texas #a #hb4gj ,san ,francisco1 ,california #de to #ej ,sweetwater ,reservoir1 ,san ,diego1 ,california #a #eg4f ,peking1 ,china 8 #ch4hj ,demerara1 ,south ,america #c #ce4ab ,bombay1 ,east ,india #e #hb4bh ,petro-,alexandrowsk1 ,west ,turkestan 8 #if4dj ,kimberley1 ,south ,africa 8 #ih4hj ,alice ,springs1 ,south ,australia 8 #ajc4ej ---------------------------------------- ----------------------- ,this table1 the data for which are taken from various sources1 exhibits clearly the enormous variations in evaporation in different countries1 and even in localities not very remote from each other4 ,the low evaporation near ,london is doubtless due to its foggy and hazy atmosphere1 but it is not clear why ,rothamsted should show so low an evaporation compared with ,oxford4 ,tropical ,demerara stands nearest to ,oxford in its evaporation2 ,bombay indicates its location on the hot and arid west coast of ,india1 despite its nearness to the sea4 ,the inland localities in the desert regions of ,south ,africa1 ,australia and ,western ,turkestan1 show how enormous may be the losses from evaporation of irrigation water1 unless the latter is applied with special care for their prevention4 ,thus1 with the wasteful methods of irrigation prevailing in portions of the ,american arid region1 it is certain that in many cases #ej and more of the water evaporates before it reaches the crops4 ,evaporation from ,reservoirs and ,ditches4--,the evaporation from water-surfaces especially may1 in many cases1 exceed the rainfall of the year1 so as to materially diminish the available water-supply in reservoirs4 ,thus the annual evaporation from the reservoir-lakes forming part of the water-supply of the city of ,san ,francisco1 ranges from #dj to #ej inches1 while the rainfall averages less than #bd inches4 ,were it not1 then1 for the prevention of evaporation by a covering of dry earth during summer1 no moisture would remain in the ground to sustain vegetation4 ,in the cool coast climate of ,berkeley1 ,cal41 directly opposite the ,golden ,gate and subject to its summer fogs1 evaporation from a water-surface maintaining the average climatic temperature of #fj1 was found to be inch during the month from the middle of ,july to the middle of ,august1 #aijd4 ,but at the high temperatures and low degree of air-saturation prevailing in the great interior valley1 or in the ,colorado desert1 the evaporation from water-surfaces is enormously increased1 exceeding even the figure given in the table for ,bombay4 ,hence the great importance of preventing all avoidable evaporation1 particularly in the use of irrigation water4 ,prevention of ,evaporation2 ,protective ,surface ,layer4--,the loose tilth of the surface which is so conducive to the rapid absorption of surface-water1 is also1 broadly speaking1 the best means of reducing evaporation to the lowest possible point4 ,for while it is true that the floccules of well-tilled soil permit of the ready access of air1 and therefore of evaporation1 it is also true that these relatively coarse compound particles are incapable of withdrawing capillary moisture from the denser soil or subsoil underneath2 just as a dry sponge is incapable of absorbing any moisture from a wet brick1 while a dry brick will readily withdraw nearly all the water contained in the relatively large pores of the sponge 7see chap4 #aa74 ,a layer of loose1 dry surface-soil is therefore an excellent preventive of evaporation of the moisture from soils1 and may be regarded as the natural and most available means to be used by the farmer1 both for the prevention of evaporation and to moderate the access of excessive heat and dryness to the active roots4 ,as regards the desirable thickness of this protective layer of tilled surface-soil1 it should be kept in mind that in the humid region1 where rain can be expected at intervals of from one to three weeks1 the feeding roots may usually be found within a few inches of the surface2 while in the arid region1 where irrigation is practiced at long intervals or sometimes not at all1 so that no water enters the soil oftener than from two to six months1 the roots necessarily vegetate at lower depths1 and hence the protective surface-layer can1 and should be1 of greater thickness1 to prevent the penetration of excessive heat and dryness during the long interval4 ,the failure to appreciate this necessary difference often leads to heavy losses on the part of newcomers to the arid region1 who in this as in other respects are apt to follow blindly the precepts familiar to them in the ,east1 until taught better by sore experience4 ,in the ,east and ,middle ,west a depth of three inches is considered the proper one for the protective surface-layer2 and in the case of maize even this is considered excessive in many cases4 ,in the arid region this depth should be at least doubled where irrigation is not practiced at least every four to six weeks2 and in some sandy soils even seven and eight inches is not too much for effective protection4 ,illustrations of ,effects of ,surface ,tillage4--,the efficacy of loose surface tilth in preventing evaporation1 as compared with mere superficial scratching or with the total omission of cultivation1 is well exemplified in a series of investigations conducted on this subject during the extremely dry season of #ahih1 by the ,california ,experiment ,station2 the seasonal rainfall having during that year been on an average from one-third to one-half only of the usual amount1 so as to test to the utmost the endurance of all growing plants4 ,some of the details of this investigation have been given above 7p4 #bad7 in connection with the question of moisture requirements of crops4 ,loughridge#ig also investigated the moisture conditions in adjacent orchards differently treated in cultivation4 ,in one of these cases two orchards of apricots were separated only by a lane1 and the soil identical2 but one owner had omitted cultivation1 while the other had cultivated to an extra depth in view of the dry season apparently impending4 ,the results are best shown by the plates below1 showing representative trees and the annual growth made by each4 ,the table annexed shows the differences in the moisture-content of the two fields to the depth of six feet1 in ,july3 ,,moisture ,,in ,,cultivated ,,and ,,uncultivated ,,land4 ,cultivated4 ,uncultivated4 ,depth in soil4 ------------------------------------- ,per cent4 ,tons per,per cent4,tons per acre4 acre4 ---------------------------------------- ---------------- ,first foot #f4d #abh #d4c #hf ,second foot #e4h #aaf #d4d #hh ,third foot #f4d #abh #c4i #gh ,fourth foot #f4e #acj #e4a #ajj ,fifth foot #f4g #acd #c4d #fh ,sixth foot #f4j #abj #d4e #ij --- --- --- --- ,total for six foot #f4c #gef #d4b #eab ---------------------------------------- ---------------- #ig ,rep4 ,calif4 ,expt4 ,sta4 for #ahig-ih1 p4 #fe4 ,the difference of #bdd tons per acre of ground shown by the analyses is quite sufficient to account for the observed difference in the cultural result4 ,the cause of this difference was that in the uncultivated field there was a compacted surface-layer of several inches in thickness1 which forcibly abstracted the moisture from the substrata and evaporated it from its surface2 while the loose surface soil on the cultivated ground was unable to take any moisture from the denser subsoil4 ,illustration3 ,cultivated4 ,illustration3 ,uncultivated4 ,,figs4 #dh1 #di4--;,apricot ,trees1 ,creek ,bench ,land1 at ,niles1 ,cal4 ,illustration3 ,,fig4 #ej4--,new ,growth and ,fruit on ,trees1 ,cultivated and ,uncultivated4 ,creek ,bench ,land at ,niles1 ,cal4 ,the cultural results were that on the cultivated ground the trees made about three feet of annual growth1 and the fruit was of good1 normal size2 while the trees in the uncultivated ground made barely three inches of growth1 and the fruit was stunted and wholly unsaleable4 ,it may be added that when1 instructed by the season's experience1 the owner of the 8uncultivated0 orchard cultivated deeply the following season1 his trees showed as good growth and fruit as his neighbor's4 ,,evaporation ,,through ,,the ,,roots ,,and ,,leaves ,,of ,,plants4 ,undesirable as is the evaporation from the surface of the soil1 under all but exceptional conditions the evaporation from the leaves of plants is one of the essential functions of vegetable development4 ,not only because water serves as the vehicle of the plant-food absorbed by the roots and to be organized by and redistributed from the leaves1 and the aeration occurring in the latter must of necessity result in a certain degree of evaporation2 but largely because the conversion of liquid water into vapor serves to prevent an injurious rise of temperature in the leaves under the influence of hot sunshine and dry air4 ,it is undoubtedly for the latter purpose that the greater part of the enormous amount of water required1 as above stated 7chap4 #aa7 for the production of one part of dry substance1 is actually used4 ,when sufficient water to supply the required evaporation through the leaves cannot be brought up from the soil1 the plant begins to wilt2 or in the case of some plants with very thin and soft leaves the blade normally begins to droop during the hottest hours of the day2 thus escaping excessive exposure to the sun's rays1 and recovering their turgor later in the afternoon4 ,the amount of water actually evaporated from orchard trees has unfortunately not been directly determined1 the investigations made in this respect having borne mainly upon forest trees4 ,the ,austrian ,forest ,experiment ,station made a series of elaborate investigations on this subject in #ahgh1 and the following data 7quoted from the ,report of the ,u4 ,s4 ,dep't of ,agriculture for #ahhi7 convey some idea of the results4 ,it was found that the surface-areas of the leaves do not give reliable results1 but that these depend very largely upon the thickness 7mass7 of the leaves4 ,the dry weight of the latter was found1 as in the case of field crops1 to correspond most nearly to the observations made directly4 ,it was thus found that e4 g4 birch and linden transpired during their annual period of vegetation from #fjj to #gjj pounds of water per pound of dry leaves2 oaks #bjj to #cjj1 while the figures for ash1 beech and maple were in between4 ,on the other hand the conifers--spruce1 fir and pine--ranged1 under the same conditions1 from #cj to #gj pounds of water only4 ,in another year1 these figures were increased for deciduous trees to from #ejj to #ajjj1 the conifers1 #ge to #bjj pounds4 ,this great variability in different seasons1 together with other elements of uncertainty1 render these figures only roughly approximate2 but it will be noted that the figures for deciduous trees are in general of the same order as those given above for field crops4 ,assuming the evaporation for citrus trees to be approximately the same as for the ,european evergreen oak 7,q4 cerris7 viz4 #ejj pounds per pound of dry matter1 and taking the weighings made by ,loughridge of the leaves of a #ae-year-old orange tree at ,riverside as a basis 7#dj pounds of dry leaves71 the water evaporated by each such tree would be about #bj1jjj pounds per year1 or about #ajjj tons per acre of #ajj trees4 ,this is equivalent to about #i acre-inches of rainfall1 out of the #ce inches commonly given4 ,since different plants evaporate very different amounts of water during a given time1 according to their leaf-surface and the number and size of their stomates1 the maintenance of the equilibrium between the soil-supply and the evaporation of the leaf-surface requires correspondingly varying moisture-conditions in the soil4 ,therefore desert plants1 with their elaborate structural provisions against leaf-evaporation1 will develop normally1 and without wilting1 under conditions which in the case of most culture plants would result in severe injury or death4 ,since diminution of leaf-surface will in all cases diminish evaporation1 the heroic measure of cutting back the twigs and branches of shrubs and trees in seasons of severe drought is sometimes resorted to in order to save their life4 ,in ,nature this diminution of leaf-surface may be observed in many cases of desert plants1 whose 8fugacious0 leaves are developed during the rainy season1 in winter and early spring2 dropping off so soon as the dry season begins1 and leaving only the green surface of twigs1 stems or spines to perform the functions of the leaves4 ,the shading of the ground by leafy vegetation will1 of course1 greatly diminish and sometimes suppress evaporation from the soil-surface2 thus very nearly fulfilling the same conditions referred to above 7chap4 #g1 page #aaa7 in discussing the effect of natural vegetation in rendering tillage unnecessary2 the beating of rains1 and the formation of surface crusts1 being alike prevented4 ,this fact is of essential importance in contributing to the welfare of crops sown broadcast1 where subsequent cultivation is impracticable4 ,weeds ,waste ,moisture4--,the injurious effects of weedy growth among culture plants are in most cases due quite as much to the appropriation of moisture that should have gone to the crop1 as to the abstraction of plant-food1 to which the injury is generally attributed4 ,this is much more obvious in the arid region1 where during the dry summers every pound of moisture counts1 than where summer rains obscure this influence4 ,it has led orchardists in ,california almost to an excess of clean culture1 resulting in the burning-out of the humus from the bare surface-soil during the long1 hot summers1 and an injurious compacting impossible to remedy by the most careful tillage4 ,it thus happens that green-manuring1 the natural remedy for this evil1 cannot safely be done there with summer crops1 but must be accomplished with winter crops1 such as can be turned under before the dry season begins4 ,the same objection holds against the growing of summer crops between the orchard-rows4 ,,distribution ,,of ,,moisture ,,in ,,the ,,soil ,,as ,,affected ,,by ,,vegetation4 ,the investigations of ,wollny and others have long shown quantitatively what common experience has taught the farmer1 viz41 that a field in crops or grass is always drier within the soil-mass penetrated by the roots than is a cultivated field bare of crops1 unless perhaps when heavily crusted on the surface4 ,the depletion of moisture caused by grass sward is the most easily observed because of the shallowness of the root-system2 and this is one cause at least why grass sward does not occur naturally in the arid region1 and when planted cannot be maintained without irrigation repeated at short intervals4 ,deeper-rooted plants of course deplete the soil at different and varying levels2 and where surface roots are few or absent it may readily happen that the surface soil is moister than the subsoil4 ,this was very strikingly shown by the investigations of ,ototzky in the ,south-,russian steppes1 in comparing both the moisture contents and the depth of bottom water as between forest land and the open plains4 ,on the steppe near ,chipoff1 ,government of ,voronej1 he found the ground water at from #c to #e meters 7#aj-af feet7 depth2 under the forest in the same region and in identical underground formations1 the water level stood at #ae meters4 ,in the ,black ,forest near ,cherson1 the water is found at about #ae feet beneath the surface2 under the steppe and in cultivated ground it stood at #aj feet4 ,at the same time the forest soil was moister in the upper two feet than the soil of the steppe1 where surface evaporation 7partly through shallow plant-roots1 partly direct7 was greater than under the shadow of the forest2 under which1 moreover1 there were few shallow rooted plants to draw upon the moisture of the surface soil4 ,the great evaporation from forests is a matter demonstrated by actual measurement2 hence it is not surprising that certain shallow-rooted trees should serve for the reclamation of wet ground1 as has been demonstrated on the large scale1 e4 g41 in the use of the eucalyptus in the ,pontine ,marshes of ,italy1 and of the maritime pine in the ,landes of western ,france4 ,thus the sanitation of swampy districts through tree-planting has become one of the established measures in their settlement4 ,but this refers only to the evaporation from the trees themselves2 for in the shade of the forest1 a free water-surface is found to evaporate on the average only one-third as much as in open ground4 ,of course there must be a correspondingly great difference in the amounts of evaporation from the soil-surfaces in the respective areas4 ,the great draft made by the ,eucalyptus globulus upon soil-moisture has been also abundantly shown in ,california1 where on account of its rapid growth this tree has been largely used for windbreaks4 ,it was found that the trees deplete the fields of moisture for from twenty to thirty feet on either side1 so as to materially reduce crops within that limit4 ,for this reason the pine and cypress has of late found greater acceptance for this purpose4 ,mulching4--,covering the soil with straw or similar loose materials to prevent waste of moisture is a common garden practice everywhere1 although not usually applicable on the large scale4 ,it may readily however1 be carried to excess1 in preventing not only evaporation but also the warming of the soil which is so needful to the thrifty growth of plants4 ,it must not therefore be done too early in the season2 and after cold rains it sometimes becomes necessary to remove the mulch in order to allow the ground to become properly warmed4 ,mulching in early spring is often used to retard blooming of trees where spring frosts are feared4 ,in the arid region1 sanding of the surface is sometimes resorted to for the prevention of the evaporation which brings alkali salts to the surface4 ,but the necessity of repeating this dressing annually unless cultivation can be omitted1 restricts the use of this expedient to narrow limits4 ,the sanding of the surface of cranberry plantations in swamps or bogs in the northern parts of the humid region doubtless owes its efficacy largely1 if not chiefly1 to the retention of moisture1 while at the same time it prevents the consolidation of the surface1 so as to render tillage unnecessary4 ,,chapter ,,xiv4 ,,absorption ,,by ,,soils ,,of ,,solids ,,from ,,solutions4 ,,absorption ,,of ,,gases4 ,,air ,,of ,,the ,,soils4 ,,absorption ,,of ,,solids ,,from ,,their ,,solutions4 ,just as solids have the power of condensing gases upon their surfaces1 to an extent proportional to that surface1 and therefore to the state of fine division3 so fine powders have the power of withdrawing from solutions solids held in solution1 to an extent varying with the nature of the substance dissolved1 and the absorbing solid4 ,the most commonly-known manifestation of this principle is that sea-water filtering through the sands of the shore1 will at a certain distance become sensibly less brackish1 and finally so nearly fresh as to be capable of domestic use4#ih ,the extent to which this occurs is in a measure proportional to the fineness of the sand1 and to the amount of clay present in it4 ,this is a clearly physical effect1 independent of any chemical action whatever2 for it occurs equally with quartz sand1 charcoal1 glass1 limestone1 or other rock powders having no chemical effect upon the substance dissolved or upon the liquid dissolving it4 ,very large amounts of water are often required to remove all the soluble matter thus 8adsorbed40 #ih ,in many cases this decrease of salinity is probably due to a slow influx of fresh water from landward2 but very often it cannot be thus explained4 ,decolorizing ,action4--,one of the commonest applications of this principle is the decolorization of colored solutions by means of finely pulverized charcoal4 ,this property of charcoal1 as is well known1 is extensively utilized in the arts1 and particularly in the refining of sugar2 the charcoal used in this case being preferably bone charcoal 78bone black071 which on account of its state of extreme fineness1 and separation by the earthy particles with which it is associated1 is more effective than any other form4 ,it is rendered still more effective1 however1 by the extraction of these earthy particles 7calcic carbonate and phosphate7 by means of acid2 for by removal of the earthy particles1 the surface of the charcoal is greatly increased1 and its decolorizing as well as its absorbing power increases accordingly4 ,while in one and the same substance the decolorizing effect is more or less directly proportional to the fineness of the particles1 corresponding to increased surface1 it is nevertheless true that in this case1 as in that of the absorption of gases1 there are specific differences between different powders2 so that for example no other substance can replace charcoal in the decolorizing effect which it produces upon colored solutions4 ,it must not1 however1 be supposed that there is any special reason why coloring matters1 as such1 should be taken up by preference4 ,coloring matters are of all kinds of chemical composition1 and have in common only the fact that a relatively small amount produces a very strong coloring effect2 hence their name1 and hence also the apparently extraordinarily strong effect produced upon them by charcoal4 ,this effect is not1 however1 by any means greater than it is in the case of many other compounds which are colorless4 ,complex ,action of ,soils4--,the powdery ingredients of soils1 of course1 share this power with all other powders4 ,in the case of soils1 however1 the action is almost always much more complex than in that of charcoal1 because solutions that are passed through the soil are apt to act chemically upon one or the other of its ingredients1 usually resulting in a partial exchange of ingredients between the soil and the solution2 one or more of the constituents of the solution being retained by the soil1 while one or more of the 7basic7 soil constituents pass into the solution1 in combination with its acidic ingredients4 ,thus when a very dilute 7 or #a7 solution of potassic chlorid is filtered through almost any soil1 the first portions passing through will be practically free from potash1 but will contain the chlorids of calcium and magnesium4 ,but as more of the solution is passed through1 potash passes also ultimately without absorption4 ,in addition to the zeolitic and clay portions of the soil1 the humus is very effective in absorbing mineral ingredients from solution1 and retaining them in such manner as to be readily available to plant growth4 7,see chap4 #h1 p4 #abd47 ,in view of the almost invariable conjunction of physical and chemical effects1 it may be fairly said that no solution1 at least of mineral salts1 can pass through the soil without being changed in its concentration and chemical composition4 ,it is sometimes difficult to decide to which of the two classes of effects the several changes may be due4 ,purifying ,action of ,soils4--,the disinfecting action of dry soil1 absorbing offensive gases from manure piles and from earth closets1 has already been alluded to4 ,similarly it is a matter of common experience that the colored and otherwise offensive drainage from manure piles1 tanneries1 dyeworks1 etc41 is not only deodorized but also decolorized when passed through a sufficiently thick layer of clay soil4 ,the filtration through fine sand by which the drinking waters of cities are so commonly purified before delivery to the consumer are familiar examples of the same effects4 ,equally familiar1 however1 is the fact that this power of decolorization and retention of offensive compounds is limited2 that after a while the filtering earth or sand becomes saturated1 and afterwards the water or drainage will pass through without any sensible purification4 ,it is therefore clear that this purifying effect of earth cannot be relied upon for the permanent protection of wells from the surface-drainage from barnyard or house refuse4 ,even if fissures or layers of sand or gravel should not intervene so as to permit of the direct communication of surface-drainage with wells1 it is certain that in the course of a few years at most1 the intervening earth will become so far saturated with the noxious ingredients that the latter will pass through unhindered1 and may contaminate to a considerable extent the domestic supply of drinking water4 ,waste of ,fertilizers4--,the same1 of course1 holds true in regard to manure-water1 or soluble fertilizers of any kind used on the soil of a field4 ,the soil will retain them to a certain extent2 but beyond that limit any surplus added will be quickly washed through into the country drainage by the rains4 ,moreover1 a soil once so saturated will yield to rain water filtering through it1 notable amounts of all the ingredients absorbed in it2 and1 at least so far as the physically condensed soluble ingredients are concerned1 long-continued leaching with pure water will inevitably result in the withdrawal of additional amounts of absorbed ingredients1 apparently dividing themselves up pro rata between the water and the soil4 ,it is obviously of the utmost importance to the farmer to know to what extent the soil will retain manurial ingredients against the influence of leaching rains2 for unless this is taken into consideration1 it may readily happen that the fertilizer supplied before a rainy season will be washed through beyond the reach of plant-roots1 and so practically become a dead loss4 ,absorptive ,power ,varies4--,so far as the mere physical absorption is concerned1 it will readily be understood that a coarse sandy soil exercises less retentive influence upon dissolved substances than clay or humous soils4 ,in the humid region1 where sand is substantially nothing but granular silica 7see above1 chap4 #f1 page #hf71 the same may be measurably true as regards the chemical absorption also4 ,in the arid region1 on the contrary1 a great many sandy or silt soils1 very poor in clay1 exert fully as much chemical absorption as clay soils1 and are no more liable to the washing-out of soluble fertilizers introduced than are the latter4 ,for the chemical absorption lies chiefly in the zeolitic portion of the soil 7see above chap4 #c1 p4 #cg71 which in the humid region accumulates in the clay1 while in the arid it remains encrusting the sand and silt grains4 ,generalities regarding ,chemical ,absorption and ,exchange4--,in regard to the leaching-out and absorption or retention of substances important to agriculture1 the following general statement may be made3 ,the substances most likely to be leached out of soils are1 of bases3 soda1 magnesia and lime2 of acidic constituents3 chlorine1 sulfuric acid and nitric acid4 ,lime sometimes passes off with either of the above acidic ingredients1 and also in the form of carbonate4 ,substances rather tenaciously retained in soils are3 potash and ammonia among the bases1 and phosphoric acid among the acids4 ,thus 7as stated above7 when a weak 7one or two per cent7 solution of potassic chlorid or sulfate is poured upon a column of good soil several inches thick1 it will be found that the first portions passing through are free from potash1 but contain the chlorids or sulfates of magnesium and calcium4 ,if potassic nitrate be used1 lime and magnesia will pass off as nitrates2 while in the case of potassic phosphate1 both ingredients will be retained4 ,a solution of gypsum 7calcic sulfate7 will usually cause the passing-off of some of the magnesia1 soda and potash contained in the soil1 in the form of sulfates2 but the amount of potash thus dissolved soon diminishes to a mere trace4 ,solutions of potassic or amnionic phosphates will be absorbed and retained by the soil to a very considerable extent1 before the soil becomes saturated4 ,while it is true that the degree to which the soil retains the several ingredients may serve in a very general way to indicate their richness or poverty in the same1 the attempt to make such experiments serve to determine the agricultural needs of soils has met with but little practical acceptance4 ,drain ,waters4--,the table on p4 #bb1 chapter #b1 illustrates forcibly the working of the above principles1 which are verified by the composition of drain-waters4 ,in all1 the chief nutritive ingredients of plants1 except nitrogen1 are present in traces only2 chlorids1 nitrates and sulfates of sodium and magnesium form the bulk of the permanently soluble matter1 with usually a considerable proportion of calcic 7and magnesic7 carbonate1 depending upon the amount of the earth-carbonates present in the soil1 as well as upon that of oxidizable organic matter from which carbonic acid can be formed4 ,that calcic carbonate filters readily through the soil has already been somewhat elaborately discussed 7see chap4 #c1 p4 #da72 one of the results being that the surface soil is sometimes almost completely depleted of this important substance1 while it accumulates at a greater or less depth in the subsoil1 or in underdrains1 as the case may be4 ,of the ingredients appearing in the above list1 the one of greatest agricultural importance is nitric acid1 since chlorine and sulfuric acid1 as well as soda1 are required only in very small quantities by most culture plants2 so that they rarely need to be supplied in fertilizers4 ,nitric acid1 however1 is not only one of the most important fertilizers1 but also the most expensive2 hence the passing-off of nitrates in drainage-water is of such serious concern to the farmer1 that the causes of its occurrence1 and the means of preventing such loss1 should be fully understood4 ,this subject will1 however1 be more fully considered farther on4 ,the above ,distinctions not ,absolute4--,it should1 however1 be also understood that while the above statements hold good in a general way1 yet the line drawn is by no means an absolute one4 ,for just as in the case of physical adsorption the long passing-through of distilled water will gradually abstract the substances condensed on the surface of the soil-grains1 so an overwhelming amount of a solution of any one kind will have a tendency to substitute its own ingredients for those already present in the soil1 removing the latter to a greater or less extent1 even in the case of potash and phosphoric acid4 ,as an example in point1 may be cited the case of the natural minerals ,analcite and ,leucite1 which ,lemberg was able to reciprocally transform from their natural condition of soda- and potash-alumina silicates merely by alternate treatment with solutions of potassium and sodium chlorids respectively4 7,see chap4 #c1 p4 #cg74 ,the same is true in the case of the zeolitic matter of the soil4 ,there is nevertheless a distinct preference in the direction of the retention of potash as against soda2 so that in the case of alkali soils1 a large excess of potash is found to be present in the zeolitic form1 notwithstanding the presence of sometimes very large amounts of the chlorid1 sulfate and carbonate of soda4 ,this preferable retention of potash is1 of course1 of material advantage in the case of the use of soluble potash-fertilizers1 as well as in preventing the waste of the potash of the soil itself4 ,,absorption1 ,,or ,,condensation1 ,,of ,,gases ,,by ,,soils4 ,like all bodies in a state of fine division1 soils are capable of absorbing a not inconsiderable amount of various gases4 ,it may be said that in general1 other things being equal1 the amount thus condensed on the surface of the soil-grains is more or less directly proportional to the facility with which the gas is condensed by either pressure or cooling4 ,hence the very large amount of water-gas or vapor which may be absorbed by soils1 as shown in a preceding chapter4 ,but excepting perhaps the case of ammonia1 moist soils are less absorbent of gases than dry ones4 ,oxygen and nitrogen1 the main constituents of the atmosphere1 being difficultly condensable by either pressure or cold1 are absorbed by soils only to a relatively small1 yet by no means unimportant extent4 ,the condensation of oxygen within the soil-mass is doubtless of considerable importance in the processes of oxidation1 as is shown by its partial replacement by carbonic gas in the free air of the soil 7see chap4 #b1 p4 #ag74 ,the intensifying of oxidizing action caused by surface condensation is well illustrated in the case of finely divided platinum1 in which hydrogen is brought to rapid combustion when mixed with oxygen2 as well as by the effect of bedding tainted meat in charcoal powder1 when all odors of decay disappear1 both by absorption and oxidation1 ammonia and carbonic gas alone ultimately escaping through the powder4 ,carbonic dioxid and ammonia gases1 both normal constituents of the atmosphere1 and of high importance to plant nutrition1 are more readily condensable than either oxygen or nitrogen1 and consequently may be taken up by the soil in larger relative proportions4 ,especially is this the case with ammonia gas1 which is not only readily condensed by pressure1 but is also extremely soluble in water2 so much so that it rushes into a tube filled with this gas almost as quickly as though it were a vacuum4 ,water will absorb at the ordinary temperature1 under normal pressure1 about #gjj times its volume of ammonia gas2 but inasmuch as the proportion of the latter in the atmosphere amounts to only a few millionths1 the actual amount taken up can only 7as in the case of all gases7 be proportional to its proportion 7or 8partial pressure07 multiplied into its coefficient of absorption4 ,consequently1 water exposed to the ordinary air can absorb at best only a small fraction of a per cent of ammonia4 ,its presence in soils can be readily demonstrated by passing through the warmed soil a current of purified air1 which is made to bubble through ,nessler's reagent 7potassio-mercuric iodid7 solution4 ,absorption of gases by dry soils4--,perfectly dry soils are powerful absorbers of ammonia1 and their absorption of this gas1 as well as of carbonic gas1 can readily be shown by the arrangement shown on the page opposite4 ,the two tubes shown to the left are filled with carbonic gas1 those to the right with ammonia gas4 ,after being immersed in a mercurial trough1 there are introduced into each tube through the mercury small cylinders 7conveniently one cubic centimeter in volume7 consisting respectively of a very sandy soil or loose hardpan1 a gray plastic clay1 a gray clay soil or adobe1 a very black 8adobe0 clay1 and a highly ferruginous and humous soil 7from ,hawaii71 which gives the highest absorption of all2 next brown peat1 and pine charcoal4 ,the latter1 and the ferruginous soil1 were also exposed for the absorption of carbonic gas4 ,all the absorbing cylinders are first heated for an hour to #aaj;,c4 7#bah;,f7 for the purpose of expelling from them moisture1 air1 and other absorbed gases4 ,they are then quickly introduced into the tubes through the mercury and allowed to absorb the gases enclosed until the mercury columns cease to show any farther rise2 in which condition they are shown in the figure4 ,it will be seen that this absorption is a different one1 not only for each of the different substances used1 but is also differently proportioned for the two gases4 ,for it will be noted that while the clay soil has absorbed a very much larger amount of ammonia than the charcoal1 and the sandy soil has remained far behind both3 yet the charcoal has absorbed a considerably larger proportion of carbonic gas than either the clay or the sandy soil1 proving that charcoal has a strong specific absorptive power for carbonic gas1 independently of the relative size of clay and charcoal particles respectively4 ,the sandy soil shows1 by its low absorption even of ammonia gas1 the coarseness of its particles and the scarcity of clay in its composition4 ,the highest absorption of all is shown by the ferruginous soil from ,hawaii1 containing nearly #dj of ferric oxid together with #c of humus4 ,the moisture-absorption of this soil at the ordinary temperature is #ai4g per cent4 ,the difference in the absorbing power of the 7non-humous7 gray clay and gray adobe soil indicates the strong influence of humus upon the absorption2 which is still farther emphasized by the difference between the gray and black adobe1 the latter containing #a4b of humus4 ,as to the peat1 since its weight was only 4#e grams against an average of #b grams for the soils employed1 its absorptive power by weight doubtless exceeds all other substances4 ,illustration3 ,,fig4 #ea4--;,absorption of ,carbonic and ,ammonia ,gases by different ,soils4 ,while the experiment shown in the figure serves as a convenient and striking demonstration for lecture purposes1 it is of course not adapted to a direct comparison of the absorbing powers of the several substances1 because of different heights of the mercurial columns counteracting the atmospheric pressure4 ,for direct comparative measurement the tubes must be sunk in mercury so as to equalize the levels inside and outside1 since the corrected volumes obtained by calculation would not serve the purpose4 ,according to special measurements made under normal atmospheric pressure1 the writer found that a black clay soil 78adobe07 absorbed 7at #fj;,f7 over two hundred times its bulk of ammonia gas1 while under the pressure of one-fifth of an atmosphere 7as shown in the photograph7 the absorption was one hundred and twenty-three times its bulk4 ,this energetic absorption of ammonia and related gases explains the marked disinfecting effects which a covering of dry earth exerts in the case of cemeteries1 manure piles1 and earth closets4 ,but the difference between the sandy soil and the clay soil in the amount of absorption admonishes us that in all these cases1 to secure disinfection the earth to be used should contain as much clay as possible1 and should not be mere sand1 as is sometimes the case4 ,it also shows that the addition of charcoal to such materials does not increase their efficacy1 as has been supposed1 but that an equal bulk of clay would be more efficient4 ,of course1 so soon as the absorbing cylinders used for this experiment are exposed to the atmosphere1 the principle above stated in regard to 8partial pressure0 asserts itself4 ,the absorbed gases quickly begin to be given off1 and in some hours the equilibrium with the ordinary conditions of the atmosphere is re-established4 ,that the strong absorptive power of soils for ammonia is to some extent effective in maintaining the supply of this substance by absorption from the atmosphere1 cannot be doubted4 ,boussingault1 and later ,stenhouse1 determined the absorptive power of wood charcoal for ammonia to be #ij and #ih volumes respectively4 ,,the ,,composition ,,of ,,gases ,,absorbed ,,from ,,the ,,atmosphere ,,by ,,various ,,solids4 ,in #ahfd and #ahfe ,reichardt and ,blumtritt#ii investigated elaborately the composition of gases driven off by heat from various powders1 including soils1 exposed to the atmosphere4 ,all the substances examined were therefore 8air-dry10 therefore to a certain extent moist2 and the presence of this aqueous vapor of course modifies in a measure the results that would have been obtained had the materials used been exposed to dry air only4 ,they found that1 as had already been stated by previous observers1 the presence of capillary water diminishes materially the absorption of gases1 especially of those not as easily absorbed by water as are carbonic gas and ammonia4 ,contrary to what might have been expected from the more ready condensation of oxygen by pressure or cold1 in nearly all cases nitrogen is absorbed to a greater extent than oxygen1 and sometimes exclusively so2 so that in some cases the latter was found to be present only in traces1 as will be perceived from the subjoined table3 ,,composition ,,of ,,gases ,,absorbed ,,from ,,the ,,atmosphere ,,by ,,various ,,powders #ajj #ajj ,grms ,vol's ,substance4 gave cc4 gave ,gas4 ,vol's4 ,gas4 ---------------------------------------- ------ ,charcoal1 coniferous1 air dry #af4ba 8 moistened and air-dried #adj4aa #ei4j 8 ,lombardy ,poplar #dff4ie #aie4d ,peat #afb4eh ,garden ,earth1 moist #ac4gj #ai4i 8 8 air-dried #cj4bh #ec4f ,river ,silt1 air-dried #dj4ec #dh4jg 8 8 slightly moistened #bd4ab #bi4b 8 8 air-dried #bf4eb #cj4je ,clay1 long exposed #be4eh #ci4je 8 slightly moistened #bh4fb #ce4jh ---------------------------------------- ------- ,ferric ,hydrate1 commercial #bea4ei #bge4j 8 8 freshly #cge4ed #cjh4f precipitated1 air-dried ---------------------------------------- ------- ,ferric ,oxid1 ignited #ci4d #eb4d ,aluminic ,hydrate1 air-dried #fi4jb #hb4j 8 8 dried at #ajj;,c4 #aj4hc #ac4f ,prepared ,chalk1 #ahfd-fe #dc4dh #eb4d 8 8 #ahfe #ch4ih #dh4j ---------------------------------------- ------- ,calcic ,carbonate1 precipitated1 #fe4ji #ahfd-fe 8 8 precipitated1 #ea4ec #eb4j #ahfe-ff ---------------------------------------- ------- ,magnesic ,carbonate #gbi4ba #abd4i ,gypsum1 finely powdered #ag4bf ---------------------------------------- ------- #ajj vol's gas contained ------------------------------- ,substance4 ,nitrogen,oxygen,carbonic ,carbon ,dioxid ,monoxid ---------------------------------------- ----------------------- ,charcoal1 coniferous1 air dry #ajj4jj #j4j #j4j #j4j 8 moistened and air-dried #he4fj #b4ab #i4ae #c4ac 8 ,lombardy ,poplar #hc4fj #j4j #af4ej #j4j ,peat #dd4dd #d4fj #ej4if #j4j ,garden ,earth1 moist #fd4cd #b4he #bd4jf #h4ge 8 8 air-dried #fd4gj #b4jd #cc4bf #j4j ,river ,silt1 air-dried #fg4fi #j4j #ah4fa #ac4gj 8 8 slightly moistened #fg4cd #j4j #cj4ef #b4aj 8 8 air-dried #fg4dj #i4ji #af4jg #g4dd ,clay1 long exposed #gj4ag #d4ga #be4ab 8 slightly moistened #ei4ei #f4ci #cd4jb ---------------------------------------- ----------------------- ,ferric ,hydrate1 commercial #cc4bf #a4dc #fe4ca #j4jj 8 8 freshly #bf4bi #c4he #fi4hf #j4jj precipitated1 air-dried ---------------------------------------- ----------------------- ,ferric ,oxid1 ignited #hb4hg #ac4da #c4gb #j4jj ,aluminic ,hydrate1 air-dried #dj4fj #j4jj #ei4dj 8 8 dried at #ajj;,c4 #hc4ji #af4ia #j4jj ,prepared ,chalk1 #ahfd-fe #ajj4jj #j4jj #j4jj 8 8 #ahfe #gd4di #ae4di #aj4jb ,calcic ,carbonate1 precipitated1 #hj4ha #ai4ai #j4jj #ahfd-fe ,calcic ,carbonate1 precipitated1 #gg4cg #ae4ji #g4ed #ahfe-ff ,magnesic ,carbonate #fc4ib #f4gb #bi4cf ,gypsum1 finely powdered #hj4ie #ai4je #j4jj ---------------------------------------- ----------------------- #ii ,journal fr praktische ,chemie1 ,vol4 #ih1 p4 #afg4 ,discussion of the ,table4--,it will be observed that in this table1 the largest amount of total gas given off by equal weights of any one substance was in the case of carbonate of magnesia2 but it is quite probable that in part1 at least1 this large amount of gas was due to the evolution of carbonic gas from the easily decomposable carbonate2 the more as the analysis of the gases shows over #bi of carbonic gas4 ,but the highest absorption by equal volumes of any substance is shown by the ferric hydrate2 next to this by the light poplar charcoal1 and next by the carbonate of magnesia4 ,the high absorptive power here shown by the ferric hydrate is of great interest in connection with the facts already stated regarding the absorption of moisture and ammonia by ferruginous soils 7see page #bgd1 this chapter72 and the fact that the larger proportion of the gas--as much as #gj in one case--consisted of carbonic gas1 is particularly interesting in the same connection4 ,both in the amount of gas contained1 and in the proportion of carbonic gas therein1 the ferric hydrate exceeds even peat1 the representative of humus in soils4 ,it will1 however1 be noted that in the garden soil1 also1 the proportion of carbonic gas is very large1 while that of oxygen is very low4 ,it is curious to note that in very few cases the proportion of oxygen to nitrogen is the same as in the atmosphere2 in most cases the nitrogen predominates considerably beyond its normal proportion1 and in two cases1 that of charcoal and of calcic carbonate 7whiting71 the gas was found to consist of pure nitrogen4 ,we are forced to conclude that the substances here enumerated1 as a rule1 condense oxygen in smaller proportions than they do nitrogen1 or carbonic gas4 ,as regards the carbon monoxid mentioned in the table1 it is doubtful that it was contained as such in the substance originally examined2 it may readily have been formed under the influence of the heat required in expelling the gases from the substances containing organic matter4 ,among the important results shown in the table1 is the comparative determination of the gases in moist1 and in dry garden earth1 showing that in the moist earth the amount of gas absorbed ranged from less than one-half down to almost one-fourth that absorbed by the dry4 ,the importance of these differences in the case of the fallow can readily be appreciated4 ,the changes in the absorptive power brought about by wetting and drying1 as shown in the above table1 are very insignificant4 ,in the case of the charcoal1 soil and silt the diminution may fairly be assumed to be caused by the deposition of soluble salts on the surface1 partly clogging the pores4 ,in the case of the clay as well as in that of the river silt1 the inevitable content of organic matter in process of decomposition has doubtless influenced the result1 as is suggested by the increase of carbonic gas4 ,that prepared chalk should in one case contain exclusively nitrogen gas1 in the other case mixed gases1 seems to indicate a difference in the air to which it is exposed1 or in the water employed in its preparation2 the latter case agreeing substantially with the results obtained from the precipitated carbonate4 ,in both 7as well as in the carbonates of barium and strontium71 the absorption of carbonic gas is very small1 or nil4 ,it thus appears that for the condensation of carbonic dioxid gas1 ferric and aluminic hydrates are prepotent among mineral substances2 while clays1 river silts and soils may always be expected to contain relatively large proportions of this gas in absorption4 ,,the ,,air ,,of ,,soils4 ,the ,empty ,space in ,soils4--,in dry soils the empty space1 usually amounting to from #ce to #ej per cent of its volume1 is filled with air2#ajj in moist or wet soils the space unoccupied by water is similarly filled4 ,hence when soils are in their best condition for the support of vegetation 7chap4 #aa1 p4 #bjb71 about one half of their interstices is filled with water1 the other half with air4 ,actual measurements of the amount of air contained in well-cultivated garden soil have been shown by ,boussingault and ,levy to range between #aj1jjj and #ab1jjj cubic feet per acre1 substantially agreeing1 therefore1 with the above statement4 ,in uncultivated forest soil1 on the contrary1 they found only from somewhat less than #djjj to #fjjj cubic feet of air per acre4 ,extended observations since carried out by ,wollny1 ,ebermayer1 and others have in general confirmed the earlier observations1 while adding greatly to their significance in respect to their relations to plant growth1 and to the process of humification and soil-formation4 #ajj ,the normal composition of atmospheric air is given on p4 #af1 chap4 #b4 ,as a matter of course1 when water evaporates from the soil in drying1 its place is taken by air so far as it is not filled by capillary water drawn from below4 ,functions of ,air in ,soils4--,that roots require for the performance of their vegetative functions the presence of oxygen1 has already been discussed2 but there can be no question that the higher productiveness of well-cultivated soils is largely due to the greater and readier access of air to the roots4 ,apart from this direct function1 however1 the presence of oxygen in the soil serves other important purposes1 and among these doubtless the most dominant is the promotion of the oxidation of the organic matter of the soil through the agency of micro-organisms2 and more particularly that of nitrification1 which chiefly governs the supply of nitrogen to non-leguminous plants4 ,in the case of leguminous plants1 the presence of air as a furnisher of nitrogen as well as oxygen is absolutely essential4 ,the injurious effects of insufficient aeration of the soil have been repeatedly referred to already 7pp4 #de1 #gf74 ,in water-logged soils reductive fermentations are soon set up1 and the nitrates of the soils are reduced partly with the evolution of nitrogen gas1 partly to ammonia2 while their oxygen is consumed to supply the demands of the roots4 ,ferric oxid is reduced to ferrous carbonate1 sulfates to sulfids2 thus deranging the whole process of plant-nutrition and absorption of plant-food4 ,if continued for any length of time these conditions end in the death of the plant4 ,too much importance cannot therefore be attached to the proper aeration of the soil and subsoil4 ,excessive ,aeration2 ,compacting the ,soil4--,on the other hand1 excessive aeration of the soil may be injurious in causing a serious waste of moisture2 especially in arid climates1 where the hot1 dry winds may readily destroy the germinating power of the swollen seed when the seed-bed is too loose and open1 and later may injure or destroy the feeding roots4 ,the abundant growth of grain often seen in the tracks of a wagon carrying the centrifugal sower1 when the stand in the general surface is very scanty1 is usually due to the consolidation of the seed-bed1 and suggests at once the well-known efficacy of light rolling to insure quicker germination and a better stand4 ,similarly1 the rolling of grain fields in spring is often the saving clause for a crop in dry years4 ,but such needful consolidation must not1 of course1 be carried to the extent of creating a surface crust which would subsequently serve to waste the subsoil moisture4 ,hence1 the soil-surface should be rather dry when rolling is resorted to4 ,the pressing of the earth around transplanted plants1 similarly1 is a needful precaution1 not only with respect to the drying-out of the soil1 but also to insure close contact between the roots and the soil4 ,the ,composition of the ,free ,air of the ,soil usually differs from the air above1 in that besides being saturated with moisture1 its nitrogen-content is slightly increased 7by one-half to over one per cent72 the oxygen-content on the other hand1 is diminished1 being in part 7sometimes nearly to the extent of one-half of its volume7 replaced by carbonic gas1 derived partly from its secretion by the roots1 partly from the oxidation of organic substances4 ,it naturally follows that the richer the soil in the latter1 the more carbonic gas will be formed under favoring conditions2 so that in freshly-manured land the amount of oxygen transformed into carbonic gas will be greatest1 while in the surface-soil of ordinary fields1 carbonic gas rarely reaches to as much as one per cent4 ,in all cases1 however1 the content of carbonic gas in the air of the soil is materially higher than that of the air above it1 and thus serves to intensify greatly the solvent and disintegrating effect of the soil water upon the soil materials 7see chap4 #b1 p4 #ag74 ,the soil-mass itself1 however1 retains carbonic dioxid with considerable tenacity1 so that it is not possible to wash it out completely by filtering water through it4 ,when water containing carbonic gas in solution is filtered through the soil1 the gas is sometimes completely absorbed1 the water passing off free from gas4 ,the presence of free carbonic gas in soils is readily demonstrated by passing through the warmed soil a current of air1 which is then made to bubble through lime water2 a clouding of the latter1 and the ultimate formation of a precipitate of calcic carbonate1 proves the presence of the gas1 and may also serve to measure its amount4 ,from the fact that the free air in normal soils may contain as much as one-fortieth of its bulk of carbonic gas1 besides what may be contained in the condensed form1 we may conclude that this gas is formed within them with considerable rapidity2 for otherwise1 in view of the free communication and diffusion with the outer air1 such large amounts could not be maintained in the surface-soil4 ,doubtless a considerable proportion of the carbonic gas normally contained in the atmosphere is thus supplied from within the soil itself4 ,relation of ,carbonic ,gas to ,bacterial and ,fungous ,activity4--,it has been fully demonstrated by the researches of ,koch1 ,miquel1 ,adametz1 ,fuelles1 ,wollny and others1 that the formation of carbonic gas in the soil is not a purely chemical oxidation process1 but is essentially dependent upon the presence and life-activity of numerous kinds of organisms1 bacterial as well as fungous4 ,the crucial proof of this fact is that the presence of any antiseptic diminishes1 and if exceeding certain proportions completely suppresses1 the formation of carbonic gas2 while on the other hand all conditions known to be favorable to the life of such organisms1 viz41 the proper conditions of temperature and moisture 7varying with different kinds71 increase the formation of the gas4 ,such formation is of course1 however1 conditioned upon the presence of oxygen4 ,in the case of most bacteria1 there is a certain limit beyond which the presence of their own product exerts an injurious or repressive effect upon their activity2 so that if the gas accumulates beyond that limit1 the rate of its formation decreases despite of otherwise favorable conditions4 ,it follows that the best life-conditions of these organisms 7even when anerobic7 cannot be fulfilled below a certain limited depth in the soil2 and all observations show that their number decreases very rapidly with increasing depth 7see chap4 #i1 p4 #adb71 varying with the perviousness of the soil1 but rarely exceeding four or five feet in the humid regions2 though doubtless found at greater depths in the arid climates4 ,it is also obvious that the use of any antiseptic or poisonous materials on the field or in the manure pile will tend to disturb and restrain the useful activity of these organisms4 ,putrefactive ,processes4--,carbonic gas is formed also1 but to a much more limited extent1 in putrefactive processes1 occurring in the absence1 or with only limited access1 of air or oxygen4 ,these processes likewise are conditioned upon the presence or activity of 7largely anerobic7 bacteria2 but they should not occur in normally constituted1 and especially in tilled soils1 being as a rule inimical to the growth of cultivated plants 7see chap4 #i1 p4 #ade74 ,,chapter ,,xv4 ,,the ,,colors ,,of ,,soils4 ,the natural coloration of soils forms a prominent part of the characters upon which farmers are wont to base their judgment of land quality2 hence the origin and value of soil-colors deserve consideration4 ,black ,soils4--,from the oldest times down to the present a 8rich1 black soil0 has commanded attention and approval4 ,the black and brown-black colors being almost invariably due to the presence of much humus 7very rarely to an admixture of carbon graphite1 of magnetic oxid of iron1 or sesquioxid of manganese71 it is obvious that the farmers' judgment coincides with a high estimate of the agricultural value of humus4 ,a discussion of this point will be found in another place2 but the popular judgment is based quite as much upon the experience had in the advantages that usually accompany the presence of humus4 ,it largely characterizes low grounds1 and therefore alluvial lands1 whose richness is due to far more general causes4 ,but the shade of the blackness seen in the soil deserves and usually receives close consideration4 ,if tending toward brown1 acid humus or 8sour0 land is indicated2 unless indeed the surface soil should be bodily derived from decayed wood1 as in the primeval forests4 ,forest soils in general are usually dark-tinted for some inches near the surface1 owing to the presence of leaf mold1 and mostly have an acid reaction4 ,but the black tint is equally welcome to the land-seeker when seen outside of alluvial and forest areas4 ,belts of 8black lands0 appear on hillsides and plateaus2 and these lands1 though clearly not alluvial1 are also found to be preminently productive2 witness the upland prairies of the western and southern ,united ,states4 ,these black soils are always characterized by the presence of a full supply of lime in the form of carbonate1 under the influence of which the most deeply black humus is formed4 ,in other words1 the jet black tint is indicative of calcareous lands2 and these1 as will be more fully shown below1 are almost always highly productive4 ,from both points of view1 then1 the favorable judgment passed upon black soils by practical men is justified4 ,but it is not necessarily true that soils showing no obvious black tint are poor in humus2 for in strongly ferruginous or 8red0 soils its tint is frequently wholly obscured1 though when still visible it gives rise to the laudatory name of 8mahogany land10 which every farmer considers a prize4 ,of course then it would be wholly incorrect to judge of the agricultural value of land from its humus-content alone2 for its color may be entirely imperceptible and yet its amount and nitrogen content be fully adequate to the requirements of thrifty vegetation4 ,gray and even whitish soils very frequently fall within this category in the arid region4 ,the black tint is also favorable to the absorption of the sun's heat1 and is therefore conducive to earlier maturity than is to be looked for in light-tinted lands similarly located4 ,wollny 7,forsch4 ,agr4 ,phys4 ,vol4 #ab1 #ahhi1 p4 #che71 discusses the influence of color on soils in relation to moisture and content of carbonic acid4 ,the results show in general simply the effects due to increase of temperature when the soils are either darker-colored throughout1 or made so superficially4 8,red0 ,soils4--,next to a black soil1 a 8red0 one will usually command the instinctive approval of farmers4 ,the cause of this preference is not as obvious as in the case of the black tints2 but the general consensus of opinion requires an examination of its claims4 ,it is of course easy enough to adduce examples of very poor 8red0 soils1 derived from ferruginous sandstones that supply little else than quartz and ferric hydrate2 the ,cotton ,states supply cogent examples in point1 as do also the lower ,foothills of the ,sierra ,nevada of ,california4 ,it is not1 therefore1 the iron rust or ferric hydrate that renders the land productive2 but its presence is a sign of some favorable conditions4 ,first among these is1 that ferric hydrate cannot continue to exist in badly drained soils2 a 8red0 soil is therefore a well-drained one1 and this is probably one of the chief causes of the popular preference4 ,the 8white land0 sometimes seem in tracts otherwise colored with iron1 is distinctly inferior in production to the red lands2 and examination will generally show that from some cause1 such white lands have been subjected to the watery maceration which proves so injurious 7see chap4 #c1 p4 #df1 chap4 #ab1 p4 #bca74 ,that finely-diffused ferric hydrate has a very high power of absorbing moisture as well as other gases of the atmosphere1 has been shown in the preceding chapter2 it stands in this respect next to humus itself1 and hence highly ferruginous soils need not contain as much humus as 8white0 soils from this point of view4 ,like humus1 also1 it renders heavy clay soils more easily tillable4 ,origin of ,red ,tints4--,where crystalline rocks prevail1 the red tint usually indicates the derivation from the weathering of hornblende2 implying also1 outside of the tropics1 the presence of sufficient lime in the land4 ,such lands are naturally preferred to those of lighter tints derived from purely feldspathic rocks 7see chap4 #c1 p4 #cb71 although they may be poorer in potash than the latter4 ,but the red tint has also its intrinsic advantages in the more ready absorption of the sun's heat by the colored than by a white surface4 ,this is probably the chief cause of the higher quality of wines grown on red hillsides in the middle and northern vine districts of ,europe1 where everything that aids earlier maturity is of the greatest importance4 ,the function of ferric oxid as a carrier of oxygen 7chap4 #d1 p4 #de7 probably also aids nitrification4 8,yellow0 lands owe their tint1 of course1 to smaller amounts of ferric hydrate1 but share more or less in the advantages of the 8red40 ,white soils1 or more properly those having very light gray tints1 are not usually looked upon with favor1 especially in the humid region4 ,the causes of the unfavorable judgment current among farmers in respect to white soils has already been partially explained in the discussion of the black and red tints4 ,the light color means the scarcity or absence of both humus and ferric hydrate1 and usually implies that the soil has been subject to reductive maceration through the influence of stagnant water2 reducing the ferric hydrate to ferrous salts1 oxidizing away the humus1 and accumulating in the form of inert concretions most or all of the lime1 iron and phosphoric acid of the soil mass 7see chap4 #c1 p4 #df1 chap4 #aj1 p4 #ahd74 ,the term 8crawfishy10 so commonly applied to white soils in the eastern ,united ,states1 expresses well the usual condition of the white soils of that region2 which are very commonly inhabited by crayfish1 whose holes reach water a few feet below ground1 and are surrounded on the outside by piles of white subsoil mixed with 8black gravel0 or concretions of bog iron ore4 ,it is needless to say why such lands cannot command the favorable consideration of the farmer2 they cannot as a rule be cultivated without previous drainage1 and even after that will usually prove unthrifty1 8raw10 and in immediate need of fertilization by green-manuring1 and the use of phosphates4 ,in the arid region1 lands of this character are of rare occurrence1 while 7as has been explained above1 chap4 #h1 p4 #ace71 the light gray or 8white0 tints are there a very common characteristic of even the very best soils4 ,it is true that they are poor in humus and in finely diffused ferric hydrate2 but their 8light0 texture renders the presence of humus for this purpose less needful1 and as stated elsewhere 7see chap4 #h1 p4 #ace71 the high nitrogen-content of arid humus renders a smaller supply adequate for vegetative purposes4 ,as to iron1 its presence being more important as a sign of good drainage and aeration than directly1 its absence from soils of great depth and loose texture is of no consequence2 especially when the heat-absorption which it favors is not only not needed1 but is usually already in undesirable excess during the hot summers4 ,white ,alkali ,spots4--,in the valleys of the arid region1 however1 very white spots commonly indicate the prevalence of alkali salts1 and to that extent are an unfavorable indication2 especially when coupled with the occurrence of black rings or spots1 which indicate the presence of black alkali or carbonate of soda 7see chap4 #bb74 ,,chapter ,,xvi4 ,,climate4 ,heat and ,moisture are the main governing conditions of plant growth4 ,in a preceding chapter the relations of soils and plant growth to water have been considered2 in the present one the relations of both moisture and heat to soils and plants will be discussed2 and to do this intelligibly to those not making a specialty of such studies1 it becomes necessary to introduce1 first1 a summary consideration of the subject of climate4 ,climatic conditions control1 and to a great extent determine1 the industrial pursuits of every country2 all the more so as the rapid communication and transportation by means of modern appliances now brings every part of the globe in competition with every other4 ,the question is not now what it may be intrinsically possible to do under certain climatic and geographical conditions1 but whether these things can be done with a reasonable prospect of profit and commercial success1 in competition with other countries offering more or less of similar possibilities4 ,while it is true that the cost of labor frequently enters most heavily into such problems1 yet favorable or unfavorable climatic or soil-conditions may in many cases turn the scale4 ,thus the high price of labor and fuel on the ,pacific coast of the ,united ,states would at first blush seem to render competition with ,europe and the ,east in the production of beet sugar commercially impossible2 yet exceptionally favorable climatic and soil-conditions concur to turn the scale in favor of ,california at least1 so as to have placed that state at the head of the sugar-producing states of the ,union4 ,a general understanding of the climatic conditions which concern the ,united ,states more or less directly1 is therefore needful to an appreciation of their agricultural possibilities4 ,climatic ,conditions4--,the factors usually mentioned as constituting climate are temperature1 rainfall and winds4 ,since the latter two factors1 however1 are themselves merely the result of heat conditions1 it is proper to discuss from the outset the origin and mode of action of heat4 ,,temperature4 ,the temperature of stellar space outside of the atmosphere is known to be very low4 ,the increasing cold as we ascend to greater heights1 is a fact familiar to all4 ,langley has calculated upon the basis of observations made at the summit and foot of ,mount ,whitney in ,california1 that the temperature of space lies near #bjj ,cent4 7#cfj ,f47 below the freezing point of water2 and this would be the temperature near the ,earth's surface1 were it not for the surrounding atmosphere4 ,the latter absorbs but a small amount of the sun's direct heat rays 7which are of high intensity71 as they penetrate it to the ,earth's surface4 ,but as the earth's surface is warmed1 the heat rays of low intensity which it emits cannot pass back through the atmosphere to the sun or to outer space2 they are 8trapped10 as it were1 by the dense air resting near the earth's surface1 which is then warmed partly by the radiation from1 partly by direct contact with1 the soil4 ,it is to the existence of our atmosphere1 then1 that the possibility of our animal and vegetable life in their present form is due2 and a decrease of the trapping effect on the sun's heat rays makes itself quickly felt when ascending1 either in balloons or on high mountains4 ,moreover1 it is well known to mountain climbers that at great elevations the sun's heat is extremely intense at noon2 even though the temperature may fall to the freezing point at night1 owing to the failure of the thin air to prevent the radiation back into space of the heat absorbed during the day4 ,on the high plateaus of the ,andes and of ,asia1 therefore1 very extreme climates prevail1 on account of the great range of temperature between day and night4 ,ascertainment and ,presentation of ,temperature-,conditions4--,the proper understanding of the temperature conditions of any locality or region is by no means a simple matter4 ,shall we study the daily1 monthly1 or annual changes of temperature1 or the means deduced from either or all of them1 in order to gain a clear insight into the climatic conditions that control crop production and health conditions8 ,the ,annual ,mean ,temperature not a ,good ,criterion4--,since one and the same figure may result equally from the averaging of two widely divergent data1 and from such as are close together1 it is clear that the mean annual temperature cannot be a proper criterion of the agricultural adaptations of a country4 ,thus an average temperature of #fj ,f4 might result1 equally1 from the averaging of #fe and #ee degrees1 or from taking the mean of #ae and #aje degrees2 yet the respective cultural adaptations would be widely different4 ,extremes of ,temperature are ,most ,important4--,it is1 on the contrary1 rather the extremes of temperature1 more particularly of cold1 but frequently also of heat1 together with the total amount of heat available during the growing season1 that determines such adaptation so far as temperature is concerned2 for no culture plant can be successfully grown where the temperature during winter even occasionally falls for more than a few hours below the point which it can resist2 and for each plant there is a certain aggregate requirement of heat to carry it from germination to fruiting4 ,even different varieties of one and the same plant differ materially in the latter respect1 so that it is very important that in the selection of varieties to be grown1 this factor should be taken into consideration4 ,it cannot be too strongly urged that the comparison of annual means of temperature1 so commonly made by promoters of colonization schemes1 must not be taken as a guide either in the estimate of cultures in which the immigrant may desire to engage1 or by those in search of a climate adapted to their health-conditions4 ,seasonal and ,monthly ,means4--,the statement of the mean temperatures of the conventional four seasons--spring1 summer1 autumn and winter--afford a much clearer conception of climatic adaptations2 provided always that the extreme temperatures be considered at the same time4 ,with the same understanding1 the monthly means are still more instructive2 but here again1 it is most essential that the distribution and amount of rainfall in each be regarded at the same time1 since the most desirable temperature is of no avail without the moisture required for vegetation4 ,in some cases1 e4 g41 that of ,california1 it becomes necessary for practical purposes to regard the 8season10 and not the calendar year1 as the unit or reference for crop production4 ,there the crops depend upon what rainfall may occur from ,october to ,may1 there being no summer rains of agricultural significance1 and outside of irrigated lands1 almost all vegetation save that of trees being in abeyance4 ,in ,india1 there are two distinct growing seasons 78kharif0 and 8rabi071 corresponding to the two 8monsoon0 seasons2 and no matter how much rain may fall during one1 almost total failure may occur in other tropical and arid sections of that country4 ,the ,daily ,variations are of interest chiefly with respect to health conditions1 since most plants are more adaptable in this respect than the average man4 ,,rainfall4 ,distribution ,most ,important4--,the summary statements of the annual rainfall are almost equally as deceptive as are those of annual mean temperature1 since quite as much depends on the manner in which it is distributed through the year1 as upon its absolute amount2 and also upon the manner of its fall4 ,thus ,central ,montana has the same aggregate annual rainfall as the country surrounding the ,bay of ,san ,francisco1 viz4 about #bd inches2 but while in the ,franciscan climate this amount of rain falls during one-half of the year1 and that the growing season1 enabling crops to be grown without irrigation1 in ,montana the rainfall is distributed over the entire season1 so that irrigation is absolutely essential for the successful production of crops4 ,this so much the more as1 while the winter snowfall is very light1 the rains of summer are largely torrential1 running off the surface in muddy floods and giving little time for absorption into the soil4 ,farther west1 in ,washington1 where grain crops are largely grown without irrigation1 the sowing of winter grain is impracticable because the dry summer is immediately followed by the very light snowfall of winter1 which falls on dry ground4 ,fall-sown grain would thus simply lie dormant in the ground through the winter1 with great liability to injury from stress of weather in early spring1 apart from the depredations of birds and rodents4 ,hence grain is always sown there in spring only4 ,these examples may suffice to show that summary statements of either temperature or rainfall by yearly means are of little practical interest to the farmer4 ,what he needs to know is whether or not sufficient rains to mature a full crop are likely to fall during the time that the growing temperature prevails2 and what are the minima and maxima of temperature--heat and cold--that his crops will be called upon to endure4 ,,winds4 ,the third climatic factor mentioned1 the winds1 though proverbial for their unreliability and inconstancy1 are not only very incisive in their action1 but also to a considerable extent of very definite local or regional occurrence and significance4 ,moreover1 their occurrence1 direction1 temperature and moisture-condition can1 in regions whose climatology has been reasonably well studied1 be foretold with sufficient accuracy to be of great use to the farmer4 ,heat the ,cause of ,winds4--,as already stated1 the primary cause of all winds is heat1 substantially on the principle according to which draught is created in our domestic fires4 ,the hot air rising creates an indraught from all directions1 especially from that which it can most readily come2 viz41 from the ocean1#aja or from level lands1 rather than across mountain chains4 ,hence the sea-breeze in the after part of the day1 when the land has become heated2 while the sea1 requiring a much larger amount of heat to change its temperature to a similar extent1 remains relatively cool4 ,but at night the earth cools more rapidly than the sea1 by radiation2 hence toward evening the sea-breeze dies down1 and toward and after sunset the land-breeze takes its place4 #aja ,a striking case in point is the regular wind which in summer blows through the 8,golden ,gate10 a gap in the ,coast ,range connecting the ,pacific ,ocean directly with the great interior valley of ,california1 along the bays of ,san ,francisco1 ,san ,pablo1 and ,suisun4 ,the great interior valley and adjacent mountain slopes becoming intensely heated during the rainless summer1 the ascending air is replaced by a steady indraught from the sea1 which is bordered by a belt of cold water causing fogs along the coast4 ,the fogs are quickly dispelled on reaching the edge of the valley near the middle of its length2 whence steady breezes blow northward and southward1 up the valleys of the ,sacramento and ,san ,joaquin respectively4 ,these winds1 popularly often1 but erroneously1 called trade-winds1 are really 8monsoons0 similar in their origin to those of ,india1 which1 when coming from the sea cause rains1 but when from the heated land itself are hot and dry2 as in the case of the sirocco of ,italy and ,north ,africa1 the terral of ,spain and the northers of ,california4 ,the principle of this local change of winds1 together with the rotation of the earth1 the absorption of moisture by air1 and the fact that the latter becomes cooler when it expands on rising and warmer when it is compressed by descending1 serves to explain all the major phenomena usually observed in connection with winds4 ,the air of the equatorial belt1 heated throughout the year1 necessarily rises and creates an indraught from both north and south2 but since the air thus flowing in has a lower rotary velocity than the earth's surface at the ,equator1 it lags behind and so gives rise to northeast and southeast winds1 respectively1 between the two tropics and the equatorial belt4 ,these regular winds1 from the aid they give to commerce in passing from continent to continent1 are known as the trade winds4 ,on the other hand1 the air that has risen from the hot equatorial belt1 cooling by expansion as it rises and flowing northward and southward from the ,equator1 on descending as it mainly does into the temperate zones1 has a higher rotary velocity than the land-surface and so tends to give rise to southwest and northwest winds in the northern and southern hemispheres respectively4 ,at sea1 on coasts and in level inland regions to windward of mountain chains1 such winds are often quite regular during a portion of the year4 ,cyclones4--,but local disturbances arising from heated land areas or mountain slopes1 as well as wide atmospheric changes whose causes are not fully understood1 give rise to waves of alternating high and low barometric pressure1 largely converting rectilinear or slightly curved wind-motion into whirls or 8cyclones0#ajb ranging from a thousand to over two thousand miles in diameter4 ,these in the case of low-pressure waves or centers1 toward which the air flows from the outside1 revolve in the direction contrary to the movement of the hands of a clock1 and commonly produce rain in their east portion4 ,a high-pressure wave or center1 from which the air naturally flows toward the outside1 will usually bring about an 8anti-cyclone0 area with fair1 and in winter cold 78blizzard07 weather1 the direction of the whirl being1 in this case1 the reverse1 or in the same direction as the hands of a clock4 ,both cyclones and anti-cyclones move in ,north ,america from west to east1 mostly entering from the ,pacific ,ocean off the northwest coast and traversing the continent with a slight southeast 7or in the case of cold weather almost south7 trend1 with a velocity of twenty to thirty miles an hour2 until upon reaching the region of the ,great ,lakes they generally turn northeastward and pass into the ,atlantic ,ocean from the ,new ,england and ,canada coasts4--,it is upon these general facts1 roughly outlined here1 that the weather forecasts are in the main based2 taking into consideration1 of course1 the local or regional conditions1 topography1 etc41 which modify the application of the general rules4 #ajb ,this designation is popularly and incorrectly applied to the comparatively limited1 but very violent and destructive rotary storms or whirlwinds which originate locally on the heated plains of the ,middle ,west of the ,united ,states1 and are almost always accompanied by violent electric phenomena4 ,these should properly be called tornadoes4 ,at sea such whirlwinds give rise to waterspouts1 in deserts to sand storms4 ,in the southern hemisphere1 the air-movements substantially correspond to those observed in the northern1 so far as not modified by mountain chains2 as is especially the case in ,south ,america4 ,,influence ,,of ,,topography4 ,rains to ,windward of ,mountain ,chains4--,the surface features or topography of the regions traversed by the air currents or winds may materially modify both their direction and their physical condition1 especially as to moisture and temperature4 ,mountain chains may deflect them1 or1 causing the air currents to rise on their slopes1 and thus to cool by expansion1 the moisture these bring with them from the sea may be partially1 or sometimes almost wholly1 deposited in the form of rain or snow2 chiefly on the windward slopes4 ,then1 continuing across the range1 the air deprived of most of its moisture cannot readily yield up more2 hence the scarcity of rain--8arid climate0--under the lee of mountain chains2 as in the ,great ,basin between the ,sierra ,nevada and ,cascade ranges on the one hand and the ,rocky ,mountains on the other1 and also on the ,great ,plains under the lee of the latter4 ,the abundant rainfall between the ,mississippi river and the ,atlantic coast is due to the moist winds coming from the warm waters of the ,gulf of ,mexico and ,caribbean sea1 whose access is not interfered with by any cross-ranges of mountains4 ,but the ,great ,plains lying between the ,mississippi and the ,rocky ,mountains are not within the sweep of the ,gulf winds1 whose trend is ,,sw to ,,ne2 while they are equally out of reach of moisture from the ,pacific1 all that having been successively deposited on the intervening mountains2 hence their deficient rainfall4 ,northward of the temperate zone the rainfall generally decreases as we approach the arctic regions2 except where the influence of warm ocean currents to windward creates comparatively local exceptions1 as in the case of ,norway and ,alaska4 ,illustration3 ,,fig4 #eb4--;,composite ,curve showing distribution of ,rainfall in ,europe1 ,africa and ,america projected on #ajj ,meridian ,w4 ,l4 ,the general ,distribution of ,rainfall on the globe is well shown in the annexed diagram1 which is copied by permission of the author from his treatise on the 8,evolution of ,climates10#ajc and represents the mean deduced from data given in the ,atlas of ,meteorology by ,j4 ,g4 ,bartholomew4 ,it is a composite curve derived from the consolidation of four curves showing the distribution of rainfall1 viz41 on the meridians of #bj;,e4,l42 the west coasts of ,europe and ,africa2 the #cjth meridian ,w4,l41 in the ,atlantic ,ocean2 and the west coasts of ,north and ,south ,america1 projected on the plane of the #ajjth meridian ,w4,l4 ,the latter curve corresponds with remarkable closeness to the mean curve here given4 8,it is not intended that these curves should include the rainfall upon meridians on which the distribution in belts is interrupted by continental influences1 and by the irregular oblique belts of rain on the east coasts40 ,but it presents an admirable generalization upon which1 as a basis1 the local disturbances may be studied4 #ajc 8,the ,evolution of ,climates02 by ,marsden ,manson1 ,july1 #aijc2 also ,amer4 ,geologist1 ,aug4-,oct4 #ahig4 ,it will be noted that the maximum of rainfall in the tropical rain-belt lies several degrees to northward of the equator1 owing doubtless to the greater land area in the northern hemisphere4 ,there is thus1 on the whole1 a narrower belt of deficient rainfall or aridity between the tropical and northern temperate rain-belts1 than in the southern hemisphere4 ,the southern temperate rain-belt touches only the extreme ends of ,south ,america1 ,africa and ,new ,zealand2 elsewhere on the ocean it has not been sufficiently observed as yet4 ,the zones of rainfall and aridity are1 however1 known to be subject to seasonal oscillations of several degrees in latitude1 owing to the obliquity of the plane of the ecliptic1 which shifts its position upon that of the equator4 ,ocean ,currents4--,since water as a fluid is subject to the same circulatory motions which cause winds1 it is to be expected that ocean currents should exist corresponding to those of the air1 as characterized in general above4 ,but as water warms so much more slowly than air1 its circulation would be comparatively insensible were it not for the effects produced by the air currents upon the surface of the sea1 combined1 as in the case of the winds1 with the effects of the rotation of the earth4 ,without going into the details of the ocean currents in the tropics1 it may suffice to say that owing partly to the moving and warming effects of winds1 partly to the natural circulatory motion of the water1 two great warm currents flow from the tropics northward1 materially modifying what would otherwise be the climates of the coasts they touch4 ,the ,gulf ,stream4--,the current most generally known is the ,gulf ,stream1 flowing partly from the ,gulf of ,mexico and the ,caribbean ,sea1 partly from outside of the same along the chain of the ,lesser ,antilles1 along the southeast coast of the ,united ,states 7,florida1 ,georgia and ,south ,carolina72 but owing to its greater rotational velocity it is soon1 like the winds of the same latitudes1 deflected from a northward to a ,,ne4 course1 which carries it away from the ,american coast1 to impart some of its warmth1 7probably mainly through the winds that blow over it71 to ,great ,britain and ,ireland1 ,scandinavia1 and ,western ,europe generally2 while the northern ,american coast is left to be bathed by the icy polar current flowing from the ,arctic through ,baffin's ,bay1 which carries icebergs far to the south in the way of the transatlantic traffic between the ,eastern ,states and ,europe1 and causes a difference in climate that is well exemplified in the comparison of the climate of ,new ,york with that of ,naples1 both lying in the same latitude2 and similarly of the bleak coast of ,labrador with that of ,great ,britain4 ,the ,japan ,stream4--,on the eastern ,asiatic ,coast1 a warm current originating in the ,sunda seas1 flows off the coasts of the ,philippines and of ,china and bathes the ,japanese islands2 hence it is known as the ,japanese ,current1 or ,kuro-siro4 ,it is partly this current which1 failing to pass into the ,arctic through the shallow waters of ,behring strait1 renders the coast climates of the northwest coast of ,america so much milder and moister than is that in corresponding latitudes on the east coasts of both continents4 ,alaska corresponds to ,norway in its moist1 foggy and relatively mild coast climate2 ,british ,columbia1 ,washington and ,oregon participate in the benefits of the tempering influence of the return current of the ,kuro-siro4 ,but as this return 78,alaska07 current passes southward into the warmer seas off the ,california coast1 its influence is reversed2 it becomes a cold current in the warm waters of the ,pacific1 and the warm1 moist air of the ocean being carried by the westerly winds across this cold stream which flows along the shore of ,california1 in summer dense fogs are formed1 which render navigation difficult and produce a coast climate whose average summer and winter temperatures 7e4 g4 at ,san ,francisco7 may differ by only a few degrees1 viz41 #ae4e and #ac4j ,c4 7#fj and #ef ,f472 so that a change of clothing from season to season is hardly called for4 ,the ,alaska ,current leaves the immediate coast of ,california off ,pt4 ,conception near ,santa ,barbara1 gradually losing itself southwestward1 but still tempering the tropical heat in the ,hawaiian ,islands4 ,hence the coast climate is much warmer and less foggy in southern ,california2 but throughout the ,state in the interior valleys1 screened from the coast winds by the ,coast ranges1 the temperature in summer may rise several degrees above #ajj ,f4 for days together2 although1 owing to the dryness of the air1 the heat is not oppressive4 ,contrasting ,climates in ,n4 ,w4 ,america4--,an even more striking contrast1 showing the effects of the warm ocean and air currents1 when intercepted by mountain chains1 exists on the ,pacific coast farther northward1 as already mentioned4 ,in ,oregon and ,washington first the low ,coast ranges1 and then the higher ,cascade mountains1 obstruct the eastward progress of the westerly ocean winds4 ,the result is a very heavy rainfall to coastward of and within the ,coast ranges1 and an almost equally heavy precipitation on the western slope of the ,cascades4 ,standing on the crest of the latter in summer1 one may see to westward a rolling sea of clouds1 causing almost daily rains2 while to eastward the eye ranges over brown or whitish1 dusty plains or rolling lands1 almost destitute of tree growth and quivering with heat1 under a deep blue sky untroubled by clouds for months4 ,a somewhat similar contrast is seen in the ,hawaiian islands1 which are in the sweep of the subtropical northeast trade winds1 and on their windward 7eastern7 slopes have abundant rains2 while on the leeward slopes an almost arid climate prevails1 calling for extended irrigation4 ,continental1 ,coast and ,insular ,climates4--,from what has been said above1 the striking differences of climate caused by the position of any region with reference to the sea or other large bodies of water on the one hand1 and to mountain chains on the other1 can be readily understood2 provided of course that the direction of the winds and the trend of the mountain chains be properly taken into consideration4 ,western coasts in the temperate and subtropical regions will have a relatively even1 temperate and moist climate as compared with the interior of continents1 from which the tempering influence of the sea is cut off by mountain chains4 ,where no such chains intervene the coast climate may extend far inland4 ,the latter case is that of ,europe1 where the prevailing westerly winds1 warmed by the ,gulf ,stream1 temper the climate as far east as the borders of ,russia1 and northward to ,norway2 while to southward the warm waters of the ,mediterranean and ,black seas temper both heat and cold in ,spain1 southern ,france1 ,italy and the ,mediterranean border generally4 ,but to eastward1 in ,russia and ,siberia1 the climate becomes 8continental0 to an extreme degree1 with very cold winters and very hot summers4 ,the same is true of interior ,north ,america1 wherever the continental divide cuts off the tempering influence of the westerly winds2 ,montana1 the ,dakotas and the ,great ,plains states generally being examples4 ,the climate of the ,mississippi valley1 as stated before1 is tempered by the winds blowing from the ,gulf of ,mexico1 but with occasional irruptions of the continental climate 7sometimes reaching as far east as the ,south ,atlantic coast7 in the forms of cold 8blizzards10 from which the coast climates of the ,pacific and of western ,europe are practically free4 ,the ,atlantic coast of ,north ,america 7including the coast of the ,gulf of ,mexico71 moreover1 not unfrequently suffers from the violent cyclonic storms that originate in the ,antilles and follow more or less the direction of the ,gulf ,stream4 ,islands1 differing from continents mainly in their extent1 and having a relatively large proportion of coast1 naturally have climates controlled essentially by the surrounding ocean4 ,the insular or oceanic climates are therefore1 as a rule1 more temperate and even than are those of the nearest mainland4 ,it is often said that the climate of western ,europe is 8insular02 and owing to its position under the lee of the ,gulf ,stream1 this is eminently true of ,great ,britain4 ,subtropic ,arid ,belts4--,where the surface features of the land in relation to the ocean and prevailing winds do not interpose special obstacles1 we find to poleward of both tropics a climatic belt of greater or less width1 in which the annual1 or at least the summer rainfall is too small to maintain annual herbaceous vegetation throughout the season1 even when the temperature is favorable4 ,these two 8arid0 belts are best defined in ,africa1 where the northern one is represented by the ,sahara desert1 lower ,egypt and ,arabia1 while the southern one is exemplified in the ,kalahari desert1 to northward of the ,cape of ,good ,hope4 ,the northern belt is continued into ,asia ,minor1 ,palestine1 ,syria and ,persia1 and is again manifest in northwestern ,india2 but to eastward is stopped by the influence of the great ,himalaya range4 ,the plateau countries beyond1 in ,central ,asia1 are extremely arid1 largely by reason of their high elevation4 ,in ,australia the southern arid belt is very strongly defined4 ,in ,north ,america1 the arid belt is characteristically defined on the ,pacific ,coast4 ,it embraces all but the southernmost point of the peninsula of ,lower ,california1 with about two-thirds of the ,state of ,california2 thence eastward across ,sonora and ,arizona to ,new ,mexico and western ,texas4 ,but here the influence of the mountain ranges and high plateaus obscures the subtropical belt as such1 the arid climate continuing1 east of the great ,pacific ranges1 through ,nevada1 ,utah1 ,wyoming1 ,montana1 ,idaho1 and eastern ,oregon and ,washington nearly to the line of ,british ,columbia on the north1 and with gradually decreasing aridity1 into ,colorado1 ,kansas1 ,nebraska1 and the ,dakotas4 ,in ,south ,america the rainless seaward slopes of southern ,peru and northern ,chile indicate the southern arid belt2 but here1 the great chain of the ,andes intervening1 the dry pampas of ,argentina1 and the ,gran ,chaco of southwestern ,brazil1 like the ,nevada basin1 though arid would naturally be referred to the moisture-condensing influence of the ,andes chain1 under the lee of which they lie4 ,from this cause the region of deficient rainfall1 which on the western coast ends to northward of ,santiago de ,chile1 is east of the ,andes continued much farther poleward1 as in ,north ,america2 reaching into ,patagonia4 ,utilization of the ,arid ,belts4--,while1 as already explained1 the distribution of the rainfall through the year is nearly as important as its total amount1 yet it is evident that even with the minimum of twenty inches of total precipitation as the measure for crop production1 a very large proportion of the land of the arid region cannot1 even with the most elaborate system of water conservation1 be supplied with sufficient water for ordinary crops1 and must be otherwise utilized1 mainly for pasture purposes4 ,this is rendered practicable to a much greater extent than might be expected1 because the rapid transition from the rainy to the permanent dry season cures the standing herbage into hay1 which affords good grazing during the rainless season4 ,moreover1 the use of drought-resistant1 browsing forage plants1 both shrubs and trees1 serves to supplement materially any deficiency in the supply of 8standing hay10 especially in case the rains should toward the end be unduly delayed4 ,the same is true of the dried pods and seeds of native herbage1 which in some cases 7bur clover1 lupins1 etc417 afford highly nutritious additions to the leafy forage4#ajd #ajd ,see ,rept4 of the ,u4 ,s4 ,commissioner of ,agriculture for #ahgh1 pp4 #dhf-dhh2 ,bull4 ,nos4 #af and #db1 ,wyoming ,expt4 ,station2 ,bull4 ,no4 #aej ,calif4 ,expt4 ,station2 ,bull4 ,no4 #ea1 ,nevada ,expt4 ,station2 ,south ,dakota ,station ,bulletins ,nos4 #dj1 #fi1 #gj1 #gd2 ,kansas ,expt4 ,station1 ,bulletin ,no4 #ajb2 ,new ,mexico ,expt4 ,station1 ,bulletin ,no4 #ah2 ,montana ,expt4 ,station1 ,bulletin ,no4 #cj2 and others4 ,,chapter ,,xvii4 ,,relations ,,of ,,soils ,,and ,,plant ,,growth ,,to ,,heat4 ,the ,temperature of ,soils4--,the rapid germination of seeds1 as well as the development of plants to maturity1 is essentially dependent upon the maintenance of the appropriate temperature4 ,the temperature most favorable to germination or growth1 as well as the degree of tolerance of high and low temperatures1 varies greatly with different plants1 governing mainly what is known as their climatic adaptation4 ,a knowledge of these points with reference to the several crops is therefore of no mean importance to the farmer2 for1 to a certain extent1 he can control the temperature in the soil itself1 and he can mostly choose for sowing and planting1 the time when the soil shall have the proper temperature for rapid germination or maturity4 ,as a rule1 it is not desirable to have either seeds or seedling plants in the ground for any length of time when the temperature is too low for active vegetation2 for while they rest1 other1 lower organisms 7fungi and bacteria71 adapted to low temperatures1 may continue in full activity at the expense of the vitality of the crop plant4 ,water exerts controlling ,influence4--,since the capacity of water for heat is approximately five times greater than that of the average soil1 equal weights being considered1 it follows that the temperature of soil-water must exert a controlling influence over that of the soil4 ,taking the case of a cubic foot of loamy soil1 fully saturated with water1 in which one-third of the volume may be assumed to be water3 the weight of the dry soil being about eighty pounds per cubic foot1 calculation shows that the amount of heat required to raise the temperature of the water contained1 one degree1 will be fully twice as great as for that required for the soil itself4 ,it is thus obvious that the control of soil-temperature is largely dependent upon the control of the water-content of the same1 which has been discussed in a former chapter4 ,even in the condition of moisture known to be most favorable to plants1 viz41 one-half of the maximum water capacity1 the influence of the water-content upon the temperature will still be as great as that of the entire soil mass4 ,this consideration emphasizes the importance of such control4 ,cold and ,warm ,rains4--,it is not surprising then that the occurrence of cold or warm rains or the use of cold or warm irrigation water at critical periods1 may largely determine the success or failure of the crop4 ,it is well known that the occurrence of a cold rain after vegetation has started actively in early spring1 may not only destroy the season's fruit crop by preventing the setting1 or thereafter causing the dropping1 of the fruit1 but may even1 if the suppression of vegetative action be continued for some length of time1 result in serious injury to1 or death of trees4 ,widely extended disastrous experience of the kind was had in ,california in ,february and ,march1 #ahhg1 resulting in the death of tens of thousands of fruit trees and vines during that and the following season4 ,it is obvious that in such a case as this the rapid draining-off of the cold water through underdrains would have materially mitigated1 if not wholly prevented1 such injury4 ,solar ,radiation4--,aside1 however1 from such overwhelming influences as the above1 the soil temperatures are measurably controlled by the extent to which they receive and absorb the sun's heat rays1 whether directly or through the mediation of the air4 ,the direct effect of the sun's rays upon the surface is1 upon the whole1 the most generally potent1 although warm winds may occasionally exert a very strong influence4 ,the varying influence of the sun's rays depends primarily upon the change of seasons1 which themselves result from the varying angles at which the sun's rays strike the surface2 as well as upon the duration of the day4 ,the greater or less cloudiness or fogginess of the sky1 of course1 exerts a decided effect in this connection4 ,the ,penetration of the ,sun's ,heat into the ,soil4--,in the temperate regions of the earth the daily variations of temperature cease to be felt at depths ranging from two to three feet1 according to the nature of the soil material and its more or less compacted condition4 ,the monthly variations1 of course1 reach to greater depths2 while the annual variations do not disappear in the temperate zone1 e4 g41 at ,paris1 ,zrich and ,brussels1 at a less depth than seventy-five feet4 ,at these depths of constant temperature we find approximately the same temperature as that which we can deduce from the thermometric observations as the annual mean4 ,from similar causes the mean annual temperature of any place may be approximately deduced from the observation of the water of wells and springs derived from moderate depths4 ,for below the level of constant annual temperature the latter begins to ascend steadily as we progress downward1 owing to the interior heat of the earth4 ,change of ,temperature with ,depth4--,the following table of observations made at ,brussels illustrates the decrease of annual range of temperature with depth3 ,average ,annual ,at feet3 temperature4 range4 7,c47 7,c47 #c4be #g4b #aj4e #ae4f #ac4e #d4e #cj4h #af4d #a4c #ge4j #ag4j #j4j ,it is interesting to compare with this record that of a well sunk by ,ermann at ,yakutzk1 ,siberia1 where the mean annual temperature is--#i4g ,c4 7#ad4f ,f474 ,this temperature was found a few feet below the surface4 ,at #ej feet the temperature was--#g4b ,c4 7#ai ,f472 at #ade feet--#e ,cent4 7#bc ,f47 at #cej feet--4#i ,c4 7#cj4h ,f47 showing that the ground was below the temperature of freezing water for some distance farther down2 so that the search for liquid water was abandoned4 ,we thus see that in the ,arctic regions1 owing to the presence of water in the form of ice1 the melting of which impedes the access of solar heat1 the level of no variation is found at the distance of a few feet below the surface1 despite the great variations in temperature between the short but hot summer and the extremely cold winter4 ,in the tropics1 also1 the annual temperature-variation disappears at a less depth than #b feet1 in consequence of the very slight difference between the two seasonal extremes of temperature4 ,surface--,conditions that influence ,soil-,temperature4 ,among these1 color has already been mentioned1 and to a certain extent discussed4 ,while it is true that1 broadly speaking1 dark-colored soils absorb more of the sun's heat than light-colored ones1 other things being equal1 it must still be understood1 that the nature of the color-giving substance exerts a very material influence upon the amount of heat absorbed4 ,thus charcoal is among all known substances the one absorbing and radiating the sun's heat rays most powerfully1 and all kinds alike2 so much so1 that its absorbent power is taken as #ajj4 ,but other substances which to the eye appear equally black1 have by no means the same absorbing power4 ,the heat absorption by black humus is high1 though not quite equal to that of charcoal2 and many gray soils1 though appearing to the eye of rather light tint1 really absorb more heat than others which1 to our perception1 have the darker tint1 but are colored by other substances4 ,gardeners and especially vine growers in the colder portions of ,europe often take advantage of the powerful absorbing power of carbon by spreading charcoal or black slate powder over the surface of the soil where early maturity is specially desired2 and slate powder is similarly used by the peasants at ,chamouni to hasten the melting of the snow4 ,heat of ,high and ,low ,intensity4--,it must also be kept in view that the surfaces1 and especially the colors that favor absorption of the intense rays of the sun1 may comport themselves quite differently toward heat rays of low intensity1 such as those thrown back from the soil at night when it cools4 ,were this otherwise1 a soil that absorbs much heat in the daytime would lose it with corresponding rapidity at night4 ,but this is true only of charcoal2 in the case of most other substances1 there is a material difference in favor of the retention of the heat1 of low intensity1 by slower radiation into a 8heat-trapping0 atmosphere4 ,reflection vs4 ,dispersion of ,heat4--,theoretically1 a smooth surface reflects more heat than a rough one1 and warms much more slowly by absorption2 as is strikingly shown by the use of polished metal screens placed on walls to prevent their being overheated by a flue near by4 ,in the case of soils1 also1 the condition of the surface affects materially the absorption of heat1 but not in accordance with the above rule so far as the result is concerned4 ,for it is found that1 other things being equal1 a loose or cloddy surface disperses in many directions the heat it receives1 and does not permit it to penetrate by conduction to so great extent as would a more compact soil1 whose smooth surface would waste less of the heat received by radiation4 ,king has called special attention to the difference of temperature existing between soils smoothed and compacted by a roller1 and the unrolled soil having a loose surface4 ,he found that the former at a depth of one and a half inches was as much as #e4e;,c4 7#aj;,f47 warmer than the loose soil1 and that even at a depth of three inches a difference as high as #c4e;,c4 7#f4e;,f47 existed between the two4 ,he observed at the same time that the temperature of the air over the unrolled ground was considerably warmer than above the rolled1 thus corroborating the differences observed in the soil itself4 ,but at night the heat is given out more rapidly from the rolled than from the unrolled surface1 the latter acting as a non-conductor and keeping the soil warmer than that of the more compact rolled land4 ,king gives as the average difference observed between rolled and unrolled land on eight ,wisconsin farms1 #a4f;,c4 7#c;,f47 in favor of the rolled land between #a and #d p4m4 ,it will thus be seen that the loose tilled layer1 while impeding the penetration of the sun's heat into the deeper portions of the soil during the day1 on the other hand serves to retain it at night better than a more compact soil4 ,this obviously places it within the power of the farmer to exert considerable control over the soil-temperature at critical times2 restraining or favoring the access of the sun's heat in accordance with the requirements of the climate or season1 as the case may be4 ,influence of a ,covering of ,vegetation1 and of ,mulches4--,a cover of either living or dead vegetation depresses the temperature of the soil as compared with the bare land1 as elaborately shown by ,wollny and ,ebermeyer4 ,in the monthly averages these differences rarely exceed 4#h ,c4 7#a4e degrees ,f471 and are mostly below 4#ej ,c4 7#a ,f471 but during different parts of the day they may rise to #b4b to #b4e ,c4 7#d to #d4e ,f471 at #d inches depth4 ,in summer they are greater than at other seasons4 ,of course the density of the vegetation or the thickness of the mulch influences them materially4 ,forests exert the greatest cooling influence upon the soil1 and next to these the dense herbaceous crops1 such as clover1 and the legumes generally4 ,influence of the ,nature of the ,soil-,material4--,aside from the surface condition1 the nature of the material itself exerts a certain influence1 not only upon the rate of introduction of heat1 but also upon the amount taken up4 ,thus quartz sand having the highest density 7greatest weight per cubic foot7 and also the highest capacity for heat among the usual mineral soil-ingredients1 will1 mass for mass1 experience a smaller rise of temperature than would clay or loam soil1 of less density or volume-weight1 and also of lower heat-capacity4 ,while this holds good theoretically1 differences corresponding to this consideration rarely occur in nature1 for the reason that the much greater influence of the mechanical condition of the soil mostly overbalances these effects4 ,thus ,wollny has shown that while quartz is a better heat-conductor than clay1 quartz cobbles or gravel will materially increase the temperature of the soil in which they are imbedded4 ,yet compact clay is a better conductor of heat than loose sand2 hence the latter1 when exposed to the intense heat of the summer sun in the desert1 becomes intensely hot on the surface1 yet allows of the existence of abundant moisture at a depth of ten or twelve inches2 while clay in the same region1 being usually in a compacted condition1 will show a lower surface-temperature and will be warmer and drier at a depth at which sand will still retain abundant moisture1 and be comparatively cool 7,see chap4 #ac1 p4 #beg47 ,so much indeed depends upon the state of mechanical division and flocculation in which the several soils may happen to be1 that a hard-and-fast statement in regard to their relations to heat cannot and should not be given1 as it would only lead to disappointments and practical mistakes2 the more as in all cases the moisture-condition exerts an influence predominating by far over that of the dry material itself1 and this moisture-condition is subject to rapid changes1 owing to intrinsic differences in the several classes of soils4 ,wollny states as the result of his experiments1 that in summer sandy soils are warmest2 then humous1 lime and loam soils2 while in winter humous soils are warmest1 then loams2 and sand coldest4 ,influence of ,evaporation4--,in treating of the ,conservation of ,soil ,moisture 7chapter #ac71 the effects1 conditions and control of evaporation from the soil have already been discussed from several points of view2 so that a summary review of the subject must suffice in this place4 ,it has been stated above that in the case of an average loam soil saturated with water1 the heat required to raise the temperature of the water one degree would be about twice that needed to so change the dry soil material itself4 ,but if it is required to evaporate the same amount of water from the soil1 nearly ten 7#i4ffg7 times that amount of heat will be required2 or in the case assumed1 twenty times as much as would suffice to raise the temperature of the dry soil through an equal interval of temperature4 ,while in a few cases the cooling of the soil by evaporation is desirable1 in the vast majority of cases it is injurious to the progress of vegetation1 and should be restricted as much as possible by the means outlined in a former chapter4 ,formation of ,dew4--,there is1 however1 another aspect of evaporation from the soil which has been long misunderstood1 although the true state of the case was partially recognized long ago4 ,dew is in common parlance said to 8fall10 it being supposed that1 like rain1 it is derived from the atmosphere4 ,while this is partially true1 inasmuch as from very moist1 and notably from foggy air dew is frequently deposited on grass and foliage generally1 as well as on wood and other strongly heat-radiating surfaces2 yet as a matter of fact1 in by far the majority of cases1 as shown by ,h4 ,e4 ,stockbridge#aje and confirmed by everyday observation1 dew is formed from the vapor rising from the warmer soil into a colder atmosphere1 and condensed on the most strongly heat-radiating surfaces near the ground1 such as grass1 leaves both green and dry1 wood1 and other objects first encountering the rising vapor4 ,in manifest proof of this it will be noted that very heavy dews may be seen on the ground1 when the roofs of houses as well as the higher shrubs and trees remain perfectly dry4 ,in winter this may be most strikingly seen in the deposition of hoar-frost in and immediately around the cracks of plank sidewalks1 whose surface remains dry4 #aje 8,rocks and ,soils10 pp4 #age-ahi4 ,dew rarely adds ,moisture4--,candid observations will convince any one1 therefore1 that in most cases the supposed addition to the moisture of the soil from dews is an illusion4 ,whatever dewdrops fall on the ground are in general simply the return to the soil of a part of what came from it2 while the dew that evaporates from the bedewed leaves or other objects represents simply a delayed outgo of moisture from the soil1 which for a time retards evaporation direct from the soil1 and thus effects a slight saving of moisture4 ,but while this is measurably true of inland and especially of continental areas like the great plains of ,north and ,south ,america1 it is also true that in deep moist valleys1 and on the rainy and foggy coast regions of continents1 dews are found to both fall and rise1 not uncommonly to such an extent as to be equivalent to a not inconsiderable aggregate precipitation4 ,thus in the moist coast belt of ,oregon and ,washington lying west of the ,cascade range of mountains1 the morning dews of summer are frequently so copious that the water falls in showers from the lower trees and shrubs1 so as to necessitate the use of water-proof clothing when traversing the woods in the morning1 quite as much as though rain was actually falling4 ,in hilly and more especially in mountainous regions the cold air descending from above and flowing down in the ravines will often cause a heavy condensation of dew in these1 while the bordering ridges1 which rise above the cold currents1 remain free from dew4 ,these descending currents as a rule not only bring no surplus moisture with them1 but in their downward course become warmer by contraction and therefore relatively drier4 ,in these cases also1 therefore1 the dew is purely moisture derived from the ground1 which in rising encounters the cold air and is thus condensed4 ,the fact that dew is most commonly derived from the soil could have been foreseen from the other fact1 long ascertained and known1 that during the night the soil is as a rule warmer than the air above it2 as has been shown by the earlier observers1 as well as more specifically by ,stockbridge4 ,dew within the ,soil4--,it is obvious that whenever dew is formed above the surface of the soil1 the air within the latter must be at or near its point of saturation with vapor1 as in fact is usually the case a few inches below the surface4 ,it follows that when a depression of temperature occurs within the soil1 e4 g41 at night1 dew must be deposited within the soil down to the depth to which the nightly variation reaches1 increasing at that depth as the vapor from the warmer soil below rises1 to be in its turn condensed4 ,there is thus formed at that level a zone of greater moisture1 which may sometimes be noted in digging pits1 by a deeper tint1 without any corresponding variation in the nature of the soil4 ,the daily repetition of this process1 at varying depths1 and its greater or less recurrence at or near the limit-levels of monthly and even annual variations1 must exert a not inconsiderable influence upon the vertical distribution of moisture in the soil2 which instead of being usually found in horizontal bands or zones of varying moisture-contents1 is usually remarkably uniform for considerable depths1 despite the fitfully recurrent additions from rains4 ,it is at least probable that this process of dew-formation within the soil materially assists capillarity in effecting a measurably uniform vertical distribution of moisture4 7,see also page #bjg1 chapter #aa74 ,plant-development under different ,temperature ,conditions4--,in the arctic regions the ground1 frozen in winter to unknown depths1 may thaw to only three to five feet during the summer1 notwithstanding the great length and continuous sunshine of the arctic day4 ,the shallow-rooted arctic flora develops very rapidly under the influence of the continuous daylight and heat1 in the course of from five to eight weeks4 ,the seeds of these plants must1 of course1 be capable of germinating at very low temperatures2 and as a matter of fact1 we find that both in the arctic regions and in the higher mountains1 certain plants are found growing and blooming on slopes flecked with snow2 each plant surrounded by a small circle of bare ground1 where the snow has been melted under the influence of the dark-tinted earth and leaves4 ,it is clear that here germination has occurred1 the foliage has been formed1 and the roots have been exercising their vegetable functions1 in ground soaked with water practically ice-cold4 ,germination of ,seeds4--,while wild plants of special adaptation may thrive in very low 7or high7 temperatures1 it is also true that few of our cultivated plants will germinate1 and still less grow thriftily1 at such low temperatures4 ,the limit below which most cultivated plants may be considered as remaining practically inactive lies between #d4d and #g4b ,c4 7#dj and #de ,f474 ,few tropical plants will germinate much below #bc4h 7#ge ,f47 and in some cases not below #ce ,cent4 7#ie ,f474 ,even maize and pumpkins1 according to ,haberlandt1 germinate most rapidly between #ce and #ch4c ,c4 7#ie and #aja ,f471 while for wheat1 rye1 oats and flax the best temperature for germination lies between #ba4a to #bf4a 7#gj to #gi74 ,under the most favorable conditions of temperature and moisture1 some small seeds which readily absorb moisture will germinate in from twenty-four to forty-eight hours1 while at a lower temperature they may require from three days to two weeks4 ,thus ,haberlandt found that while oats would germinate in two days at a temperature of #ag4b to #ag4e ,c4 7#fc to #fc4e71 it took a full week for germination when the temperature was only #e ,c4 7#da ,f474 ,it is obvious that seeds remaining inert in the soil for such lengths of time will be subject to a variety of vicissitudes that may injure or destroy their vitality4 ,there are many bacteria and fungous parasites which at low temperatures are perfectly capable of attacking and destroying the water-soaked seed4 ,there is thus for each plant1 from the lowest to the highest1 a certain temperature most favorable to development2 and both above and below this1 the vegetative activity is seriously interfered with or wholly checked4 ,a knowledge of these limits is manifestly of the utmost practical importance4 ,the influence of too high a temperature in preventing the germination of cinchona seed from ,india1 was curiously exemplified when it was subjected to a supposedly favorable steady temperature of #bc4h ,c4 7#ge ,f47 under otherwise most favorable conditions4 ,not a single one came up in the course of six weeks1 and the box in which it had been sown was put away outside of the hothouse as a failure4 ,within two weeks a full stand of seedlings was obtained1 at temperatures ranging between #ab4g and #ae4e ,c4 7#ee and #fj ,f474 ,the fact that the cinchona is a tree of the lower slopes of the ,andes 7three to five thousand feet7 although at home strictly within the tropics1 explains the apparent anomaly4 ,,part ,,third4 ,,chemistry ,,of ,,soils4 ,,chapter ,,xviii4 ,,the ,,physico-,,chemical ,,investigation ,,of ,,soils ,,in ,,relation ,,to ,,crop ,,production4 ,the chemical constituents of soils have been incidentally mentioned and discussed above1 both in connection with the processes of soil-formation1 and with the minerals that mainly participate therein4 ,the manner of their occurrence and their relations to plant life1 so far as known1 must now be considered more in detail4 ,,historical ,,review ,,of ,,soil ,,investigation4 ,while the obvious importance of the physical soil-conditions has long ago rendered them subjects of close study by ,schbler#ajf ,boussingault and others1 the chemistry of soils was very generally neglected for a considerable period1 after the hopes at first entertained by ,liebig that chemical analysis would furnish a direct indication and measure of soil fertility1 had been sorely disappointed in respect to the only soils then investigated1 viz41 the long-cultivated ones of ,europe4 ,the results of chemical analysis sometimes agreed1 but as often pointedly disagreed1 with cultural experiences2 so that after the middle of the nineteenth century1 but few thought it worth while to occupy their time in chemical soil analysis4 #ajf ,the early work of ,schbler on soil physics1 published at ,leipzig in #ahch under the title of 8,grundstze der ,agrikulturchemie0 and now almost inaccessible outside of old libraries1 is remarkable as having anticipated very definitely much that has since been brought forward and elaborated anew4 ,he is really the father of agricultural physics4 ,popular ,forecasts of ,soil ,values4--,in newly-settled countries1 and still more in those yet to be settled1 the questions of the immediate productive capacity1 and the future durability of the virgin land are the burning ones1 since they determine the future of thousands for weal or woe4 ,this need has long ago led to approximate estimates made on the part of the settler1 by the observation of the native growth1 especially the tree growth2 and where this consists of familiar species1 normally developed1 such estimates on the part of experienced men1 based on previous cultural experience1 are generally very accurate2 so much so that in many of the newer states they have been adopted in determining not only the market value1 but also the tax rate upon such lands1 their productiveness1 and probable durability being a matter of common note4 ,thus in the long-leaf pine uplands of the ,cotton ,states1 the scattered settlements have fully demonstrated that after two or three years cropping with corn1 ranging from as much as #be bushels per acre the first year to ten and less the third1 fertilization is absolutely necessary to farther paying cultivation4 ,should the short-leaved pine mingle with the long-leaved1 production may hold out for from five to seven years4 ,if oaks and hickory are superadded1 as many as twelve years of good production without fertilization may be looked for by the farmer2 and should the long-leaved pine disappear altogether1 the mingled growth of oaks and short-leaved pine will encourage him to hope for from twelve to fifteen years of fair production without fertilization4 ,corresponding estimates based upon the tree growth and in part also upon minor vegetation1 are current in the richer lands also4 ,the 8black-oak and hickory uplands10 the 8post-oak flats10 8hickory bottoms10 8gum bottoms10 8hackberry hammocks10 8post-oak prairie10 8red-cedar prairie10 and scores of other similar designations1 possess a very definite meaning in the minds of farmers and are constantly used as a trustworthy basis for bargain and sale1 and for crop estimates4 ,moreover1 experienced men will even after many years' cultivation be able to distinguish these various kinds of lands from one another4 ,cogency of ,conclusions based upon ,native ,growth4--,since the native vegetation normally represents the results of secular or even millennial adaptation of plants to climatic and soil-conditions1 this use of the native flora seems eminently rational4 ,moreover1 it is obvious that if we were able to interpret correctly the meaning of such vegetation with respect not only to cultural conditions and crops1 but also as regards the exact physical and chemical nature of the soil1 so as to recognize the causes of the observed vegetative preferences2 we should be enabled to project that recognition into those cases where native vegetation is not present to serve as a guide2 and we might thus render the physical and chemical examination of soils as useful practically1 everywhere1 as is1 locally1 the observation of the native growths4 ,to a certain extent1 such knowledge would be useful in determining the salient characters of cultivated soils1 also2 and would be the more useful and definite in its practical indications the more nearly the cultural history of the land is known1 and the less the latter has been changed by fertilization4 ,for1 so soon as the first flush of production has passed1 the question of how to fertilize most effectually and cheaply demands solution4 ,it was from this standpoint1 suggested by his early experience in the ,middle ,west and subsequently most impressively presented to him in the prosecution of the geological and agricultural survey of ,mississippi1 that the writer originally undertook1 in #aheg1 the detailed study of the physical characters and chemical composition of soils4 ,it seemed to him incredible that the well-defined and practically so important distinctions based on natural vegetation1 everywhere recognized and continually acted upon by farmers and settlers1 should not be traceable to definite physical and chemical differences in the respective lands1 by competent1 comprehensively-trained scientific observers1 whose field of vision should be broad enough to embrace concurrently the several points of view--geological1 physical1 chemical and botanical--that must be conjointly considered in forming one's judgment of land4 ,such trained observers should not merely do as well as the 8untutored farmer10 but a great deal better4 8,ecological0 studies4--,yet thus far we vainly seek in general agricultural literature for any systematic or consistent studies of these relations4 ,we do find 8ecological0 lists of trees and other plants1 or 8plant associations10 growing in certain regions or land areas1 described in some of the general terms which may refer equally well to lands of profuse productiveness1 or to such as will hardly pay for taxes when cultivated4 ,or when the productive value is mentioned1 the probable cause of such value is barely alluded to1 even conjecturally1 unless it be in describing the 8plant formations0 as xerophytic1 mesophytic or hydrophytic1 upon the arbitrary assumption that moisture is the only governing factor2 wholly ignoring such vitally important factors as the physical texture of the soil1 its depth1 the nature of the substrata1 and the 7oftentimes abundantly obvious7 predominant chemical nature of the land4 ,and on the other hand1 we find even public surveys proceeding upon the basis of physical data alone1 practically ignoring the botanical and chemical point of view1 and inferentially denying1 or at least ignoring1 their relevancy to the practical problems of the farm4#ajg #ajg ,bull4 #bb1 ,bureau of ,soils1 ,u4 ,s4 ,dept4 of ,agriculture4 ,early ,soil ,surveys of ,kentucky1 ,arkansas and ,mississippi4--,among the few who during the middle of the past century maintained their belief in the possibility of practically useful results from direct soil investigation1 were ,drs4 ,david ,dale ,owen and ,robert ,peter1 who prosecuted such work extensively in connection with the geological and agricultural surveys of ,kentucky and ,arkansas2 and the writer1 who carried out similar work in the states of ,mississippi and ,louisiana1 with results in many respects so definite that he has ever since regarded this as a most fruitful study1 and has later continued it in ,california and the ,pacific ,northwest4 ,this was done in the face of almost uniform discouragement from agricultural chemists until within the last two decades2 with occasional severe criticisms of this work as a waste of labor and of public funds4 ,investigation of ,cultivated ,soils4--,all this opposition was largely due to the prejudices engendered by the futile attempts to deduce practically useful results from the chemical analysis of soils long cultivated1 without first studying the less complex phenomena of virgin soils2 and these prejudices persisted longest in the ,united ,states1 even though in ,europe the reaction against the hasty rejection of chemical soil work had begun some time before2 as is evidenced by the methods employed at the ,rothamsted ,experimental ,farm in ,england1 the ,agricultural ,college of ,france1 the ,russian agronomic surveys1 and at several points in ,germany4 ,in none of these cases1 however1 more than the purely chemical or physico-chemical standpoint was assumed2 although in ,russia at least1 virgin soils were easily obtainable and their native growth verifiable2 and were actually in part made the subject of chemical investigation4 ,in the course of their work1 ,owen and ,peter always carefully recorded the native vegetation of the soils collected2 but neither seems to have formulated definitely the idea that such vegetation might be made the basis of direct correlation of soil-composition with cultural experience4 ,owen repeatedly expressed to the writer his conviction that such a correlation could be definitely established by close study2 but early death prevented his personal elaboration of the results of his work4 ,peter likewise stoutly maintained to the last his conviction that soil analysis was the key to the forecasting of cultural possibilities2 but not being a botanist he did not see his way to put such forecasts into definite form4 ,change of ,views4 ,in the ,united ,states as well1 the ancient prejudices have now gradually given way before the urgent call for more definite information than could otherwise possibly be given to farmers by the experiment stations1 most of whose cultural experiments1 made without any definite knowledge of the nature of the soil under trial1 were found to be of little value outside of their own experimental fields4 ,even the multiplication of culture stations in several states1 unaccompanied by soil research1 is found to be a delusive repetition of the same inconclusive1 random experimenting1 since it takes into consideration only the climatic differences1 but leaves out of consideration the potent factors of soil quality and soil variations4 ,at most these were usually mentioned by them in such indefinite terms as 8a clay loam10 8a coarse sandy soil10 8gray sediment land10 and the like2 frequently not even with a statement of the depth and character of the subsoil and substrata1 much less of their geological derivation or correlations4 ,thus any one not happening to be personally acquainted with the land in question would be wholly without definite data to correlate the results with his own case4 ,it is quite obvious that even if only to make possible the identification of new lands with others that have already fallen under cultural experience1 and can therefore afford useful indications to the new settler1 a close physical and chemical characterization of lands should be made the special object of study by the experiment stations and public surveys1 particularly in the newer states4 ,advantages for ,soil ,study offered by ,virgin ,lands4--,among the special advantages1 then1 offered by virgin soils for the study of the correlations of soils and crops1 the usual existence of a native flora1 representing the results of secular adaptation1 is of fundamental importance4 ,as it is at this time still historically known of most lands west of the ,alleghenies what was their original timber growth1 it is clear that their original condition can still be ascertained by comparison with uncultivated lands of similar growth1 usually not very far away2 and as their cultural history also is largely within the memory of the living generation1 the behavior of such lands under cultivation is known or verifiable4 ,foremost among the data thus ascertainable is the duration of satisfactory crop production1 and its average amount4 ,to ascertain these surviving data by inquiry among the farming population should be among the foremost duties of those connected with soil surveys2 and persons temperamentally unable to enlist the farmer's sympathy and interest in such inquiries must be considered seriously handicapped1 no matter what their scientific qualifications may be4 ,in no quest is it more literally true that there is no one from whom the earnest inquirer may not learn something worth knowing4 ,practical ,utility of ,chemical ,soil-,analysis2 ,permanent ,value vs4 ,immediate ,productiveness4--,in many existing treatises so much emphasis is given to the alleged proofs of the inutility of chemical soil examination in particular1 that a special controversion of these arguments seems necessary1 in connection with a detailed statement of what can1 and in part has been1 done in that direction4 ,hence the often-repeated allusion1 in the sequel1 to points bearing on this question4 ,hence1 also1 the detailed discussion of many points which in most agricultural publications are given only passing notice4 ,in all these discussions the difference between the ascertainment of the permanent-productive value of soils1 as against that of their immediate producing capacity1 must be strictly kept in view4 ,the former interests vitally the permanent settler or farmer2 the latter concerns the immediate outlook for crop production1 the 8,dngerzustand0 of the ,germans4 ,the methods for the ascertainment of these two factors are wholly distinct1 even though the results and their causes are in most cases intimately correlated4 ,the failure to observe this distinction accounts for a great deal of the obloquy and reproach that has in the past so often been heaped upon chemical soil-analysis and its advocates4 ,,physical ,,and ,,chemical ,,conditions ,,of ,,plant ,,growth4 ,while it is true that plants cannot form their substance or develop healthy growth in the absence or scarcity of the chemical ingredients mentioned on page xxxi of this volume1 it is also true that they cannot use these unless the physical conditions of normal vegetation are first fulfilled4 ,both sets of conditions are intrinsically equally important and exacting as to their fulfilment2 and the farmers' task is to bring about this concurrence to the utmost extent possible4 ,the chemical ingredients of plant-food can1 however1 be artificially supplied in the form of fertilizers1 should they be deficient in the soil2 but as has been shown in the preceding pages1 it is not always possible to correct1 within the limits of farm economy1 physical defects existing in the land4 ,hence1 however important is the natural richness of the soil in plant-food1 the first care should always be given to the ascertainment of the proper physical conditions in the soil1 subsoil and substrata4 ,without these1 oftentimes1 no amount of cultivation1 fertilization and irrigation is effective in assuring profitable cultural results4 ,condition of the ,plant-food ,ingredients in the ,soil4--,but even the abundant presence of the plant-food ingredients1 as shown by analysis1 will not avail1 unless at least an adequate portion of the same exists in a form or forms accessible to plants4 ,of course this condition would seem to be best fulfilled by the ingredients in question being in the water-soluble condition4 ,but in the first place1 plants are quite sensitive to an over-supply of soluble mineral salts1 as is evidenced by the injurious effects produced by the latter in saline and alkali lands4 ,furthermore1 substances in that form would be very liable to be washed or leached out of the soil by heavy rains or irrigation1 and would be lost in the country drainage4 ,it is therefore clearly desirable that only a relatively small proportion of the useful soil-ingredients should be in the water-soluble or physically absorbed condition1 but that a larger supply should be present in forms not so easily soluble1 yet accessible to the solvent action which the acids of the soil and of the roots of plants are capable of exercising4 ,this virtually available supply we may designate as the reserve food-store4 ,finally1 there is practically in all soils a certain proportion of the soil-minerals in their original form1 as they existed in the rock-materials from which the soil was formed4 ,these minerals being usually in a more or less finely divided or pulverulent condition1 they are attacked much more rapidly by the chemically-acting 8weathering0 agencies1 viz41 water1 oxygen1 carbonic and humus acids1 than when in solid masses2 and thus1 transformation of the inert rock-powder into the other two classes of mineral soil-ingredients progresses in naturally fertile soils with sufficient rapidity to produce1 in a single season1 sensible and practically important results1 known as the effects of fallowing4 ,the ,reserve4--,the nature of these processes has been discussed in chapters #a to #d2 and it will be remembered that two of their most prominent results are the formation of clay1 and of zeolitic-compounds1 the latter being1 as heretofore stated 7pp4 #cf ff7 hydrous silicates of earths and alkalies1 easily decomposable by acids1 and also capable of exchanging part or the whole of such basic ingredients with solutions of others that may enter the soil4 ,these zeolitic compounds therefore fulfil two important functions in the premises1 viz43 a ready yielding-up of part of their ingredients to acid solvents1 and a tendency to fix1 by exchange1 a portion or the whole of the soluble compounds that may be set free in1 or brought upon the land4 ,the first-mentioned property is of direct avail in that the soil-humus forms1 and the roots of plants exude1 acid solvents on their surface1 and can thus draw upon the reserve store of food2 the second tells in the direction of preventing the waste of water-soluble manurial ingredients supplied to1 or formed in the soil4 7,see above1 chapter #c1 page #ch74 ,the reserve food-store may then be placed under the following heads3 ,hydrous or 8zeolitic0 silicates1 from which dilute acids can take up the bases potash1 soda1 lime and magnesia4 ,these silicates may be in either the gelatinous or powdery form2 in the former case they may also occlude water-soluble substances4 ,carbonates of lime and magnesia1 which are readily dissolved by carbonated water as well as by the vegetable acids4 ,phosphates of lime and magnesia1 not very readily soluble in carbonated water1 but more readily attacked by the acids of the soil and of plant roots2 thus supplying phosphoric acid to plants4 ,the more finely divided they are the more readily they are dissolved2 some soils containing only crystalline needles of apatite 7see chap4 #e1 p4 #fc7 only are nevertheless poor in available phosphoric acid4 ,the natural phosphates of iron and alumina are practically insoluble in all solvents at the disposal of vegetation and though present in considerable amounts in some soils1 7see chapter #ai1 page #cee71 may be considered as being permanently inert1 and therefore not to be counted among the soil resources for plant nutrition4 ,as yet no artificial process by which their phosphoric acid can be made available within the soil1 has been discovered4 ,water-soluble ,ingredients4--,as regards these it has already been explained that they are largely retained in the condition of purely physical adsorption1 as in the case of charcoal or quartz sand1 through which sea water filters and is thereby partially deprived of its salts4 ,but these can be gradually withdrawn by washing with pure water alone1 and still more easily when stronger solvents are used4 ,since the soil-water is always more or less charged with carbonic acid1 and the roots themselves secrete carbonic as well as stronger acids in their absorption of mineral plant-food1 there is no difficulty about explaining the manner in which such physically condensed ingredients are taken up4#ajh #ajh ,whitney 7,bull4 #bb1 ,u4 ,s4 ,bureau of ,soils7 claims on the basis of a large number of 7three-minute7 extractions of soils made with distilled water1 that these solutions are essentially of the same composition in all soils2 that all soils contain enough plant-food to produce crops indefinitely2 and that the differences in production are due wholly to differences in the moisture supply1 which he claims is1 aside from climate1 the only governing factor in plant growth4 ,the tables of analytical results given in ,bull4 #bb fail to sustain the first contention2 the second is pointedly contradicted both by practical experience1 and by thousands of cumulative culture experiments made by scientific observers2 the third fails with the second1 except of course in so far as an adequate supply of moisture is known to be an absolute condition both of plant growth1 and the utilization of plant-food4 ,it is moreover well known that it is not water alone1 but water impregnated more or less with humic and carbonic acids1 that is the active solvent surrounding the plant root4 ,recognition of the ,prominent ,chemical ,character of ,soils4 ,in a former chapter the soils formed from the several minerals and rocks have been discussed in a general manner4 ,we can as a rule obtain some insight into the nature of any soil which we can trace to its parent rock or rocks1 if we are acquainted with the composition of the latter4 ,similarly1 but in a much more direct manner1 we can obtain a strong presumption as to the nature of any soil by determining the undecomposed minerals present in it4 ,in all ordinary cases the presumption must be that the decomposed portion of the soil has been derived from the minerals still found in it4 ,of course it may happen in the case of lands derived from widely distinct and distant regions that no such characteristic minerals can be found2 this is very commonly true of the soils forming the deltas of large rivers1 in which sometimes the only remaining recognizable mineral is quartz in its several forms1 with occasional grains of such hardy minerals as tourmaline1 garnet1 etc4 ,apart from such cases1 the hand lens or the microscope permits us to recognize in most soils the minerals that have mainly contributed to their formation1 thus also gaining a clew to their prominent chemical nature4 ,such recognition sometimes involves1 of course1 a somewhat intimate knowledge of mineralogy2 yet a little practice will enable almost any one to identify the more important soil-forming minerals1 under the lens or microscope1 according to the degree of abrasion or decomposition they may have undergone4 ,the details of such researches lie outside of the limits of this treatise1 but some general directions on the subject are given farther on4#aji #aji ,see ,appendix ,b4 ,acidity1 ,neutrality1 ,alkalinity4--,a test never to be omitted is that of the reaction of the soil on litmus or other test paper1 to ascertain its acid1 neutral or alkaline reaction4 ,should the latter occur quickly 7by the prompt blueing of red litmus paper71 8black alkali0 would be indicated2 but a blueing after #bj to #cj minutes means merely that a sufficiency of lime carbonate is present4 ,an acid reaction 7the reddening of blue litmus paper7 of course indicates a 8sour0 soil 7see chap4 #h1 page #abb74 ,chemical ,analysis of ,soils4--,when the observations mentioned above give no very decisive results or inferences as to the soil's chemical character1 the more elaborate processes of qualitative and quantitative chemical analysis may be called in4 ,it would seem at first sight that these ought to yield very definite results to guide the cultivator2 yet such is by no means always the case4 ,both the previous history of the land1 and the method of analysis1 influence materially the practical utility of the results of chemical soil analysis4 ,the cause of this uncertainty becomes obvious when we consider the three groups of ingredients outlined above1 viz41 the insoluble or unavailable1 wholly undecomposed rock minerals2 the 8reserve10 consisting of compounds not soluble in water but soluble in or decomposable by weak acids2 and the water-soluble portion1 either actually dissolved in the water held by the soil1 or held by the soil itself in 7physical7 absorption4 ,while the latter portion is directly and immediately available to plants1 the amounts thus held are usually quite small1 and 7outside of alkali lands7 would rarely suffice for the needs of a crop during a growing season4#aaj ,this demand must be materially supplemented by what can be made available from the soil minerals and the 8reserve0 by weathering1 conjoined with the direct action of the acids secreted from the plant's root-hairs upon the soil particles to which they are attached4 ,it is obvious that the greater or less abundance of the plant-food in the soil-material upon which these processes may be brought to bear1 must essentially influence the adequacy of the plant-food thus supplied4 ,moreover1 the greater or less extent to which these sources may have been drawn upon previously in the course of cultivation1 will similarly influence that adequacy1 on account of the diminution of the readily available supply4 #aaj ,the investigations of ,king 7,on the ,influence of ,soil ,management upon the ,water ,soluble ,salts in ,soils and the ,yield of ,crops1 ,madison1 #aijc7 show that from some soils at least1 a sufficiency of plant-food ingredients for a season's crop may be dissolved by distilled water alone1 if the soil be repeatedly leached and dried at #aaj4 ,whether such a supply can be expected under field conditions1 remains to be tested4 ,water-soluble and ,acid-soluble ,portions most ,important4--,it thus seems that while the undecomposed rock minerals are indicative of the nature of the soil1 but not directly concerned in plant nutrition1 the most direct interest attaches to the water-soluble portion1 and the acid-soluble reserve4 ,both of these can1 of course1 be withdrawn from the soil by treatment with acids of greater or less strength2 and it would seem that if we knew just what is the kind and strength of the acid solvent employed by each plant1 we could so imitate their action as to determine definitely whether or not the soil contains an adequate or deficient supply of actually available food for the coming crop4 ,we ,cannot ,imitate ,plant-root ,action4--,in this1 however1 we encounter serious difficulties4 ,the acids secreted by the plant roots are not the only solvents active in the dissolution of plant-food2 as yet we know the nature of only a few2 and even these1 instead of acting for a long time 7season7 on a relatively small number of soil particles touched by the root-hairs1 can in our laboratories only be allowed to act for a short time on the entire soil-mass4 ,clearly1 the results thus obtained cannot be a direct measure of the amount of plant-food which a plant may take up in a given time2 we can only gain comparative figures4 ,these1 however1 can be utilized by comparison with actual cultural experience obtained in similar cases4 ,cultural experience must1 of course1 be the final test in all these questions2 and it is generally more fruitful to investigate the causes underlying such actual practical experience1 than to attempt to supply1 artificially1 the supposed conditions of plant growth4 ,the latter are so complex and so difficult of control1 that the results obtained by synthetic1 small-scale experiments are constantly liable to the suspicion that they are partly or wholly due to other causes than those purposely supplied by the experimenter4 ,analysis of ,cultivated ,soils4--,it is also clear that in view of the inevitable complexity of the conditions governing vegetable growth1 we should whenever feasible proceed from the more simple to the more complex4 ,the failure to conform to this rule in soil investigation has been the cause of an enormous waste of energy and work bestowed1 at the very outset1 upon the most complex problem of all1 viz41 the investigation of soils long cultivated and manured2 lands which1 having been subject perhaps for centuries to a great and wholly indefinite variety of crops and cultural practices1 had thereby become so beset with artificial conditions that without a previous knowledge of what constitutes the normal regime in natural soils1 the correlation of their chemical constitution1 as ascertainable by our present methods1 with their production under culture1 became as complex a problem as that of motions of three mutually gravitating points in space4 ,neither can be solved by the ordinary processes of analysis1 chemical or mathematical4 ,nevertheless1 though it was at one time contended that the minute proportion of plant-food ingredients withdrawn from soils by cultivation could not be detected by quantitative analysis1 numerous examples have shown that with our present more delicate methods this can in most cases be done1 though not always after a single year's crop4 ,methods of ,soil ,analysis4--,the more or less incisive solvent agents used in extracting a soil for analysis will of course produce results widely at variance with each other4 ,when fusion with carbonate of soda1 or treatment with fluohydric acid is resorted to1 we obtain for each soil-ingredient the sum of all the amounts contained in each of the three categories--the unchanged minerals1 the zeolitic 8reserve10 and the water-soluble portion4 ,it was early recognized that the results of such analyses bear no intelligible relation to the productive capacity of soils2 for pulverized rocks of many kinds1 or volcanic ashes freshly ejected and notoriously incapable of supporting plant growth1 might be made to give exactly the same composition4 ,the amounts of plant-food ingredients thus shown might be several hundreds or thousands of times greater than what one crop would take from the soil1 and yet not an ear of grain could be produced on the material4 ,the only case in which any useful information could be thus obtained would be that of the absence1 or great scarcity1 of one or more of the plant-food ingredients4 ,the next step was to use in soil analysis acids of such strength as to dissolve all the zeolitic 7and water-soluble7 portion1 leaving the unweathered soil minerals behind2 it being assumed that the prolonged action of the roots and soil-solvents would in the end act similarly to the acids employed1 such as chlorhydric or nitric acids4 ,but here also the results of analysis very commonly failed to correspond to cultural experience in the case of cultivated soils2 which frequently failed utterly to produce satisfactory crops even when the acid-analysis had shown an abundance of plant-food ingredients4 ,upon this evidence1 this method of soil investigation was also condemned as being of little or no practical utility2 and this has ever since been a widely prevalent view4 ,the preferable investigation of cultivated soils was due to the fact that they are practically the only ones available in the countries where the study of agricultural science was then being prosecuted2 and the paucity of useful results there achieved discouraged the undertaking of similar researches where1 as in the ,united ,states1 the materials for the investigation of the simpler cases--those of unchanged1 natural or virgin soils--were readily accessible4 ,it was not apparent on the surface that the indefinitely varied conditions introduced by long culture would inevitably cause this lack of definite correlation between the immediate productive capacity of a soil and the composition of its acid-soluble portion1 and that yet the same might not be true of natural1 uncultivated soils1 which have all been subjected1 alike1 only to the natural processes of weathering1 and to the annual return of nearly the whole of the ingredients withdrawn by plant growth4 ,following the failure of the treatment with strong acids to yield with cultivated soils results definitely correlated with cultural experience1 numerous attempts were made to gain better indications by the employment of weaker acid solvents4 ,the pure arbitrariness of such diluted solvents was equaled by the total indefiniteness and irrelevance of the results with different soils4 ,only two rational alternatives seem to remain1 viz41 either to push the extraction to the full extent beyond which action becomes so slow as to clearly exclude any farther effective action of plant acids2 or else to use the latter themselves at such strengths as by actual experiment is found to exist in their root sap4 ,the first alternative aims to ascertain the permanent productive values of soils2 the latter to test their immediate productive capacity4 ,both alternatives are purely empirical1 and derive their only claim to practical value from their accordance with practical experience 7see chapter #ai74 ,,the ,,solvent ,,action ,,of ,,water ,,upon ,,soils4 ,the almost universal solvent power of pure water has already been alluded to in chapter #b 7see p4 #ah71 and illustrated by the analyses of drain and river waters4 ,while these convey a general idea of the chief substances dissolved and carried off1 the direct investigation of the solutions actually obtainable from the soil by longer treatment and with no more water than is compatible with the welfare of ordinary crops1 necessarily gives somewhat different results4 ,for when drains flow during or after heavy rains the water has not time to become saturated4 ,the following data afford a clearer insight into the actual and possible solvent effects of water in the soil1 and its possible adequacy to plant nutrition unaided by acid solvents4 ,extraction of ,soils with ,pure ,water4--,eichhorn and ,wunder treated soils from ,bonn1 and from ,chemnitz 7,saxony7 respectively for ten days and four weeks with about one-third of their weight of water2 the solutions thus obtained contain in #a1jjj1jjj parts3 ,bonn4 ,chemnitz4 ---------------------------------------- ---- ,silica #dh4j #be4g ,potash 7,k,o7 #aae4d #g4e ,soda 7,na,o7 #aa4j #cj4d ,lime 7,ca,o7 #abh4j #hc4f ,magnesia 7,mg,o7 #ch4d #cg4d ,peroxid of ,iron 7,fe,o7 ,trace #aa4g ,alumina 7,al,o7 8 8 ,phosphoric acid 7,p,o7 #ca4j ,trace ,sulfuric acid 7,,so7 #ajj4b ,chlorid of ,sodium 7,na,cl7 #eh4f #dg4f ---------------------------------------- ----- ,these figures differ widely in most respects from those given for drain and river waters4 ,potash especially is far more abundantly present in the ,bonn-soil solution than in the drain water1 and so is phosphoric acid2 while lime is not widely different4 ,eichhorn therefore calculates that with a reasonably adequate supply of water1 these ingredients would fully suffice for a full crop of wheat4 ,the ,chemnitz soil1 on the other hand1 does not yield enough plant-food for more than a very small crop upon the same assumptions4 ,continuous ,solubility of ,soil-ingredients4--,it seems to be impossible to exhaust a soil's solubility by repeated or continuous leaching with water4 ,this was demonstrated in #ahfc and #ahfd by ,ulbricht#aaa and by ,schultze2#aab their general conclusions have quite lately been corroborated by ,king1#aac as the result of extended and very careful investigations4 ,schultze experimented on a rich soil from ,mecklenburg1 by continuous leaching with distilled water for six days1 one liter passing every twenty-four hours1 with the following results4 #aaa ,vers4 ,stat4 ,v4 p4 #bjg4 #aab ,ibid4 ,,vi4 p4 #daa4 #aac ,proc4 ,ass'n ,prom4 ,agr4 ,sci4 #aijd4 ,,rich ,,soil ,,from ,,mecklenburg 7,schultze47 #a1jjj1jjj ,,parts ,,of ,,extracts ,,contained3 ,total matter,organic and,inorganic4,phosphoric dissolved4 volatile4 acid4 ---------------------------------------- ----------------- ,first extract #ece4j #cdj4j #aie #e4f ,second 8 #abj4j #eg4j #fc #h4b ,third 8 #bfa4j #aja4j #afj #h4h ,fourth 8 #bjc4j #hc4j #abj #g4e ,fifth 8 #bfj4j #hb4j #agh #f4i ,sixth 8 #bjj4j #gg4j #abc #d4d ------- ----- --- ---- ,total #a1egi4j #gdj4j #hci #da4d ---------------------------------------- ----------------- ,it thus appears that while the first extraction removed the main portion of the organic matter1 the inorganic matters dissolved were not greatly diminished in subsequent leachings2 and that phosphoric acid continued to come off to the last4 ,the rich soil used in this case gave results corresponding in general to these from the ,bonn soil1 in the previous table4 ,from a poorer soil similarly treated by ,ulbricht1 described by him as a ferruginous sand from ,dahme1 the leaching of which was continued for thirty days in periods of three days each1 with a total of forty times its weight of water1 the results were as follows3 ,,soil ,,of ,,low ,,production ,,from ,,dahme 7,ulbricht74 ,,the ,,several ,,extracts ,,contained ,,in #a1jjj1jjj ,,parts3 ,first ,second ,third ,fourth ,fifth ,sixth ,extract4,extract4,extract4,extract4,ext ract4,extract4 ---------------------------------------- -------------------- ,potash #g #f #g #g #c ,soda #da #aa #bf #ag #h ,lime #if #gj #ee #dh #fb ,magnesia #ad #aj #i #g #h ,phosphoric acid trace #b trace #a ----- -- ----- -- -- -- ,totals #aeh #ii #ig #hj #gj #aa ---------------------------------------- -------------------- ,it will be seen that there is a considerable difference both in the total amounts of matters dissolved and in the phosphoric acid taken out by the water1 as compared with the rich soil treated by ,schultze4 ,the uniformity of the amounts of potash removed at the successive leachings is remarkable4 ,king's ,results4--,the same general features are again strikingly illustrated by ,king's results1 as given in the following table4 ,king's first leachings were always made by shaking up the soil with ten times its dry weight of water for three minutes1 then after subsidence filtering the solutions through a ,chamberland 7porcelain biscuit7 filter1 and then 7without evaporation7 determining the ingredients dissolved1 by very delicate1 mostly colorimetric methods4 ,subsequent leachings were made by packing the soil around the filters and washing with five times the weight of water1 taking about fifteen minutes each time2 but drying the soil at #abj degrees ,c4 between successive leachings4 ,,water ,,extraction ,,of ,,soils ,,of ,,low ,,and ,,high ,,production1 ,,by ,f4 ,h4 ,,king4 ,,parts ,,per ,,million4 ,potash1 ,lime1 ,magnesia1 ,nitric ,extractions ,k,o4 ,ca,o4 ,mg,o4 ,acid1 ,n,o4 ---------------------------------------- ----------------- ,,soils ,,of ,,low ,,production4 ,sassafras sandy #a #ab4fb #gd4ci #ag4hb #ah4jc soil4 #aa #bah4be #ace4ce #adg4de #ba4gf ---------------------------------------- ----------------- ,norfolk1 ,north #a #ba4ag #eh4cj #bb4ia #cj4fd ,carolina sandy soil #aa #aff4jh #afb4ih #abe4jj #bg4aa ,average4 #aib4fj #adi4bj #acf4bc #bd4dd ,,soils ,,of ,,high ,,production4 ,janesville1 ,wis4 #a #be4ce #ace4cj #ea4gb #ee4aj ,loam4 #aa #cac4gjaabj4cj #ejj4fj #ea4db ---------------------------------------- ----------------- ,hagerst'wn1 ,pa4 #a #ba4gc #afe4be #gf4hh #be4gb ,clay loam4 #aa #cja4ee #ifg4hj #dfc4ae #if4jd ,average4 #cjg4fjajdd4je #dhg4hh #gc4gc ---------------------------------------- ----------------- ,phosphoric,sulfuric,carbonic,chlorin1,s ilica ,extractions ,acid1 ,acid1 ,acid1 ,cl4 ,si,o4 ,p,o4 ,,so4 ,,co4 ---------------------------------------- ----------------------- ,,soils ,,of ,,low ,,production4 ,sassafras sandy #a #g4da #ec4hd #ac4id #a #e4fj soil4 #aa #fd4af #bjc4if #bba4cc #b #gj4bj ---------------------------------------- ----------------------- ,norfolk1 ,north #a #aj4ae #db4hb #bj4db #a #h4bd ,carolina sandy soil #aa #hj4cd #agb4db #adh4eb #b #abb4bj ,average4 #gb4be #abf4ac #ahd4ic #b4- #adf4bj ,,soils ,,of ,,high ,,production4 ,janesville1 ,wis4 #a #af4if #abe4dc #bi4ca #b4fg #dj4bh ,loam4 #aa #dah4he #eib4ge #dgb4ie #j4jj #dad4ej ---------------------------------------- ----------------------- ,hagerst'wn1 ,pa4 #a #aa4ea #ahg4ei #ig4ji #a4fg #ba4ag ,clay loam4 #aa #acf4ba #ejb4hb #fbj4jj #j4jj #bhc4hj ,average4 #bgg4jc #edg4gi #edf4dh #j4jj #cdi4ae ---------------------------------------- ----------------------- ,king's observations show strikingly both the continuous solubility of the soil1 and the differences between the solutions derived from soils of low and high productiveness2 wholly negativing the contention of ,whitney that the solutions from different soils are of practically the same composition4#aad ,king also calls attention to the fact1 shown in other experiments made in the extraction of soils without intermediate dryings1 that the amounts extracted were very much less in subsequent than in the first extraction2 doubtless because the evaporation from the soil particles had carried a large proportion of soluble matters to the surface1 whence it was readily abstracted by the first touch of the solvent water4 ,at each drying not only are the soluble matters again drawn to the surface1 but heating a soil even to #ajj renders additional amounts of soil ingredients soluble both in water and in acids4 ,it can scarcely be doubted that the intense heating which desert soils undergo during the warm season is similarly effective2 and thus the great productiveness of these soils under irrigation1 and the marvelously rapid development of the native vegetation when rains moisten the parched soil1 is in part at least accounted for by this immediate availability of a large supply of plant-food4 #aad ,bulletin ,no4 #bb1 ,bureau of ,soils1 ,u4 ,s4 ,d4 ,a4 ,composition of ,janesville loam4--,in connection with the above data given by ,king1 it is interesting to note the composition of the soil in the above table yielding the highest proportions of soluble matter1 when analyzed according to the method practiced by the writer 7see chap4 #ai1 p4 #cdc74 ,this analysis was made under the supervision of ,professor ,jaffa in the laboratory of the ,california ,experiment ,station by ,assistant ,charles ,a4 ,triebel4 ,loam ,soil from ,janesville1 ,wisconsin2 sample sent by ,prof4 ,f4 ,h4 ,king1 ,madison1 ,wis4 ,this soil is a light friable loam1 resembling the northern ,loess in color and texture2 it is highly productive4 ,it is underlaid at #e feet by the drift gravel of that region1 enclosing much calcareous material1 which evidently has had a large share in the formation of this soil1 just as is the case in southern ,michigan4 ,the soil1 when dried at #aaj ,c1 consisted of ,,chemical ,,analysis ,,of ,,fine ,,earth4 ,insoluble matter #fi4ce ,soluble silica #aj4hi ,potash 7,,ko7 4#ei ,soda 7,na,o7 4#jd ,lime 7,ca,o7 4#hc ,magnesia 7,mg,o7 4#ea ,br4 ox4 of ,manganese 7,mn,o7 4#jh ,peroxid of ,iron 7,fe,o7 #c4fj ,alumina 7,al,o7 #e4bf ,phosphoric acid 7,p,o7 4#jf ,sulfuric acid 7,,so7 4#aj ,water and organic matter #h4gb ------ ,total #ajj4jc ,it will be noted that in accordance with the interpretation of analyses of soils as given in the next chapter1 this is a high-class soil in every respect1 except that its content of phosphoric acid is only just above the lower limit of sufficiency4 ,but as is also shown below1 in presence of a large supply of lime even lower percentages of phosphoric acid are adequate for long-continued production 7see chap4 #ai1 pp4 #ced1 #cfe7 by rendering the substance more freely available2 and that this is true in this case is shown by the result of ,king's leachings1 in which this soil yields a maximum of #dai parts per million as against #hj and #fd parts in the poor soils1 which at the same time yield only one fourth as much of lime4 ,unfortunately we have no full analyses of these other soils for comparison2 although they have served as a basis of comparison for years in the ,washington ,bureau of ,soils4 ,solubility of ,soil ,phosphates in ,water4--,the solubility of the phosphate contents of soils has been elaborately investigated by ,th4 ,schloesing fils4#aae ,he found in the case of a number of soils investigated by him that the amount of phosphoric acid ,p,o in the soil-solution ranged from less than one millionth 7or one milligram per liter of water7 in a poor soil1 to over three milligrams in a rich one4 ,he also found that for one and the same soil the amount so found was constant1 if about a week's time were allowed for saturation4 ,he calculates that while in general the amount of phosphoric acid capable of being supplied to the crop during a growing season of twenty-eight to thirty weeks would suffice for but few crops1 the supply so afforded is in no case a negligible quantity1 frequently amounting to more than half of the crop-requirements4 ,experiments with various crops prove that these dilute solutions are utilized by all of them1 sometimes to the extent of completely consuming the content of the solution4 ,the much smaller content of phosphoric acid in drain waters is accounted for by the lack of time for full saturation during the time that the flow lasts4 ,whitney1 7,bureau of ,soils1 ,bulletin #bb7 has extracted the soil-solution by means of the centrifuge from several soils2 the contents of phosphoric acid thus found are in general of the same order as those shown in the preceding table by ,king1 but much in excess of ,schloesing's figures2 notwithstanding the fact that ,whitney's soils had been in contact with water for only twenty-four hours4 ,the cause of this wide discrepancy is not clear4 #aae ,ann4 de la ,sci4 ,agron41 #b;de srie tome ,i1 pp4 #daf-cdi2 #ahii4 ,practical ,conclusions from ,water ,extraction4--,as regards the practically useful conclusions to be drawn from the extraction of soils with pure water1 the data given above1 and especially the results obtained by ,king1 seem to prove that there is a more or less definite correlation between the immediate productiveness of soils and the amount and kinds of ingredients dissolved2 especially in the case of phosphoric acid1 the adequacy of the supply of which for immediate production is assumed to be thus demonstrable by many ,french chemists4 ,moreover1 a number of ,king's results1 tabulated in curves1 exhibit a remarkable general parallelism of the curves showing totals of plant-food extracted by water1 and actual crop production4 ,this is the more remarkable since it is known to be1 not pure water1 but such as is more or less impregnated with carbonic acid at least1 that is actually active in soil-solution and plant-nutrition4 ,the farther development of this method may1 it would seem1 lead to definite conclusions at least in respect to the immediate productive capacity of cultivated1 and perhaps also of virgin soils4 ,but it is not likely to give any definite clew as to the durability of such lands4 ,,ascertainment ,,of ,,the ,,immediate ,,plant-,,food ,,requirements ,,of ,,cultivated ,,soils ,,by ,,physiological ,,tests4 ,,physiological ,,soil-,,analysis4 ,as has already been stated1 the quantitative analysis of cultivated soils by means of strong acids affords a presumptive insight into their immediate productiveness1 and the kind of fertilizer needed to improve it1 only in case of the extreme deficiency of one or several of the chiefly important plant-foods4 ,the limits of deficiency of these in virgin soils have been discussed above2 but since in cultivated soils amounts of soluble plant-food so small as to be beyond the limits of ordinary analytical determinations1 when distributed through an acre-foot of soil may1 when rightly applied1 nevertheless produce very decided effects1 the indications thus obtainable are not absolute4 ,thus a dressing of #aej lbs4 of ,chile saltpeter1 containing only about #bd lbs4 of nitrogen1 is capable of causing the production of a full crop of wheat where otherwise1 even under favorable physical conditions1 only a fraction of a crop would have been harvested2 provided1 that all the other requisite ingredients were present to a sufficient extent and in available form4 ,yet the amount of nitrogen thus added would amount1 in one acre-foot of soil to only 4#jjjh1 say eight ten-thousandths of one percent2 which1 with the amounts of substance usually employed in soil analysis1 would be an unweighable quantity1 and might easily be overlooked4 ,since the amounts of potash and phosphoric acid actually taken out of the soil by one crop are in general of the same order of magnitude as the above1 what is taken out by one or two crops will usually fall within the limits of analytical errors1 especially of those incurred in sampling the soil4 ,yet that the changes caused by a number of successive crops can be proved1 even by the ordinary methods1 has been abundantly verified4 ,for it seems that the losses of soil ingredients in cultivated lands exceed considerably those calculated from the actual drain represented by the crops4 ,plot ,tests4--,there is1 however1 an obvious and apparently simple method by which every farmer might make his own fertilizer tests1 on a small and inexpensive scale1 the results of which may afterwards be put in effect on his entire land4 ,it is to apply in proper proportions on plots 7of say from one twentieth to one fortieth of an acre71 the several plant-food ingredients usually supplied in fertilizers1 singly as well as conjointly with each other1 leaving check unfertilized plots around as well as among them4 ,by comparison with these1 the cultural results should at once determine which of the fertilizers can most advantageously be applied to the land4 ,such tests when carried out with all the proper precautions are often very decisive and practically successful4 ,but they so frequently suffer from seasonal influences 7such as scanty or excessive rainfall1 cold or heat1 etc471 inequality of soil conditions1 failure to apply the fertilizers at the right time1 or in the right way1 the depredations of insects and birds1 and other causes1 that it generally takes several seasons' trial to obtain any definite results4 ,on level lands of uniform nature and depth1 they are most likely to be successful2 while on undulating or hill lands it is not only very difficult to secure uniformity of soil and subsoil on areas of sufficient size1 but also to prevent the washing of fertilized soil1 or fertilizer in solution1 from one plot to the other by the influence of heavy rains or irrigation2 thus wholly vitiating the experiments4 ,in very many cases1 especially in the arid region1 the results of such trials have been practically nil1 for the reason that physical defects of the soil1 and not lack of plant-food1 were the cause of unsatisfactory production4 ,illustration3 ,scheme for ,plot-tests of ,fertilizers4 ,a full examination of physical conditions1 as outlined in previous chapters1 should in all cases precede the application of fertilizers2 such examination will at the same time serve to determine the greater or less uniformity of soil-conditions1 which is of first importance to the cogency of fertilizer tests4 ,as a matter of fact1 few farmers possess the necessary qualifications to carry out such tests successfully1 since their execution requires a certain familiarity not only with the principles and methods of experimentation1 but also the faculty and practice of close and reasoning observation2 which1 unfortunately1 is not as yet a part of instruction in our schools4 ,the experience so often had in co-operative work between experiment stations and farmers is cogent on this point4 ,those desiring to do such work1 however1 can make use of something like the plan given above2 it being understood that in the case of clay soils1 the unplanted paths left between the plots should be at least two feet in width2 in the case of sandy soils the distance should be not less than three feet1 and more if the plots are located on a slope4 ,the crop from each plot should if possible be weighed as a whole2 but if the plot be large and the crop measurably uniform1 an aliquot part1 such as one fourth1 may be weighed instead4 ,in regular experimentation the crops are weighed both in the green 7freshly cut7 condition1 and after drying4 ,since the dry matter is the real basis of value in the case of most field crops1 its weight is the most important2 as the water-content of green crops may vary considerably4 ,but in the case of vegetables as well as fruit crops1 not only must the weight of the fresh crop be determined1 but it should be sorted into the 8marketable0 and 8unmarketable0 sizes and qualities4 ,failure to do this may vitiate the entire experiment for practical purposes4 ,pot ,culture ,tests4--,the uncertainty attending plot culture tests on account of the difficulty of controlling seasonal and other external conditions1 has resulted in the extended adoption of indoor culture tests1 usually conducted in zinc or 8galvanized0 cylinders of a size sufficient to contain from twelve to twenty or more pounds of soil4 ,these are kept in a green-house whose temperature and moisture-condition can be regulated at will1 and where the soil-moisture is wholly under control4 ,for investigations of the effects of various kinds of plant-food upon vegetable development1 this method has served most satisfactorily and effectually1 and striking photographs of results thus obtained are seen on all hands3 for which reason1 to save space1 they have not been introduced into this volume4 ,it seems at first sight that the same method should serve admirably to determine the manure-requirements of soils under controlled conditions4 ,it must1 however1 be remembered that the field conditions as regards subsoil1 evaporation1 ascent of moisture from below1 penetration and spread of roots1 etc41 in other words1 all the physical conditions so vitally concerned in crop production1 except the temperature and moisture-condition of the soil1 are wholly left out of consideration in this method4 ,hence the application of the results so obtained to actual field conditions can only be made with great caution1 and are often widely discrepant with actual experience4 ,the method has of late been carried to an extreme by the ,u4 ,s4 ,bureau of ,soils in the proposition to supplant the large soil-pots heretofore used by small paraffined wire-cloth baskets1 #c #c inches in size1 in which the soil to be tested is sown with seeds which are allowed to develop only for three to five weeks2 it being claimed that the development occurring during that time is quite sufficient to indicate what will be the ultimate outcome in crop production4 ,but practical experience has long ago demonstrated that these early stages of growth cannot be relied upon to show the crop results to be expected4 ,yet if this minute scale of pot-culture should1 on further test1 prove to give truthful forecasts even in a mere majority of cases1 the facility with which it may be carried out will entitle it to favorable consideration4 ,a great deal more proof is needed on this point than the confident claims of the ,bureau indicate4 ,,chemical ,,tests ,,of ,,immediate ,,productiveness4 ,testing chemical soil-character by crop analysis4--,another method for the determination of immediate soil requirements has been elaborated by ,e4 ,godlewski4#aaf ,the principle upon which this method rests is that plants growing in a soil deficient in available plant-food of any one kind will in their ash show a corresponding deficiency1 or at least a minimum proportion of the same2 and that in many cases1 the nature of the deficiency manifests itself in the form or development of the plant1 so clearly as to render chemical analysis unnecessary 7see below1 chapter #bb74 #aaf ,zeitschr4 ,landw4 ,vers4 ,oesterr41 #aija4 ,to a certain extent the latter idea has been and is constantly being utilized in practice4 ,it is essentially involved in the habit of judging of land by its natural vegetation2 and by agricultural chemists and intelligent farmers1 when they check excessive growth of stems and leaf 7indicating excess of nitrogen7 by the use of lime or phosphates2 or prescribe the use of nitrogenous manures when a superabundance of small1 unmarketable fruit is produced4 ,from the coincidence of such indications with the results of the analyses of soils and ashes1 very definite and permanently valuable indications as to the proper fertilization and other treatment of the land may be deduced4 ,godlewski insists strongly1 and with a good deal of plausibility1 upon the importance of making such trials in the open field and not merely in pots4 ,while this is true1 it is also true that such field experiments suffer from the same liability to imperfection as the 8plot fertilizer-test0 plan just described2 viz41 that the season may exert a much more powerful influence than the fertilization1 and the tests may lead to wholly erroneous conclusions unless the experiments are continued for a number of years1 and under skilled supervision4 ,but when once the normal ratio between the ash ingredients for a particular soil and climatic region have been ascertained1 the data will be of lasting benefit to agriculture there1 and perhaps1 other things being equal1 to the world at large4 ,h4 ,vanderyst has discussed the entire subject of physiological soil analysis elaborately in the ,revue ,gnerale ,agronomique of ,louvain1 #aijb-c 7,exp't ,st4 ,record1 ,april #aijd1 ,vol4 #h1 page #geg7 and shows in detail the conditions under which it may be successful4 ,among these he reckons as full a knowledge of the chemical characteristics of a soil as can be obtained by chemical analysis4 ,chemical ,tests of ,immediately ,available ,plant-food4--,it is scarcely doubtful that plants differ considerably in the energy of their action upon the 8reserve0 soil ingredients2 hence no one solvent used by the analyst could represent correctly the action of plant-roots in general upon the soil1 even if we could give that action the same time 7a growing season7 and opportunity afforded them in nature by the root-surface4 ,we are forced to proceed empirically2 and among the numerous solvents suggested for the purpose of soil extraction1 that of ,dyer1 already mentioned1 viz41 a one per cent solution of citric acid1 making allowance for such neutralization as may occur in the soil1 has seemed to the writer to give results most largely in agreement with cultural experience4 ,walter ,maxwell has recommended aspartic acid in lieu of citric1 as approaching nearer to practical results1 at least with sugar-cane4 ,according to the investigations of ,dyer1 on ,rothamstead soils of known productiveness or manurial condition1 it appears that when the citric-acid extraction yields as much as 4#jje of potash and 4#jaj of phosphoric acid1 the supply is adequate for normal crop production1 so that the use of the above substances as fertilizers would be1 if not ineffective1 at least not a profitable investment4 ,these figures refer to the ordinary field crops of ,england and to soils originally fertile and well supplied with lime4 ,it can readily be foreseen that under other climatic and soil conditions1 different figures may have to be established4 ,so far as the writer's experience goes1 however1 the above figures are very nearly valid for the arid climates as well2 only the figures obtained for arid soils are usually far in excess of the above minimum postulates4 ,figures for lime and nitrogen are given in chapters #h and #ai4 ,but the results obtained with the highly ferruginous soils of ,hawaii show that under such conditions1 figures far exceeding the minimum ones established by ,dyer nevertheless coexist with need of phosphate fertilization4 ,,chapter ,,xix4 ,,the ,,analysis ,,of ,,virgin ,,soils ,,by ,,extraction ,,with ,,strong ,,acids4 ,as stated already1 the analysis of soils by extraction with strong acids is intended to enlighten us1 not in regard to their immediate productiveness 7the 8,dngerzustand0 of ,german agricultural chemists71 but as to their permanent value or productive capacity4 ,as has been seen in the preceding chapter1 the efforts to unite investigators upon a generally applicable and acceptable method for the testing of immediate productiveness have not been very successful1 and the number of methods employed in different countries and by different chemists within the same country are widely at variance1 with no immediate prospect of agreement4 ,moreover1 in most cases the effort is to combine both problems--temporary and permanent productive capacity--in one method or operation2 which still farther confuses the issue4 ,convinced that the only way to unification lies in the direction of falling back upon a method that is based upon a natural limitation about which there can be no difference of opinion1 the writer has1 in following the lead of ,owen and ,robert ,peter1 endeavored to settle definitely the natural limit of the action of a suitable acid upon soils1 and the time and strength of acid producing the maximum effect4 ,loughridge's ,investigation4--,systematic work on these points was undertaken1 at his suggestion1 by ,dr4 ,r4 ,h4 ,loughridge in #ahga and #ahgb4 ,the results of this work were published in the succeeding year in the ,amer4 ,journal of ,science1 and in the proceedings of the ,a4 ,a4 ,a4 ,s4 for #ahgc4 ,they seem to be of sufficient general interest to be reproduced here4 ,the soil selected for this purpose was a very generalized one1 representing large areas in the states of ,kentucky1 ,tennessee1 ,mississippi and ,louisiana1 bordering on the east the immediate valley of the ,mississippi river1 and known locally as the 8,table lands20 a noted cotton-producing upland region4 ,the brown or yellow1 moderately clayey loam is of great uniformity throughout its region of occurrence1 and is evidently derived from such widely-spread sources that it represents no special rock or complex of rocks4 ,its natural growth is a mixture of oaks and hickories1 strong and well-developed trees1 such as any land-seeker would at once approve for settlement4 ,its cotton product when fresh was a #djj-pound bale of cotton lint per acre4 ,it may therefore well be considered a typical generalized soil of the humid upland of the ,mississippi valley4 ,its physical analysis is given in chapter #f1 it being ,no4 #bai of the table on p4 #ih4 ,strength of ,acid used4--,three different strengths of acid were simultaneously employed1 viz41 chlorhydric of #a4aj1 #a4aae and #a4afj density4 ,with these the soil was digested at steam heat in porcelain beakers covered with watch glasses for five days each1 then evaporated and analyzed as usual4 ,the results were as follows3 ,,analysis ,,with ,,acid ,,of ,,different ,,strengths4 ,ingredients4 ,sp4 ,g4 of ,acid4 ---------------------------------------- -------- #a4aj #a4aae #a4afj ----------------------- ,insoluble residue #ga4hh #gj4ec #gd4ae ,soluble silica #aa4ch #ab4cj #i4db ,potash 4#fj 4#fc 4#dh ,soda 4#ac 4#ji 4#ce ,lime 4#bg 4#bg 4#bc ,magnesia 4#de 4#de 4#de ,br4 ox4 ,manganese 4#jf 4#jf 4#jf ,ferric ,oxid #e4ae #e4aa #e4jd ,alumina #f4hd #h4ji #f4bb ,sulfuric acid 4#jb 4#jb 4#jb ,volatile matter #c4ad #c4ad #c4ad ------ ------ ----- #ajj4jb #ajj4fi #ii4bi ,amount of soluble matter #bd4jj #bg4jb #bb4bg ,amount of soluble bases #ac4ej #ad4gj #ab4hc ---------------------------------------- -------- ,it will be noted that the strongest acid produced the smallest amount of decomposition of the soil silicates1 e4 g4 the silica soluble in carbonate of soda solution being #c less than in the case of the acid of medium strength2 a result possibly due to some difficultly-soluble compound formed on the surface of the soil grains4 ,the weakest acid had a stronger solvent power2 but the maximum effect was produced by the acid of #a4aae density4 ,this being also the most readily obtainable1 by simple steam distillation of acid of any other strength1 the writer adopted it as best suited to the purposes of soil analysis4 ,to ascertain the time required for the desired action1 viz41 the solution of the plant-food ingredients to the extent likely to be of any avail to growing plants1 digestions of the same soil were made in the same manner for periods of #a1 #c1 #d1 #e and #aj days1 with the acid of #a4aae density4 ,the results were as follows3 ,,analysis ,,after ,,different ,,times ,,of ,,digestion4 ,no4 of ,days' ,digestion4 ,ingredients4 ------------------------------ #a #c #d #e #aj ---------------------------------------- --------------- ,insoluble ,residue #gf4ig #gb4ff #ga4hf #gj4ec #ga4gi ,soluble ,silica #h4fj #aa4ah #aa4fd #ab4cj #aj4if ,potash 4#ce 4#dd 4#eg 4#fc 4#fb ,soda 4#jf 4#jf 4#jc 4#ji 4#bh ,lime 4#bf 4#bi 4#bh 4#bg 4#bg ,magnesia 4#db 4#dd 4#dg 4#de 4#dd ,br4 ,ox4 ,manganese 4#jd 4#jf 4#jf 4#jf 4#jf ,ferric ,oxid #d4gg #e4ja #e4dc #e4aa #d4he ,alumina #e4ae #g4ch #g4jg #g4hh #g4af ,phosphoric acid 4#ba 4#ba 4#ba 4#ba 4#ba ,sulfuric acid 4#jb 4#jb 4#jb 4#jb 4#jb ,volatile matter #c4ad #c4ad #c4ad #c4ad #c4ad ------------------------------ ,total #ii4fcajj4fhajj4eeajj4fi #ii4hj ,amount of soluble matter #ai4fg #bd4hh #be4eg #bg4jb #bd4hg ,amount of soluble bases #aa4je #ac4fh #ac4ia #ad4di #ac4fh ---------------------------------------- --------------- ,while these results pointed clearly to the five-day period as being sufficiently effective so far as the plant-food ingredients are concerned1 it was not easy to understand why a ten-day digestion should be less incisive than a five-day one4 ,instead of repeating the ten-day experiment1 it was thought preferable to re-treat the residue from the five-day digestion for five days more4 ,the result was that only more silica and alumina went into solution--in other words1 additional clay was alone being decomposed4 ,this being of no interest in the matter of plant nutrition1 the five-day period was definitely adopted by the writer for his work2 and it1 together with the acid of #a4aae density1 is the basis of all the results given in this volume1 except where otherwise stated4 ,there appeared to him to be no good reason for the acceptance of the arbitrary method of soil-extraction suggested by ,kedzie and since adopted by the ,association of ,official ,agricultural ,chemists2 the more as to do so would throw out of comparison all the previous work done by ,owen1 ,peter1 and himself and his pupils1 which had already been definitely correlated with the natural conditions and with cultural experience4#aag #aag ,while regretting to thus 8secede0 from the fellowship of his colleagues1 the writer cannot but regret equally their voluntary decision to do over again1 or lightly reject1 all that had been done before in correlating soil-composition and plant-growth4 ,he still thinks that it is idle to expect any unification1 national or international1 of methods of soil analysis based upon purely arbitrary prescriptions1 unless previously shown to be definitely correlated with natural and cultural conditions2 as is measurably the case with ,dyer's method4 ,virgin ,soils with ,high ,plant-food ,percentages are ,always ,productive4--,in strong contrast to the contradictory evidence deduced from the analysis1 by any method1 of cultivated soils when compared with cultural experience1 it seems to be generally true that virgin soils showing high percentages of plant-food as ascertained by extraction with strong acids 7such as hydrochloric1 nitric1 etc471 invariably prove highly productive3 provided only that extreme physical characters do not interfere with normal plant growth1 as is sometimes the case with heavy clays1 or very coarse sandy lands4--,to this rule no exception has thus far been found4 ,the composition of some representative soils falling within this category is given in the annexed table1 which at the same time conveys some idea of the proportion of acid-soluble ingredients usually found in the best class of natural soils4 ,,table ,,exemplifying ,,high ,,plant-,,food ,,percentage ,,in ,,soils4 7,a7 ,buckshot soil4 ,yazoo ,bottom4 7,b7 ,black ,prairie4 ,rankin ,county4 7,c7 ,loamy ,sediment4 ,houma1 ,terrebonne parish4 7,d7 ,rio ,grande ,bottom4 ,sandy ,sediment4 ,mississippi ,louisiana4 ,texas4 ------------------------------------- 7,a7 7,b7 7,c7 7,d7 7,heavy ,clay74 7,loam74 ---------------------------------------- ------------------------- ,number of ,sample #cij #ahh #bdj #cg ---------------------------------------- ------------------------- ,chemical ,analysis of ,fine ,earth4 ,insoluble matter #ea4jf #fi4ie #ce4dh #cf4jd #ga4gg #gd4dj #ef4bd #ec4cj ,soluble silica #bj4gj #d4df #bj4gf #ag4bf ---------------------------------------- ------------------------- ,potash 7,k,o7 #a4aj 4#ij #a4jc #a4ca ,soda 7,na,o7 4#cc 4#bd 4#ac 4#bb ,lime 7,ca,o7 #a4ce #a4jd 4#gb #ad4dc ,magnesia 7,mg,o7 #a4fg 4#ia 4#hh #a4ec ,br4 ox4 of ,manganese 7,mn,o7 4#ab 4#ab 4#jad 4#jg ,peroxid of ,iron 7,fe,o7 #e4hb #d4gg #g4aj #d4ji ,alumina 7,al,o7 #aj4ed #g4be #ae4de #i4aa ,phosphoric acid 7,p,o7 4#cj 4#dg 4#ae 4#bj ,sulfuric acid 7,,so7 4#jb 4#af 4#be 4#jd ,carbonic acid 7,,co7 #i4ia ,water and organic matter #g4cg #aj4gd #ah4eb 8 ---------------------------------------- ------------------------- ,total #ajj4ch #aja4ja #ajj4dh #ajj4bb ---------------------------------------- ------------------------- 7,e7 ,san ,diego ,co4 ,colorado ,bottom4 ,silt ,sediment4#aah 7,f7 ,riverside ,co4 ,palm ,valley4 ,micaceous ,sandy ,soil4 7,g7 ,tulare ,co4 ,experiment ,station4 ,plains ,loam4 7,h7 ,solano ,co4 ,putah ,valley4 ,dark ,loam4 7,i7 ,san ,luis ,obispo ,co4 ,arroyo ,grande ,dark ,loam4 ,california4 ------------------------------------- 7,e7 7,f7 7,g7 7,h7 7,i7 ---------------------------------------- ------------------------- ,number of ,sample #ejf #ajib #aaei #aaj #bjfa ---------------------------------------- ------------------------- ,chemical ,analysis of ,fine ,earth4 ,insoluble matter #eh4eg #ga4de #gb4ihfg4cc #ec4dc #fc4ij #ga4jj #gb4dc ,soluble silica #e4cc #e4ej #f4fj #c4fg #ai4jj ---------------------------------------- ------------------------- ,potash 7,k,o7 #a4ah #a4db #a4bj 4#ic 4#fg ,soda 7,na,o7 4#af 4#ah 4#eb 4#ab 4#ah ,lime 7,ca,o7 #h4fg #b4bj #a4hf 4#gg #b4aa ,magnesia 7,mg,o7 #b4ig #b4ji #a4ha #b4bi #b4bf ,br4 ox4 of ,manganese 7,mn,o7 4#jc 4#je 4#jh 4#aa 4#jf ,peroxid of ,iron 7,fe,o7 #d4ad #f4fh #f4hf #h4ja #e4bc ,alumina 7,al,o7 #h4dj #e4gh #e4ff #i4af #g4dj ,phosphoric acid 7,p,o7 4#ac 4#ce 4#aj 4#aa 4#ga ,sulfuric acid 7,,so7 4#ae 4#ja 4#jc 4#ab 4#bb ,carbonic acid 7,,co7 #g4hb 4#ah #a4hb ,water and organic matter #c4cd #d4bi #b4ed #g4ab #f4fc ---------------------------------------- ------------------------- ,total #ajj4hi #ajj4ahajj4bdii4gd #ii4gb ,humus #c4jf ,nitrogen in humus #bb4jj ,nitrogen in soil 4#fg ,hygroscopic moisture4 absorbed at #ae;,c #aj4gj ---------------------------------------- ------------------------- ,available phos4 acid 4#ad ,available potash 4#ad #aah ,the ,rio ,grande and ,colorado bottom soils contain amounts of lime carbonate largely in excess of requirements1 #b to #c of that compound being all that is needed to insure all the advantageous effects of lime in any soil 7see this chapter1 page #cfg74 ,discussion of ,table4--,it will be noted in this table that while the total of the matters soluble in acids 7inclusive of silica7 ranges from a little below #ej to over #gg per cent1 the total of directly important mineral plant-food ingredients 7potash1 lime1 magnesia and phosphoric acid71 constitute in moderately calcareous soils only from about #b4e to somewhat over four per cent of the whole4 ,yet if all these were in available form1 the supply would be abundant for many hundreds and even thousands of crop years4 ,for1 one-tenth of one per cent in the case of the clayey soils of the preceding table would amount to about #cejj pounds per acre-foot1 and to #djjj in the case of the sandy ones4 ,hence the amount of phosphoric acid in e4 g41 the ,mississippi delta soil from ,houma would suffice for the production of about #ddj crops of wheat grain 7at #bj bushels per acre7 if only one foot depth were drawn upon2 but as the roots of grain easily penetrate to twice and half and three times that depth even in the humid region1 the number might be tripled4 ,as a matter of fact1 however1 that soil has produced full crops for from forty to fifty years only2 yet this is considered an exceptionally long duration of profitable production without fertilization4 ,the first and last soils in the above list represent probably the highest types of productiveness known4 ,the ,yazoo bottom soil has produced up to one thousand pounds of cotton lint per acre when fresh1 and is still producing from four to five hundred pounds after thirty years' culture4 ,the ,arroyo ,grande soil of ,california with its extraordinary percentages of phosphoric acid and nitrogen1 as well as exceptionally high proportion of available phosphoric acid and potash1 has made such a record of productiveness1 and high quality of the seeds produced1 that it has for a number of years been excluded from competition for prizes offered by seed-producers elsewhere1 in order to give other sections a chance4 ,both these soils are rather heavy clays1 but readily tillable in consequence of their abundant lime-content4 ,the remarkably high content of acid-soluble silica1 indicating the presence of much easily available zeolitic matter1 is doubtless connected with the exceptional productiveness4 ,experience1 then1 proves that lands showing such high plant-food percentages will yield profitable harvests for a long time without fertilization1 or with only such partial returns as are afforded by the offal of crops4 ,also that when fertilization comes to be required1 instead of supplying all the ingredients usually constituting fertilizers1 only one or two of these will as a rule be actually needed1 and even these in smaller amounts than in 8poor0 lands2 thus materially reducing the expense of fertilization4 ,the high production and durability of such lands therefore amply justify their higher pecuniary valuation2 for which there would be no rational permanent ground if they required fertilization to the same extent as poor lands4 ,in other words1 if the entire amount of soil-ingredients removed by crops had had to be currently replaced equally in all cases 7as is implied in the hypothesis1 advanced by some1 that the chemical composition of soils is of no practical consequence71 the high prices which from time immemorial have been paid for black prairie and rich alluvial lands as against meagre uplands and barrens1 would have been so much money wasted4 ,the explanation of these advantages evidently lies largely in the larger amounts of soil ingredients annually rendered available in rich soils by the fallowing effect of the atmospheric agencies1 because of the generous totals present4 ,the actual amounts of soil ingredients thus rendered accessible to plants1 other things being equal1 are evidently more or less directly proportional to the totals of acid-soluble plant-food ingredients present4 ,and if this is true in cultivated lands1 the inevitable conclusion is that the same must be true of virgin lands2 whose productive capacity and duration can therefore be forecast by such analyses4 ,it will be observed that the above data1 which could be indefinitely increased by corroborative analyses1 seem to establish the fact that about one per cent of acid-soluble potash1 one of lime1 the same1 or less1 of magnesia1 and 4#ae of phosphoric acid1 are thus shown to be 8high0 percentages of these ingredients in virgin soils4 ,it is not easy to see how the above conclusions can be successfully controverted2 they are1 moreover1 thoroughly in accordance with cultural experience4 ,difficulties of interpretation arise mainly in the case of medium soils1 which show neither very high nor very low percentages of plant-food2 and which raise the question of what amount or percentage constitutes 8adequacy0 of each of the several substances4 ,low ,percentages4--,on the other hand1 whenever in virgin soils acid-analysis shows the presence of but a very small proportion of one or several of the essential ingredients1 we have a valuable indication as to the one of these that will first be required to be added when production slackens4 ,what are 8,adequate0 ,percentages of ,potash1 ,lime1 ,phosphoric ,acid and ,nitrogen8--,it is evident that a very critical discussion of cultural experience can alone answer this question2 and at first sight such experience often appears very contradictory when compared with the results of analysis4 ,one of the chief causes of such apparent discrepancies is readily intelligible when we consider the differences in root-development of the same plant in different soils4 ,in 8light0 or sandy lands the roots may penetrate to several times the depth attained by them in heavy clay soils4 ,having thus within their reach a soil-mass several times larger1 and aerated to a much greater depth1 it is but reasonable to expect that in deep1 sandy lands plants would do equally well with correspondingly smaller percentages of plant-food than would suffice in clay soils1 in which the root-range is very much more restricted4 ,the well-known fact that the production of heavy clay lands may be increased by their intermixture with mere sand1 adding nothing to their store of plant-food1 emphasizes this expectation and elevates it into a maxim4 ,on this ground alone1 therefore1 it is evident that the mere consideration of plant-food percentages found1 can be a true measure of productiveness only in the case of virgin soils with high percentages4 ,soil ,dilution ,experiments4--,the extent to which dilution with mere 8lightening0 materials can be carried without impairing production1 can of course be determined for concrete cases only2 but the following experiment made at the ,california ,station is a case in point3 ,one kilogram of the heavy but highly productive black clay soil of the experimental grounds of the ,university of ,california was used in each of five experimental cultures1 each made in duplicate1 in cylindrical vessels of zinc-covered 78galvanized07 sheet iron1 all proportioned alike in height and diameter1 but containing respectively one1 two1 four1 five and six volumes of total soil4 ,in the smallest was placed one kilogram of the undiluted1 original soil1 in the others successively the same amount of the soil thoroughly mixed with one1 three1 four1 and five volumes of a dune sand fully extracted with chlorhydric acid1 and washed with distilled water4 ,the water capacity of each of the mixtures was determined and the earth in the pots kept at the point of half-saturation generally admitted to be the optimum 7best condition7 for plant growth4 ,each pot was sown with ten seeds of white mustard1 subsequently reduced to five plants selected for their vigor4 ,illustration3 ,,fig4 #ec4--,natural ,adobe ,clay ,soil4 ,illustration3 ,,fig4 #ed4--;,adobe ,soil diluted with sand1 #a to #a4 ,illustration3 ,,fig4 #ee4--,same1 diluted #a to #c4 ,,development ,,of ,,roots ,,of ,,white ,,mustard ,,in ,,clay ,,soil1 ,,diluted ,,with ,,various ,,proportions ,,of ,,pure ,,sand4 ,the 78galvanized07 vegetation pots were made as nearly as possible of similar proportions in depth and width for each dilution1 so as to give opportunity for the proportional development of the root systems4 ,the photographs show the latter as nearly as practicable in their natural form1 restored after washing off the adherent soil4 ,it was of course extremely difficult to preserve intact the extreme circumferential rootlets and hairs2 yet the general development is correctly shown4 ,illustration3 ,,fig4 #ef4--;,adobe ,soil diluted #a to #d4 ,illustration3 ,,fig4 #eg4--;,adobe ,soil diluted #a to #e4 ,illustration3 ,,fig4 #eh4--,soil-dilution ,experiment3 ,photograph showing ,mature ,plants4 ,the following table shows the percentage composition of the original as well as the diluted soils1 while the photographs show the development of the plants in their successive stages1 so far as these could be observed2 the continued attacks of mildew and plant lice preventing full maturity being attained4 ,,composition ,,of ,,black ,,adobe ,,and ,,sand ,,dilutions4 ,original ,dilutions4 ,chemical analysis of soil4 fine earth4 #a3j #a3a #a3c #a3d #a3e ---------------------------------------- ----------------------- ,insoluble matter #ed4ej #gg4be #hh4fb #ij4jj #ib4db ,soluble silica #ai4fj #i4ej #d4ge #c4hj #c4ag ,potash 7,k,o7 4#gc 4#cf 4#ah 4#ae 4#ab ,soda 7,na,o7 4#bj 4#aj 4#je 4#jd 4#jc ,lime 7,ca,o7 #a4ae 4#eg 4#bi 4#bc 4#ai ,magnesia 7,mg,o7 #a4jh 4#ed 4#bg 4#bb 4#ah ,br4 ox4 of ,manganese 7,mn,o7 4#jd 4#jb 4#ja 4#ja 4#ja ,peroxid of ,iron 7,fe,o7 #h4dc #d4bb #b4aa #a4fh #a4dj ,alumina 7,al,o7 #g4ib #c4if #a4ih #a4eh #a4cb ,phosphoric acid 7,p,o7 4#ai 4#aj 4#je 4#jd 4#jc ,sulfuric acid 7,,so7 4#jd 4#jb 4#ja 4#ja 4#ja ,carbonic acid 7,,co7 ,water and organic matter #f4ed #c4bg #a4fd #a4ca #a4ji ,loss in analysis #a4ah 4#ji 4#jd 4#jc 4#jc ----------------------------------- ,total #ajj4jj #ajj4jj #ajj4jj #ajj4jj #ajj4jj ,humus #a4ba 4#fj 4#cj 4#bd 4#bj 8 ,ash 4#id 4#dg 4#bc 4#ai 4#af 8 ,nitrogen1 p4 cent in ,humus #ah4eh #ah4eh #ah4ej #ah4eh #ah4eh 8 8 p4 cent4 in soil 4#bjc 4#aj 4#je 4#jd 4#jcd ---------------------------------------- ----------------------- ,the restricted volume of soil occupied by the roots in the undiluted adobe soil1 together with the very abundant development of root-hairs1 is very striking4 ,a marked change in these respects is manifest in the first dilution1 and increasingly so as dilution increases2 the paucity of root-hairs is very marked in the last 7greatest7 dilution1 in which1 as the photograph of the plants shows1 the development was decidedly behind that in the pot containing dilution #a3d4 ,the latter in fact showed the best development not only in this case1 but in two other series of tests conducted at the same and subsequent times2 and strangely enough1 also in the pulverulent1 8sandy loam0 soil of the southern ,california substation tract4 ,in the latter series1 which for lack of space cannot be figured here1 the main difference was that in the undiluted soil the roots filled the entire soil mass1 instead of remaining near the surface1 as in the pure adobe4 ,it is possible that the latter was too wet when given the full half of its water-capacity1 although1 as the figures show1 the water was slowly introduced from below by means of glass tubes1 ending within a shield to prevent puddling4 ,limitation of ,root ,action4--,these results1 representing five soils of different percentage-composition and physical character1 but identical chemical composition and ratios between the several ingredients1 and similarly acted upon by the atmospheric agencies in the past1 illustrate strikingly the impossibility of judging correctly of a soil's productiveness from percentages of chemical ingredients alone4 ,it is clear that the physical characters of the land as well as its depth1 must be essentially taken into account4 ,but there is obviously a certain limit beyond which greater perviousness and root-penetration cannot make up for deficiency in the absolute amounts of plant-food within possible reach of the plant2 for in the case of excessive dilution these are rendered partially inaccessible within the time-limits of a season's growth4 ,it is hardly necessary to say that these experiments require repetition with the aid of the experience acquired in these first trials1 not only in the laboratory but also in the field4 ,it will be especially interesting to compare with the results obtained in these strongly calcareous soils1 the effects of dilution in such soils as those of ,florida1 mentioned below2 the probability being that where lime is naturally deficient1 the effects of dilution will be much more pronounced in diminishing production1 because of the absence of the previous favorable action of lime upon the availability of the soil-ingredients4 ,lowest ,limit of ,plant-food ,percentages and ,productiveness found in ,virgin ,soils4--,the subjoined table shows some of the very low plant-food percentages found in natural soils1 all being of a sandy character3 ,,mississippi ,,soils4 --------------------------------- ,homochitto ,shell ,pine ,pine ,bottom4 ,hammock4 ,woods4 ,flats4 ---------------------------------------- --------------------- ,number of ,sample4 #fh #hc #bjf #bad ---------------------------------------- --------------------- ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- -------------------- ,insoluble matter #ib4af #if4jh #ic4bc #ie4ei ,soluble silica ---------------------------------------- -------------------- ,potash 7,k,o7 4#ae 4#je 4#bf 4#jf ,soda 7,na,o7 4#jd 4#jf 4#jg 4#je ,lime 7,ca,o7 4#ab 4#aj 4#ab 4#jb ,magnesia 7,mg,o7 4#ba 4#ab 4#ah 4#jg ,br4 ox4 of ,manganese 7,mn,o7 4#bh 4#je 4#ae 4#je ,peroxid of ,iron 7,fe,o7 #a4ah 4#eb #a4be 4#df ,alumina 7,al,o7 #c4bb 4#df #b4cf 4#he ,phosphoric acid 7,p,o7 4#jh 4#aj 4#jc 4#jb ,sulfuric acid 7,,so7 4#je ,trace 4#jb ,trace ,carbonic acid 7,,co7 ,water and organic matter #b4gj #c4jb #b4cc #b4bh ---------------------------------- ,total #ajj4ai #ajj4ef #ajj4jj #ii4de ---------------------------------------- ---------------------- ,,florida ,,soils4 -------------------- ,pine ,lands4 ------------------- ,first ,second ,class4 ,class4 ---------------------------------------- ------- ,number of ,sample4 #f #g ---------------------------------------- ------- ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ------- ,insoluble matter #id4df #ie4fc #if4ea ,soluble silica #a4fg 4#hh ---------------------------------------- ------- ,potash 7,k,o7 4#ai 4#ab ,soda 7,na,o7 4#jd 4#jf ,lime 7,ca,o7 4#jg 4#jf ,magnesia 7,mg,o7 4#jd 4#jd ,br4 ox4 of ,manganese 7,mn,o7 4#jf 4#je ,peroxid of ,iron 7,fe,o7 4#cb 4#bb ,alumina 7,al,o7 4#ib 4#dg ,phosphoric acid 7,p,o7 4#aa 4#ji ,sulfuric acid 7,,so7 4#ji 4#jf ,carbonic acid 7,,co7 ,water and organic matter #a4hh #a4ha ------------------- ,total #ii4he #ii4di ---------------------------------------- ------- ,the average of plant-food percentages in all these soils is quite low1 and at first sight there seems to be little choice between them4 ,yet two of them--,nos4 #fh and #hh1 from ,mississippi--are not only quite productive at the outset1 but also fairly durable4 ,this becomes measurably intelligible when it is known that both are of great depth1 and so well drained that roots can descend for many feet2 while the composition of the soil-material is almost identical for three or four feet4 ,on the other hand1 both ,nos4 #bjf and #bad are quite shallow1 being underlaid by sand almost devoid of plant-food at about two feet4 ,in addition1 both have extremely low percentages of phosphoric acid2 while the rest show near 4#aj of that ingredient1 an amount which1 as will be seen hereafter1 is considerably above the recognized limit of deficiency4 ,the two ,florida soils however bear only pine2 they are underlaid by almost clean sand at two or three feet1 and are therefore quickly exhausted4 ,it will also be noted that their lime-percentage is only about half of that of the two first-named ,mississippi soils1 both of which bear a strong growth of deciduous timber trees1 grape vines1 and other vegetation indicating the presence of lime carbonate4 ,it is noteworthy1 also1 that the popular classification of the two ,florida soils corresponds exactly with the differences in the percentages of plant-food2 those in the 8second-class0 soil being uniformly lower than those in the one designated as first-class4 ,this indicates1 again1 that as between soils of similar character and origin1 the production and durability are sensibly proportional to the plant-food percentages when the latter fall below a certain limit2 a point more fully illustrated farther on4 ,in the light of the above experiment and tables1 it becomes pertinent to consider what are the lowest percentage limits of each of the more important plant-food ingredients compatible with profitable production4 ,,limits ,,of ,,adequacy ,,of ,,the ,,several ,,plant-,,foods ,,in ,,virgin ,,soils4 ,it is obvious that the lower limits of adequacy of the critical plant-food ingredients are best ascertained in the case of virgin soils containing very small amounts of some one ingredient1 while fairly or fully supplied with the rest4 ,in such cases1 which are not at all infrequent1 the use of the deficient ingredient as a fertilizer should produce a very marked effect so soon as the first flush of production 7always noted in fresh soil7 is over4 ,this first productiveness may1 even in poor lands1 range from one to three years1 when there is a sudden decline4 ,lime a ,dominant ,factor4--,when we investigate the cases of such lands1 it soon becomes apparent that besides the low percentage of any one ingredient1 the proportions of others present require consideration4 ,among these1 lime in the form of carbonate stands foremost4 ,its presence exerts a dominant and beneficial influence in many respects1 as is readily apparent from the prompt change in vegetation whenever it is introduced into soils deficient in it4 ,in discussing the results of soil analysis1 its consideration is of first importance in forecasting correctly the adequacy or inadequacy of other soil ingredients 7see chapter #bj1 page #cgi74 ,for in general1 we find that lower percentages of potash1 phosphoric acid and nitrogen are adequate1 when a large proportion of lime carbonate is present4--,this has already been referred to in connection with the table of soils of low percentages1 given above4 ,in the interpretation of results obtained by analysis this point must always be kept in view2 and in the numerical statements made below1 it must be understood that they refer to virgin soils sufficiently supplied with lime to assure a constant excess of lime carbonate1 maintaining the conditions of nitrification and insuring the absence of acidity4 7,see chapter #i1 page #adf74 ,potash4--,in respect to potash1 the writer was led by his early investigations in the ,state of ,mississippi to conclude that less than one-fourth of one per cent 74#be7 of potash constituted a deficiency likely to call for early fertilization with potash salts2 while as much as 4#de of the same seemed to cause the land to respond but feebly to such fertilization4 ,he has not found it necessary to revise materially that early conclusion1 whether from his own work or from that of others4 ,within the last decade1 ,prof4 ,liebscher of ,gttingen#aai has arrived at this identical figure from analyses made of soils upon which he had conducted a seven-year series of fertilizer tests2 he having found that potash fertilization produced no sensible1 or at least no paying results on land giving that figure1 and otherwise well provided with plant-food4 ,the different 7lower7 figures given by ,schloesing1 ,risler and other ,french chemists in discussing the soils of ,france are doubtless due to the weak acid and short period of digestion employed in the analysis2 an unfortunate discrepancy of methods which precludes any direct comparison of results4 #aai ,untersuchungen ber die ,bestimmung des ,dngerbedrfnisses der ,ackerbden und ,kulturpflanzen1 von ,g4 ,liebscher2 ,journal fr ,landwirtschaft #dc 7#ahie71 ,nos4 #a #b1 pp4 #dh-baf4 ,these figures apply both to the arid and the humid regions in the temperate zones4 ,in the tropics we find very much lower percentages quoted as adequate2 thus in the laterite soils of ,india and ,samoa1 according to ,wohltmann1 in the soils of ,jamaica according to ,fawcett1 and in those of ,madagascar according to ,mntz and ,rousseaux4#abj ,there1 potash-percentages over 4#aj seem to be high1 and in ,madagascar some lands in fair production range as low as 4#ja4 ,the soil-extractions have however in these cases been made with a weaker acid than above specified1 so that some increase of the figures 7perhaps #cc to #ej7 have to be allowed for4 ,but even then there can be no question that a far less amount of potash1 as determined by acid-extraction1 is found sufficient for crop production in the tropics2 doubtless because of the very intense decomposing 78fallowing07 effect of the continuous heat and moisture1 tending also to a rapid decomposition of organic matter and a proportionally rapid formation of carbonic and nitric acids4 ,such soils are of course constantly kept in a leached condition1 as a result of the heavy and continuous rainfall4 #abj ,la ,valeur ,agricole des ,terres de ,madagascar4 ,ann4 de la ,science ,agronomique1 #b'me srie1 tome #a1 #aija4 ,phosphoric ,acid4--,as regards the lower limit of adequacy of phosphoric acid1 there is a remarkable agreement in the investigations made everywhere4 ,it was placed at 4#je by the writer as long ago as #ahfj1 as the result of investigations made in the ,state of ,mississippi2 and the same figure has since been arrived at independently by agricultural chemists in ,france1 ,russia1 ,germany and ,england4 ,the cause of this remarkable agreement is undoubtedly the readiness with which the phosphates that come under consideration at all for the nutrition of plants1 are dissolved by almost any acid treatment likely to be used in soil analysis4 ,almost the same agreement exists in regard to the 8adequacy0 of 4#a of ,p,o2 while all soils showing percentages between 4#a and 4#je are considered weak on this side1 and liable to need phosphate fertilization soon4 ,one-fourth of one per cent is an unusually high percentage in most countries2 4#cj and over is exceptional in non-ferruginous soils4 ,but as stated on a previous page1 a high percentage of lime carbonate may offset a smaller percentage of phosphoric acid1 apparently by bringing about greater availability2 and a similar effect seems to result from the presence of a large supply of humus4 ,on the other hand1 very large percentages of finely divided ferric hydrate may1 especially in the absence of lime carbonate1 render even large supplies of phosphoric acid inert and useless1 by the formation of the totally insoluble ferric phosphate4 ,aluminic hydrate probably acts in a similar manner4 ,the following table gives examples in point1 as regards ferric hydrate4 ,,hawaiian ,,soils ,,showing ,,high ,,contents ,,of ,,ferric ,,oxid4 7,rept4 ,cal4 ,exp4 ,sta4 #ahid-e1 page #bg47 ,oahu4 ,hawaii4 ---------------------------------------- ------------------------ ,,number ,,of ,,sample4 ,no4 #ba4,no4 #bb4,no4 #bd4,no4 #bf4,no4 #bg4 ---------------------------------------- ------------------------ ,coarse ,materials4 #j4ee #b4jj #b4ej #d4jj #c4jj #e4jj ,fine ,earth #ih4jj #ig4ej #if4jj #ig4jj #ie4jj ,,chemical ,,analysis ,,of ,,fine ,,earth4 ,insoluble matter #ae4hd #ad4di #bf4ii #bh4ff #ba4jg ,soluble ,silica #ad4jg #cj4cg #aj4bf #g4ce #b4fh ,potash 7,k,o7 4#de 4#bf 4#dj 4#fa 4#dd ,soda 7,na,o7 4#ad 4#jh 4#bf 4#ag 4#be ,lime 7,ca,o7 4#bf #a4jd 4#eb 4#fh 4#bh ,magnesia 7,mg,o7 4#fe 4#hj 4#if #a4jd 4#fj ,br4 ox4 of ,manganese 7,mn,o7 4#je 4#jc 4#ba 4#bj 4#jg ,peroxid of ,iron 7,fe,o7 #ci4je #ai4fh #ai4aj #ah4bc #cj4aj ,alumina 7,al,o7 #ad4fa #ah4bi #ba4da #bj4ah #ad4ch ,phosphoric acid 7,p,o7 4#ai 4#cb 4#fd 4#gj 4#ig ,sulfuric acid 7,,so7 4#jc 4#ji 4#cb 4#ba 4#bi ,carbonic acid 7,,co7 ,water and organic matter #ad4ah #ad4ei #ah4fj #ba4fe #bh4fj ----------------------------------- ,total #ii4eb #ajj4jd #ii4fg #ii4fa #ii4gc ,humus #c4ce #c4bd #d4hd #e4dc #i4ie 8 ,ash #c4ab #b4bb #b4gf #c4ef #f4gj 8 ,nitrogen1 p4c4 in ,humus #c4cj #i4hjj #b4hjj #c4ajj #a4ga 8 8 1 p4c4 in soil 4#aab 4#cad 4#acd 4#afh 4#ag ,phosph4 acid in humus ash 4#aaj 4#aff 4#ehj 4#ejj ,soluble in #b ,citric acid 4#jjd 4#jbj 4#jce 4#jcg 4#jbe in ,nitric acid1 #a4bj sp4 g4 4#aij 4#cbj 4#fdj 4#gjj 4#igj in ,chlorhydric acid 7#a4aae sp4g47 4#dcj 4#cej #a4fjj #a4bhj ,hygroscopic moisture #ae;,c4 #ah4ej #ba4be #bc4jg #bc4ad #bc4ha ---------------------------------------- ------------------------ ,unavailability of ,ferric ,phosphate4--,it will be noted that in the soils from ,oahu with an overwhelming amount of ferric oxid 7mostly in the form of hydrate or rust7 the citric acid has taken up only an insignificant amount of phosphoric acid2 nitric acid took up #dj to #ej times as much1 and chlorhydric doubled even this4 ,in the much less ferruginous ,hawaiian soils1 though containing more alumina1 the citric acid extracted nearly ten times as much2 proving that it is chiefly ferric oxid1 and not the alumina as has been supposed1 that causes the insolubility of phosphoric acid in soils and doubtless also in fertilizers4 ,the very unusually high content of phosphoric acid in the ,hawaiian soils1 exceeding all others on record1 so far as known to the writer1 emphasize the effects of ferric hydrate upon soluble phosphates2 while the fact that these very soils are greatly benefited by the use of phosphate fertilizers1 proves that the ,dyer 7citric acid7 method for the determination of available phosphoric acid which in soils ,nos4 #ba to #bf yielded results largely in excess of the established limit in ,european soils1 cannot be successfully applied to these highly ferruginous soils4 ,it should also be noted that the amounts of phosphoric acid found in the humus extracted by the ,grandeau method is in the first two ,hawaiian soils over ten times the amount extracted by citric acid1 but that while they rise and fall together1 no definite quantitative ratio exists between the two4 ,it is obvious that in such soils1 fertilization with water-soluble phosphates would be likely to result in the quick partial withdrawal of the same from useful action1 and that any excess not promptly taken up by the crop1 is likely to become inert and useless4 ,it will evidently be desirable to use the phosphates in the form of bone meal or basic slag 7,thomas ,phosphate71 which because of their difficult solubility will be acted upon but very slowly1 if at all1 by the ferric and aluminic hydrates4 ,nitrogen4--,in determining the nitrogen-content of the soil1 a great variety of methods has been followed4 ,some include all that can be obtained by the combustion of the organic matters of soil and from the nitrates present in the same2 while others1 the writer among the number1 believe that the mainly important source of nitrogen to the plant being the nitrification of the humus-nitrogen1 the determination of the humus by the method of ,grandeau1 and of the nitrogen contained in it1 should be the standard2 the unhumified vegetable matter being of no definitely ascertainable value1 and the nitrates varying from day to day and being liable to be lost by leaching at any time2 therefore forming no permanent feature of the soil4 ,considering the variety of methods1 the unanimity with which about one-tenth of one per cent 74#aj7 has been assumed as the ordinarily adequate percentage is remarkable4 ,in view of the extremely variable amount of nitrogen in the humus 7ranging from #a4g to nearly #bb71 the amount of the latter cannot1 of course1 afford even an approximation to the nitrogen-content2 except that as in the humid region1 the nitrogen-percentage is not known to exceed about #e or #e4e1 an approximate estimate can be made on that basis4 ,in the arid region1 according to location1 the nitrogen-percentage may be from three to six times greater for a similar amount of humus4 7,see chap4 #h4 p4 #ace74 ,in the writer's experience1 a nitrogen-percentage of 4#a in the arid region is a very satisfactory figure1 indicating that the need of nitrogen-fertilization is not likely to arise for a number of years4 ,nitrification of the ,organic ,matter of the ,soil4--,in order to test the question whether or not the nitrogen of the unhumified debris existing in surface soils is directly nitrifiable1 the writer selected a soil which in its natural condition sustains intense nitrification1 so that at some points it contains as much as #abjj pounds of sodic nitrate per acre4 ,the composition of this soil1 representing the land of the 8ten-acre tract0 of the southern ,california substation1 is as follows3 ,,soil ,,from 8,,ten-,,acre ,,tract10 ,,southern ,,california ,,sub-,,station1 ,,no4 #abhd4 ,coarse ,materials #j4ee #a4jj ,fine ,earth #ii4jj ------ #ajj4jj ,,chemical ,,analysis ,,of ,,fine ,,earth4 ,insoluble matter #fb4fb #gj4ib ,soluble silica #h4cj ,potash 7,k,o7 4#ie ,soda 7,na,o7 4#ej ,lime 7,ca,o7 #e4jg ,magnesia 7,mg,o7 4#hd ,br4 ox4 of ,manganese 7,mn,o7 4#jf ,peroxid of ,iron 7,fe,o7 #f4dc ,alumina 7,al,o7 #c4hh ,phosphoric acid 7,p,o7 4#ba ,sulfuric acid 7,,so7 4#jf ,carbonic acid 7,,co7 #c4ff ,water and organic matter #f4jb ----- ,total #ii4gj ,water-soluble matter1 per cent4 4#acg ,sodic nitrate1 per cent4 4#jbj ,humus #a4ii 8 ,ash #a4ac 8 ,nitrogen1 per cent4 in ,humus #aj4cj 8 8 1 per cent4 in soil 4#bjc ,total ,nitrogen in soil 4#ccj 8 8 in unhumified matter 4#abg ,available ,potash citric 4#jc ,available ,phosphoric acid method ,hygroscopic ,moisture absorbed at #ae ,c4 #e4ha ,it will be noticed that this is a rather strongly calcareous soil1 7nearly #i of calcic carbonate71 slightly impregnated with alkali1 of which about one-ninth is saltpeter4 ,one portion of this soil was thoroughly leached with distilled water until not a trace of nitrates could be detected in the leachings4 ,another portion was treated for the removal of humus according to the ,grandeau method 7see chapter #h1 page #acb72 the extracted soil showed under the microscope an abundance of vegetable debris1 some slightly browned as from incipient humification4 ,the calcic and magnesic carbonates withdrawn in the humus-extraction were then restored to the soil in the form of finely divided precipitates and thoroughly mixed in1 first in the dry and then in the wet condition2 the extracted soil being repeatedly wetted with turbid water from the leached soil1 in order to replace and reinfect it with the nitrifying bacteria4 ,both soils were then spread out in flat glass dishes and placed in a wooden box containing also a similar flat dish with distilled water1 upon which played the draught from the inlet pipe opening into the outer air1 with outlet-holes in the cover at the opposite end2 thus keeping the air within fairly moist4 ,in addition1 the soils themselves were moistened with distilled water every three days and restored to a loose condition by stirring4 ,the whole was placed so as to maintain1 during the greater part of the #bd hours1 a temperature of from #cj to #ce degrees ,c4 ,at intervals the samples of both soils were leached and color-titrated for their nitrate content by the picric-acid test4 ,the results1 calculated as sodic nitrate1 during two years were as follows3 ,nitrate formed during,four months4,twelve months4,two years4 ---------------------------------------- ----------------- ,leached natural soil 4#jab 4#jdbj 4#jfa ,extracted soil ,none4 4#jjcj 4#jjdb ---------------------------------------- ----------------- ,it will be noted that in the course of four months1 nitrification had not sensibly set in the extracted soil2 while in the leached natural soil the nitrate-content had reached to three-fifths the amount originally present1 and in the course of a year the nitrate-content of the latter was more than double that of the original 7unleached7 soil2 while that in the extracted soil had only reached one-seventh of the same4 ,at the end of two years we find a still farther increase of nitric nitrogen in both1 the ratio between the two remaining about the same 7#a3ad74 ,at the same time the ratio of increase attained at first had materially diminished in the water-leached soil1 probably on account of the accumulation of the niter itself4 ,it thus appears that although the nitrogen of the unhumified organic matter constituted about #dj of the total in the original soil1 it would during the entire year have contributed only to an insignificant extent to the available nitrate-supply2 while the fully humified 8matire noire0 contributed fourteen times as much4 ,during the ordinary growing-season of four or five months the unhumified organic matter would have yielded practically nothing to the crop4 ,functions of the unhumified ,vegetable ,matter4--,the chief utility of the unhumified matter in the soil consists of course in its gradual conversion into true humus1 in the course of which it evolves carbonic gas to act on the soil minerals2 while at the same time it helps to render the soil more porous and thus facilitates the action of the aerobic bacteria1 for which it serves as food4 ,hence the addition of vegetable matter to soils not already too 8light0 is always advantageous1 so long as it does not introduce injurious1 non-humifiable ingredients1 like turpentine in the sawdust of resinous pines4 ,but it is always advisable to first use such matter as litter for stock1 in order to better prepare it for the processes of humification1 under the influence of ammoniacal fermentation1 such as occurs in the decay of green plants or animal matter4 ,a portion of the ash ingredients also is quickly utilized by solution in the soil-water4 ,matire ,noire the ,only ,guide4--,according to these results it is clear that in order to gain any tangible indications with respect to crop-bearing1 it is the nitrogen in the humus proper1 the matire noire only1 that should serve as the basis2 and that as a current source of nitrogen to the plant1 the unhumified matter is hardly entitled to more consideration than the 8insoluble silicates40 ,for1 the favorable conditions for nitrification under which the above experiment was conducted1 will very rarely be even approached under field conditions4 ,what are the ,adequate ,nitrogen ,percentages in the ,humus8--,the nitrification of the matire noire being1 apparently1 the main source of plant-nutrition with that element under ordinary conditions1 the question naturally arises as to what may be considered an adequate nitrogen-content of that substance1 so as to permit a full supply of nitrates to the crop4 ,the data extant on this subject are rather scanty1 and thus far have all been obtained at the ,california ,experiment ,station4#aba ,but they seem to be very cogent in proving that the growth of crops removed from the soil causes a rapid depletion of the nitrogen in the humus-substance1 and that so soon as the nitrogen-percentage in the same falls below a certain point1 the soil becomes 8nitrogen-hungry20 so that the application of nitrogenous fertilizers is needed and is very effective4 ,the data in the table below1 as well as the figure of a culture experiment 7,no4 #eb below71 illustrate this point4 ,,adequacy ,,and ,,inadequacy ,,of ,,nitrogen ,,contents ,,of ,,humus4 ,collection,kind of ,locality4 ,per cent4,per cent4 ,per cent4 ,number4 ,soil4 ,humus in ,nitrogen ,nitrogen ,soil4 in ,humus4in ,soil4 #abb ---------------------------------------- ----------------------- #f ,black ,near ,stockton1 ,san ,adobe4 ,joaquin ,co41 ,cal4 #a4je #ah4ff 4#aif ---------------------------------------- ----------------------- #afgi 8 ,virgin ,soil1 ,university ,grounds1 ,berkeley #a4bj #ah4eh 4#bjc ---------------------------------------- ----------------------- #ahdb 8 ,ramie plot1 ,univ4 ,grounds1 #aj years cultivated #a4hj #d4ag 4#jge ---------------------------------------- ----------------------- #ahda 8 ,grass plot1 ,univ4 ,grounds1 #aj years cultivated #a4fe #c4dj 4#jef ---------------------------------------- ----------------------- #bi ,dark ,sugar-cane land1 loam4 ,maui1 ,h4 ,t4 #aj4ij #c4ae 4#cdg ---------------------------------------- ----------------------- #bg ,dark ,guava-land hills1 loam4 near ,hilo1 ,hawaii #i4ie #a4ga 4#agj ,island ---------------------------------------- ----------------------- #aba ,the ,supply of ,soil ,nitrogen1 ,rep4 ,cal4 ,expt4 ,station1 #ahib-ic1 page #fh2 ibid41 #ahid-ie1 page #bh2 ,the ,recognition of ,nitrogen ,hungriness in ,soils1 in ,bull4 #dg1 ,div4 of ,chemistry1 ,u4,s4 ,department of ,agriculture1 #ahie2 ,landw4 ,presse1 ,no4 #ec1 ,july #ahhe4 ,see also for detailed data chapter #h1 page #ace4 #abb ,calculated upon the true humus substance 7matire noire71 not by determining total 7incl4 unhumified7 nitrogen in the soil4 ,nos4 #f and #afgi show the usual humus-and nitrogen-percentages in the 8black adobe0 or 8prairie0 soils of ,california4 ,nos4 #ahdb and #ahda represent the same soil as #afgi1 upon which1 however1 ramie and ray grass had respectively been growing1 without fertilization1 for about ten years2 showing that while the humus-content of the soil has increased1 the nitrogen-content of the humus has decreased in the case of ramie by #gb4gh1 in that of the grass by #gf4gh2 reducing the land to figures commonly found in the humid region4 ,in the case of the ramie1 the partial return through the leaves has resulted in a higher humus-content1 together with higher nitrogen-percentage1 than in the case of the grass1 which in the several cuttings annually made1 caused a greater depletion in nitrogen and a smaller accession of humus4 ,the grass was very weak in its growth and partially dying out4 ,no4 #bi1 the sugar-cane land from ,maui1 was still in fair production1 but beginning to weaken as against its first production4 ,no4 #bg1 the guava land from ,hawaii1 originally bore a luxuriant cover of wild guava1 but after bearing one fair crop of seed-cane and one of ratoons1 the cane planted on it 8spindled up0 and died so soon as the seed-cane planted was exhausted4 ,both the island soils1 originally derived from the weathering of the black basaltic lavas of the region1 were well supplied with mineral plant-food 7see above1 page #cef71 and the humus-content in both was exceptionally high2 and neither was in an acid condition4 ,the difference in their nitrogen-content1 both in the totals and in the humus itself1 suggested that notwithstanding the relatively high total of nitrogen in ,no4 #bg1 it might be nitrogen-hungry1 in view of the low percentage of the nitrogen in the humus4 ,illustration3 ,,fig4 #ei4--;,growth of ,wheat on ,guava ,soil from ,hawaii ,island4 ,confirmatory ,experiment4--,a pot-culture with wheat1 the results of which are shown in the figure below1 fully confirm this suspicion4 ,one kilogram of soil was used in each of two pots1 one being fertilized with half a gram of ,chile saltpeter4 ,the experiment could not be carried to full completion on account of the overwhelming invasion of mildew2 but the figures speak for themselves4 ,moreover1 a field trial made on the island with saltpeter1 in pursuance of the writer's recommendation1 resulted in a luxuriant growth of the cane4 ,data for ,nitrogen-adequacy4--,it appears from the facts shown above1 that for the growth of grasses a nitrogen-percentage in the humus of #a4g is wholly inadequate1 no matter how much humus may be present4 ,a percentage of #c4ae in the ,maui soil1 ,no4 #bi1 containing nearly #aa of humus1 gave only a fair crop of sugar-cane2 on the ,berkeley grass plot1 with #c4dj and only #a4fe of total humus1 the ray grass was barely maintaining life4 ,the ramie1 with #d4ag of nitrogen in the soil-humus1 was still doing fairly well4 ,it is doubtless impossible to give one and the same absolute figure for nitrogen-deficiency for all plants and soils4 ,where the conditions of nitrification are favorable1 as in the presence of much of the earth carbonates1 a smaller percentage may suffice for the same plants that elsewhere suffer2 and it is highly probable that different minima will be found for plants of different relationship and root-habits4 ,but there is every reason to believe that in the nitrogen-percentage of soil-humus1 considered in connection with other chemical and physical conditions and soil derivations1 we have a means of ascertaining the needs of plants with respect to nitrogen-fertilization1 if proper study be given to the subject4 ,broadly speaking1 it appears to be necessary to keep the nitrogen-percentage of soil-humus near #d to insure satisfactory production4 ,it having been suggested that the frequent and disastrous crop failures on the noted tchernozem or black-earth soils of ,russia might be due in part at least to nitrogen-depletion of the humus1 the writer obtained through the courtesy of ,prof4 ,p4 ,kossovitch of ,st4 ,petersburg soil samples from the center of the ,black-earth region1 both cultivated and uncultivated4 ,these samples are in appearance exactly like some of the dark alluvial soils of ,louisiana and ,california1 and approach them very nearly in the essentials of composition1 as will be seen from the table below3 ,,analyses ,,of ,,black ,,soils1 ,tchernozem ,alluvial 7,russia47 ,black clay lands4 ----------------------------------- ,louisiana,california ,no4 #bdj4 ,no4 #aafg4 ,virgin,cultivated------------------- ,back-land,black-land ,houma4 ,tulare4 ---------------------------------------- ------------------------ ,,chemical ,,analysis ,,of ,,fine ,,earth4 7,no coarse material in soils47 ,insoluble matter #dh4ch #ee4ji #ce4dh #fb4dc ,soluble silica #ac4ba #ab4bh #bj4gf #af4ii ,potash 7,k,o7 4#gb 4#eb #a4jc #a4ji ,soda 7,na,o7 4#bj 4#ac 4#ac 4#gg ,lime 7,ca,o7 #a4ea #a4ca 4#gb #a4df ,magnesia 7,mg,o7 4#gc 4#ge 4#hh #a4dd ,br4 ox4 of ,manganese 7,mn,o7 4#je 4#jc 4#ja 4#jf ,peroxid of ,iron 7,fe,o7 #g4ab #d4hj #g4aj #d4ih ,alumina 7,al,o7 #e4bb #d4gc #ae4de #f4hg ,phosphoric acid 7,p,o7 4#ad 4#ac 4#ae 4#ab ,sulfuric acid 7,,so7 4#jg 4#jh 4#be 4#jb ,carbonic acid 7,,co7 ,water and organic matter #bb4gh #ai4id #ah4eb ,total #ajj4ac #ii4gi #ajj4dh #ajj4ei ,humus #e4aa #e4ed #e4jg #a4cc 8 ,ash #a4hj #a4dj 4#ia 4#cf 8 ,nitrogen1 per cent4 in ,humus #d4fc #d4bb 8 8 per cent4 in soil 4#bg 4#bd ,available ,potash 7citric acid method7 4#jad 4#jaj ,available ,phosph4 acid 4#jaa 4#jjh 4#jh 4#ja 7citric acid method7 ,hygroscopic ,moisture #ab4jg #ah4hb #e4ch absorbed at #ag;,c #ac;,c #ae;,c ---------------------------------------- ------------------------ ,it will be seen that the ,russian soil is of high fertility according to the standards given above1 and that the nitrogen-content of the abundant humus is amply within the limits of adequacy suggested by the experience in ,california and ,hawaii4 ,the humus-content of the arid ,california soils is characteristically low as compared with the ,russian tchernozem as well as with the ,houma backland of humid ,louisiana2 but its nitrogen-content is doubtless at least three times that of the latter1 as is that of the humus of similar lands in which it has been determined4 ,,influence ,,of ,,lime ,,upon ,,soil ,,fertility4 ,assuming as substantially correct the numerical data given above in respect to the three leading ingredients of plant-food--phosphoric acid1 potash and nitrogen1--the dominant role of lime in soil fertility1 already mentioned1 requires some farther illustration and discussion4 8,a ,lime ,country is a ,rich ,country40--,the instant change of vegetation when we pass from a non-calcareous region to one having calcareous soils1 has already been alluded to4 7,see this chapter1 p4 #ced74 ,but it is not necessary to be a botanist to see the change in the prosperity of the farming population as one enters a lime district4 ,the single log-cabin with1 probably1 a wooden barrel terminating the mud-plastered chimney1 is replaced1 first by double log-houses1 then by frame1 and farther on by brick buildings1 with the other unmistakable evidences of prosperity4 ,thus this is seen in passing from the mountain region of ,kentucky into the 8blue-grass0 country1 which is throughout underlaid by calcareous formations2 and thus1 likewise1 in crossing the strike of the formations of ,alabama1 ,mississippi and ,louisiana1 or any other region where underlying calcareous formations have contributed to the formation of the soils1 as compared with some adjacent district where this is not the case4 ,the calcareous loess areas bordering on the ,mississippi river and some of its chief tributaries1 are conspicuous cases in point1 as are also the prairies of ,illinois and ,indiana4 ,effects of ,high ,lime-content in ,soils4--,the table below illustrates the fact that in the presence of high lime-percentages1 relatively low percentages of phosphoric acid and potash may nevertheless prove adequate2 while the same1 or even higher amounts1 in the absence of satisfactory lime-percentages prove insufficient for good production4#abc #abc ,this statement appears contradictory of the observations of ,schloesing upon the solubility of phosphoric acid in presence of lime carbonate 7,am4 ,sci4 ,agron41 tome #a1 #ahii71 but the natural conditions seem to justify fully the above conclusion4 ,,soils ,,showing ,,low ,,phosphoric ,,acid ,,percentage4 ,,high ,,lime4 ------------------------------------ ,mississippi,louisiana ,california ----------------------------------- ,kemper ,vernon ,yuba ,amador ,county ,county ,county ,county ---------------------------------------- ----------------------- ,number of ,sample4 #aci #aga #dii #aaac ---------------------------------------- ----------------------- ,chemical ,analysis of ,slate ,fine ,earth4 ,soil ---------------------------------------- ----------------------- ,insoluble matter #ec4ai #gh4gi #di4if #fg4jh #gd4bi #fd4ib ,soluble silica #ba4aj #c4hj #ad4if ---------------------------------------- ----------------------- ,potash 7,k,o7 4#gj 4#cc 4#be #a4dh ,soda 7,na,o7 4#ad 4#jf 4#jd 4#dc ,lime 7,ca,o7 #a4cg #a4dj #a4jb 4#fj ,magnesia 7,mg,o7 #a4jj 4#gd 4#dj #b4ba ,br4 ox4 of ,manganese 7,mn,o7 4#be 4#ae 4#jb 4#je ,peroxid of ,iron 7,fe,o7 #f4ge #d4eb #e4ha #aa4eb ,alumina 7,al,o7 #ac4jg #aa4cf #f4bh #ab4ca ,phosphoric acid 7,p,o7 4#jc 4#je 4#jd 4#je ,sulfuric acid 7,,so7 4#jh 4#ab 4#jb 4#jb ,carbonic acid 7,,co7 ,water and organic matter #i4de #g4bg #c4fd #f4fc ----------------------------------- ,total #ii4ia #ajj4bi #ajj4aiajj4bb ----------------------------------- ,hygroscopic ,moisture #aa4de #ah4aa #d4hj #e4gd absorbed at ,c #h4j #be4e #ae4j #ae4j ---------------------------------------- ----------------------- ,,low ,,lime4 -------------------------------------- ,mississippi ,california ------------------------------------ ,chickasaw,carroll ,shasta ,humboldt ,county ,county ,county ,county ---------------------------------------- ------------------------ ,number of ,sample4 #afd #dh #eei #bjg ---------------------------------------- ------------------------ ,chemical ,analysis of ,fine ,earth4 ---------------------------------------- ------------------------ ,insoluble matter #ic4fb #gf4bg #fe4ce #id4ih #hi4ci #hj4ch #gb4bd ,soluble silica #a4cf #d4aj #f4ij ---------------------------------------- ------------------------ ,potash 7,k,o7 4#ji 4#ai 4#ej #a4ac ,soda 7,na,o7 4#jg 4#jh 4#jd 4#bh ,lime 7,ca,o7 4#jg 4#jh 4#aj 4#aa ,magnesia 7,mg,o7 4#ac 4#jg 4#dj #c4cc ,br4 ox4 of ,manganese 7,mn,o7 4#jb 4#ab 4#ja 4#ab ,peroxid of ,iron 7,fe,o7 #a4ji #a4ba #f4fg #f4ii ,alumina 7,al,o7 #a4dg #d4cg #h4dh #aj4bd ,phosphoric acid 7,p,o7 4#jc 4#je 4#jd 4#ag ,sulfuric acid 7,,so7 4#ja 4#je 4#ja 4#jb ,carbonic acid 7,,co7 ,water and organic matter #b4jj #d4ji #c4ig #e4fc ------------------------------------ ,total #ii4id #ii4gj #ajj4fb #ajj4bd ------------------------------------ ,hygroscopic ,moisture #a4hj #d4ff #e4je #g4hg absorbed at ,c #aa4j #aa4j #ag4j #ac4j ---------------------------------------- ------------------------ ,nos4 #aci and #aga are heavy black prairie soils of high productive capacity1 whose production had1 at the time of sampling1 lasted almost undiminished for over twenty years4 ,nearly the same is true of the two ,california soils1 ,nos4 #dii and #aaac2 which1 however1 are ferruginous loams of only moderate clay-content4 ,in all1 the percentage of phosphoric acid shown by the analysis is at or below the recognized limit of deficiency1 while the lime-content of all is as high as is required for the welfare of any soil1 however constituted4 ,the potash-percentage also is low in all except the 8red foothill soil10 ,no4 #aaac4 ,passing to the soils of low lime-content1 we find the two ,mississippi soils1 poor in both potash1 lime and phosphoric acid1 so low in production as to be wholly unprofitable in cultivation without previous fertilization2 ,no4 #eei1 from ,california1 produced two fair crops of barley and then no more4 ,no4 #bjg1 is the soil of ,eel river bottom1 ,california2 profusely productive at first1 by virtue of its high content of both potash and phosphoric acid2 but 8giving out0 under a few years' culture of clover or alfalfa 7which draw heavily upon lime71 and quickly restored to productiveness under the influence of dressings of quicklime4 ,in this case the soil had become acid1 a condition which always militates against the success of culture plants1 and more especially against those of the leguminous relationship4 ,what are ,adequate ,lime ,percentages8--,we have in the presence or absence of the natural vegetation peculiar to calcareous soils 78calciphile07 an excellent index of the presence or absence of such amounts of lime carbonate as fulfil the conditions of its beneficial effects4 ,lists of such plants for the ,united ,states are given farther on2 they agree almost throughout with such plants as are everywhere recognized by ,american farmers as indicating productive soils4 ,all soils bearing such vegetation show with red litmus paper1 when wetted1 a neutral reaction at first1 which after the lapse of twenty or thirty minutes turns to a blue alkaline one2 such as is given under the same conditions by the carbonates of lime and magnesia4 ,but the reverse is not necessarily true2 for we occasionally find soils containing considerable amounts of lime carbonate that yet fail to bear lime vegetation4 ,this is the case of extremely heavy clay soils1 as exemplified in the table below in the case of the last three soils2 while the first1 ,no4 #bbj1 exemplifies a case where although potash is exceptionally high1 only scrubby oak growth is produced in presence of an amount of lime that in sandy lands would show profuse lime growth4 ,,table ,,illustrating ,,the ,,need ,,of ,,high ,,lime-,,percentages ,,in ,,heavy ,,clay ,,soils4 ,mississippi4 ,california4 ------------------------------------ ,flatwoods ,hog- ,ridge ,yellow ,pontotoc wallow ,prairie1 ridge1 ,co4 ,jasper,smith ,co4,alameda ,co4 ,co4 ---------------------------------------- ------------------------ ,no4 ,sample4 #bcj #bdb #bjc #d ---------------------------------------- ------------------------ ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ------------------------ ,insoluble matter #gg4he #gf4gf #ea4ge #hf4jj ,soluble silica ---------------------------------------- ------------------------ ,potash 7,k,o7 4#ge 4#ec 4#ec 4#ai ,soda 7,na,o7 4#aa 4#ai 4#bb 4#ae ,lime 7,ca,o7 4#ah 4#db 4#dh 4#dh ,magnesia 7,mg,o7 4#hc 4#fg #a4ja 4#de ,br4 ox4 of ,manganese 7,mn,o7 4#ag 4#ef 4#aj 4#jd ,peroxid of ,iron 7,fe,o7 #e4ij #d4ab #bc4gi #d4ja ,alumina 7,al,o7 #aj4cj #aj4jf #aj4he #e4ec ,phosphoric acid 7,p,o7 4#je 4#jf 4#ae 4#jf ,sulfuric acid 7,,so7 4#jc 4#jf 4#jb 4#jb ,carbonic acid 7,,co7 ,water and organic matter #c4fi #e4gc #aa4ci #d4je ------------------------------------ ,total #ii4hf #ii4ag #ajj4bi #ajj4ii ------------------------------------ ,hygroscopic ,moisture #i4c #f4h #ai4g absorbed at ,c #bb4j air-dry #ag4j ---------------------------------------- ------------------------- ,all of the soils in this table are heavy clays1 very difficult to till2 in all1 the lime-percentage falls below 4#e2 and none bear any lime vegetation1 the ,mississippi soils having a stunted growth of black jack and post oaks1 such as is universally known to indicate soils too poor for profitable cultivation4 ,the ,california soil bears stunted live-oak 7,q4 agrifolia72 but not being as heavy as its brethren from ,mississippi1 though unthrifty1 is more readily improved4 ,comparison with the two first sandy soils in the table on p4 #ceb shows1 that with plant-food percentages equal to1 or even much below those here shown1 not only was vigorous lime growth present1 but crop-production was good and even high4 ,we are thus led to the conclusion that the greater the clay percentage in a soil1 the more lime carbonate it must contain in order to possess the advantages of a calcareous soil2 and that while in sandy lands lime growth may follow the presence of only 4#aj of lime1 in heavy clay soils not less than about 4#f should be present to bring about the same result4 ,this is apparent to the eye in that the dark-tinted humus characteristic of truly calcareous lands1 does not appear in clay soils until the lime-percentages rise to nearly #a2 while in sandy lands a much smaller amount 7say 4#b7 will produce this effect4 ,european ,standards4--,it is of interest to consider1 in connection with preceding discussions1 the estimates given by ,maercker of ,halle1 of the practical value of soils corresponding to chemical composition as ascertained by analysis with strong acids1 substantially in accordance with the methods adopted by the writer4 ,,practical ,,rating ,,of ,,soils ,,by ,,plant-,,food ,,percentages ,,according ,,to ,,prof4 ,,maercker1 ,,halle ,,station1 ,,germany4 ,lime4 ,grade of ,soil4 ,potash4 ,phosphoric------------------- ,acid4 ,clay ,sandy ,soil4 ,soil4 ---------------------------------------- -------------------- ,poor ,below #j4je;,below #j4je;,below 4#aj;,below 4#je ,medium #j4je-j4ae 4#je - 4#aj 4#aj- 4#be 4#aj-4ae ,normal #j4ae-j4be 4#aj - 4#ae 4#be- 4#ej 4#ae-4bj ,good #j4be-j4dj 4#ae - 4#be 4#ej-a4jj 4#bj-4cj ,rich ,above #j4dj ,above 4#be;,above #a4jj;,above 4#cj ,av'age for ,california #j4gj #j4jh #a4jh 8 8 ,arid ,reg4 4#gc 4#ab #a4cf 8 8 ,humid ,reg4 4#bb 4#aa 4#aa ---------------------------------------- --------------------- ,grade of ,soil4 ,total ,humus ,nitrogen4 ,nitrogen4 ---------------------------------------- - ,poor ,below 4#je ,medium 4#je-4aj ,normal 4#aj-4ae ,good 4#ae-4be ,rich ,above 4#be ,av'age for ,california 4#ajb 8 8 ,arid ,reg4 4#aa 787 8 8 ,humid ,reg4 4#ab 4#aff ---------------------------------------- - ,it will be observed that according to ,maercker's valuation1 the average ,california soil is 8rich0 in potash and lime1 but only 8medium0 as regards its contents of phosphoric acid and nitrogen4 ,in this respect1 and almost throughout1 ,maercker's ratings are in remarkable agreement with those made by the writer as far back as #ahfj4abd ,it also appears that ,maercker's figures for 8normal0 soils correspond to those of the ,american humid regions2 the 8arid0 figures for potash and lime being 8abnormally0 high4 #abd ,see discussions of analyses of ,mississippi soils in the ,report on the ,agriculture and ,geology of ,mississippi1 #ahfj2 same in ,rep4 ,on ,cotton ,production1 ,tenth ,census1 #ahhj1 ,vol4 #e2 also ,appendix to the ,report on the ,experiment ,stations of the ,university of ,california1 #ahij1 p4 #afc4 ,unfortunately neither ,maercker's method of preparing the soil extract1 nor his ratings as given in the table1 are accepted by all soil chemists even in ,germany4 ,as will be seen by reference to ,wohltmann's work on the soils of ,samoa and ,kamerun 7chap4 #ba1 p4 #djd71 his methods and numerical estimates differ widely from those given by ,maercker1 and also from those adopted by the ,prussian soil surveys4 ,reference to the analyses of the soils of ,madagascar by ,mntz and ,rousseaux1 given in the same chapter1 page #djf1 shows still another different method1 although as it happens their numerical estimates do not differ very widely from those of ,wohltmann4 ,in both cases1 a special1 more incisive extraction is made for the determination of potash4 ,why the same more energetic action is not used for the other ingredients also1 is not stated1 and is obscure4 ,fortunately1 in all cases the action is at least sufficiently strong to secure the dissolution of all the lime existing in the form of carbonate1 and of all1 or nearly all1 the phosphoric acid not securely locked up as ferric phosphate2 the latter being inert1 is of no special interest 7see ,analyses of ,hawaiian ,soils1 this chapter1 page #bef74 ,,chapter ,,xx4 ,,soils ,,of ,,the ,,arid ,,and ,,humid#abe ,,regions4 ,composition of ,good ,medium ,soils4--,in the preceding tables examples have been given of rather extreme types of soils1 both rich and poor throughout1 and also of such as are deficient in one or several of the important ingredients4 ,in the table below are given the analyses of some of the good average farming lands2 uplands of several states1 both of the humid and arid regions4 ,in the former1 the representative timber trees of such lands are the black1 red1 white and 7less characteristically7 the post1 black-jack1 ,spanish1 overcup and locally some other oaks2 grading higher in proportion to the presence of more or less hickory1 and lower as the latter is replaced by pine4 ,in the states south of ,ohio1 the 8oak and hickory uplands0 are what the farmer usually looks for1 outside of the valleys or bottoms4 #abe ,in the discussion in this chapter the 8humid region0 referred to is always that of the temperate zones1 unless expressly otherwise stated4 ,the most humid region of all--the tropics--is treated under a special head4 ,criteria of ,lands of the ,two ,regions4--,in the country west of the ,rocky ,mountains1 the timber1 while locally very characteristic1 cannot be as broadly used as a criterion1 partly on account of its scarcity1 partly because the dominant factor in the growth of trees is moisture1 which is measurably independent of chemical soil-composition4 ,the latter1 moreover1 on account of climatic conditions1 already alluded to 7chapter #af71 does not vary as materially in the arid as the humid region1 on account of the almost universal presence of larger proportions of lime carbonate2 the variations of which in the humid region govern largely the vegetative changes4 ,for we there find the timber growth of the lowlands ascending into the uplands so soon as the latter becomes decidedly calcareous2 as is abundantly exemplified in the loess or 8bluff0 formations bordering the ,mississippi1 ,ohio1 and ,missouri rivers1 where the black walnut1 tulip tree1 ash1 honey-locust1 together with the lowland oaks1 hickories and cane usually characterizing the stream bottoms1 grow abundantly and with luxuriant development on the adjoining steep hill country as well 7see below1 chapters #bd1 #be74 ,,upland ,,soils ,,of ,,humid ,,region4 ,,oak ,,uplands ,,with ,,hickory ,,and ,,walnut4 ---------------------------------------- ------------------------ ,state4 ,tennessee4 ,mississippi4 ,alabama4,georgia4 ---------------------------------------- ----------------------- ,county4 ,rutherford,pontotoc,benton,cherokee ,polk ---------------------------------------- ----------------------- ,number of ,sample4 #g #bbf #baf #aaj #ejb ---------------------------------------- ----------------------- ,,analysis ,,of ,,fine ,,earth4 ,insoluble matter #ge4ce #hc4bg #gh4gc #gb4cb #hb4ff #hh4hchc4ce #hd4gg #gf4ee ,soluble silica #g4ca #e4ef #f4jd #d4bc ,potash 7,k,o7 4#bf 4#cg 4#ee 4#bf 4#gc ,soda 7,na,o7 4#bf 4#bb 4#jh 4#ab 4#ag ,lime 7,ca,o7 4#cd 4#bh 4#be 4#cc 4#bi ,magnesia 7,mg,o7 4#cj 4#bc 4#dh 4#dj 4#bf ---------------------------------------- ----------------------- ,bro4 ox4 of ,manganese 7,mn,o7 4#jd 4#bh 4#gf 4#bb 4#ah ---------------------------------------- ----------------------- ,peroxid of ,iron 7,fe,o7 #e4ah #b4ci #d4hj #c4ga #f4bi ,alumina 7,al,o7 #e4eg #d4ea #f4bh #e4jh #g4aj ,phosphoric acid 7,p,o7 4#jh 4#jh 4#jg 4#ji 4#bf ,sulfuric acid 7,,so7 4#jh 4#jb 4#jf 4#aj 4#aa ,carbonic acid 7,,co7 ---------------------------------------- ----------------------- ,water and organic matter #e4ej #c4aa #d4bj #e4ae #f4fj ---------------------------------------- ----------------------- ,total #ii4gg #ajj4cb #ajj4hhajj4bc #ii4ed ---------------------------------------- ----------------------- ,humus 8 ,ash ,hygroscopic ,moisture #g4bi #d4jh #f4hd #d4ej #h4ga absorbed at ,c #bb;,c #ah;,c ---------------------------------------- ----------------------- ,,short-,,leaved ,,pine4 ---------------------------------------- -------------------------- ,state4 ,north ,south ,mississippi ,louisiana ,carolina,carolina ---------------------------------------- ------------------------- ,county4 ,cabarrus,spartan- ,sumner ,franklin,morehouse burgh ---------------------------------------- ------------------------- ,number of ,sample4 #i #e #adb #ga #bcb ---------------------------------------- ------------------------- ,,analysis ,,of ,,fine ,,earth4 ,insoluble matter #gh4gi #dc4gd #ij4bc #hh4ge #ha4gj #hf4ai #di4fa #ib4ee #ij4ef #hg4de ,soluble silica #g4dj #e4hg #b4cb #a4ha #e4ge ,potash 7,k,o7 4#ac 4#ba 4#bd 4#ad 4#dd ,soda 7,na,o7 4#ja 4#ji 4#ji 4#ji 4#bg ,lime 7,ca,o7 4#cd 4#jc 4#ji 4#jg 4#aj ,magnesia 7,mg,o7 4#ca 4#ba 4#bj 4#ai 4#bd ---------------------------------------- ------------------------ ,bro4 ox4 of ,manganese 7,mn,o7 4#je 4#ja 4#jg 4#jh 4#ci ---------------------------------------- ------------------------ ,peroxid of ,iron 7,fe,o7 #d4ii #aa4gj #a4hd #b4da #c4ee ,alumina 7,al,o7 #d4jb #bf4ed #a4hf #b4bj #d4hg ,phosphoric acid 7,p,o7 4#ad 4#ac 4#ji 4#jh 4#aj ,sulfuric acid 7,,so7 4#jh 4#ja 4#ja 4#ja 4#jh ,carbonic acid 7,,co7 ---------------------------------------- ------------------------ ,water and organic matter #c4hh #aa4fj #b4hc #d4ca #b4ed ---------------------------------------- ------------------------ ,total #ajj4ad #ajj4bb #ii4hg #ajj4ad #ajj4jc ---------------------------------------- ------------------------ ,humus 8 ,ash ,hygroscopic ,moisture #c4fe #aa4ba #c4eg #d4d #e4dg absorbed at ,c #ba4h;,c #ba4h;,c #ba4h;,c ---------------------------------------- ------------------------ ,,upland ,,soils ,,of ,,arid ,,region4 ,,california4 ---------------------------------------- - ,placer ,co4,san ,diego ,ventura ,co4,riverside ,auburn4 ,co4 ,co4 ,national ,arlington4 ,city4 ---------------------------------------- ----------------------- ,number of ,sample4 #ea #dg #ahb #adjf ---------------------------------------- ----------------------- ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ----------------------- ,insoluble matter #gd4ia #gf4da #fi4eb #hf4ba #hb4hd #hd4fa ,soluble silica #g4ic #h4bj ---------------------------------------- ----------------------- ,potash 7,k,o7 4#ch 4#dh 4#fb 4#hg ,soda 7,na,o7 4#jg 4#ad 4#af 4#bi ,lime 7,ca,o7 4#if 4#cf 4#ie #a4eg ,magnesia 7,mg,o7 #a4ji 4#ed 4#if #a4cc ---------------------------------------- ----------------------- ,br4 ox4 of ,manganese 7,mn,o7 4#ci 4#aj 4#jd 4#jd ---------------------------------------- ----------------------- ,peroxid of ,iron7,fe,o7 #ab4db #c4fi #e4jg #d4bj ,alumina 7,al,o7 #aj4ig #e4ab #e4id #e4cj ,phosphoric acid 7,p,o7 4#af 4#bc 4#ac 4#ad ,sulfuric acid 7,,so7 4#ja 4#jc 4#jd 4#ja ,carbonic acid 7,,co7 ---------------------------------------- ----------------------- ,water and organic #e4ad #b4fj #b4fg #a4fj matter ---------------------------------------- ----------------------- ,total #aja4aj #ii4ej #ii4da #ajj4je ---------------------------------------- ----------------------- ,humus #a4ad 4#ef #a4jf 4#bj 8 ,ash #a4ab #a4jd #a4jj 4#fd ,hygroscopic ,moisture #b4cj #f4ei #a4gg absorbed at ,c #ae #ae #ae ---------------------------------------- ----------------------- ,,washington4 ,,montana4 --------------------------------------- ,bunch ,bunch grass ,judith ,near grass ,selah ,valley1 ,gap4 ,bozeman ,ritzville ,rolling ,allen's ,ridge4 ,upland4 ,ranch4 ---------------------------------------- --------------------- ,number of ,sample4 #df #cg #cga #chg ---------------------------------------- --------------------- ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- --------------------- ,insoluble matter #gf4ga #gg4ah #gd4ag #fg4bh #hb4jj #ha4fi #gh4hj #gc4hc ,soluble silica #e4bh #d4ei #d4fa #f4ed ---------------------------------------- --------------------- ,potash 7,k,o7 4#gb 4#fb #a4jg #a4bj ,soda 7,na,o7 4#ji 4#bd 4#af 4#ba ,lime 7,ca,o7 #a4jd #a4cb 4#ga #b4ib ,magnesia 7,mg,o7 4#id 4#ib #a4af #a4dd ---------------------------------------- --------------------- ,br4 ox4 of ,manganese 7,mn,o7 4#je 4#je 4#ig 4#fb ---------------------------------------- --------------------- ,peroxid of ,iron7,fe,o7 #e4ad #e4fb #d4bj #d4fc ,alumina 7,al,o7 #e4gd #e4bd #g4jh #h4ji ,phosphoric acid 7,p,o7 4#af 4#ac 4#ab 4#ah ,sulfuric acid 7,,so7 4#ja 4#je 4#jb 4#ja ,carbonic acid 7,,co7 #a4gf ---------------------------------------- --------------------- ,water and organic matter #d4eh #c4eb #f4ed #e4cg ---------------------------------------- --------------------- ,total #ajj4dh #ii4cg #ii4id #ii4fi ---------------------------------------- --------------------- ,humus 4#ij 4#dh 8 ,ash 4#db 4#cb ,hygroscopic ,moisture #e4fj #d4hd #i4gg #aj4cg absorbed at ,c #ae #ae #ae #ae ---------------------------------------- --------------------- ,soils of the ,humid ,region4--,taking a view1 first1 of the table showing the soils of the humid region1 it appears that the change of vegetation from walnut and hickory to the short-leaved pine bears no visible relation to the increase or decrease of potash or phosphoric acid1 but is plainly governed mainly by the amount of lime present4 ,where the short-leaved pine prevails the soil is almost always either neutral or shows the alkaline reaction in the course of half an hour2 but where the long-leaved pine predominates the soil has almost always an acid reaction4 ,the latter is also usually found in bottoms in which the loblolly pine 7,p4 taeda7 prevails1 and where1 although the soil may show a fair proportion of lime in the analysis1 it does not exist in the form of carbonate4 ,the examples here given are from lands not derived from1 or underlaid by1 limestone formations4 ,where the latter exist the percentage of lime is usually materially increased2 as it is also in the lowlands or bottoms when compared with adjacent uplands 7see above1 chapter #aj1 p4 #afb2 chapter #ah1 p4 #cca72 as well as in the delta lands of rivers4 ,soils of the ,arid ,region4--,even a cursory comparison of the soils of the arid regions of the ,pacific slope with those of the humid1 as given in the above tables1 shows some striking points of difference4 ,the most obvious is the uniformly high percentage of lime1 and usually also of magnesia1 in the arid soils1 and that quite independently of underlying formations1 calcareous or otherwise4 ,this occurs despite the fact that while limestone formations are very prevalent east of the ,rocky ,mountains1 they are quite scarce west of the same4 ,the red 7,laramie7 sandstones of ,wyoming1 the slates of the foothills of the ,sierra ,nevada1 the clay shales1 granites and eruptives of the ,coast ,ranges of ,california1 ,oregon and ,washington1 and the varied black rocks of the great lava sheet of the ,pacific ,northwest1 all alike produce soils of high lime content as compared with ,eastern soils not derived from calcareous formations4 ,this fact has already been referred to1 but is more fully illustrated in the table below4 ,aside from the lime-content1 however1 it will be noted in the preceding table that the potash-content of the arid soils is on the average considerably higher than in those of the humid region4 ,in fact it is hard to find west of the ,rocky ,mountains 7except where high elevation causes a humid climate7 any soils as poor in potash as are many of the commonly cultivated lands of the ,eastern ,united ,states4 ,other ingredients do not show such marked differences from the purely chemical standpoint3 yet1 as will be shown below1 the forms in which silica and alumina occur are also not inconsiderably modified4 ,,general ,,comparison ,,of ,,soils ,,from ,,the ,,arid ,,and ,,humid ,,regions ,,of ,,the ,,united ,,states4#abf--;,in order to verify the conclusions just mentioned upon the broadest basis possible1 the following table has been compiled from all available sources2 partly published1 partly in manuscript only1 having remained in the writer's hands since the cessation of the ,northern ,transcontinental ,survey1 prosecuted from #ahhj to #ahhc1 under the auspices of the ,northern ,pacific ,railroad1 in ,washington and ,montana4 ,the published data are derived partly from the records of ,state surveys1 partly from the soil work connected with the ,tenth ,census2 partly also from those of ,experiment ,stations4 ,in most cases it has of course been necessary to restrict the comparison to such analyses as have been made by substantially identical methods1 for reasons already given2 but in the cases of some states from which numerous analyses made by the ,kedzie method1 adopted by the ,association of ,official ,chemists1 were available1 the average has been given but the name of the state starred1 to indicate that the percentages1 excepting phosphoric acid1 are lower than they would be if made by the method adopted by the writer1 particularly as regards potash4 ,the adoption of the one-millimeter mesh for the fine-earth sieve instead of the half-millimeter size also creates an unfortunate and ineliminable discrepancy4 #abf ,abstracted and revised from ,bulletin ,no4 #c1 ,u4 ,s4 ,weather ,bureau1 #ahic4 ,in order to exhibit clearly the influence of climate as distinct from other local conditions1 it was also necessary to eliminate1 in both the arid and humid regions1 the soils directly derived from1 or connected with calcareous formations2 such as the prairies of the ,southwestern ,states1 the ,bluegrass region of ,kentucky1 etc4 ,this rule having been applied impartially to the soils of both climatic regions1 it can hardly be questioned that the conclusions flowing from a discussion of the results of the comparison are entitled to as much weight as are those of any comparison based on large numbers of observations made1 not with reference to the special point under consideration1 but with a practical object of which the governing conditions were more or less uncertain1 and required to be ascertained by a process of elimination4 ,the table gives1 first1 the averages for each ingredient for each of the states represented1 the number of analyses from which the averages are derived being given in each case4 ,these averages are given separately for the states of the humid and the arid regions respectively2 and at the base of each group the grand average is shown in two forms4 ,the first gives the figures as derived from the aggregate number of soil analyses in each great group1 being #fif for the humid1 #agh for the transition region and #egc for the arid1 divided into the totals resulting from the summation of each ingredient for the whole #fif1 #agh and #egc1 respectively4 ,the second form is that in which the soils of each state are considered as representative of the general character of such state1 as the result of intentional selection2 such as actually occurred in the cases of those included in the census work of #ahhj4 ,the figures given here are therefore the result of a summation of the state averages as such1 and of their division by the number of states represented4 ,it will be noted that while these two modes of presentation do change the figures a little1 yet in either form the same general result is outlined with striking accuracy4 ,it is also notable that notwithstanding the less complete extraction of soil-ingredients in the starred 77states1 the general ratios between arid and humid soils remain substantially the same4 ,for ,western ,oregon1 local calcareous formations compel omission of three lime figures from the averages4 ,,average ,,comparison ,,of ,,soils ,,in ,,the ,,humid ,,and ,,arid ,,regions ,,of ,,the ,,united ,,states4 7,a7 ,number analyzed4 7,b7 ,insoluble ,residue4 7,c7 ,soluble ,silica4 7,d7 ,sum of ,insoluble ,residue and ,soluble ,silica4 7,e7 ,potash 7,f7 ,soda4 7,g7 ,lime4 7,h7 ,magnesia4 7,a7 7,b7 7,c7 7,d7 7,e7 7,f7 7,g7 7,h7 ---------------------------------------- -------------------- ,,humid ,,region4 ,rhode ,island #ghb4da #a4fihd4aj4ae 4#ji 4#dc 4#bg ,north ,carolina #bjha4fc #c4ejhe4ac4ae 4#jf 4#ji 4#jh ,south ,carolina #cjhe4ed #c4cihh4ic4ab 4#jg 4#jg 4#ab ,georgia #djhf4jg #b4hihh4if4ae 4#jg 4#jh 4#aj ,florida #ajhe4cc #a4cchf4ff4jg 4#jc 4#ji 4#jc ,alabama #ejha4eh #d4hihf4dg4bc 4#jg 4#ag 4#ba ,mississippi #ighe4hg #d4ciij4bf4bh 4#aa 4#ae 4#ca ,louisiana #ceha4ab #c4edhd4ff4ai 4#ji 4#af 4#bc ,arkansas #ch #hh4ed4ag 4#jf 4#jh 4#dc ,kentucky #ahe #hf4gb4bj 4#aj 4#jh 4#ai ,ohio #adj #hg4jj4bf 