,historical ,literature in ,agriculture 7,,chla71 ,cornell ,university7 ,,principles ,,of ,,manuring ,,manures ,,and ,,the ,,principles ,,of ,,manuring ,,by ,c4 ,m4 ,,aikman1 ,m4,a41 ,d4,sc41 ,f4,r4,s4,e41 ,f4,i4,c4 ,,formerly ,,professor ,,of ,,chemistry1 ,,glasgow ,,veterinary ,,college1 ,,and ,,examiner ,,in ,,chemistry1 ,,glasgow ,,university2 ,,author ,,of ',,farmyard ,,manure1' ,,etc4 ,,third ,,impression ,,william ,,blackwood ,,and ,,sons ,,edinburgh ,,and ,,london ,,mcmx ,d4 ,,van ,,nostrand ,,company ,,new ,,york ,all ,rights reserved ,,to ,,sir ,,john ,,bennet ,,lawes1 ,,bart41 ,d4,c4,l41 ,,ll4,d41 ,f4,r4,s41 ,,of ,,rothamsted1 ,,and ,,sir ,j4 ,,henry ,,gilbert1 ,m4,a41 ,,ll4,d41 ,f4,r4,s41 ,,formerly ,,sibthorpian ,,professor ,,of ,,rural ,,economy1 ,,university ,,of ,,oxford1 ,,whose ,,famous ,,investigations ,,during ,,the ,,last ,,fifty ,,years ,,have ,,so ,,largely ,,contributed ,,to ,,build ,,up ,,the ,,science ,,of ,,manuring1 ,,this ,,work1 ,,embodying ,,many ,,of ,,the ,,rothamsted ,,results1 ,,is ,,dedicated4 ,,preface4 ,when the present work was first undertaken there were but few works in ,english dealing with its subject-matter1 and hardly any which dealt with the question of ,manuring at any length4 ,during the last few years1 however1 owing to the greatly increased interest taken in agricultural education1 the demand for agricultural scientific literature has called into existence quite a number of new works4 ,despite this fact1 the author ventures to believe that the gap which the present treatise was originally designed to fill is still unfilled4 ,of the importance of the subject all interested in agriculture are well aware4 ,it is no exaggeration to say that the introduction of the practice of artificial manuring has revolutionised modern husbandry4 ,indeed1 without the aid of artificial manures1 arable farming1 as at present carried out1 would be impossible4 ,fifty years ago the practice may be said to have been unknown2 yet so widespread has it now become1 that at the present time the capital invested in the manure trade in this country alone amounts to millions sterling4 ,it need scarcely be pointed out1 therefore1 that a practice in which such vast monetary interests are involved is worthy of the most careful consideration by all students of agricultural science1 as well as1 it may be added1 by political economists4 ,the aim of the present work is to supply in a concise and popular form the chief results of recent agricultural research on the question of soil fertility1 and the nature and action of various manures4 ,it makes no pretence to be an exhaustive treatise on the subject1 and only contains those facts which seem to the author to have an important bearing on agricultural practice4 ,in the treatment of its subject it may be said to stand midway between ,professor ,storer's recently published elaborate and excellent treatise on ',agriculture in some of its ,relations to ,chemistry'--a work which is to be warmly recommended to all students of agricultural science1 and to which the author would take this opportunity of acknowledging his indebtedness--and ,dr ,j4 ,m4 ,h4 ,munro's admirable little work on ',soils and ,manures4' ,in order to render the work as intelligible to the ordinary agricultural reader as possible1 all tabular matter and matter of a more or less technical nature have been relegated to the ,appendices attached to each chapter4 ,the author's somewhat wide experience as a ,university ,extension ,lecturer1 and as a ,lecturer in connection with ,county ,council schemes of agricultural education1 during the last few years1 induces him to believe that the work may be of especial value to those engaged in teaching agricultural science4 ,he has to express the deep obligation he is under1 in common with all writers on ,agricultural ,chemistry1 to the classic researches of ,sir ,john ,bennet ,lawes1 ,bart41 and ,sir ,j4 ,henry ,gilbert1 now in progress for more than fifty years at ,sir ,john ,lawes' ,experiment ,station at ,rothamsted4 ,his debt of gratitude to these distinguished investigators has been still further increased by their kindness in permitting him to dedicate the work to them1 and for having been good enough to read portions of the work in proof4 ,in addition to the free use which has been made throughout the book of the results of these experiments1 the last chapter contains1 in a tabular form1 a short epitome of some of the more important ,rothamsted researches on the action of different manures4 ,to the numerous ,german and ,french works on the subject1 more especially to ,professor ,heiden's encyclopaedic ',lehrbuch der ,duengerlehre' and the various writings of ,dr ,emil von ,wolff1 the author is further much indebted4 ,among ,english works he would especially mention the assistance he has derived from the writings of ,mr ,r4 ,warington1 ,f4,r4,s41 ,professor ,s4 ,w4 ,johnson1 ,professor ,armsby1 the late ,dr ,augustus ,voelcker1 and others4 ,he would also tender his acknowledgments to the new edition of ,stephens' ',book of the ,farm1' and he has to thank its editor1 his friend ,mr ,james ,macdonald1 ,secretary to the ,highland and ,agricultural ,society of ,scotland1 for having read parts of his proof-sheets4 ,it is also his pleasing duty to thank his friends ,dr ,bernard ,dyer1 ,hon ,secretary of the ,society of ,public ,analysts1 ,dr ,a4 ,p4 ,aitken1 ,chemist to the ,highland and ,agricultural ,society of ,scotland2 ,professor ,douglas ,gilchrist of ,bangor2 ,mr ,f4 ,j4 ,cooke1 late of ,flitcham2 ,mr ,hermann ,voss of ,london2 and ,professor ,wright of ,glasgow1 for having assisted him in the revision of proof-sheets4 ,,analytical ,,laboratory1 #abh ,,wellington ,,street1 ,,glasgow1 ,january #ahid4 ,,contents4 ,,part ,i4--,,historical ,,introduction4 ,,page ,beginning of agricultural chemistry #d ,early theories regarding plant-growth #d ,van ,helmont #d ,digby #f ,duhamel