4#ce 4#bh 4#dd ,oregon 7,w4 of ,cascades7 #ddfd4hb #e4chgj4bj4bc 4#ai 4#hc 4#gc ,average for ,humid ,region #fifhd4ag #d4jdhh4ba4ba 4#ad 4#ac 4#bi 8 by ,states #ha4ei #c4dehe4jd4ah 4#aa 4#aa 4#bf ,,transition ,,region4 ,minnesota4 --,semi-humid #addgf4fj #h4gdhe4cd4cj 4#bc 4#fe 4#dc ,north ,dakota4 --,semi-arid #cdfh4dd #g4bhge4gb4db 4#gc 4#ia 4#fd ,average for region #aghge4jd #h4dfhc4ej4cc 4#cb 4#gj 4#dg ,,arid ,,region4 ,montana #eigj4ih #d4agge4ae4hg 4#bga4jca4cf ,idaho #agge4cd #e4bbhj4ef4ef 4#bf 4#hea4aa ,wyoming #bcgf4hf #b4begi4aa4fd 4#daa4iaa4ca ,colorado #afgg4gj #g4ajhd4hj4dd 4#dda4dc 4#ha ,utah #ch #ha4jd4ih 4#eca4gg 4#gc ,arizona #bjfd4ehac4ghgh4cf4hb 4#dcb4cga4hi ,nevada #bbga4gg #e4iegg4gb4ed 4#icb4jd 4#if ,california #bfbff4bh #i4gigf4jg4fa 4#bia4bea4ej ---------------------------------------- -------------------- ,oregon ,east of #ggb4aj #i4fhha4gh4ed 4#bfa4bc 4#gc ,washington ,cascades #ajiga4fj #f4jigg4fi4fe 4#cfa4be 4#if ---------------------------------------- -------------------- ,averages for ,arid ,region #egcfi4af #f4gage4hg4fg 4#cea4dca4bg 8 by ,states #ga4ia #g4aagi4jb4fg 4#dba4faa4ad ---------------------------------------- -------------------- 7,i7 ,br4 oxide ,manganese4 7,j7 ,peroxid of ,iron4 7,k7 ,alumina4 7,l7 ,phosphoric ,acid4 7,m7 ,sulfuric ,acid4 7,n7 ,water and ,organic ,matter4 7,o7 ,hygroscopic ,moisture4 7,p7 ,humus4 7,q7 ,nitrogen in ,humus4 7,r7 ,nitrogen in ,soil4 7,i7 7,j7 7,k77,l77,m7 7,n7 7,o77,p 7 7,q7 7,r7 ---------------------------------------- ------------------------- ,,humid ,,region4 ,rhode ,island 4#jdc4eic4ff4ji4aj #g4dce4bcb4ei ,north ,carolina 4#jgd4gbe4ga4ab4jf #c4ihd4ah ,south ,carolina 4#jeb4dgd4ei4aa4jf #c4cid4bb 4#db ,georgia 4#jib4ged4jb4aa4aj #c4fbc4ed ,florida 4#jh 4#fja4ag4jh4je #a4hia4gb ,alabama 4#abc4hab4gj4ac4je #d4jdg4jg ,mississippi 4#adb4fdd4jg4ji4jc #c4cce4da ,louisiana 4#jbc4abd4bd4aj4je #d4bff4ff ,arkansas 4#bac4ajc4ea4ae4je #c4gjb4dg ,kentucky 4#bjf4jac4eb4aa4jd #c4fia4he ,ohio #c4aac4cf4aa4jd #e4jd ,oregon 7,w4 of ,cascades7 4#ji #aa4fd 4#bc4af #c4bj #a4ee ,average for ,humid ,region 4#acc4hhc4ff4ab4je #d4dj #a4bb 8 by ,states 4#ajc4bfc4fh4ab4jf #c4if #a4eb ,,transition ,,region4 ,minnesota4 --,semi-humid #b4hcd4dc4bb4ja #g4cj #b4ia #f4ec4ai ,north ,dakota4 --,semi-arid #c4fbe4ag4ai4jeac4he #d4fg #g4bh4cd ,average for region #b4jhd4eg4ba4jb #h4ee #c4bd #f4fg4bb ,,arid ,,region4 ,montana 4#cgd4bhf4ha4bb4jf #g4ad ,idaho 4#jbc4hef4ch4af #e4jab4jja4fh #e4ie4aj ,wyoming #c4jef4fa4ah4aa #e4dh ,colorado #c4hbd4ih4bc4jc #c4egb4ca 4#jc ,utah 4#jcc4jhe4ej4bb #f4bgb4cg ,arizona 4#jfd4ibf4dc4ac4jf #c4eg #a4fe ,nevada 4#cbe4fge4jj4cb4ad #e4ic 4#ab ,california 4#jff4fah4dd4aj4jf #d4gdf4jij4iaae4bc4ad ,oregon ,east of 4#jh #aj4ge 4#aatr4 #d4dj 4#fg ,washington ,cascades #e4cgf4ca4ba4jc #e4gge4ad ,averages for ,arid ,region 4#aae4dhg4ba4af4jf #e4aee4dfa4acab4ej4ac 8 by ,states 4#acd4gdf4bg4ai4jg #d4gae4cda4jcaj4ei4aj ---------------------------------------- ------------------------- ,new ,mexico4--,few analyses of ,new ,mexico soils have been made1 but the average results of six partial determinations made by ,goss1 and one full analysis made by ,hare according to the method of the writer1 and given below1 show substantial accord with the averages of the above table4 ,the averages of ,goss' determinations are3 ,potash 4#ghj1 ,phosphoric acid 4#bba1 ,nitrogen 4#ajh per cent4 ,,chemical ,,analysis ,,of ,,rio ,,grande ,,silt 7by ,prof4 ,r4 ,f4 ,hare47 ,deposited on land by irrigation4 ,insoluble matter #fc4gj ,potash 7,k,o7 #a4jf ,soda 7,na,o7 4#bb ,lime 7,ca,o7 #d4ig ,magnesia 7,mg,o7 #b4dc ,br4 ox4 of ,manganese 7,mn,o7 4#ad ,peroxid of ,iron 7,fe,o7 #e4hj ,alumina 7,al,o7 #f4hf ,phosphoric acid 7,p,o7 4#af ,sulfuric acid 7,,so7 4#ac ,carbonic acid 7,,co7 #g4de ,water and organic matter #i4ih ,humus #a4ag 8 ,nitrogen #aa4aa 8 8 per cent4 in soil 4#ac ,hygroscopic ,moisture absorbed at ,c #b4fc ,,discussion ,,of ,,the ,,table4 ,lime4--,considering in this table1 first1 lime1 a glance at the columns for the two regions shows a surprising and evidently intrinsic and material difference1 approximating in the average by totals to the proportion of #a to #aa2 in the average by states1 #a to #ad4 ,this difference is so great that no accidental errors in the selection or analysis of the soils can to any material degree weaken the overwhelming proof of the correctness of the inference drawn upon theoretical grounds1 viz41 that the soils of the arid regions must be richer in lime than those of the humid countries4 ,for the differences in derivation would1 in view of the wide prevalence of limestone formations in the humid regions concerned1 produce exactly the reverse condition of things from that which is actually found to exist2 and if further proof were needed it can readily be found in the detailed discussion of the analyses of the soils of the arid areas forming the contrast4 ,this shows that for instance1 in ,washington highly calcareous soils are directly derived from the black basaltic rocks2 while similarly1 calcareous lands are found in ,california to be the outcome of the decomposition of granites1 diorites1 lavas1 clay-shales and sandstones4 ,it is not easy to overrate the importance of this feature of the soils of the arid region1 as it is intimately connected with other theoretically and practically important facts1 in part already mentioned4 ,summary of ,effects of ,lime ,carbonate in ,soils4--,it is best to summarize1 briefly1 at this point1 the advantages 7and possible disadvantages71 resulting from the presence of a proper amount of lime carbonate in soils1 so far as these are at present understood4 ,physically1 even a small amount of lime carbonate1 by its solubility in the carbonated soil-water1 will act most beneficially in causing the flocculation of clay and in the subsequent conservation of the flocculent or tilth condition1 by acting as a light cement holding the soil-crumbs together when the capillary water has evaporated2 thus favoring the penetration of both water and air1 and of the roots themselves4 ,it should be added that according to the experience of the writer1 amounts of lime carbonate in excess of #b do not add to the favorable effects1 except as would so much sand4 ,as to chemical effects1 among the most important are3-- #a4 ,the maintenance of the neutrality of the soil1 by the neutralization of acids formed by the decay of organic matter1 or otherwise4 #b4 ,the maintenance1 in connection with the proper degrees of moisture and warmth1 of the conditions of abundant bacterial life 7see above1 chapter #i1 p4 #adf72 more especially those of nitrification1 thus supplying the readily assimilable form of nitrogen4 ,also in favoring the development and activity of the root bacteria of legumes1 and of the other nitrogen-gathering bacteria1 such as ,azotobacter 7ibid4 p4 #aef74 #c4 ,the rendering available1 directly or indirectly1 of relatively small percentages of plant-food1 notably phosphoric acid and potash2 as shown in the preceding pages4 #d4 ,the prompt conversion of vegetable matter into black1 neutral humus1 and 7as shown in the case of the soils of the arid region7 the concentration of the nitrogen in the same2 while accelerating the oxidation of the carbon and hydrogen1 as shown by ,s4 ,w4 ,johnson and others4 #f4 ,it counteracts the deleterious influence of an excess of magnesia in the soil1 as first shown by ,loew1#abg and verified by his pupils in ,japan4 #g4 ,in alkali soils1 according to ,cameron and ,may1 it counteracts the injurious action of the soluble salts upon the growth of plants1 not only in the form of carbonate1 but also in those of sulfate and chlorid4#abh #abg ,bull4 ,no4 #a1 ,div4 ,veget4 ,physiol1 and ,plant ,pathol4 ,u4 ,s4 ,dept4 ,agr42 et al4 #abh ,loeb1 ,publications of the ,spreckel's ,physiological ,laboratory of the ,university of ,california1 has shown a similar protective influence of the lime salts in sea-water1 against the other salts1 in the case of the lower marine organisms4 #h4 ,as a matter of experience1 both in the case of grapes and orchard as well as wild fruits1 an adequate but not excessive supply of lime in the soil will produce sweeter fruit than when lime is in small supply4 #i4 ,an excess of carbonate of lime in soils 7from eight to twenty per cent and more71 constituting 8marliness10 tends to seriously disturb the nutrition and general functions of many plants 7calcifuge71 and to produce a suppression or diminution of the formation of chlorophyll and starch2 as in the case of grape vines1 citrus fruits and others1 which nevertheless flourish best in lands moderately calcareous4 ,among the points thus enumerated the third and fourth require some comment4 ,without pretending to define exactly how lime acts in rendering other ingredients more available to plant assimilation1 attention may be called to the fact that lime carbonate may be considered as acting similarly to1 albeit more mildly than1 caustic lime1 in the displacement of other bases from their compounds4 ,it doubtless acts thus in liberating potash from its zeolitic compounds4 ,as to phosphoric acid1 the connection of the effect of lime carbonate with the remarkable availability of that substance when present in the form of tetra-basic salt1 in the case of phosphate slag1 is at least possible4 ,as to the action of lime carbonate in forming humus1#abi no one who has observed the characteristic dark black tint of our calcareous 8prairie soils0 can question the fact2 which moreover is perfectly explicable upon the analogy already alluded to1 with caustic lime1 which1 together with caustic alkalies 7potash and soda71 is known to act powerfully in the conversion of vegetable matter into humus4 ,that instead of liberating the nitrogen in the form of ammonia1 as do the caustic hydrates1 the milder carbonate should only cause the formation of humic amides1 is quite intelligible4 ,that such is really the case1 has been conclusively proved by the investigations of the writer made conjointly with ,m4 ,e4 ,jaffa 7,rep4 ,sta4 ,cal4 ,agr4 ,expt4 #ahib-d72 the general result being that while in the humid region the average nitrogen-content of soil-humus is less than #e1 in the upland soils of the arid region 7where all soils are calcareous7 that percentage rises as high as #bb4j1 with a general average of between #ae and #af4 ,that such highly nitrogenous material can be more readily attacked by the nitrifying bacteria than when a large excess of other oxidable matter is present1 is at least a legitimate presumption1 especially in view of the very active nitrification known to take place in the arid regions everywhere4 ,so long as a large excess of carbohydrates is present1 the oxidation of these will naturally take precedence over that of the relatively inert nitrogen4 ,the accumulation of the latter in the humus-substance of the arid region1 where oxidation of the organic matter of the soil is very active1 points strongly to this view of the case4 #abi 8,black ,soils20 ,agric4 ,science1 ,january1 #ahib4 ,magnesia4--,while the differences in respect to the proportions of lime are the most prominent and decided1 yet the related substance1 magnesia1 shows also a very marked and constant difference as between the soils of the humid and arid regions4 ,it will be observed that the general average for magnesia in the soils of the ,atlantic ,slope is about double that of lime2 ,florida and ,rhode ,island being the only states in which the average is lower for magnesia than for lime4 ,in the arid region1 on the contrary1 magnesia on the general average is nearly the same as lime2 in the average by states1 somewhat less2 thus bringing the ratio for the two regions for magnesia up to one to six or seven4 ,this also is so decisive a showing that no accident could bring it about4 ,we must conclude that climatic influences have dealt with magnesia similarly as with lime2 which from the standpoint of the chemist is just what might be expected1 since magnesia carbonate behaves very much like that of lime toward carbonated waters4 ,that magnesia is a very important plant-food ingredient is apparent from its invariable and rather abundant presence in the seeds of plants1 where it takes precedence of lime4 ,its functions in plant nutrition have been specially investigated by ,o4 ,loew1#acj particularly with respect to its relations to lime4 ,as already stated in connection with the soil-forming properties of magnesian minerals 7see chapter #b71 soils containing large proportions of magnesia generally are found to be unthrifty1 the lands so constituted being frequently designated as 8barrens40 ,loew finds that certain proportions of lime to magnesia must be preserved if production is to be satisfactory1 the proportion varying with different plants1 some of which 7e4 g4 oats7 will do well when the proportion of lime to magnesia is as #a3a1 while others require1 that that ratio should be as #b or #c is to #a1 to secure the best results4 ,in general it is best that lime should exceed magnesia in amount4 #acj ,bull4 ,no4 #ah1 ,div4 ,vegetable ,physiology and ,plant ,pathology2 ,bull4 ,no4 #a1 ,bureau of ,plant ,industry1 ,u4 ,s4 ,dept4 of ,agr42 ,bull4 ,college of ,agriculture1 ,tokyo1 ,vol4 #d1 ,no4 #e4 ,loew explains the injurious action of magnesium salts thus3 ,the calcium nucleo-proteids of the organic structures are transformed in presence of soluble salts of magnesium into magnesium compounds1 while the calcium of the former enters into combination with the acid of the magnesium salt4 ,by this transformation the capacity for imbibition will change1 which must result in a fatal disturbance of functions4 ,the presence of soluble lime salts will prevent that interchange4 ,thus certain alg perished in a solution containing #a per #ajjj of magnesium nitrate1 but remained alive when 4#c per #ajjj of calcium nitrate was added4 ,magnesia seems to be specially concerned in the transfer of phosphoric acid through the plant tissues1 in the form of dimagnesic-hydric phosphate1 which is rather soluble in the acid juices of plants4 ,it is probable that1 apart from the relations just referred to1 such excess of lime as is known to produce chlorosis in plants interferes with the transfer of the magnesic phosphate4 ,some plants1 as already stated1 dispose of an excess of lime by depositing it in the form of oxalate1 while others 7such as the stone crops7 excrete it on the surface of leaves and stems in the form of carbonate4 ,but others seem to possess this power to a limited extent only4 ,in the case of soils containing much magnesia the proper proportion between it and lime may easily be disturbed by the greater ease with which lime carbonate is carried away by carbonated water into the subsoil1 thus leaving the magnesia in undesirable excess in the surface soil4 ,hence the great advantage of having in a soil1 from the outset1 an ample proportion of lime4 ,from this point of view alone1 then1 the analytical determination of lime and magnesia in soils is of high practical value4 ,aso1 ,furuta and ,katayama 7,bull4 ,coll4 ,agr4 ,tokyo1 ,vol4 #d ,no4 #e2 ,ibid4 ,vol4 #f71 have by direct experiment determined the most advantageous ratio of lime to magnesia in several crop plants4 ,they find for rice and oats #a3a1 for cabbage #b3a1 for buckwheat #c3a2 there being apparently a connection between the extent of leaf-surface and lime requirement1 since leaves contain predominantly lime1 while in the fruit1 magnesia predominates4 ,manganese4--,a decided difference in the manganese content of the arid as against the humid soils appears in the table1 the ratio being about #aa3ac in favor of the humid soils4 ,manganese has not been regarded as being of special importance to plant growth in general1 although1 as already stated1 some plants contain a relatively large proportion of manganese in their ashes2 thus1 e4 g41 the leaves of the long-leaved pine of the cotton states4#aca ,but no definite data showing the importance of this element to crops were available until ,loew and his co-workers at ,tokyo#acb established its stimulating action in a number of cases1 in which crop production was materially increased by the use of protoxid salts of manganese4 ,aso#acc applied manganous chlorid to an experimental plot of thirty square meters1 at the rate of twenty-five kilos of ,mn,o per acre1 and thus obtained a yield of rice one-third greater than on the control plot1 at a cost of about #b4jj1 while the value of the increase of the product was nearly #fh4jj4 ,more experimental evidence on this subject is required to establish the general value of the large-scale use of the salts of manganese2 which are obtained in large quantities as a comparatively valueless by-product of the bleaching industries4 #aca ,rep4 ,agr4 and ,geology of ,mississippi1 #ahfj1 p4 #cfj4 #acb ,bull4 ,agr4 ,coll4 ,tokyo1 ,vol4 ,v41 ,nos4 #b and #d4 #acc ,ibid4 ,vol4 #f4 ,the 8,insoluble ,residue40 ,remembering1 in discussing the facts shown by the table1 that the fundamental difference between the regime of the humid and arid regions is the presence in the latter of an almost continuous leaching process1 in which the carbonated water of the soil is the solvent2 remembering1 also1 that the least soluble portion of rocks and soils is quartz or silica 7sand1 as usually understood71 it would be predicable that this ingredient should in the humid region be found to be more abundant in soils than in the arid4 ,this portion is represented by the 8insoluble residue0 of the table4 ,inspection shows that both in the averages of the single states1 and in both of the general averages1 this difference between the soils of the humid and the arid regions of the ,united ,states is strongly pronounced2 the ratio being substantially as #fi in the arid region to #hd in the humid4 ,we must then conclude that the leaching process must have influenced materially other soil ingredients than lime1 which have remained behind in such amounts as to depress the percentage of insoluble residue in the soils4 ,it remains to be shown what are the substances so retained4 ,insoluble and ,soluble ,silica and ,alumina4 ,the ingredient most nearly correlated with the insoluble residue is the free silica which remains behind with it when the acid with which the soil has been treated is evaporated to dryness4 ,the silica is separated from the practically insoluble1 undecomposed minerals by boiling with a strong solution of sodic carbonate4 ,the amount of this 8soluble silica0 is obviously the measure of the extent to which the soil-silicates have been decomposed in the treatment with acid4 ,the most prominent of these is usually supposed to be clay--the hydrous silicate of alumina that in its purest condition forms kaolinite or porcelain earth4 ,any alumina found in the usual course of soil analysis is generally referred to this mineral1 which contains silica and alumina nearly in the proportion of #df to #dj4 ,in very many cases1 however1 the reference of these two ingredients to clay is manifestly unjustified4 ,this is clearly so when 7as not unfrequently happens7 the amount of alumina found exceeds that which would form clay with the ascertained percentage of soluble silica2 it is almost as certainly so when1 in addition to the alumina1 other bases 7notably potash1 lime and magnesia71 are found in proportions which preclude their being in combination with any other acidic compounds present4 ,the only possible inference in such cases is that these bases1 together with at least a portion of the alumina1 are present in the form of hydrated1 and therefore easily decomposable silicates or zeolites4 ,the subjoined analysis by ,r4 ,h4 ,loughridge1 of a clay obtained in the usual process of mechanical soil analysis 7by precipitating with common salt the turbid water remaining after #bd hours subsidence in a column of #bjj millimeters7 from a very generalized soil of northern ,mississippi1 shows one of the many cases in which the numerical ratios of the several ingredients are incompatible with the assumption that silica and alumina are present in combination as clay 7kaolinite7 only3 ,,analysis ,,of ,,colloidal ,,clay4 ,insoluble matter #ae4if ,soluble silica #cc4aj ,potash 7,k,o7 #a4dg ,soda 7,na,o7 #a4gj ,lime 7,ca,o7 4#ji ,magnesia 7,mg,o7 #a4cc ,br4 ox4 of ,manganese 7,mn,o7 4#cj ,peroxid of iron 7,fe,o7 #ah4gf ,alumina 7,al,o7 #ah4ai ,phosphoric acid 7,p,o7 4#ah ,sulfuric acid 7,,so7 4#jf ,carbonic acid 7,,co7 4#jj ,water and organic matter #i4jj ------ ,total #ajj4ad ,if in this case we assign all alumina to silica1 as required for the composition of kaolinite or pure clay1 there yet remains a trifle over twelve 7#ab4ag7 per cent of silica to be allotted to the other bases present4 ,deducting from this the ascertained amount of silica soluble in sodic carbonate1 pre-existing in the raw material 74#ch per cent71 we come to #aa4gi per cent as the amount of silica which must have been in combinations other than kaolinite1 viz41 hydrous silicates1 or soil zeolites1 formed either with the bases other than alumina shown in the analysis or1 more probably1 containing some of the alumina itself in essential combination4 ,we are thus enabled to obtain from the determination of the soluble silica an estimate of the extent to which these soil zeolites1 that form so important a portion of the soil in being the repositories of the reserve of more or less available mineral plant-food1 are present in the soils of the several regions4 ,a glance at the table shows that the general average of soluble silica is very much greater in the soils of the arid regions than in those of the humid1 approximating one to two in favor of the arid division4#acd #acd ,looking at the details of the several states1 we find that on the arid side ,washington has a relatively low figure for soluble silica1 which in the average1 however1 is overborne by the high figures for ,california and ,montana4 ,the explanation of this fact probably lies in the derivation of the majority of the ,washington soils examined1 from lake deposits brought down gradually from the humid region at the heads of the ,columbia drainage1 where sandy beds are very prevalent2 while the country rock--the basaltic eruptives--are very basic1 and moreover slow to disintegrate4 ,in ,california and ,montana the rocks are infinitely varied1 and the general outcome of their weathering is plainly a predominance of complex hydrous silicates in the soils1 as compared with humid regions4 ,differences in the ,sands of the ,arid and ,humid ,regions4--,in chapter #e mention has been made of the fact that while in the humid regions1 8sand0 as a rule means quartz grains1 mostly with a clean surface and very frequently rounded and polished1 in the arid regions even the coarse sand grains consist of1 or are covered with1 a great variety of minerals in a partially decomposed condition4 ,this is owing to the absence of the abundant rainfall which in humid climates continually washes down the finely divided1 half-decomposed mineral matter into the subsoil2 while in arid climates the light rains cannot produce any such washing effect and hence the sand grains remain incrusted with the products of either their own decomposition1 or of that of neighboring particles2 it being therefore not concentrated in the finer portion only1 viz41 the clay and finest silts4 ,this fundamental difference1 which is illustrated in the analytical table below1 at once explains why in the arid regions generally1 sandy soils are found so highly productive that1 owing to their easy cultivation they are preferred to the clayey lands1 in which tillage and irrigation are more difficult4 ,it is a well-known fact that on the 8sands of the desert0 when either irrigated1 or wetted by rain1 vegetation at once springs up with remarkable luxuriance1 even on sand drifts2 and this productiveness appears to be quite as lasting as that of 8strong0 clay soils of the humid regions4 ,this difference is curiously illustrated on the southern edge of the 8black adobe0 or prairie soil area which surrounds ,stockton1 ,cal4 ,here we find on the opposite sides of a small stream 7,french ,camp slough7 the two extremes1 of heavy clay and the sandy soils which for many years made ,stanislaus county the 8banner0 county for wheat4 ,the grain product of both banks ranked alike in quantity and quality in average years2 but in extreme seasons sometimes one1 sometimes the other failed1 according to the weather conditions which favored one or the other soil4 ,no one would think of sowing wheat on so sandy a soil in the humid ,states4 ,table ,illustrating ,difference in ,sands of the ,humid and ,arid ,regions4 ,per cent,potash4,lime4,magnesia4 ,clay4 in ,soil4 ---------------------------------------- -------------------- ,mississippi#ace #ba4fd 4#cb 4#jc 4#bi ,california #abha ,chino#acf #g4fj 4#af 4#ad 4#ag 8 ,jackson#acg #af4dc 4#ac 4#ab 4#jh ,silt 4#jf-4jaf mm4 diam4 ,mississippi #ce4aj 4#da 4#ae 4#cf ,california 7,chino7 #ah4ec 4#bd 4#ec 4#bi 8 ,jackson #cd4ij 4#aj 4#jd 4#jh ,silt 4#jaf-4jbe mm4 diam4 ,mississippi #ac4fg 4#ab 4#ji 4#aj ,california1 ,chino #e4di 4#je 4#aa 4#jb 8 ,jackson #i4if 4#jh 4#jd 4#aj ,silt 4#jbe-4jcf mm4 diam4 ,mississippi ,california1 ,chino #c4ib 8 ,jackson #g4fh 4#jf 4#jb ,silt 4#jcf-4jdg mm4 diam4 ,mississippi ,california1 ,chino #f4dj 4#je 4#ah 8 ,jackson #h4ba 4#jd 4#ja ,coarse ,silt 4#jdg-4jgb mm4 diam4 ,california1 ,chino #g4ib 4#jf 4#bc 8 ,jackson #e4ia 4#ja 4#ja ,fine sand 4#jgb-4ab mm4 diam4 ,california1 ,chino #aa4hg 4#jf 4#bf 8 ,jackson #d4jc 4#ja 4#ja ,sand 4#ab-4ej mm diam4 ,california1 ,chino #cf4aa 4#aa 4#fi 8 ,jackson #aj4aj ---------------------------------------- -------------------- ,phosphoric,soluble,alumina4 ,summ- ,clay4 ,acid4 ,silica4 ation4 ---------------------------------------- ------------------------ ,mississippi#ach 4#jd #g4ag #c4ig #aa4hb ,california #abha ,chino#aci 4#jd #a4gj #a4ce #c4ef 8 ,jackson#adj 4#je #b4hc #b4ac #e4cd ---------------------------------------- ------------------------ ,silt 4#jf-4jaf mm4 diam4 ,mississippi 4#jg #b4hg #a4cf #e4bb ,california 7,chino7 4#jf #d4if #a4gf #g4hd 8 ,jackson 4#jb #b4ej #b4dd #e4ah ---------------------------------------- ------------------------ ,silt 4#jaf-4jbe mm4 diam4 ,mississippi 4#jb 4#cb 4#ag 4#hb ,california1 ,chino 4#ja 4#hj 4#ea #a4ej 8 ,jackson 4#jjg #a4ja #a4ja #b4be ---------------------------------------- ------------------------ ,silt 4#jbe-4jcf mm4 diam4 ,mississippi 4#cf ,california1 ,chino lost 8 ,jackson 4#jjf #j4hb 4#gd #a4gj ---------------------------------------- ------------------------ ,silt 4#jcf-4jdg mm4 diam4 ,mississippi 4#ee trace ,california1 ,chino 4#ja 4#hj 4#fd #a4ff 8 ,jackson 4#jja 4#dc #a4ab ---------------------------------------- ------------------------ ,coarse ,silt 4#jdg-4jgb mm4 diam4 ,california1 ,chino 4#jb 4#hi 4#ei #a4gi 8 ,jackson 4#jjc 4#db 4#cj 4#gg ---------------------------------------- ------------------------ ,fine sand 4#jgb-4ab mm4 diam4 ,california1 ,chino 4#jc 4#ih #a4dc 8 ,jackson 4#jjc 4#bh 4#ji 4#dj ---------------------------------------- ------------------------ ,sand 4#ab-4ej mm diam4 ,california1 ,chino 4#jd #b4dc #a4ei #d4ih 8 ,jackson ,not detd ---------------------------------------- ------------------------ #ace ,analyses by ,r4 ,h4 ,loughridge4 #acf ,analyses by ,l4 ,m4 ,tolman4 #acg ,analyses by ,e4 ,h4 ,lea4 #ach ,analyses by ,r4 ,h4 ,loughridge4 #aci ,analyses by ,l4 ,m4 ,tolman4 #adj ,analyses by ,e4 ,h4 ,lea4 ,it thus appears that while in the ,mississippi soil1 solubility of plant-food practically ceased at grain-diameter of 4#jcf mm1 in the arid ,california soils1 as large an amount was found in the sand-grain sizes between 4#ab and 4#ej millimeters as in the fine silt 4#jaf to 4#jbe mm4 in ,mississippi4 ,hydrous ,silicates are ,more ,abundant in ,arid than ,humid ,soils4--,this predominance of hydrous silicates in the soils of the arid regions should not be a matter of surprise when we consider the agencies which are brought to bear upon these soils with so much greater intensity than can be the case where the solutions resulting from the weathering process are continually removed as fast as formed1 by the continuous leaching effect of atmospheric waters4 ,in the soils of regions where summer rains are insignificant or wanting1 these solutions not only remain1 but are concentrated by evaporation to a point that1 in the nature of the case1 can never be reached in humid climates4 ,prominent among these soluble ingredients are the silicates and carbonates of the two alkalies1 potash and soda4 ,the former1 when filtered through a soil containing the carbonates of lime and magnesia1 will soon be transformed into complex silicates1 in which potash takes precedence of soda1 and which1 existing in a very finely divided 7at the outset in a gelatinous7 condition1 serve as an ever-ready reservoir to catch and store the lingering alkalies as they are set free from the rocks1 whether in the form of soluble silicates or carbonates4 ,the latter have another important effect3 in the concentrated form at least1 they1 themselves1 are effective in decomposing silicate minerals refractory to milder agencies1 such as calcic carbonate solution2 and thus the more decomposed state in which we find the soil minerals of the arid regions is intelligible on that ground alone4 ,it must not be forgotten that lime carbonate1 though less effective than the corresponding alkali solutions1 nevertheless is also known to produce1 by long-continued action1 chemical effects similar to those that are more quickly and energetically brought about by the action of caustic lime4 ,in fact1 the agricultural effects of 8liming0 are only in degree different from those produced by marling with finely pulverized carbonate2 and in nature the same relation is strikingly exemplified in the peculiarly black humus that is characteristic of calcareous lands1 but which can be much more quickly formed under the influence of caustic lime on peaty soils4 ,in the analysis of silicates we employ caustic lime for the setting-free of the alkalies and the formation of easily decomposable silicates1 by igniting the mixture2 but the carbonate will slowly produce a similar change1 both in the laboratory and in the soils in which it is constantly present4 ,this is strikingly seen when we contrast the analyses of calcareous clay soils of the humid region with the corresponding non-calcareous ones of the same4 ,in the former the proportions of dissolved silica and alumina are almost invariably much greater than in the latter1 so far as such comparisons are practicable without assured absolute identity of materials4 ,that is1 calcareous clays or clay soils are so sure to yield to the analyst large precipitates of alumina1 that experience teaches him to employ smaller amounts for analysis than he would of non-calcareous materials1 in order to avoid unmanageably large bulks of aluminic hydrate4 ,it is but rarely that even the heaviest non-calcareous soils yield to the acid usually used in soil analysis more than #aj per cent of alumina2 while heavy calcareous clay 7prairie7 soils commonly yield between #ac and #bj per cent4#ada ,it would be interesting to verify this relation by artificial digestions of one and the same clays with calcic carbonate at high temperatures1 as it must always be extremely difficult to insure absolute identity of all other conditions in natural materials4 ,in most of these cases1 what is true of alumina is also true of the soluble silica4 ,but since the latter is constantly liable to be dissolved out by solutions of carbonated alkalies1 it is not surprising that this relation is not always shown4 #ada ,report of the ,tenth ,census1 ,vols4 #e #f2 see especially the analyses of soils from ,mississippi and ,alabama4 ,also the ,reports of the ,california ,experiment ,station4 ,aluminic ,hydrate4--,in numerous cases1 the amount of alumina dissolved in analysis is greatly in excess of the soluble silica1 so as to force the conclusion that a portion of the latter must be present in a different form from that of clay 7kaolinite72 the only choice being between that of complex hydrous silicates 7none of which1 however1 could contain as large a percentage of alumina as clay itself7 and aluminic hydrate4 ,the latter is alone capable of explaining the presence of more alumina than silica in easily soluble form2#adb and the visible occurrence of 8gibbsite0 and 8bauxite0 in modern formaations renders this a perfectly simple and acceptable explanation4 ,since these minerals are known to be incapable of crystallization1 we are moreover led to the presumption that it will as a rule be found in the finest portions of the soil1 viz41 in the 8clay0 of mechanical analysis4 #adb ,excepting the relatively rare minerals of the ,allophane1 ,kollyrite1 and ,miloshite group4 ,some illustrations of these conditions are given below1 for soils from ,mississippi and ,california4 ,the soluble silica being all assigned to kaolinite1 the rest of the alumina must be assumed to be present as hydrate1 since no other compound could fulfil the stoichiometrical requirements4#adc ,the table therefore shows the differences between the amounts of alumina found by analysis1 and those assignable to kaolinite1 calculated to the mineral bauxite--the most abundant1 as well as the one containing the medium proportion of water1 among the three naturally occurring aluminic hydrates4 ,,table ,,showing ,,excess ,,of ,,alumina ,,over ,,silica ,,in ,,soils2 ,,calculated ,,as ,,bauxite4 7,a7 ,total soluble in ,h,cl4 7,b7 ,corresponding to ,bauxite4 7,c7 ,other ,soluble ,matters4 ,miss4 ,mississippi4 ,cal4 ,california4 ---------------------------------------- -------------------- ,number4 ,name of ,soil4 ,county4 ,state4 7,a7 ,si,o,al,o 7,b7 7,c7 ---------------------------------------- -------------------- #aie ,prairie ,alcorn ,miss4#bh4eg #c4f #ad4dad4ab #b4ib #cdf ,dark ,loam ,chicasaw 8 #aj4cb #f4f #aa4b #f4ia 4#hf #bhh ,flatwoods ,clay ,pontotoc 8 #bf4id #e4j #aa4c #h4ge #c4dh #fgf ,red ,volcanic ,lake ,cal4#da4jj #e4i #bb4fba4ij #b4jj #ccb ,mojave ,desert ,kern 8 #bd4hb #e4j #i4b #f4aj #e4ac #aia ,red ,foothill ,merced 8 #bc4cb #d4e #h4h #f4bj #c4je ---------------------------------------- -------------------- #gje ,red ,chaparral ,shasta 8 #bh4ge #e4e #ad4dab4aj #a4ab #gjf 8 8 ,subsoil 8 8 #bh4dj #d4g #ag4daf4gj #a4cb ---------------------------------------- -------------------- #egc ,tulare ,plains ,tulare 8 #bi4bg #c4d #h4g #g4bjaa4af #gja ,dry ,bog 8 8 #bg4bi #d4c #ab4daj4ij #e4jd #ajjd 8,slickens8 ,sed4,butte 8 #cj4hj #h4j #ad4b #i4bj #a4ie #fef 8 8 ,yuba 8 #bb4bc #c4j #aj4d #i4hj #b4ai #eag ,brownish ,loam ,butte 8 #bi4hj #d4h #ab4j #i4hj #d4db #efa ,black ,loam 8 8 #cj4ba #c4b #ac4jab4hj #d4fg ---------------------------------------- -------------------- #efc ,sacramento ,alluvium 8 8 #bc4df #b4g #aj4daj4ij #d4eh ---------------------------------------- -------------------- #hfc ,red ,foothill ,nevada 8 #ef4hjaa4j #cf4dcc4fj #a4bb #hfa 8 8 8 8 #de4dfaa4e #bb4jad4aj #c4ig ---------------------------------------- -------------------- ,it is apparent from this table that if1 as is probable1 the aluminic hydrate accumulates in the 8clay0 of the analysis1 it will in some cases form a very considerable percentage of the same1 and detract to that extent from its plastic1 adhesive and other properties4 ,but it must be remembered that the assumption upon which this table is calculated1 leaves out of consideration the zeolitic portion1 which as the #fth column shows1 is frequently quite large as measured by the bases found1 to which no other form of combination can be assigned4 ,since some of the alumina undoubtedly takes part in the formation of such zeolites1 the silica must to that extent be withdrawn from the estimate made for kaolinite4 ,while it is impossible to make any definite numerical allowance for this fact1 it clearly will tend in many cases to increase materially the amount of alumina that must be assigned to the hydrate condition4 ,it will be noted that in most cases given1 the alumina per cent is rather large4 #adc ,since any complex zeolite would contain less alumina than kaolinite1 this assumption more than covers the possible zeolitic alumina4 ,the relatively large number of such cases shown in the table for ,california soils is not a matter of accident2 for even a cursory glance at the columns of analyses of ,california 7and ,washington and ,montana7 soils1 shows that the cases in which the alumina exceeds the silica in amount are rather predominant1 while the reverse is the case in the humid region4#add ,but it must not be inferred that the reverse relation is not also frequently observed even in the arid region2 it occurs in fact in close proximity to the localities where some of the most striking instances of excess of alumina over soluble silica have been found4 #add ,see for comparison the data given in vols4 #e and #f of the report of the ,tenth ,census of the ,united ,states4 ,thus ,nos4 #hfa and #hfc from the neighborhood of ,grass ,valley1 which show this excess most strikingly1 occur within #ae miles of localities which show almost the reversal of the numbers given for the two former1 and at a level of about a thousand feet lower4 ,it would seem1 on the whole1 that the excess of alumina occurs most frequently in connection with soils formed from eruptive rocks2 in the case referred to1 from volcanic ash4 ,it will require more detailed study to detect the causes of these marked differences4 ,retention of ,soluble ,silica in ,alkali ,soils4--,it is somewhat surprising that1 contrary to the expectation one would naturally entertain1 the alkali lands1 so frequently rich in the carbonates of the alkalies that would dissolve free silica1 on the contrary1 show most frequently an excess of soluble silica over alumina4 ,this is probably to be explained from the very liberal opportunities afforded in the alkali soils for the formation of complex zeolitic masses by the retention in soil of the soluble alkali salts1 and the abundance of lime always present in them4 ,as already stated1 we usually find in alkali soils a very large proportion of both alkaline and earthy bases in acid-soluble silicate combinations4 ,but much farther research is needed to explain fully the marked discrepancies observed in this respect between soils not only occurring in closely contiguous localities1 but also showing marked similarities in their general composition4 ,ferric ,hydrate4--,there is no obvious reason1 from the chemical standpoint1 why iron1 that is1 ferric hydrate or iron rust1 should be more abundant in the soils of the arid regions1 as the averages given in the table suggest2 moreover1 the fact does not impress itself upon the eye1 since the orange or reddish tints are by far more common in the humid than in the arid regions of the ,united ,states at least4 ,the ,california average is considerably influenced by the very highly ferruginous soils from the foothills of the ,sierra ,nevada1 and by the black 7magnetite7 sand so commonly present2 that of ,oregon by the black1 highly ferruginous country rock 7basalts71 from which they are partly derived4 ,the average for ,montana is not higher than that of three states of the humid region1 and less than that of ,kentucky4 ,we might imagine a cause for depletion of iron in the soils of the humid areas in the frequency with which humid moisture and high temperature will during the summers concur toward the bringing about of a reducing process in the soil1 which by getting the iron into proto-carbonate solution would make it liable to be leached into the subsoil1 as is frequently the case2 yet the resulting 8black gravel0 or bog ore1 in its various forms1 is of not infrequent occurrence in the arid regions also4 ,a constant quantitative difference due to climatic conditions does not appear to be shown by the data thus far at command1 but the finer distribution of the ferric hydrate in the humid temperate as well tropical regions is obvious to the observer1 from the frequent redness of humid and tropical soils4 ,manganese4--,an unexpected and apparently well-defined contrary relation appears to be shown as regards the related metal manganese2 the average percentage of which is in all cases less in the arid than in the humid region4 ,the cause of this relation is altogether obscure2 it is too frequent to be accidental4 ,phosphoric ,acid4--,as regards that highly important soil ingredient1 phosphoric acid1 the indication in the table that there is no characteristic difference in the average contents in soils of the arid and humid regions1 respectively1 is doubtless correct4 ,this substance is so tenaciously retained by all soils that there is no obvious reason why there should be any material influence exerted upon its quantity by leaching1 or by any of the differences in the process of weathering that are known to exist between the two climatic regions4 ,moreover1 it is apparent that the average for the arid region is made up out of very widely divergent figures2 that of ,california exceptionally low 7lower than any of those for the states of the humid regions71 while those for ,washington and ,montana are exceptionally high4 ,the latter is due to country rocks 78basalts07 showing abundance of microscopic crystals of apatite1 which in some cases raise the contents of the soils in phosphoric acid to nearly twice the average given for the states4 ,the forecast that for most ,california soils1 fertilization with phosphates is of exceptional importance1 has already been abundantly confirmed by cultural experience4 ,few definite data are as yet available from other arid states1 where fertilization is thus far sporadic and unsystematic4 ,but it is predictable that in view of the presence of an excess of lime carbonate in the arid soils1 and the unfavorable effect of this compound on the rapid solubility of tri-calcic phosphate demonstrated by ,schloesing1 ,jr41#ade by ,bttcher and ,kellner#adf and ,nagaoka1#adg fertilization with readily available phosphate fertilizers will be found necessary among the first1 all over the arid region1 especially in view of the scarcity of humus in arid soils4 #ade ,ann4 ,sci4 ,agronomique1 tome #a1 #ahii4 #adf ,landw4 ,presse1 #aijj1 ,no4 #eb2 ibid4 #aija1 ,nos4 #bc and #bd4 #adg ,bull4 ,univ4 ,tokyo1 ,vol4 #f1 ,no4 #c4 ,production was diminished to less than one half when lime was used with bone meal1 and actual assimilation of phosphoric acid to one fifth4 ,a curious instance of the effects of continued warm maceration in rock decomposition is afforded by the highly ferruginous soils derived from the black basaltic lavas of the ,hawaii ,islands4 ,these lavas1 like the basalt sheet of the ,pacific ,northwest1 contain a large amount of crystallized phosphate minerals1 notably apatite and vivianite4 ,a correspondingly large proportion of phosphoric acid is found in the soils derived from these rocks1 up to nearly two per cent4#adh ,but almost the entirety of this substance is present in the form of an insoluble1 basic iron compound1 difficultly soluble even in acids1 and rendering it wholly unavailable to vegetation4 ,so that actually the most pressing need of most of these soils is phosphate fertilization4 ,the same is probably true of some of the highly ferruginous soils of ,california and of the ,cotton ,states4 #adh ,see table1 chapter #ai1 p4 #bef4 ,sulfuric ,acid4--,from the absence of the leaching process in the soils of the arid region1 we should expect that sulfates would be more abundant in them than in the soils of the humid4 ,this is certainly true in the case of the alkali soils1 which are characteristic of the regions of deficient rainfall4 ,see below1 chapter #bb4 ,hence the showing made in the general table1 indicating that sulfates are equally abundant in the soils of the humid than in those of the arid regions1 is surprising in view of the efflorescences of alkali sulfates so frequently observed in the latter4 ,this is obviously due to the fact that the majority of such alkali soils has1 on account of their local nature and usually heavy lime content1 been excluded from the comparison2 which otherwise would have made a very different showing4 ,potash and ,soda4--,the compounds of the alkali metals potassium and sodium1 being on the whole much more soluble in water1 even without the concurrence of carbonic acid1 than those of calcium and magnesium1 the leaching process that creates such pronounced differences in the case of the two earths must affect the alkali compounds very materially4 ,comparison of the soils of the two regions in this respect shows1 indeed1 very great differences in the average contents of potash and soda4 ,for potash the ratio is 4#baf to 4#fgj per cent on the general average1 and 4#ahg to 4#fgj per cent1 in the average by states2 for soda1 4#adj per cent to 4#cej per cent on the general average1 and 4#aaj per cent to 4#dbj per cent in the average by states4 ,for both1 therefore1 the general average ratio is as one to between three and four for the humid as against the arid region4 ,it is curious that an approximation to the ratio of one to two1 or somewhat less1 is maintained in the average proportion of soda to potash in both regions2 but this does not by any means hold good in detail1 very high potash-percentages being often accompanied by figures for soda very much below the above ratio4 ,this is the result of an important difference in the chemical behavior of the two alkalies1 which has already been alluded to in connection with the discussion of the zeolites4 7,see chapter #c1 p4 #ch74 ,the process of 8kaolinization10 being that by which clays are formed out of feldspathic minerals and rocks such as granite1 syenite1 trachyte1 etc41 results in the simultaneous formation of solutions of carbonates and silicates of potash and soda4 ,these coming in contact with the corresponding compounds of lime and magnesia1 also common products of rock decomposition1 are partly taken up by the latter1 forming complex1 insoluble1 hydrous silicates 7zeolites74 ,in these1 however1 potash whenever present takes precedence of soda2 so that when a solution of a potash compound is brought in contact with a zeolite containing much soda1 the latter is partially or wholly displaced and1 being soluble1 tends to be washed away by the rainfall into the country drainage4 ,hence potash1 fortunately for agriculture1 is tenaciously held by soils1 while soda accumulates only where the rainfall or drainage is insufficient to effect proper leaching1 and in that case manifests itself in the formation of what is popularly known as 8alkali soils20 namely those in which a notable amount of soluble salts exists1 and is kept in circulation by the alternation of rainfall and evaporation1 the latter causing the salts to accumulate at the surface and to manifest themselves in the form of saline crusts or efflorescenses4 ,alkali lands are a characteristic feature of all regions of scanty rainfall1 and are found more or less on all the continents4 ,the substances composing the alkali salts are retained not only in their soluble form1 but by their continued presence influence profoundly1 in several ways1 the processes of soil formation4 ,a more detailed discussion of this important subject is given in chapters #bb and #bc4 ,arid ,soils are ,rich in ,potash4--,one of the most important practical conclusions flowing from the comparison of the potash contents of the humid and arid soils respectively is that while in the former1 potash is usually among the first substances to be supplied by fertilization when production languishes1 in the arid regions it will as rule come last in order among the three ingredients commonly so furnished4 ,aside from the water-soluble potash salts always forming part of the salts of the alkali lands proper1 which in many cases will alone hold out for many years under the demands of cultivation1#adi they rarely contain much less than one per cent of acid-soluble potash2 occasionally rising as high as #a4h per cent4 ,that in such lands potash-fertilization is uncalled-for and ineffective1 hardly requires discussion2 while on the other hand1 phosphates are commonly required for full production after ten or fifteen years of cultivation without returns4 ,nitrogen usually comes next in order1 but sometimes is the first need4 #adi ,in the light alkali lands of the southern ,california ,experiment ,substation at ,chino1 the average content of water-soluble potash in ten acres amounts to the equivalent of #a1bjj pounds of potash sulphate per acre4 ,outside of this the acid-soluble potash of the soil is 4#ie41 equal to #ch1jjj pounds per acre-foot4 ,the constant indiscriminate purchase and use of all three ingredients1 so urgently recommended by fertilizer manufacturers because of their success in the humid ,eastern ,states1 is therefore very poor economy for the farmers of the arid region4 ,excepting cases of very intense culture1 e4g4 of vegetables or berries1 the use of potash salts is but rarely remunerative1 and therefore uncalled-for1 in arid soils for a number of years4 ,humus4--,the figures shown in the table for the average humus-percentages in the soils of the two regions do not adequately represent the very important differences actually existing2 partly because of the inadequate number of determinations made by the same method 7,grandeau's71 partly because of the differences in the composition1 and especially in the nitrogen-content of this substance1 which render direct comparison delusive4 ,a detailed discussion of the marked differences existing between the humus of arid and humid soils in this respect has already been given 7chapter #h1 p4 #ace72 showing that the high nitrogen-percentage in the arid humus probably compensates largely the lower humus-percentage1 while rendering nitrification more rapid1 because the oxygen is not consumed by overwhelming amounts of carbon and hydrogen2 which1 as is already known1 take precedence of nitrogen in the oxidation of humus substances4 ,nitrates are almost always more abundant in the soils of the arid region than in those of the humid1 sometimes to the extent of influencing injuriously the quality of certain crops1 such as tobacco and sugar beets4 ,nevertheless1 nitrogen is ordinarily1 in the arid region1 the substance requiring replacement next to phosphoric acid4 ,and when considered in connection with the small humus-content1 so liable to burning-out1 this places green-manuring with leguminous plants among the first and most vital improvements to be employed there4 ,the ,transition 7semi-humid or semi-arid7 ,region4--,the sloping plains country lying between the ,rocky ,mountains and the ,mississippi1 quite arid at the foot of the mountains1 but with rainfall increasing more or less regularly to eastward1 form a transition-belt between the arid and humid region of which but a small portion has been systematically studied in respect to its soil formations4 ,the analyses made of soils of the two adjacent states of ,minnesota and ,north ,dakota1 have been placed in the general table 7p4 #cgg7 to show how far in their general relations their soils correspond to the generalizations deduced from the comparison of the decidedly arid and humid soil areas chiefly represented in the table4 ,although it has not been possible1 for lack of detailed data1 to eliminate the soils originating from calcareous formations1 it will be seen that those of semi-arid ,dakota differ from those of more humid ,minnesota1 almost throughout1 as would be anticipated from the studies of the extremes1 given in this chapter4 ,,chapter ,,xxi4 ,,soils ,,of ,,arid ,,and ,,humid ,,regions 7,continued74 ,,soils ,,of ,,the ,,tropics4 ,within the ordinary limits of atmospheric temperatures1 and in the presence of adequate moisture1 chemical processes active in soil-formation are intensified by high and retarded by low temperatures1 all other conditions being equal4 ,we can usually artificially imitate1 and produce in a short time by the application of relatively high temperatures1 most of the chemical changes that naturally occur in soil-formation4 ,while it is true that the changes of temperature are nearly as great in the tropical as in the temperate climates1 these changes all occur at a higher level and within the limits favoring bacterial and fungous action4 ,this being true we should expect that the soils of tropical regions should1 broadly speaking1 be more highly decomposed than those of the temperate and frigid zones1 and that the intensified processes continue currently4 ,this fact has not been as fully verified as might be desirable1 by the direct comparative chemical examination of corresponding soils from the several regions1 owing to the want of uniformity in methods and the fewness of such investigations in tropical countries4 ,yet the incomparable luxuriance of the natural as well as artificial vegetation in the tropics1 and the long duration of productiveness that favors so greatly the proverbial easy-going ways and slothfulness of the population of tropical countries1 offers at least presumptive evidence of the practical correctness of this induction4 ,in other words1 the fallowing action1 which in temperate regions takes place with comparative slowness1 necessitating the early use of fertilizers on an extensive scale1 is much more rapid and effective in the hot climates of the equatorial rainy belt2 thus rendering currently available so large a proportion of the soil's intrinsic stores of plant-food1 that the need of artificial fertilization is there largely restricted to those soils of which the parent rocks were exceptionally deficient in the mineral ingredients of special importance to plants1 that ordinarily form the essential material of fertilizers4 ,quartzose1 magnesian1 and other soils resulting from the decomposition of 8simple0 rocks will1 of necessity1 be poor in plant-food everywhere4 ,humus in ,tropical soils4--,another inference from the climatic conditions of the tropics is that the properly tropical soils are likely to be rich in humus1 as a result of the luxuriant vegetation which in the decay of its remnants must leave abundant humic residues4 ,this seems to be generally verified wherever the interval between rainy seasons is not too long2 for otherwise1 under the great and constant heat of the tropics a rapid burning-out of the humus1 such as is known to occur in the arid regions1 must also take place4 ,a good example illustrating the inter-tropical regime as regards humus is given in the table in chap4 #h1 p4 #acg1 showing the humus-content of some ,hawaiian soils4 ,both are of the same order as in the soils of the temperate humid region1 though the nitrogen-content evidently can1 consistently with productiveness1 range lower than has thus far been observed in temperate climates4 ,this again forms a striking contrast with the soils of the arid regions4 ,it is greatly to be regretted that not even approximate determinations of the organic matter1 much less of the humus-substance proper1 have been made by any of those who have analyzed tropical soils2 excepting those made of ,hawaiian soils at the ,california ,experiment ,station4 ,the 8loss by ignition0 is of course always very largely water1 mostly referable to ferric hydrate and clay substance1 the latter presumably essentially in the form of kaolinite4 ,when1 therefore1 ferric oxid and alumina have been determined1 we may approximate to the amount of total organic matter by making allowance for ferric hydrate at the rate of about #ad of the ferric oxid1 for kaolinite at that of #cd4ib of the alumina found4 ,deducting these amounts of water from the total 8loss by ignition10 we may obtain at least an approximate idea of the organic matter1 and the probable availability of the nitrogen determined by the analysis4 ,see chapter #ai1 p4 #ceg4 ,while the continuous heat and moisture of the tropics concur toward rapid rock decomposition1 it must be remembered that the copious rainfall is equally conducive to an intense leaching effect4 ,striking examples of this action occur in the ,hawaiian ,islands1 in the highly ferruginous soils resulting from the decomposition of the black 7pyroxenic and hornblendic7 lavas that are so characteristic of the volcanic effusions of that region4 ,the soils formed from these rocks are sometimes so rich in ferric hydrate 7iron rust7 that they might well serve as iron ores elsewhere4 ,but these soils are very unretentive1 and though very productive at first they are soon exhausted1 the abundant rains having sometimes deprived them of almost every vestige of lime1 and of most of the potash contained in the original rock4 ,at the same time the abundant phosphoric acid of the original rock has been reduced to almost total unavailability by combination with ferric oxid1 just as in the case of the bog ore of the temperate climates2 so that phosphate fertilization is urgently needed in these lands1 though showing high percentage of phosphoric acid4 7,chap4 #ai1 p4 #cef47 ,soils highly colored by ferric hydrate occur rather frequently in the tropics1 and have received the general name of 8laterite0 soils4 ,curiously enough1 the intense reddish tint mostly shown in these soils1 and which is emphasized in the 8terra roxa0 of the ,brazilians1 and the general 8red0 aspect of ,madagascar1 and of the ,malabar and ,bengal coasts1 is by no means always accompanied by markedly high percentages of iron oxid2 but the latter is very finely diffused1 so as to be very effective in coloration4 ,the plant-food percentages of tropical soils are generally quite low1 so that in the temperate humid regions such lands would be adjudged to be rather poor4 ,yet they mostly prove quite productive and lasting1 even without fertilization4 ,this is doubtless to be explained by the continuous and rapid rock and soil-decomposition which goes on under tropical climatic conditions1 already alluded to2 so as to supply enough available plant-food for the demands of each season's vegetation1 analogously to the proverbial 8nimble penny40 ,this is supplemented also by the rapid decay and leaching-out of the ash ingredients of the rapidly decaying and dying vegetation4 ,nitrification must likewise1 of course1 be very active under the continual heat and moisture1 and the humus formed under these circumstances is likely to be quite poor in nitrogen4 ,on this latter point1 however1 definite data are almost wholly wanting4 ,investigations of ,tropical ,soils4--,the most extended chemical investigations of properly tropical soils have been made by ,wohltmann in his investigations of the soils of ,india1 ,german ,southwest and ,southeast ,africa1 and ,samoa2#aej and by ,mntz and ,rousseaux of soils collected under ,government auspices in ,madagascar4 ,leather1 ,bamber and ,mann have also analyzed a large number of soils of ,india4 ,but we find in many of these cases a failure to specify distinctly the local climatic conditions1 and even the depth to which the samples have been taken2 so that the investigator is obliged to examine laboriously the local climates1 and especially the amount and distribution of rainfall1 before being enabled to discuss intelligently the data given4 ,even ,wohltmann1 in his discussion of ,north ,african and ,saharan soils1 classes these distinctly arid types among the tropical ones4 #aej ,samoa ,erkundung1 by ,f4 ,wohltmann1 ,kolonial-,wirthsch4 ,komitee1 ,berlin1 #aijd4 ,again1 the dry seasons intervening between the tropical rains1 varying in length and from locality to locality1 obscure somewhat the relations of the soils to the climatic conditions4 ,under the lee of mountains1 even of slight altitude1 we find xerophytic 7arid-land7 vegetation1 as has been noted by many observers in ,brazil1 even near the ,amazon2 in ,hawaii1 in ,jamaica1 and in ,madagascar4 ,unless1 therefore1 a close discrimination is exercised by field observers1 many contradictory results will appear in analyses of soils of inter-tropical countries4 ,this is naturally the case in ,india1 where the topographic surface conformation and seasonal climatic conditions are so complicated and contrasted4 ,on the whole1 the results obtained in ,samoa1 ,kamerun and ,madagascar seem1 of those available1 to be the most characteristic of true tropical conditions4 ,in comparing these with the soils of low plant-food percentages in the temperate humid region 7see chapter #ai1 p4 #ceb71 it must be remembered that those mentioned as being productive are so by virtue of great depth and relatively high proportions of lime2 while in the tropics1 the intense leaching process prevents lime from reaching any high absolute or relative percentages1 save where limestone formations prevail4 ,moreover1 the mode of preparation of the soil extracts for analysis by ,wohltmann1 and by ,mntz and ,rousseaux1 differ so widely from that forming the basis of discussion of soil-composition in this volume1 that it becomes necessary to make separate allowances in each case2 since some of the ingredients1 phosphoric acid1 lime and magnesia1 are fully dissolved by the weaker treatments1 while others1--e4 g41 potash--are not1 and are therefore not directly comparable with the data obtained in the writer's work4 ,the analyses made in ,india by ,leather and others have apparently been made substantially in accordance with the author's methods and may be considered directly comparable4 ,,soils ,,of ,,samoa ,,and ,,kamerun4 ,wohltmann has investigated the soils of ,samoa1 notably those of the main island of ,upolu1 under the auspices of the ,german 8,kolonial-,wirthschaftliche ,komitee0 in #aijc1 and gives the results of his observations and analyses in a report published at ,berlin in #aijd4 ,the analyses are quite numerous1 but unfortunately are made by a special method which renders them only partly comparable with those of any other analyst4 ,wohltmann's method is this3 8#dej grams of fine earth 7below #b millimeters diameter7 is treated for #dh hours with #a liters of cold chlorhydric acid of #a4ae density4 ,another portion1 designed for a fuller determination of potash1 is treated for one hour with the same acid1 boiling hot4 ,potash was determined in both soil extracts2 the hot extract gave from one-third to twice the amount obtained in the cold extraction40#aea ,wohltmann justifies this method by the statement that it has yielded him results more nearly in accord with experience than any other tried1 both with tropical and ,european soils4 ,under these conditions only a few of the determinations in ,wohltmann's analyses are directly comparable with those upon which the discussions in this volume have been based4 ,the figures for nitrogen and phosphoric acid may be assumed to be fully comparable2 that of lime will in general represent fully only that which is present in the forms of carbonate1 sulfate and humate1 and a part of that existing in zeolitic or hydrous silicate form4 ,of the two potash determinations only the one made in hot extraction will be even remotely comparable1 being probably at least #cj lower than would have been obtained by the writer's method4 #aea ,wohltmann states that the hot extraction sometimes yielded as much as five times more than the cold2 but no such case appears in his reports on ,samoa and ,kamerun4 ,even thus1 however1 ,wohltmann's results are highly instructive4 ,he gives the following summary of his mode of interpreting such analyses3 ,very rich4 ,good4 ,inadequate4 ---------------------------------------- ---------- ,potash 4#b 4#a 4#je ,lime and ,magnesia #a4j 4#d 4#jg ,phosphoric acid 4#b 4#a 4#jf ,nitrogen 4#b 4#a 4#je ---------------------------------------- ---------- ,it will be observed that the figures of this table differ materially only in the matter of potash from those given in chapter #ai1 p4 #ced2 for the latter substance they would have to be multiplied by from #b to #d1 according to the lime-content and other conditions4 ,with this understanding a number of ,wohltmann's analyses of soils from ,samoa and ,kamerun are given below1 the potash determinations made with hot acid being placed in parentheses after the other4 ,soils of ,samoan ,islands4--,a discussion of these analyses shows1 from the writer's point of view1 a very low content of potash and lime1 with the peculiarity that both are somewhat higher at the depth of a meter than in the surface ten-inches4 ,this is probably to be accounted for from the very high content of organic matter 7humus71 which is apparent from the high 8loss by ignition10 a very large proportion of which must be credited to the burning of the organic matter4 ,that this humus reaches to the lowest depths examined1 is clear from the nitrogen-content given for these samples4 ,wohltmann1 whose estimate of these soils agrees in most respects with the writer's1 attributed to them a very satisfactory nitrogen-content4 ,this would be true of the total2 but as he has not determined either the true humus or its nitrogen-content1 it remains uncertain whether or not a sufficiency is in an available form1 and whether their case may not be like that of the ,hawaiian soil mentioned above 7chapter #ai1 p4 #cfb71 in which despite #aj of humus and 4#ag of nitrogen1 the land was found to be nitrogen-hungry4 ,again1 as regards the phosphoric acid1 which ,wohltmann considers satisfactory to high1 it is questionable to what extent it is rendered unavailable by the very high content of ferric hydrate4 ,we are thus left in some uncertainty as to the real manurial requirements of the ,samoan soils1 which doubtless represent very closely also those of ,tutuila1 the chief ,american island of the group4 ,,analyses ,,of ,,tropical ,,soils ,,by ,f4 ,,wohltmann4 ,extraction with cold chlorhydric acid1 sp4 g4 #a4ae1 for #dh hours4 7,a7 ,tuanaimato4 ,virgin ,forest ,soil1 not given4 7,b7 ,le ,utu ,sao ,vaa ,cultivated ,soil4 7,c7 #j--be cm4 7#aj ins47 7,d7 #ge--ajj cm4 7#cj--dj ins47 ,,samoan ,,islands4 ,,upolu4 ,,savaii4 7,a7 7,b7 ,cleared ,land4 ,depth4 7,c7 7,d7 7,c7 7,d7 ---------------------------------------- ----------------------- ,potash#aeb 4#je 4#jdh 4#jbb 4#jfc 4#jcf 74#jg7 74#jgg7 74#jdc7 74#ajb7 74#jdc7 ---------------------------------------- ----------------------- ,lime 4#jg 4#aac 4#jcc 4#jdb 4#jbc ,magnesia 4#cg 4#bhe 4#add 4#jfg 4#jgd ,ferric ,oxid #ba4ec #ag4fjj #ai4fec #ae4ccc #ah4gcc ,alumina #ab4dj #i4fba #aa4bag #ah4ida #af4dac ---------------------------------------- ----------------------- ,silica 4#ii #b4jdc #b4hec 4#cff #a4bej ,titanic ,acid ---------------------------------------- --------------------- ,phosphoric ,acid 4#cj 4#agi 4#bac #bi4jif 4#ahg ,org4 ,matter and ,water #ah4diaecag4bhh #ab4ggj #bi4adf #af4ccb ,nitrogen in ,soil 4#cj 4#ddg 4#ahf 4#fig 4#abh ,hygr4 ,moisture #f4hj #ae4jfb #ac4bdb #ae4bhh #ab4hfb ---------------------------------------- --------------------- ,,kamerun4 ,,isongo4 ,,mundame ,,ii4 ,depth4 7,c7 7,d7 7,c7 7,d7 ---------------------------------------- ------------ ,potash#aed 4#jig 4#ajd 4#jgf 4#aaj 74#aja7 74#afc7 74#abc7 74#afh7 ---------------------------------------- ------------ ,lime 4#aic 4#aed 4#aej 4#abe ,magnesia 4#bhc #a4dae 4#aih 4#jii ,ferric ,oxid #g4cje #g4dig #ac4ibj #aa4gjg ,alumina #ad4bih #ad4ejd #e4bbc #e4eca ---------------------------------------- ------------ ,silica 4#jdg 4#ajh 4#bbg 4#abj ,titanic ,acid ---------------------------------------- ------------ ,phosphoric ,acid 4#jfd 4#bbd 4#aca 4#bje ,org4 ,matter and ,water #bc4cce #ab4bii #aj4aed #i4edi ,nitrogen in ,soil 4#ahg 4#jgi 4#afd 4#ajc ,hygr4 ,moisture #bj4jfe #ae4cbi #ad4haa #af4dih ---------------------------------------- ------------- #aeb ,the numbers in brackets are determinations made after boiling with acid for one hour4 #aec ,soil air-dry4 #aed ,the numbers in brackets are determinations made after boiling with acid for one hour4 ,it is probable that for crops requiring so much potash as do the banana and cacao trees1 potash is the first need when they cease to produce well on these soils4 ,soils of ,kamerun4--,in the soils of ,kamerun1 also analyzed by ,wohltmann1 and of which two are placed alongside of those of ,samoa1 it is at once seen that the materials from which they have been formed are richer in both potash and lime than the parent rocks of the ,samoan1 and not quite so rich in iron4 ,they are also very rich in organic matter1 evidently down to the depth of a meter1 as are those of ,samoa4 ,it is probably due to the high humus-content that these soils1 washed as they have been by the second-highest rainfall in the world 7about #ce feet annually7 have not been as thoroughly leached as have been those of the ,brahmaputra valley4 ,the annual rainfall of ,samoa is only from nine to eleven feet on the lower levels1 but ranges as high as #ah feet at higher elevations4 ,it is noticeable that in most of these true tropical soils the content of magnesia is considerably above that of lime2 a fact readily intelligible from the more ready solubility of lime in carbonated water4 ,it is hardly doubtful that this disproportion will in many cases explain a lack of thriftiness1 which could be effectually remedied by a simple application of lime or marl1 without resorting to the more costly fertilizers4 ,,the ,,soils ,,of ,,madagascar4 ,the soils of the island of ,madagascar have been analyzed to the number of about #ejj by ,mntz and ,rousseaux1 under the auspices of the ,french government4#aee ,so large a number of analyses should give a very full understanding of the agricultural capacity and adaptation of so comparatively limited an area2 unfortunately1 we are here again confronted by more or less imperfect data accompanying the samples collected by government agents1 and by the use of an analytical method different from those of all other nations1 and hence incommensurable except1 as in the case of ,wohltmann's method1 in regard to certain ingredients4 #aee ,annales de la ,science ,agronomique1 tome #a;er1 #aija1 fasicules #a1 #b1 #c4 ,the ,french chemists use nitric instead of chlorhydric acid2 cold for phosphoric acid and lime1 boiling-hot for five hours for potash2 considering the remainder as of no practical importance4 ,since nitric acid is in general much less incisive than chlorhydric in its solvent power1 comparison with the analyses made by other nations becomes difficult4 ,as in the case of ,wohltmann1 magnesia1 lime1 and phosphoric acid may be considered to be quite thoroughly extracted by the treatment2 while extraction of possibly available potash is doubtless very incomplete4 ,on the whole1 however1 the estimates of soil-fertility based on percentages is very nearly the same as those assigned by ,wohltmann in the table given above4 ,like ,wohltmann1 they emphasize the axiom that the same percentage-gauge of fertility cannot be applied in the tropics as in the temperate zones4 ,general ,character of the ,island4--,the island of ,madagascar1 lying between the #aath and #beth degrees of south latitude1 is quite mountainous in its central and eastern portion1 where the coast falls off pretty steeply into the sea1 leaving only a narrow coast belt of properly agricultural land in the lower valleys and at the mouth of the torrential streams4 ,the mountains rise at one point to the height of nearly #aj1jjj feet4 ,the western portion of the ,island is much less broken1 has much plateau land with low intersecting ranges and streams of moderate fall1 with considerable alluvial lands near the coast4 ,the rocks are almost throughout gneisses and mica-schists1 which1 as heretofore stated 7chapter #d1 p4 #ea71 form mostly poor soils4 ,there are a few areas of eruptive rocks and tertiary calcareous deposits1 and on these the lands are much more thrifty4 ,the rocks and red soils of the central mass1 however1 extend seaward almost everywhere4 ,the rainfall is high on the east side1 where the moisture of the southeast trade winds is first condensed1 the precipitation reaching ten to twelve feet 7#abj to #add inches7 annually4 ,the western portion is relatively dry1 but rains fall more or less throughout the year2 while in the eastern and central mountainous part there is a distinct subdivision into a wet and a dry season4 ,here1 while the rivers are largely torrential1 many large fertile valleys have been created by the heavy denudation of the mountain slopes4 ,this is especially the case in the ,imerina province 7in which the capital1 ,tananarivo1 is situated71 and here the valley soils are deep1 and rich in humus4 ,the western portion is but thinly forested4 ,the soils of most of the island are 8red0 with ferric hydrate1 resembling the laterite soils elsewhere2 yet the iron percentages are not usually very heavy1 ranging mostly from #d to #f1 more rarely to #aj and more1 of ferric oxid4 ,most of the red soils are clayey1 crack open in summer and become very hard in drying4 ,of the #dgf soils analyzed by ,mntz and ,rousseaux1 #aef are from the province of ,imerina1 #ef from the adjacent province of ,betsileo1 therefore #bab from the central1 mountainous part of the island4 ,the remainder are scattered around the coasts2 the most productive being apparently those of the northern end1 ,diego ,suarez1 which is mostly underlaid by the eruptive rocks forming the mountain mass of ,mount ,amber1 from which numerous fertile valleys radiate4 ,the valleys of the west coast also1 in the provinces of ,bara1 ,tulear and ,betsiriry1 have some very productive soils4 ,the subjoined table1 giving fourteen analyses selected as representative from the mass of material presented by ,mntz and ,rousseaux1 gives a fair general idea of the character of the soils of the great island4 ,it is at once apparent that lime and potash are extremely deficient in the soils of the mountain slopes of central and southern ,madagascar1 these substances having1 as elsewhere in the humid region1 been leached down into the valleys2 and the materials being mostly quite clayey1 these valley soils have not1 as in the case of the sandy alluvium of the ,brahmaputra1 themselves been again leached of their mineral ingredients4 ,practically these valleys seem to form the only profitably cultivable area of the central portion2 while along the larger river courses1 such as the ,mangoky1 ,ikopa1 ,mahajamba and others1 good alluvial 8bottoms0 and deltas form available lands4 ,it seems to the writer that1 in view of their own expressed opinion that tropical soils are not to be gauged on the same percentage-basis of soil-ingredients as those of temperate regions1 ,mntz and ,rousseaux rather underestimate the productive value of many of these lands2 regarding which the field notes report good production1 and the crops of which are certainly not the first that they have borne in the course of ,malagassy history4 ,it is as though their anxiety to forestall overestimates of agricultural prospects by intending settlers1 had led them to somewhat overshoot the mark4 ,,analyses ,,of ,,madagascar ,,soils ,,by ,,muntz ,,and ,,rousseaux4 ,,imerina4 ,,betsileo ---------------------------------------- -------------------------- ,,central ,,mountain ,,region4 ---------------------------------------- ------------------------ ,number of ,soil4 #d--d #aae #ga--d #bgb ---------------------------------------- ------------------------ ,locality ,ambohitr- ,ankazobe ,ambohib-,fandrandava omby4 ,north4 zaka4 ,valley4 ---------------------------------------- ------------------------ ,red ,soil4 ,ochreous ,soil4 ---------------------------------------- ------------------------ ,potash 7,k,o7 4#jbj 4#jjf 4#jga 4#jag ,lime 7,ca,o47 4#cej 4#jfj traces trace ,magnesia 7,mg,o47 4#jbb ,ferric ,oxid 7,fe,o7 #i4ccc ,phosphoric ,acid 7,p,o7 4#jej 4#jcb 4#jfa 4#bfg ,nitrogen 7,n7 4#jif 4#jbg 4#jcj 4#jbj ---------------------------------------- ------------------------ ,remarks ,small ,deficient in,no great ,only cultural plant-food cultural moderately resource4 ingredients4resource4 fertile4 ,may maintain vegetation on account of humidity4 ---------------------------------------- ------------------------ ,,tulear4 ,,maintirano4 ,,majunga4 ---------------------------------------- ----------------------- ,west ,coast4 ---------------------------------------- ---------------------- ,number of ,soil4 #bec #bfa ,no4 #bfg #cdc ---------------------------------------- ---------------------- ,locality ,r4 bank of ,plateau of ,village of ,sakondry ,antsoamena4 ,anhozorabe north of ,south of ,tongobory ,mandroso4 ,valley4 ---------------------------------------- ---------------------- ,sandy ,hill soil4 summit4 ---------------------------------------- ---------------------- ,potash 7,k,o7 4#jhf 4#jae 4#jad 4#jab ,lime 7,ca,o47 #d4ahj trace trace trace ,magnesia 7,mg,o47 ,ferric ,oxid 7,fe,o7 ,phosphoric ,acid 7,p,o7 4#jhc 4#jdc 4#jaa 4#jag ,nitrogen 7,n7 4#jge 4#jea 4#jci 4#jdc ---------------------------------------- ---------------------- ,remarks ,potatoes1 ,manioc1 ,remarkable,grasses1 manioc1 maize1 crops1 tall represents beans1 manioc1 herbs4 soil of peanuts1 rice4 whole coco-trees1 region4 mangoes4 ---------------------------------------- ---------------------- ,,diego ,,suarez4 ---------------------------------------- ------------ ,n4 ,,coast4 ---------------------------------------- ----------- ,number of ,soil4 #c #cca ---------------------------------------- ----------- ,locality ,anamakia4 ,montagne d',ambre4 ---------------------------------------- ----------- ,ochr'us ,ochr'us earth4 earth4 ---------------------------------------- ----------- ,potash 7,k,o7 4#afa 4#jca ,lime 7,ca,o47 4#fbj trace ,magnesia 7,mg,o47 ,ferric ,oxid 7,fe,o7 ,phosphoric ,acid 7,p,o7 4#chj 4#abd ,nitrogen 7,n7 4#abd 4#agg ---------------------------------------- ----------- ,remarks ,promises ,crops1 coffee4 considerable ,good cultural fertility4 resources4 ---------------------------------------- ----------- ,,andevorante4 ,,ambatondrazaka4 ---------------------------------------- ------------------------- ,,east ,,coast4 ---------------------------------------- ----------------------- ,number of ,soil4 #ajg #cgj #ha #aje ---------------------------------------- ----------------------- ,locality ,dist4 of ,ambaniman- ,imeriman-,sabotsy4 ,vatomandry4 hovinana4 droso4 ,ampitamafana ---------------------------------------- ----------------------- ,plain valley1 ,valley4 ,alt #ajjj sandy ,m4 soil4 ---------------------------------------- ----------------------- ,potash 7,k,o7 4#jfi 4#jab 4#dij 4#jje ,lime 7,ca,o47 4#jgj trace #a4bjj 4#jgj ,magnesia 7,mg,o47 ,ferric ,oxid 7,fe,o7 ,phosphoric ,acid 7,p,o7 4#jdg 4#afa #a4eff 4#cfi ,nitrogen 7,n7 4#jaf 4#bed 4#bdi 4#afd ---------------------------------------- ----------------------- ,remarks ,coffee1 ,very ,amply ,fertile vanilla1 fertile rich in soil fit rice1 c41 soil4 plant foodfor all rich red suited forcultures4 soil4 ,rep4 intensive whole cultures4 valley4 ---------------------------------------- ----------------------- ,be that as it may1 the influence of the tropical climate and rainfall upon the composition of these soils is certainly very marked4 ,while gneiss is not credited with producing first-class soils1 its usual content of orthoclase feldspar should at least insure a respectable average content of potash2 but this1 it will be seen1 is mostly not the case2 and that of lime seems even worse1 aside from the case where1 as in some regions near the coast 7especially in the west and south71 calcareous formations1 probably of tertiary age1 have contributed to soil-formation4 ,at some points there seem to exist phosphate deposits1 well known elsewhere to occur in such rocks1 which impart to the soils exceptionally high percentages of phosphoric acid1 even exceeding one per cent4 ,the phosphates of course remain practically untouched by the leaching processes1 and appear to be somewhat widely diffused2 so that the soils of ,madagascar may be said to be1 on the whole1 well supplied with this important plant-food4 ,in the central province of ,imerina the valleys and lower slopes show a fair content of both lime and potash2 but in the province of ,betsileo1 adjoining it on the south1 nearly every one of the soils analyzed is reported as containing only 8traces0 of lime1 together with very small amounts of potash in most cases4 ,the ultimate analyses of ignited red earths1 of which an average is here given1 are of interest in this connection4 ,,ultimate ,,analysis ,,of ,,imerina ,,red ,,soils1 ,,ignited2 ,,average ,,of ,,three4 ,silica #ee4b ,potash 4#c ,lime trace ,magnesia #a4a ,ferric oxid #aj4f ,it is quite obvious that only leaching-down and concentration of the feeble resources of such material in the valleys can produce soils worthy of permanent cultivation4 ,one point1 however1 is strikingly illustrated in several of the analyses given in the subjoined table4 ,we find in the original quite a number of cases in which the field notes report considerable fertility1 while the chemists' judgment is very unfavorable4 ,thus we find recorded for the soil ,no4 #bfg1 taken near the village of ,anjozorabe1 in the ,maintirano region1 8luxuriant vegetation and remarkable crops10 with such minute proportions of potash1 lime and phosphoric acid that the authors are compelled to say that the land offers 8no cultural resources40 ,the same occurs in the cases of soils ,nos4 #cgj1 #bfa1 and several others having either 8good crops0 or 8abundant natural vegetation40 ,unless we assume that in these cases the samples were not properly taken1 we are obliged to conclude that under the local climatic conditions1 such minute amounts of plant-food are developed with sufficient rapidity to supply good growth4 ,this would be quite parallel to the case of the tea soils of ,assam1 whose production lasted #cj years before showing exhaustion1 on plant-food percentages only slightly greater than those here noted1 and determined by a much more incisive method4 ,it is thus quite obvious that a different standard of interpretation must be applied to tropical soils as compared with either the temperate humid1 or the arid regions2 and that uniform methods of analysis are needed to evolve a definite rule from the present uncertainties4 ,,the ,,soils ,,of ,,india4 ,the soils of ,india have been investigated to some extent by the geological survey of ,india2 by ,voelcker1 who went there on a special mission to investigate agricultural conditions2 and since1 more especially by ,leather1 ,bamber and ,mann2 and by ,moreland4 ,leather's account is the most complete on the general subject and can best serve as the basis for a review of the entire peninsula4#aef #aef ,on the ,composition of ,indian ,soils4 ,agr4 ,ledger1 #ahih1 ,no4 #b4 ,according to ,dr4 ,leather1 8the four main types of soils to be dealt with1 and which certainly occupy by far the larger of the ,indian cultivated area10 are3 ,the ,indo-,gangetic alluvium1 covering the chief cultivable areas of the ,indo-,gangetic plain2 the black cotton soils or regur1 occupying the main body of the plateau of the ,central provinces 7the ,deccan7 from the ,vindhya range south2 the red soils lying on the metamorphic rocks of ,madras2 and the 8laterite0 soils which are met with in many parts of ,india4 ,to these should be added the alluvial soils of the ,brahmaputra valley1 in ,assam4 ,it is hardly to be expected that so large an area as that of ,india1 with its diversified topography1 and a climate ranging from about four inches of rainfall in the northern ,panjab to the world's maximum in ,assam1 and southward to typical tropical conditions1 could be even thus briefly characterized4 ,the observers have rarely given for the several soils analyzed1 special local and climatic data1 which cannot always be obtained from the official publications2 so that it is not easy to discuss them from the points of view of aridity and humidity4 ,the ,indo-,gangetic ,plain4--,the general rain-map of ,india shows the ,panjab and ,rajputana to be arid throughout2 thence eastward the rainfall increases to #be and #cj inches on the ,ganges2 notwithstanding which1 alkali 7reh7 is abundant about ,aligarh1 ,meerut and ,agra4 ,thence toward ,calcutta there is a steady increase of rainfall until1 at the head of the ,bay of ,bengal1 #gj inches is reached4 ,if under these conditions the ,indo-,gangetic plain admits of any generalizations as regards soil composition1 it must be attributed in the main to its predominantly alluvial character4 ,it should therefore be relatively rich in lime1 magnesia and potash4 ,so far as the first is concerned1 ,leather remarks that the only rocky particles larger than sand to be found in all this large belt of land is the nodular limestone called kankar1 formed by the deposition of calcium carbonate within the soil1 at the depth of a few feet4 ,it occurs very generally in ,india1 and as stated above 7chapters #i and #ai71 this occurrence of calcareous hardpan1 of varying hardness1 is almost universal in the arid regions4 ,the analysis given in the table1 selected as representative from those given by ,leather1 show that the general forecast is realized in them1 as soils of an arid region4 ,,analyses ,,of ,,soils ,,of ,,india4 ,,northern ,,india4 ,indo-,gangetic ,alluvium4 -------------------------------- ,panjab4 ,lower ,ganges4 ------------------------------ ,sotar ,changa ,ison1 ,sibpur1 ,valley4,manga4 ,ganges1,calcutta ,clay ,loamy ,doab4 ,clay ,loam4 soils4 ,sandy soils4 #aeg ,loams4 ---------------------------------------- ----------------- ,insoluble matter #ha4eg #ha4ed #hh4jh #gc4eh ,soluble silica ---------------------------------------- ------------------ ,potash 7,k,o7 4#gd 4#ed 4#fd ,soda 7,na,o7 4#jh 4#be 4#ji #a4hb ---------------------------------------- ------------------ ,lime 7,ca,o7 #a4dd 4#ih 4#dg #a4ja ,magnesia 7,mg,o7 #a4ig #a4gb 4#cb #a4fd ,br4 ox4 of ,manganese 7,mn,o7 4#aa #g4ai ,peroxid of iron 7,fe,o7 #d4cb #e4aa #c4aj #g4eh ,alumina 7,al,o7 #e4he #d4cf #d4ch #i4hi ,phosphoric acid 7,p,o7 4#bc 4#ad 4#jh 4#jg ,sulfuric acid 7,,so7 8 4#jb 4#je 4#jj ,carbonic acid 7,,co7 #a4ac 4#de 4#cg 4#bh ,water and org4 matter #b4fg #d4gh #b4db #e4ic ------------------------------ ,total #ajj4jj #ajj4jj #ajj4jj #ajj4jj ,nitrogen 4#jb 4#jhb 4#jbg 4#jea ---------------------------------------- ------------------ ,brahmaputra ,alluvium4 --------------------------------------- ,assam4#aeh ------------------------------------ ,fezpur ,lakhimpur,golaghat4 ,sipsagar bank4 ,new ,nigriling4 ,teela ,old ,alluvium4 ,new land4 ,alluvium4 ,alluvium4 ,new ,alluvium ---------------------------------------- ------------------------ ,insoluble matter #he4ah #hd4fj #he4hh #ia4eb ,soluble silica ---------------------------------------- ------------------------ ,potash 7,k,o7 4#ce 4#bd 4#bf 4#ad ,soda 7,na,o7 4#cj 4#ab 4#bc 4#af ---------------------------------------- ------------------------ ,lime 7,ca,o7 