and ,stephen ,hales #h ,jethro ,tull #i ,charles ,bonnet's discovery of source of plants' carbon #aa ,researches of ,priestley1 ,ingenhousz1 ,senebier1 on assimilation of carbon #aa-ab ,publication of first ,english treatise by ,earl ,dundonald #ac ,publication of ,theodore de ,saussure1 ',chemical ,researches on ,vegetation1' #ahjd #ad ,theories on source of plant-nitrogen #ae ,early experiments on this subject #af ,sir ,humphry ,davy's lectures 7#ahjb-ahab7 #ag ,state of agricultural chemistry in #ahab #ag ,beginning of ,boussingault's researches 7#ahcd7 #ba ,publication of ,liebig's first report to the ,british ,association #bd ,refutation of humus theory #bf ,liebig's mineral theory #bf ,liebig's theory of source of plants' nitrogen #bg ,publication of ,liebig's second report to ,british ,association #cj ,liebig's services to agricultural chemistry #ca ,development of agricultural research in ,germany #cb ,the ,rothamsted ,experiment ,station #cc ,sir ,j4 ,b4 ,lawes and ,sir ,j4 ,h4 ,gilbert1 the nature and value of their experiments #cc ,review of the present state of our knowledge of plant-growth #cf ,proximate composition of the plant #cf ,fixation of carbon by plants #cg ,action of light on plant-growth1 ,dr ,siemens' experiments #ch ,source of oxygen and hydrogen in the plant #ci-dj ,source of nitrogen in the plant #dj ,relation of the free nitrogen to leguminous plants #db-dd ,relation of nitrogen in organic forms1 as ammonia salts1 and nitrates to the plant #df-ej ,nitrification and its conditions #ea ,ash constituents of the plant #ec ,methods of research for ascertaining essentialness of ash constituents of plants #ec 7a7 ,artificial soils1 7b7 water-culture #ec-ee ,method in which plants absorb their food-constituents #ee ,endosmosis #ee ,retention by soils of plant-food #eg ,causes of retention by soils of plant-food #ei ,manuring #fj ,field and pot experimentation #fj ,,part ,,ii4--,,principles ,,of ,,manuring4 ,,chapter ,i4--,,fertility ,,of ,,the ,,soil4 ,what constitutes fertility in a soil #fe ,i4 ,physical properties of a soil #ff ,kinds of soils #fg ,absorptive power for water of soils #fg ,absorptive power for water of sand1 clay1 and humus #fh ,fineness of particles of a soil #fi ,limit of fineness of soil-particles #fi ,importance of retentive power #gj ,power of plants for absorbing water from a soil experiments by ,sachs #gc ,how to increase absorptive power of soils #gd ,amount of water in a soil most favourable for plant growth #ge ,hygroscopic power of soils #ge ,capacity of soils for absorbing and retaining heat #gf ,explanation of dew #gg ,heat of soils #gh ,heat in rotting farmyard manure #gh ,causes of heat of fermentation #gi ,influence of colour on heat-retaining power #hj ,power of soils for absorbing gases #ha ,gases found in soils #ha ,variation in gas-absorbing power of soils #hb ,absorption of nitrogen by soils #hb ,requirements of plant-roots in a soil #hc ,influence of tillage on number of plants in a certain area #hf ,comparison of ,english and ,american farming #hf ,,ii4 ,chemical composition of a soil #hg ,fertilising ingredients of a soil #hg ,importance of nitrogen1 phosphoric acid1 and potash in a soil #hh ,chemical condition of fertilising ingredients in soils #hi ,amount of soluble fertilising ingredients in soils #ij ,value of chemical analysis of soils #ij ,,iii4 ,biological properties of a soil #ib ,bacteria of the soil #ib ,recapitulation of ,chapter ,i #if ,,appendix ,,to ,,chapter ,i4 ,,note ,i4 ,table of absorptive power of soil substances by ,schuebler #ih ,,ii4 ,table of rate of evaporation of water in different soils by ,schuebler #ii ,,iii4 ,table of hygroscopic power of soils dried at #bab deg4 ,f4 7,davy7 #ii ,,iv4 ,gases present in soil #ajj ,v4 ,amount of plant-food in soils #ajj ,,vi4 ,chemical composition of the soil #aja ,,vii4 ,forms in which plant-foods are present in the soil #ajg ,,chapter ,,ii4--,,functions ,,performed ,,by ,,manures4 ,etymological meaning of word manure #aji ,definition of manures #aaj ,different classes of manures #aaa ,action of different classes of manures #aac ,,chapter ,,iii4--,,position ,,of ,,nitrogen ,,in ,,agriculture4 ,the ,rothamsted experiments and the nitrogen question #aae ,different forms in which nitrogen exists in nature #aaf ,relation of free nitrogen to the plant #aag ,combined nitrogen in the air #aah ,amount of combined nitrogen falling in the rain #aai ,nitrogen in the soil #abj ,nitrogen in the subsoil #aba ,nitrogen of surface-soil #aba ,amount of nitrogen in the soil #abc ,soils richest in nitrogen #abc ,nature of the nitrogen in the soil #abd ,organic nitrogen in the soil #abe ,differences of surface and subsoil nitrogen #abf ,nitrogen as ammonia in soils #abg ,amount of ammonia in soils #abg ,nitrogen present as nitrates in the soil #abh ,position of nitric nitrogen in soil #abh ,amount of nitrates in the soil #abi ,amount of nitrates in fallow soils #abi ,amount of nitrates in cropped soils #acj ,amount of nitrates in manured wheat-soils #aca ,the sources of soil-nitrogen #aca ,accumulation of soil-nitrogen under natural conditions #acc ,accumulation of nitrogen in pastures #acd ,gain of nitrogen with leguminous crops #ace ,the fixation of free nitrogen #acf ,influence of manures in increasing soil-nitrogen #acf ,sources of loss of nitrogen #acg ,loss of nitrates by drainage #acg ,prevention of loss of nitrogen by permanent pasture and catch-cropping #ach ,other conditions diminishing loss of nitrates #aci ,amount of loss of nitrogen by drainage #adj ,loss of nitrogen in form of free nitrogen #ada ,total amount of loss of nitrogen #adb ,loss of nitrogen by retrogression #adb ,artificial sources of loss of nitrogen #add ,amount of nitrogen removed in crops #add ,losses of nitrogen incurred on the farm #adf ,loss in treatment of farmyard manure #adf ,nitrogen removed in milk #adg ,economics of the nitrogen question #adg ,loss of nitrogen-compounds in the arts #adh ,loss due to use of gunpowder #adh ,loss due to sewage disposal #adi ,our artificial nitrogen supply #aej ,nitrate of soda and sulphate of ammonia #aej ,peruvian guano #aea ,bones #aea ,other nitrogenous manures #aeb ,oil-seeds and oilcakes #aec ,other imported sources of nitrogen #aec ,conclusion #aec ,,appendix ,,to ,,chapter ,,iii4 ,,note ,i4 ,determination of the quantity of nitrogen supplied by rain1 as ammonia and nitric acid1 to an acre of land during one year #aee ,,ii4 ,nitrogen in soils at various depths #aef ,,iii4 ,nitrogen as nitrates in cropped soils receiving no nitrogenous manures1 in lb4 per acre 7,rothamsted soils7 #aeg ,,iv4 ,nitrogen as nitrates in ,rothamsted soils #aeg ,v4 ,examples of increase of nitrogen in ,rothamsted soils laid down in pasture #aeh ,,vi4 ,loss by drainage of nitrates #aeh ,,vii4 ,examples of decrease of nitrogen in ,rothamsted soils #aei ,,viii4 ,amount of drainage and nitrogen as nitrates in drainage-water from unmanured bare soil1 #bj and #fj inches deep #afj ,,chapter ,,iv4--,,nitrification4 ,process of nitrification #afa ,occurrence of nitrates in the soil #afb ,nitre soils of ,india #afb ,saltpetre plantations #afc ,cause of nitrification #afe ,ferments effecting nitrification #afg ,appearance of nitrous organisms #afh ,nitric organism #afi ,difficulty in isolating them #afi ,nitrifying organisms do not require organic matter #afi ,conditions favourable for nitrification-- ,presence of food-constituents #agj ,presence of a salifiable base #aga ,only takes place in slightly alkaline solutions #agb ,action of gypsum on nitrification #agc ,presence of oxygen #agc ,temperature #age ,presence of a sufficient quantity of moisture #agf ,absence of strong sunlight #agf ,nitrifying organisms destroyed by poisons #agf ,denitrification #agg ,denitrification also effected by bacteria #agh ,conditions favourable for denitrification #agh ,takes place in water-logged soils #agi ,distribution of the nitrifying organisms in the soil #agi ,depth down at which they occur #ahj ,action of plant-roots in promoting nitrification #aha ,nature of substances capable of nitrification #aha ,rate at which nitrification takes place #ahc ,nitrification takes place chiefly during summer #ahc ,process goes on most quickly in fallow fields #ahd ,laboratory experiments on rate of nitrification #ahe ,certain portions of soil-nitrogen more easily nitrifiable than the rest #ahg ,rate of nitrification deduced from field experiments #ahg ,quantity of nitrates formed in the soils of fallow fields #ahh ,position of nitrates depends on season #ahh ,nitrates in drainage-waters #ahh ,amount produced at different times of year #ahi ,nitrification of manures #aij ,ammonia salts most easily nitrifiable #aia ,sulphate of ammonia the most easily nitrifiable manure #aia ,rate of nitrification of other manures #aib ,soils best suited for nitrification #aib ,absence of nitrification in forest-soils #aic ,important bearing of nitrification on agricultural practice #aic ,desirable to have soil covered with vegetation #aid ,permanent pasture most economical condition of soil #aid ,nitrification and rotation of crops #aie ,,appendix ,,to ,,chapter ,,iv4 ,,note ,i4 ,old theories of nitrification #aif ,,ii4 ,nitrification takes place in solutions devoid of organic matter #aif ,,iii4 ,oxidising power of micro-organisms in soils #aig ,,iv4 ,effect of urine on nitrification in soils #aig ,v4 ,solution used by ,professor ,frankland in cultivating nitrificative micro-organisms #aih ,,vi4 ,experiments by ,boussingault on rate of nitrification #aih ,,vii4 ,nitrogen as nitrates in ,rothamsted soils after bare fallow in lb4 per acre #aih ,,chapter ,v4--,,position ,,of ,,phosphoric ,,acid ,,in ,,agriculture4 ,occurrence of phosphoric acid in nature #aii ,mineral sources of phosphoric acid #bjj ,apatite and phosphorite #bjj ,coprolites #bja ,occurrence of phosphoric acid in guanos #bjb ,universal occurrence in common rocks #bjb ,occurrence in the soil #bjc ,condition in which phosphoric acid occurs in the soil #bjc ,occurrence in plants #bjd ,occurrence in animals #bje ,sources of loss of phosphoric acid in agriculture #bje ,loss of phosphoric acid by drainage #bjf ,artificial sources of loss of phosphoric acid #bjf ,amount of phosphoric acid removed in milk #bjg ,loss of phosphoric acid in treatment of farmyard manure #bjh ,loss of phosphoric acid in sewage #bjh ,sources of artificial gain of phosphoric acid #bjh ,,appendix ,,to ,,chapter ,v4 ,,note ,i4 ,composition of apatite 7,voelcker7 #baj ,,ii4 ,percentage of phosphoric acid in the commoner rocks #baa ,,chapter ,,vi4--,,position ,,of ,,potash ,,in ,,agriculture4 ,potash of less importance than phosphoric acid #bab ,occurrence of potash #bac ,felspar and other potash minerals #bac ,stassfurt salts #bad ,occurrence of saltpetre #bae ,occurrence of potash in the soil #bae ,potash chiefly in insoluble condition in soils #baf ,percentage of potash in plants and plant-ash #baf ,occurrence of potash in animal tissue #bag ,sources of loss of potash #bag ,amount of potash removed in crops #bah ,amount of potash removed in milk #bah ,potash manures #bah ,,appendix ,,to ,,chapter ,,vi4 ,,note ,i4 ,amount of potash in different minerals #bbj ,,ii4 ,quantity of potash obtained from #ajjj lb4 of different kinds of vegetation in the manufacture of potashes #bbj ,,part ,,iii4--,,manures4 ,,chapter ,,vii4--,,farmyard ,,manure4 ,variation in its composition #bbc ,made up of three classes of constituents #bbd ,solid excreta-- ,its nature #bbd ,difference in composition of the solid excreta of the different farm animals #bbd ,causes of this difference #bbe ,percentage of manurial ingredients in solid excreta of different animals #bbf ,urine-- ,its nature #bbh ,variation in its composition #bbi ,causes of this variation #bbi ,manurial value of the urine of the different farm animals #bcj ,percentage of the organic matter1 nitrogen1 and mineral substances in the food1 voided in the solid excreta and urine #bcb ,comparison of manurial value of total excrements of the different farm animals #bcd ,nature of changes undergone by food in process of digestion #bce ,litter-- ,its uses #bcf ,straw as litter1 and its qualifications #bcg ,composition of different kinds of straw #bch ,loam as litter #bci ,peat as litter #bdj ,comparison of properties of peat-moss and straw #bda ,the bracken-fern as litter #bda ,dried leaves as litter #bdb ,manures produced by the different animals-- ,horse-manure-- ,amount produced #bdc ,its nature and composition #bdc ,amount of straw used for litter #bdd ,sources of loss on keeping #bde ,how to prevent loss #bde ,use of fixers1 and the nature of their action #bde ,cow-manure-- ,amount produced #bdh ,its nature and composition #bdh ,amount of straw used as litter #bdh ,sources of loss on keeping #bdi ,advantages of short dung #bdi ,pig-manure-- ,amount produced #bej ,its nature and composition #bej ,amount of straw used as litter #bea ,sheep-manure-- ,amount produced #bea ,nature and composition #bea ,amount of straw used as litter #beb ,methods of calculating amount of manure produced on the farm #beb1 note ,fermentation of farmyard manure-- ,action of micro-organic life in producing fermentation #bee ,two classes of bacteria active in this work1 aerobies and anaerobies #bee ,conditions influencing fermentation-- ,temperature #bef ,openness to the air #bef ,dampness #beg ,composition of manure #beg ,products of fermentation #beg ,analyses of farmyard manure-- ,dr ,voelcker's experiments #bei ,variation in composition #bei ,amounts of moisture1 organic matter 7containing nitrogen71 and mineral matter #bfj ,its manurial value compared with nitrate of soda1 sulphate of ammonia1 and superphosphate #bfj ,comparison of fresh and rotten manure-- ,the nature and amount of loss sustained in the process of rotting #bfa ,ought manure to be applied fresh or rotten8 #bfb ,relative merits of covered and uncovered manure-heaps #bfc ,methods of application of farmyard manure to the field-- ,merits and demerits of the different methods #bfe ,setting it out in heaps #bfe ,spreading it broadcast1 and letting it lie #bff ,ploughing it in immediately #bfg ,value and function of farmyard manure-- ,as a supplier of the necessary elements of plant-food #bfh ,as a universal manure #bfi ,proportion in which nitrogen1 phosphoric acid1 and potash are required by crops #bfi ,proportion in which they are present in farmyard manure #bgj ,farmyard manure poor in nitrogen #bgj ,lawes' and ,gilbert's experiments #bga ,how it may be best reinforced by the use of artificials #bga ,indirect value of farmyard manure as a supplier of humus to the soil #bgc ,its influence on soil-texture #bgc ,its influence in setting free inert fertilising matter in the soil #bgd ,rate at which farmyard manure ought to be applied #bge ,lasting nature of farmyard manure #bgf ,its economic value #bgf ,,appendix ,,to ,,chapter ,,vii4 ,,note ,i4 ,difference in amount of excreta voided for food consumed #bgi ,,ii4 ,solid excreta voided by sheep1 oxen1 and cows #bgi ,,iii4 ,urine voided by sheep1 oxen1 and cows #bhj ,,iv4 ,percentage of food voided in the solid and liquid excrements #bha ,v4 ,pig excrements #bha ,,vi4 ,manurial constituents in #ajjj parts of ordinary foods #bhb ,,vii4 ,analyses of stable-manure1 made respectively with peat-moss litter and wheat-straw #bhc ,,viii4 ,analyses of bracken #bhc ,,ix4 ,analyses of horse-manure #bhc ,x4 ,the nature of the chemical reactions of ammonia fixers #bhd ,,xi4 ,analyses of cow-manure #bhf ,,xii4 ,composition of fresh and rotten farmyard manure #bhf ,,xiii4 ,comparison of fresh and rotten manure #bhh ,,xiv4 ,lord ,kinnaird's experiments #bhi ,,xv4 ,drainings of manure-heaps #bij ,,xvi4 ,amounts of potash and phosphoric acid removed by rotation from a ,prussian morgen 74#fca acre7 #bij ,,xvii4 ,composition of farmyard manure 7fresh7 #bia ,,xviii4 ,the urine 7quantity voided7 #bia ,,chapter ,,viii4--,,guano4 ,importance in agriculture #bic ,influence on ,british farming #bid ,influence of guano not wholly good #bie ,value of guano as a manure #bif ,origin and occurrence of guano #big ,variation in composition of different guanos #bii ,i4 ,nitrogenous guano-- 7a7 ,peruvian guano #cjj ,different deposits of ,peruvian guano #cja ,appearance1 colour1 and nature of ,peruvian guano #cjc ,composition of ,peruvian guano #cjd 7b7 ,other nitrogenous manures3 ,angamos1 ,ichaboe #cjf ,,ii4 ,phosphatic guanos-- ,occurrence of phosphatic guanos #cjh ,inequality in composition of phosphatic guanos #cji ,dissolved phosphatic guano #caj ,equalised or rectified guano #caa ,the action of phosphatic guanos as manures #cab ,proportion of fertilising constituents in guano #cad ,mode of application of guanos #cae ,quantity of guano to be used #cag ,adulteration of guano #cah ,so-called guanos-- ,fish-guano #cbj ,value of fish-guano #cbb ,meat-meal guano #cbd ,value of meat-meal guano #cbd ,bat guano #cbe ,pigeon and fowl dung #cbe ,,appendix ,,to ,,chapter ,,viii4 ,,note ,i4 ,peruvian guano imported into ,united ,kingdom1 #ahfe-ahic #cbg ,,ii4 ,guano deposits of the world #cbg ,,iii4 ,composition of concretionary nodules #cbh ,,iv4 ,table showing gradual deterioration of ,peruvian guano1 #ahfg-ahha #cbi ,v4 ,composition of different guanos #cbi ,,vi4 ,liebig's theory as to the action of oxalic acid in guano #ccj ,,vii4 ,analyses of dung of fowls1 pigeons1 ducks1 and geese #cca ,,chapter ,,ix4--,,nitrate ,,of ,,soda4 ,amount of exports #ccb ,date of discovery of nitrate deposits #ccc ,the origin of nitrate deposits #ccd ,forbes and ,darwin on the theory of their origin #cce ,source of nitric acid in nitrate of soda #ccg ,guano theory of origin of nitrate of soda #ccg ,nitric acid in nitrate of soda probably derived from sea-weed #cci ,appearance of nitrate-fields #cdj ,the method of mining the nitrate of soda #cda ,composition of caliche #cdb ,extent of the nitrate deposits #cdb ,composition and properties of nitrate of soda #cdc ,nitrate applied as a top-dressing #cdd ,nitrate of soda encourages deep roots #cdd ,is nitrate of soda an exhausting manure8 #cde ,crops for which nitrate of soda is suited #cdf ,method of application of nitrate of soda #cdg ,importance of having a sufficiency of other fertilising constituents #cdh ,conclusions drawn #cdi ,,appendix ,,to ,,chapter ,,ix4 ,total shipments from ,south ,america1 #ahcj-ahic #cea ,total imports into ,europe and ,united ,kingdom1 #ahgc-ahib #cea ,,chapter ,x4--,,sulphate ,,of ,,ammonia4 ,value of ammonia as a manure #ceb ,sources of sulphate of ammonia #cec ,ammonia from gas-works #cec ,other sources #ced ,composition1 c41 of sulphate of ammonia #cee ,application of sulphate of ammonia #cef ,,appendix ,,to ,,chapter ,x4 ,production of sulphate of ammonia in ,united ,kingdom1 #ahgj-ahib #ceh ,,chapter ,,xi4--,,bones4 ,early use of bones #cei ,different forms in which bones are used #cfj ,composition of bones #cfb ,the organic matter of bones #cfc ,the inorganic matter of bones #cfc ,treatment of bones #cfd ,action of bones #cfe ,dissolved bones #cfh ,crops suited for bones #cfh ,bone-ash #cfi ,bone-char or bone-black #cfi ,,appendix ,,to ,,chapter ,,xi4 ,,note ,i4 ,analysis of bone-meal #cga ,,ii4 ,analysis of dissolved bones #cga ,,iii4 ,composition of bone-ash #cgb ,,iv4 ,composition of bone-char #cgb ,,chapter ,,xii4--,,mineral ,,phosphates4 ,coprolites #cgc ,canadian apatite or phosphorite #cgd ,estremadura or ,spanish phosphates #cge ,norwegian apatite #cgf ,charlestown or ,south ,carolina phosphate #cgf ,belgian phosphate #cgg ,somme phosphate #cgh ,florida phosphate #cgh ,lahn phosphate #cgi ,bordeaux or ,french phosphate #cgi ,algerian phosphate #cgi ,crust guanos #cgi ,value of mineral phosphates as manures #chj ,,appendix ,,to ,,chapter ,,xii4 ,imports of phosphates #cha ,,chapter ,,xiii4--,,superphosphates4 ,discovery of superphosphate by ,liebig #chb ,manufacture of superphosphate #chc ,nature of the reaction taking place #che ,phosphates of lime #che ,reverted phosphate #chi ,value of reverted phosphate #cia ,composition of superphosphates #cia ,action of superphosphates #cib ,action of superphosphate sometimes unfavourable #cie ,application of superphosphate #cie ,value of insoluble phosphates #cif ,rate at which superphosphate is applied #cig ,,appendix ,,to ,,chapter ,,xiii4 ,,note ,i4 ,the formulae1 and molecular and percentage composition1 of the different phosphates #cih ,,ii4 ,reactions of sulphuric acid and phosphate of lime #cih ,,iii4 ,table for conversion of soluble phosphate into insoluble phosphate #cii ,,iv4 ,action of iron and alumina in causing reversion #cii ,v4 ,relative trade values of phosphoric acid in different manures #djj ,,chapter ,,xiv4--,,thomas-,,phosphate ,,or ,,basic ,,slag4 ,its manufacture #dja ,not at first used #djc ,discovery of its value as a manure #djc ,composition of basic slag #djd ,processes for preparing slag #djf ,solubility of basic slag #djh ,darmstadt experiments with basic slag #daj ,results of other experiments #dac ,soils most suited for slag #dad ,rate of application #dad ,method of application #daf ,,appendix ,,to ,,chapter ,,xiv4 ,analysis of basic slag #dag ,,chapter ,,xv4--,,potassic ,,manures4 ,relative importance #dah ,scottish soils supplied with potash #dai ,sources of potassic manures #dai ,stassfurt potash salts #dbj ,relative merits of sulphate and muriate of potash #dba ,application of potash manures #dbb ,soils and crops suited for potash manures #dbc ,rate of application #dbc ,,chapter ,,xvi4--,,minor ,,artificial ,,manures4 ,scutch #dbg ,shoddy and wool-waste #dbg ,soot #dbh ,,chapter ,,xvii4--,,sewage ,,as ,a ,,manure4 ,irrigation #dca ,effects of continued application of sewage #dcc ,intermittent irrigation #dcd ,crops suited for sewage #dcd ,treatment of sewage by precipitation1 c4 #dcf ,value of sewage sludge #dci ,,chapter ,,xviii4--,,liquid ,,manure #ddb ,,chapter ,,xix4--,,composts4 ,farmyard manure a typical compost #ddf ,other composts #ddg ,,chapter ,,xx4--,,indirect ,,manures4 ,lime #ddi ,antiquity of lime as a manure #ddi ,action of lime #ddi ,lime a necessary plant-food #dej ,lime of abundant occurrence #deb ,lime returned to the soil in ordinary agricultural practice #deb ,different forms of lime #dec ,caustic lime #dec ,lime acts both mechanically and chemically #dee ,i4 ,mechanical functions of lime #dee ,action on soil's texture #dee ,lime renders light soils more cohesive #deg ,,ii4 ,chemical action of lime #deg ,,iii4 ,biological action of lime #dei ,action of lime on nitrogenous organic matter #dfj ,recapitulation #dfa ,,chapter ,,xxi4--,,indirect ,,manures--,,gypsum1 ,,salt1 ,,etc4 ,gypsum #dfb ,mode in which gypsum acts #dfb ,salt #dfe ,antiquity of the use of salt #dfe ,nature of its action #dfe ,salt not a necessary plant-food #dff ,can soda replace potash8 #dff ,salt of universal occurrence #dfg ,special sources of salt #dfh ,the action of salt #dfh ,mechanical action on soils #dgj ,solvent action #dgj ,best used in small quantities along with manures #dgb ,affects quality of crop #dgb ,rate of application #dgc ,,chapter ,,xxii4--,,the ,,application ,,of ,,manures4 ,influence of manures in increasing soil-fertility #dgd ,influence of farmyard manure on the soil #dge ,farmyard manure v4 artificials #dgf ,farmyard manure not favourable to certain crops #dgg ,conditions determining the application of artificial manures #dgg ,nature of the manure #dgh ,nitrogenous manures #dgh ,phosphatic manures #dhj ,potash manures #dhj ,nature of soil #dha ,nature of previous manuring #dhb ,nature of the crop #dhc ,amounts of fertilising ingredients removed from the soil by different crops #dhd ,capacity of crops for assimilating manures #dhf ,difference in root-systems of different crops #dhh ,period of growth #dhi ,variation in composition of crops #dij ,absorption of plant-food #dij ,fertilising ingredients lodge in the seed #dia ,forms in which nitrogen exists in plants #dia ,bearing of above on agricultural practice #dib ,influence of excessive manuring of crops #dib ,,chapter ,,xxiii4--,,manuring ,,of ,,the ,,common ,,farm ,,crops4 ,cereals #dic ,especially benefited by nitrogenous manures #did ,power of absorbing silicates #did ,barley #die ,period of growth #die ,most suitable soil #dif ,farmyard manure not suitable #dig ,importance of uniform manuring of barley #dig ,norfolk experiments on barley #dig ,proportion of grain to straw #dih ,wheat #dii ,rothamsted experiments #ejj ,continuous growth #ejj ,flitcham experiments #ejj ,oats #eja ,a very hardy crop #ejb ,require mixed nitrogenous manuring #ejb ,arendt's experiments #ejc ,avenine #ejc ,quantities of manures #ejd ,grass #ejd ,effect of manures on herbage of pastures #eje ,influence of farmyard manure #ejf ,influence of soil and season on pastures #ejg ,manuring of meadow land #ejh ,bangor experiments #ejh ,norfolk experiments #eji ,manuring of permanent pastures #eji ,roots #eaj ,influence of manure on composition #eab ,nitrogenous manures increase sugar #eab ,amount of nitrogen recovered in increase of crop #eac ,norfolk experiments #eac ,manure for swedes #ead ,highland ,society's experiments #eae ,manuring for rich crops of turnips #eaf ,experiments by the author on turnips #eaf ,potatoes #eag ,highland ,society's experiments #eah ,the ,rothamsted experiments #eai ,effect of farmyard manure #ebj ,manuring of potatoes in ,jersey #eba ,the influence of manure on the composition #eba ,leguminous crops #ebb ,leguminous plants benefit by potash #ebc ,nitrogenous manures may be hurtful #ebc ,clover sickness #ebd ,alternate wheat and bean rotation #ebd ,beans #ebe ,manure for beans #ebe ,relative value of manurial ingredients #ebf ,gypsum as a bean manure #ebf ,effect of manure on composition of crop #ebg ,peas #ebg ,hops #ebh ,cabbages #ebh ,,appendix ,,to ,,chapter ,,xxiii4 ,experiments on bean-manuring #ecj ,,chapter ,,xxiv4--,,on ,,the ,,method ,,of ,,application1 ,,and ,,on ,,the ,,mixing ,,of ,,manures4 ,equal distribution of manures #eca ,mixing manures #ecb ,risks of loss in mixtures #ecc ,loss of ammonia #ecc ,effects of lime on ammonia #ece ,loss of nitric acid #ecf ,reversion of phosphates #ecg ,manurial ingredients should be applied separately #ech ,,chapter ,,xxv4--,,on ,,the ,,valuation ,,and ,,analysis ,,of ,,manures4 ,value of chemical analysis #eci ,interpretation of chemical analysis #eci ,nitrogen #edj ,phosphoric acid #eda ,importance of mechanical condition of phosphate #edb ,potash #edb ,other items in the chemical analysis of manures #edc ,fertilisers and ,feeding ,stuffs ,act #edc ,different methods of valuing manures #edd ,unit value of manurial ingredients #edd ,intrinsic value of manures #ede ,field experiments #ede ,educational value of field experiments #edg ,value of manures deduced from experiments #edh ,value of unexhausted manures #edi ,potential fertility of a soil #edi ,tables of value of unexhausted manures4 #eea ,,appendix ,,to ,,chapter ,,xxv4 ,,note ,i4 ,factors for calculating compounds from manurial ingredients #eec ,,ii4 ,units for determining commercial value of manures and cash prices of manures #eed1 #eee ,,iii4 ,manurial value of nitrogen and potash in different substances #eef ,,iv4 ,comparative manurial value of different forms of nitrogen and potash #eeg ,v4 ,lawes' and ,gilbert's tables for calculating unexhausted value of manures #eei ,,chapter ,,xxvi4--,,the ,,rothamsted ,,experiments4 ,nature of experiments on crops and manures #efa ,soil of ,rothamsted #efa ,table ,i4 ,list of ,rothamsted field experiments #efb ,wheat experiments-- ,unmanured plots #efb ,wheat grown continuously on same land 7unmanured7 #efb ,table ,,ii4 ,results of first eight years #efb ,table ,,iii4 ,results of subsequent forty years #efb ,table ,,iv4 ,wheat grown continuously with farmyard manure 7#ad tons per annum7 #efd ,table ,v4 ,wheat grown continuously with artificial manures #efe ,table ,,vi4 ,experiments on the growth of barley1 forty years1 #aheb-ia #eff ,table ,,vii4 ,experiments on the growth of oats1 #ahfi-gh #efg ,table ,,viii4 ,experiments on root crops--,swedish turnips #efh1 #efi ,table ,,ix4 ,experiments on mangel-wurzel #efh1 #efi ,table ,x4 ,experiments with different manures on permanent meadow-land1 thirty-six years1 #ahef-ia #egj ,table ,,xi4 ,experiments on the growth of potatoes--average for five seasons1 #ahgf-hj #ega ,table ,,xii4 ,experiments on growth of potatoes 7continued7-- average for twelve seasons1 #ahha-ib #egb 99 99 99 99 99 ,,index #egc ,,part ,i4 ,,historical ,,introduction ,,manures ,,and ,,the ,,principles ,,of ,,manuring4 ,,historical ,,introduction4 ,agricultural ,chemistry1 like most branches of natural science1 may be said to be entirely of modern growth4 ,while it is true we have many old speculations on the subject1 they can scarcely be said to possess much scientific value4 ,the great questions which had first to be solved by the agricultural chemist were1--,what is the food of plants8 and1--,what is the source of that food8 ,the second of these two questions more easily admitted of answer than the first4 ,the source of plant-food could only be the atmosphere or the soil4 ,as the composition of the atmosphere1 however1 was not discovered till the close of last century1 and the chemistry of the soil is a question which is still requiring much work ere we shall be in possession of anything like a full knowledge of it1 it will be at once obvious that the very fundamental conditions for a solution of the question were awanting4 ,the beginning1 then1 of a true scientific agricultural chemistry may be said to date from the brilliant discoveries associated