4#jd 4#aa 4#jc 4#jf ,magnesia 7,mg,o7 4#df 4#cc 4#cf 4#bj ,br4 ox4 of ,manganese 7,mn,o7 ,peroxid of iron 7,fe,o7 #b4jh #b4gh #b4gd #a4eb ,alumina 7,al,o7 #e4jc #e4fc #e4aj #c4cj ,phosphoric acid 7,p,o7 4#je 4#jf 4#jf 4#jf ,sulfuric acid 7,,so7 4#jb 4#jb 4#jb 4#jb ,carbonic acid 7,,co7 ,water and org4 matter #e4ei #f4aa #e4cb 4#ah ------------------------------------ ,total ,nitrogen 4#ad 4#bj 4#ah 4#jh ---------------------------------------- ------------------------ ,laterite ,soils4 ------------------------------- ,bengal4 ----------------------------- ,lohardaga4 ,chota ,hazaribagh ,nagpur4 ,district4 ,singhbhum ,district4 ---------------------------------------- ----------------- ,insoluble matter #bi4fg #ei4jf #hj4df ,soluble silica ---------------------------------------- ----------------- ,potash 7,k,o7 4#aj 4#bg 4#ch ,soda 7,na,o7 4#jd 4#cb ---------------------------------------- ----------------- ,lime 7,ca,o7 4#ch 4#bh #a4gb ,magnesia 7,mg,o7 4#ba 4#cc 4#ch ,br4 ox4 of ,manganese 7,mn,o7 4#jg 4#dh 4#ej ,peroxid of iron 7,fe,o7 #dh4ga #bf4fd #f4ab ,alumina 7,al,o7 #h4ha #g4bg #g4ai ,phosphoric acid 7,p,o7 4#fd 4#jh ,trace4 ,sulfuric acid 7,,so7 ,trace4 ,carbonic acid 7,,co7 4#jf 4#af 4#ab ,water and org4 matter #aa4ca #e4dc #b4ha ----------------------------- ,total #ajj4jj #ajj4jj ,nitrogen 4#jaj 4#jbd 4#jc ---------------------------------------- ----------------- #aeg ,analysis by ,voelcker4 #aeh ,analyses by ,mann4 ,,southern ,,india4 ,madras ,presidency4 ---------------------------------------- ------------------- ,laterite ,upland4 ,soil4 ,red ,soils4 ------------------------------ ,sidapet4 ,madura4 ,trichinopoli4 ,dindigal4 ,parambalur4 ---------------------------------------- ------------------ ,insoluble matter #gf4hf #ij4dg #hf4gd ,soluble silica ---------------------------------------- ------------------ ,potash 7,k,o7 4#ji 4#bd 4#je ,soda 7,na,o7 4#ag 4#ab 4#ae ---------------------------------------- ------------------ ,lime 7,ca,o7 ,trace4 4#ef 4#dh ,magnesia 7,mg,o7 4#gg 4#gj 4#gj ,br4 ox4 of ,manganese 7,mn,o7 4#ai 4#jh 4#aj ,peroxid of iron 7,fe,o7 #aj4ji #c4ea #e4gj ,alumina 7,al,o7 #h4hd #b4ib #e4fh ,phosphoric acid 7,p,o7 ,trace4 4#ji 4#je ,sulfuric acid 7,,so7 ,carbonic acid 7,,co7 4#ab 4#cj 4#aa ,water and org4 matter #b4hg #a4ja 4#bd ------------------------------ ,total #ajj4jj #ajj4jj #ajj4jj ,nitrogen 4#jae 4#jjf 4#jba ---------------------------------------- ----------------- ,madras ,presidency4 ---------------------------------------- -------------------------- ,alluvium4 ,regur4 ,averages4 ----------------------------------- ,loamy ,sandy ,regur4 ,trichin- ,kistina ,soils4,soils4 ,avg4 opoli4 #ah ,parambalur,narsa- ,soils4 ,taluk4 opet4 ---------------------------------------- ----------------------- ,insoluble matter #ga4gi #ic4ji #fh4da #fe4af #fh4bi ,soluble silica ---------------------------------------- ----------------------- ,potash 7,k,o7 4#bb 4#jd 4#da 4#ad #a4ad ,soda 7,na,o7 4#ag 4#jg 4#ca 4#ja #a4cj ---------------------------------------- ----------------------- ,lime 7,ca,o7 4#ed 4#ac #b4ij #b4ah #c4dc ,magnesia 7,mg,o7 #a4bi 4#cc #b4bg #b4dg #a4id ,br4 ox4 of ,manganese 7,mn,o7 4#ac 4#jd 4#ag 4#be 4#ji ,peroxid of iron 7,fe,o7 #i4ei #b4df #g4ac #i4bg #f4if ,alumina 7,al,o7 #i4ih #a4gd #aj4ad #ac4gf #aj4bh ,phosphoric acid 7,p,o7 4#aa 4#je 4#jf ,trace4 4#jj ,sulfuric acid 7,,so7 ,trace4 ,trace4 ,carbonic acid 7,,co7 4#ji 4#aa #a4fb 4#ia #a4hh ,water and org4 matter #f4ji #a4id #f4eh #e4he #c4if ----------------------------------- ,total #ajj4jjajj4jjajj4jj #ajj4jj #ii4bg ,nitrogen 4#jcg 4#jae 4#jc 4#jbd 4#jab ---------------------------------------- ----------------------- ,the ,brahmaputra ,alluvium in ,assam4--,aside from the immediate alluvium of the ,indus1 of which no definite data are available1 the ,indo-,gangetic plain represents the drainage of the southern slope of the ,himalaya chain4 ,that of most of the northern slope is represented by the ,brahmaputra1 which not only originates in a region of heavy precipitation--,thibet--but continues in the same throughout its course1 and rounding the easternmost spur of the ,himalaya range enters1 in southern ,assam1 upon the region of the maximum rainfall known4 ,its alluvial deposits should therefore show the reverse characteristics of those of the ,ganges2 they should1 as thoroughly leached soils1 be poor in lime1 magnesia and potash4 ,we have fortunately on this subject the excellent work done by ,mr4 ,h4 ,h4 ,mann for the ,indian ,tea ,association1 the report of which was published in #aija1 and contains1 besides a large number of analyses1 good descriptions of the general soil and cultural conditions of the ,assam tea districts1 with suggestions for their improvement4 ,the tea plantations of ,assam are located almost wholly on the new and old alluvium of the ,brahmaputra river1 bordered on the north by the eastern spur of the ,himalayas1 on the south by the low ranges of the ,khasia hills4 ,the soil is mostly quite sandy1 the late alluvium gray in color1 the older reddish and more loamy4 ,of the four analyses given in the table and fairly representing the average character of these soils1 the two first are from the north side1 the latter two from the south side of the river4 ,it will be noted that the prominent feature of all these soils is an extremely low percentage of lime1 the general average being about 4#jh as against nearly #a4j in the average ,indo-,gangetic soils4 ,in the latter1 potash ranges between 4#fe and 4#gj2 in the ,assam soils between 4#be and 4#ce4 ,magnesia averages nearly #a4c in the ,indo-,gangetic1 against about 4#ej in the ,assam tea soils4 ,it is thus apparent that the same general facts as regards the leaching-out of soil ingredients already shown for eastern and western ,north ,america are strikingly verified in northern ,india2 but reversed as regards the points of the compass4 ,the preferential leaching-out of lime as compared with magnesia and potash1 is here again well exemplified4 ,it would be interesting to have an analysis of the ,brahmaputra water to compare with that of the ,ganges4 ,that tea should flourish for twenty to thirty years in such soils1 is a good indication of one cause at least of the total failure of tea culture in ,california1 where tea plants are difficult to maintain alive1 and after #be years form rounded1 scrubby bushes not over four feet high4 ,similar failures of tea on calcareous soils are on record from ,india4 ,the low lime-content of the ,assam soils1 then1 does not necessarily imply that these soils should be limed to maintain tea production4 ,according to ,mann1 the main deficiency is in nitrogen1 as the figures imply2 but whether his recommendation of green-manuring with leguminous crops to increase the nitrogen-supply is practicable without first supplying more lime to the ,assam soils1 is questionable4 ,since phosphoric acid is also low1 his recommendation to use freely the basic or ,thomas slag is doubtless a good one1 since lime would thus also be moderately increased4 ,bamber gives a number of analyses of tea soils from low ground in ,assam1 which are very rich in vegetable matter and quite acid4 ,like those reported by ,leather1 these 8bhil0 soils are very poor in lime and nitrogen1 but fairly supplied with potash and phosphoric acid4 ,the ,regur or ,black ,cotton ,soils of ,southern ,india4--,the second-greatest reasonably uniform soil-area of ,india is that covered by the regur1 or black cotton soils1 in south central ,india1 notably the ,deccan1 where these soils are said to have been cultivated without fertilization for #bjjj years and are still fairly productive4#aei ,both in their physical character1 chemical composition1 and cultural characteristics1 these regur soils are very similar to the 8prairie soils0 of the ,cotton states and especially to the 8black adobe0 of ,california4 ,like the latter they are of unusual depth without change of tint2 they crack wide open during the dry season on account of their high clay content2 and the soil is thus partly inverted by the surface soil falling into the cracks4 ,to the latter fact ,leather ascribes1 in part1 the long duration of fertility in the regur lands4 ,the regur also contains fragments of calcareous hardpan 7here called guvarayi71 just as in the ,great ,valley of ,california4 ,the eighteen analyses of regur given by ,leather agree so nearly in their essential points that it is admissible to average them2 two other examples are however also given in the table4 #aei ,that is to say1 they now produce about #fjj pounds1 or #aj bushels of wheat per acre1 as do the ,rothamstead soils after fifty years' exhaustive cultivation4 ,probably both have come down to the permanent level of production corresponding to the amount of plant-food made currently available each year by the fallowing process in originally very rich soils4 ,the present product of cotton on the regur lands does not seem to be on record2 judging by the wheat product it should not be over one hundred pounds of lint per acre4 ,it will be noted that while the contents of lime1 magnesia and alumina are uniformly high1 the content of potash has a wide range2 it rises very high 7#a4ad7 in the maximum1 while the average is fair4 ,one conspicuous defect of these soils is their extremely low content of nitrogen1 in view of which their lasting productiveness is difficult to understand2 unless it be that1 as in ,california1 their high lime-content causes a copious crop of leguminous weeds1 constantly replacing the nitrogen supply4#afj ,unfortunately we have no determinations of humus or of its nitrogen-content4 ,leather attributes the black color of the regur to some mineral substance rather than to humus2 but his arguments are not quite convincing1 so long as the ,grandeau test has not been made4 ,in view of the low rainfall and the closeness of the texture of regur1 it is probable that little if any nitrates are currently washed out of the black cotton lands4 #afj ,see ,voelcker1 ,report on the ,improvement of ,indian ,agriculture1 #ahib1 p4 #df1 par4 #fj4 ,the regur soil-sheet seems to be underlaid over the greater part of its area by a basaltic eruptive sheet 7not by metamorphic rocks1 as stated by ,leather71 and it is not easy to conceive how such a soil stratum can have been formed from such rocks as a sedentary formation4 ,elsewhere such soils are usually rather light and porous1 as is the case in the ,hawaiian and ,samoan islands2 and very high in iron-content4 ,the regur has the character of an alluvial backwater or lake deposit2 but how such a formation can have occurred on the ,deccan plateau1 is a question not easily answered4 ,red ,soils of the ,madras ,region4--,interspersed with and to seaward of the regur lands there are in the ,madras presidency considerable bodies of 8red0 lands1 which appear to be sedentary soils formed from underlying dark-colored1 mostly eruptive rocks4 ,some of these are very rich in lime and potash1 others very poor1 and it seems impossible to classify them under any definite category either from the chemical or physical point of view1 except as to their red tint4 ,even this tint1 however1 is not always found associated with exceptionally high contents of iron oxid1 but due rather to its fine diffusion in the soil mass4 ,as compared with the regur1 with which the 8red 0 areas are interspersed1 these soils contain1 on the average1 less lime1 potash and ferric oxid2 and phosphoric acid is uniformly low4 ,the alluvial 7brown and black7 soils from the same region1 exemplified in the table1 are doubtless derived partly from the regur1 and their color and composition varies accordingly4 8,laterite ,soils40--,these are defined by ,wohltmann 7,tropische ,agricultur1 #ahib7 as being 8the characteristic sedentary soils 7,verwitterungsbden7 of the tropics1 formed under the influence of heavy precipitation1 high temperatures and drought40 ,this definition does not indicate their derivation from any particular rock1 such as laterite is supposed to be2 but its definition puzzles even geologists1 and so1 as ,leather observes1 the definition of laterite soils will naturally puzzle agricultural chemists4 ,accordingly it is difficult to deduce from the analyses given any definite common characters4 ,leather describes those analyzed by him as red or reddish1 sandy and gravelly1 the gravel or cobbles often incrusted with a dark-smooth crust of limonite1 which to the uninitiated looks as though the rock itself had been fused and vitrified4 ,the samples from ,lohardaga and ,singhbhum show the effects of these limonite crusts upon the composition of the soils1 which resembles that of the ,hawaiian soils mentioned above2 but in the latter the iron oxid is wholly pulverulent4 ,but it is probable that1 as in the case of the latter1 the high content of phosphoric acid shown in the statement 74#fd for the ,lohardaga soil7 is tightly locked up in the insoluble form of ferric phosphate4 ,wohltmann's definition of laterite soils seems best represented by the 8terra roxa0 of ,brazil1 which as he states has 4#jb to4#jh of potash1 4#jb to4#aj of lime1 and 4#jde to 4#aj of phosphoric acid4 ,humus and nitrogen are very deficient in all these soils4 ,while most prominent in the coast region of ,bengal1 they also occur not only near ,madras 7,saidapet7 but also in the belt of high rainfall on the ,malabar 7western7 coast of the ,indian peninsula4 ,the productiveness of the laterite soils seems throughout to be only moderate1 yet much higher than would be expected of soils of similar composition in the temperate zones1 where the rate of soil-formation is so much slower than in the tropics4 ,from the analyses of 8coffee soils0 from ,yarcand in the ,sheveroy hills1 north of ,madras1 we learn that coffee does well with a fairly liberal supply of lime 74#cj to4#dd7 and phosphoric acid1 but is satisfied with a much smaller amount of potash than is found in the tea soils of ,assam4 ,a farther systematic investigation of the soils of ,india1 with simultaneous accurate observations on their depth1 subsoil1 geological derivation1 topographical location and relations to rainfall1 could not fail to yield very important practical results4 ,the examination of samples collected and sent in by persons unfamiliar with the proper mode of taking soil specimens1 and the information which should accompany them1 always involves a great deal of uncertainty and waste of labor1 and indefiniteness of results4 ,,influence ,,of ,,aridity ,,upon ,,civilization4 ,in connection with the facts given and discussed above1 as to the relative productive capacity of lands of the humid and arid regions1 it becomes of interest to consider what influence1 if any1 these differences may have had in determining the choice of the majority of the ancient civilizations in favor of countries where nature imposes upon the husbandman1 who supplies the prime necessaries of life1 the onerous condition of artificial irrigation4#afa #afa ,verhandlungen der ,deutschen ,physiologischen ,gesellschaft in ,berlin1 ,december1 #ahib2 ,north ,american ,review1 ,september1 #aijb4 ,preference of ,ancient ,civilizations for ,arid ,countries4--,a brief review suffices to establish the fact of such choice4 ,aside from ,egypt1 the permanent fertility of which is ascribed to the inundations of the ,nile1 we find to westward the oases of the ,libyan and ,sahara deserts1 the high fertility of which has become proverbial and has caused them to be cultivated from ancient times to the present4 ,similarly1 on both sides of the ,mediterranean ,sea1 we find that1 instead of the humid forest country1 it was in the arid but irrigable coast countries1 such as the vegas of ,valencia1 ,alicante1 ,granada1 ,malaga1 and the even more arid domain of which ,carthage was the metropolis2 and farther east1 in the ,graeco-,syrian archipelago and the adjacent coasts1 that noted centers of civilization were developed and maintained4 ,thence the arid belt requiring irrigation extends from ,egypt and ,arabia to ,palestine1 ,syria1 ,assyria1 ,mesopotamia and ,persia1 and across the ,indus through the anciently recognized regions of ,indian civilization--,sindh1 the ,panjab1 ,rajputana and the ,northwestern provinces--to the ,ganges1 embracing such well-known centers as ,lahore1 ,delhi1 ,meerut1 ,agra1 etc41 inhabited by much more hardy and progressive races than the humid and highly productive tropical portions of the ,indian peninsula4 ,throughout the extensive and important portion of northern ,india1 irrigation is necessary to maintain regular production2 and in default of it1 periodic famines ravage the country4 ,thousands of years ago1 millions upon millions of treasure were expended there upon irrigation works1 as has again been done in modern times2 yet in the rainy1 forested districts we still find large areas practically tenanted by wild beasts4 ,in ,asia ,minor1 as well as in ,central ,asia1 the remains of ancient cities once surrounded by richly productive irrigated fields1 are found where at present only the herds of nomads pasture4 ,the ,khanates of southern ,turkestan with their historic cities1 illustrate the same obstinate bias in favor of arid climates4 ,similarly1 in the ,new ,world1 it was not in the moist and exuberantly fertile forest lands of the ,orinoco and ,amazon1 but on the arid western slopes of the ,andes1 that the civilization of the ,incas was developed4 ,in ,mexico1 also1 it was the high central1 arid plateau1 not the bountifully productive tierra caliente1 over which the ,aztecs chose to establish the main centers of their empire4 ,even to northward1 the inhabitants of the high1 dry plains of ,arizona and ,new ,mexico were1 as their descendants of the ,pueblos are to-day1 superior in social development to their forest-dwelling neighbors of the ,algonquin race4 ,from time immemorial they have practiced irrigation in connection with cultivation1 maintaining a comparatively dense population on very limited areas4 ,it might be thought that the desire to avoid the labor of clearing the forest ground was the motive which guided the choice of the ancient nations toward the cheerless-looking1 treeless regions4 ,but if we consider the cost and labor of establishing and maintaining irrigation ditches1 it certainly seems that a stronger motive1 based on the intrinsic nature of the case1 must have influenced their selection4 ,neither can we with any degree of plausibility ascribe the preference for the arid open country to the fear of enemies lurking in the forest1 since war was in early times practically the normal condition of mankind1 and was waged with little hesitation wherever booty was in sight4 ,it has also been asked how the ancients could have known of the high productive capacity of arid lands2 but no one who has ever seen the springing-up of luxuriant vegetation after the periodic overflows of the arid-region streams1 or the same surrounding the springs in the deserts1 would ask that question4 ,irrigation necessitates ,co-operation4--,irrigation enterprises can be accomplished in a very limited degree only by individuals or even families4 ,its permanently successful execution requires the co-operation of at least several social groups1 ultimately of communities and states1 if it is not to give rise to acrimonious contentions or actual warfare2 witness the 8shotgun policy0 resorted to in the arid ,west in times not very remote4 ,irrigation1 in other words1 compels co-operative social organization quite different from and far in advance of that necessary in humid countries4 ,and such organization is manifestly conducive to the preservation and development of the arts of peace1 which means civilization4 ,the most ancient systematic code of laws known to us is that of ,hammurabi1 the king of arid ,assyria4 ,the high and permanent productiveness of arid soils induces permanence of civil organization4--,in humid countries1 as is well known1 cultivation can only in exceptional cases be continued profitably for many years without fertilization4 ,but fertilization requires a somewhat protracted development of agriculture to be rationally and successfully applied in the humid regions1 and the ,germanic tribes1 like the ,north-,american ,indians1 seem to have shifted their culture grounds frequently in their migrations4 ,no such need was felt by the inhabitants of the arid regions for centuries1 for the native fertility of their soils1 coupled with the fertilizing effects of irrigation water bringing plant-food from afar1 relieved them of the need of continuous fertilization2 while in the humid regions1 the fertility of the land is currently carried into the sea by the drainage waters1 through the streams and rivers1 causing a chronic depletion which has to be made up for by artificial and costly means4 ,what with the greater intrinsic fertility and the great depth of soil available for plant growth1 much smaller units of land will suffice for the maintenance of a family in arid countries2 a fact which is even now being illustrated in the irrigated region of the ,united ,states1 where ten acres of irrigated land instead of #dj or #afj1 as in the ,east1 form the unit4 ,the arid regions were1 therefore1 specially conducive to the establishment of the highly complex polities and high culture1 of which the vestiges are now being unearthed in what we are in the habit of calling 8deserts20 the very sands of which usually need only the life-giving effects of water to transform them into fruitful fields and gardens4 ,it is also quite natural that the wealthy and prosperous communities so formed should in the course of time have excited the cupidity of the 8barbarous0 forest-inhabiting races1 and as history records1 have been over and again overwhelmed by them--a similar fate often afterwards overtaking the conquerors in their turn1 after the ,capuan ease of their existence had weakened their warlike prowess4 ,at the present time1 the arid regions of the old world are still largely suffering from having been overrun by the nomadic ,turanians1 whose original habitat--,mongolia and ,turkestan--while also arid1 does not permit of the ready realization of the advantages above outlined1 on account of the rigorous climate brought about by altitude4 ,mahometanism first expelled1 and has since repelled1 occidental civilization from the arid regions of the ,old ,world1 remaining to-day as an obstacle to its progress4 ,the peaceful aggression of railroads and telegraphs now seems likely to gradually overcome this repulsion2 and when ,constantinople and ,bagdad shall be linked together by the steel bands1 the desert will lose its terrors1 and ,mesopotamia and ,babylonia will again become garden lands1 as of old1 under the abundant waters of the ,euphrates and ,tigris4 ,until the water-supplies of the arid countries shall have been more definitely gauged1 it is impossible to foretell to what extent food-production may be increased by their cultivation under irrigation1 after the relief from political misrule shall have rendered such undertakings safe4 ,but it can even now be foreseen that with improved modern methods of cultivation1 the productive area of the world can be vastly increased by the utilization of the countries where1 as the ,turcomans say1 8the salt is the life of the land40 ,,chapter ,,xxii4 ,,alkali ,,soils4 ,alkali ,lands and ,seashore ,lands4--,alkali lands proper1 as already stated1 are wholly distinct in their nature and origin from the salty lands of sea-coast marshes1 past or present4 ,the latter derive their salts from sea-water that occasionally overflows them1 or from that which has evaporated in segregated basins or estuaries2 and the salts impregnating them are essentially 8sea salts10 that is1 common salt1 together with bittern 7magnesium chlorid71 ,epsom salt 7magnesium sulfate7 gypsum1 etc4 7see chapter #b1 p4 #bf74 ,very little of what would be useful to vegetation or desirable as a fertilizer is contained in the salts impregnating such soils2 and they are by no means always intrinsically rich in plant-food1 but vary greatly in this respect4 ,while seashore lands are by no means always of high fertility even when freed from their salts1 especially when very sandy1 it is otherwise when they occur near the mouths of streams or rivers1 whose finest sediments they then receive4 ,from such lands are formed the profusely productive ,polders of ,holland and northern ,germany1 and the equally noted 8colmates0 of ,france and ,italy4 ,these1 so soon as freed from salt1 may be considered as possessing the same advantages as 8delta0 alluvial lands1 and from the same causes2 notably the accumulation of the finest sediments derived from the rivers' drainage basins4 ,origin4--,alkali lands proper bear no definite relation to the present sea2 they are mostly remote from it or from any other sea bed1 so that they have sometimes been designated as 8terrestrial salt lands40 ,their existence is in the majority of cases definitely traceable to climatic conditions alone4 ,they are the natural result of a light rainfall1 insufficient to leach out of the land the salts that always form in it by progressive weathering of the rock powder of which all soils largely consist4 ,where the rainfall is abundant1 that portion of the salts corresponding to 8sea salts0 is leached out into the bottom water1 and with this passes through springs and rivulets into the country drainage1 to be finally carried to the ocean4#afb ,another portion of the salts formed by weathering1 however1 is partially or wholly retained by the soil2 it is that portion chiefly useful as plant food4 #afb ,see ,chapter #b1 p4 #bf4 ,it follows that when1 in consequence of insufficient rainfall1 all or most of the salts are retained in the soil1 they will contain not only the ingredients of sea-water1 but also those useful to plants4 ,in rainy climates a large portion even of the latter is leached out and carried away4 ,in extremely arid climates1 on the contrary1 the entire mass of the salts remains in the soils2 and1 being largely soluble in water1 evaporation during the dry season brings them to the surface1 where they may accumulate to such an extent as to render ordinary useful vegetation impossible2 as is seen in 8alkali spots10 and sometimes in extensive tracts of 8alkali desert40 ,three compounds1 viz4 the sulfate1 chlorid and carbonate of sodium1 usually form the main mass of these saline efflorescences4 ,magnesium sulfate 7,epsom salt7 is in many cases a very abundant ingredient2 some calcium sulfate is nearly always present1 and calcium chlorid is not infrequently found4 ,in some cases the above salts are in part at least derived from the leaching of adjacent or subjacent geological deposits impregnated with them at the time of their formation4 ,such is the case in portions of ,wyoming1 ,colorado and ,new ,mexico1 in the ,colorado river delta1 and in the ,hungarian ,plain2 and it is in these cases especially that the chlorids of calcium and magnesium also form part of the saline mixture4 ,geographical ,distribution of ,alkali ,lands4--,in looking over a rainfall map of the globe#afc we see that a very considerable portion of the earth's surface1 forming two belts to poleward of the two tropics1 has deficient rainfall2 the latter term being commonly meant to imply any annual average less than #bj inches 7#ejj millimeters74 ,the arid region thus defined includes1 in ,north ,america1 most of the country lying west of the one hundredth meridian up to the ,cascade ,mountains1 and northward beyond the line of the ,united ,states2 southward1 it reaches far into ,mexico1 including especially the ,mexican plateau4 ,in ,south ,america it includes most of the ,pacific ,slope 7,peru and ,chile7 south to ,araucania2 and eastward of the ,andes1 the greater portion of the plains of western ,brazil and ,argentina4 ,in ,europe only a small portion of the ,mediterranean border is included2 but the entire ,african coast-belt opposite1 with the ,saharan and ,libyan deserts1 ,egypt and ,arabia1 are included therein1 as well as1 south of the ,equator1 a considerable portion of ,south ,africa 7,kalahari desert74 ,in ,asia1 ,asia ,minor1 ,syria 7with ,palestine71 ,mesopotamia1 ,persia1 and northwestern ,india up to the ,ganges1 and northward1 the great plains or steppes of central ,asia eastward to ,mongolia and western ,china1 fall into the same category2 as does also a large portion of the ,australian continent4 #afc ,see above1 chapter #af1 p4 #bid4 ,utilization of ,world-wide ,importance4--,over these vast areas alkali lands occur to a greater or less extent1 the exceptions being the mountain regions and adjacent lands on the side exposed to the prevailing winds4 ,it will therefore be seen that the problem of the utilization of alkali lands for agriculture is not of local interest only1 but is of world-wide importance4 ,it will also be noted that many of the countries referred to are those in which the most ancient civilizations have existed in the past1 but which at present1 with few exceptions1 are occupied by semi-civilized people only4 ,it is doubtless from this cause that the nature of alkali lands has until lately been so little understood1 that even their essential distinctness from the sea-border lands has been but recently recognized in full4 ,moreover1 the great intrinsic fertility of these lands when freed from the noxious salts1 has been very little appreciated2 their repellent aspect causing them to be generally considered as permanently waste lands4 ,repellent aspect4--,this aspect is essentially due to their natural vegetation being in most cases confined to plants useless to man1 commonly designated as 8saline vegetation10#afd of which but little is usually relished by cattle4 ,notable exceptions to this rule occur in ,north and ,south ,america1 ,australia1 and ,africa1 where the 8saltbushes0 of the former and the 8karroo0 vegetation of the latter form valuable pasture and browsing grounds4 ,apart from these1 however1 all efforts to find culture plants for these lands generally acceptable1 or at least profitable1 in their natural condition1 have not been very successful4 #afd ,see ,chapter #bc4 ,illustration3 ,,fig4 #fj4--;,alkali ,lands in ,san ,joaquin ,valley1 ,california4 ,figure #fj illustrates the usual aspect of alkali lands in the ,san ,joaquin valley of ,california4 ,it will be noted that the alkali-covered surface is only in spots1 with clumps of vegetation between1 so that cattle can find both pasture and browsing on a portion of such lands1 even though the plants so growing are not usually of the most desirable kind4 ,we find in all arid regions1 however1 considerable areas either wholly destitute of vegetation1 or bearing only such saline growth as is rejected by all kinds of domestic animals4 ,effects of ,alkali upon culture plants4--,in land very strongly impregnated with alkali salts1 most culture plants1 if their seed germinates at all1 will show a sickly growth for a short time1 8spindle up0 and then die without fruiting4 ,in soils less heavily charged the plants may simply become dwarfed1 and fruit scantily4 ,the effect on grown trees around which alkali has come up1 is first1 scanty leafage and short growth of shoots1 themselves but sparsely clothed with leaves4 ,this state of things is well shown in figures #fa and #fb1 which represent apricot trees growing but a short distance apart1 but one coming within range of an expanding alkali spot4 ,the characteristic sparseness of the foliage of the 8alkalied0 tree as compared with the adjacent one is well shown4 ,nature of the injury to plants from ,alkali4--,when we examine plants that have been injured by alkali1 we will mostly find that the visible damage has been done near the base of the trunk1 or root crown2 rarely at any considerable depth in the soil itself4 ,in the case of green herbaceous stems1 the bark is found to have been turned to a brownish tinge for half an inch or more1 so as to be soft and easily peeled off4 ,in the case of trees1 the rough bark is found to be of a dark1 almost black1 tint1 and the green layer underneath has1 as in the case of herbaceous stems1 been turned brown to a greater or less extent4 ,in either case the plant has been practically 8girdled10 the effect being aggravated by the diseased sap poisoning more or less the whole stem and roots4 ,the plant may not die1 but it will be quite certain to become unprofitable to the grower4 ,illustration3 ,,fig4 #fa4--,unaffected4 ,illustration3 ,,fig4 #fb4--,yielding to ,alkali4 ,,apricot ,,trees ,,on ,,alkali ,,ground4 ,it is mainly in the case of land very heavily charged with common salt1 as in the marshes bordering the sea1 or salt lakes1 that injury arises from the direct effects of the salty soil-water upon the feeding roots themselves4 ,in a few cases the gradual rise of salt water from below in consequence of defective drainage1 has seriously injured1 and even destroyed1 old orange orchards4 ,the natural occupancy of the ground by certain native plants may be held to indicate that the soil is too heavily charged with saline ingredients to permit healthy root growth or nutrition until the excess of salts is removed4 7,see below1 chapters #bc and #bf74 ,the fact that in cultivated land the injury is usually found to occur near the surface of the soil1 concurrently with the well-known fact that the maximum accumulation of salts at the surface is always found near the end of the dry season1 indicates clearly that this accumulation is due to evaporation at the surface4 ,the latter is often found covered with a crust consisting of earth cemented by the crystallized salts1 and later in the season with a layer of whitish dust resulting from the drying-out of the crust first formed4 ,it is this dust which becomes so annoying to the inhabitants and travelers in alkali regions1 when high winds prevail1 irritating the eyes and nostrils and parching the lips4 ,effects of ,irrigation4--,one of the most annoying and discouraging features of the cultivation of lands in alkali regions is that1 although in their natural condition they may show but little alkali on their surface1 and that mostly in limited spots1 these spots are found to enlarge rapidly as irrigation is practiced4 ,yet since alkali salts are the symptoms and result of insufficient rainfall1 irrigation is a necessary condition of agriculture wherever they prevail4 ,under irrigation1 neighboring spots will oftentimes merge together into one large one1 and at times the entire area1 once highly productive and perhaps covered with valuable plantations of trees or vines1 will become incapable of supporting useful growth4 ,this annoying phenomenon is popularly known as 8the rise of the alkali0 in the western ,united ,states1 but is equally well known in ,india and other irrigation regions4 ,the soil being impregnated with a solution of the alkali salts1 and acting like a wick1 the salts naturally remain behind on the surface as the water evaporates1 the process only stopping when the moisture in the soil is exhausted4 ,we thus not infrequently find that after an unusually heavy rainfall there follows a heavier accumulation of alkali salts at the surface1 while a light shower produces no perceptible permanent effect4 ,we are thus taught that1 within certain limits1 the more water evaporates during the season the heavier will be the rise of the alkali2 provided that the water is not so abundant as to leach the salts through the soil and subsoil into the subdrainage4 ,leaky ,irrigation ditches4--,worst of all1 however1 is the effect of irrigation ditches laid in sandy lands 7such as are naturally predominant in arid regions71 without proper provision against seepage4 ,the ditch water then gradually fills up the entire substrata so far as they are permeable1 and the water-table rises from below until it reaches nearly to the ditch level2 shallowing the subsoil1 drowning out the deep roots of all vegetation1 and bringing close to the surface the entire mass of alkali salts previously diffused through many feet of substrata4 ,surface and ,substrata of ,alkali ,lands4--,aside from the desert proper1 in the greater portion of the alkali country 8alkali spots40 i4 e4 ground covered with saline efflorescences and showing little or no vegetation1 are interspersed with larger areas apparently free from salts and covered with the ordinary vegetation of the region4 ,a view of such country is given in a plate on a previous page4 ,the alkali spots are usually somewhat depressed below the surrounding lands1 and after rains remain covered with water for some time2 the water frequently assuming a brown or blackish tint after standing4 ,when a pointed steel probe is pushed down within such an alkali spot1 it will usually be found that1 although the soil may appear quite sandy1 it is penetrated with some difficulty2 while outside of the spots1 the probe does not encounter serious resistance until it reaches the depth of two or three feet1 when it frequently becomes impossible to penetrate farther without the aid of a hammer4 ,on the margin of the spots1 the transition from utter barrenness to a luxuriant vegetation of native weeds is mostly quite sudden2 as is shown in the figure1 p4 #dbe4 ,vertical ,distribution of the ,salts in ,alkali ,land4--,the results of a comparative examination of such land before and after irrigation1#afe are shown in the annexed diagrams2 in which the kind and amount of salts is shown for every three inches of vertical depth1 down to four feet1 by curves whose extension from left to right indicate the several percentages1 while the outer curved line gives the total of salts for each of the several depths4 ,fig4 #fc represents the condition of the salts in an 8alkali spot0 as found at the end of the dry season at the ,tulare substation1 ,california4 ,the soil was sampled to the depth of two feet at intervals of three inches each4 ,it is easy to see that at this time the bulk of the salts was accumulated within the first six inches from the surface1 while lower down the soil contained so little that few culture plants would be hurt by them4 ,how ,native ,plants ,live4--,fig4 #fd represents similarly the state of things in a natural soil alongside of the alkali spot1 but in which the native vegetation of brilliant flowers develops annually without any hindrance from alkali4 ,samples were taken from this spot in ,march1 near the end of the wet1 and in ,september1 near the end of the dry season1 and each series fully analyzed4 ,there was scarcely a noticeable difference in the results obtained4 ,it is seen in the figure that down to the depth of #ae inches there was practically no alkali found 7#j4jce71 and it was within these #ae inches of soil that the native plants mostly had their roots and developed their annual growth4 ,but from that level downward the alkali rapidly increased1 and reached a maximum 7#j4ebi71 at about #cc inches2 decreasing rapidly thence until1 at the end of the fourth foot in depth1 there was not more alkali than within the first foot from the surface4 ,in other words1 the bulk of the salts had accumulated at the greatest depth to which the annual rainfall 7#g inches7 ever reaches1 forming there a sheet of tough1 intractable clay-hardpan4 ,the shallow-rooted native plants germinated their seeds freely on the alkali-free surface2 their roots kept above the strongly-charged subsoil1 and through them and the stems and foliage all the soil moisture was evaporated by the time the plants died4 ,thus no alkali was brought up from below by evaporation4 ,the seeds shed would remain uninjured1 and would again germinate the coming season4 #afe ,hilgard and ,loughridge1 ,bulletin ,no4 #abh1 ,california ,experiment ,station2 ,report ,california ,experiment ,station1 #ahid-ie1 p4 #cg2 ,bulletin ,no4 #cj1 ,office of ,experiment ,stations2 ,wollny's ,forsch4 ,geb4 ,agr4 ,phys41 #ahif4 ,illustration3 ,,fig #fc4--;,diagram showing amounts and composition of alkali salts at various depths in alkali soil1 on which barley would not grow4 ,taken ,september1 #ahid4 ,tulare ,experiment ,substation1 ,california4 ,illustration3 ,,fig4 #fd4--;,diagram showing amounts and composition of alkali salts at various depths in black alkali land1 covered with native vegetation4 ,taken ,march1 #ahie4 ,tulare ,experiment ,substation1 ,california4 ,it is thus that the luxuriant vegetation of the ,san ,joaquin plains1 dotted with occasional alkali spots1 is maintained2 the spots themselves being almost always depressions in which the rain water may gather1 and where1 in consequence of the increased evaporation1 the noxious salts have risen to the surface and render impossible all but the most resistant saline growth2 particularly when1 in consequence of maceration and fermentation in the soil1 the formation of carbonate of soda has caused the surface to sink and become almost water-tight4 ,upward ,translocation from ,irrigation4--,fig4 #fe shows the corresponding profile of the same soil after several years' irrigation4 ,the upward movement of the salts is clearly seen by comparison with the previous figure2 and the surface soil has become so charged with salts that the seeds of culture plants refuse to germinate4 ,ten feet from this bare alkali ground1 on which barley had refused to grow1 a crop of barley four feet high was harvested the same year1 without irrigation4 ,investigation proved that here the condition of the soil was intermediate between the two preceding diagrams4 ,the irrigation water had dissolved the alkali of the subsoil1 and the more abundant evaporation had brought it nearer the surface2 but the shading by the barley crop and the evaporation of the moisture through its roots and leaves had prevented the salts from reaching the surface in such amounts as to injure the crop1 although the tendency to rise was clearly shown4 ,by the use of gypsum1 moreover1 the injuriousness of the alkali had been somewhat diminished4 ,the same season1 grain crops were almost a failure on alkali-free land in the same region2 and in connection with this result it should be noted as a general fact that alkali lands always retain a certain amount of moisture perceptible to the hand during the dry season1 and that this moisture can be utilized by crops2 so that at times when crops fail on non-alkaline land1 good ones are obtained where a slight taint of alkali exists in the soil4 ,actual determinations showed that while a sample of alkali soil containing 4#ed of salts absorbed #ab4c of moisture from moist air1 the same soil when leached absorbed only #b4e--;a figure corresponding to that of sandy upland loams4 ,illustration3 ,,fig4 #fe4--;,diagram showing amounts and composition of alkali salts at various depths in bare alkali land1 where barley would not grow2 irrigated4 ,taken ,september1 #ahid4 ,tulare ,experiment ,substation1 ,california4 ,illustration3 ,,fig4 #ff4--;,distribution of ,alkali ,salts in ,sandy ,lands4 ,alkali in ,sandy ,lands4--,in very sandy lands1 and particularly when the alkali is 8white0 only1 the tendency to accumulation near the surface is much less1 even under irrigation4 ,in the natural condition the salts are in such cases often found quite evenly distributed through soil columns of four feet1 and even more4 ,this is an additional cause of the lesser injuriousness of 8white alkali40 ,an illustration of the distribution of the salts in very sandy lands1 from the ,tulare substation1 is given in ,fig4 #ff4 ,here we see that the maximum is not at1 but some distance below the surface1 the entire saline mass is lower down than in the more clayey loam of the same locality1 and is more widely distributed in depth4 ,distribution of ,alkali ,salts in ,heavy ,lands4--,the mode of distribution of alkali salts in the heavier1 close-grained soil of the ,chino experimental tract in southern ,california1 is illustrated in ,fig4 #fg4 ,this land is permanently moist1 from a water-table ranging from five to seven feet below the surface in ordinary years4 ,there is therefore no opportunity for the formation of 8alkali hardpan0 as in the case of the ,tulare soil2 the salts always remain rather near the surface1 viz4 within twelve to fifteen inches4 ,but being in much smaller average amounts than at ,tulare 7an average of about #ecjj lbs4 per acre71 quite a copious natural vegetation of grasses1 sunflowers1 and 8yerba mansa0 covered the whole surface1 save in a few low spots4 ,a similar mode of distribution of the salts is found in the still more clayey 8black adobe0 lands of the ,great ,valley of ,california4 ,the scanty rains cannot penetrate these soils to any great depth1 so that evaporation will soon bring the salts carried by them back to within a short distance of the surface4 ,their accumulation there is frequently indicated by the entire absence of any but the most resistant alkali weeds1 even though the total of salts in the land may not be very great4 ,salton ,basin4--,a peculiar state of things is illustrated in the ,salton ,basin1 which represents what was at one time the head of the ,gulf of ,california1 and at the lowest point of which1 #bfh feet below sea level1 there now lies a large deposit of rock salt4 ,it has been cut off from the present ,gulf by the delta deposits of the ,colorado river1 which now1 however1 overflows into the ,basin at times of extreme high water4 ,although appearing level to the eye1 the general slope of the country is to the lowest point of the former sea-bottom4 ,the region1 now in progress of settlement by means of irrigation water brought from the river near ,yuma1 was investigated with respect to its alkali conditions in #aijj 7,bulletin ,no4 #adj1 ,calif4 ,agric4 ,expt4 ,sta474 ,the annexed diagram #fh shows the distribution of the salts to a depth of #ba feet4 ,it will be noted that here also the alkali content becomes insignificant at #d feet depth1 but increases again to a second maximum at about #ae feet1 below which there is a second decrease2 below this1 at #bj feet1 there is a final very heavy increase1 not only of the total salts but especially of common salt1 which evidently represents the drainage toward the salt deposit4 ,above this level there is a very remarkable predominance of ,glauber's salt 7sodium sulfate71 also observable elsewhere1 e4 g4 near ,white ,plains1 ,nev41 whose name is derived from the copious surface accumulation of the sulfate4 ,it seems as though this must have been formed in some way from the common salt4 ,illustration3 ,,fig4 #fg4--;,amounts and composition of alkali salts at various depths and points in the ten-acre tract at the southern ,california ,experiment ,station2 taken last week in ,april1 #ahie4 ,illustration3 ,,fig4 #fh4--;,graphic illustration of distribution of salts in ,salton ,river section1 ,california4 ,horizontal ,distribution of ,alkali ,salts in ,arid ,lands4--,the constant occurrence of 8alkali spots0 in arid lands shows at once the great inequality of horizontal distribution of alkali impregnation4 ,this is as prominent in level lands as on slopes1 and in extremely arid regions it is mostly not possible to recognize even very considerable differences without close examination4 ,thus in lands appearing exactly alike on the surface1 on the edge of the ,salton basin in ,california1 on the same forty acre #a4d 7#ef1jjj pounds per acre7 was found in the surface four feet at one point1 and a hundred yards away1 #ab4e 7#ejj1jjj pounds74 ,the mapping of alkali lands is therefore somewhat precarious unless carried into great detail4 ,moreover1 it has been found that the location of the salts changes from year to year1 especially in irrigated land1 as might be expected4 ,those cultivating alkali lands have therefore to exercise constant watchfulness1 unless the salts have been definitively eliminated by underdrainage over a considerable area2 as merely local operations may be rendered ineffectual by the migration of the salts from neighboring tracts not reclaimed4 ,alkali in ,hill ,lands4--,as a rule1 hill lands themselves are remarkably free from alkali1 even in the arid regions2 except when water is gathered in depressions1 where strongly saline waters may be found in ,washington1 ,montana and elsewhere4 ,but on level plateau lands1 where drainage is slow or imperfect1 alkali appears as freely as it does in the same regions in the stream bottoms4 ,in the latter the leachings and seepage of the uplands naturally causes a concentration of the salts1 and thus we find alkali salts incrusting the surface in the valleys of the streams1 as e4 g41 that of the ,yellowstone1 ,musselshell1 ,judith1 ,yakima and others in the north1 and of ,green river1 ,platte1 ,pecos1 and ,rio ,grande farther south2 as well as in numerous valleys of central and southern ,california4 ,usar ,lands of ,india4--,these lands have been investigated first by the 8,reh ,commission0 appointed to investigate the causes of the deterioration of lands in the ,aligarh district 7south of ,delhi1 between the ,ganges and ,jumna rivers71 in #ahgf4 ,the occasion of this appointment was the appearance of 8reh0 7alkali salts7 in a region which had previously been free from them4#aff ,subsequently1 a more elaborate investigation of the subject was made by ,dr4 ,j4 ,w4 ,leather1 ,agricultural ,chemist to the ,government of ,india4#afg ,from these documents it appears that 8usar lands0 exist largely not only in the ,northwestern ,provinces and ,oudh1 but also in the ,panjab1 especially on the lands bordering the ,chenab river2 likewise to a slight extent in the ,bombay presidency4 ,leather's investigation shows that not all the lands designated by the natives as usar contain soluble salts in injurious amounts1 some being simply lands having very hard1 clayey soils difficult to till with the imperfect methods employed4 ,yet the general phenomena of the true 8reh0 lands are practically identical with those of the ,american alkali lands1 including also the calcareous hardpan1 there called kankar4 ,owing probably to the long cultivation of the ,indian lands 7mostly under irrigation71 the salts are there at their maximum in the first foot1 decreasing as depth increases4 ,it is noteworthy also that in the majority of cases the predominant salt is carbonate of soda or black alkali1 which there as in ,california renders the lands impervious to water until treated with gypsum4 ,this fact accounts for the popular use of the same name for non-saline impervious clay soils1 and the alkali or reh lands proper4 ,we have an entirely analogous case in the 8,szek0 lands of the ,hungarian plain1 some of which are simply poor refractory soils containing a trace of soluble salts2 while lower down in the valley of the ,theiss we find genuine alkali lands1 both black and white1 which have long furnished carbonate of soda for local use and commerce4 ,in this case1 however1 the alkali salts seen to come largely1 in some cases wholly1 from underlying saline clays whose salts in coming to the surface suffer precisely the same transformations experienced in ,california and ,india1 in presence of calcic carbonate 7see below1 p4 #dej ff74 #aff ,an abstract of the report of this commission is given in the ,report of the ,california ,experiment ,station for #ahij4 #afg ,see ,agricultural ,ledger1 #ahig1 ,no4 #ac2 ibid4 #aija1 ,no4 #ac4 ,the accounts given by v4 ,middendorff of the nature and occurrence of alkali lands in ,turkestan 7,ferghana7 agree entirely with those given above for ,california and ,india2 as do also the investigations made by other ,russian observers on the saline lands of the steppes of ,european ,russia4 ,,composition ,,and ,,quantity ,,of ,,alkali ,,salts4 ,black and ,white ,alkali4--,broadly speaking1 the world over alkali salts consist mainly of three chief ingredients1 already mentioned1 namely1 common salt1 ,glauber's salt 7sulfate of soda71 and salsoda or carbonate#afh of soda4 ,the latter causes what is popularly known as 8black alkali10 from the black spots of puddles seen on the surface of lands tainted with it1 owing to the dissolution of the soil humus2#afi while the other salts1 often together with ,epsom salt and bittern 7,magnesium chlorid71 constitute 8white alkali10 which is known to be very much milder in its effect on plants than the black4 ,in most cases all three are present1 and all may be considered as practically valueless1 or noxious1 to plant growth4 #afh ,in this designation are included1 in this volume1 both the normal 7mono-7 carbonate and the two other compounds1 the bi- or hydrocarbonate and the intermediate 7so-called sesqui-7 compound or trona2 all of which are commonly present simultaneously1 but in utterly indefinite relative proportions1 varying from day to day and from inch to inch of depth1 inasmuch as their continued existence depends upon the greater or less formation of carbonic acid in the soil1 and the access of air4 ,hence their separate quantitative determination at any one time is of little practical interest4 ,all naturally occurring carbonate of soda contains1 and sometimes consists of1 these 8super-carbonates10 according to the greater or less exposure to air and solar heat4 ,they are much milder in their action on plants than the monocarbonate1 which unfortunately1 in the nature of the case1 always predominates near the surface1 and thus injures the root-crown4 #afi ,a wholly different kind of 8black alkali0 exists in some regions1 especially in the delta lands of the ,colorado of the ,west and in the ,pecos and ,rio ,grande country in ,new ,mexico4 ,in these cases the dark tint is due1 not to a humic solution1 but simply to moisture1 which is tenaciously retained by the chlorids of calcium and magnesium impregnating the land1 thus contrasting strongly with the gray tint of the general dry soil4 ,,europe4 ,,asia4 ---------------------------------------- - ,,hungarian ,,aralo-,,caspian ,,aden4 ,,plain4 ,,plain4 8,,hurka0 8,,szekso40 ,,saline ,,crusts48,,kara40 ---------------- ,debreczin,kalocsa ---------------------------------------- ----------------------- ,potassium ,sulfate 7,k,,so7 ,sodium ,sulfate 7,na,,so7 4#b #a4f #aj4d #ah4b #ae4e ,sodium ,carbonate 7,na,,co7 #dh4a #ib4e #ad4g #ab4a #fi4j #fg4b ,sodium ,chlorid 7,na,cl7 #ea4g #d4d #gd4f #fi4g #ae4e #cb4h ,sodium ,phosphate 7,na,,po7 #a4e ,calcium ,chlorid ,magnesium ,chlorid 7,mg,cl7 -------------------------------------- #ajj4j #ajj4jajj4jajj4jajj4j #ajj4j ---------------------------------------- ----------------------- ,,asia4 -------------------------------------- ,,india 8,,reh40 -------------------------------------- ,gursikar1,jellalabad1,bayamati ,aligarh1 ,panjab1 7,regur71 #f feet4 #a4e feet4 ,deccan1 #b feet4 ---------------------------------------- -------------------- ,potassium ,sulfate 7,k,,so7 #aa4a ,sodium ,sulfate 7,na,,so7 #g4j #ae4e #eh4e #b4c ,sodium ,carbonate 7,na,,co7 #gi4j #ef4i #bb4i ,sodium ,chlorid 7,na,cl7 #b4i #bg4f #ah4f #ig4g ,sodium ,phosphate 7,na,,po7 ,calcium ,chlorid ,magnesium ,chlorid 7,mg,cl7 ----------------------------------- #ajj4j #ajj4j #ajj4j #ajj4j ---------------------------------------- -------------------- ,,africa4 --------------------------------------- ,,egypt4 ------------------------- ,trona1 ,alkali ,fezzan 7,commercial47 ,l4 ,abukir4 ,trona1 7,commercial47 ---------------------------------------- ---------------------- ,potassium ,sulfate 7,k,,so7 #f4di ,sodium ,sulfate 7,na,,so7 #bc4f #ch4c 4#hb #j4f ,sodium ,carbonate 7,na,,co7 #bh4b #dg4g #a4ac #ih4g ,sodium ,chlorid 7,na,cl7 #dh4b #ad4j #hi4gd 4#g ,sodium ,phosphate 7,na,,po7 ,calcium ,chlorid #a4hb ,magnesium ,chlorid 7,mg,cl7 ------------------------------------- #ajj4j #ajj4j #ajj4jj #ajj4j ---------------------------------------- ---------------------- ,,california4 ------------------------------------- ,tulare ,county4 ,merced,overhiser--------------- ,kern ,falls4 ,san ,visalia ,expt4 ,island ,joaquin ,station4 ,co4 ,tulare4 ---------------------------------------- ----------------------- ,potassium ,chlorid1 ,k,cl ,potassium ,sulfate1 ,k,,so #bj4bc #c4ie #aj4ac ,potassium ,carbonate4 ,k,,co ,sodium ,sulfate1 ,na,,so #d4fg #ac4jj #be4bh #hh4db ,sodium ,nitrate1 ,na,n,o #ab4ih #ai4gh ,sodium ,carbonate1 ,na,,co #ge4ie #eb4bb #fe4gb #cb4eh #j4db ,sodium ,chlorid1 7,na,cl7 #a4df #cc4jj #c4ih #ad4ge #j4ea ,sodium ,phosphate1 ,h,na,,po #d4id #a4gh #h4db #b4be ,magnesium ,sulfate1 ,mg,s,o #a4fe #j4eb ,calcium ,chlorid ,magnesium ,chlorid ,ammonium ,carbonate1 ,,nh,,co #a4da ---------------------------------------- ----------------------- #ajj4jj #ajj4jj #ajj4jj #ajj4jjajj4jj ---------------------------------------- ----------------------- ,,california4 ------------------------------------- ,mojave ,hunts1 ,westminster ,imperial ,plateau near near ,san ,santa ,ana4 ,bernardino ---------------------------------------- ------------------------ ,potassium ,chlorid1 ,k,cl #a4ae ,potassium ,sulfate1 ,k,,so #j4ib #e4ca #bj4fb ,potassium ,carbonate4 ,k,,co #f4ei ,sodium ,sulfate1 ,na,,so #dc4cd #ff4jh ,sodium ,nitrate1 ,na,n,o #h4ba ,sodium ,carbonate1 ,na,,co #ae4ch #ae4he #fb4bb 4#eh ,sodium ,chlorid1 7,na,cl7 #ci4cd #aa4dg #aj4eg #ca4hb ,sodium ,phosphate1 ,h,na,,po #a4jb ,magnesium ,sulfate1 ,mg,s,o #j4ei ,calcium ,chlorid #eh4db ,magnesium ,chlorid #b4ha ,ammonium ,carbonate1 ,,nh,,co ---------------------------------------- ------------------------ #ajj4jj #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- ------------------------ ,,washington4 ---------------------------------- ,yakima ,spokane ,co4 ,kittitas ,whitman ,co41 on ,valley4 ,co41 ,cottonwood ,atahnam ,lake ,springs4 ,creek4 ,creek4 ---------------------------------------- --------------------- ,potassium ,chlorid1 ,k,cl #c4ij #j4af #d4ec #f4bg ,potassium ,sulfate1 ,k,,so #ah4dd #ae4ag #ae4ij ,potassium ,carbonate4 ,k,,co ,sodium ,sulfate1 ,na,,so ,sodium ,nitrate1 ,na,n,o #ge4fa #hj4cf #gg4aj #hg4ad ,sodium ,carbonate1 ,na,,co #j4eb #a4gf #a4cd #d4jc ,sodium ,chlorid1 7,na,cl7 #a4ec #b4ee #a4ac #b4ef ,sodium ,phosphate1 ,h,na,,po ,magnesium ,sulfate1 ,mg,s,o ,calcium ,chlorid ,magnesium ,chlorid ,ammonium ,carbonate1 ,,nh,,co ---------------------------------------- --------------------- #ajj4jj #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- --------------------- ,,montana4 ---------------------------------------- --------------------------- ,,upper ,,missouri ,,valley4 --------------------------------------- ,upper ,prickly ,ford ,fort ,robert's ,missouri ,pear on ,benton4 ,creek1 ,valley ,plain4 ,sun ,mussel- near ,helena4,river4 shell ,centerville ,valley4 ---------------------------------------- ----------------------- ,potassium ,sulfate1 ,k,,so #b4cg #c4jg #a4gg #h4ei #c4jg ,sodium ,sulfate1 ,na,,so #ef4ed #dc4ch #hc4ce #dg4aj #gf4gi ,sodium ,nitrate1 ,na,n,o #i4ci ,sodium ,carbonate1 ,na,,co 4#ga #ac4ii ,sodium ,chlorid1 ,na,cl #bg4dg #ad4fj #j4ia 4#ah #f4ae ,magnesium ,sulfate1 ,mg,s,o #d4bc #ch4id #ac4ig #dc4db ,potassium ,chlorid1 ,k,cl --------------------------------------- #ajj4jj #ajj4jjajj4jj #ajj4jj #ajj4jj ---------------------------------------- ----------------------- ,,nevada4 ----------------------------- ,,near ,,reno4 ,churchill ,county4 ---------------------------------------- ------------ ,potassium ,sulfate1 ,k,,so ,sodium ,sulfate1 ,na,,so #eb4ae #hj4cj #j4ee ,sodium ,nitrate1 ,na,n,o ,sodium ,carbonate1 ,na,,co #de4cg #ae4bd #if4gh ,sodium ,chlorid1 ,na,cl #b4dh #d4df #b4fg ,magnesium ,sulfate1 ,mg,s,o ,potassium ,chlorid1 ,k,cl ---------------------------- #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- ----------- ,,wyoming4 ---------------------------------------- ,,sweet ,,water ,,laramie ,,farm4 ,,valley4 -------------------------------------- ,independence1 ,saint ,alkali4 ,waste ,rock ,mary's ,irrigation ,lake4 ,station4 ,water4 ---------------------------------------- ---------------------- ,potassium ,sulfate1 ,k,,so ,sodium ,sulfate1 ,na,,so #gc4ag #hh4ic #ei4bi #da4ai ,sodium ,nitrate1 ,na,n,o ,sodium ,carbonate1 ,na,,co #bb4ih ,sodium ,chlorid1 ,na,cl #c4he #aa4fc #ag4ja #b4ah ,magnesium ,sulfate1 ,mg,s,o #bc4gj #dc4hb ,potassium ,chlorid1 ,k,cl #ab4ha -------------------------------------- #ajj4jj #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- ---------------------- ,,colorado4 ------------------------------------ ,near ,grand ,rocky ,rocky ,denver4 ,junction4 ,ford4 ,ford4 ---------------------------------------- -------------------- ,potassium ,sulfate1 ,k,,so #j4aj #ac4gd ,sodium ,sulfate1 ,na,,so #ic4dj #ef4je #fb4ed #ag4cf ,sodium ,carbonate1 ,na,,co #ah4ig #b4jh #e4ec ,sodium ,chlorid1 ,na,cl #f4fj #bd4ih #c4hf #aa4ec ,magnesium ,sulfate1 ,mg,s,o #ca4db #dd4dc ,magnesium ,chlorid1 ,mg,cl #e4gf ,magnesium ,phosphate #a4fe ------------------------------------ #ajj4jj #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- -------------------- ,,new ,,mexico4 ---------------------------------------- --- ,,pecos ,,valley4 ---------------------------------------- -- ,,roswell ,,region4 ,,carlsbad ,,region4 --------------------------------------- ,bremond,michelet,roswell,carlsbad,delaw are ,river ---------------------------------------- ----------------------- ,potassium ,sulfate1 ,k,,so ,sodium ,sulfate1 ,na,,so #ed4fa #b4fb #fg4df #ce4af #cg4aa ,sodium ,carbonate1 ,na,,co ,sodium ,chlorid1 ,na,cl #ea4fj #fe4af #aj4jj #bf4hh #cd4ca ,magnesium ,sulfate1 ,mg,s,o #ac4gi #cb4bb #bb4ed #ch4jf #bh4eh ,magnesium ,chlorid1 ,mg,cl ,magnesium ,phosphate --------------------------------------- #ajj4jj #ajj4jj #ajj4jj #ajj4jj #ajj4jj ---------------------------------------- ----------------------- ,nutritive ,salts in ,alkali4--,with them1 however1 there are almost always associated1 in varying amounts1 sulfate of potash1 phosphate of soda1 and nitrate of soda1 representing the three elements--potassium1 phosphorus1 and nitrogen--upon the presence of which in the soil in available form1 the welfare of our crops so essentially depends1 and which we aim to supply in fertilizers4 ,the potash salt is usually present to the extent of from #e to #bj per cent of the total salts2 phosphate1 from a fraction of one to as much as #d percent2 the nitrate from a fraction of one to as much as #bj percent4 ,in black alkali the nitrate is usually low1 the phosphate high2 in the white1 the reverse is true4 ,both relations are readily intelligible from a chemical and bacteriological point of view4 ,estimation of ,total ,alkali in ,land4--,the investigations detailed above having shown that in ,california at least1 outside of the axes of valleys no practically important amount of alkali salts is usually found at a depth exceeding four feet1 it became possible to determine approximately the amounts of salts that would have to be dealt with when irrigation and evaporation should bring the entire amount to or near the surface2 a necessary prerequisite to the determination of possible cultures4 ,while1 as already shown1 the salts occur lower down in very sandy lands1 yet the diagram on p4 #dce shows that even then1 an estimate on this basis would not be very wide of the truth4 ,it is at least probable that the same is measurably true of level alkali lands elsewhere1 when not underlaid by geological deposits impregnated with salts4 ,the total amount of these salts ordinarily found in alkali lands 7i4 e4 in such as in the dry season show saline efflorescences on the surface7 is from about one tenth of one per cent to as much as three per cent of the weight of the soil1 taken to the depth of four feet4 ,the percentage of salts having been determined in samples representing a tract1 it becomes easy to calculate1 approximately1 the total amounts of each salt present per acre1 on the basis of the weight of the soil per acre foot4 ,for the soils of the arid region1 such weight will usually range from three million five hundred thousand to four million pounds per acre-foot2 the latter being the most usual figure1 of which it may be conveniently remembered1 that forty thousand pounds represent #a per cent4 ,we are thus enabled to estimate e4 g4 the amount of gypsum required to neutralize the carbonate of soda in the salts1 or the amounts of valuable nutritive ingredients--potash1 phosphoric acid and nitrates--present in the land in the water-soluble form4 ,as has been shown in the preceding discussion1 the analysis at the surface foot alone1 which has frequently been alone made1 gives no definite clew whatever to the total amounts of salts to be controlled4 ,a full estimate is of special importance in enabling us to forecast what culture plants are likely to succeed on a given tract1 by reference to the table of 8tolerances0 given below 7chapter #bc1 page #dfg74 ,composition of ,alkali ,soils as a ,whole4--,as may be imagined1 the presence of the alkali salts finds expression in the analytical statement of their composition1 although not to the extent usually anticipated from their superficial aspect4 ,the table annexed gives the composition of fourteen alkali soils1 taken to the depth of one foot1 at times when there was no visible accumulation of salts on the surface4 ,the averages of the several ingredients determined are given in the fifteenth column1 and a comparison of its figures with those of the general table on page #cgg of chapter #bj will show some marked characteristics4 ,we find the average potash-content to be but little less than twice as great as in the general average for the state of ,california2 in the case of lime the ratio is nearly as one to three1 in the case of magnesia nearly one to two2 in that of phosphoric acid1 one to two and a half1 of which in the presence of carbonate of soda an unusually large proportion is in a readily soluble1 often in the water-soluble1 condition 7see preceding table74 ,the usual proportion of soda1 of one-fourth to one-half of the amount of potash1 is changed to one-half or three-fourths2 in the case of the strongest alkali lands soda may equal or even exceed the potash content4 ,as the latter1 however1 is invariably high to very high1 it does not happen as frequently as might be supposed that the soda content exceeds that of potash as shown by the usual method of soil-extraction with water4 ,that the potash percentage should always be high in alkali lands1 is hardly surprising when it is considered that the continued presence of the salts resulting from rock decomposition affords opportunity for the full exercise of the preference with which potash is known to be retained in soils by the formation of complex zeolitic silicates4 ,in most cases the potash-percentage exceeds 4#ge1 and rises as high as #b4j2 as is shown in the table4 ,,composition ,,of ,,alkali ,,soils ,,as ,a ,,whole4 7,a7 ,white ,ash1 ,fresno4 7,b7 ,wire ,grass1 ,visalia4 7,c7 ,plains1 ,cross ,creek1 ,tulare 7,d7 ,salt ,grass1 ,b4 ,v4 ,slough4 ,,collection ,,number4 7,a7 7,b7 7,c7 7,d7 --#gjd-- --#ehe-- --#egc-- --#gjj-- ---------------------------------------- --------------------- ,coarse ,materials #j4ee mm #ad4bi #a4ej ,fine ,earth #he4ga #ih4ej ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ---------------------- ,insoluble matter #he4hg #ff4dg #ff4jh #hg4jf #hh4eh #ga4db #fi4df #hi4jd ,soluble silica #b4ga #d4ie #c4ch #a4ih ---------------------------------------- --------------------- ,potash 7,k,o7 4#cd #a4bb #a4hb 4#di ,soda 7,na,o7 4#be 4#fh 4#dd 4#ce ,lime 7,ca,o7 #a4af #c4jd #d4ca #a4bj ,magnesia 7,mg,o7 4#ej 4#ji #a4ei #a4jg ,bro4 ox4 of ,manganese 7,mn,o7 4#jc 4#jc 4#jh 4#jc ,peroxid of ,iron 7,fe,o7 #c4bh #e4hb #f4jd #e4hb ,alumina 7,al,o7 #c4bb #g4ad #h4fi 4#ag ,phosphoric acid 7,p,o7 4#aj 4#bd 4#gd 4#jh ,sulfuric acid 7,,so7 4#ab 4#ff 4#bf 4#ac ,carbonic acid 7,,co7 #b4ee #b4ec ,water and organic matter #a4gi #g4ji #d4ae #a4ac -------------------------------- ,total #ii4cg #ii4ig #ii4ea #ii4ea -------------------------------- ,chlorin1 per cent4 ,humus 4#fj #a4jj #a4jj 4#ag 8 ,ash 4#ce 4#hd 4#gd 4#bj -------------------------------- 8 ,nitrogen1 per cent4 in ,humus #ah4ff #ad4aj -------------------------------- 8 8 1 per cent4 in soil 4#aa 4#ae -------------------------------- ,hygroscopic ,moisture #b4bb #h4ec #h4gd #b4af absorbed at ,c #ad #ae ---------------------------------------- --------------------- ,tulare ,lake ,alluvium1 ,tulare ,county4 ,,collection ,,number4 --#hia-- --#hic-- --#gg-- ---------------------------------------- ----------------- ,coarse ,materials #j4ee mm #d4aj ,fine ,earth all all #ie4ij ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ----------------- ,insoluble matter #ed4ga #ef4ib #fg4cd #fd4ee #fg4ae ,soluble silica #i4hd #aj4ac ---------------------------------------- ----------------- ,potash 7,k,o7 #b4jb #a4fe #a4je ,soda 7,na,o7 #b4gc 4#ed 4#hd ,lime 7,ca,o7 #b4df #b4if #f4ea ,magnesia 7,mg,o7 #b4ic #c4ab #c4fi ,bro4 ox4 of ,manganese 7,mn,o7 4#jc 4#jd 4#jd ,peroxid of ,iron 7,fe,o7 #g4df #f4gc #e4je ,alumina 7,al,o7 #aa4ej #aj4ce #g4ig ,phosphoric acid 7,p,o7 4#aa 4#af 4#cb ,sulfuric acid 7,,so7 4#ja 4#ja 4#jh ,carbonic acid 7,,co7 #a4ha 4#ic #d4db ,water and organic matter #d4cd #e4gg #c4ga ---------------------------- ,total #ii4ie #ii4ib #aja4bi ---------------------------- ,chlorin1 per cent4 ,humus 4#hh 4#dg 8 ,ash #a4jc #b4ah ---------------------------- 8 ,nitrogen1 per cent4 in ,humus #i4cg ---------------------------- 8 8 1 per cent4 in soil 4#je ---------------------------- ,hygroscopic ,moisture #aj4ej #h4f absorbed at ,c #aj #aj ---------------------------------------- ----------------- ,,composition ,,of ,,alkali ,,soils ,,as ,a ,,whole4 ,tulare ,ten-acre tract4,carisa ,plain ,,collection ,,number ,substation,chino1 ,s4,b4 ,co4 ,s4,l4 ,obispo --#aaei-- --#abhd-- --#adbc-- ---------------------------------------- ------------------------- ,coarse ,materials #j4eemm4 #a4if #a4jj #i4jj ,fine ,earth4 #ih4jd #ii4jj #ia4jj ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ------------------------- ,insoluble matter #gb4ih #fb4fb #eg4cc #gc4eh #gj4ib #fi4dh ,soluble silica #f4fj #ah4cj #ab4ae ---------------------------------------- ------------------------- ,potash 7,k,o7 #a4bj 4#ie #a4bc ,soda 7,na,o7 4#eb 4#ej 4#gg ,lime 7,ca,o7 #a4hf #e4jg #d4df ,magnesia 7,mg,o7 #a4ha 4#hd #c4ab ,br4 ox4 of ,manganese 7,mn,o7 4#jh 4#jf 4#ja ,peroxid of ,iron 7,fe,o7 #f4hf #f4dc #g4fe ,alumina 7,al,o7 #e4ff #d4hh #f4af ,phosphoric acid 7,p,o7 4#aj 4#ba 4#dc ,sulfuric acid 7,,so7 4#jc 4#jf 4#jf ,carbonic acid 7,,co7 #c4gf ,water and organic matter #b4ed #a4jb #b4fc ,total #ajj4bd #ii4gj #ii4ii ------------------------------------- ,chlorin1 per cent 4#ab ,humus1 per cent 4#cg #a4ii #a4ci 8 ,ash1 per cent 4#cb #a4ac 4#ie ------------------------------------- 8 ,nitrogen1 per cent4 in ,humus #af4ge #aj4bj #ad4cf 8 8 1 per cent4 in soil 4#jf 4#bj 4#jf ------------------------------------- ,hygroscopic ,moisture #e4ha #h4df absorbed at ,c #ae #ae ---------------------------------------- ------------------------ ,perris ,valley1 ,sand1 ,coachella1 ,,collection ,,number ,jacinto river1 ,jacinto ,riverside ,plain1 ,riverside ,co4 ,co4 --#ageh-- --#agfj-- --#bdga-- ---------------------------------------- ------------------------- ,coarse ,materials #j4eemm4 #g4ej #c4ej ,fine ,earth4 #ib4ej #if4ej all ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- ------------------------- ,insoluble matter #da4ei #ce4bj #eh4ie #fc4ac #eh4ie #gg4ed ,soluble silica #ba4ed #bc4ge #aa4cg ---------------------------------------- ------------------------- ,potash 7,k,o7 #a4cg #a4af #a4bf ,soda 7,na,o7 #a4ig 4#if 4#cg ,lime 7,ca,o7 #d4bc #h4jj #b4ga ,magnesia 7,mg,o7 #c4hj #e4fi #b4bj ,br4 ox4 of ,manganese 7,mn,o7 4#jc 4#jd 4#je ,peroxid of ,iron 7,fe,o7 #i4fe #g4cc #f4dc ,alumina 7,al,o7 #g4bf #f4bi #e4ec ,phosphoric acid 7,p,o7 4#bc 4#bh 4#ba ,sulfuric acid 7,,so7 4#cd 4#ba 4#jh ,carbonic acid 7,,co7 #d4ai #f4di #a4je ,water and organic matter #b4hi #d4ga #b4ee ,total #ii4ha #ii4hd #ii4ih ------------------------------------- ,chlorin1 per cent ,trace4 ,humus1 per cent 4#fj 4#ia 4#df 8 ,ash1 per cent 4#ib #a4ge 4#db ------------------------------------- 8 ,nitrogen1 per cent4 in ,humus #f4ff #g4gj 8 8 1 per cent4 in soil 4#jd 4#jg ------------------------------------- ,hygroscopic ,moisture #i4dc #h4he #b4fd absorbed at ,c #ae #ae #ae ---------------------------------------- ------------------------- ,silt1 ,imperial1,average of ,,collection ,,number ,s4 ,diego ,co4 soils4 --#bcbe-- ---------------------------------------- -------------- ,coarse ,materials #j4eemm4 ,fine ,earth4 all ,,chemical ,,analysis ,,of ,,fine ,,earth4 ---------------------------------------- -------------- ,insoluble matter #fb4fg #fc4jh #gc4fj #gb4ai ,soluble silica #aj4ic #i4aa ---------------------------------------- -------------- ,potash 7,k,o7 4#gd #a4ag ,soda 7,na,o7 4#bi 4#gh ,lime 7,ca,o7 #c4ge #c4ga ,magnesia 7,mg,o7 #a4fh #b4bi ,br4 ox4 of ,manganese 7,mn,o7 4#ja 4#jd ,peroxid of ,iron 7,fe,o7 #c4ga #f4cj ,alumina 7,al,o7 #d4bf #f4fe ,phosphoric acid 7,p,o7 4#bb 4#bj ,sulfuric acid 7,,so7 4#cf 4#ag ,carbonic acid 7,,co7 #b4cb #b4ad ,water and organic matter #h4ic #d4ai ,total #ii4hg -------------------------- ,chlorin1 per cent ,humus1 per cent 4#fe 4#ge 8 ,ash1 per cent 4#fi 4#hb -------------------------- 8 ,nitrogen1 per cent4 in ,humus #aj4ij 8 8 1 per cent4 in soil 4#jg -------------------------- ,hygroscopic ,moisture #b4ih #e4fc absorbed at ,c #ae #ae ---------------------------------------- -------------- ,this table exhibits also another standing characteristic of alkali soils1 which is to be anticipated from the conditions of their formation2 viz1 high lime-content1 which sometimes rises to the extent of marliness4 ,in phosphates1 also1 alkali soils are almost always high2 and an unusually large proportion is found to be readily soluble4 ,in presence of much carbonate of soda1 nitrates are usually scarce or altogether absent2 while owing to the action of the alkaline solution upon the humus1 ammonia salts1 or even free 7or carbonated and therefore readily dissociated and assimilated7 ammonia may be present1 so as to be perceptible to the senses by its odor in hot sunshine4 ,but in the case of 8white alkali10 more especially of the sulphate in moderate amounts1 nitrification is exceedingly active and nitrates may sometimes rise to as much as #bj of the soluble salts4 ,as alkali spots are usually low in the central portion and therefore more moist than around the edges1 we sometimes find ammonia salts in the middle of a spot1 while nitrates are abundant along the margin of the same4 ,these differences1 first demonstrated by an investigation made by ,colmore1#agj illustrate some of the reactions that are essentially concerned in the agricultural availability of alkali lands4 ,a summary of ,colmore's results is given in the table below4 #agj ,report of the ,california ,exp't4 ,st'n4 for #ahib-id1 p4 #ada4 ,cross ,section of an ,alkali ,spot4--,the spot examined lies outside of ,tulare1 ,california1 substation2 it being late in the season1 when the bulk of the salts is found near the surface1 the samples were taken to the depth of one foot only1 at points four feet apart1 from the center out4 ,,amount ,,and ,,composition ,,of ,,salts ,,in ,,alkali ,,spot ,,from ,,center ,,to ,,circumference4 #d ,,feet ,,apart1 #a ,,ft4 ,,depth4 #a #b #c #d #e ,mineral ,salts4 ,center ,four ,eight ,twelve ,outer of spot4 feet4 feet4 feet4 margin4 ---------------------------------------- ---------------------- ,potassium sulfate #f4gj #i4ee #aa4ib #ai4bf #ac4ie ,sodium sulfate #ai4hd #ab4he #bc4gb #bc4ig #af4if ,magnesium sulfate #c4jg 4#jg 4#ie #b4je #h4bi ,sodium chlorid #ac4hj #bc4gc #bd4ab #bd4bc #bi4fi ,sodium carbonate #ej4gb #ej4if #cg4ee #ce4di #bi4id ,sodium phosphate #e4eg #b4hh 4#hg 8 #a4jd ,sodium nitrate 4#cj 8 4#hg 8 4#ac ------ ------ ------ ------ ------ ,totals #ajj4jj #ajj4jj #ajj4jj #ajj4jj #ajj4jj ,organic matter #cj4jj #bd4hj #ai4dh #bc4cf #bj4ca ,total soluble in soil 4#gh 4#ed 4#gj 4#cg 4#cd ,mineral salts 4#ch 4#dj 4#ed 4#be 4#bc ---------------------------------------- ---------------------- ,while the table shows an obvious irregularity in some of the data at the eight-foot point1 arising doubtless from an irregularity of surface or of texture overlooked in taking the samples1 we find a very remarkable regularity of progression in the cases of potassium sulfate1 sodium chlorid1 sodium carbonate and sodium phosphate in the other four samples4 ,the maxima of the 8black alkali0 and the soluble organic matter 7humus7 coincide1 as does that of the phosphate2 the total mineral salts at the outer margin are only a little over half of what is found at the center4 ,this is natural1 as owing to the deflocculating effect of the black alkali1 the center is nearly a foot lower than the margin4 ,the lowering of the nitrate-content at the outer margin is obviously due to the luxuriant vegetation growing adjacent4 ,reactions between the ,carbonates1 ,chlorids and ,sulfates of ,alkalies and ,earths4 ,that a soluble earth-salt1 such as the sulfate or chlorid of calcium1 will react upon an alkaline carbonate solution so as to form an alkali sulfate1 and e4g4 lime carbonate1 is well known2 the neutralization of the sodic carbonate in the soil by means of gypsum1 above referred to1 is based upon this reaction4 ,it is not so well known that the latter may be reversed1 partly or wholly1 by the presence of carbonic acid in the solution of the soil4 ,although observed as early as #ahbd by ,brandes1 and again in #ahei by ,a4 ,mller1 this reaction is not mentioned in text-books and attracted no attention as a source of naturally occurring alkali carbonates which in the past have formed the basis of extensive commerce from the ,orient1 until in #ahhh1 the writer together with ,weber and later with ,jaffa1 investigated it quantitatively4#aga ,it was found that up to 4#ge grms4 per liter1 the entire amount of sodic sulfate present in solution is transformed into carbonate in presence of calcic carbonate1 by a current of carbonic dioxid2 but the amount so transformed does not continue to increase beyond about #d grams per liter4 ,a corresponding amount of calcic sulfate is formed4 ,in the case of potassic sulfate1 the transformation also occurs1 proportionally to the molecular weight4 ,this relation is shown in the subjoined diagram1 which also shows in the curves on the left1 the residual alkalinity left after evaporation and drying the residue at #ajj ,c4 #aga ,proc4 ,am4 ,soc4 ,agr4 ,sci41 #ahhh2 ibid41 #ahij2 ,rep4 ,cal4 ,expt4 ,sta41 #ahij1 p4 #ajj2 ,ber4 ,berlin1 ,chem4 ,ges41 #ahic2 ,am4 ,jour4 ,sci41 ,august #ahif4 ,illustration3 ,,fig4 #fi4--,progressive ,transformation of ,alkali ,sulfates into ,carbonates4 7,the figures along upper line represent tenths of one per cent47 ,the corresponding reaction occurs also1 of course1 between sodium chlorid and calcium carbonate1 but not to the same extent1 because unlike the difficultly soluble gypsum1 the reaction product is the very soluble calcium chlorid1 the presence of which in the solution limits the reaction much sooner than when most of the decomposition product is thrown down in the solid state4 ,the calcium chlorid not uncommonly found in some alkali regions is undoubtedly the product of the above reaction4 ,as the saline solutions in the soil are mostly quite dilute1 and calcic carbonate is always present1 it follows that whenever under the influences which favor the oxidation of organic matter in the soil1 and the activity of the plant roots1 carbonic gas is formed somewhat copiously1 alkali sulfates and chlorids present may be partially or wholly transformed into carbonates within the soil4 ,as a matter of fact1 it is found that this transformation occurs most readily in the moister portions of the soil and subsoil1 and invariably so when an alkali soil is 8swamped0 by excessive irrigation or rise of bottom water2 while the reaction is again reversed whenever free access of air reduces the carbonic dioxid below a certain point4 ,it thus becomes intelligible why in the diagrams showing the distribution of the salts 7this chapter pp4 #dca and #dcb71 we always find the sodic carbonate relatively decreasing as the surface is approached4 ,thus1 also1 is explained the fact that sodium carbonate is formed more abundantly toward the center of the root system of alkali plants1 such as the greasewood1 beneath which the soil is always more abundantly charged with 8black alkali0 than is the surrounding earth4 ,good aeration of the soil mass1 then1 is essential in maintaining the neutralization of the 8black alkali0 soils brought about by the use of gypsum 7land plaster74 ,inverse ,ratios of ,alkali ,carbonates and ,sulfates4--,according to the above considerations1 it is not surprising that we should often find an apparent inverse ratio between the alkali sulfates and carbonates in soils so closely adjacent that their salts must be presumed to be similar in composition4 ,a striking example is shown in fig4 #gj1 in which this inverse ratio becomes apparent four times in succession in one and the same soil profile4 ,while this inference is plain on the face of the diagram1 it is not quite easy to explain in detail how this alternation came about from the condition observed two months previously4 ,most probably it was caused by corresponding alternations of weather1 in which short1 warm spring showers alternated with similarly brief periods of drying north winds2 the latter causing a reversal of the formation of sodic carbonate that had been induced by the former4 ,illustration3 ,,fig4 #gj4--;,amounts and ,composition of ,alkali ,salts at various depths in partly reclaimed ,alkali ,land4 ,tulare ,experiment ,substation1 ,california4 ,exceptional ,conditions4--,while the phenomena of alkali lands as outlined above probably represent the vastly predominant conditions on level lands1 yet there are exceptions due to surface conformation1 and the local existence of sources of alkali salts outside of the soil itself4 ,such is the case where salts ooze out of strata cropping out on hillsides1 as at some points in the ,san ,joaquin ,valley in ,california1 and in parts of ,new ,mexico1 ,colorado and ,wyoming2 also where1 as in the ,hungarian plain1 saline clays underlie within reach of surface evaporation4 ,again1 it not infrequently happens that in sloping valleys or basins1 where the central 7lowest7 portion receives the salts leached out of the soils of the adjacent slopes1 we find belts of greater or less width in which the alkali impregnation may reach to the depth of ten or twelve feet1 usually within more or less definite layers of calcareous hardpan1 likewise the outcome of the leaching of the valley slopes4 ,such areas1 however1 are usually quite limited1 and are at present scarcely reclaimable without excessive expenditure2 the more as they are often underlaid by saline bottom water4 ,in these cases the predominant saline ingredient is usually common salt1 as might be expected and as is exemplified in the ,great ,salt ,lake of ,utah1 in the ,antelope and ,perris ,valleys1 and in ,salton basin in ,california2 in the ,yellowstone valley near ,billings1 ,mont4#agb in the ,aralo-,caspian desert1 and at many other points4 #agb ,farmer's ,bull4 ,no4 #hh1 ,u4 ,s4 ,dept4 ,agr41 #ahii4 ,conclusions4--,summing up the conclusions from the foregoing facts and considerations1 we find that-- 7#a7 ,the amount of soluble salts in alkali lands is usually limited2 they are not ordinarily supplied in indefinite quantities from the bottom-water below4 ,these salts have mostly been formed by weathering in the soil-layer itself4 7#b7 ,the salts move up and down within the upper four or five feet of the soil and subsoil1 following the movement of the moisture2 descending in the rainy season to the limit of the annual moistening as a maximum1 and then reascending or not1 according as surface evaporation may demand4 ,at the end of the dry season1 in untilled irrigated land1 practically the entire mass of salts may be within six or eight inches of the surface4 7#c7 ,the direct injury to vegetation#agc is caused largely within a few inches of the surface1 by the corrosion of the bark1 usually near the root crown4 ,this corrosion is strongest when carbonate of soda 7salsoda7 forms a large proportion of the salts2 the soda then also dissolves the vegetable mold and causes blackish spots in the soil1 popularly known as black alkali4 #agc ,for a general statement and discussion of the physiological effects of saline solutions on plants1 see chapter #bf4 7#d7 ,the injury caused by carbonate of soda is aggravated by its action in puddling the soil so as to cause it to lose its crumbly or flaky condition1 rendering it almost or quite untillable and impervious4 ,it also tends to form in the depths of the soil-layer a tough1 impervious hardpan1 which yields neither to plow1 pick1 nor crowbar4 ,its presence is easily ascertained by means of a pointed steel sounding-rod4 7#e7 ,while alkali lands share with other soils of the arid region the advantage of unusually high percentages of plant-food in the insoluble form1 they also contain1 alongside of the noxious salts1 considerable amounts of water-soluble plant-food4 ,when1 therefore1 the action of the noxious salts is done away with1 they should be profusely and lastingly productive2 particularly as they are always naturally somewhat moist in consequence of the attraction of moisture by the salts1 and are therefore less liable to injury from drought than the same soils when free from alkali4 ,,chapter ,,xxiii4 ,,utilization ,,and ,,reclamation ,,of ,,alkali ,,lands4 ,alkali-,resistant ,crops4--,the most obvious mode of utilizing alkali lands is to occupy them with crops not affected by the noxious salts4 ,unfortunately but few such crops of general utility have as yet been found for the stronger class of alkali lands4 ,the question is always one of degree1 which frequently cannot be decided without an actual determination of the amount and kind of salts to be dealt with1 to which the crops can then be adapted in accordance with the greater or less sensitiveness of the several plants1 as indicated in the table of tolerances given farther on4 ,but aside from this1 there are certain general measures and precautions which in any case will serve to mitigate the effect of the alkali salts4 ,foremost among these1 and applicable everywhere1 is the prevention of evaporation to the utmost extent possible4 ,counteracting ,evaporation4--,since evaporation of the soil-moisture at the surface is what brings the alkali to the level where the main injury to plants occurs1 it is obvious that evaporation should be prevented as much as possible4 ,this is the more important1 as the saving of soil-moisture1 and therefore of irrigation water1 is attainable by the same means4 ,three methods for this purpose are usually practiced1 viz41 shading1 mulching1 and the maintenance of loose tilth in the surface soil to such depth as may be required by the climatic conditions4 ,as to mulching1 it is already well recognized in the alkali regions of ,california as an effective remedy in light cases4 ,fruit trees are frequently thus protected1 particularly while young1 after which their shade alone may 7as in the case of low-trained orange trees7 suffice to prevent injury4 ,the same often happens in the case of low-trained vines1 small-fruit1 and vegetables4 ,sanding of the surface to the depth of several inches was among the first attempts in this direction2 but the necessity of cultivation1 involving the renewal of the sand each season1 renders this a costly method4 ,straw1 leaves1 and manure have been more successfully used2 but even these1 unless employed for the purpose of fertilization1 involve more expense and trouble than the simple maintenance of very loose tilth of the surface soil throughout the dry season2 a remedy which1 of course1 is equally applicable to hoed field crops1 and is in the case of some of these--e4 g41 cotton--a necessary condition of cultural success everywhere4 ,the wide prevalence of 8light0 soils in the arid regions1 from causes inherent in the climate itself1 renders this condition relatively easy of fulfilment4 ,turning-under of ,surface ,alkali4--,aside1 however1 from the mere prevention of surface evaporation1 another favorable condition is realized by this procedure1 namely the commingling of the heavily salt-charged surface-layers with the relatively non-alkaline subsoil4 ,since in the arid regions the roots of all plants retire farther from the surface because of the deadly drought and heat of summer1 it is usually possible to cultivate deeper than could safely be done with growing crops in humid climates4 ,yet even there1 the maxim of 8deep preparation and shallow cultivation0 is put into practice with advantage1 only changing the measurements of depth to correspond with the altered climatic conditions4 ,thus while in the humid ,states1 three to four inches is the accepted standard of depth for summer cultivation to preserve moisture without injury to the roots1 that depth must in the arid region frequently be doubled in order to be effective2 and will even then scarcely touch a living root in orchards and vineyards1 particularly in unmanured and unirrigated land4 ,a glance at fig4 #fc1 7chap4 #bb1 p4 #dca71 will show the great advantage of extra-deep preparation in commingling the alkali salts accumulated near the surface with the lower soil-layers1 diffusing the salts1 say through twelve instead of six inches of soil mass4 ,this will in very many cases suffice to render the growth of ordinary crops possible if1 by subsequent frequent and thorough cultivation1 surface evaporation1 and with it the re-ascent of the salts to the surface1 is prevented4 ,a striking example of the efficiency of this mode of procedure was observed at the ,tulare substation1 ,california1 where a portion of a very bad alkali spot was trenched to the depth of two feet1 throwing the surface soil to the bottom4 ,the spot thus treated produced excellent wheat crops for two years--the time it took the alkali salts to reascend to the surface4 ,it should therefore be kept in mind that whatever else is done toward reclamation1 deep preparation and thorough cultivation must be regarded as prime factors for the maintenance of production on alkali lands4 ,the ,efficacy of ,shading1 already referred to1 is strikingly illustrated in the case of some field crops which1 when once established1 will thrive on fairly strong alkali soil1 provided that a good thick 8stand0 has once been obtained4 ,this is notably true of the great forage crop of the arid region1 alfalfa or lucern4 ,its seed is extremely sensitive to 8black0 alkali1 and will decay in the ground unless protected against it by the use of gypsum in sowing4 ,but when once a full stand has been obtained1 the field may endure for many years without a sign of injury4 ,here two effects combine1 viz41 the shading1 and the evaporation through the deep roots and abundant foliage1 which alone prevents1 in a large measure1 the ascent of the moisture and salts to the surface4 ,the case is then precisely parallel to that of the natural soil 7see p4 #dcb1 chapter #bb71 except that1 as irrigation is practiced in order to stimulate production1 the sheet of alkali hardpan will be dissolved and its salts spread through the soil more evenly4 ,the result is that so soon as the alfalfa is taken off the ground and the cultivation of other crops is attempted1 an altogether unexpectedly large amount of alkali comes to the surface and greatly impedes1 if it does not altogether prevent1 the immediate planting of other crops4 ,shallow-rooted annual crops that give but little shade1 like the cereals1 while measurably impeding the rise of the salts during their growth 7see fig4 #gj1 page #deb7 frequently allow of enough rise after harvest to prevent reseeding the following season4 8,neutralising0 ,black ,alkali4--,since so little carbonate of soda as one-tenth of one per cent may suffice to render some soils uncultivable1 it frequently happens that its mere transformation into the sulfate is sufficient to remove all stress from alkali4 ,gypsum 7land plaster7 is the cheap and effective agent to bring about this transformation1 provided water be also present4 ,the amount required per acre will1 of course1 vary with the amount of salts in the soil1 all the way from a few hundred pounds to several tons in the case of strong alkali spots2 but it is not usually necessary to add the entire quantity at once1 provided that sufficient be used to neutralize the sodic carbonate near the surface1 and enough time be allowed for the action to take place4 ,in very wet soil1 and when much gypsum is used1 this may occur within a few days2 in merely damp soils in the course of months2 but usually the effect increases for years1 as the salts rise from below4 ,the effect of gypsum on black-alkali land is often very striking1 even to the eye4 ,the blackish puddles and spots disappear1 because the gypsum renders the dissolved humus insoluble and thus restores it to the soil4 ,the latter soon loses its hard1 puddled condition and crumbles and bulges into a loose mass1 into which water now soaks freely1 bringing up the previously depressed spots to the general level of the land4 ,on the surface thus changed1 seeds now germinate and grow without hindrance2 and as the injury from alkali occurs at or near the surface1 it is usually best to simply harrow in the plaster1 leaving the water to carry it down in solution4 ,soluble phosphates present are decomposed so as to retain finely divided1 but less soluble earth phosphates in the soil4 ,it must not be forgotten that this beneficial change may go backward if the land thus treated is permitted to be swamped by irrigation water or otherwise4 ,under the same conditions naturally white alkali may turn black 7see above1 chapter #bb1 p4 #dea74 ,of course1 gypsum is of no benefit whatever on soils containing no 8black0 alkali1 but only 78white07 ,glauber's and common salt4 ,removing the ,salts from the ,soil4--,in case the amount of salts in the soil should be so great that even the change worked by gypsum is insufficient to render it available for useful crops1 the only remedy left is to remove the salts1 partially or wholly1 at least from the surface of the land4 ,three chief methods are available for this purpose4 ,one is to remove the salts1 with more or less earth1 from the surface at the end of the dry season1 either by sweeping or by means of a horse scraper set so as to carry off a certain depth of soil4 ,thus sometimes in a single season one-third or one-half of the total salts may be got rid of1 the loss of a few inches of surface soil being of little moment in the deep soils of the arid region4 ,another method affording partial relief is to flood the land for a sufficient length of time to carry the alkali three or more feet below the surface1 then carefully preventing its re-ascent by suppressing evaporation 7see this chapter1 p4 #dee7 as much as possible4 ,the best of all1 the final and universally efficient remedy1 is to leach the alkali salt out of the soil into the country drainage2 supplementing by irrigation water what is left undone by the deficient rainfall4 ,it is not practicable1 as many suppose1 to wash the salts off the surface by a rush of water1 as they instantly soak into the ground at the first touch4 ,nor is there any certain relief from allowing the water to stand on the land and then drawing it off2 in this case also the salts soak down ahead of the water1 and the water standing on the surface remains almost unchanged4 ,in very pervious soils and in the case of white alkali1 the washing-out can often be accomplished without special provision for underdrainage1 by leaving the water on the land sufficiently long4 ,but the laying of regular underdrains greatly accelerates the work1 and renders success certain4 ,leaching-,down4--,in advance of underdrainage1 it is quite generally feasible1 where the land has been leveled and diked for irrigation by surface flooding1 to leach the salts out of the first three or four feet by continued flooding1 thus taking them out of reach of the crop roots1 or at all events giving the seed an opportunity to escape injury from alkali4 ,this plan is especially effective in the case of alfalfa1 the young seedlings of which are very sensitive1 while the grown plant is rather resistant4 ,in order to obtain this relief so as to know what is being accomplished1 the farmer should ascertain beforehand how fast water will soak down in his ground2#agd for in heavy clay soils1 and especially in those containing black alkali1 the soakage is sometimes so slow that the upward diffusion of the salts keeps pace with the downward soakage2 in which case nothing is accomplished by flooding1 and underdrainage is the only remedy4 ,but in most soils of the arid region flooding from three days to a week will remove the alkali beyond reach of the roots of ordinary crops4 ,if subsequently irrigation is done by means of deep furrows1 the alkali salts may be either kept at a low level continuously1 or if the land be at all pervious1 the alkali may ultimately be permanently leached out into the subdrainage by farther flooding4 ,when the alkali has not accumulated near the surface to any great extent1 irrigation by deep furrows may1 alone1 afford all the relief needed4 #agd ,see p4 #bdb1 ,chap4 #ac4 ,illustration3 ,,fig4 #ga4--,lemon ,orchard ,affected by ,alkali2 ,before ,deep ,irrigation4 ,in the case illustrated by figures #ga and #gb1 irrigation by shallow furrows with water too strongly charged with salts had so far added to the natural alkali-content of the land that the lemon trees were being defoliated4 ,upon the advice of the ,california ,station the deep-furrow system was adopted1 and within two years the results were as shown in figure #gb1 the salts having been carried down and diluted so as to become harmless4 ,underdrainage the ,final and ,universal ,remedy for ,alkali4--,when we underdrain an alkali soil1 we adopt the very means by which the existence of alkali lands in the humid regions is wholly prevented2 the leaching-out of the soluble salts formed in soil-weathering as fast as they are formed4 ,the long and abundant experience had with underdrainage in reclaiming saline sea-coast lands1 applies directly and cogently to alkali lands4 ,it is the universal remedy for all the evils of alkali1 and its only drawback is the first expense1 and the necessity for obtaining an outlet for the drain waters1 which cannot always be had on the owner's land4 ,hence it requires co-operation or legislation to render the great improvement of underdrainage feasible4 ,such legislation is well established in the old world1 and has been enacted in several states even of the humid region4 ,where irrigation is practiced as a matter of necessity1 underdrainage is a correlative necessity1 both to avoid the evils of over-irrigation and to relieve the land of noxious alkali salts4 ,illustration3 ,,fig4 #gb4--,the ,above ,orchard after ,alkali was ,driven ,down by ,deep ,irrigation1 followed by ,cultivation4 ,the drainage law now existing in ,california does not go farther than to authorize the formation of drainage districts1 within which the necessary taxes may be levied2 and there is some difficulty in securing popular action4 ,but bitter experience will doubtless in time compel unanimity1 such as now exists1 e4 g41 in ,illinois1 where drainage is not nearly so urgently needed as it is in the irrigation states4 ,possible ,injury to ,land by ,excessive ,leaching4--,it should not be forgotten1 however1 that excessive leaching of underdrained land by flooding is liable to injure the soil in two ways3 first1 by the removal of valuable soluble plant-food2 and further1 by rendering the land less retentive of moisture1 such retention being favored by the presence of small amounts of alkali salts1 not sufficient to injure crops4 ,after the salts have been carried down to a sufficient depth to prevent injury to annual crops1 and with proper subsequent attention to the prevention of surface evaporation1 the flooding will not need to be repeated for several years4 ,thus in many soils excellent crops may be grown even in strong alkali land1 pending the establishment of permanent drainage systems4 ,the importance of thoroughly washing the alkali deeply into the soil before the seed is planted1 and keeping it there by proper means until the foliage of the plant shades the soil sufficiently to prevent the rise of moisture and alkali1 is well illustrated in fields in the region of ,bakersfield1 ,cal41 where alfalfa is now growing in soils once heavily charged with alkali4#age ,from one of these fields samples of soil were taken where the alkali was supposed to be strongest beneath the alfalfa1 and also from an adjoining untreated alkali spot1 which was said to represent conditions before alfalfa was planted4 ,the results are given in pounds per acre in four feet depth4 ,sulfate4,carbonate4 ,common ,total ,salt4 ,alkali4 ---------------------------------------- ---------------------- ,alkali spot before alfalfa was planted #fj1abj #gbj #age1hdj #bcf1fhj ,alfalfa field2 alkali washed down #ad1djj #a1jdj #ah1fdj ---------------------------------------- ---------------------- ,here the surface foot of the natural soil contained nearly #adj1jjj pounds of common salt1 a prohibitory amount4 ,similar experience has been had near ,yuma1 ,arizona4 #age ,bull4 #acc1 ,cal4 ,expt4 ,sta41 by ,r4 ,h4 ,loughridge4 ,difficulty in ,draining 8,black0 ,alkali ,lands4--,an important exception to the efficacy of draining1 however1 occurs in the case of black alkali in most lands4 ,in this case either the impervious hardpan or 7in the case of actual alkali spots7 the impenetrability of the surface soil itself will render even underdrains ineffective unless the salsoda and its effects on the soil are first destroyed by the use of gypsum1 as above detailed4 ,this is not only necessary in order to render drainage and leaching possible1 but is also advisable in order to prevent the leaching-out of the valuable humus and soluble phosphates1 which are rendered insoluble 7but not unavailable to plants7 by the action of the gypsum4 ,wherever black alkali is found in lands not very sandy1 the application of gypsum should precede any other efforts toward reclamation4 ,trees and vines already planted may be temporarily protected from the worst effects of the black alkali by surrounding the trunks with gypsum or with earth abundantly mixed with it4 ,seeds may be similarly protected in sowing1 and young plants in planting4 ,swamping of ,alkali ,lands4--,it should1 however1 be remembered that the swamping of alkali lands1 whether of the white or black kind1 is fatal not only to their present productiveness1 but also1 on account of the strong chemical action thus induced1 greatly jeopardizes their future usefulness4 ,many costly investments in orchards and vineyards have thus been rendered unproductive1 or have even become a total loss4 ,reduction of ,alkali by ,cropping4--,another method for diminishing the amount of alkali in the soil is the cropping with plants that take up considerable amounts of salts4 ,in taking them into cultivation1 it is advisable to remove entirely from the land the salt growth that may naturally cover it1 notably the greasewoods 7,sarcobatus1 ,allenrolfea71 with their heavy percentage of alkaline ash 7#ab to #bj per cent74 ,crop plants adapted to the same object are mentioned farther on4 ,such crops should also1 of course1 be wholly removed from the land4 ,total ,amounts of ,salts ,compatible with ,ordinary ,crops2 ,tolerance of ,culture ,plants4--,since the amount of alkali that reaches the surface layer is largely dependent upon the varying conditions of rainfall or irrigation1 and surface evaporation1 it is difficult to foresee to what extent that accumulation may go1 unless we know the total amount of salts present that may be called into action4 ,this1 as already explained1 can ordinarily be ascertained by the examination of one sample representing the average of a soil column of four feet4 ,by calculating the figures so obtained to an acre of ground1 we can at least approximate the limits within or beyond which crops will succeed or perish4 ,applying this procedure to the cases represented in the diagrams 7pp4 #dcd1 #deb1 chapter #bb7 and estimating the weight of the soil per acre-foot at #d1jjj1jjj pounds1 we find in the land on which barley refused to grow the figures #cb1dgj and #dc1ffj pounds of total salts per acre1 respectively corresponding to #j4bjc per cent for the first figure 7the second1 representing only the two surface feet1 is not strictly comparable74 ,for the land on which barley gave a full crop1 we find for the ,may sample #be1eej pounds1 equivalent to #j4aei per cent for the whole soil column of four feet4 ,it thus appears that for barley the limits of tolerance lie between the above two figures4 ,it should be noted that in this case a full crop of barley was grown even when the alkali consisted of fully one-half of the noxious carbonate of soda2 proving that it is not necessary in every case to neutralize the entire amount of that salt by means of gypsum1 which in the present case would have required about #i tons of gypsum per acre--a prohibitory expenditure4 ,relative ,injuriousness of the ,several ,salts4--,of the three sodium salts that usually constitute the bulk of 8alkali10 only the carbonate of soda is susceptible of being materially changed by any agent that can practically be applied to land4 ,so far as we know1 the salt of sodium least injurious to ordinary vegetation is the sulfate1 commonly called ,glauber's salt1 which ordinarily forms the chief ingredient of 8white0 alkali4 ,thus barley is capable of resisting about five times more of the sulfate than of the carbonate1 and quite twice as much as of common salt4 ,since the maximum percentage that can be resisted by plants varies materially with the kind of soil1 it is difficult to give exact figures save with respect to particular cases4 ,for the sandy loam of the ,tulare substation1 ,california1 for instance1 the maximum for cereals may be approximately stated to be one-tenth of #a per cent for salsoda2 a fourth of #a per cent for common salt2 and from forty-five to fifty one-hundredths of one per cent of ,glauber's salt4 ,for clay soils the tolerance is in general markedly less1 especially as regards the salsoda2 since in their case the injurious effect on the tilling qualities of the soil1 already referred to1 is superadded to the corrosive action of that salt upon the plant4 ,illustration3 ,,fig4 #gc4--;,alkali curve showing percentage of ,alkali ,salts in field of ,sugar ,beets1 ,oxnard1 ,calif4 ,illustration3 ,,fig4 #gd4--;,beets from corresponding positions in the above field4 ,effect of ,differences in ,composition of ,alkali ,salts on ,beets4--,the marked differences which may occur as the result of even slight variations in the proportions of the several salts is well illustrated in the subjoined diagram of observations made by ,dr4 ,g4 ,w4 ,shaw1 of the ,cal4 ,expt4 station1 upon beet fields in the neighborhood of ,oxnard1 ,cal4 ,the lands lie not far from the seashore1 and saline water underruns them for considerable distance inland4 ,the soil and subsoil are quite sandy1 so that it takes irrigation water only about seven hours to penetrate from the surface to bottom water at seven feet depth4 ,the land on which these observations were made are apparently level to the eye1 though probably the alkali belts on which the sugar beets were 8poor0 are slightly depressed swales4 ,it will be noted that here the beets were 8good0 where the sulfate 7,glauber's salt7 ranged up to 4#h1 with 4#aj to 4#bj of common salt2 but that so soon as the latter rose above 4#bj1 the beets were poor despite the low percentage of ,glauber's salt2 then became 8good0 again so soon as the common salt fell below 4#bj1 although the ,glauber's salt increased4 ,,tolerance ,,of ,,various ,,crop ,,plants4 ,the following table1 compiled by ,dr4 ,r4 ,h4 ,loughridge mainly from his own observations1#agf gives the details of the tolerance for various culture plants as ascertained at the several experiment substations in ,california1 as well as at other points in that ,state and in ,arizona where critical cases could be found4 ,it is thought preferable to investigate analytically such cases in the field1 rather than to attempt to obtain results from small-scale experiments artificially arranged1 in which sources of error arising from evaporation and other causes are most difficult to avoid4 #agf ,bulletins ,nos4 #abh1 #acc and #adj1 ,calif4 ,expt4 ,station4 ,the table is so arranged as to show the maximum tolerance thus far observed for each of the three single ingredients1 as well as the maximum of total salts found compatible with good growth4 ,in view of the extremely variable proportions between the three chief ingredients found in nature1 this seems to be the only manner in which the observations made can be intelligibly presented1 until perhaps a great number of such data shall enable us to evolve mathematical formul expressing the tolerance for the possible mixtures for each plant4 ,for it is certain that the tolerance-figures will be quite different in presence of other salts1 from those that would be obtained for each salt separately2 or for the calculated mean of such separate determinations1 proportionally pro-rated4 ,it must also be remembered that in all alkali soils1 lime carbonate is abundantly present1 as is1 nearly always1 a greater or less amount of the sulfate 7gypsum74 ,as already stated1 according to the investigations of ,cameron not only these compounds1 but also calcium chlorid1 exert a protective influence against the injury to plant growth from compounds of sodium and potassium4 ,the figures here given can therefore be regarded only as approximations1 subject to correction by farther observation4 ,they are arranged from the highest tolerances downward1 for each of the three ingredients1 as well as for the totals4 ,the latter are not1 of course1 the sums of the figures given in the preceding columns1 but independent data4 ,,highest ,,amount ,,of ,,alkali ,,in ,,which ,,fruit ,,trees ,,were ,,found ,,unaffected4#agg ,arranged from highest to lowest4 ,pounds per acre in four feet depth4 ,sulfates ,carbonate ,chlorid ,total ,alkali4 7,glauber's ,salt74 7,salsoda74 7,common ,salt74 ---------------------------------------- ------------------------- ,grapes #dj1hjj ,grapes #g1eej ,grapes #i1fdj ,grapes #de1gjj ,olives #cj1fdj ,oranges #c1hdj ,olives #f1fdj ,olives #dj1afj ,figs #bd1dhj ,olives #b1hhj ,oranges #c1cfj ,almonds #be1efj ,almonds #bb1gbj ,pears #a1gfj ,almonds #b1djj ,figs #bf1djj ,oranges #ah1fjj ,almonds #a1ddj ,mulberry #b1bdj ,oranges #ba1hdj ,pears #ag1hjj ,prunes #a1cfj ,pears #a1cfj ,pears #bj1ibj ,apples #ad1bdj ,figs #a1abj ,apples #a1bdj ,apples #af1abj ,peaches #i1fjj ,peaches #fhj ,prunes #a1bjj ,prunes #aa1hjj ,prunes #i1bdj ,apples #fdj ,peaches #a1jjj ,peaches #aa1bhj ,apricots #h1fdj ,apricots #dhj ,apricots #ifj ,apricots #aj1jhj ,lemons #d1dhj ,lemons #dhj ,lemons #hjj ,lemons #e1gfj ,mulberry #c1cfj ,mulberry #afj ,figs #hjj ,mulberry #e1gfj ---------------------------------------- ------------------------- #agg ,the several columns of figures are independent of each other2 the 8total0 alkali is not the summation for the three salts in the same line4 ,,other ,,trees4 ---------------------------------------- -------------------- ,klreuteria #ea1jdj ,klreuteria #i1ibj ,or4 ,sycamore #bj1cbj ,eucal4 am4 #cd1gbj ,or4 ,sycamore #c1bjj ,klreuteria #ab1fdj ,or4 ,sycamore #ai1bdj ,date ,palm4 #b1hjj ,eucal4 am4 #b1ifj ,wash4 ,palm #ac1jdj ,eucal4 am4 #b1gbj ,camph4 ,tree #a1dbj ,date ,palm #e1ejj ,wash4 ,palm #a1bjj ,wash4 ,palm #a1jdj ,camph4 ,tree #e1bhj ,camph4 ,tree #cbj ---------------------------------------- -------------------- ,klreuteria #gc1fjj ,or4 ,sycamore4 #db1gfj ,eucal4 am4 #dj1djj ,wash4 ,palm #ae1bjj ,date ,palm #h1cbh ,camph4 ,tree #g1jbj --------------------- ,,small ,,cultures4 ---------------------------------------- --------------------- ,saltbush #abe1fdj ,saltbush #ah1efj ,modiola #dj1hfj ,alfalfa1 old #ajb1dhj ,barley #ab1agj ,saltbush #ab1ebj ,alfalfa1 young #aa1abj ,bur ,clover #aa1cjj ,sorghum #i1fhj ,hairy ,vetch #fc1gbj ,sorghum #i1hdj ,celery #i1fjj ,sorghum #fa1hdj ,radish #h1gbj ,onions #e1haj ,sugar ,beet #eb1fdj ,modiola #d1gfj ,potatoes #e1haj ,sunflower #eb1fdj ,sugar ,beet #d1jjj ,sunflower #e1ddj ,radish #ea1hhj ,gluten ,wheat #c1jjj ,sugar ,beet#agh #aj1bdj ,artichoke #ch1gbj ,artichoke #b1gfj ,barley #e1ajj ,carrot #bd1hhj ,lupin #b1gbj ,hairy ,vetch #c1afj ,gluten ,wheat #bj1ifj ,hairy ,vetch #b1dhj ,lupin #c1jdj ,wheat #ae1abj ,alfalfa #b1cfj ,carrot #b1cfj ,barley #ab1jbj ,grasses #b1cjj ,radish #b1bdj ,goat's ,rue #aj1hhj ,kaffir ,corn #a1hjj ,rye #a1gbj ,rye #i1hjj ,sweet ,corn #a1hjj ,artichoke #a1dhj ,caaigre #i1afj ,sunflower #a1gfj ,gluten ,wheat #a1dhj ,ray ,grass #f1ibj ,wheat #a1dhj ,wheat #a1afj ,modiola #f1hjj ,carrot #a1bdj ,grasses #a1jjj ,bur ,clover #e1gjj ,rye #ifj ,white ,melilot #ddj ,lupin #e1ddj ,goat's ,rue #gfj ,goat's ,rue #afj ,white ,melilot #d1ibj ,white ,melilot #dhj ,caaigre #hj ,celery #d1jhj ,caaigre #abj ,saltgrass #dd1jjj ,saltgrass #acf1bgj ,saltgrass #gj1cfj ---------------------------------------- ---------------------- ,saltbush #aef1gbj ,alfalfa1 old #aaj1cbj ,alfalfa1 young #ac1abj ,sorghum #ha1cfj ,hairy ,vetch #fi1cfj ,radish #fb1hdj ,sunflower #ei1hdj ,sugar ,beet #ei1hdj ,modiola #eb1dbj ,artichoke #db1ifj ,carrot #bh1dhj ,barley #be1ebj ,gluten ,wheat #bd1cbj ,wheat #ag1bhj ,bur ,clover #ag1jjj ,celery #ac1fhj ,rye #ab1dhj ,goat's ,rue #aa1hjj ,lupin #aa1bjj ,caaigre #i1cfj ,onions #ch1dhj ,potatoes #ch1dhj ,saltgrass #cha1aaj ---------------------- #agh ,figures taken from ,bulletin #afi1 ,calif4 ,expt4 ,station1 ,june1 #aije4 ,comments on the ,above ,table4--,considering in this table1 first1 the plants suitable for the stronger class of alkali lands1 it may be said generally that the search for widely acceptable kinds has not been very successful4 ,it is true that cattle will nibble green salt grass 7,distichlis spicata71 but will soon leave it for any dry feed that may be within reach4 ,the enormous amount of salts which it will tolerate in the soil on which it grows1 and the doubtless correspondingly large amount of those salts which it will absorb1 judging from its taste1 sufficiently explain the reluctance of cattle to feed on it to any considerable extent4 ,the same is true of all the fleshy plants that grow on the stronger alkali lands1 and are known under the general designation of 8alkali weeds40 ,when stock unaccustomed to it are forced by hunger to feed on such vegetation to any considerable extent1 disordered digestion is apt to result2 which in such ranges1 however1 is often counteracted by feeding on aromatic or astringent antidotes1 such as the gray sagebrush and the more or less resinous herbage of plants of the sunflower family4 ,in the ,great ,basin region1 lying between the ,sierra ,nevada and the front range of the ,rocky ,mountains1 there are1 aside from the grasses1 numerous herbaceous and shrubby plants that afford valuable pasturage for stock1#agi and some of these grow on moderately strong alkali land2 the same is true in ,california4 ,it is quite possible that some of these will be found to lend themselves to ready propagation for culture purposes as well as they do for restocking the ranges4 ,but thus far none have found wider acceptance1 probably because their stiff branches and upright habit render them inconvenient to handle4 ,it will require more extended experience and experiment before any of these will be definitely adopted for propagation by farmers and stockmen4 #agi ,see ,bulletin ,no4 #af of the ,wyoming ,experiment ,station2 also ,bulletin ,nos1 #b and #ab of the ,division of ,agrostology1 and ,farmers' ,bulletin ,no4 #ajh1 ,u4 ,s4 ,department of ,agriculture4 ,saltbushes1 and ,herbaceous ,crops4 ,australian ,saltbushes4--,experience in ,california indicates that in the more southerly portion of the arid region1 unpalatable native plants may be largely replaced1 even on the ranges1 by one or more species of the ,australian saltbushes 7,atriplex spp471 long ago recommended by ,baron von ,mueller of ,melbourne2 of which one 7,a4 semibaccata7 has proved eminently adapted to the climate and soil of ,california and is readily eaten by all kinds of stock4 ,the facility with which it is propagated1 its quick development1 the large amount of feed yielded on a given area1 even on the strongest alkali land ordinarily found1 and its thin1 flexible stems1 permitting it to be handled very much like alfalfa1 seem to commend it especially to the farmers' consideration wherever better forage plants cannot be grown and the climate will permit of its use4 ,it does not1 however1 resist the severe cold of the interior plateau country1 and is wholly out of place in the ,pacific ,coast region where summer fogs prevail4 ,most of the other ,australian species have an upright1 shrubby habit1 which adapts them better to browsing than to pasture proper4 ,the same is true of the ,argentine species 7,a4 ,cachiyuyum71 which in its native pampas is highly esteemed for that purpose1 and succeeds well in ,california4 ,of other ,australian saltbushes1 ,a4 halimoides1 vesicaria and leptocarpa are the most promising2 the latter is somewhat similar in habit to the semibaccata1 but is not as vigorous a grower4 ,since some of the saltbushes take up nearly one fifth of their dry weight of ash ingredients1#ahj largely common salt1 the complete removal from the land of a five-ton crop of saltbush hay will take away nearly a ton of the alkali salts per acre4 ,this will in the course of some years be quite sufficient to reduce materially the saline contents of the land1 and will frequently render possible the culture of ordinary crops4 #ahj ,analyses made at the ,california station show #ai4cg percent of ash in the air-dry matter of ,australian saltbush4 7,see ,california ,station ,bulletin ,no4 #aje2 ,e4 ,s4 ,r41 vol4 #f1 p4 #gah74 ,analyses of ,russian thistle have been reported showing over #bj per cent of ash in dry matter4 7,see ,minnesota ,sta4 ,bulletin ,no4 #cd2 ,iowa ,sta4 ,bull4 ,no4 #bf2 ,e4 ,s4 ,r41 vol4 #f1 pp4 #eeb-eec74 ,modiola4--,alongside of the saltbushes1 the ,chilean plant ,modiola procumbens1 now generally known as modiola simply1 deserves attention1 as it makes acceptable pasture where alfalfa fails to make a stand on account of alkali4 ,it is a trailing plant with medium-sized1 roundish foliage1 and roots freely at the joints where they touch the ground4 ,unlike the saltbushes it is therefore a formidable weed where it is not wanted2 but as according to ,california experience it resists as much as #eb1jjj pounds of salts per acre1 even when #da1jjj of these is common salt1 it is likely to be useful in many cases1 particularly as an admixture to a saltbush diet for stock1 as it does not absorb as much salt as the latter4 ,it seems best adapted to pasturage4 ,as the table shows that1 once grown to the age of a few years1 alfalfa will resist a percentage of alkali next to the saltbush1 it will generally be worth while1 in lands otherwise adapted to alfalfa1 to prepare the land by leaching-down 7see above7 so as to secure a stand of the more valuable crop4 ,native ,grasses4#aha--,of all known plants that stock will eat somewhat freely1 the tussock grass 7,sporobolus airoides1 of which a figure is given farther on71 a native of the southern arid region1 endures the largest amounts of alkali2 having been found growing well on land containing the enormous amount of nearly half a million pounds of salts per acre1 although it will thrive with only #di1jjj pounds in the soil4 ,what it will do under cultivation has never been fairly tested2 but its bare tussocks1 killed by the excessive browsing of stock1 testify to its acceptableness as forage4 ,it does not seem to absorb excessive amounts of salts4 #aha ,it should be understood that the plants so referred to are exclusively the true grasses1 recognized as such by every child1 and not forage plants generally2 which are sometimes so designated2 not only by farmers1 but by some authors who fail to appreciate the practical importance of the distinction1 which makes it necessary that farmers should be taught to understand it4 ,aside from the alkali grass proper 7,distichlis71 mentioned above1 the so-called rye grass of the ,northwest 7,elymus condensatus7 is probably1 next to the tussock grass1 the most resistant species among the wild grasses4 ,its southern form1 with several others not positively identified1 occupies largely the milder alkali lands of southern ,california4 ,this grass1 though rather coarse1 is regularly cut for hay in the low grounds of ,oregon and ,washington4 ,doubtless some of the indigenous grasses of the interior plateau region and of the great plains east of the ,rocky ,mountains1 such as the buffalo and grama grasses1 as well as several of the wheat grasses 7,agropyron7 and bunch grasses 7,festuca1 ,poa1 ,stipa1 etc47 will prove resistant to larger proportions of alkali than the meadow and pasture grasses of the regions of summer rains4 ,cultivated ,grasses4--,the superficial rooting and fine fibrous roots of the true annual grasses render them1 as a whole1 rather sensitive to alkali2 yet the cereals--barley1 wheat1 rye and oats--resist1 as the table shows1 the average alkali salts to the extent of from #ag1jjj total salts1 with not exceeding #aejj pounds of carbonate1 in the case of the more delicate varieties of wheat1 to over #be1jjj pounds per acre in the case of barley1 which with the gluten wheats and rye seems to have the highest tolerance-figure4 ,the special adaptation of gluten wheats to arid conditions is thus emphasized4 ,the roots of these cereals are comparatively stout1 with thick epidermis4 ,among the cultivated forage grasses proper1 the ,australian variety of the ,english ray 7generally miscalled rye7 grass seems most resistant4 ,the eastern fescues1 ,kentucky blue grass1 and others at home in the humid region are easily injured1 as those who try to maintain lawns on alkali-tainted lands1 or by irrigation with alkali waters1 know to their sorrow4 ,to these grasses common salt and bittern 7magnesium chlorid7 seem to be particularly injurious1 and they tolerate but little 8black alkali40 ,on the rather close-textured soil at ,chino1 ,california1 the loliums1 including the darnel 78,california cheat071 and the ,australian and ,italian ray 78rye07 grasses1 succeed fairly on land containing as much as #f1jjj pounds of 7white7 salts4 ,most other cultivated grasses failed conspicuously alongside of these4 ,it must be remembered that in more loose-textured1 sandy lands than those in which these tests were made1 the above figures for tolerance would probably be increased by #cj percent or more4 ,maize is rather sensitive to alkali1 and suffers even on slightly alkaline land1 owing doubtless to the large development of fine white rootlets near the surface1 so familiar to corn-growers4 ,the ,sorghums1 and especially ,egyptian corn 7durra7 are much less sensitive1 as the table shows1 and are among the first crops to be tried on alkali lands4 ,the related millets share this resistance more or less1 and we often see on cultivated lands in the alkali region fine stands of barnyard grass 7,panicum crusgalli7 of which the variety 787 ,p4 muticum is said by observers of the ,u4 ,s4 ,dept4 of ,agriculture to be specially resistant1 and acceptable to stock4 ,one of the most successful grasses on the light alkali lands near ,chino1 where most of the commonly cultivated grasses fail1 was a near relative of the barnyard grass1 the ,eleusine coracana1 which produces heavy crops of a millet-like grain much relished by poultry1 and also by stock4 ,this grass1 largely grown in ,egypt1 has succeeded well all over the ground whose alkali content ranges up to #ab1jjj pounds per acre1 but failed where the salts reached #ch1hdj pounds in the surface foot4 ,next to this1 in point of success1 were the pearl millet 7,pennisetum typhoideum7 and teosinte1 ,hungarian brome grass1 and ,japanese millet1 on land containing about #i1jjj pounds of 7chiefly 8white07 salts per acre4 ,other ,herbaceous ,crops4 ,legumes4--,both the natural growth of alkali lands and experimental tests seem to show that this entire family 7peas1 beans1 clovers1 etc47 are among the more sensitive and least available wherever black alkali exists2 while fairly tolerant of the white 7neutral7 salts4 ,apparently a very little salsoda suffices to destroy the tubercle-forming organisms that are so important a medium of nitrogen-nutrition in these plants4 ,excepting the melilots1 alfalfa with its hard1 stout and long taproot1 seems to resist best of all these plants4 ,as a general thing1 taprooted plants1 when once established1 resist best1 for the obvious reason that the main mass of their feeding roots reaches below the danger level4 ,another favoring condition1 already alluded to1 is heavy foliage and consequent shading of the ground2 alfalfa happens to combine both of these advantages4 ,there has been some difficulty in obtaining a full stand of alfalfa in the portion of the ,chino substation tract containing from #djjj to #fjjj pounds of 7largely black7 alkali salts per acre2 but once obtained1 it has done very well4 ,the only other plant of this family that succeeds well on this land1 and even 7at ,tulare7 on soil considerably stronger 7probably between #bj1jjj and #cj1jjj pounds7 are the two melilots1 ,m4 indica1 and alba2 the latter 7the ,bokhara clover7 is a forage plant of no mean value in moist climates1 but somewhat restricted in its use in the arid region because of the very high aroma it develops1 especially in alkali lands2 so that stock will eat only limited amounts1 best when intermixed with other forage1 such as the saltbushes4 ,the yellow melilot is highly recommended by the ,arizona ,experiment ,station as a green-manure plant for winter growth2 but farther north it is a summer-growing plant only1 and is refused by stock4 ,as already stated1 very few plants belonging to this family are naturally found on alkali lands1 and attempts to grow them1 even where only ,glauber's salt is present1 have been but very moderately successful4 ,for most of the legumes the limit of full success seems to lie between #cjjj and #djjj pounds to the acre4 ,a marked exception1 however1 occurs in the case of the hairy vetch1 as shown in the table1 where it is credited1 on the basis of repeated experiments1 with a tolerance of nearly #gj1jjj pounds4 ,this amount was attained1 however1 in rather sandy soils4 ,probably some of the ,algerian vetches will likewise prove more resistant than those which are natives of humid climates4 ,mustard ,family4--,as in the case of the legumes1 wild plants of the mustard family are rare on alkali lands2 and correspondingly1 the cultivated mustard1 kale1 rape1 etc41 fail even on land quite weak in alkali4 ,their limit of tolerance seems to lie near #d1jjj to #e1jjj pounds per acre even of white salts4 ,hence turnips and radishes do not flourish on alkali lands4 ,sunflower ,family4--,several of the hardiest of the native 8alkali weeds0 belong to the sunflower family1 and the common wild sunflowers 7,helianthus californicus and ,h4 annuus7 are common on lands pretty strongly alkaline4 ,the cultivated ,russian sunflower1 as the table shows1 resists the effects of nearly #fj1jjj pounds of total alkali1 of which #eb1fdj pounds was sulfate 7,glauber's salt71 and #eddj common salt4 ,this1 it will be seen1 is a very high tolerance1 so that this sunflower1 yielding such excellent poultry feed1 is very widely available4 ,correspondingly1 the 8,jerusalem artichoke10 itself a sunflower1 is among the available crops on moderately strong alkali soils2 and so1 doubtless1 are other members of the same relationship not yet tested1 such as the true artichoke1 salsify1 etc4 ,chicory1 belonging to the same family1 yielded roots at the rate of twelve tons per acre1 on land of the ,chino tract containing about #h1jjj pounds of salts per acre4 ,root ,crops4--,it seems to be generally true that root crops suffer in quality1 however satisfactory may be the quantity1 harvested on lands rich in salts1 and especially in chlorids 7common salt74 ,it was noted at the ,tulare substation 7,california7 that the tubers of the artichoke were inclined to be 8squashy0 in the stronger alkali land1 and failed to keep well2 the same was true of potatoes1 which were very watery2 and also of turnips and carrots4 ,it is a fact well known in ,europe1 that potatoes manured with kainit 7chlorids of potassium and sodium7 are unfit for the manufacture of starch1 and are generally of inferior quality4 ,but this is found not to be the case when1 instead of the chlorids1 the sulfate is used2 hence the advice1 often repeated by the ,california station1 that farmers desiring to use potash fertilizers should call for the 8high-grade sulfate0 instead of the cheaper kainit1 which adds to the injurious salts already so commonly present in lowland soils of the arid region4 ,such root crops are1 however1 available for stock feed4 ,the common beet 7including the mangel-wurzel7 is known to succeed well on saline seashore lands1 and it maintains its reputation on alkali lands also4 ,being especially tolerant of common salt1 it may be grown where other crops fail on this account2 but the roots so grown are strongly charged with common salt1 and have1 as is well known1 been used for the purpose of removing excess of the same from sea-coast-marsh lands4 ,such roots are wholly unfit for sugar-making4 ,it is quite otherwise with ,glauber's salt 7sodium sulfate72 and as this is very commonly predominant in alkali lands1 either before or after the gypsum treatment1 this fact is of great importance1 for it frequently permits of the successful growing of the sugar beet2 as has been abundantly proved at the ,chino ranch1 where land containing as much as #fj1jjj pounds of salts1 mostly this compound1 has yielded roots of very high grade1 both as to sugar percentage and purity4 ,but the analyses of the ,oxnard soil show that more than #aj1jjj pounds of common salt will be required to render sugar beets unsatisfactory for sugar-making4 ,passing to stem crops1 we find that asparagus1 originally itself a denizen of the sea-board1 resists considerable amounts 7not yet exactly determined7 of common salt as well as of ,glauber's salt4 ,it is even claimed that when grown with a dressing of common salt the asparagus is more tender and savory4 ,but it is quite sensitive to 8black alkali10 which must be neutralized with gypsum to render it harmless4 ,celery did well with #ac1fdj pounds1 of which nearly #aj1jjj was common salt4 ,but with #cj1jjj pounds the plants were killed4 ,rhubarb was a conspicuous failure1 even in the weak and mostly 8white0 alkali lands of the ,chino station tract4 ,textile ,plants4--,japanese hemp1 while young1 seemed to have a hard struggle with the alkali1 but at the end of the season stood eight feet high4 ,the ramie plant1 also1 will bear moderately strong alkali1 apparently somewhat over #ab1jjj pounds per acre4 ,flax has not been tested in cultivation2 but the wide distribution of wild flax all over the arid portions of the ,states of ,oregon and ,washington1 would seem to indicate that it is not very sensitive4 ,another textile plant1 the ,indian mallow 7,abutilon avicennae71 was found to fail on the ,chino alkali soil4 ,but its close relative1 cotton1 does not seem to be specially sensitive1 according to the experience had with it in the ,merced river bottom in ,california2 and its culture is extensive in ,egypt1 where no particular care seems to be exercised in selecting the land for the crop4 ,it is just possible that the saline content of the soil has in ,california1 as well as in the ,atlantic sea-islands1 contributed to the superior length of the fiber shown in the measurements made during the ,census work of #ahhj4ahb #ahb ,report on ,cotton ,culture2 #ajth ,census of the ,united ,states1 vol4 #e1 pp4 #bc to #cd4 ,tolerance of ,shrubs and ,trees4 ,grapevines4--,the ,european grape1 ,vitis vinifera1 is quite tolerant of white or neutral alkali salts1 and will resist even a moderate amount of the black so long as no hardpan is allowed to form4 ,at the ,tulare substation it was found that grapevines did well in sandy land containing #ce1bcj pounds of alkali salts1 of which one half was ,glauber's salt1 #i1fdj pounds carbonate of soda1 #g1eej pounds of common salt1 and #gej pounds nitrate of soda4 ,they were badly distressed where1 of a total of #cg1jbj pounds of alkali salts1 #be1fbj pounds was carbonate of soda2 while where the vines had died out1 there was found a total of #gc1icj pounds1 with #cg1bhj pounds of carbonate4 ,the ,european vine1 then1 is considerably more resistant of alkali even in its worst 7black7 form1 than barley and rye1 at least on sandy land2 and it seems likely that the native grapevines of the ,pacific coast1 californica1 and arizonica1 would resist even better2 a point still under experiment4 ,experience1 however1 has shown that vines rapidly succumb when by excessive irrigation the bottom water is allowed to rise1 increasing the amount of alkali salts near the surface1 and shallowing the soil at their disposal4 ,such over-irrigation has been a fruitful cause of injury to vineyards in the ,fresno region1 and would doubtless if practiced kill most of the vines at the ,tulare substation1 which are now flourishing4 ,in such cases1 sometimes the formation of hardpan is followed by that of a concentrated alkaline solution above it1 strong enough to corrode the roots themselves1 and not only killing the vines1 but rendering the land unfit for any agricultural use whatsoever4 ,the swamping of alkali lands1 whether of the white or black kind1 is not only fatal to their present productiveness1 but1 on account of the strong chemical action thus induced1 greatly jeopardizes their future usefulness4 ,many costly investments in orchards and vineyards have thus been rendered unproductive1 or have even become a total loss4 ,it should be remembered in this connection that as the roots of vines will1 when unobstructed1 go to depths of fifteen and even twenty feet1 a subsequent rise of the bottom water from leaky irrigation ditches will drown out the ends of the deep roots and thus cause the whole root system to become diseased1 inevitably resulting in unproductiveness1 if not death1 of the vine4 ,citrus ,trees4--,although the high figure of nearly #bg1jjj pounds for the tolerance of citrus trees1 as given in the table1 seems to place them rather high on the list1 such high tolerance actually occurs only in very sandy soils1 and when common salt is in small proportion4 ,generally speaking1 the citrus tribe are rather sensitive to alkali salts1 and more especially to common salt4 ,in fact1 as to the high tolerance-figure given in the table1 observed in sandy land1 the alkali there contained only a trace of common salt4 ,young seedling trees are particularly sensitive2 so that it is often difficult to obtain a stand even when1 later on1 the feeding roots descend beyond the reach of injury4 ,in the close-textured lands of ,chino1 young trees hardly maintained life with more than #e1jjj pounds of total salts4 ,near ,riverside1 full-grown trees perished under the influence of bottom water containing #j4be1 or #adf grains of salt per gallon1 which impregnated the ground2 corresponding to about #i1jjj pounds per acre in four feet4 ,in the sandy loam lands near ,corona1 trees eight years old suffered severely when by irrigation with alkali-water the alkali-content of the land reached #aa1jjj pounds per acre2 as illustrated in ,figs4 ,nos4 #dd1 and #de4 ,at another point in the same region1 two representative trees were selected for comparison1 five rows apart on land absolutely identical2 one of these retained its leaves1 though suffering1 the other was completely leafless4 ,the leaching of the alkali to the depth of four feet gave the following results1 calculated to pounds per acre3 ,sulfates4 ,carbonates4 ,chlorids4 ,total4 ,poor tree #d1gbj #a1fhj #b1ebj #h1ibj ,better tree #d1abj #b1cfj #gbj #g1bjj ,here it is apparently the excess of common salt to which the difference is due1 and this despite the higher content of carbonate of soda in the soil bearing the better tree4 ,on the other hand1 at the ,tulare substation orange trees 7sour stock7 maintain vigorous growth and good bearing in a very sandy tract which to the depth of seven feet showed an aggregate content of #bf1hdj pounds of salts 7or #bb1ghj to four feet depth72 but which is never irrigated4 7,see diagram ,no4 #ff74 ,the salts in this case consists wholly of sulfate and carbonate of soda in the ratio of fifty-four to forty-two1 implying the presence of nearly #ab1jjj pounds of salsoda within reach of the tree roots2 yet in the absence of common salt1 no perceptible injury or even stress upon the trees has been noted4 ,according to observations made in ,san ,diego county1 ,calif41 lemon trees are even more sensitive to common salt than oranges1 since a total content of #h1jjj pounds per acre1 about one-third of which was common salt1 seemed to render the trees wholly unprofitable4 ,in view of these facts1 showing that common salt is the portion of alkali by far most injurious to citrus trees1 great care should be taken in the use of irrigation waters to exclude those charged with that compound2 and also to avoid locating citrus orchards on land already impregnated with common salt4 ,the olive tree1 as the table shows1 is among the most resistant to alkali salts1 approaching the grape in this respect4 ,this might have been anticipated from its extended culture in the arid regions of the old world1 including ,palestine and northern ,africa1 where alkali lands abound4 ,it is probable that the figure given in the table does not yet show the extreme limit of its endurance4 ,california experience with the date palm1 as the table shows1 credits it with an endurance not exceeding #hcbj pounds of total salts4 ,this is doubtless an underestimate1 for in the ,sahara desert and ,egypt it is credited with being the culture which will succeed in stronger alkali than any other cultural plant2 and1 according to ,mr4 ,means of the ,united ,states ,department of ,agriculture1 it is sometimes irrigated with water containing as much as #bjj grains of salts per gallon4 ,it should be remembered1 however1 that these trees always grow in very sandy lands2 and in the desert regions it is often grown below the surface of the ground1 so as to render it wholly independent of the alkali accumulations on the surface4 ,the extreme limit of its endurance must therefore remain in doubt until more extended experiments have made more definite data available4 ,deciduous ,orchard ,trees4 ,among deciduous orchard trees1 strangely enough1 the almond stands alongside of the fig in alkali-resistance1 as indicated in the table4 ,the peach seems to be much more sensitive1 ranking near the apricot and prune1 whose tolerance is less than half as high4 ,that the pear and apple1 generally counted among the more northern fruits in the humid region1 should excel these stone fruits in endurance of alkali1 is rather unexpected2 and the figures concerning the whole group of these rosaceous fruits admonish us that it is unsafe to predict1 without trial1 what may be the outcome of culture tests4 ,thus plum trees1 apparently in good condition1 sometimes suddenly begin to fail when starting to bear2 the fruit appears normal on the outside for a time1 but the pit fails to form1 being at times flattened out like a piece of pasteboard2 and the fruit does not mature4 ,yet there is no observable injury to the base of the trunk1 or to the roots4 ,on the other hand1 pears do well even when the outside bark around the root-crown is blackened by the action of the alkali salts4 ,but #ch1jjj pounds1 even of sulfate1 proves too much for the pear4 ,the quince appears to be materially more resistant than the apple or pear4 ,it probably ranges alongside of the fig1 the soil-adaptations of which it shares in other respects also4 ,the ,english walnut resents even a slight taint of black alkali2 but is fairly tolerant of 8white0 salts1 as is shown in the peculiarly suitable light loam soils on the lower ,santa ,clara river1 in ,ventura county1 as well as in ,orange county1 ,california4 ,close figures for the limits of alkali tolerance in the case of deciduous orchard trees cannot easily be given or determined1 owing to the difficulties inherent in the differences of root penetration in the several soils and localities2 as well as the fact already alluded to1 that in close-textured soils the tolerance is in general decidedly less than in sandy lands4 ,hence the figures in the table must be taken as more nearly representing relative tolerances1 rather than absolute data to be applied in every case4 ,as regards the stone fruits1 it should be remembered that the ,myrobalan root1 being at home in ,asia ,minor1 where alkali abounds1 should when practicable be used wherever alkali conditions exist1 in preference to all but the almond1 which seems to resist well1 even on its own root1 but has not as wide a range of adaptations as a grafting stock as the myrobalan4 ,while most of the other stone fruits at the ,tulare substation were on myrabalan roots1 the stock of those in outside orchards was mostly in doubt4 ,it is also to be kept in mind that different varieties of the same fruit--e4 g41 pears and apples--show a not inconsiderable variation in their resistance4 ,timber and ,shade ,trees4 ,of trees1 forest and shade1 suitable for alkali lands1 some native ones call for mention4 ,one is the ,california white or valley oak 7,quercus lobata71 which forms a dense forest of large trees on the 7almost throughout somewhat alkaline7 delta lands of the ,kaweah ,river in ,california1 and is found scatteringly all over the ,san ,joaquin ,valley4 ,unfortunately this tree does not supply timber valuable for aught but firewood or fence posts1 being quite brittle4 ,the native cottonwoods1 while somewhat retarded and dwarfed in their growth in strong alkali1 are quite tolerant of the white salts1 especially of ,glauber's salt4 ,as they usually grow near to the water1 their tolerance for alkali salts is difficult to ascertain4 ,of other trees1 the oriental plane1 or sycamore1 and the black locust have proved the most resistant in the alkali lands of the ,san ,joaquin ,valley2 and the former being a very desirable shade tree1 it should be widely used throughout the regions where alkali prevails more or less4 ,the ailantus is about equally resistant1 and but for the evil odor of its flowers1 deserves strong commendation4 ,of the eucalypts1 the narrow-leaved ,eucalyptus amygdalina 7one of the 8red gums07 and the closely related viminalis1 seem to be least sensitive1 and in some cases have grown in alkali lands as rapidly as anywhere4 ,the rostrata1 as well as the pink flowered variety of sideroxylon1 are now doing about as well as the amygdalina at ,tulare1 where at first they seemed to suffer4 ,the common blue gum1 globulus1 is much more sensitive4 ,of the ,acacias1 the tall-growing ,a4 melanoxylon 78black acacia07 resists pretty strong alkali1 even on stiff soil2 as can be seen at ,tulare and ,bakersfield1 ,california1 where there are trees nearly two feet in diameter4 ,the beautiful ,a4 lophantha 7,albizzia7 has in plantings made along the ,san ,joaquin ,valley railroad shown considerable resistance1 likewise2 but it is quite sensitive to frost4 ,of other ,australian trees1 one of the ,australian 8pines10 7,casuarina equisetifolia71 is doing well on fairly strong alkali land in the ,san ,joaquin ,valley4 ,a remarkably alkali-resistant shrub or small tree is the pretty ,klreuteria paniculata from ,china1 which at ,tulare is growing in some of the strongest alkali soil of the tract4 ,unfortunately it is available mainly for ornamental purposes2 its wood1 while small1 is very hard and makes excellent fuel4 ,of trees indigenous to the ,atlantic and ,east ,central ,united ,states1 the ,tulip tree1 the ,linden1 and most other trees of the humid region1 including the ,english oak 7,quercus pedunculata7 become stunted in alkali soils4 ,the honey locust1 being particularly adapted to calcareous lands1 does moderately well on alkali lands1 but its thorns and imperfect shade render it not very desirable4 ,the black locust and the elms have on the whole done best4 ,the eastern maples are not successful2 but the ,california maple 7,acer macrophyllum7 and the box elder 7,negundo californica7 have done fairly well in the lighter alkali lands of the ,san ,joaquin ,valley4 ,the ,conifers--,pines1 firs1 cedars1 cypress1 etc41 are very sensitive to black alkali and will not endure much even of the 8white0 salts4 ,even the native juniper of the mesas carefully adheres to the portions--breaks and upper slopes1 hilltops1 etc4--which are more or less leached by the scanty rains of these regions4 ,,inducements ,,toward ,,the ,,reclamation ,,of ,,alkali ,,lands4 ,the expense involved in the reclamation of strong alkali lands naturally gives rise to the question whether adequate advantages are likely to be derived from such expenditure2 specially when the last resort--underdraining and leaching--has to be adopted4 ,those familiar with the alkali regions are aware how often the occurrence of alkali spots interrupts the continuity of fields and orchards1 of which they form only a small part1 but enough to mar their aspect and cultivation4 ,their increase and expansion under irrigation frequently renders their reclamation the only alternative of absolute abandonment of the investments and improvements made1 and from that point of view alone it is of no slight practical importance4 ,moreover1 the occurrence of vast continuous stretches of alkali lands within the otherwise most eligibly situated valley lands of the irrigation region forms a strong incentive towards their utilization4 ,illustration3 #ast year1 #b;d year1 #c;d year1 ,fourth year--#db bushels4 ,,fig4 #ge4--,wheat grown on black alkali land at ,tulare ,substation1 ,california1 showing improvement in successive years of reclamation treatment4 ,there is1 however1 a strong intrinsic reason pointing in the same direction1 namely1 the almost invariably high and lasting productiveness of these lands when once rendered available to agriculture4 ,this is foreshadowed by the usually heavy and luxuriant growth of native plants around the margins and between alkali spots 7see fig4 #fj72 i4 e41 wherever the amount of injurious salts present is so small as not to interfere with the utilization of the abundant store of plant-food which1 under the peculiar conditions of soil-formation in arid climates1 remains in the land instead of being washed into the ocean4 ,extended comparative investigations of soil composition1 as well as the experience of thousands of years in the oldest settled countries of the world1 demonstrate this fact and show that so far from being in need of fertilization1 alkali lands usually possess extraordinary productive capacity whenever freed from the injurious influence of the excess of useless salts left in the soil in consequence of deficient rainfall4 7,see analyses1 chapter #bb1 pp4 #dcf1 #dcg74 ,illustration3 ,,fig4 #gf4--;,grains grown on alkali land at ,tulare ,station1 ,california4 ,among many striking examples of the results of such reclamation1 is that represented in the annexed figure 7#ge71 of grain grown on strong alkali land1 before and after reclamation treatment4 ,on the original land even 8alkali weeds0 would hardly grow2 while afterward a wheat crop representing forty-two bushels per acre was grown4 ,additional illustrations are shown in the second figure 7#gf71 showing crops of wheat and barley as grown on partly reclaimed land at the ,tulare substation4 ,while it is certainly true that when rightly treated1 alkali lands can be rendered profusely and lastingly productive1 yet close attention and constant vigilance are needed so long as the salts remain in the soil2 and no one not determined to give such land such full attention1 should undertake to cultivate it4 ,,part ,,fourth4 ,,soils ,,and ,,native ,,vegetation4 ,,chapter ,,xxiv4#ahc ,,the ,,recognition ,,of ,,character ,,of ,,soils ,,from ,,their ,,native ,,vegetation2 ,,mississippi4 ,climatic and ,soil-,conditions4--,next to climatic conditions1 chief among which are temperature and moisture1 the physical and chemical nature of the soil and subsoil is the most potent factor in determining the natural vegetation of any region4 ,the limitations we observe in the adaptation of cultivated lands to certain crops1 even with artificial help1 must be much more strongly pronounced when no such aid is given1 and the struggle for the survival of the fittest is continued1 subject only to seasonal variations1 for thousands of years4 ,it is obvious that within the limits of the regional flora1 the natural vegetation of any tract represents the best adaptation of plants to soils1 in the results of long periods of the struggle for existence between competing species2 the survivors being those best adapted to the entire environment4 #ahc ,the special object of this chapter as a whole has seemed to the writer to require a repetition of much that is already said in the preceding chapters4 ,in countries uninhabited by man the chief conditions outside of the direct influence of climate and soil that may materially affect the results of the competition are connected with the animal creation2 and within the latter1 insects are probably the most influential1 beneficially in the part they play in the fertilization of flowers1 injuriously in their role as parasites4 ,since in the absence of man1 the effects of fire would ordinarily be conditioned upon the occurrence of thunderstorms1 its effects would then properly come under the head of climatic influences4 ,but while these and some other disturbing factors must not be forgotten in considering the relations of soils to the natural vegetation borne by them1 the common consensus of mankind has long recognized the intimate connection existing between the two1 and has everywhere made it the basis of at least a general estimate of the agricultural value of the land concerned4 ,,natural ,,vegetation ,,the ,,basis ,,of ,,agricultural ,,land ,,values ,,in ,,the ,,united ,,states4#ahd ,in countries long settled1 as in ,europe1 where the nature of the original forest is unknown or a matter of tradition only1 the adaptations of the several kinds of land to culture plants and forest trees has been gradually ascertained by cultural experience1 and their designations1 values and uses determined accordingly4 ,in the ,united ,states1 the character of the original forest growth is mostly in evidence1 or is definitely known by tradition1 even in the older states4 ,west of the ,alleghenies1 there is as yet little difficulty in this regard1 partly because even where the original forest growth has disappeared its character remains on record1 the assessed land values being very commonly based upon the tree growth of the wild land4 ,in the ,southern ,states especially1 the classification of uplands into 8pine lands0 and 8oak lands0 is universal1 and is associated with certain limits of valuation1 both by assessors and purchasers4 ,within each of these two classes1 however1 there are well-defined gradations of cultural value according to the kind 7species7 e4 g41 of pine or oak that occupies the ground1 either alone1 or in intermixture with other trees whose presence or absence is considered significant4 ,in the case of 8bottoms0 or alluvial lands1 corresponding distinctions and classifications obtain2 we hear of hickory1 beech1 gum1 and cherry bottoms1 hackberry hammocks1 etc4 each name being associated with certain cultural values or peculiarities of soil1 well understood by the farming population4 #ahd ,see above1 pp4 #cac to #cae1 chapter #ah4 ,,investigation ,,of ,,causes ,,governing ,,the ,,distribution ,,of ,,native ,,vegetation4 ,it seems singular that such well and widely understood designations and important distinctions should not long ago have been made the subject of careful investigation and precise definition by agricultural investigators4 ,for apart from their practical importance as guides to the purchaser of land1 or settler1 this correlation of land-values and natural vegetation is of the utmost interest in offering an opportunity for researches on the factors which determine the choice of these several trees and the corresponding shrubby and herbaceous growths4 ,moreover1 the cultural results and adaptations corresponding to certain natural growths being known from experience1 a thorough knowledge of the soils so characterized should enable us to project into new lands1 where experience is lacking1 the benefits of experience already had2 even in cases where1 from some cause1 the natural vegetation is different1 or absent4 ,only very fragmentary and casual observations in this line are on record thus far1 almost the only generally recognized chemical characterization of plant habit being that of calciphile 7lime-loving71 and calcifuge 7lime-repelled7 ones1 but with few attempts at more than local application4 ,yet1 to ascertain by the physical and chemical examination of soils what are determining factors of certain natural vegetative preferences1 which are invariably followed by certain agricultural results1 should not be an unsolvable problem1 and its practical importance should justify its most active investigation4 ,investigations in ,mississippi4--,in his explorations connected with the ,geological and ,agricultural ,survey of the ,state of ,mississippi1 as well as1 later on1 in similar researches carried on in other states1 the writer was forcibly struck with the close correspondence of the limits of geological formations with those of vegetative zones2 so much so that he was led to rely very largely on the latter as indicative of the probable occurrence of outcrops that otherwise1 in a level country1 would have passed unperceived4 ,these observations upon the correlations between virgin soils and their native vegetation having originally been made by the writer1 in great detail1 in the state of ,mississippi1 from #ahee to #ahgb1 and that state being from natural causes a peculiarly cogent illustration of such correlation3 it seems advisable to describe first1 somewhat in detail1 the facts observed there1 and subsequently to compare them with what has been observed elsewhere by him or others4 ,no claim is made to an even approximately exhaustive presentation of the whole subject1 even within the ,united ,states2 nor is it intended to give complete lists of vegetation4#ahe ,the object is to give such facts as have been fairly well established by observation1 hoping that more thorough investigations in the same line will thereby be stimulated4 #ahe ,such lists1 so far as the ,state of ,mississippi is concerned1 may be found in the writer's ,report on the ,agriculture and ,geology of ,mississippi1 #ahfj4 ,see also ,plant ,life of ,alabama1 by ,charles ,mohr4 ,,vegetative ,,belts ,,in ,,northern ,,mississippi4 ,the diagram below is a sketch-map of the most northern part of ,mississippi1 showing the narrow parallel belts of successive geological formations or terranes running north and south1 which bear the varying zones of vegetation characteristic of each one1 as indicated in the legend beneath4 ,illustration3 ,,fig4 #gg4--,sketch map of ,soil ,belts in ,northern ,mississippi1 east and west4 ,,soil ,,regions ,,of ,,northern ,,mississippi1 ,,showing ,,changes ,,from ,,east ,,to ,,west1 ,,and ,,lime ,,percentages ,,in ,,soils4 ,lime1 p4c4 ,soil ,character4 ,vegetation4 #a4 4#dj-- 4#fj;,clay loams1 clay4 ,oaks1 sweet gum1 tulip tree1 walnut1 red cedar1 ash1 hickories4 #b4 4#je-- 4#ad,sandy loams1 sands4,short-leaf pine1 post1 scarlet and black-jack oaks1 black gum1 chestnut4 #c4 #a4jj--a4dj8,white lime0 ,red cedar1 crab-apple1 ,chickasaw prairie2 clays and plum1 sturdy post and black-jack clay loams4 oaks1 honey locust4 #d4 4#cj-- 4#ej ,mellow red loams of,oaks1 hickories1 walnut1 tulip 8,pontotoc ridge40 tree1 ash1 cherry1 umbrella tree4 #e4 4#jh-- 4#ah ,heavy gray clay ,scrubby post and black-jack oak1 soils1 some gray short-leaf pine4 sands4 8,flatwoods40 #f4 4#ae-- 4#be,sandy ridges and ,post1 black-jack1 scarlet and uplands1 broken4 upland willow oaks1 small2 some chestnut4 #g4 4#be-- 4#ce ,mellow clay loams ,fine black1 red1 post1 ,spanish of 8,table lands40 and black-jack oaks1 hickories1 sweet gum4 #h4 #b4jj--e4jj;,calcareous sandy ,oaks as above1 tulip tree1 ash1 silt1 8,bluff loess0 honey locust1 linden1 sassafras1 8,cane ,hills40 umbrella tree1 cane4 ---------------------------------------- ------------------------- #i4 4#dj--a4aj ,mississippi ,bottom4,basket1 white and black oaks1 ash1 tulip tree' #i;a4 #a4ab-- ,yazoo backland honey locust1 pecan1 shell-bark buckshot clay4 hickory1 walnut1 hackberry1 cane4 #i;b4 4#dj ,sandy alluvium1 ,sweet gum1 maple1 willow oak1 8,frontland40 elm1 hackberry4 ---------------------------------------- ------------------------- #aj4 4#bf-- 4#dj ,light sandy loam of,dogwood1 sweet gum1 holly1 ash1 8,dogwood ridge40 sassafras1 prickly pear4 ---------------------------------------- ------------------------- ,limestone ,belt4--beginning on the east we have1 first1 a narrow belt of limestones of the carboniferous formation1 on which there is a fine growth of various oaks1 with walnut1 hickory1 sweet gum1 tulip tree and red cedar1 and a very productive soil4 8,pine ,hills40--,next adjoining on the west comes a belt of sandy1 non-calcareous beds of the lower ,cretaceous formation1 about #ah miles wide4 ,it has a hilly surface1 and outside of the narrow valleys1 the prevalent timber is short-leaved pine and scrubby black-jack oak1 with some post oak and small black gum1 and a few large chestnut trees4 8,prairie0 ,belt4--,westward of this belt we descend into a level 8prairie0 region1 six to twelve miles wide2 the 8white lime country10 having heavy black clay soils1 underlaid by the cretaceous 8rotten limestones20 which are profusely productive4 ,the sparse tree growth consists of stout1 vigorous and dense-topped post and black-jack oaks1 with clumps of crab-apple1 ,chickasaw plum thickets1 and an occasional red cedar4 ,pontotoc ,ridge4--,west of the prairie belt we ascend into a ridgy hill country1 twelve to fourteen miles wide2 the 8,pontotoc ridge10 formed of the soft limestones and marls of the upper cretaceous formation1 and covered with a deep red soil1 which bears a rich growth of oaks1 with hickory interspersed1 and black walnut1 umbrella and tulip tree even on the ridges4 ,this is one of the finest agricultural regions of the ,state4 ,flatwoods4--,from the ,pontotoc ridge and its fine lands and timber we descend to westward into the 8,flatwoods0 belt1 three to eight miles wide2 a level country underlaid by heavy gray non-calcareous clays of the tertiary formation1 from which most of its soil is directly formed4 ,it bears a pretty dense growth of the same species of oaks that characterize the prairies farther east1 but the form1 habit and size of the trees is so different that many of the inhabitants believe them to be different species4 ,the black-jack oak looks like small1 dense-topped apple trees2 the post oak1 on the contrary1 has an open top of the form of a short-handled1 spreading broom4 ,the soil is poor and unthrifty1 as are the few disappointed settlers1 who bought the land on the strength of its oak-tree growth4 7,see page #ejj74 ,brown ,loam ,region4 ,table ,lands4--,adjoining the ,flatwoods on the west is a broad upland region1 with a brownish-yellow soil and subsoil1 extending nearly to the edge of the ,mississippi bottom4 ,in its eastern portion it is rather broken and hilly1 with sandy ridge soils1 a mixed growth of oaks and short-leaved pine1 and occasional chestnuts2 a fair farming country only4 ,to westward the ridges become lower and broader1 assuming a plateau character4 ,the pine disappears1 and black1 ,spanish1 red and white oak1 with much hickory1 largely replaces the black jack and post oak2 thus characterizing the fertile brown-loam 8table-lands0 that extend through western ,tennessee and ,mississippi into ,louisiana1 and have long been noted for their high production of fine upland cotton4 ,cane ,hills4--,on the western border of the table-land region1 and here forming a strip only a few miles wide along the edge of the ,mississippi bottom1 but from #gj to #dej feet above it1 lies the remnant of what farther south constitutes a wide and important agricultural belt2 the ,bluff or ,loess formation1 locally known as 8the ,cane ,hills40 ,the soil is largely composed of grains of sand and silt cemented by lime carbonate2 it is therefore calcareous1 and as on the ,pontotoc ridge1 described above1 we find here the black walnut1 the tulip tree1 ash and others1 elsewhere restricted to the alluvial 8bottoms10 on the ridges themselves1 from sixty to a hundred feet above the stream beds4 ,mississippi ,bottom4--,at the western foot of this bluff there lies the great ,mississippi ,bottom1 with its rich soils and varied forest growth4 ,this also1 however1 subdivides into at least three distinct soil and vegetative zones1 viz41 the sandy 8,frontlands10 which lie on the immediate banks of the great river and its main branches1 and the heavy clayey 8,back-land0 areas1 whose soils are partly the product of modern swamp deposits from backwaters1 partly result from the disintegration of strongly calcareous clays constituting the lower part of the ,bluff or ,loess formation4 ,a third natural subdivision is the 8,dogwood ridge10 a narrow belt of slightly elevated land1 mostly above ordinary overflows1 which extends diagonally from the ,mississippi river to the ,yazoo bottom1 and seems to be the continuation of 8,crowleys ridge0 in ,arkansas4 ,each of these soil belts has its own characteristic forest growth1 as indicated in the table below the map4 ,we have here along an east-and-west line of about #bjj miles1 eleven markedly distinct zones of vegetation1 readily recognized as such by every farmer1 and each underlaid by a distinct geological terrane4 ,it does seem as though a close study of these and of the soils overlying them should lead to some definite results showing the physico-chemical causes of these differences4 ,lime apparently a governing ,factor4--,the connection of some of these changes in vegetation with the calcareous nature of the corresponding formation has already been referred to4 ,as regards four of the eleven divisions1 this is obvious even to the casual observer1 and is well known to the population1 who speak of the 8lime country0 or belts being1 as a matter of common knowledge1 the best land2 in full accord with what1 in ,kentucky and elsewhere1 has passed into a popular maxim4#ahf #ahf 8,a lime country is a rich country40 ,taking as a guide the trees and plants which characterize the obviously calcareous lands1 our next step should be to verify1 if possible1 the fact that wherever these occur naturally1 lime is abundant in the soil in comparison with those lands in which such vegetation does not occur naturally1 or perhaps even fails to flourish when planted without special fertilization4 ,this the writer has sought to do1 first in connection with the survey work of the state of ,mississippi1 and subsequently in the wider field that has since come under his observation4 ,,soil ,,belts ,,in ,,southern ,,mississippi4 ,in ,mississippi1 the general conclusions derived from the observations made on the northern cross section1 are corroborated many times over in other portions of the state4 ,aside from the cretaceous prairie region1 there runs across the middle of the state a belt of varying width1 of calcareous tertiary beds1 which also give rise to more or less extensive tracts of 8black prairie0 lands1 interspersed with non-calcareous1 mostly sandy ridges1 the lower slopes of which1 influenced by the calcareous beds1 bear an oak and hickory growth1 while the higher portions have only pine1 and usually remain uncultivated4 ,southward of this 8central prairie0 belt lies the long-leaf-pine forest area of the state1 underlaid throughout by sandy1 non-calcareous formations1 with poor sandy soils1 save here and there in patches1 which can be at once recognized by the replacement of the long-leaved pine by a vigorous oak growth2 as is also the case where the pine area abuts against the calcareous 8,cane ,hills0 on the west4 ,the bottom soils of this region are largely 8sour10 and bear the gallberry 7,prinos glaber71 bay galls 7,persea ,carolina71 ti-ti 7,cliftonia monophylla71 candleberry 7,myrica cerifera71 various whortle-berries1 the pitcher plants 7,sarracenia71 yellow star grass 7,aletris71 sundews1 ,xyris1 ,eriocaulon1 and other plants of similar habits4 ,vegetative and ,soil ,features of the ,mississippi ,coast ,belt4--,south of the long-leaf pine area lie the coast flats1 with sour1 sandy soils underlaid by stiff clays4 ,on these 8pine meadows0 of the ,mississippi coast occur some of the most striking cases of modifications of vegetation due to physical and chemical causes4 ,as is well known1 the long-leaved pine habitually belongs to the dry sandy uplands of the ,gulf ,states2 the deciduous cypress1 on the other hand1 is most characteristic of the swamps1 where its roots are permanently submerged in water4 ,but on the pine meadows of the ,mississippi coast we see these two incongruous trees growing side by side1 though sadly worsted by their mutual concessions2 their heights usually ranging from #ab to #ae1 rarely as much as #ah feet4#ahg ,yet both preserve their characteristic forms1 the cypress being an exact miniature reproduction of the usual level-topped swamp form1 except as to the 8knee0 feature2 while the pine differs only in stature from its giant brethren of the pine hills1 from which it can be traced down through all grades of transition4 ,the soil on which this growth occurs is a sour1 sandy one1 one and a half to three feet in depth1 underlaid by a solid1 impervious gray clay1 above which is usually found several inches of coffee-colored bottom water1 which drains slowly into the sluggish water-courses1 themselves carrying brownish1 sour1 but very clear waters4 ,analysis shows the soil to be sour and extremely poor1 especially in its lime and phosphates 7see chapter #ai1 p4 #ceb72 its herbaceous vegetation consists exclusively of very small-seeded1 8calcifuge0 plants 7sedges1 orchids1 ,juncus1 ,hmodorace1 ,xyris1 ,polygala1 etc474 ,this land is wholly unproductive and affords but indifferent pasturage1 except the first season after burning-over2 probably because of the effect of the minute amount of ashes so added4 ,as the coast is approached1 the clay subsoil has an increasing depth of sandy soil-mass above it1 and on these 8sand hammocks0 the long-leaved pine gradually assumes more and more of its usual stature2 the cypress disappears1 and the ,cuban pine 7here called pitch pine7 gradually comes in2 while the sedgy vegetation diminishes and finally disappears4 ,on this land crops may be grown as in the long-leaf-pine uplands4 #ahg ,r4 ,m4 ,harper1 who has graphically described the vegetative features of the coastal plain of ,georgia 7,contr4 from the ,dep4 of ,bot4 ,colum4 ,univ4 ,nos4 #aib1 #bae1 #baf1 #aijb-je2 also ,bull4 ,torr4 ,bot4 ,club #bi-cb71 claims the deciduous cypress of the wet pine-barrens and ponds therein1 the vegetation of which greatly resembles that of the pine meadows of the ,mississippi sea-coast1 to be a distinct species1 ,taxodium imbricarium1 the leaves of which are imbricated1 instead of two-ranked and with spreading leaflets4 ,he supports this distinction mainly by the differences in habit from the ,louisiana swamp cypress1 and the fact that the imbricated form occurs wholly on non-calcareous land1 while the other is at home in the calcareous alluvial areas4 ,the imbricated form has been observed and commented on before1 as a mere ecological variation1 and in the writer's opinion this is all that can be claimed1 in view of the much greater differences in the form of other trees1 notably oaks1 illustrated below1 caused also by lime4 ,there would1 fortiori1 be reason for claiming at least three different species of post oak and black-jack 7and two of willow oak71 which differ not only in tree form but also in the form and number of leaf lobes1 and yet can be traced into one another by innumerable transition forms4 ,if new species are to be established on such grounds1 it is hard to see where the variations manifestly due to environment are to come in4 ,but on the immediate coast1 evidently under the influence of the aboriginal 8shell mounds10 the yellow sandy soil becomes blackish from the 7humus-forming7 effect of the lime thus supplied2 and concurrently the coast live-oak 7,q4 virens71 grape vines1 the ,hercules club 7,aralia spinosa71 8l'herbe a trois quarts0 7,verbesina sp471 and numerous leguminous plants 7which are wholly absent from the pine meadows7 take possession of the land1 which is very productive and has been specially utilized in the growing of ,sea ,island cotton4 ,here the clay stratum is #ae to #bj feet below the surface1 and roots penetrate to great depths in the pervious soil1 whose great thickness makes up for its low percentage of plant-food 7see table below74 ,this land is distinctly limited by the extent of the shell heaps1 past or present1 and shows a respectable percentage of lime4 ,illustration3 ,,fig4 #gh4--,schematic profile of the ,mississippi ,coast ,belt1 through ,jackson ,county4 ,the annexed schematic profile 7fig4 #gh7 illustrates these changes of soil and vegetation1 which furnish a striking example of the effective modification of vegetative features by physical and chemical soil-conditions4 ,it would be difficult to find a more striking exemplification of the effect of lime carbonate1 not only upon the vegetation but also upon the physical and chemical characters of the hopelessly unproductive soil of the sand hammocks and pine meadows2 no longer brown and sour1 but jet black and neutral1 modifying favorably every physical quality4 ,humus likewise nowhere shows its benefits more strikingly4 ,table of ,lime-,percentages4--,the table below shows the average lime percentages observed in most of the several vegetative areas mentioned above4 ,to meet the objection sometimes made that the vegetative changes noted may be due to the larger amounts of phosphoric acid and potash frequently found in calcareous lands1 the percentages of the latter are also given4 ,considering the origin of limestones1 such a connection is not unexpected1 but it is far from constant4 ,on the contrary1 the frequent co-occurrence of much lime and high production with small percentages of phosphoric acid and potash leads to the conclusion1 already discussed 7see chapter #ai1 p4 #cfe71 that in presence of abundance of calcic carbonate1 smaller percentages of phosphoric acid may be considered adequate than when lime is deficient1 on account of greater availability4 ,almost the same may be said of potash2 and it is quite possible that the presence of large amounts of lime tends to prevent the leaching-out of this base1 in consequence of greater facility for the formation of zeolites4 ,illustrations of this kind have already been given 7chapters #c1 #bb74 ,definition of 8,calcareous ,soils40--,it will be noted that the very obvious and important changes of vegetation are brought about by comparatively slight differences in lime-content4 ,in fact1 only two of the soils enumerated above would1 according to the estimates usually given in books on soil composition1 be considered as properly calcareous4 ,but the decisive feature in this matter must evidently be the native vegetation1 which expresses the nature of the land much more clearly and authoritatively than any arbitrary definition or nomenclature can possibly claim to do4 ,a soil must be considered as being calcareous whenever it naturally supports the vegetation characteristic of calcareous soils4 ,,table ,,showing ,,native ,,forest ,,growth1 ,,popular ,,estimate ,,of ,,durability ,,and ,,initial ,,production1 ,,and ,,percentages ,,of ,,lime1 ,,phosphoric ,,acid ,,and ,,potash1 ,,in ,,mississippi ,,lands4 ,no4 ,name4 ,natural ,vegetation4 ,production ,per ,acre4 ---------------------------------------- ------------------------ ,black ,mainly sturdy black-jack and#djj lbs4 cotton lint1 #agb ,prairie post oak1 red cedar1 crab decreasing to #bjj lbs4 ,soil4 apple and honey locust4 in #cj years4 ---------------------------------------- ------------------------ ,pale ,scarlet1 post and ,spanish #bjj lbs4 cotton first #afd ,yellow oak1 small4 year1 tailing off ,ridge to #ge to #ajj lbs4 ,loam4 by #eth year4 ---------------------------------------- ------------------------ ,pontotoc ,oak1 hickory1 walnut1 sweet #cej-djj lbs4 cotton #bbf ,ridge and black gum1 honey locust4 lint1 #cjj lbs4 after ,soil4 #bj years4 ---------------------------------------- ------------------------ ,heavy ,post and black-jack oak1 #bj bushels of corn #bcj ,flatwood and some short-leaved pine4 first year--then ,soil4 nubbins only4 ---------------------------------------- ------------------------ ,black-,jack,black-jack oak1 pine1 ,unproductive4 #cde ,ridge huckleberry4 ,soil4 ---------------------------------------- ------------------------ ,oak and ,red and post oak1 pig-nut #bjj lbs4 cotton lint ,pine hickory1 short-leaved pine4 at first2 #ajj lbs4 #adb ,upland #f-h years4 ,loam4 ---------------------------------------- ------------------------ ,brown ,black1 post1 ,spanish and #djj lbs4 cotton--#bej #bai,table-land black-jack oak1 hickory1 lbs4 after #bj years4 soil4 sweet and black gum4 ---------------------------------------- ------------------------ ,bluff or ,cane1 black and white oak1 #djj lbs4 cotton1 #bcg ,loess tulip tree1 linden1 decreasing to #bej lbs4 ,soil4 sassafras4 after #cj years4 ---------------------------------------- ------------------------ 8,buckshot0,hickory1 ash1 sweet gum1 #hjj lbs4 cotton lint1 #cij ,soil4 pecan1 cow oak1 honey reduced to #ejj lbs4 locust1 cane1 crab-apple1 in #cj years plum4 cultivation4 ---------------------------------------- ------------------------ ,pine ,long-leaved pine1 with #bj-cj bushels corn for #bjf ,hill scarlet and post oak1 one year--then ,soil4 scattered small and nubbins4 ,usually occasional pig-nut good sweet potatoes hickory4 for #b-c years4 ---------------------------------------- ------------------------ ,pine ,dwarf long-leaved pine1 ,unproductive4 ,bears #bae ,meadow cypress1 sedges1 orchids1 small-seeded 8sour0 ,soil4 ,hmodorac1 etc4 vegetation4 ---------------------------------------- ------------------------ ,shell ,live and water oak1 cedar1 #cjj lbs4 sea-island #hh ,hammock magnolia1 holly1 dogwood1 cotton for #ae years4 ,soil4 sweet gum1 hickory1 sassafras1 grape1 ,hercules club1 etc4 ---------------------------------------- ------------------------ ,no4 ,name4 ,physical ,k,o4 ,ca,o4 ,mg,o4 ,p,o4 ,humus4 ,character4 ---------------------------------------- ------------------ ,black ,heavy adhesive #agb ,prairie dark-colored 4#ccc #a4cfg 4#cfc 4#ajd #a4be ,soil4 clay4 ---------------------------------------- ------------------ ,pale ,pale yellow #afd ,yellow sandy loam4 4#jic 4#jfi 4#abf 4#jcc 4#ej ,ridge ,loam4 ---------------------------------------- ------------------ ,pontotoc 8,mulatto0 #bbf ,ridge medium loam4 4#cgd 4#bha 4#bcd 4#jhb #a4jj ,soil4 ---------------------------------------- ------------------ ,heavy ,heavy gray 4#gec 4#agh 4#hca 4#jeb 4#cje #bcj ,flatwood clay4 ,soil4 ---------------------------------------- ------------------ ,black-,jack ,very sandy #cde ,ridge loam4 4#jgc 4#adb 4#ajj,trace4 4#bj ,soil4 ---------------------------------------- ------------------ ,oak and ,medium ,pine loam4 #adb ,upland 4#bcf 4#jib 4#aif 4#jia 4#ej ,loam4 ---------------------------------------- ------------------ ,brown #bai,table-land ,clay loam4 4#fcj 4#bgj 4#dej 4#baj 4#gi soil4 ---------------------------------------- ------------------ ,bluff or ,sandy loam4 4#eaa #e4ibac4bgh 4#adc 4#gb #bcg ,loess ,soil4 ---------------------------------------- ------------------ 8,buckshot0 ,heavy #cij ,soil4 calcareous #a4ajd #a4cdia4ffe 4#cjd #a4j clay soil4 ---------------------------------------- ------------------ ,pine ,light sandy #bjf ,hill loam2 mere 4#bei 4#abi 4#ahj 4#jcj 4#ce ,soil4 sand at #c feet4 ---------------------------------------- ------------------ ,pine ,very sandy #bae ,meadow loam1 gray 4#jfa 4#jbc 4#jfi 4#jba ,soil4 clay subsoil4 ---------------------------------------- ------------------ ,shell ,very sandy #hh ,hammock loam1 deep4 4#jhj 4#aae 4#jfe 4#ajg 4#ge ,soil4 ---------------------------------------- ------------------ ,starred values 77 are approximate4 ,,differences ,,in ,,the ,,form ,,and ,,development ,,of ,,trees4#ahh ,it will be noted that in the above table1 as well as in the discussion preceding it1 identical species of trees are ascribed to vegetative areas of widely different productive capacity4 ,perhaps the most striking example is that the cretaceous prairies and the adjoining flatwoods belt1 standing respectively highest and lowest in the scale of productiveness1 are yet bearing specifically identical tree-growth1 to-wit1 the post oak 7,quercus minor7 and the black-jack oak 7,q4 marylandica74 ,while to the field botanist#ahi there can be no question as to the absolute specific identity of the two trees as growing on the respective areas1 yet the mode of development of both is so different in the two cases1 that1 as before remarked they are popularly supposed to be different 8kinds40 #ahh ,it is a matter of regret to the writer that owing to the long distance intervening and the difficulty of securing competent and sympathetic observers for such work1 it has not been possible for him to secure photographs of the tree-forms here discussed4 ,at the time his own observations were made1 photography was practically unavailable as yet1 and the figures given are therefore based upon sketches made at the time1 and partly upon recollection4 ,they represent types rather than definite individuals1 which were however described when fresh in mind1 in the ,report on the ,agriculture and ,geology of ,mississippi1 #ahfj1 pages #bed et seq4 #ahi ,it has been already1 and doubtless will be again and increasingly1 attempted to make distinct 8species0 of these widely different forms of trees4 ,but this is simply begging the question4 ,mere external diagnostic marks will not avail here2 it would have to be shown that the seed of these different forms do not produce the other forms under changed conditions4 ,until this has been done1 the number-less transition forms which he that runs may observe in the field1 throw upon the species-makers the onus of proof of differences of specific value--if it be possible to define such value4 ,forms of the ,post ,oak4--,the post oak of the prairie lands is a tree #ej to #gj feet high1 with a stout1 excurrent1 rather conical trunk1 often somewhat curved to one side above1 and densely clothed from within #ab or #ae feet of the ground with comparatively short1 sturdy branches set squarely to the trunk1 much crooked 7geniculate71 often reflexed downward2 altogether forming a dense head1 beneath whose thick foliage1 a bird or squirrel is quite secure from the hunter's aim4--,in the flatwoods1 on the contrary1 the post oak has a thin1 rather short trunk1 divided up at #ae or #bj feet height into long1 rod-like branches1 spreading broom-fashion1 and scantily clothed with short twigs bearing tufts of leaves2 thus forming an open head1 in which no creature can hide effectually4 ,on the brown-loam table-lands1 again1 the post oak has a straight1 rather slender1 excurrent trunk with long and more or less crooked limbs projecting at a large angle1 sometimes even drooping1 and freely divided up into lateral1 leafy branches2 the trees attain from #dj to #ee feet in height4 ,again1 on the high sandy ridges which are interspersed in the eastern portion of the brown loam area1 we find1 generally associated with a similarly depauperated form of the black-jack oak1 and with the ,upland ,willow oak 7,q4 cinerea71 a form of the post oak intermediate between that of the ,flatwoods and the ,table lands2 twelve to fifteen feet high1 with thin trunk1 8sprangling0 long1 crooked branches1 clothed with sparse tufts of leaves4 ,these four strikingly distinct types are shown schematically1 in their extreme development1 in the subjoined figures4 ,it is hardly necessary to say that between these extreme forms there are many degrees of transition1 corresponding to the transitions between the several soil-classes respectively represented by them2 or they may be developed into depauperated types4 ,thus1 for example1 the forms of the post and black-jack oak found on the sandy ridges of the yellow loam region1 hardly need experience in the observer to interpret them as characterizing a wretchedly poor soil4 ,forms of the ,black-jack ,oak4--,not less striking are the characteristics of the forms of the black-jack oak as developed upon these several kinds of land4 ,the black-jack of the prairies is a low tree with a dense rounded head1 often somewhat flattened above1 and a low1 thick-set trunk divided up into square-set branches1 so densely clad with foliage that no light penetrates into the interior1 and birds can safely hide and nest within it4 ,the height rarely exceeds #ce feet1 the head being #bj to #cj feet across4 ,the ,flatwoods form1 on the contrary1 rarely exceeds #ae feet in height1 with a very rough bark and a small1 rather dense1 rounded top1 giving the whole the appearance of a small apple tree4 ,practically the same form is seen on poor1 clay ridges of 8hog-wallow0 land4 ,illustration3 ,loam ,upland4 ,illustration3 ,sandy ,ridges4 ,illustration3 ,flatwoods4 ,illustration3 ,black ,prairie4 ,,fig4 #gi4--;,extreme ,forms of ,post ,oak 7,quercus minor ,marsh41 obtusiloba ,mich474 ,on the brown-loam lands the black-jack1 like the post oak1 has a rather slender1 often somewhat crooked1 but excurrent trunk #ce to #ej feet high1 with more or less crooked limbs of moderate length1 well provided with leafy branches1 but forming altogether a rather open crown4 ,a depauperated form of this type occurs on the sandy ridges of the yellow-loam region and is #ab to #ae feet high1 with slender1 crooked branches1 clothed with scanty foliage2 as shown in ,figure ,no4 #hj1 alongside of the other typical forms4 ,illustration3 ,loam ,upland4 ,illustration3 ,flatwoods4 ,illustration3 ,sandy ,ridges4 ,illustration3 ,black ,prairie4 ,,fig4 #hj4--;,extreme ,forms of ,black-,jack ,oak 7,q4 marylandica ,mursh1 nigra ,wangh74 ,in all these variations of the tree forms1 there is also a concomitant variation in the forms and other characters of the leaves4 ,thus in the compact forms of the black-jack oak1 the trilobate leaf is almost completely obliterated1 the leaf being simply rounded-cuneate1 somewhat auriculate at base4 ,in the sparse-branched upland forms the leaves are deeply three-lobed1 and the ferruginous tomentum of the lower surface is much less pronounced4 ,the lobation of the post oak also varies considerably both in the numbers of lobes and in their obtuseness4 ,similar differences prevail in the case of the black and ,spanish oaks2 thus in the latter1 the long terminal1 falcate lobe is always most pronounced on 8rich0 soils1 while on poor ones the trilobate leaf predominates4 ,of course all these forms may be found bearing acorns1 so that they undoubtedly represent adult trees4 ,characteristic ,forms of other ,oaks4--,similar general features are repeated in the case of the other species of oaks1 and also more or less in other kinds of trees2 though mostly less pronouncedly than with the two species above described4 ,among the more striking are the two forms of the willow oak 7,q4 phellos71 which on low1 undrained ground assumes the low1 rounded1 8apple-tree0 form1 while on well-drained uplands of good fertility it is a beautiful1 slender tree producing almost the effect of the acacia type2 it is then a sign of first-class land4 ,the scarlet oak rather reverses these types2 on good1 8brown-loam0 upland it is of rounded form1 not very tall1 with sturdy1 rough-barked trunk2 while on poor hillside lands its tall1 smooth1 white trunk stands out as a conspicuous admonition to the land-seeker to beware of a poor purchase4 ,the black and ,spanish oaks also indicate1 by tall thin trunks1 a deterioration of the land as compared with the lower and more sturdy growth on areas relatively richer in lime4 ,sturdy ,growth on ,calcareous ,lands4--,one feature invariably repeated1 not only in ,mississippi but throughout the ,united ,states1 is that in many strongly calcareous soils the growth of all trees1 as well as of shrubs and of many herbaceous plants1 is of a more sturdy and thick-set habit than that of the same species grown on thin1 sandy1 or generally on non-calcareous land4 ,this effect is quite as apparent in the arid region of the ,pacific ,coast as in the ,atlantic ,states1 on the prairies of the ,middle ,west1 and of the ,gulf ,coast4 ,the experienced farmer recognizes this habit of the tree-growth as a sign of good land1 and the reverse1 viz41 trees of lank1 tall and thin growth1 as evidence to the contrary1 from the ,atlantic to the ,pacific4 ,cotton ,plant4--,the cotton plant affords very striking evidences of this influence of lime4 ,on the bottom lands of a creek in ,rankin county1 ,mississippi1 the writer found a 8patch0 of cotton with luxuriant stalks reaching above the head of a man on horseback1 but almost devoid of 8squares0 or blooms4 ,the soil was very dark and rich-looking1 but was derived from a non-calcareous tertiary terrane surrounding the heads of the stream4 ,a few rods below1 the latter crosses the line of a calcareous terrane1 from which copious marly debris have been washed down on the bottom soil4 ,here the cotton was just half as high as above1 and thickly covered with squares1 blooms1 and bolls4 ,another similar example was noted on the ,chickasawhay river1 in ,wayne county1 ,miss4 ,where that stream flows through the non-calcareous1 lignitiferous area of the tertiary formation1 its bottom lands bear cotton crops of medium productiveness only1 the stalks being of the usual height of about three feet1 and only fairly bolled4 ,but a short distance below the point where the soft marls of the marine tertiary are cut into by the stream1 the cotton plants on the bottom lands are from #ah to #bj inches high only1 closely branched1 and literally thronged with cotton bolls1 so that the fields appear a solid mass of white4 ,the only objection urged against this land is that to pick such cotton 8breaks the backs0 of the pickers4 ,the tree growth of the bottom1 of course shows a corresponding change4 ,lime ,favors ,fruiting4--,in connection with the obvious changes of form and stature caused by the presence of an abundant supply of lime carbonate in soils1 there is another that has been long noted in cultivation1 but is no less striking in the native vegetation4 ,the abundant fruiting of oaks on such lands as compared with the same species on non-calcareous soils is a matter of common note in the ,mississippi ,valley states2 and the same is true of other trees1 and of herbaceous plants as well4 ,the fruit on the lime soils is often smaller1 unless much humus is present2 but the statement made in ,europe that cultivated fruits1 and especially grapes1 are sweeter on calcareous lands1 is abundantly verified in the native fruits of the ,mississippi ,valley states as well2 where the various wild berries1 haws1 plums1 etc41 are well known to the younger part of the population to be much sweeter and higher-flavored in certain 7calcareous7 localities than in others1 besides being usually more abundant4 ,this is entirely in accord with the well-known fact that the application of lime checks the excessive wood and leaf growth resulting from excess of nitrogen as well as moisture2 while on the other hand1 the injurious effects of overdressing with lime or marl are known to be repressed by the use of stable manure1 or by green-manuring4 ,the repression of excessive wood growth by lime would seem to offer a simple explanation of the compact habit of growth on calcareous lands2 and the extraordinary sweetness of fruits grown in the arid region as compared with the same in the humid1 is fully in accord with the high lime-content of the arid lands4 ,stunted ,growth4--,in practice it will be found in most cases that a stunted native growth is due not so much to lack of plant-food in the soil1 as to unfavorable physical conditions4 ,among these1 shallowness1 and extreme heaviness of the soil are the most common causes4 ,the 8scab lands10 underlaid by impervious rock at a depth too slight for culture plants1 as in many plateaus of the ,pacific ,northwest1 and in rocky or mountainous regions generally1 are cases in point4 ,strata of impervious clay often produce the same result2 but in this case1 should such clay be intrinsically capable of supporting plant growth1 the land can often be made available for orchard purposes by blasting with dynamite 7see chapter #aj1 p4 #aha74 ,the post oak 7and black-jack7 flats of the ,mississippi ,valley states are familiar examples of land whose dwarfed tree growth causes it to be avoided by settlers2 similarly1 a dwarfed growth of red elm 7,ulmus rubra71 hackberry and ash indicates in the flood plain of the ,red river of ,louisiana a heavy 8waxy0 red clay1 or 8gumbo0 land1 scarcely available for agricultural purposes4#aij ,the gray or white 8cray-fishy0 bottom and bench lands of the ,southwestern ,states1 so poor in lime1 phosphates and humus as to be worthless under existing conditions1 are characterized by an easily recognized scrubby growth of ,water and ,willow ,oaks 7,q4 nigra1 or aquatica1 and phellos71 with low1 rounded tops2 while the same trees1 when well developed1 indicate highly productive lands4 #aij ,rep4 of ,geological ,reconnaissance of ,louisiana2 ,new ,orleans1 #ahgc1 p4 #bg4 ,physical vs4 ,chemical ,causes of ,vegetative ,features4--,the extent to which the modifications of form alluded to above are referable to chemical and physical causes respectively1 can be approached by the discussion of the presence or absence of certain trees from soils of extreme physical character1 but otherwise normally constituted4 ,as has been shown above1 the black-jack and post oaks belong1 as species1 equally to the heaviest and lightest soils within the state of ,mississippi2 to the black and yellow 8prairie0 soils1 as well as to the sandy ridges of the yellow-loam region2 showing for these two species as such1 an independence of physical conditions and an extraordinary adaptability1 found in few other trees4 ,they are frequently found either alone or associated with only a few other species of local adaptation1 such as1 in the prairie lands1 the crab-apple1 wild plum1 and the juniper or red cedar4 ,on the soils of intermediate or loam character1 on the contrary1 they are always associated with other oaks as well as with hickory1 and in that association attain what may be considered their normal type or form4 ,from the fact that the dense1 rounded top is formed by the black-jack oak both on the rich prairie lands and on the poor soils of the ,flatwoods1 it would seem that that form is the outcome of a physical cause1 viz41 the extreme 8heavy-clay0 character of both kinds of land2 and we may note that exactly the reverse effect is observed in the form growing on the poor sandy ridges1 as shown in fig's #gi and #hj4 ,yet it will also be noted that in the case of the post oak1 the poor1 heavy-clay soil of the ,flatwoods produces an open1 broom-shaped top1 while the form assumed on the sandy ridges is substantially the same for both species4 ,care must therefore be exercised in drawing general conclusions as to the effects produced by either physical or chemical causes1 alone1 upon tree forms4 ,lowland ,tree ,growth4--,the variations occurring in the valleys or alluvial bottoms are less obvious to superficial observation1 yet equally important and cogent to the close observer4 ,in the properly alluvial lands1 one dominant condition1 that of adequate moisture supply1 is almost always fulfilled1 irrespective of soil quality4 ,in addition to this1 as stated in chapter #b 7see page #bd71 practically all the alluvial lands of the humid region may be considered as being of a more or less calcareous character1 as compared with the adjacent uplands4 ,these two important conditions dominate in a great measure the minor ones of variation in soil-texture4 ,yet where1 as is largely the case in the southern part of the ,state of ,mississippi1 the amount of calcic carbonate is insufficient to overcome the sourness of the soil1 the vegetative contrasts become extremely striking and characteristic1 as explained above4 ,contrast ,between 8,first0 and 8,second0 ,bottoms4--,a very striking phase of transition between the alluvial bottoms and the uplands proper in the ,cotton ,states are the second bottoms or hammocks of the streams1 whose soil and tree-growth in most cases differ markedly from those of the first bottom2 and these being usually closely adjacent1 often afford a very striking contrast to the latter4 ,from some antecedent geological cause not fully understood1 these hammocks1 usually elevated from #d to #aj feet above the present flood plain1 have almost throughout soils of a fine sandy1 pulverulent or silty nature1 frequently in strong contrast to heavy clay soils in the first bottom4 ,they seem1 moreover1 to have been at some time subject to prolonged maceration under water1 resulting in the reduction of the ferric oxid1 and its accumulation in the lower portion of the deposit in the form of bog-ore spots or 8black gravel40 ,since such a process always results in the abstraction of phosphoric acid from the general mass of the soil1 to be accumulated in the bog ore in an inert condition1#aia these hammock soils1 usually whitish or gray in color1 are almost throughout poor in phosphates as well as in lime2 the latter having been definitively leached out4 ,the resulting vegetation1 as may be imagined1 is widely different from that of the bottom proper1 as well as1 frequently1 from that of the adjacent uplands2 and though level and fair to see1 these hammocks are usually unthrifty and last but a short time under exhaustive cultivation4 ,accordingly1 their forest growth is prevalently that of the poorer class of uplands1 viz41 small-sized post and black-jack oaks1 and in the low ground depauperated water oak1 or less commonly willow oak1 of the low1 stunted type indicative of a soil of inferior productiveness4 ,the luxuriant growth of the present alluvial bottom is often seen within a few feet of the unthrifty vegetation of these hammocks4 ,it is usually only in the limestone regions1 and in the lower course of the larger streams1 that the hammocks or second bottoms are found to be of good fertility4 #aia ,see ,chapter #b1 p4 #bd4 ,the ,tree ,growth of the ,first ,bottoms4 ,the ,cypress4--,among the trees occupying the low ground of the first bottom in the southern ,mississippi states1 the deciduous cypress 7,taxodium distichum7 deserves special mention as an example of extreme variation in form4 ,in sloughs and swampy tracts1 as is well known1 the cypress grows with roots submerged throughout the season1 excepting only the excrescences known as 8knees10 which project above the water1 probably performing some function in connection with the aeration of the root1 which is essential to the root functions in all plants4 ,the trunk rising from the water is supported by numerous projecting buttresses for from #h to #ae feet above the water2 higher up it becomes cylindrical for a height of from #dj to #gj feet1 then divides up into a few widely spreading1 thick1 almost conical branches1 whose twigs and foliage form an almost level surface to the head4 ,this level-topped forest growth characterizes at once the submerged areas of the river and coast swamps4 ,but the cypress is by no means confined to the swamps and sloughs2 it is also found occupying the better class of hammock lands1 #ab or #ae feet above water level4 ,in this case1 however1 the tree assumes a shape and growth so wholly different from that described above as to lead to a popular assertion of a difference of species4 ,as a matter of fact1 however1 the cones of these upland cypresses1 when dropping into the water below them1 reproduce exactly the common swamp form4 ,the extraordinary difference in the aspect of the tree under these different conditions is best seen in the subjoined diagram1 showing the upland cypress to assume the form of the tall willow oak1 with which it is sometimes locally associated4 ,illustration3 ,swamp4 ,illustration3 ,upland4 ,,fig4 #ha4--;,forms of ,deciduous ,cypress on overflowed and on bench-land4 ,the trees from which the annexed sketch is taken grew within thirty feet of each other1 on ,yellow creek1 a small tributary of the ,tennessee river1 in ,tishomingo county1 ,miss4 ,the soil stratum is underlaid by a shaly limestone1 and bears lime vegetation4 ,the fact that the deciduous cypress grows without difficulty on the moister class of lowlands in ,california1 #ab or #ae feet above bottom water1 is of interest in this connection4 ,it then assumes the upland form shown in the figure above1 although not growing quite as tall4 ,the calcareous nature of these soils is probably an important factor in this apparently incongruous adaptation of a subtropical swamp tree to arid conditions4 ,in its swamp form the cypress usually grows in rather shallow1 heavy clay soil1 into the dense subsoil of which the roots penetrate but little4 ,other ,lowland ,trees4--,the lowland hickories1 like their brethren on the highlands1 seem on the whole to prefer the lighter or loamy bottom soils to those of a heavier character4 ,this is especially true of the ,pecan4 ,the latter1 as well as the shell-bark hickory1 is especially indicative of the highest class of bottom soils4 ,the black walnut1 while apparently also best suited in loamy soils1 is also more or less found on heavy bottom lands1 provided they are sufficiently calcareous2 and the same is measurably true of the tulip or white-wood tree4 ,the most frequent occupants of heavy bottom lands1 however1 are the black gum and sweet gum1 so that 8gum swamps0 are usually found to be of that character4#aib ,but in the prairie region1 where the bottom soils are very calcareous and heavy1 as well as in corresponding soils of the 8buckshot0 lands of the great ,mississippi ,bottom1 the chestnut-white 7cow- or basket-7 oak sometimes occupies such ground almost exclusively4 ,among the accompanying trees are especially the honey locust1 the crab-apple1 mulberry and sweet gum1 as well as ash4 #aib ,hence perhaps the vernacular name 8gumbo0 for heavy1 adhesive clay soils in the north central states2 which may also1 however1 be derived from a comparison with the 8gummy0 pods of the cultivated okra or gumbo plant4 ,general ,forecasts of ,soil ,quality in ,forest ,lands4--,while the oaks and pines mentioned as forming the bulk of the timber constitute in the cotton states the prim faci evidence1 as it were1 of the general character of the land1 there are numerous other trees and plants which serve the discriminating land-seeker as a guide for the quality of the soils in different localities4 ,while everywhere1 well-developed black1 red1 ,spanish and white oaks are considered as signs of a high quality of land1 the tall1 thin scarlet1 the upland willow1 and the barrens scrub oak are considered as indications detracting materially from the producing value wherever they prevail4 ,the various hickories are throughout considered as indicating good land when mixed with the oaks1 or by themselves2 while the presence of walnut1 linden and tulip tree will usually raise the estimate of uplands to the highest class4 ,on the other hand1 the occurrence of small black-gum trees and short-leaved pine1 with low huckleberry1 among the oaks of whatever kind1 accompanied as they usually are by the disappearance of the black1 white and ,spanish oaks1 will materially depress the land-values4 ,the appearance of well-formed oaks1 as well as of hickory1 is therefore at once welcomed as an evidence of soil improvement1 while that of low huckleberry bushes and small black gums indicates the reverse4 ,an increase in the thickness and retentiveness of the soil stratum is also usually indicated by the occurrence of short-leaved pine in the long-leaf-pine areas4 ,the black1 red1 white1 and ,spanish oaks belong altogether to soils of medium physical constitution1 only their size upon such lands depending upon the relative richness in plant-food2 but without such changes producing any notable variation in their form4 ,clearly then1 these species are intolerant of extreme physical conditions1 and are practically restricted to soils of 8loamy0 character and easy cultivation4 ,,chapter ,,xxv4 ,,recognition ,,of ,,the ,,character ,,of ,,soils ,,from ,,their ,,native ,,vegetation4 ,,united ,,states ,,at ,,large4 ,,europe4 ,the application of the above data outside of ,mississippi can mostly be verified only in a fragmentary way from such data as are casually given in the reports of ,state ,surveys1 as well as from such observations as the writer has been able to make personally elsewhere4 ,in the latter category the most copious refer to the states of ,alabama1 ,louisiana and ,illinois4 ,,alabama4--,the observations of ,prof4 ,eugene ,a4 ,smith1 and those of ,dr4 ,chas4 ,mohr1 are especially valuable and cogent as to the close correspondence of the soil and vegetative phenomena with those observed in ,mississippi4#aic ,they are faithfully reproduced on the corresponding geological areas1 including also the ,flatwoods4 ,northwest of ,mobile1 on the ,mississippi line1 the long-leaf-pine forest is interspersed with more or less continuous areas bearing a fine oak growth1 with hickories and other trees indicating a calcareous soil4 ,this feature is most extensively developed in ,alabama in what is known as the 8lime-sink region10 on the borders of which the vegetative transition in passing from the non-calcareous sandy pine land1 can be observed in the most striking manner and with frequent alternations4 ,northward of the long-leaf-pine belt1 the tertiary and cretaceous areas show in ,alabama the same features as in ,mississippi1 viz41 black calcareous prairies alternating with ridge lands1 among which in the cretaceous area the ,pontotoc ridge is represented by a series of isolated knobs1 popularly known as ,chunnenugga ridge1 closely resembling the former in its soils and vegetative character4 #aic ,see ,plant ,life of ,alabama1 by ,charles ,mohr1 ,vol4 ,,vi4 ,contr4 ,u4 ,s4 ,nat4 ,herb41 ,u4 ,s4 ,dep't ,agr42 ,alabama ,ed4 of ,same1 ,ala4 ,geol4 ,survey1 #aija4 ,in northern ,alabama1 according to ,dr4 ,smith1 on the various stages of the ,carboniferous formation1 ranging from a sandy or conglomerate character to that of limestones of various degrees of purity1 soils contrast strikingly with each other1 agreeing closely with those seen in the neighboring part of ,mississippi4 ,here1 moreover1 the contrast between the natural vegetative character as well as cultural value of the lands derived from the magnesian limestones 7the 8barrens07 contrasts strikingly with those originating in the purer limestones1 on which the blue grass is at home4 ,,louisiana4--,as to ,louisiana1 whose geological formations correspond closely to those of ,mississippi1 it may be said in general that the vegetative phenomena coincide completely with those observed in ,mississippi4 ,the 8white-lime country0 of northeastern ,mississippi is represented in ,louisiana only by patches occurring here and there on a line laid from ,lake ,bistineau to the coast at ,petite ,anse ,island4 ,but the chief characteristics of the calcareous area1 among them especially that of the occurrence of red cedar and clumps of crab-apple1 persistently reappear4 ,the 8,central ,prairie ,region0 of ,louisiana is quite narrow1 but on it there reappear precisely the same characteristics described in connection with that area in ,mississippi4 ,in the long-leaf-pine region of ,louisiana there occur1 as in ,mississippi1 some isolated patches of a calcareous character1 the largest of which is on the ,bayou ,anacoco in ,vernon ,parish1 near the western border of the ,state4 ,as we emerge from the sandy lands of the long-leaf pine area to that underlaid by the calcareous formation1 we find1 first1 a change to oak and short-leaved pine1 then the oak forest alone2 finally1 on a level black prairie of considerable extent1 the post and black-jack oak in their thick-set form1 clumps of crab-apple1 red haw and honey locust1 here and there a red cedar2 exactly as has already been described in connection with the prairie lands of ,mississippi4 ,to southward of the long-leaf-pine area lies a broad belt of level1 generally treeless1 sandy prairie1 in part dotted with groves of timber1 but otherwise with nearly the same peculiar1 small-seeded herbaceous vegetation observed in the corresponding portion of ,mississippi4 ,but in ,louisiana there intervenes between these gray sour lands and the shell hammocks of the immediate sea-coast with their groves of live-oak1 a belt of black calcareous prairie1 increasing in width and clayeyness towards the ,west1 and acquiring considerable extension in the corresponding portion of ,texas4 ,on these prairies we again find the calciphile vegetation1 including the honey locust1 clumps of crab-apple and red haw1 etc41 but not usually any oak growth1 except 7near the sea-coast7 the live-oak4 ,in the hilly country of northern ,louisiana there is reproduced substantially the vegetative character of the 8short-leaf pine and oak0 uplands of ,mississippi 7see map on p4 #dij1 chapter #bd71 save in that1 owing to the occasional outcropping of the calcareous materials of the ,tertiary1 small prairies with black soil are spotted about here and there4 ,bordering the ,mississippi ,bottom there are a series of oak-upland ridges with a brown loam soil corresponding to the fertile area in northwestern ,mississippi1 with small patches of the 8,cane hills0 loess soils1 bearing a corresponding tree growth4#aid #aid ,see 8,final ,report of a ,geological ,reconnoisssance of ,louisiana10 published by the ,new ,orleans ,academy of ,science in #ahga4 ,in ,western ,tennessee the vegetative zones so distinctly shown in the adjacent portion of ,mississippi are not so strikingly outlined1 but so far as they do exist1 the phenomena observed accord exactly with those heretofore described4 ,the same holds true of ,western ,kentucky1 as is well set forth and graphically described in the reports of the geological surveys of that state by ,dr4 ,david ,dale ,owen1 and later by ,dr4 ,r4 ,h4 ,loughridge4 ,north ,central ,states4--,north of the ,ohio ,river the materials of the geological formations are not nearly as much varied as they are south of the same2 consequently the vegetative features are also much more uniform4 ,it must be remembered that from the ,alleghenies nearly to the ,mississippi1 the states of ,ohio1 ,southern ,michigan1 ,indiana and ,illinois are largely covered by drift deposits overlying the older formations1 except that along the ,ohio and ,mississippi rivers lies the calcareous loam of the ,loess or ,bluff formation4 ,within the states mentioned1 however1 not only are the older underlying formations very generally calcareous1 but calcareous sand and gravel form a large proportion of the drift deposits1 which in most cases overlie the rocks4 ,hence we find from the ,alleghenies to the ,mississippi a predominance of the oak forests which characterizes calcareous soils1 as in the better class of uplands in ,mississippi and ,tennessee2 interrupted only here and there by sandy belts or ridges bearing inferior growth1 among which1 again1 the black-jack and post oaks1 with short-leaved pine1 are conspicuous4 ,but in a large portion of ,illinois1 as well as in ,western ,indiana1 the oak forest is interrupted by more or less continuous belts1 and sometimes by a wide expanse1 of black prairie1 generally treeless or bearing only clumps of crab-apple and haw1 and underlaid more or less directly by the carboniferous limestones1 whose disintegration has materially contributed to the black prairie soils2 which are noted for their high and long-continued productiveness4 ,the lower ground is characterized1 besides clumps of crab-apple and red haw1 by the frequent occurrence of the honey locust1 the lead plant 7,amorpha fruticosa71 the button-bush 7,cephalanthus occidentalis71 and among herbs by the polar plant 7,silphium laciniatum71 the prairie burdock 7,s4 terebinthinaceum71 the swamp rose-mallow 7,hibiscus moscheutos71 the sneezewort 7,helenium autumnale71 the wild indigo 7,baptisia tinctoria and leucophca74 ,the black-jack and post oak are not nearly as frequently found on the prairies of ,illinois as on those of ,mississippi and ,alabama2 but where they occur they assume a similar habit1 including the occurrence of the dwarfed1 apple-tree-shaped form on the low ridges with heavy yellow clay soil1 that sometimes intersect the prairies4 ,the post oak1 moreover1 in a form quite similar to that described as occurring on the ,flatwoods of ,mississippi1 forms the timber of the 8post oak flats0 occasionally found between the low ridges bordering the streams1 or along the edges of the prairies4 ,the herbaceous vegetation of these post oak flats distinctly characterizes them as being poor in lime4 ,in the loamy uplands1 where the calcareous ingredient is more abundant1 the open-headed form of the black-jack and post oak are also found1 interspersed with a luxuriant growth of black1 red and white oak1 with more or less of hickory1 which here assume a magnificent development1 much superior to that seen south of the ,ohio4 ,these yellow-loam uplands correspond very closely in their soil-composition and agricultural character to the brown-loam area of ,mississippi and ,tennessee1 which lies inland from the ,loess belt4 ,where these uplands approach the prairie or the outcrops of a limestone formation1 there is usually added to the oak growth the linden1 the wild cherry and the ash2 the latter two also usually appear in the bottoms of the streams and on the slopes adjacent1 together with the walnut and butternut1 and in the lowest ground the sycamore4 ,the tree growth of the ,loess belt bordering the ,ohio and ,mississippi1 so far as climatic differences permit1 agrees almost precisely with that described in the corresponding portions of ,mississippi and ,tennessee4 ,the change from the oak and hickory growth covering the yellow-loam uplands toward the more calcareous area is evidenced by the appearance of large sturdy trees of sassafras1 together with the linden and sugar maple4 ,descending from the 8bluff0 toward the rich bottom-prairie with its black1 heavy soil1 we at once encounter the familiar indices of the more highly calcareous land1 viz41 the honey locust1 clumps of crab-apple and red haw1 with hackberry1 ,kentucky coffee tree and mulberry on the lower ground4 ,in late summer and during autumn1 a tall growth of the iron weed 7,vernonia71 several ,eupatoriums 7,e4 perfoliatum and purpureum1 the white and the purple boneset7 and of the blue-spiked ,verbena are very characteristic1 as are also several species of ,cassia 7,carolina coffee1 etc417 and the swamp rose-mallow4 ,upland and ,lowland ,vegetation in the ,arid and ,humid ,regions4--,in the humid countries there is commonly a marked difference between the vegetation of the uplands and lowlands1 arising not merely from the difference in the moisture supply1 but evidently of a specific nature4 ,when we discuss the characteristic plants in detail1 it becomes obvious that it is lime vegetation that1 in most cases1 forms the characteristic differences between upland and lowland forest growth2 a natural consequence of the leaching-down of the lime from the higher land to the lower levels4 ,by way of counter-proof we find that when the uplands themselves are of a calcareous nature1 a part at least of the lowland flora ascends into them4 ,as prominent examples may be mentioned the ,tulip tree 7,liriodendron71 black walnut1 ash1 ,kentucky coffee tree1 ,hercules' club1 etc41 which are lowland trees over the greater part of their area of occurrence2 but in the loess or ,cane hills bordering the ,mississippi and its larger tributaries1 as well as in the limestone regions of the southwestern and western states1 are conspicuous in the uplands as well4 ,the tall southern cane 7,arundinaria macrosperma71 usually considered a plant of the low river bottoms1 originally covered the loess or 8,cane hills0 of the lower ,mississippi1 with their highly calcareous soils4 ,the same is true of many other trees and shrubs characterizing limy lands4 ,of course there are some whose habitat is dependent upon the concurrent presence of both lime and moisture1 such as the sycamore1 cottonwood1 hackberry1 pawpaw1 etc41 which are naturally found only in stream bottoms or on low hammocks4 ,in the arid region1 on the contrary1 the main difference in upland and lowland vegetation is 7outside of mountain influences7 entirely referable to moisture-conditions2 the proof being that so soon as the uplands are irrigated the lowland flora takes possession4 ,both uplands and lowlands being abundantly calcareous1 there then is no cause for any material differences4 ,this substantial uniformity of upland and lowland plant growth is particularly striking in the comparatively restricted floras of ,eastern ,oregon and ,washington1 and in ,montana1 where the more luxuriant growth of the valleys is almost the only contrast seen when their vegetation is compared with that of the uplands adjacent4 ,forms of ,deciduous ,trees in the ,arid ,regions4--,since1 as shown above1 the soils of the arid regions are almost throughout calcareous1 we should expect that the forms of the native trees would in general conform to the rule given above4 ,as regards the deciduous trees this is very generally true3 ,we rarely see on the ,pacific slope1 south of ,oregon1 anything to compare with the tall oaks of the ,atlantic forests4 ,the native oaks are as a rule of low1 spreading growth1 with stout1 short trunks2 and as they rarely form dense forests1 the timbered areas have an orchard-like appearance1 characteristic of the landscapes of the arid region1 from the ,mezquit ,plains of ,texas to ,eastern ,oregon and ,washington4 ,only where a very abundant supply of moisture prevails do we find occasional exceptions4 ,the trees of the humid region when transplanted to ,california have a perverse tendency to branch low1 so that only the most persistent trimming-up will induce them to form trunks at all like those found in their native climes4 ,in some cases no amount of trimming will result in the formation of anything more than bushes4 ,it may be objected that the arid climate as such1 and not the calcareous nature of the soil1 is the cause of this tendency4 ,it is unquestionable that this low-branching habit is a distinct advantage to the plants1 whose trunks would otherwise be frequently scorched by the hot summer sun2 as happens when ,eastern settlers try to grow 8standard0 fruit trees1 with the result that a 8sore10 or sunburnt streak is formed on the southwest side of the exposed trunk4 ,all orchard trees should therefore be pruned 8vase-shape0 in arid climates1 partly for this1 partly for other reasons4 ,but this cannot explain the fact that seedlings from eastern acorns act precisely as do acclimated trees2 so that it is not a case of the survival of the fittest to endure arid conditions4 ,tall ,growths of ,conifers4 ,moreover1 while the rule holds good with almost all deciduous trees1 it is not applicable to the ,conifers2 which in the case of the ,sequoias 7redwoods and 8big-trees071 sugar pine and others1 exemplify some of the tallest growths known in the world4 ,the ,eastern ,cedar or ,juniper grows tall only on sufficiently calcareous soils1 and in the ,mississippi ,valley states at least1 wherever it occurs is an unfailing indication of calcareous lands4 ,the extended occurrence of the spruce on the ,allegheny ,ranges1 where limestone formations prevail so largely1 seems to indicate a similar preference for calcareous lands4 ,and this is certainly true of the black locust1 which reaches its extreme southern range in the cretaceous hills of ,northeastern ,mississippi1 showing the stout1 stocky form it also assumes when planted in the calcareous black-prairie lands of ,illinois4 ,herbaceous ,plants as ,soil ,indicators4 ,while herbaceous plants are not as generally considered by land-seekers in judging of soil fertility and character1 it goes without saying that very many are quite as characteristic as the tree vegetation1 especially when deep-rooting1 so as not to indicate merely the character of a few inches of surface soil4 ,in the ,middle ,west of the ,united ,states especially1 a large number of the ,composit serve as marks of high productive capacity4 ,this is particularly true of the larger species of the sunflower tribe1 among which ,helianthus grosse-serratus and doronicoides are perhaps the most generally notable2 while farther west1 beginning with ,kansas1 the 8,sunflower ,state10 and its northern neighbor1 ,h4 annuus1 whether native or introduced1 becomes conspicuous also4 ,the ,silphiums 7compass sunflowers7 have nearly the same significance1 ,s4 laciniatum and perfoliatum being prominent on the prairies of ,illinois and ,indiana2 but in land under cultivation they are mostly replaced by a luxuriant growth of the ,ragweed1 ,ambrosia trifida4 ,various species of ,bidens 7beggar ticks71 notably the ,b4 aristata and cernua1 accompany the true sunflowers in the lower grounds of these regions1 as do also ,heliopsis laevis1 ,coreopsis triperis and ,rudbeckia 7,obeliscaria7 pinnata4 ,rudbeckia hirta and purpurea1 though also occurring on rich soils1 are not characteristic of them4 ,the larger species of golden rods 7,solidago71 notably ,s4 canadensis1 rigida and speciosa 7not ordinarily distinguished by farmers7 share substantially the distribution of the large sunflowers mentioned above4 ,of the ,asters1 only ,a4 nov-angli serves as a reliable guide to high-class lands in the ,middle ,west1#aie but a very copious growth of asters and solidago of various species is always a welcome indication of land quality1 and indicates soils of good lime content1 if not absolutely calcareous4 #aie ,in view of its specific designation and the reputed poverty of ,new ,england soils1 this is rather unexpected4 ,leguminous ,plants4--,it is generally understood that most leguminous plants1 and among them especially the clovers1 indicate rich1 or rather1 calcareous lands4 ,the very large proportion of lime contained in the ash of legumes at once creates this presumption1 which is fully confirmed by experience so far as our ordinary culture plants of that relationship are concerned4 ,the favoring effect of lime on the development of bacteria1 so essential to the full development of cultivated legumes1 has already been referred to4 ,the favoring effect of gypsum sown even in small amounts with clover and other legumes1 may probably be referable to the known action of that salt in promoting nitrification1 which in the first stages of leguminous growth is so highly favorable to a vigorous and early start of the crop1 and to a more copious production of the nitrogen-assimilating nodules4 ,the quick change noted in meadows and pastures of languishing production so soon as moderately limed1 by the appearance of clover among the herbage1 at once reminds us that the ,rhizobia do not flourish in acid lands4 ,the great prevalence of leguminous plants of all kinds in the arid region--clovers 7not fewer than twenty-three species in ,california alone71 ,lupins1 ,astragalus and related genera1 at once remind us of the universal prevalence of calcareous soils in these regions1 as shown above4 ,mutatis mutandis1 we find precisely the same general facts in the arid regions of the other continents4 ,nevertheless1 it must be kept in mind that not all plants of the leguminous order are positively 8calciphile40 ,within the ,united ,states1 it is especially the genera ,desmodium 7,meibomia7 and ,lespedeza1 which are very numerously represented in the long-leaf pine region of ,mississippi1 where the soils are so poor in lime4 ,whether under these conditions these plants develop the rhizobian nodules1 has not1 so far as the writer is aware1 been definitely observed4 ,certain it is that quite a number of these plants occur on both calcareous and non-calcareous soils1 and on the latter assume a much more vigorous development than in the pine woods4 ,but it is evident that they1 with a few others 7e4 g4 ,galactia mollis1 ,cassia chamcrista and nictitans7 are more or less indifferent to the lime-content of soils1 and cannot therefore be relied upon in judging the quality of lands4 ,in ,mississippi and northern ,alabama1 the ,tephrosia virginica 78devil's shoestring071 associated with chestnut and short-leaved pine1 is characteristic of the poorest non-calcareous lands1 and bears seeds but very scantily4 ,it disappears so soon as calcareous lands are approached1 together with the chestnut tree4 ,,european ,,observations ,,and ,,views ,,on ,,plant ,,distribution ,,and ,,its ,,controlling ,,causes4 ,the writer has thus far presented and discussed mainly his own observations made in the ,united ,states1 without reference to the previous and contemporaneous work on the same subject in ,europe4 ,there arose certain discrepancies which could not well be explained without a previous full consideration of ,american conditions4 ,as is well known1 for nearly twenty years the accepted theory in ,europe was that of ,thurman1#aif which attributes the distribution of the native floras entirely to physical conditions2 thus anticipating by more than half a century the corresponding hypothesis lately brought forward by the ,u4 ,s4 ,bureau of ,soils4 ,thurmann classes plants simply as hydrophile and xerophile1 thus differing from most of our modern ecologists merely in omitting the transition phase of 8mesophytes10 which now serves as a convenient pigeon-hole for an indefinite variety of plants4 #aif ,essai de ,phytostatique applique la chaine du ,jura et aux contres voisines4 #b vols4 #hvo4 ,berne1 #ahdi4 ,while gradually many were led by their observations to doubt the correctness of ,thurmann's exclusive physical theory1 ,fliche and ,grandeau#aig were apparently the first to impair by their investigations the confidence in the accepted view4 ,they investigated exhaustively the conditions under which the maritime pine and the chestnut tree1 both antagonistic to lime1 would flourish1 and proved that the presence of any considerable amount of lime in the land would cause them to languish or die1 although the physical conditions so far as ascertainable were exactly alike4 ,it is interesting to note what were the lime-percentages which caused these differences2 viz41 for the 8non-calcareous0 soil and subsoil1 respectively1 4#ce and 4#bj2 for the calcareous land1 #c4be and #bd4jd1 the latter evidently being decidedly 8marly40 ,the composition of the ash of these trees is very instructive1 and is therefore given in full4 ,alongside of the ash of the maritime pine on the two soils is given that of the ,corsican pine1 a lime-loving tree4 ,,composition ,,of ,,pine ,,ashes ,,on ,,calcareous ,,and ,,non-,,calcareous ,,lands4 ---------------------------------------- ---------------------- ,,maritime ,,pine1 ,,corsican ,,pine1 ,,pinus ,,pinaster4 ,,pinus ,,laricio4 ---------------------------------------- --------------------- ,on non-calcareous,on calcareous,on calcareous soil4 soil4 soil4 ,potash #af4jd #d4ie #ac4ef ,soda #a4ia #b4eb #b4bd ,lime #dj4bj #ef4ae #di4ac ,magnesia #bj4ji #ah4hj #ac4di ,ferric ,oxid #c4hc #b4jg #c4bi ,silica #i4ah #f4db #g4ad ,phosphoric acid #i4jj #i4ad #aa4cc ---------------------------------------- --------------------- ,total #ajj4be #ajj4jd #ajj4ah ---------------------------------------- --------------------- ,ash per cent4 #a4cb #a4ed #b4de ---------------------------------------- --------------------- #aig ,annales de ,chimie et de ,physique1 #dme srie1 tome #bi2 ibid4 #eme srie1 ,tome #b4 ,also1 ibid1 tome #ah1 #ahgi4 ,it is very interesting to note in these analyses the inverse ratio in the absorption of potash and lime by the maritime pine1 which seems to be unable to defend itself against excessive absorption of lime and thus experiences a dearth of potash which naturally interferes with the formation of starch and chlorophyl2 hence probably induces the chlorosis so well known to occur on excessively calcareous soils4 ,the lime-loving ,corsican pine takes up a larger total amount of ash and more phosphoric acid1 and nearly three times as much potash1 but considerably less lime than did the maritime pine on the same calcareous soil4 ,the corresponding analyses made by ,fliche and ,grandeau1 of the leaves and wood of chestnut grown on the same two kinds of soils1 gave in general the same results2 and they add that the smaller content of iron absorbed by the calcifuge trees when grown on calcareous soil point also to a deleterious influence upon the normal formation of chlorophyl4 ,following ,fliche and ,grandeau1 ,bonnier#aih made corroborative tests by sowing seeds of the same plants1 both calciphile and calcifuge1 upon the two kinds of soils1 and noting the differences in their mode of growth and internal structure4 #aih ,bull4 de la ,socit ,botanique de ,france1 tome #bf1 #ahgi4 ,calciphile1 ,calcifuge and ,silicophile plants4 ,the subject has been somewhat exhaustively discussed by ,contejean#aii who enumerates and has classified under the three general heads of calciphile1 calcifuge and indifferent1 over #agjj species of ,european plants4 ,unfortunately he had but few soil analyses at his disposal1 and was inclined to consider as non-calcareous1 most soils that gave no effervescence with acids4 ,but notwithstanding this disadvantage so far as his contention of the efficacy of chemical soil-composition1 and especially of lime is concerned1 he disproves very effectually the physical theory of ,thurmann1 by numerous examples from ,france and elsewhere in ,europe2 and also disposes very definitely of the claim that there is a special class of 8silicophile0 plants4 ,he concludes that silica 7and sand7 is merely a neutral and inert medium which offers refuge to the plants 8expelled0 by lime2 and that clay similarly exerts no chemical but only a purely physical action4 ,that potash1 phosphoric acid and nitrogen1 while most essential as plant-foods1 exert otherwise little if any effect on general plant distribution4 ,he alludes similarly to magnesia2 and his final conclusion is that 8chemical are in general more potent than physical influences10 and that the most widely active influences are carbonate of lime and chlorid of sodium4 ,he does not1 of course1 deny the potent influence of moisture upon plant distribution4 #aii ,geographie botanique4 ,influence du terrain sur la vegetation4 ,baillre et ,fils1 ,paris1 #ahha1 #adc pp4 ,since these publications were made1 many observers have investigated the subject1 and the broad distinction between lime-loving or calciphile and lime-repelled or calcifuge plants has been very generally recognized and discussed3 but the cause of this discrimination by plants is still more or less the subject of controversy4 ,some still claim that the calcifuge plants 7such as the chestnut1 the huckleberries and whortle-berries1 the heather and many other ,ericace1 most sedges1 etc47 are repelled by calcareous lands because they need a large supply of silica1 which they suppose cannot well be assimilated in presence of much lime2 hence they also designate the calcifuge plants as 8silicophile02 while others attribute the preference of calciphile plants to the physical effects produced upon the soil by lime1 as outlined above 7chapter #bj1 page #cgi74 ,the contention that the presence of much lime in soils renders silica insoluble and hence unassimilable by plants1 is at once negatived by the fact that waters exceptionally rich in silica1 partly simply dissolved by carbonic acid1 partly in the form of water-soluble alkali-silicates1 are very abundantly found in the arid region4 ,this is especially the case in ,california1 where moreover a number of species of very rough-surfaced horsetail rushes and grasses prove the ready absorption of silica when wanted1 even in strongly calcareous soils4 ,but the question is whether the supposed class of silicophile plants is a reality or merely a theoretical fiction1 based upon the habit of speaking of 8siliceous0 soils as a class apart from other and especially heavier or clay soils4 ,as a matter of fact1 the siliceous soils usually so called are simply those poor in clay and lime--in other words1 8light0 lands1 the outcome of the weathering of quartzose rocks into sandy soils1 which in the humid region are always poor in lime because thoroughly leached4 ,in the arid region1 on the contrary1 sandy lands are quite commonly just as calcareous as the heavier soils1 and show no 8silicophile0 flora4 ,according to the writer's observations and views1 it being obvious that some plants are practically indifferent to the presence or absence of lime in the soil except in so far as it influences favorably the physical conditions1 moisture must always stand first as the condition of maximum crop production1 and as a conditio sine qua non of the best development of plants on all kinds of soils2 its best measure being a matter of special adaptation to each species4 ,but this being understood1 he agrees with ,contejean as to the commanding influence of lime in determining the adaptation of soils to plants1 both cultivated and wild4 ,at the same time1 it is obvious that the absence of the opportunity to observe really native vegetation1 adapted to the soils through ages1 has created for ,european observers difficulties which are readily solved where original native floras are available4 ,schimper#bjj says pointedly that observations prove that the differences between the location of plants on calcareous and siliceous soils are not constant1 but vary from province to province2 that e4 g41 the list of indifferent 7bodensteter7 plants for the ,alps do not hold good in the ,dauphin1 still less between the ,carpathians and ,skandinavia4 ,according to ,wahlenberg the following species are calciphile in the ,carpathians1 and according to ,christ indifferent in ,switzerland3 ,dryas octopetala1 ,saxifraga oppositifolia1 most of the leguminous species1 ,gentiana nivalis1 ,g4 tenella1 ,g4 verna1 ,erica carnea1 ,chamorchis alpina1 ,carex capillaris4 ,geum reptans is reported by ,bonnier to be exclusively calciphile on ,mont ,blanc1 exclusively silicophile in the ,dauphin2 indifferent in ,switzerland4 ,a great number of similar contradictions are reported by others as well1 and the entire subject thus becomes rather vague2 so that ,schimper and others suggest that climatic conditions may in part be responsible for these discrepancies4 #bjj ,pflanzengeographie1 p4 #aaa ff4 ,in all1 or nearly all these cases1 it is tacitly assumed that the underlying geological formation has essentially been the source of the soil1 and that its character is determined accordingly4 ,but this assumption is wholly arbitrary unless confirmed by actual direct examination4 ,a soil-formation overlying limestone on the slopes of a range may be wholly derived from non-calcareous formations lying at a higher elevation1 or may have been leached of its original lime-content by abundant rains4 ,the feldspars constituting rocks designated as granite1 may or may not be partially or wholly of the soda-lime instead of the potash series2 the mica may or may not be partially replaced by hornblende1 in which cases the soil would be calcareous to the extent of determining the character of the flora as calcifuge or calciphile1 without its being at all evident in the physical character of the soil1 which would still be 8granitic0 or 8siliceous40 ,such observations in order to be critically decisive1 clearly require that the observer should be1 not merely a systematic botanist1 nor a mere geologist or chemist1 but all these combined4 ,there is good reason to believe that most or all of these supposed contradictions would disappear before a critical physical and chemical examination of both the soils and the rocks from which they are supposed to have been derived4 ,contejean himself1 in placing so many of his long catalogue of plants into the doubtful groups1 suggests many cases in which the above considerations may explain the apparent discrepancies4 ,what is a calcareous soil8 ,the definition adopted for this volume has been given in a previous chapter 7chapter #ai1 page #cfg72 viz1 that a soil must be considered calcareous so soon as it naturally supports a calciphile flora--the 8lime vegetation0 so often referred to above and named in detail4 ,upon this basis it has been seen that some 7sandy7 soils containing only a little over one-tenth of one per cent of lime show all the characters and advantages of calcareous soils2 while in the case of heavy clay soils1 as has been shown1 the lime-percentage must rise to over one-half per cent to produce native lime growth4 ,while in the ,united ,states observations of the contrasts between calciphile and calcifuge floras are easily made in the field1 and the facts must attract the attention of any fairly qualified observer1 in ,europe they would have to be made the subject of special cultural investigation based upon soil analysis2 a procedure not yet fully accredited abroad1 any more than in the ,united ,states4 ,in a general way it has however been recognized by ,maercker1 as shown at the end of the preceding chapter4 ,how far this estimate was based upon ,american precedents1 can now be only conjectured4 ,certain it is that the ,european definition of calcareous soils remains to the present day a wholly different one from that stated above2 and from this have arisen the greater part of the doubts and differences of opinions among ,european botanists as to the classification of plants in relation to calcareous soils4 ,two per cent of lime 7equivalent to nearly double the amount of carbonate7 is the prevailing ,european postulate for a calcareous soil4 ,some go so far as to postulate effervescence with acids1 requiring about #e of the carbonate4 ,predominance of ,calcareous ,formations in ,europe4--,it is not generally recognized even among geologists how abnormally predominant are limestone formations in ,europe4 ,in all works on ,european agriculture we find the 8lime sand0 mentioned as a normal ingredient of soils1 specially provided for 7or against7 in the operations of soil examination4 ,its presence is the rule1 its absence the exception4 ,soils as poor in lime as are those of the long-leaf and short-leaf pine regions of the ,united ,states1 are there very exceptional and 7like the 8,haidebden0 of northern ,germany7 have long remained almost uncultivated4 ,calcareous soils being the rule in the regions of intense culture1 the ideas of both agriculturists and agricultural chemists have in ,europe1 in the main1 been based upon them as normal soils2 so that instead of comparing calcareous1 and non-calcareous soils properly speaking--i4 e41 such as would not bear native lime-vegetation--the majority of comparisons has actually been made between soils which1 in the ,american sense1 were all or chiefly within the calcareous class4 ,it is characteristic of this state of things that the injuriousness of an excess of lime is among the foremost themes of ,european 7especially ,french and ,english7 agricultural writers1 as against the beneficent effects prominently assigned to lime in ,america4 ,no such popular saying as that 8a lime country is a rich country0 exists in ,europe2 on the contrary1 we constantly hear1 and see in books1 the mention of 8poor chalk lands10 and in ,france especially the deleterious effects of excess of lime upon crops is the theme of remark4 ,excess of lime in their marly lands has been the despair of ,french vintners1 and ,viala was specially sent to ,america to find some vine to serve as a grafting stock which would resist the tendency to chlorosis which renders many of the ,american phylloxera-resistant vines useless to the viticulturists of ,france4 ,viala did not find such grapevines until he reached the cretaceous 7chalk7 area of ,texas1 where the native vines had long ago adapted themselves to marly soils2 and these vines have solved the problem for ,french viticulture4 ,and ,england1 ,france1 ,belgium and most of western ,europe are rich countries1 largely owing to their abundant limestone formations2 and it may be questioned whether1 had this been otherwise1 ,europe would so long have remained the center of civilization2 for starving populations are not a good substratum for high mental culture and progress4 ,it may equally be asked whether the invariably calcareous character of arid soils1 as heretofore shown1 has not1 together with their general high quality1 been largely a determining factor in the location and persistence of so many ancient civilizations in arid lands2 as outlined in chapter #ba1 page #dag4 ,in this connection1 the proper distinction between calcareous and non-calcareous soils passes from the domain of natural science to that of the history of human civilization4 ,,chapter ,,xxvi4 ,,the ,,vegetation ,,of ,,saline ,,and ,,alkali ,,lands4 ,marine ,saline ,lands4--,while the saline alluvial lands of the sea-coast differ both in their mode of origin and in their nature from the alkali soils or 8terrestrial saline lands10 as they have been called in ,europe1 their vegetation has in many respects a common character4 ,not only is there much similarity1 sometimes even identity1 in the kinds of plants inhabiting these lands1 but their saline ingredients induce certain changes of form and structure in plants not properly 8saline0 but more or less tolerant of soluble salts1 by which the saline or alkali character of the lands may be recognized4 ,just as in the case of lime we must distinguish between the plants definitely repelled by a large amount of this substance in the soil 7calcifuge71 while others prefer the soils in which lime is abundant 7calciphile71 and still others appear to be indifferent to its presence and are governed in their habitat by the physical conditions presented3 so in the case of saline lands the salts may attract or repel certain plants4 ,the latter class is much the largest2 while there is also a number of plants which are more or less indifferent to the presence of salts1 provided these be not in very great excess4 ,such plants constitute the next-largest class2 while those attracted by salts1 and whose welfare is conditioned upon their presence1 are comparatively few in number1 and still fewer among them are of economic importance4 ,hence the soluble salts have largely a negative importance for agriculture2 the question usually being how to utilize the land until the undesirable surplus of salts can be got rid of1 partially or wholly1 as the case may be2 the former usually in seashore lands1 the latter in the alkali lands proper2 in which a small remnant1 not sufficient to injure crop plants1 is usually desirable 7see chap4 #bc1 p4 #dfb74 ,general ,character of ,saline ,vegetation4--,those familiar with seashore marshes cannot fail to note the fleshiness and succulence of the characteristic plants4 ,this 8incrassation0 belongs not only to the saline flora proper1 but is acquired to a greater or less degree when plants not ordinarily at home on saline ground are transferred to it artificially1 or by saline overflows2 while at the same time the leaves usually become smaller1 and the growth more compact4 ,correspondingly1 when saline plants are transferred to non-saline ground1 the leaves generally become thinner and larger1 and the growth more slender4 ,the well-known 8,russian thistle0 is a case in point1 as is also its close relative1 the soda saltwort 7,salsola soda72 although the latter does not often venture as far from the saline lands as does the former 7,salsola kali tragus71 which now seems to have become a world-wide weed1 with only a shade of preference for alkali lands4 ,structural and ,functional ,differences ,caused by ,saline ,solutions4--,it has been definitely shown by the investigations of ,schimper1 ,brick1 ,hoffmann1 ,lesage1 ,rosenberg and others1 that the peculiarities or changes of structure brought about by saline solutions are essentially those pertaining to xerophile 7drought-enduring7 vegetation2 which in general tend to the diminution of evaporation from the plant surfaces4 ,it may be said1 roughly speaking1 that the absorption of water by the roots begins to diminish so soon as the concentration of the saline solution approaches or exceeds one-half of one per cent2 while when it rises as high as three per cent1 water-absorption by the roots ceases even in the wettest soils1 and the plant suffers from drought quite as much as from any directly injurious effects of the salts4 ,different plants of course differ in the measure of concentration which brings about these phenomena1 which vary also with the character of the soluble salts4 ,it is stated that injurious or useless salts like common salt act at lower concentrations than e4 g41 saltpeter1 which is useful4 ,the difference in external structure are3 diminution of the size of leaves1 assumption of cylindrical or spinous forms1 sinking-in of the breathing pores below the outer surface1 dense hairy covering1 resinous exudations1 etc4 ,internally we find that xerophile plants have developed on their upper or outer leaf-surfaces instead of one1 several layers of 8palisade0 7long and erect1 closely-packed7 cells1 through which transpiration is extremely slow1 as is also the transmission of heat4 ,when salt-tolerant plants are grown on saline soils1 their palisade cells are relatively lengthened4 ,coincident with these external means for the retardation of evaporation1 the leaves of xerophiles are frequently supplied with special water-storage cells1 which supply moisture for the physiological processes when the root supply falls short4 ,the cactus tribe and similar-looking plants are examples of the latter provision1 which causes even animals suffering from thirst to resort to them1 although they eschew the saline vegetation4 ,absorption of the ,salts4--,the true halophytes or exclusive salt plants1 which refuse to grow on lands not containing a large proportions of salt1 often absorb so much salt that on drying it blooms out on their surface2 they usually have1 even when green1 a distinctly salty taste1 and their ash is rich in chlorids1 specially of sodium4 ,such is the case of the samphire1 common in saline marshes everywhere4 ,the total ash is usually very high1 often varying with the salinity of the water or soil in which they have grown4 ,thus the salt-content of the ash of samphire may vary by several per cent4 ,in other cases1 as in that of one of the ,australian saltbushes investigated at the ,california station1 neither the ash content nor the composition of the ash varies materially whether the plant be grown on strong alkali land1 or on uplands whose total saline content does not exceed 7in four feet depth7 4#jae or #bejj pounds per acre4 ,the following table gives the composition of the ash of this saltbush alongside of that of two other prominent alkali-plants of the same relationship1 occurring1 one in the ,san ,joaquin valley of ,california1 in strongly saline lands1 the other in the ,great ,basin region of the interior1 on lands strongly impregnated with carbonate of soda4 ,all these1 it will be seen1 take up very large amounts of sodium salts1 notably the chlorid2 the ,australian plant most so1 the 8greasewood0 of the ,great ,basin least so2 a large proportion of the alkali salts being evidently1 in the latter case1 contained in the form of organic salts1 which in the ash become carbonates4 ,,analyses ,,of ,,ashes ,,of ,,saline ,,and ,,alkali ,,plants4 7,a7 ,australian ,saltbush1 ,atriplex semibaccata4 7,b7 ,bushy ,samphire1 ,allenrolfea occidentalis4 7,c7 ,greasewood1 ,sarcobatus vermiculatus4 7,d7 ,saltgrass1 ,distichlis spicata4 7,e7 ,tussock grass1 ,sporobolus airodies4 7,f7 ,prickly ,pear1 ,opuntia macrocentra4 7,a7 7,b7 7,c7 7,d7 7,e7 7,f7 ---------------------------------------- -------------------- ,ash1 air-dried plant1 4 #ai4cg #ab4jc #ac4ha #aa4fa #g4ii #bd4ah ---------------------------------------- -------------------- ,potash 7,k,o7 #aa4db #ah4ec #cj4aa #c4cj #e4gh #a4fa ,soda 7,na,o7 #ce4ci #ci4de #cb4eh #b4ch #e4ae #b4gf ,lime 7,ca,o7 #e4ge #a4cf #h4gj #e4be #h4je #fe4ff ,magnesia 7,mg,o7 #c4bc #a4ji #a4ji #b4ie #d4ae #bf4gj ---------------------------------------- -------------------- ,br4 ox4 of ,manganese 7,mn,o7 4#bb 4#af 4#be ---------------------------------------- -------------------- ,peroxid of ,iron 7,fe,o7 #c4cc #g4jf not #b4bb #b4ci #a4ai ,alumina 7,al,o7 det'd4 ---------------------------------------- -------------------- ,silica #af4bd #aa4ha #d4jj #gh4gc #ff4gi 4#ha ,phosphoric acid 7,p,o7 #b4hj #c4ea #e4fj 4#hc #a4be 4#dg ,sulfuric acid 7,,so7 #b4fd #d4ic #e4ij #c4bj #d4eb 4#fd ,chlorin1 percent #bd4cc #ae4cj #aa4jj #a4dj #b4ac 4#ba ---------------------------------------- -------------------- ,totals #aje4ceajc4jd #ii4giajj4caajj4dfajj4je ,less excess1 ,o3 ,cl #e4ce #c4be #b4ej 4#ca 4#df 4#je ---------------------------------------- -------------------- ,true totals #ajj4jj #ii4gi #ig4biajj4jjajj4jjajj4jj ---------------------------------------- -------------------- 7,g7 ,shad scale1 ,atriplex canescens4 7,h7 ,alfalfa ,hay4 7,cal47 7,i7 ,timothy ,hay4 ,,of ,,forage ,,crops4 7,g7 7,h7 7,i7 ---------------------------------------- ----------- ,ash1 air-dried plant1 4 #d4bc #i4he #f4ae ---------------------------------------- ---------- ,potash 7,k,o7 #be4ag #dc4gb #bh4hj ,soda 7,na,o7 #f4bc #d4dh #b4gj ,lime 7,ca,o7 #be4ig #bj4ea #i4hc ,magnesia 7,mg,o7 #af4fc #b4ef #c4fj ,br4 ox4 of ,manganese 7,mn,o7 4#ea ---------------------------------------- ----------- ,peroxid of ,iron 7,fe,o7 #e4hi #b4ie ,alumina 7,al,o7 ---------------------------------------- ----------- ,silica #aa4id #e4hg #ce4jj ,phosphoric acid 7,p,o7 #c4aa #e4jj #aj4hj ,sulfuric acid 7,,so7 #d4ic #f4ib #c4ij ,chlorin1 percent #b4jg #aj4be #e4jj ---------------------------------------- ----------- ,totals #ajj4de #ajb4bf #ii4gj ,less excess1 ,o3 ,cl 4#de #bb4f #a4ac ---------------------------------------- ----------- ,true totals #ajj4jj #ajj4jj #ih4eg ---------------------------------------- ----------- ,jaffa1 ,cal4 ,st'n4 ,rept4 #ahid-ie1 p4 #afi4 ,goss1 ,new ,mex4 ,st'n4 ,bull4 ,no4 #dd2 recalculated4 ,it will be noted that the saltbush hay contains nearly one-fifth of its 7air-dry7 weight of ash1 of which nearly #dj is common salt4 ,it therefore has a distinctly salty taste1 and is always moist to the touch1 containing-ordinarily over #ae of moisture4 ,it is therefore much liked by stock when fed intermixed with other hay1 and thus supplies all the salt needed by cattle4 ,the greasewood is much less liked by stock1 and bushy samphire is wholly rejected by them4 ,comparing with these fleshy plants the ash of the two grasses1 the first a world-wide 8salt grass10 the other a common grass of the ,american arid region1 we note that not only do they contain much less soluble ash than the saltbushes1 but especially much smaller amounts of sodium salts2 proving that even when growing in company with the saltbushes on strongly impregnated land1 they can repel from absorption these to them useless or injurious salts4 ,but in the case of the 8shad scale10 also a 8saltbush0 of the ,great ,basin1 the ash-content is remarkably low--only about one-fifth of that of its ,australian relative--and it differs widely from the latter in having but a very low proportion of soda1 and a very high one of lime and potash1 approaching in these respects to our usual forage crops2 and being also fairly rich in nitrogen1 it forms acceptable browsing when other pasture plants are scarce4 ,it therefore does not exert the laxative action produced by the exclusive feeding on the more saline herbages4 ,the exceptionally high ash-content of the cactus or prickly pear1 also given in the table1 arises1 it will be noted1 not from the soluble salts but from the absorption of extraordinarily high proportions of lime and magnesia4 ,owing probably to the latter substance1 and also the oxalate form in which lime is usually found in the cactus tribe1 this plant when used as forage is also somewhat laxative4 ,altogether1 this table offers remarkable examples of wide differences in the kind and amount of ash ingredients absorbed by plants growing upon similar soils and under identical climatic conditions2 indicating a selective power which no merely physical theory of soil-action in plant growth can explain4 ,injury to ,plants from the ,various ,salts4--,the early observers1 especially ,contejean1 were predisposed from their observations of lime on vegetation to ascribe the action of salt upon marine vegetation to the sodium component4 ,but the wide differences in the effects of different sodium compounds1 notably of common salt and ,glaubers salt1 led some to the conclusion that the acidic ingredients are the chief determining factors4 ,moreover1 it was soon found that a single salt is more injurious than a mixture of several1 such as sea water4 ,this also led to the inference that the varying degree of dissociation of these salts essentially influences the effects4 ,kearney and ,cameron have investigated these relations1#bja and have by artificial cultures in solutions of varying concentration and composition studied the behavior of plant roots and the limits of their endurance4 ,they found for the several salts occurring in alkali soils1 taken separately1 the following figures1 in #ajj1jjj parts of water3 ,magnesium sulfate #g 8 chlorid #ab ,sodium carbonate #bf 8 sulfate #ec 8 chlorid #aaf 8 bicarbonate #afg ,calcium chlorid #a1cgg #bja ,report ,no4 #ga1 ,u4 ,s4 ,dep't4 of ,agriculture1 #aijb4 ,it will be noted that in many respects the results given in this table stand in marked contrast to the facts observed in alkali lands everywhere2 and therefore while interesting physiologically1 are not directly applicable to practice4 ,magnesium sulfate1 which according to this table is the most injurious of all1 is a common ingredient of alkali lands from ,wyoming to ,new ,mexico1 as also is sodium sulfate2 yet there1 as well as in the ,musselshell valley in ,montana1 and at many other points1 it shows no specially deleterious action either upon native or cultivated plants1 and in ,europe as well as in ,new ,england the mineral kieserite is freely used as a fertilizer at many points4 ,that sodium sulfate should be twice as harmful as sodium chlorid or common salt1 and half as harmful as the carbonate or black alkali1 is again wholly contrary to actual experience1 which as shown elsewhere in this chapter1 indicates that the majority of plants will tolerate between three and four times as much of sodium sulfate as of common salt2 while the ratio of tolerance as against the carbonate seems sometimes to rise as high as ten to one4 ,it is clearly evident1 however1 that it is the metallic or basic ingredient that in the main determines the toxicity of these salts4 ,the universal presence of lime in some form in all alkali lands doubtless explains the discrepancies mentioned1 since lime is especially potent in counteracting the injurious effects2 thus throwing additional light upon the importance of the lime-content of alkali soils proper1 and also upon the causes of the narrow limitations of the littoral 7marine saline7 flora2 inasmuch as1 unlike alkali soils1 marine alluvial lands are by no means always calcareous4 ,cameron goes so far as to attribute the favorable effects of gypsum upon black alkali not so much to the conversion of the latter into neutral sulfate1 as to the effect of gypsum solution in counteracting the saline effects4 ,this interpretation1 however1 seems rather far-fetched1 since there can be no question about the double decomposition of gypsum with carbonate of soda2 or the intense injuriousness of carbonate of soda in the actual corrosion of vegetable tissues4 ,the corresponding protective influence of various salts1 more especially of those of lime1 against the injurious effects of pure common salt on marine animals1 has already been mentioned 7chapter #bj1 page #chj71 and later investigations by ,osterhout on marine alg1 show the same relation to hold true for them also4 ,reclamation of ,marine ,saline ,lands for ,culture4--,the reclamation of sea-coast lands and marshes for agricultural use is based in general upon the same methods as those already outlined for alkali lands in chapter #bj2 except that in this case no chemical neutralization is possible1 since common salt cannot be changed by any practically feasible means4 ,it must be removed by leaching1 and this1 in the humid countries in which such reclamations have chiefly been made1 is usually done by the agency of rains1 aided by ditching4 ,the 8polder0 lands thus reclaimed along the shores of the ,north ,sea1 from ,belgium to ,prussia1 are especially esteemed for their productiveness1 doubtless owing to the alluvium of the numerous rivers tributary to that sea1 which is distributed along its shores and in the numerous inlets and bays4 ,the tides are of course excluded by dikes provided with gates opening outward1 so as to permit of the outflow of rain- or irrigation-water used for leaching purposes4 ,out of reach of stream alluvium no exceptional fertility is to be expected of seashore lands1 which then commonly assume the form of sand dunes or bars1 incapable of nourishing any cultural vegetation4 ,of the latter1 the groups listed below as tolerant of alkali salts1 may also be considered with reference to reclaimed seashore lands2 the first cereal to succeed being usually barley1 the first root crop1 beets4 ,asparagus is also available while salt is being leached out4 ,,the ,,vegetation ,,of ,,alkali ,,lands4 ,the general character of alkali-land vegetation is not unlike that of saline seashore lands2 some species of plants are common to both1 but the alkali lands harbor a much greater variety of plants1 owing to the differences in climates and soils as well as to the nature of the impregnating salts4 ,moreover1 owing to the very causes which underlie the presence of these salts1 viz1 aridity1 the xerophile or dry-land character of the alkali-land flora is much more pronounced than that of the saline seashore vegetation4 ,in view of the very complex conditions1 the discussion of the alkali-flora is of necessity much more complex than that of the marine group2 and the data for its full elucidation with respect to the nature of the soils and salts are as yet very incomplete4 ,,reclaimable ,,and ,,irreclaimable ,,alkali ,,lands ,,as ,,distinguished ,,by ,,their ,,natural ,,vegetation4 ,while1 as shown above 7chapter #bj71 the adaptation or non-adaptation of particular alkali lands to certain cultures may be determined by sampling the soil and subjecting the leachings to chemical analysis1 it is obviously desirable that some other means1 if possible available to the farmer himself1 should be found to determine the reclaimability and adaptation of such lands for general or special cultures4 ,in alkali lands1 as in others1 the natural plant-growth affords such means1 both as regards the quality and quantity of the saline ingredients4 ,the most superficial observation shows that certain plants indicate extremely strong alkali lands where they occupy the ground alone2 others indicate pre-eminently the presence of common salt2 the presence or absence of still others form definite or probable indications of reclaimability or non-reclaimability4 ,many such characteristic plants are well known to and readily recognized by the farmers of the alkali districts4 8,alkali weeds0 are commonly spoken of almost everywhere2 but the meaning of this term--i4 e41 the kind of plant designated thereby--varies materially from place to place1 according to climate as well as the quality of the soil4 ,it is obvious that if these characteristic plants were definitely observed1 described and named1 while also ascertaining the amount and kind of alkali they indicate as existing in the land1 lists could be formed for the several regions1 which would indicate1 in a manner intelligible to the farmer himself1 the kind and degree of impregnation with which he would have to deal in the reclamation work2 thus enabling him to go to work on the basis of his own judgment1 without previous chemical examination4 ,a study of the lands of ,california having this purpose in view1 was undertaken in the years #ahih and #ahii by the ,california ,station2 but lack of funds prevented its prosecution beyond the ascertainment of those plants the abundant occurrence of which prove the land to be irreclaimable without the use of the universal remedy1 viz1 underdrainage1 which on the large scale is usually beyond the means of the land-seeker4 ,the botanical field work and collection of soil samples was carried out by ,mr4 ,jos4 ,burtt ,davy2 the chemical work1 as heretofore1 being done by ,dr4 ,r4 ,h4 ,loughridge4 ,the results here reported are therefore essentially their joint work4 ,it is hoped that in the future1 a more comprehensive study and close comparison of the native vegetation with the chemical determination of the quality and kind of alkali corresponding to certain plants1 or groups of plants1 naturally occurring on the land1 may enable us to come to a sufficiently close estimate of the nature and capabilities of the latter from the native vegetation alone1 or with the aid of test plants purposely grown1 for the farmers' purposes4 ,plants ,indicating ,irreclaimable ,lands4--,the plants herein-after mentioned and figured are1 then1 to be understood as indicating1 whenever they occupy the ground as an abundant and luxuriant growth1 that such land is irreclaimable for ordinary crops1 unless underdrained for the purpose of washing out surplus salts4 ,the occurrence merely of scattered1 more or less stunted individuals of these plants1 while a sure indication of the presence of alkali salts1 does not necessarily show that the land is irreclaimable4 ,the plants which may best serve as such indicators in ,california are the following3 ,tussock-grass 7,sporobolus airoides ,torr471 ,fig4 #hb4 ,bushy ,samphire 7,allenrolfea occidentalis ,wats4 ,ktze471 ,fig4 #hc4 ,dwarf ,samphire 7,salicornia subterminalis ,parish1 and other species71 ,fig4 #hd4 ,saltwort 7,suaeda torreyana ,wats41 and ,s4 suffrutescens1 ,wats471 ,fig4 #he4 ,greasewood 7,sarcobatus vermiculatus ,hook4 ,torr471 ,fig4 #hf4 ,alkali-heath 7,frankenia grandifolia campestris ,gray71 ,fig4 #hg4 ,cressa 7,cressa truxillensis ,choisy71 ,fig4 #hh1 perhaps identical with ,c4 cretica auct4 ,saltgrass 7,distichlis spicata71 ,fig4 #hi4 ,,tussock-,,grass 7,sporobolus airoides1 ,torr472 ,fig4 #hb4 78,bunch grass0 of ,new ,mexico74 ,the three sets of ,tussock-grass soil which have been analyzed show that the total amount of all salts present is in no case less than #di1jjj pounds per acre1 to a depth of four feet2 and that it sometimes reaches the extraordinarily high figure of #dii1jjj pounds4 ,of these amounts the neutral salts 7,glauber's salt and common salt7 are usually in the heaviest proportion 7,glauber's salt1 #ai1fjj to #cbc1jjj pounds per acre2 common salt1 #c1ejj to #agb1hjj72 the corrosive salsoda varying from #c1jjj to #dd1jjj pounds4--,tussock-grass apparently cannot persist in ground which is periodically flooded4 ,it is of special importance because it is an acceptable forage for stock4 ,tussock-grass is a prevalent alkali-indicator in the hot1 arid portions of the interior1 from the upper ,san ,joaquin ,valley1 the ,mojave desert1 and southward2 also through southern ,nevada and ,utah as far east as ,kansas and ,nebraska4 ,in the ,san ,joaquin ,valley it has not been found farther north than the ,tulare plains1 although east of ,reno it occurs near ,reno4 ,coville observes that in the ,death ,valley region 8it is confined principally to altitudes below #a1jjj meters0 7#c1bhj feet74 ,hillman1 however1 reports it from near ,reno1 ,nevada1 at an altitude which cannot be much less than #d1ejj feet4 ,illustration3 ,,fig4 #hb4--,tussock-,grass--,sporobolus airoides ,torr4 ,the tussocks formed by this grass1 which are unfortunately not shown in the figure1 sometimes appear as veritable little grass trees1 and when denuded by the browsing of cattle seem like trunks #ah and #bj inches high4 ,it is therefore very easily recognized2 but it should be noted that in view of the extraordinary range of its tolerance1 shown above1 its scattered occurrence does not necessarily indicate irreclaimable land4 ,,bushy ,,samphire4 7,allenrolfea occidentalis ,wats4 ,g4 ,ktze47 ,,fig4 #hc44 ,this plant is locally called greasewood1 but as this name is much more commonly used for ,sarcobatus vermiculatus1 it seems best to call ,allenrolfea 8bushy samphire10 as it closely resembles the true samphire 7,salicornia74 ,bushy ,samphire usually grows in low sinks1 in clay soil which in winter is excessively wet1 and in summer becomes a 8dry bog40 ,wherever the plant grows luxuriantly the salt content is invariably high1 the total salts varying from #cbg1jjj pounds per acre1 to a depth of three feet1 to #did1ebj pounds in four feet4 ,the salts consist mainly of ,glauber's and common salts 7a maximum of about #bge1jjj pounds each72 salsoda varies from #b1cfj to #d1hjj pounds per acre4 ,the percentage of common salt and total salts is higher than for any other plant investigated1 and the content of ,glauber's salt is also excessive4 ,the areas over which this plant grows must therefore be considered among the most hopeless of alkali lands1 for although its salts are 8white10 submergence during winter precludes the growth of ,australian saltbushes4 ,full underdrainage alone could reclaim the soil-areas it occupies4 ,bushy ,samphire is common on low-lying alkali lands in the upper ,san ,joaquin ,valley1 ,california1 and extends northward along the eastern slopes of the ,coast ,range to ,suisun ,bay4 ,it is also abundant in the ,death ,valley region1 apparently overlapping the southward range of the ,sarcobatus1 the greasewood properly so-called4 ,,dwarf ,,samphire 7,salicornia subterminalis1 ,parish1 and other species of the interior72 ,fig4 #hd4 ,illustration3 ,,fig4 #hc4--;,bushy ,samphire--,allenrolfea occidentalis 7,s4 ,wats47 ,g4 ,ktze4 ,illustration3 ,,fig4 #hd4--,salicornia subterminalis4 ,alkali samphire4 ,a4 ,much-branched form4 ,b4 ,slender form4 ,c4 ,flower with the perianth removed showing the simple pistil and the two stamens4 ,d4 ,portion of flowering spike1 showing two joints4 ,the flowers are impressed in the joints in opposite clusters of three4 ,in each cluster the middle flower stands slightly above the two laterals as shown in the lower joint4 ,the three or four species of ,dwarf ,samphire which grow in the interior valleys of the ,state are not usually very abundant1 save locally4 ,wherever the species do occur1 however1 they may be considered as indicating excessively saline soils4 ,dwarf ,samphire soil has shown a total salt content of #dda1hhj pounds per acre in a depth of four feet4 ,the neutral ,glauber's salt amounts to #cad1jjj pounds1 almost as much as in ,tussock-grass soil2 common salt up to #abe1fdj pounds while the salsoda varies from #b1bjj to #ab1jjj4 ,we may consider the plant as indicative of almost the highest percentage of common salt1 ,glauber's salt and total salts4 ,like the preceding species it indicates land strongly charged with salts1 more especially common salt1 and susceptible to cultivation only after reclamation by underdrainage4 ,salicornia subterminalis1 ,s4 herbacea 7,l471 ,s4 mucronata1 and another species1 all occurring inland1 differ materially in habit and botanical characters from the one so conspicuous in submerged salt marshes along the seashore2 but all alike indicate strongly saline soils1 reclaimable only by thorough drainage4 ,,saltwort 7,suaeda torreyana1 ,wats41 ,s4 suffrutescens1 ,wats41 and perhaps one other species72 ,fig4 #he4 ,samples of saltwort soil from ,bakersfield and ,byron ,springs1 ,california1 taken to a depth of one foot and three feet respectively1 show that this plant grows luxuriantly in a soil containing #acj1jjj pounds of total salts per acre in the first foot1 and with #aj1dhj pounds of the noxious salsoda1 and #ci1gfj pounds of common salt in three feet2 while only a sparse growth is found on soils containing only #c1gjj pounds of salts in three feet4 ,it thus appears to indicate a lower percentage of salsoda than does ,greasewood1 but a higher percentage than ,bushy ,samphire4 ,further investigation is necessary to determine the exact relation of the different salts to the growth of the plant1 and as to whether carbonates occur in large quantity2 but enough data have been gathered to show that a luxuriant growth of ,suaeda torreyana indicates a soil reclaimable only by thorough-drainage4 ,suaeda torreyana occurs on low alkali lands throughout the ,state of ,california1 from ,san ,bernardino to ,honey ,lake1 in the desert sinks1 and in the ,great ,valley1 in appropriate locations4 ,sometimes it is replaced by ,s4 suffrutescens and perhaps other species1 but all the saltworts appear to grow in similar habitats1 and it is probable that the soil-conditions are practically the same for all these species4 ,they indicate land too heavily impregnated for the growth of ordinary crops1 but which will perhaps allow the ,australian saltbush to succeed4 ,illustration3 ,,fig4 #he4--,saltwort--,suaeda ,torreyana1 ,wats4 ,,greasewood 7,sarcobatus vermiculatus7 ,hook4 ,torr42 ,,fig4 #hf4 ,this1 the true ,greasewood of the desert region east of the ,sierra ,nevada1 and not either of the plants known under that name in the ,san ,joaquin ,valley and in ,southern ,california1 invariably indicates a heavy impregnation of the land with black alkali or carbonate of soda4 ,since1 as before stated1 black alkali is most likely to occur in low ground1 we frequently find the true greasewood forming bright green patches in the swales1 and on the benches of periodic streams1 as well as on the borders of alkali ponds or lakes4 ,stock unaccustomed to it will frequently go to these patches on a run1 only to turn away badly disappointed after taking a few bites1 the plant being both bitter and salty4 ,illustration3 ,,fig4 #hf4--;,greasewood 7proper7--,sarcobatus vermiculatus 7,hook7 ,torr4 ,a4 ,appearance of a branch when not in blossom4 ,b4 ,spiny-branchlet from the same4 ,c4 ,branchlet bearing cones of male flowers4 ,d4 ,cone of male flowers1 enlarged4 ,e4 ,branch bearing fruits4 ,f4 ,cluster of fruits1 enlarged4 ,g4 ,vertical section through a fruit1 showing the seed with its curved embryo1 7enlarged74 ,where a luxuriant growth of this plant is found1 the soil may contain from #ch1jjj to #aag1jjj pounds of total salts per acre1 of which sometimes nearly half is carbonate of soda2 the content of common salt is usually low1 and ,glauber's salt or sulfate of soda1 sometimes with considerable proportion of epsom salt1 forms a variable proportion of the total4 ,greasewood is distinctly a plant of the ,great ,basin1 only reaching ,california in the adjacent counties of ,lassen1 ,alpine1 ,mono1 and northern ,inyo4 ,it is very abundant on the lower levels of ,honey ,lake valley1 ,cal4 ,the ,sarcobatus is chiefly found on silty or sandy soils of good native fertility 7see page #dde1 chapter #bb71 so that when its excess of salsoda is neutralized by means of gypsum1 the land becomes very productive4 ,unfortunately the cost of the amount of gypsum required to render such soils adapted to the tolerance of most culture plants is often prohibitive2 but where the correction of only small spots is called for1 the 8white alkali0 resulting from the gypsum treatment would be tolerated by many culture plants4 ,,alkali-,,heath 7,frankenia grandifolia campestris ,gray72 ,fig4 #hg4 ,illustration3 ,,fig4 #hg4--;,alkali-,heath--,frankenia grandifolia campestris ,a4 ,gray4 ,alkali-heath is perhaps the most widely distributed of any of the ,california alkali plants4 ,its perennial1 deep-rooting habit of growth1 and flexible1 somewhat wiry rootstock1 which enables it to persist even in cultivated ground1 render it a valuable plant as an alkali indicator4 ,the salt-content where ,alkali-heath grows luxuriantly is invariably high1 ranging from #fd1jjj to #bhb1jjj pounds per acre2 salsoda varies from #fhj to #ai1eij pounds2 common salt ranges from #e1jjj to #aj1jjj pounds4 ,such soils would not be benefited by the application of gypsum1 as the salts are already largely in the neutral state4 ,of useful plants only ,saltbushes and ,tussock-grass are likely to flourish in such lands1 when not too wet4 ,while ,alkali-heath is thus one of the most alkali-tolerant plants1 it is at the same time capable of growth with a minimum of salts 7total salts #c1gjj pounds1 salsoda #fhj pounds74 ,where only a sparse growth of this plant occurs1 therefore1 the land should not be condemned until a chemical examination of the soil has been made4 ,alkali-heath is found on soils of very varying physical texture and degrees of moisture2 while on soils of uniform texture and moisture-conditions1 but differing in chemical composition1 it varies with the varying salt-content4 ,it has been found that ,australian saltbush 7,atriplex semibaccata7 can be successfully grown on the 8goose-lands10 of the ,sacramento ,valley1 on soil producing a medium crop of ,alkali-heath2 it remains to be shown whether it will do equally well on soils producing a dense and luxuriant growth of the same4 ,alkali-heath is widely distributed throughout the interior valleys of ,california2 a closely related form grows in the salt-marshes of the sea-coast4 ,,cressa 7,cressa cretica truxillensis ,choisy72 ,fig4 #hh4 ,cressa soils show a low percentage of the noxious salsoda1 but comparatively heavy total salts 7#afa1jjj to #bhb1jjj pounds per acre47 ,common salt varies from #e1gfj to #bj1hdj pounds per acre in four feet4 ,the maximum is lower than in the case of ,alkali-heath1 but ,cressa seems to be much more closely restricted to strong alkali than does the former species4 ,cressa appears to be as widely distributed through the interior valleys of ,california as ,alkali-heath4 ,the ,cressa is a cosmopolitan plant1 occurring1 as its name indicates1 on the ,ionian ,islands1 as well as in ,north ,africa1 ,syria1 and other arid countries of the world4 ,,saltgrass1 ,distichlis spicata4--,this grass is of world-wide distribution1 and always indicates a sensible content of soluble salts1 without apparently any special preference for either of the three most commonly occurring ones4 ,its maximum tolerance1 as will be seen by the preceding table1 is very high1 yet at the same time it will grow luxuriantly on lands containing so little that other saline plants like the samphires1 saltwort or greasewood will refuse to grow4 ,on the shores of ,honey ,lake1 ,california1 it may often be seen incrusted with the salts of the water concentrated by a long season of drought1 yet maintaining life1 though somewhat stunted4 ,on lands lightly impregnated1 stock will often eat it quite freely1 so that it has been mistaken for ,bermuda grass1 to which its habit and foliage bears some resemblance4 ,but ,bermuda grass1 while not as sensitive to alkali as most forage grasses1 will probably not bear much over #ab1jjj pounds per acre4 ,illustration3 ,,fig4 #hh4--;,cressa--,cressa cretica truxillensis1 ,choisy4 ,the mere presence of the salt grass cannot therefore be taken as a definite indication of anything more than that there is an unusual amount of salts in the soil2 whether or not there is more than will be tolerated by the ordinary culture-plants1 must be judged either from the accompanying plants1 or by experiment or analysis4 ,illustration3 ,,fig4 #hi4--,salt-,grass--,distichlis spicata 7,l47 ,greede4 ,relative ,tolerance of the ,different ,species4--,the following table shows in systematic order the tolerance of the several plants discussed above1 for the different salts1 so far as the data available permit4 ,the column marked optimum shows under what proportions of salts the plants grew in about equal luxuriance1 therefore under1 apparently1 the most favorable conditions4 ,both above and below the proportions mentioned in that column1 the luxuriance 7size7 and 7usually7 the abundance of the plants was less2 showing that while excessive amounts of salts depressed their welfare1 yet they also suffered when the proportions dropped below a certain point4 ,whether this was partly or wholly the result of competition with other plants1 is an unsettled question4 ,,table ,,showing ,,maximum1 ,,optimum1 ,,and ,,minimum ,,of ,,salts ,,tolerated ,,by ,,each ,,of ,,the ,,several ,,alkali ,,plants4 ---------------------------------------- -------------------- ,pounds ,per ,acre in feet4 --------------------------- ,optimum4 ,maximum4,minimum4 ---------------------------------------- ------------------ ,total ,salts4 ,bushy ,samphire #did1cbj #did1ebj #ace1jfj ,dwarf ,samphires #dda1hhj #dda1hhj #dda1hhj ,alkali-heath #bha1ifj #dii1jdj #c1gbj #fd1cjj ,cressa #bha1ifj #bha1ifj #afa1afj ,saltworts #acj1jjj #aec1jbj #c1gbj ,greasewood #eh1efj #eh1efj #b1djj ,tussock-grass #di1jjj #dii1jdj #di1jjj ,carbonate 7,salsoda74 ,tussock-grass #bc1jjj #dd1dfj #c1jdj ,alkali-heath #bjb #ai1eij #ai1eij #fhj #fhj ,greasewood #ah1gbj #ah1gbj #a1bhj ,dwarf ,samphires #ab1abj #ab1abj #b1bjj ,saltworts #aj1dhj #ab1abj #a1abj ,cressa #e1ddj #e1ddj #fhj ,bushy ,samphire #d1hjj #d1hjj #a1ejj ,chloride 7,common ,salt74 ,bushy ,samphire #bab1jhj #bge1afj #ef1hjj ,dwarf ,samphires #abe1fdj #abe1fdj #abe1fdj ,saltworts #ci1gfj #eb1ijj #a1jdj ,cressa #bj1hdj #bj1hdj #e1gfj ,alkali-heath #aj1ahj #bab1jhj #a1jdj #e1gfj ,tussock-grass #f1bjj #agb1hjj #c1ecj ,greasewood #c1fhj #c1fhj #afj ,sulphates 7,glauber's salt74 ,dwarf ,samphires #cad1jdj #cad1jdj #cad1jdj ,bushy ,samphire #bgg1fdj #bgg1fdj #ej1jhj ,cressa #bge1ebj #bge1ebj #acd1hhj ,alkali-heath #bge1ebj #cbc1bjj #a1efj #cd1ecj ,saltworts #dd1afj #ajd1jdj #a1efj ,greasewood #cf1afj #cf1afj #ifj ,tussock ,grass #ai1fdj #cbc1bjj #ai1fdj ---------------------------------------- ------------------ #bjb ,this plant grows with equal luxuriance in soils containing only #fhj pounds of carbonates4 ,,appendices4 ,,appendix ,a4 ,,directions ,,for ,,taking ,,soil ,,samples4 ,,issued ,,by ,,the ,,california ,,experiment ,,station4 ,in taking soil specimens for examination by the ,agricultural ,experiment ,station1 the following directions should be carefully observed2 always bearing in mind that the examination1 and especially the analysis1 of a soil is a long and tedious operation1 which cannot be indefinitely repeated4 ,first4--,do not take samples at random from any points on the land1 but consider what are the two or three chief varieties of soil which1 with their intermixtures1 make up the cultivable area1 and carefully sample these1 each separately2 then1 if necessary1 sample your particular soil1 noting its relation to these typical ones4 ,second4--,as a rule1 and whenever possible1 take specimens from spots that have not been cultivated1 nor are otherwise likely to have been changed from their original condition of 8virgin soils0--e4g41 not from ground frequently trodden over1 such as roadsides1 cattle-paths1 or small pastures1 squirrel holes1 stumps1 or even the foot of trees1 or spots that have been washed by rains or streams1 so as to have experienced a notable change1 and not be a fair representative of their kind4 ,third4--,observe and record carefully the normal vegetation1 trees1 herbs1 grass1 etc41 of the average virgin land2 avoid spots showing unusual growth1 whether in kind or in quality1 as such are likely to have received some animal manure1 or other outside addition4 ,fourth4--,always take specimens from more than one spot judged to be a fair representative of the soil intended to be examined1 as an additional guarantee of a fair average1 and mix thoroughly the earth taken from the same depths4 ,fifth4--,after selecting a proper spot1 pull up the plants growing on it1 and sweep off the surface with a broom or brush to remove half-decayed vegetable matter not forming part of the soil as yet4 ,dig or bore a vertical hole1 like a post-hole1 and note at what depth a change of tint occurs4 ,in the humid region1 or in humid lowlands of the arid1 this will usually happen at from six to nine inches from the surface1 and a sample taken to that depth will constitute the 8soil40 ,in ,california and the arid region generally1 very commonly no change of tint occurs within the first foot1 sometimes not for several feet2 hence1 especially in sandy lands1 the 8soil0 sample will usually be taken to that depth1 so as to represent the average of the first foot from the surface down4 ,samples taken merely from the surface1 or from the bottom of a hole1 have no definite meaning1 and will not be examined or reported upon4 ,place the 8soil0 sample upon a cloth 7jute bagging should not be used for the purpose1 as its fibres1 dust1 etc41 become intermixed with the soil7 or paper1 break it up1 mix thoroughly1 and put at least a quart of it in a sack or package properly labeled1 for examination4 ,this specimen will1 ordinarily1 constitute the 8soil40 ,should the change of color occur at a less depth than six inches1 the fact should be noted1 but the specimen taken to that depth nevertheless1 since it is the least to which rational culture can be supposed to reach4 ,in the same way take a sample of each foot separately to a depth of at least three feet2 preferably four or five1 especially in the case of alkali soils1 or suspected hardpan4 ,sixth4--,whatever lies beneath the line of change1 or below the minimum depth of six inches1 will constitute the 8subsoil40 ,but should the change of color occur at a greater depth than twelve inches1 the 8soil0 specimen should nevertheless be taken to the depth of twelve inches only1 which is the limit of ordinary tillage2 then another specimen from that depth down to the line of change1 and then the 8subsoil0 specimens beneath that line4 ,the depth down to which the last should be taken will depend on circumstances4 ,it is always necessary to know what constitutes the foundation of a soil1 down to the depth of three feet at least1 since the question of drainage1 resistance to drought1 root-penetration1 etc41 will depend essentially upon the nature of the substratum4 ,in the arid region1 where roots frequently penetrate to depths of ten or twelve feet or even more1 it is frequently necessary to at least probe the land to that depth or deeper4 ,the specimens should be taken in other respects precisely like that of the surface soil1 each to represent the average of not more than twelve inches4 ,those of the materials lying below the third foot from the surface may sometimes be taken at some ditch or other easily accessible point1 and if possible should not be broken up like the other specimens4 ,if there is hardpan or heavy clay present1 an unbroken lump of it should be sent1 for much depends on its character4 ,seventh4--,when in the case of cultivated lands1 it is desired to ascertain the cause of differences in the behavior or success of a crop on different portions of the same field or soil area1 do not send only the soil which bears unsatisfactory growth1 but also the one bearing normal1 good growth1 for comparison4 ,in all such cases1 try to ascertain by your own observations whether or not the fault is simply in the subsoil or substrata2 in which case a sample of surface soil sent for examination would be of little use4 ,in such examinations the soil probe will be of great service1 and save much digging or boring4 ,eighth4--,specimens of alkali or salty soils should preferably be taken towards the end of the dry season1 when the surface layers will contain the largest amount of salts4 ,a special sample of the first six inches should in that case be taken separately by means of a post-hole auger1 and then1 in a different spot close by1 a hole four feet deep should be bored1 and the earth from the entire four-foot column intimately mixed before the usual quart sample is taken4 ,samples of the plants growing on the land should in all cases be included in the package1 as they indicate very closely the agricultural character of the land4 ,all samples taken while the land is wet should be air-dried before sending2 in the case of alkali soils this is absolutely essential4 ,ninth4--,all peculiarities of the soil and subsoil1 their behavior under tillage and cultivation in various crops1 in wet and dry seasons1 their location1 position1 8lay10 every circumstance1 in fact1 that can throw any light on their agricultural qualities or peculiarities1 should be carefully noted1 and the notes sent by mail4 ,without such notes1 specimens cannot ordinarily be considered as justifying the amount of labor involved in their examination4 ,any fault found with the behavior of the land in cultivation or crop-bearing should be specially mentioned and described4 ,the conditions governing crop-production are so complex that even with the fullest information and the most careful work1 cases are found in which as yet the best experts will be at fault4 ,,appendix ,b4 ,,summary ,,directions ,,for ,,soil--,,examination ,,in ,,the ,,field ,,or ,,on ,,the ,,farm4 ,while the general principles upon which the cultural value and adaptations of lands should be judged1 have been given in the text of this volume1 it seems advisable to summarize their practical application to land examination here1 for convenient reference4 ,the directions given in ,appendix ,a for the sampling of soils having been carried out1 the samples so taken may be subjected to farther examination by any intelligent farmer to good purpose1 and often with great saving of time and expense4 ,spread the samples from the several depths in regular order upon a table or bench1 and note the differences in color and texture apparent to the eye or touch1 and whether they will or will not crush readily between the fingers1 wet and dry4 ,whatever the fingers can do1 can similarly be done by the harrow1 cultivator1 clod crusher or roller4 ,the tilling qualities of the surface soil and immediate subsoil are the first and most important matter to be ascertained2 including especially their behavior to water4 ,place some air-dried lumps in a shallow dish with a little water2 observe whether they take up the water quickly or slowly1 and whether in so doing the lumps fall to pieces or retain their form4 ,slow penetration1 and maintenance of form1 will at once indicate a soil somewhat refractory and difficult to till2 while if the water is taken up easily and the lump falls to pieces1 the land is easily cultivated and will absorb the rainfall and irrigation water readily4 ,the darkening of the tint on wetting will also give an approximate idea of its humus-content4 ,then take a wetted lump and work it between the fingers and on the palm of the hand1 until its 8stickiness0 or adhesiveness ceases to increase4 ,this 8hand test0 is of first importance and in skillful hands will largely supersede the need of elaborate mechanical analysis4 ,it will at once enable the operator to classify the soil as a light or heavy loam1 clay loam or clay soil2 it will show directly what will be the result of plowing the land when wet1 the liability to the formation of a plowsole1 and whether a single or a double team will generally be needed to cultivate it properly4 ,also whether stock can be allowed to pasture the land soon after rain4 ,comparison with the known land of neighbors will also thus become easy1 and in a measure the crops best adapted to the physical qualities of the soil1 subsoil and substrata1 taking into account their respective depths1 will at once be at least approximately determined4 ,the presence of coarse and fine sand in greater or less amounts will also be thus readily ascertained1 allowing estimates of the percolative properties2 the latter can1 of course1 be more practically tested in the field1 in the manner described in chapter #ac1 page #bdb4 ,a more definite estimate of the amount and kind of sand present in the soil materials can be obtained by washing the kneaded sample into a tumbler1 and allowing a thin stream of water to flow into it from a faucet while gently stirring the turbid water4 ,the clay1 together with the finest silts1 will thus be carried off over the rim of the glass1 and sand of any desired degree of fineness1 according to the strength of the stream of water used1 will be left behind4 ,the kind and amount of these sandy materials can then be estimated1 or definitely ascertained by weighing or measuring4 ,this will1 generally speaking1 be as far as the uninstructed farmer can readily go2 but these simple operations will give him an insight into the nature of his soil and subsoil that will enable him to avoid a great many costly mistakes4 ,,recognition ,,and ,,meaning ,,of ,,the ,,several ,,soil ,,minerals4#bjc ,those somewhat familiar with scientific methods and operations1 and supplied with pocket lens or microscope1 can profitably go much farther towards the definite ascertainment of the permanent cultural value of the land1 by the study of the minerals of which the sand is composed1 and which as a rule represent those from which the entire soil has been formed2 therefore indicate in a general manner its chemical composition4 ,such examinations are specially feasible and important when soils are not far removed from their parent rocks1 as in most of the arid region1 and in the states north of the ,ohio4 ,in the ,southwestern states1 in the coastal plain of the ,gulf of ,mexico1 the original soil minerals have usually been too far decomposed to admit of definite identification4 ,sand is there as a rule made up of quartz grains of many varieties1 with only an occasional tourmaline and pyroxene4 #bjc ,for more details see chapters #c and #d4 ,among the prominent soil minerals1 quartz is almost always recognizable by its glassy luster and the irregular fracture--absence of definite planes or facets of cleavage1 causing the grains to be abraded or rounded nearly alike in all directions4 ,the feldspars1 on the contrary1 always show a tendency to cleave into fragments having definite1 obviously oblique angles1 which are perceptible even when the grains are somewhat worn2 because of the difference in the ease with which wear takes place in the several directions4 ,potash feldspar1 moreover1 which is the most important to be recognized because it indicates a relatively large supply of potash in the natural soil1 is but rarely glassy in luster1 but mostly dull white1 or reddish-white4--,the lime and lime-soda feldspars rarely show as definite forms1 because of their tendency to form complex crystalline aggregates 7twins73 and their definite recognition requires somewhat complex 7polarizing7 appliances in connection with the microscope4 ,in such cases1 however1 the accompanying minerals 7hornblende1 pyroxene1 mica and others7 often afford valuable indications1 because of their known association with soda-lime feldspars in certain rocks4 ,an abundant occurrence of hornblende fragments1 characterized by their flat1 tabular form1 and bottle-green or black tint1 indicate1 almost always a fairly good supply of lime in the soil1 but leaves the potash-supply in doubt4 ,pyroxene 7distinguished by its smooth1 polished surface from the angularly-weathering1 usually rusty hornblende fragments7 rarely occurs with potash feldspar2 and soils strongly charged with it are mostly poor in potash4 ,mica occurs in so many rocks and is of so little consequence as a soil-ingredient from the chemical point of view1 because of its difficult decomposition1 that its presence can mostly only serve to corroborate or contradict conclusions as to the derivation of a soil from some particular rock or region4 ,but mica serves a good purpose in improving the tilling qualities of soils4 ,its thin scales must not be mistaken for the tabular fragments of hornblende4 ,calcite in its several forms is mostly easily recognized both by its form under the microscope1 and by the effervescence its granules show when touched with an acid4 ,this effervescence can generally be observed on touching the wetted soil with chlorhydric acid1 so soon as the content exceeds two per cent2 but something depends upon the size of the grains1 as when these are very small1 the giving-off of gas is less readily noted4 ,to facilitate it1 the wetted soil may be warmed before touching it with the acid4 ,the recognition of the presence of lime carbonate in soils is so important as to justify considerable trouble in rendering it definite4 ,when the aid of a chemist cannot be commanded1 fairly definite conclusions may be drawn from the character of the native vegetation2 regarding which1 detailed information may be found in ,parts ,,iii and ,,iv of this volume4 ,but where1 as in the arid region1 this criterion is not available1 since the controlling factor there is the moisture supply1 a presumption may be gained by the application of a slip of moistened red litmus paper to the wetted soil4 ,should the red paper be turned blue within one or two minutes it would indicate the presence of carbonate of soda 78black alkali07 as well as of lime carbonates3 but if blued only after twenty minutes or more1 it would indicate the presence of the carbonates of lime and magnesia4 ,if not changed at all1 the conclusion would be that either lime carbonate is in very small supply1 or that the soil is in an acid condition4 7,see chapter #h1 p4 #abb74 ,saline and ,alkali ,soils4--,the presence of an unusual or injurious amount of soluble salts1 as in the case of sea-coast and alkali soils1 is commonly easily ascertained in the field2 where1 if the surface soil is at all seriously contaminated with soluble salts of any kind1 these may be seen on the surface during a dry season1 forming a whitish efflorescence1 which in most cases is definitely crystalline4 ,in doubtful cases a tablespoonful of the surface soil may be leached with water1 and the first ten or fifteen drops caught in a clean1 bright silver spoon and evaporated4 ,or the soil may be stirred up with about twice its bulk of water and the mixture be allowed to clear by settling1 then evaporating4 ,a slight whitish film will almost always remain in the spoon2 but if the amount be somewhat considerable1 the presence of soluble salts is very readily recognized by pouring a few drops of clear water on one side of the spot1 and then allowing it to flow gently over the spot to another place1 where it is again slowly evaporated4 ,any considerable amount of salts present will be shown both in the diminution of the original spot1 and in the soluble residue accumulated where the water was last evaporated4 ,should common salt be present to any considerable extent1 the residue in the silver spoon will1 if the last drops be allowed to evaporate slowly1 show square or cubical crystals to the naked eye1 and certainly to a common pocket lens4 ,the residue may also be tested with red litmus paper for carbonate of soda1 which would quickly turn it blue4 ,more detailed examination requires chemical reagents and experience1 but the above tests should be sufficient to prevent the mistaking of mere white spots1 whose humus has been destroyed by fermentation caused by bad drainage1 with true alkali caused by excess of soluble salts2 a mistake not uncommon in both the arid and humid regions4 ,,appendix ,c4 ,,short ,,approximate ,,methods ,,of ,,soil ,,examination ,,used ,,at ,,the ,,california ,,experiment ,,station4 ,,by ,r4 ,h4 ,,loughridge4 ,the ,california ,experiment ,station has for many years given the farmers of the ,state the privilege of having their soils examined to ascertain any physical defects1 deficiency in plant-food1 or the presence of alkali salts4 ,they have quite generally taken advantage of this1 and the number of samples of soil sent in each year has been very large4 ,a complete analysis of a soil-sample requires fully #ae days2 hence the necessity of adopting some quick methods for the determination of the main elements of fertility1 viz41 humus1 lime1 potash1 and phosphoric acid1 that would at the same time give results sufficiently accurate for practical purposes4 ,similarly for alkali salts in the soil2 the leaching-out and analysis of which often occupies more than a week4 ,the following methods have been adopted1 which shorten the time of examination for the plant-food of a soil to about one hour1 except for potash1 which requires a much longer time4 ,for alkali salts the time is reduced to two days1 and less if a pressure filter be used4 ,humus4--,the ,grandeau method of ammonia extraction requires the removal of the lime and magnesia with weak hydrochloric acid1 washing out of the acid and then digestion with weak ammonia2 all of which1 with a soil rich in humus1 may require many days1 though a number of samples may be put through at the same time4 ,the method adopted to determine adequacy or inadequacy of the humus 7for this is all that is intended in this examination7 is completed in less than half an hour4 ,it is based on the color of the humus-extract and avoids the necessity of removal of the lime from the soil4 ,the soil is pulverized in a mortar with a rubber pestle1 and passed through a half-millimeter sieve4 ,seven grams of the fine earth is placed in a test tube with #ae or #bj cc4 of a ten per cent solution of caustic potash and boiled for ten or fifteen seconds1 then allowed to settle4 ,the humus is dissolved and the density of the color of the solution is an indication of adequacy or inadequacy4 ,a dense black1 non-translucent solution shows the presence of at least one per cent of humus in the soil2 a deep brown translucent color indicates about one-half of one per cent2 while a light brown color clearly shows a deficiency in the soil1 and a need of a good green-manure crop4 ,lime4--,two grams of fine earth is treated with a little hydrochloric acid1 boiled for a few seconds1 and ammonia is added to precipitate the iron and alumina2 the whole1 with the soil-residue1 is quickly thrown on a filter to separate the mass from the lime solution1 and washed4 ,after adding ammonium chlorid the lime is precipitated with oxalate of ammonia1 and its adequacy for soil-fertility judged of by the turbidity of the solution1 or the bulk of the precipitate4 ,or the latter may be filtered off1 dried and weighed4 ,we thus obtain a measure of the carbonate and humate of lime present1 by comparing it with the precipitate obtained from a soil whose percentage of lime has been correctly ascertained4 ,potash4--,the determination of potash in the soils requires more time than either of the other ingredients1 and is more rarely made by us4 ,our knowledge of the soils of the ,state of ,california obtained through many analyses1 gives us a clue to those localities where potash would probably be deficient1 as well as to those whose soils are generally extremely rich in potash2 the percentages reaching usually from 4#e to as much as #a4e per cent and more4 ,for the determination1 two grams of the fine earth is digested in hydrochloric acid over a steam bath for two days1 the insoluble residue filtered off1 the filtrate evaporated to dryness to render the silica insoluble1 again filtered and the iron2 alumina and lime removed by precipitation with ammonia and oxalate of ammonia and filtration4 ,the filtrate is then evaporated to dryness1 the ammonia salts destroyed with aqua regia or driven off by heat1 and the alkalies changed to chlorids4 ,any residue is then filtered off and platin-chlorid added to precipitate the potash1 which is separated and determined in the usual way1 either by reduction of the platinum by ignition1 or by measurement in a ,plattner's potash tube4 ,phosphoric ,acid4--,the determination of phosphoric acid is based on the volume of the phospho-molybdate precipitate in a tube made like a ,plattner's potash tube1 but having a wider interior diameter for the smaller portion 7not greater than #c millimeters71 and a length of #ej mm4 ,with this diameter1 one mm4 in height of the precipitate obtained by our short method indicates one one-hundredth of one per cent of phosphoric acid in the soil4 ,the unit of measure must be obtained for each tube1 unless of uniform diameter1 and is ascertained by taking a soil whose phosphoric-acid percentage has been determined gravimetrically and giving it the following quick treatment2 which must1 of course1 be closely followed in each soil to be examined4 ,two grams of the fine earth is ignited in a platinum dish to destroy the organic matter1 transferred to a test-tube containing #e cc4 of nitric acid and made to boil for only a couple of seconds1 thus preventing the solution of silicates to any material extent4 ,it is not allowed to stand1 but a little water is immediately added and it is quickly thrown on a small filter and washed with a little water4 ,the phosphoric acid is then precipitated with molybdic acid at the proper temperature2 allowing it to settle1 the liquid is drawn off and the precipitate transferred to the measuring-tube4 ,it settles into the small part in a short time if the latter is not too narrow1 and is then measured with a millimeter scale4 ,this represents the percentage as found in the soil by the gravimetric method1 and serves as a guide for other examinations1 whose agreement with gravimetric determinations is generally quite close1 and quite sufficient for practical purposes4 ,the rapidity with which the solution is made and separated from the soil is a matter of special importance for comparative results1 or determination of percentages2 for if the acid solution be allowed to stand for some time before filtration from the soil1 silica passes into solution also1 and the volume of the molybdate precipitate is increased by it2 thus vitiating the results and adding to the time required for the method4 ,by this short method the practically important phosphoric acid in the soil may be approximately determined within half an hour4 ,,short ,,method ,,for ,,alkali ,,salts4 ,the old method of obtaining solutions of the salts by leaching the soil on a filter until all of the alkali had been washed out has been replaced by the following short one4 #ej or #ajj grams of the well-mixed soil is placed in a bottle containing #bjj cc4 of water1 shaken up occasionally during #ab hours and allowed to settle4 ,the solution may then be passed through a common filter 7or preferably a pressure filter7 and an aliquot part 7usually #ej cc47 of the filtrate evaporated to dryness in a platinum basin and ignited at a temperature just below redness to destroy any organic matter that may be present4 ,the basin and contents are weighed and the soluble salts are dissolved in a very little water and separated by filtration through a small filter into a #ej cc4 cylinder and the alkali carbonates and chlorids determined by titration1 being calculated as sodium compounds4 ,the material remaining on the filter and in the basin1 consisting of insoluble earth1 carbonates and calcium sulfate1 is gently ignited in the basin and weighed2 the difference between this and the first weight gives approximately the total soluble salts1 which should substantially correspond to the titrations made4 ,the sulfates are determined by differences between these and the total alkalies4 ,the solution may contain some sulfate of magnesia1 or calcium and magnesium chlorids1 and these are determined gravimetrically4 ,nitrates1 which may have been destroyed in the first ignition1 are determined in the original solution by the picric method4 ,any magnesia rendered insoluble by the ignition may usually be accounted for as chlorid1 unless much nitrate is present which is rarely the case in carbonated alkali4 ,if much nitric acid was found1 it should be first assigned to magnesia4 ,,index4 ,a4 ,,page ,absorption and movements of water in soils1 #bba of solids from solutions1 #bfg of gases by soils1 #bgb1 #bge ,acacias1 tolerance of alkali1 #dhj ,accessory minerals1 #ej ,acid1 strength used in soil analysis1 #cda ,acidic and basic eruptive and metamorphic rocks1 #di ,acidity1 neutrality1 alkalinity of soils1 #cbb ,acids of different strengths1 analysis with2 table1 #cbf1 #cda ,action of plants in soil formation1 mechanical and chemical1 #ai ,aeration and reduction as influencing nitrification1 #adg effects of insufficient1 in soils1 #bhj excessive1 injury in arid regions1 #bhj ,aerobic and anerobic bacteria1 #add ,air1 functions in soils1 #bgi 8 of soils1 composition of1 #bhj ,air-space in soils2 figure1 #ajh ,alabama1 vegetation and soil-characters1 #eaa ,alaska current1 effects on ,california climate1 #bif ,alinit1 #adi ,alkali carbonates and sulfates1 inverse ratio1 #dea1 #deb carbonates1 effects on clay1 #fb effects on culture plants2 figure1 #dbf1 #dbg ,alkali-heath1 range1 tolerance of alkali1 figure1 #edd1 #ede ,alkali lands1 crops for strong1 #dfh effects of irrigation on1 #dbh efficacy of shading1 #deg exceptionally productive when reclaimed1 #dhc fertilization not needed in1 #dhc formation from leachings of slopes1 #dec geographical distribution of1 #dbc high and lasting production when reclaimed1 #dhb inducements toward reclamation of1 #dha in the ,san ,joaquin valley1 ,cal41 figure1 #dbe possible injury to1 from excessive leaching1 #dfb ,alkali lands1 summary of conclusions1 #dec surface and substrata of1 #dbi utilization and reclamation of1 #dee of world-wide importance1 #dbd vegetation of1 #ecd ,alkali-resistant crops1 #dee ,alkali salts1 black and white1 #dda composition of1 #dci composition of2 general table1 #ddb1 #ddc distribution in heavy lands1 #dcf1 #dcg effects on beet crop1 #dfe horizontal distribution of1 #dci in hill lands1 #dci in sandy lands1 #dcc1 #dce in ,salton ,basin1 distribution of1 #d1 #cf1 #dch leaching-down of1 #dei nature of1 #dbc plant food in1 #dda1 #ddd reactions between1 #ddi1 #dej reduction by cropping1 #dfc relative injuriousness of1 #dfd removal from the soil1 #deh removal by deep-furrow irrigation2 figure1 #dfj1 #dfa tolerance of various crop plants2 table1 #dff1 #dfg total in lands2 estimation of1 #ddd underdrainage the universal remedy for1 #dfj upward translocation from irrigation1 #dcc vertical distribution in soils1 #dbi1 #dca1 #dcb1 #dcd ,alkali soils and seashore lands1 #dbb calcareous character of1 #bh composition of1 as a whole1 #dde1 #ddf1 #ddg how native plants live in1 #dcj origin of1 #dbb repellent aspect1 cause of1 #dbd retention of silica in1 #cib ,alkali spots1 white1 #bhf ,alkali1 rise of1 #dbh turning under of surface1 #def weeds as cattle food1 #dfh study of1 by ,loughridge and ,davy1 #ece ,aluminic hydrate1 in soils of ,california and ,mississippi2 table #aja1 #cij ,alluvial soils1 #ab ,ammonia-forming bacteria1 #adi ,ammonia gas1 absorption of1 by soils2 figure1 #bgd1 #bge ,ammonic carbonate1 effects on glass1 #ah ,ancient civilizations1 preference for arid countries1 #dag rare in humid countries1 #dah ,apatite1 #fc ,arid and humid climates1 rock-weathering in1 #dg ,arid and humid regions1 criteria of soils of1 #cga contrast between soils of1 #bh soils of1 #aaa1 #cga ,arid and humid soils1 general comparison2 table1 #cge1 #cgg ,arid belts1 subtropic1 #bih1 #bii utilization of1 #bii ,arid conditions1 local1 in tropical countries1 #dja ,aridity1 influence upon civilization1 #dag ,arid region1 bunch grasses on soils of1 #aaa standing hay in1 #cjj upland soils of2 table1 #cgc1 #cgd ,arid soils1 productiveness induces permanent civil organization1 #dab ,arroyo ,grande and ,yazoo buckshot soils1 #cde ,asparagus1 resistant to salts1 #dge ,atmosphere1 composition of2 table1 #af ,azotobacter1 #aef ,lipman on1 #aef ,b4 ,bacteria1 active in soil-formation1 #bj aerobic and anaerobic1 #add denitrifying1 #adh food and functions of1 #ade in soils1 numbers of1 #adb micro-organisms of soils1 #adb multiplication of1 #add nitrifying1 #adf ,bacterial life1 effect on soil1 condition1 #adi relation of carbonic dioxid to1 #bha ,bacteroids1 #aea ,mork figures1 #aeb1 #aec ,basaltic rocks1 #di ,basalts1 red soils from1 #eb ,basic slag1 #fd ,basin irrigation1 advantages of1 #bdc ,bauxite in soils1 #aja1 #cij ,beet1 sugar1 effects of salts on1 #dgd tolerant of common salt1 #dgd ,bhil soils1 #dad ,bicarbonate of soda1 #gh ,black-alkali lands1 difficulty in draining1 #dfb neutralizing of1 #deg waters1 use of1 #bej why so called1 #gh ,black earth of ,russia1 humus in2 table1 #acj ,black sand1 #de ,black prairie soils1 #ec ,black soils and lands1 #bhc ,blizzards in continental ,america1 #bih ,blown-out lands1 #i ,blue tint in clays and subsoils1 #de ,bodengare1 #adi1 #aej1 #bha ,bog ore1 formation of1 in subsoils1 #df1 #ff ,bones1 composition of1 #fd ,bone meal1 efficacy of1 #fe ,borax1 borate of soda1 #gi ,bottom water1 #bbg rise of1 from irrigation1 #bbg1 #bcj ,bottoms1 first and second1 contrast between1 #ejf1 #ejg1 #eji ,bottoms1 first1 tree growth of1 #ejg1 #eji ,brahmaputra alluvium1 ,assam1 #dac ,brown iron ore1 #dd 8,buckshot0 soils of ,yazoo bottom1 #aaf 8,bunch grasses0 as alkali-resistants1 #dga ,burning-out of humus1 effects of1 #aah ,burrowing animals1 work in soil-formation1 #afj ,c4 ,calcareous clay1 crumbling on drying1 #aaf formations1 predominance in ,europe1 #ebe soils1 definition of1 #cfg1 #dif1 #ebd solubility of alumina and silica in1 #chi subsoils1 and hardpans1 #afb ,calciphile1 calcifuge and silicophile plants1 #eba ,calcite1 calcareous spar1 #ci recognition of1 #ci ,caliche1 in ,chile1 ,nevada1 and ,california1 #ff1 #fg ,capillarity1 #ahi ,capillary water1 reserve of1 #bbi rise of1 #bjb to #bjg ,carbonated water1 action on feldspar1 #cb action on silicates1 #ah universal solvent1 #ag ,carbonate of soda1 #gg injury to soils and plants1 #gh ,carbonates1 chlorids and sulfates of earths and alkalies1 reactions between1 #ddi1 #dej ,carbonic acid1 #ag secreted by roots1 #bj ,carbonic dioxid1 absorption of1 by soils1 #bgd heavily absorbed by ferric and aluminic hydrates1 #bgh occurrence1 formation1 #ag relation to fungous activity1 #bha ,cascade range1 climatic divide in ,n4 ,w4 ,america1 #big ,caves in limestone regions1 #da ,celery1 moderate tolerance of alkali1 #dge ,centrifugal elutriator1 ,yoder's1 #ib ,cereals1 alkali-resistance1 barley1 gluten wheats1 #dga ,channels1 cutting-out by gravel1 #f ,charcoal1 absorption of gases by1 #bgf1 #bgg ,chemical absorption by soils1 #bgj action of roots1 #bj analysis of soils 7in general71 #cbc character of soil1 recognition of1 #cbb decomposition1 causes intensifying1 #ba processes of soil formation1 #af ,chile saltpeter1 #ff ,chernozem1 #acj analyses of1 table1 #cfd ,chestnut1 ,american1 a calcifuge tree1 #dia1 #eai ,chlorin1 largest ingredient of sea water1 #bg ,chlorite1 #cf ,chlorosis of vines in marly lands1 #ebf ,churn elutriator1 ,hilgard's2 figure1 #ia ,circling of hill lands1 #bbj ,citrus fruits1 injury to1 from alkali1 #dgh lemons most sensitive1 #dgh sensitiveness to common salt1 #dgg ,classification of rocks1 #dg of soils1 #aj ,clay as a soil ingredient1 #hc colloidal1 #ei functions of1 in soils1 #ei maintains crumb structure1 #aaj ,clays1 claystones1 clay shales1 #dh colors of1 #eh formation1 flocculation and deposition of1 #cc maturing of1 #fj plasticity and adhesiveness1 influence of fine powders on1 #he influence of ferric hydrate on1 #he ,clay-sandstones1 soils from1 #eg ,clays1 separation of1 by subsidence1 by centrifuge1 #hi varieties1 enumeration of1 and characters1 #eg1 #eh fusibility of1 #eh ,claystones1 soils from1 #ei ,cleavage of rocks1 #c ,cleopatra's needle1 #b ,climate1 #bhg ,climatic and seasonal conditions1 #ba ,climates1 continental1 coast and insular1 #big ,coffee soils1 calcareous1 #dag ,colloidal clay1 amount in soils4 ,table1 #hd analysis of1 by ,loughridge1 #che effects of alkali carbonates upon1 #fb investigation by ,schloesing1 #ei properties of1 #fa separation of1 by boiling and kneading1 #fa ,colloid humates1 #acc ,colluvial soils1 #ab ,colors of soils1 advantages of1 #bhc ,common salt1 injuriousness in soils1 #gf recognition of1 #gf removal from soils1 #gf ,conglomerates1 #dh ,conifers1 tall growth of1 in arid regions1 #eag ,contraction of soils in wetting and drying1 #aad ,co-operation1 favored by need of irrigation1 #dai ,corsican and maritime pine1 ash analyses1 #ebj ,cotton1 compact growth and heavy boiling on calcareous soils1 #ejc ,cracking of clay soils in drying1 #aac ,cressa2 range1 tolerance of alkali1 figure1 #ede1 #edf ,creep1 #ab ,crops1 alkali-resistant1 #dee ,crumbling of calcareous clays on drying1 #aaf ,crumb-structure of soils2 figure1 #aaj ,crusting of soils1 effects of1 #aaa1 #aag1 #bba ,cultivated soils1 analysis of1 #cbe investigation of1 #caf ,cultural experience the final test1 #cbd ,cutting-out of channels by water-borne gravel1 #f ,cypress1 different forms of2 figures1 #ejg1 #ejh ,d4 ,date palm1 resistance to alkali1 #dgh ,decomposition1 chemical1 of rocks1 #af ,decolorizing action1 of soils1 charcoal1 #bfg ,deep-rooting of native plants in arid region1 #agd ,deforestation1 effects of1 #bai ,deltas1 formation of1 #g ,denitrifying bacteria1 #adh ,deserts1 effects of winds in1 #h ,desert sands1 only lack water to become productive1 #dbj ,dew1 formation of1 #cjg rarely adds moisture to soils1 #cjh within the soil1 #cjh ,differentiation of soil and subsoil1 causes of1 #aba ,distance between furrows and ditches1 #bda ,dolomite1 #db ,drainage1 rights-of-way for1 #dfa ,drainage waters1 use for irrigation1 #bej ,drain waters1 analyses of1 table1 #bb leaching effects of1 #bga ,drouth1 resistance to1 in arid soils1 #afg ,dust soils1 nature of1 #ajd slow penetration of water in1 #aje ,dust storms1 #i ,dynamite1 used for shattering dense substrata1 #aha ,e4 ,earth's crust1 known thickness1 xxiv ,earthworms1 action of in soil-formation1 #aeh ,ecological studies1 #cad ,egypt1 obelisks of1 #b ,elements constituting earth's crust1 table of1 xxiv important to agriculture1 list of1 xxiv ,elutriator1 ,hilgard's1 figure1 #ia ,epsomite1 epsom salt1 in soil1 #gh ,eremacausis1 #abi ,erosion in arid regions1 #bai in ,mississippi table lands2 figures1 #bah lowering of land by1 #ae of rocks by sand2 figure1 #aj ,eruptive rocks1 basic and acidic1 #di rocks1 soils from1 #eb ,eucalyptus1 tolerance of alkali1 #dhj ,european observations on plant distribution1 #eai standards of plant-food adequacy--,maercker's table1 #cfi ,europe1 predominance of calcareous formations in1 #ebe ,evaporation and crop yields1 calculated1 #aic and crop yields1 observed 7,fortier71 #aid and plant growth1 #aic counteracting1 in alkali lands1 #dee dependence on air temperature2 ,fortier's experiments1 table1 #bee from reservoirs and ditches1 #beg from water surfaces1 #bed wet and moist soils1 #bed in different climates1 #aib1 #bef in different localities1 ,california1 #bee restrained by loose surface layer1 #bee through roots and leaves1 amount of1 #bfb1 #bfc ,expansion by oxidation1 #ah ,f4 ,farmyard or stable manure1 #gb ,feldspars1 weathering of1 #ca products of1 #cb ,ferghana1 alkali lands in1 #dda ,ferric hydrate1 effects of1 #ajj functions of1 in soils1 #bhe high absorptive power of1 #bgg in ,hawaiian soils2 table1 #cef more diffused in humid than in arid soils1 #cib ,ferric phosphate1 unavailability of1 #cef ,ferroso-ferric hydrate and oxid1 #ah1 #de ,ferrous oxid1 #ah ,ferruginous lands1 injury from swamping of1 #bcc ,fertilizers1 mineral1 #fc waste of1 by leaching1 #bfi ,flocculation and floccules1 #ia ,flocculated structure2 cements maintaining1 #aaj1 #aaa ,flood-plains of rivers1 #ad1 #ae ,fool's gold1 #ge ,force exerted by roots1 #ai ,forecasts1 general1 of soil quality in forest lands1 #ejg of soil values1 popular1 #cac ,forest trees1 forms of1 #dii to #ejb of ,atlantic states on alkali lands1 #dha ,form and development of trees1 differences in1 #dih ,forms of leaves1 variation in1 #ejb black-jack oak1 #dii1 #eja post oak1 #dii1 #ejj trees1 deciduous1 in arid region1 #eaf willow1 scarlet1 black and ,spanish oaks1 #ejb ,freezing water1 effects of1 #c ,frost1 effect of soils1 #aah ,fruiting1 favored by lime in soils1 #ejc ,fungi and molds1 action of1 #abc functions in humus-formation1 #aeg ,g4 ,gases1 absorption of1 by soils1 #bgb1 #bge partial pressure of1 #bgf ,germination of seeds1 #cji ,glacier flour1 fineness and fertility of1 #e physical analysis of1 #e ,glaciers1 grinding and abrasion by2 figure1 #c ,glauber's salt1 #gg ,glauconite1 in calcareous sandstones1 #ef ,gneiss soils1 #ea ,gobi desert1 migration of lakes1 #i ,going-back of orchards1 #ahb ,grain-sizes1 effect on percolation2 table1 #bbd influence on soil texture1 #ajj ,grandeau method of humus estimation1 #acb ,granite soils1 potash and phosphoric acid in1 #ej ,granitic rocks1 weathering of1 #dg sand1 formation in arid climates1 #b ,grano-diorite soils1 of ,sierra ,nevada1 #ea ,granular sediments1 influence upon tilling qualities1 #ajb ,grape-vine1 alkali1 tolerance of1 #dge ,grasses1 cultivated1 sensitive to alkali1 #dga ,greasewood1 range1 tolerance of alkali2 figure1 #edb1 #edc ,greenstones1 soils from1 #ea ,ground water1 depth most favorable to crops1 #bbh variation of surface of1 #bbh ,gulf-stream1 #bie ,gypsum or selenite1 formation from sea-water evaporation1 #db how recognized1 #db ,h4 ,halite1 #gf ,hardpans1 causes1 formation and cements of1 #ahe ,hardpan1 physical1 analysis of1 #ajc plowsole1 #bda ,hawaiian ,islands1 humid and arid sides of1 #big soils1 analyses of1 #cef ,hay bacillus2 figure1 #adi1 #aej ,heat and cold1 effects on rocks1 #a of high and low intensity1 #cjd reflection and dispersion from soil surface1 #cjd relations to soils and plant growth1 #cja trapping of suns1 #bhh ,heaviest clay soils1 physical analysis of1 #aae ,heaving-out of grain1 #aai ,hematite1 #dd ,herbaceous plants as soil indicators1 #eag ,hog-wallows1 #aad ,hornblende and pyroxene1 #cc weathering of1 #cc ,horsetail rushes1 secretion of silica by1 #ca ,humates and ulmates1 #acc cementing effects of1 #aaa ,humid and arid climates1 rock-weathering in1 #dg ,humid region1 upland soils of2 table1 #cgb1 #cgd ,humification in soils1 #bj normal conditions of1 #abi tests2 ,snyder1 tables1 #adj ,humin substances1 formation of1 #abc ,humus1 amidic constitution of1 #abe and coal1 amounts of1 from vegetable substance1 #abh amount in soils1 #acc ash of1 from ,minnesota soils1 analysis1 #acd decrease of nitrogen-content with depth1 #ace determination in soils1 #acb distribution in the surface soil1 #aeg functions in soils1 #ba in arid and humid regions1 #ach in black earth of ,russia1 #acj in ,minnesota soils1 #aca in ,north ,dakota soils1 #acc in the surface soil1 #abj losses from cultivation and fallow1 #aca nitrogen of1 #abd1 #ace percentage in soils1 and nitrogen-content of1 tables1 #ace1 #acf1 #acg porosity of1 #abd progressive changes in soils1 #abf relation to bacterial content1 #add scanty in arid soils1 but rich in nitrogen1 #cig substances1 physical and chemical nature of1 #abd variation of1 with original materials1 #aci volume weight of1 table1 #abe versus adipocere1 #adj ,hydraulic elutriation1 #ij ,hydromica1 #ce ,hydrous silicates in soils of arid region1 #chh ,i4 ,ice-flowers on soils1 #aai ,immediate plant-food requirements1 ascertainment of1 #ccc productiveness1 chemical tests of1 #ccg productiveness vs4 permanent value of soils1 #cah1 #cbg ,india1 climatic contrasts1 #dja ,indian soils1 table of analyses1 #daj #dab types of soils1 #daa ,indo-,gangetic plain2 calcareous hardpan1 kankar1 #daa ,injury from excessive runoff1 prevention of1 #bbj to plants from the various salts1 #eca to soils and plants from carbonate of soda1 #gh ,insects1 work in soil-formation1 #afj ,insoluble residue of soils2 less in arid than humid1 #chd ,insufficient rainfall1 leaves sea salts in soils1 #bh ,insular climate1 of ,britain1 western ,europe1 #bih ,introduction1 xxiii ,injury from swamping1 permanent1 #bcb ,iron carbonate solution1 how formed1 #dd coloring clays1 #eh minerals1 #dd pyrite1 how recognized1 #ge ,irrigation1 basin1 advantages and disadvantages1 #bdd by check flooding1 #bcg flooding1 #bcg furrows1 #bch lateral seepage1 #bdb1 #bda shallow1 deep and wide furrows2 diagram1 #bci surface sprinkling1 #bcg underground pipes1 #bde ditches1 leaky1 effects on alkali lands1 #dbi excessive surface rooting caused by1 #bde methods of1 #bcf necessitates co-operation1 #dai ,irrigation water1 abundant use of saline1 #bdi duty of1 #bea economy in use of1 #bdc effects of saline1 figures1 #bdg heavy losses in using1 #beb limits of salinity1 #bdf1 #bdh loss by evaporation1 #beb loss by percolation2 diagram1 #bec quality of1 #bdf saline1 how to use1 #bdi testing penetration of1 #bdb temperature of1 #bdd ,irrigation1 winter1 advantages of1 #bcf ,isinglass1 #dc ,j4 ,janesville loam1 chemical analysis of1 #cca ,japan current1 #bif ,jasper and hornstone pebbles1 weathering of1 #cj ,k4 ,kainit1 composition of1 #ga ,kaolinite and clay2 kaolin1 #cb assumes plasticity on trituration with water1 #fj crystalline form of1 #bb1 #ei lacks plasticity1 #fj ,kaolinization1 results in zeolite-formation1 #cie slow in arid regions1 #hg1 #chf ,l4 ,landholding1 units of1 smaller in arid than in humid region1 #dbj ,landlocked lakes1 water of1 #bg ,land plaster as a fertilizer2 effects on soils1 #dc ,landslides1 #ab ,laterite soils1 ,wohltmann's definition1 #daf ,terra roxa of ,brazil1 #daf ,leaching of the land1 #bb ,legumes1 bacteria of1 #aej mostly sensitive to alkali1 #dgb ,leguminous plants1 mostly calciphile2 exceptions1 #eah ,leucite1 potash content1 #cb ,lichens1 action on rock-surfaces1 #ai1 #bj ,lignites and coal1 how formed1 #abg ,lime a dominant factor in productiveness1 #cec ,lime carbonate in sea water1 #bf1 #bg removed from earth's surface1 #da summary of effects in soils1 #cgi ,lime-content1 effects of high1 in soils1 #cfe effects on availability of phosophates1 table1 #cff 8,lime-country is a rich country01 #cfe ,lime1 excess of1 in arid soils1 #cgh ,lime feldspars1 leave lime carbonate in soils1 #cb in alkali lands protects plants from salts1 #ecb lands1 failure of tea on1 #dad ,lime-loving trees1 #dij to #dib1 #dig ,lime1 most abundantly leached out1 #bd percentages1 what are adequate1 #cfg in coast-belt soils1 #dif1 #dig in heavy clay soils2 table1 #cfh ,lime renders lower amounts of plant-food adequate1 #ced ,limestone countries1 #ec ,rotten1 #ed soils1 excluded from comparison of arid and humid soils1 #cgf residual1 #ec ,limestones1 impure1 as soil-formers1 #dj1 #ec residual soils of1 how formed1 #dj soft1 or marls1 #dj slow disintegration of pure1 #fc ,limit of acid action on soils1 investigation of1 by ,loughridge1 #cdj ,limonite1 #dd ,loamy and sandy soils1 show little shrinkage1 #aag ,loose surface layer1 illustration of effect1 figure1 #beh1 #bfj prevention of evaporation by1 #beg ,loss of humus in summer mulch1 #acb ,louisiana1 vegetation and soil-characters1 #eab ,lowland tree-growth1 #ejf ,lysimeter1 #bbg ,m4 ,madagascar1 character and soils of1 #dje1 #djf climate and rocks of1 #djf methods used by ,mntz and ,rousseaux1 #djf potash and lime leached into valleys1 #djg red soils1 #djg1 #dji table of soil analyses1 #djh ,madras1 red soils of1 #dae ,magnesia1 effects of excess over lime1 #chb exceeds lime in tropical soils1 #dje high in arid soils1 #cha leached out next to lime1 #bd proper proportions to lime1 #chc ,magnesian limestones as soil-formers1 #db ,magnesian soils largely poor1 #cf ,magnetite1 #de ,maize and sorghums1 alkali-resistance1 #dga ,maize roots in humid and arid region1 #age1 #agf ,manganese1 more in humid than arid soils1 #chc stimulant effects on crops1 #chc ,marble and limestones1 formation of1 #ci ,marls1 gypseous and calcareous1 #dc ,marly substrata1 #ahf ,marine saline lands1 #ebg first crops for1 #ecc reclamation for culture1 #ecd ,matire noire2 active nitrification of1 #acb1 #cfj ,mechanical analysis of soils1 #hh ,melilots1 white and yellow1 alkali resistance1 #dgc ,mesas of arid region1 #ad ,mesopotamia1 rehabilitation of1 #dba ,metamorphic rocks1 #df ,methods of irrigation1 #bcf soil analysis1 #cbe ,mica as a soil ingredient1 #ce weathers slowly1 #ce mistaken for gold and silver1 #ce ,mica-schist soils1 #ea ,micro-organisms of soils1 #adb ,mineral fertilizers1 #fc ingredients of soils1 minor1 #fc ,minerals injurious to agriculture1 #gc major soil-forming1 and rock-forming1 list of1 #bi tints of1 #ah unessential or injurious to soils1 #ge ,mirabilite1 #gg ,mississippi1 changes in vegetation from east to west in northern1 #dij investigations in1 by writer1 #dhi northern1 vegetative belts in2 map1 #dij vegetative belts1 descriptions of1 #dij1 #dia1 #dib ,mississippi river1 sediment carried by1 #g ,mississippi1 southern1 central prairie1 long-leaf-pine belts1 #dic coast-belt2 pine meadows2 profile1 #die live-oak or shell hammocks1 #die ,mississippi valley1 climate of1 #bih ,mississippi water1 annual variations in1 #be generalized composition of1 #be ,modiola1 of ,chile1 #dfi ,moisture hygroscopic1 table1 #aif influence of temperature and air-saturation1 #aig method of determining1 #aig1 #aih ,mitscherlich's objections1 #aii utility to plant growth1 #aii available to growing plants1 #baa distribution in soil1 as affected by vegetation1 #bfd evaporated from forests1 #bfe ,eucalyptus1 #bfe in ,russian forests and steppes1 #bfe requirements of crops in the arid region1 #bab ,loughridge's tables of same1 #bad supplied by tap roots1 #bbi useful to crops retained by alkali lands1 #dcc wasted by weeds1 #bfd ,moraines1 in ,north ,central states1 #e ,mosses1 follow lichens in rock decomposition1 #bj ,moulds and fungi1 action of1 #abc ,mountain chains1 arid climate under lee of1 #bid effects of1 on rainfall1 #bic ,muddy waters1 #bea ,muir glacier1 analysis of mud1 #e ,mulches1 loss of humus1 #acb ,mulching with straw1 sand1 #bff ,mustard family1 sensitive to alkali1 #dgc ,myrobalan root1 use for grafting in alkali lands1 #dgi ,n4 ,native vegetation1 basis of land values for farmers1 #dhh causes governing its distribution not an unsolvable problem1 #dhi result of struggle for existence1 #dhg ,native grasses for alkali lands1 #dgj ,native growth1 cogency of conclusions based on1 #cad ,new ,mexico1 soils from2 analysis1 #cgh ,nile water1 ,letheby's analyses of1 #be ,nitrate deposits1 origin of1 #fg of soda1 #ff ,nitrates1 waste of1 by leaching1 #bd1 #fh ,nitrification1 active in matire noire1 #cfj ,nitrification and denitrification1 #ade in alkali lands1 #fh in soil of 8ten-acre tract401 #cei intensity in arid climates1 #fh list of substances favoring1 #adg of organic matter in soils1 experiments1 #ceh not active in unhumified matter1 #cei1 #cfj ,nitrifying ,bacteria1 #adf ,nitrobacterium2 conditions of activity1 #adf ,nitrogen-absorbing bacteria1 #aef ,nitrogen1 absorbed more abundantly than oxygen1 #bgh accumulation of1 in humus1 #abd adequacy in humus1 lowest limit of1 #cfc in soils1 #ceg availability of1 in soils2 ascertainable1 #cfc content of humus1 #ace deficiency1 pot test1 figure1 #cfb determination of1 in soils1 #ceg hungry soils2 table1 #cfa percentages in humus1 what are adequate1 #cfj supply of plants1 views on1 #aej ,nitrosomonas1 figure1 #bdf ,nodules of legumes1 #aea ,north ,central ,states1 herbaceous vegetation on calcareous soils1 #ead1 #eae lowland growth in uplands1 when1 #eae vegetation and soil-character1 #eac ,nutritive salts in alkali1 #dda ,o4 ,ocean currents1 ,gulf stream and ,japan stream1 #bie1 #bif ,olive1 resistance to alkali1 #dgh ,organic and organized constituents of soils1 #abj ,organisms influencing soil-conditions1 #adb ,oxalic acid1 secretion by lichens1 #ai ,oxidation1 expansion by1 #ah ,oxids constituting earth's crust2 table1 #ca ,oxygen1 action in weathering rocks1 #ah proportion of1 in earth's crust1 #cj ,p4 ,pamperos1 #i ,peat bogs1 #abb ,peaty soil1 shrinkage1 #aag ,percolation in natural soils3 diagram1 #bbc1 #bbe1 #bbf rate of1 as influenced by grain-sizes1 #bbd ,permanent value of land vs4 ,immediate productiveness1 #cdj ,physical and chemical causes of vegetative features1 #eje conditions of plant growth1 #cai ,physical analyses1 correlation with popular names1 #if results of1 #id table4 ,mississippi and ,california soils1 #ih analysis of soils1 #hh constituents of soils1 #aj ,physico-chemical investigation of soils1 #cac ,physiological soil analysis1 #ccc ,phosphate fertilizers1 importance of1 #fe ,phosphate fertilization1 in arid region1 #cic in ,california1 #cic ,phosphoric acid1 limits of adequacy in soils1 #cee minute amounts leached from soils1 #bd no constant difference between arid and humid soils1 #cic rendered inert by ferric hydrate1 #cee ,phosphorites1 low-grade1 of ,nevada1 ,russia1 #fc1 #fd ,plane tree1 oriental1 resistant to alkali1 #dhj ,plant-adaptation 8varying from province to province01 #ebc ,plant associations1 plant formations1 #cae ,plant distribution1 ,thurman's physical theory of1 #eai ,plant-development under different temperatures1 #cji ,plant-food1 accumulation in finest parts of soils1 #hg high percentages mean high land value1 #cdf ingredients1 condition of1 in soils1 #cai in virgin soils1 lowest limit of1 table1 #ceb limits of adequacy1 #cec minute amounts may produce large crops1 #daj percentages1 what are high1 #cdf percentages1 low1 #cdf water-soluble1 reserve1 unavailable1 #cbj ,plant-growth on arid subsoils1 #aff ,plants1 deep-rooting in arid region1 #agd indicating irreclaimable alkali lands1 #ece1 #ecf ,plant root action1 cannot be imitated in laboratory1 #cbd ,plasticity1 absence of1 in fine powders1 #fj of clay1 causes of1 #fj lost by burning1 #fj ,plot tests1 difficulties and uncertainties of1 #ccd plan of1 figure1 #cce ,plowsole1 how formed1 by shallow irrigation1 #ahf1 #bda ,poor chalk lands1 #ebe ,pore-space1 #ajh ,porosity of humus1 #abd ,port ,hudson bluff1 lignite in1 figure1 #abh recession of1 #aaf ,potash1 abundant in arid soils1 #cie and soda in arid and humid region1 #cid ,potashes1 production of detrimental to agriculture1 #fi ,potash feldspar1 supplies potash to soils1 #cb fertilization first in humid1 last in arid region1 #cif from sea water1 #fi limits of adequacy in soils1 #ced minerals1 orthoclase feldspar1 #fh preferential retention of1 in soils1 #bgb ,salts1 ,stassfurt1 #fi slightly leached out1 #bd sulfate1 high-grade1 #ga ,pot-culture tests1 #ccf ,powders1 absorption of various gases by1 table1 #bgg ,prairie soils1 black1 #ec ,preparation of soils for physical analysis1 #hi ,productive capacity and duration1 forecast of1 #cdf ,progress of humification and formation of coal1 table1 #abf1 #abg ,pulverulent soils of arid regions1 #hg ,purifying action of soils1 #bfi ,putrefactive processes1 relation to carbonic gas and anaerobic bacteria1 #bhb ,putty soils1 #ajc ,pyroxene1 augite1 #cc1 #cd ,q4 ,qualifications required for soil study1 #ebd ,quality of irrigation water1 #bdf ,quince1 resistance to alkali1 #dgi ,quartz and allied rocks1 #bi sand most prominent ingredient of soils1 #cj veins1 formation of1 #ca ,r4 ,rain belts1 temperate and tropical1 #bie ,rainfall1 amount of1 #bae distribution in ,california and ,montana1 #bij in the ,united ,states1 #bae most important1 #bij on the globe1 figure1 #bid influence on soil formation1 #bb insufficient1 forms alkali soils1 #bh leaves lime behind1 #bh natural disposition of1 #baf ,rains1 beating1 #bba cold and warm1 #cjb ,reclaimable and irreclaimable alkali lands1 #ecd ,red foothill soils of ,california1 #cd ,red or rust-colored soils1 #cd advantages of1 #bhd ,regur soils1 ,deccan1 ,india1 #dad formation of1 #dae 8guvarayi0 hardpan1 #dae present production1 #dad ,reh of ,india1 #ddj ,reserve plant-food in soils1 #cbj of zeolites1 carbonates1 phosphates1 #cba ,residual soils1 #aa1 #ac1 #bb ,rhizobia1 adaptation to symbiosis1 #aed inoculation of soils with1 #aed increase of crops by inoculation with1 #aee of legumes1 #aej mode of infection1 #aed varieties of forms1 #aed ,rhubarb1 sensitive to alkali1 #dge ,rhyolites1 soils from1 #ec ,river bars1 formation of1 #g ,rivers1 amount of dissolved matters carried by1 #bd flood-plains of1 #ac1 #ad sediment carried by1 #bd waters1 analyses of1 table1 discussion1 #bc1 #bd white and green1 #d ,rock crystal1 #bi ,rocks as soil-formers1 #dg chemical decomposition of1 #af cleavage of1 #c definition of1 xxiii disintegration of1 under extremes of temperature1 #b effects of heat and cold on1 #a erosion of by sand1 #aj forming minerals1 #bi fragments1 rounding of1 by flowing water1 #f ,rock powder1 #he ,rock-weathering in arid and humid climates1 #dg ,rohhumus1 #abb ,rolling of soils1 of influence of1 on heat1 #cje ,root action1 limitation of1 #cea ,root bacillus1 figure1 #adi1 #aej ,root crops1 effects of alkali upon1 #dgd ,root development in the arid and humid regions1 #afi to #agf ,rooting1 deep1 from proper irrigation1 #bdc1 #bde ,roots1 chemical action of1 #ba force exerted by1 #ai secrete carbonic acid1 #bj ,root system in the humid region2 figure1 #afh ,rotten ,limestone1 soils from1 analyses1 #ed ,runoff of rain water1 #baf ,russia1 black earth of2 roots and humus in1 #acj1 #cfc ,rye grass1 giant1 of ,northwest2 uses1 #dgj ,s4 ,saline and alkali lands1 vegetation of1 #ebg plants1 analyses of ashes of1 #ecj selective power of1 #eca ,saline and xerophile vegetation1 similarity of1 #ebh ,saline contents of waters1 variations of1 #bej solutions1 structural and functional differences caused by1 #ebh vegetation1 general character of1 #ebg ,saltbushes1 ,australian1 growth and use in ,california1 #dfi of ,great ,basin1 probable usefulness1 #dfh ,saltgrass2 range1 tolerance of alkali1 figure1 #edf1 #edg ,salton ,basin1 profile of salts in1 #dch ,salts1 absorption of1 by saline plants1 #ebi ,saltwort3 range1 tolerance of alkali1 figure1 #edj1 #edb ,samoa and ,kamerun soils1 analyses by ,wohltmann2 method1 #djb table of1 #djd ,samphire1 ,bushy and ,dwarf2 range1 alkali-tolerance1 figure1 #ech1 #eci1 #edj ,sand blasts1 effects on cobbles1 #aj coarse1 effect of1 on clays1 #aje erosion of rocks by2 figure1 #aj hammocks1 of ,gulf coast1 #ef ,sands of arid and humid regions1 differences in1 #hf1 #chf table of analyses1 #chg ,sand1 silt and dust1 #he ,sandstones1 #dh argillaceous1 #eg calcareous1 formation of1 #ef rich soils from1 #ef dolomitic1 often form poor soils1 #ef ferruginous1 poor soils from1 #ef siliceous1 poor soils from1 #ee varieties of1 #ee zeolitic1 soils from1 #eg ,sandstone soils1 lightness of1 #ee soils1 poor1 of humid region1 #ee ,sand storms1 #i ,sandy lands1 of arid regions1 highly productive1 #chf ,sandy soils1 #cj ,schne's elutriator1 figure1 #ij ,shrinkage1 extent of1 in drying soils2 figure1 #aac1 #aad ,schbler on calcareous soils1 #aae ,sea water1 average composition of1 table1 #bf chief ingredients useless to plants1 #bh minor constituents of1 #bg sources of salts in1 #bf ,sedentary soils1 #aa1 #ac1 #dj ,sedimentary rocks1 #dg1 #dh ,sediment deposited by ,mississippi in ,gulf1 #g ,sediments1 exhibition of1 from physical analysis1 #ie1 #if number of1 in physical analysis1 #ic table of diameters and hydraulic values1 #id ,seeds1 germination of1 #cji ,semi-humid and semi-arid region1 #cgg1 #cig ,serpentine1 #cf ,sieves1 use in physical analysis of soils1 #hh ,silica1 absorption and secretion by plants1 #ca and alumina1 soluble2 quantitative relations1 #che solubility in water1 #ca soluble1 retained in alkali soils1 #cia ,silicate minerals1 #ca ,silicates of soda and potash1 soluble1 #ca ,silicon1 abundance of1 in rocks1 xxxi ,silicophile plants1 a fiction1 #ebb ,sinkholes1 #dc ,soapstone1 #cf ,soda in arid and humid regions1 #cid ,soda1 nitrate of1 #ff ,sodium salts1 leached out by drains and rivers1 #bd ,soil analysis1 change of views regarding1 #cag discrepant methods used in1 #djb practical utility of1 #cah ,soil and subsoil1 causes and processes of differentiation1 #abj ill-defined1 #abj ,soil bacteria1 numbers of1 #ada ,soil character1 recognition from native vegetation1 #dhg1 #eaa ,soil-dilution experiments1 #cdg figures1 #cdh1 #cdi1 #cej table of1 #cej ,soil-examination1 short approximate methods for1 used at ,california station1 #efj summary directions for1 in field or farm1 #eef ,soil-formation influenced by rainfall1 #bb physical processes of1 #a ,soil-forming processes accelerated by high temperatures1 #cih ,soil-grains1 number of1 #ii surface of1 #ii determination by air-flow1 #ii by 8,benetzungswrme01 #ii investigation1 historical review of1 #cac moisture1 regulation and conservation of1 #bcd phosphates1 solubility in water2 ,schloesing fils1 #ccb probe1 mode of using1 #agg profiles in arid and humid region1 #afe ,soil1 samples1 directions for taking1 by ,calif4 ,station1 #eec sedentary or residual1 #aa1 #ac1 #dj study1 qualifications needed for1 #ebd surveys1 early1 of ,kentucky1 ,arkansas and ,mississippi1 #caf temperature1 annual range near surface in arctic and tropical regions1 #cjc change with depth2 table1 #cjc influence of evaporation on1 #cjg influence of soil material1 #cjf influence of surface conditions1 #cjc influence of vegetation and mulch1 #cje tests by crop analysis1 ,godlewski1 ,vanderyst1 #ccg1 #cch by extraction with organic acids2 ,dyer1 ,maxwell1 #cci water1 different conditions of1 #aie ,soils1 acid-soluble and water-soluble portions most important1 #cbd alluvial1 #ab1 #ac ancient1 in geological formations1 xxix calcareous1 definition of1 #cfg1 #dif1 #ebd classification of1 figure1 #aa colluvial1 #ab1 #bd definition of1 xxix derived from various rocks1 #di effects of crusting on1 #bba indefinite action of dilute acids on1 #cbf interpretation of analyses2 ,wohltmann1 #djc physico-chemical investigation of1 #cac 7see ,table of ,contents7 ,solar radiation1 influence of1 #cjb ,solubility1 continuous1 of soils in water1 #cbh ,king's table1 rich and poor soils1 #ccj ,schultze's table1 rich soil1 #cbh ,ulbricht's table1 poor soil1 #cbi ,solvent action of water upon soils1 #cbg power of water1 #ag ,solubility1 increased with nitrogen-content1 #ada ,sour grasses1 #abc humus1 antiseptic properties of1 #abb soils1 #abb ,souring of soils1 by cultivation1 #abc ,stable or farmyard manure1 #gb composition of1 table1 #gc green-manuring only substitute1 #gd method of using1 in humid region1 #gd physical effects of1 #gc use of1 in the arid region1 #gd ,stalactites and stalagmites1 #da ,stassfurt ,salts1 discovery of1 #fi importance to agriculture1 #gj origin of1 #gj ,stassfurt ,salts1 nature of1 #ga ,stonecrops1 succeed mosses1 #bj ,stone fruits1 resistance to alkali1 #dgh ,stratified rocks1 derived from crystalline1 #bi ,stunted growth1 caused by shallow or very heavy soils1 #ejd ,sturdy growth on calcareous lands1 #ejb1 #ejc ,subsidence method1 #hi ,subsoils1 arid region1 #afc and deep plowing1 #afd calcareous1 #afb rawness of1 in humid climates1 #afc ,substrata in arid region1 importance of1 #agc faulty1 with figures1 #agg to #ahj impervious1 injury from2 figure1 #aha leachy1 #ahb marly1 #ahf ,subterranean rivers1 #da ,sulfate of potash1 high-grade1 #ga of soda1 dust from1 #gg injuriousness to plants1 #gg occurrence in arid regions1 #gg ,sulfates1 reduction of1 #bcb ,sulfuric acid in arid and humid regions1 #cid ,summer mulch1 loss of humus in1 #acb ,sunflower family1 resistance to alkali1 #dgc ,sun's heat1 penetration into the soil1 #cjb ,surface crusts1 formation of1 #aaa1 #aag physical analyses of1 #aah ,surface1 hydrostatic and ground waters1 #bae ,surface waters1 chemical effects of percolation1 #afa physical effects of percolation1 #afa ,swamping of alkali lands1 consequences of1 #dea1 #dfc irrigated lands1 results of1 #bca ,symbiosis1 adaptation to1 of ,rhizobia1 #aed ,szek of ,hungarian plain1 #ddj ,t4 ,tabashir1 #ca ,talc and serpentine1 #cf ,tap-roots1 moisture supplied by1 #bbi ,tea1 failure on calcareous lands1 #dad ,temperature1 annual mean of1 #bhi conditions1 ascertainment and presentation of1 #bhh extremes1 on high mountains and plateaus1 #bhh of stellar space1 #bhh seasonal1 monthly and daily means1 #bhi1 #bia ,temporary vs4 permanent productive capacity of soils1 #cdj ,tennessee and ,kentucky1 vegetation and soil-character1 #eac ,terraces1 river and lake1 #ad ,testing penetration of irrigation water1 #bdb ,textile plants1 tolerance of alkali1 #dge ,thomas or basic slag1 #fd ,thurman's physical theory of plant distribution1 #eai ,tillage2 effects of2 figure1 #aji1 #aaj how maintained in nature1 #aaa ,titanium in soils1 xxxi ,time of acid-digestion1 different2 table1 #cdb ,tolerance of alkali by culture plants1 #dfc alkali plants2 table1 #edh1 #edi ,topography1 influence of1 on climate1 #bic ,trachytes1 #ec ,trona1 ,urao1 #gg ,tropical soils1 #cih are highly leached1 #djj often highly colored with iron1 #djj do not need early fertilization1 #cii humus in2 abundant1 but low in nitrogen1 #cii few determinations made1 #cii possible calculation of1 #cii investigations of1 #dja laterites1 not always rich in iron1 #djj mostly have low plant-food percentages1 #djj resemble the 8nimble penny01 #djj ,tubercles of legumes1 figures1 #aea1 #aed ,tufa1 calcareous1 #da ,tussock grass1 food value of1 #dgj range1 alkali-tolerance1 figure1 #ecf1 #ecg ,u4 ,ulmin substances1 #abb ,underdrainage1 advantages of1 #bce ,underdrains1 effects of1 #bcd ,unhumified organic matter does not nitrify1 #adh ,unhumified vegetable matter1 utility of1 #ace1 #cfj ,united ,states1 good field for comparative soil study1 #ebd ,upland and lowland growth in arid and humid regions1 #eae ,usar lands of ,india1 character of1 #ddj not all alkali lands1 #ddj ,v4 ,vegetative belts1 lime a governing factor of1 #dib ,virgin lands1 advantages of soil study in1 #cah ,virgin soils1 analysis by extraction with strong acids1 #cdj ,vivianite1 #fe ,volatile part of plants1 xxxii ,volcanic ash1 form soils rapidly2 soils from1 #bj1 #eb ,volcanic glass1 #ec ,volume of soils1 changes on wetting and drying1 #abb ,volume-weight of soils1 #ajg ,w4 ,walnut1 black1 a lime-loving tree1 #dij to #dig tolerant of white alkali1 #dgi ,washing-away and gullying of land1 #bag ,water1 capillary1 #bja ascent in soil columns1 figure1 #bjb1 #bje uniform sediments1 figure1 #bjd1 #bjg held at different heights in soil column1 table1 #bjh expansion and contraction in absorbing1 #bjh1 #bji maximum and minimum of water-holding power1 termination of2 figure1 #bjb1 #bjg movements in moist soils1 #baj carbonated1 solvent power1 #ag carrying power1 #ad controlling factor of soil temperature1 #cja density of1 #aij effects of flowing1 #e ,water extraction of soils1 practical conclusions from1 #ccb ,water1 hard1 #da hygroscopic1 #aif of lan-locked lakes1 #bg loss of1 by irrigation in shallow furrows1 #bdj physical factors of1 #ahh regulation of temperature by1 #aia relations to heat1 #ahi requirements of growing plants1 #aib plants in arid regions1 #aie sidewise penetration of1 in soils1 #bda of soils1 chapters on1 #ahh1 #bae1 #bcd solvent action upon soils1 #cbg solvent power1 #ag1 #aia ,water-soluble plant-food1 #cba specific heat of1 #aij1 #aia table1 #bbg vaporization of1 #aia ,watery soil extracts1 from ,european soils2 tables1 #cbg1 #cbi ,american soils1 ,king1 #cbi1 #ccj ,wave action on shores1 figure1 #g ,weathering1 by oxygen1 carbonic acid1 water1 #af1 #ag 8 in humid and arid regions1 #b1 #hf ,weight of soils1 per acre-foot1 #ajg ,white soils1 nature of1 in humid regions1 #bhe in arid regions1 #bhf ,wind deposits1 #aje ,winds1 action of1 in forming soils1 #h cyclones1 and anti-cyclones1 #bic effects of1 in deserts1 #h heat the cause of1 #bia land and sea breeze1 #bia trade1 and monsoons1 #bia1 #bib ,winter irrigation1 #bcf ,wire-basket tests1 of ,bureau of ,soils1 #ccg ,x4 ,xerophile vegetation1 similarity to saline1 #ebi ,y4 ,yazoo bottom1 soils of1 #aaf ,yazoo 8buckshot0 and ,arroyo ,grande soils1 #cde ,z4 ,zeolites1 decomposition by acids1 #cf1 #ch1 #ci exchange of bases in analcite and leucite1 #cg formation of1 #cg importance in soils1 #ch rocks cemented by1 #ch ,zeolitic sandstones1 #eg ,,authors ,,referred ,,to4 ,,note4--,in cases where no special credit is given in this volume for investigations made or data given from the ,southwestern ,states and the ,pacific ,coast1 these should be understood as work done1 mostly under the writers direction1 or by himself and assistants1 in connections with the geological surveys of ,mississippi and ,louisiana1 as well as the ,tenth ,census of the ,united ,states1 by ,drs4 ,eugene ,a4 ,smith and ,r4 ,h4 ,loughridge2 the chemical work for the ,pacific ,northwest1 under the auspices of the ,northern ,transcontinental ,survey1 by ,m4 ,e4 ,jaffa and ,geo4 ,e4 ,colby2 that in ,california1 at the ,experiment ,station1 by the latter two1 ,dr4 ,r4 ,h4 ,loughridge1 and temporary assistants4 ,it would be impossible to segregate1 without excessive prolixity1 the credit to be assigned to each of these participants4 ,a4 ,adametz1 ,l41 #adb1 #bha4 ,agassiz1 ,l41 #d4 ,aso1 ,k41 #chc4 ,b4 ,bamber1 --1 #dja1 #daj1 #dad4 ,batholomew1 ,j4 ,g4 #bid4 ,beyerinck1 ,m4 ,w41 #aea1 #aef4 ,blumtritt1 ,e41 #bgf4 ,bonnier1 ,g41 #eba4 ,bttcher1 ,o41 #cic4 ,boussingault1 ,j4 ,b41 #aea1 #bgf1 #cac4 ,brick1 --1 #ebh4 ,brock1 see ,morck1 ,d4 ,burri1 ,r41 #adh4 ,butler1 ,o41 #aea4 ,c4 ,cameron1 ,f4 ,k41 #chj1 #dff1 #ecb1 #ecc4 ,clarke1 ,f4 ,w41 ,,xxiv1 #bc4 ,colby1 ,g4 ,e41 note above4 ,colmore1 ,c4 ,a41 #ddh4 ,contejean1 ,ch41 #eba1 #ebc1 #eca4 ,coville1 ,f4 ,v41 #ecf4 ,crochetelle1 ,j41 #adf1 #adg4 ,d4 ,darton1 ,n4 ,h41 #aj4 ,darwin1 ,ch41 #aeh4 ,davy1 ,j4 ,b41 #ece4 ,deherain1 ,p4 ,p41 #adf1 #adg4 ,detmer1 ,w41 #abg4 ,djemil1 --1 #aei4 ,duclaux1 ,p4 ,e41 #add4 ,duggar1 ,j4 ,f41 #aee4 ,dumont1 ,j41 #adf1 #adg4 ,dyer1 ,b41 #cci1 #ceg4 ,e4 ,ebermayer1 ,e41 #bgi1 #cje4 ,eckart1 ,c4 ,f41 #bab4 ,eichorn1 --1 #cbg4 ,ermann1 ,g4 ,a41 #cjc4 ,f4 ,fawcett1 ,w41 #cee4 ,fischer1 ,hugo1 #aef4 ,fliche1 ,p41 #ebj1 #eba4 ,forbes1 ,r4 ,h41 #bai4 ,fortier1 ,s41 #aid1 #bed4 ,fraenkel1 ,l41 #adb4 ,frank1 ,a41 #aea4 ,fuelles1 ,p41 #bha4 ,furry1 ,f4 ,e41 #gc4 ,furuta1 ,t41 #chc4 ,g4 ,geikie1 ,j41 #ad4 ,gerlach1 --1 #aef4 ,gilbert1 ,g4 ,k41 #b4 ,gilbert1 ,j4 ,h41 #aea1 #aib4 ,godlewski1 ,e41 #ccg1 #cic ,goss1 ,a41 #cgf1 #ecj4 ,grandeau1 ,l41 #acb1 #acc1 #aci1 #ceg1 #ebj1 #eba4 ,h4 ,haberlandt1 ,f41 #caj4 ,hall1 ,a4 ,d41 #baj1 #bbg4 ,hare1 ,r4 ,f41 #cgh4 ,harper1 ,r4 ,m41 #did4 ,hartwell1 ,b4 ,l41 #abc4 ,headden1 ,h4 ,p41 #ah4 ,hedin1 ,sven1 #i4 ,hellriegel1 ,f41 #acj1 #aea1 #aib4 ,henrici1 #bjj4 ,hillman1 ,f4 ,h41 #ecf4 ,hiltner1 ,l41 #aed4 ,hoffmann1 ,r41 #ebh4 ,hohl1 ,j41 #adc4 ,hunt1 ,t4 ,s41 #bc4 ,j4 ,jaffa1 ,m4 ,e41 #ace1 #cha1 #dej1 #ecj4 ,johnson1 ,s4 ,w41 #fj1 #chj4 ,k4 ,katayama1 ,t41 #chc4 ,kearney1 ,t4 ,h41 #ecb4 ,kedzie1 ,r4 ,c41 #cdc1 #cge4 ,kellner1 ,o41 #cic4 ,king1 ,f4 ,h41 #ii1 #ajh1 #aji1 #afh1 #aib1 #aic1 #baj1 #baa1 #bab1 #bbd1 #bbh1 #bcf1 #cje1 #cbe1 #cbh1 #ccb4 ,kinsley1 ,j4 ,s41 #adc4 ,knop1 ,w41 #aig4 ,koch1 ,r41 #aef1 #bha4 ,kossovitch1 ,p41 #cfc4 ,kosticheff1 ,p41 #acj1 #aeg4 ,krber1 #aef4 ,krocker1 ,f41 #bb4 ,kuntze1 ,o41 #fg1 #fh4 ,l4 ,ladd1 ,e4 ,f41 #aca1 #acc1 #acd1 #ada4 ,langley1 ,s4 ,p41 #bhh4 ,lawes1 ,j41 #aea1 #aib4 ,lea1 ,e4 ,c41 #chg4 ,leather1 ,j4 ,w41 #dja1 #daj1 #daa1 #dab1 #dad to #dag1 #ddj4 ,lemberg1 ,j41 #bgb ,lesage1 ,m41 #ebh4 ,letheby1 ,h41 #bc4 ,liebig1 ,j4 von1 #aej1 #cac4 ,liebscher1 ,g41 #ced4 ,lipman1 ,j4 ,g41 #aef4 ,loeb1 ,j41 #chj4 ,loew1 ,o41 #bc1 #db1 #chb1 #chc4 ,loughridge1 ,r4 ,h41 #hg1 #bjg1 #bac1 #bad1 #bdj1 #bei1 #cdj to #cdb1 #che1 #dcj1 #dfb1 #dff1 #eac1 #ece1 #efj4 ,m4 ,maercker1 ,m41 #fe1 #cfi4 ,mann1 ,h4 ,h41 #dja1 #daj1 #dac4 ,manson1 ,m41 #bid4 ,maxwell1 ,w41 #cci4 ,may1 ,d4 ,w41 #db1 #chj4 ,mayer1 ,a41 #aii1 #bjg1 #bji4 ,mayo1 ,n4 ,s41 #adc4 ,mazurenko1 ,d4 ,p41 #hg4 ,means1 ,t4 ,h41 #bdh1 #dgh4 ,merrill1 ,g4 ,p41 #b1 #ac1 #afg4 ,middendorff1 ,v41 #dda4 ,mitscherlich1 ,e4 ,a41 #ii1 #aii4 ,miquel1 ,p41 #adb1 #bha1 #cei4 ,mohr1 ,chas41 #dhi1 #eaa4 ,moore1 ,g4 ,t41 #aed4 ,morck1 ,d41 #aed4 ,mller1 ,a41 #ddi4 ,mller1 ,p4 ,e41 #abb1 #ahd4 ,mntz1 ,a41 #adb1 #cee1 #cgj1 #dja1 #djb1 #djf to #daj4 ,murray1 ,john1 #bc1 #bd4 ,myers1 ,h4 ,c41 #f1 #add4 ,n4 ,naegeli1 ,c4 v41 #abi4 ,nagaoka1 ,m41 #fe1 #cic4 ,nobbe1 ,f41 #aed4 ,o4 ,osterhout1 ,w4 ,j4 ,v41 #ecc4 ,ototzky1 ,l41 #bfe4 ,owen1 ,d4 ,d41 #caf1 #cag1 #cdc1 #eac4 ,p4 ,peter1 ,a4 ,m41 #age4 ,peter1 ,r41 #caf1cag1 #cdc4 ,pichard1 ,p41 #adg4 ,porter1 ,j4 ,l41 #bc1 #bd4 ,pumpelly1 ,r41 #aaj4 ,r4 ,rafter1 ,g4 ,w41 #bag4 #bjd,ramann1 ,e4 ,reade1 ,t4 ,m41 #da4 ,regnault1 ,v41 #bf4 ,reichert1 ,e41 #bgf4 ,richthofen1 ,f4 von1 #aaj4 ,risler1 ,e41 #ced4 ,rosenberg1 ,s41 #ebh4 ,rousseaux1 ,e41 #cee1 #cgj1 #dja1 #djb1 #djf to #daj4 ,rudzinski1 ,d41 #hg4 ,russell1 ,i4 ,c41 #bd4 ,s4 ,saussure1 ,h4 ,e4 de1 #aej4 ,schimper1 ,a4 ,f4 ,w41 #ebc1 #ebh4 ,schloesing1 ,th41 #ei1 #aaa1 #ced4 ,schloesing1 ,th41 fils1 #ccb1 #cic4 ,schmidt1 ,c41 #bc4 ,schne1 ,h4 ,e41 #ij4 ,schbler1 ,j4 ,j41 #aaf1 #aig1 #cac4 ,schultze1 ,h41 #cbh1 #cbi4 ,seton1 ,e4 ,t41 #aei1 #afj4 ,shaler1 ,n4 ,s41 #ab4 ,shaw1 ,g4 ,w41 #dfe4 ,smith1 ,e4 ,a41 #eaa4 ,snyder1 ,h41 #aca1 #acc1 #acd1 #aci4 ,stenhouse1 --1 #bgf4 ,stockbridge1 ,h4 ,e41 #cjg1 #cjh4 ,stone1 ,c4 ,h4 ,h41 #be4 ,stubenrauch1 ,a4 ,v41 #bbb4 ,stutzer1 ,a41 #adi4 ,t4 ,thurmann1 ,j41 #eai1 #ebj4 ,tolman1 ,l4 ,m41 #chg4 ,tourney1 ,j4 ,w41 #baf4 ,traphagen1 ,f4 ,w41 #bc4 ,tuxen1 ,c4 ,f4 ,a41 #ahd4 ,u4 ,udden1 ,j4 ,a41 #ajf4 ,ulbricht1 ,r41 #cbh4 ,v4 ,vanderyst1 ,h41 #cch4 ,ville1 ,g41 #aea4 ,voelcker1 ,j4 ,a41 #bb1 #daj4 ,vogel1 ,j4 ,h41 #aef4 ,w4 ,wagner1 ,p41 #fe4 ,ward1 ,m41 #add4 ,warington1 ,r41 #ajh1 #adf4 ,washington1 ,h4 ,s41 xxiv4 ,way1 ,j4 ,t41 #bb1 #gc4 ,weber1 ,a4 ,h41 #dej4 ,wheeler1 ,h4 ,j41 #abc4 ,whitney1 ,m41 #id1 #aie1 #bjg1 #caf1 #cba1 #ccj1 #ccb1 #ccg4 ,wilfarth1 ,h41 #aea4 ,williams1 ,w4 ,e41 #fj1 #ajj4 ,winogradsky1 ,s41 #adf1 #aef4 ,wohltmann1 ,f41 #cee1 #cgj1 #dja1 #djb to #dje1 #djf1 #daf4 ,wolff1 ,e41 #bb1 #gc4 ,wollny1 ,e41 #aaj1 #aac1 #abe1 #adg1 #aei1 #aie1 #bfd1 #bgi1 #bha1 #bhd1 #cje1 #cjf4 ,wllner1 --1 #aih4 ,wunder1 ,g41 #cbg4 ,y4 ,yoder1 ,p4 ,a41 #ib4 ,z4 ,zller1 ,p4 ,h41 #bb4 #bjd ,this writer's valuable 8,boden ,runde0 7#aije7 unfortunately came to hand too late to be considered in this volume4 ,printed in the ,united ,states of ,america4