with the names of ,priestley1 ,scheele1 ,lavoisier1 ,cavendish1 and ,black--that is1 towards the close of last century4 ,early ,theories on ,source of ,plant-food4 ,while this is so1 and while we must regard the early attempts made towards solving this question as being1 for the most part1 of little scientific value1 it is not without interest1 from the historical point of view1 to glance briefly at some of these old interesting speculations4 ,the ,aristotelian doctrine1 regarding the possibility of dividing matter into the so-called four primary elements1 fire1 air1 earth1 and water1 which obtained in one form or another till the birth of modern chemistry1 had naturally an important influence on these early theories4 ,van ,helmont's ,theory4 ,among the earliest and most important attempts made to solve the problem of plant-growth was that by ,jean ,baptiste ,van ,helmont1 one of the best known of the alchemists1 who flourished about the beginning of the seventeenth century4 ,van ,helmont believed that he had proved by a conclusive experiment that all the products of vegetables were capable of being generated from water4 ,the details of this classical experiment were as follows3-- ,he took a given weight of dry soil--#bjj lb4--and into this soil he planted a willow-tree that weighed #e lb41 and he watered this carefully from time to time with pure rain-water1 taking care to prevent any dust or dirt falling on to the earth in which the plant grew4 ,he allowed this to go on growing for five years1 and at the end of that period1 thinking his experiment had been conducted sufficiently long1 he pulled up his tree by the roots1 shook all the earth off1 dried the earth again1 weighed the earth and weighed the plant4 ,he found that the plant now weighed #afi lb4 #c ounces1 whereas the weight of the soil remained very nearly what it was--about #bjj lb4 ,it had only lost #b ounces in weight4#a ,the conclusion1 therefore1 come to by ,van ,helmont was that the source of plant-food was water4#b ,digby's ,theory4 ,some fifty years later an extremely interesting book was published bearing the following title3 ',a ,discourse concerning the ,vegetation of ,plants1 spoken by ,sir ,kenelm ,digby1 at ,gresham ,college1 on the #bc;d of ,january #affj4 7,at a meeting of the ,society for promoting ,philosophical ,knowledge by ,experiments4 ,london3 ,printed for ,john ,williams1 in ,little ,britain1 over against ,st ,botolph's ,church1 #affi47' ,the author attributes plant-growth to the influence of a balsam which the air contains4 ,this book is especially interesting as containing the earliest recognition of the value of saltpetre as a manure4 ,the following is an extract from this interesting old work3-- ,the sickness1 and at last the death of a plant1 in its natural course1 proceeds from the want of that balsamick saline juice2 which1 ,i have said1 makes it swell1 germinate1 and augment itself4 ,this want may proceed either from a destitution of it in the place where the plant grows1 as when it is in a barren soil or bad air1 or from a defect in the plant itself1 that hath not vigour sufficient to attract it1 though it be within the sphere of it2 as when the root has become so hard1 obstructed and cold1 as that it hath lost its vegetable functions4 ,now1 both these may be remedy'd1 in a great measure1 by one and the same physick4444 ,the watering of soils with cold hungray springs doth little good2 whereas muddy saline waters brought to overflow a piece of ground enrich it much4 ,but above all1 well-digested dew makes all plants luxuriate and prosper most4 ,now what may it be that endues these liquors with such prolifick virtue8 ,the meer water which is common to them all1 cannot be it2 there must be something else enclosed within it1 to which the water serves but for a vehicle4 ,examine it by spagyric art1 and you will find that it is nothing else than a nitrous salt1 which is dilated in the water4 ,it is this salt which gives foecundity to all things3 and from this salt 7rightly understood7 not only all vegetables1 but also all minerals draw their origine4 ,by the help of plain salt-peter1 dilated in water and mingled with some other fit earthy substance1 that may familiarize it a little with the corn into which ,i endeavoured to introduce it1 ,i have made the barrenest ground far out-go the richest1 in giving a prodigiously plentiful harvest4 ,i have seen hemp-seed soaked in this liquor1 that hath in due time made such plants arise1 as1 for the tallness and hardness of them1 seemed rather to be coppice-wood of fourteen years' growth at least1 than plain hemp4 ,the fathers of the ,christian doctrine at ,paris still keep by them for a monument 7and indeed it is an admirable one7 a plant of barley consisting of #bdi stalks1 springing from one root or grain of barley2 in which they counted above #ah1jjj grains or seeds of barley4 ,but do you think that it is barely the salt-peter1 imbibed into the seed or root1 which causeth this fertility8 no3 that would be soon exhausted and could not furnish matter to so vast a progeny4 ,the salt-peter there is like a magnet1 which attracts a like salt which foecundates the air1 and gave cause to the ,cosmopolite to say there is in the air a hidden food of life4#c ,duhamel and ,hales4 ,the names of the ,french writer1 ,duhamel1 and of the ,english1 ,stephen ,hales1 may be mentioned in passing as authors of works bearing on the question of vegetable physiology4 ,both of these writers flourished about the middle of the eighteenth century4 ,the writings of the former contained much valuable information on the effects of grafting1 motion of sap1 and influence of light on vegetable growth1 and also the results of experiments which the author had carried out on the influence of treating plants with certain substances4 ',statical ,essays1 containing ,vegetable ,staticks2 or an ,account of some ,statical ,experiments on the ,sap of ,vegetables1 by ,stephen ,hales1 ,d4,d4' 7#b vols471 was published in ,london in #agch2 and contained1 as will be seen from its title1 records of experiments of very much the same nature as those of ,duhamel4 ,jethro ,tull's ,theory4 ,some reference may be made to a theory which created a considerable amount of interest when it was first published--viz41 that of ,jethro ,tull4 ,the chief value of ,tull's contribution to the subject of agricultural science was1 that he emphasised the importance of tillage operations by putting forward a theory to account for the fact1 universally recognised1 that the more thoroughly a soil was tilled1 the more luxuriant the crops would be4 ,as ,tull's theory had a very considerable influence in stirring up interest in many of the most important problems in agricultural chemistry1 and as it contained in itself much1 the value of which we have only of late years come to understand1 a brief statement of this theory may not be without interest4 ,according to ,tull the food of plants consists of the particles of the soil4 ,these particles1 however1 must be rendered very minute before they become available for the plant1 which absorbs them by means of its rootlets4 ,this pulverisation of the soil goes on in nature independently of the farmer1 but only very slowly1 and the farmer has therefore to hasten it on by means of tillage operations4 ,the more efficiently these operations are carried on1 the more abundant will the supply of plant-food be rendered in the soil4 ,he consequently introduced and advocated the system of horse-hoe husbandry4 ,this theory1 he informs us1 was suggested to him by the custom1 which he had noticed on the ,continent1 of growing vines in rows1 and hoeing the intervals between these rows from time to time4 ,the excellent results which followed this mode of cultivation induced him to adopt it in ,england for his farm crops4 ,he accordingly sowed his crops in rows or ridges1 wide enough apart to admit of thorough tillage of the intervals by ploughing as well as by hand-hoeing4 ,this he continued until the plant had reached maturity4 ,as to the exact width of the interval most suitable1 he made a large number of experiments4 ,at first1 in the cultivation of wheat1 he made this interval six feet wide2 but latterly he adopted an interval of lesser width1 that finally arrived at being between four and five feet4 ,he likewise experimented on each separate ridge as to which was the best number of rows of wheat to be sown1 latterly adopting1 as most convenient1 two rows at ten inches apart4 ,the great success which he met with in this system of cultivation induced him to publish the results of his experiments in his famous work1 ',horse-,hoeing ,husbandry4' ,while ,tull's theory was based on principles at heart thoroughly sound1 he was carried away by his personal success into drawing unwarrantable deductions4 ,thus he came to the conclusion that rotation of crops was unnecessary1 provided that a thorough system of tillage was carried out4 ,manures also1 according to him1 might be entirely dispensed with under his system of cultivation1 for the true function of all manures is to aid in the pulverisation of the soil by fermentation4 ,the first really valuable scientific facts contributed to the science were made by ,priestley1 ,bonnet1 ,ingenhousz1 and ,senebier4 ,discovery of the ,source of ,plants' ,carbon4 ,to ,charles ,bonnet 7#agbj-agic71 a ,swiss naturalist1 is due the credit of having made the first contribution to a discovery of very great importance--viz41 the true source of the carbon1 which we now know forms so large a portion of the plant-substance4 ,bonnet1 who had devoted himself to the question of the function of leaves1 noticed that when these were immersed in water bubbles were seen1 after a time1 to collect on their surface4 ,de la ,hire1 it ought to be pointed out1 had noticed this same fact about sixty years earlier4 ,it was left to ,priestley1 however1 to identify these bubbles with the gas he had a short time previously discovered--viz41 oxygen4 ,priestley had observed1 about this time1 the interesting fact that plants possessed the power of purifying air vitiated by the presence of animal life4#d ,the next step in this highly interesting and important discovery was taken by ,john ,ingenhousz 7#agcj-agii71 an eminent physician and natural philosopher4 ,in #aggi1 ,ingenhousz published a work in ,london entitled ',experiments on ,vegetables4' ,in it he gives the results of some important experiments he had made on the question already investigated by ,bonnet and ,priestley4 ,these experiments proved that plant-leaves only gave up their oxygen in the presence of sunlight4 ,in #aghb he published another work on ',the ,influence of the ,vegetable ,kingdom on the ,animal ,creation4'#e ,the source of the gas1 which ,bonnet had first noticed to be given off from plant-leaves1 ,priestley had identified as oxygen1 and ,ingenhousz had proved to be only given off under the influence of the sun's rays1 was finally shown by a ,swiss naturalist1 ,jean ,senebier#f 7#agdb-ahji71 to be the carbonic acid gas in the air1 which the plant absorbed and decomposed1 giving out the oxygen and assimilating the carbon4 ,publication of ,first ,english ,treatise on ,agricultural ,chemistry4 ,in #agie1 a book dealing with the relations between chemistry and agriculture was published4 ,this work was written by a ,scottish nobleman1 the ,earl of ,dundonald1 and possesses especial interest from the fact that it is the first book in the ,english language on agricultural chemistry4 ,the full title is as follows3 ',a ,treatise showing the ,intimate ,connection that subsists between ,agriculture and ,chemistry4' ,in his introduction the author says3 ,the slow progress which agriculture has hitherto made as a science is to be ascribed to a want of education on the part of the cultivators of the soil1 and to a want of knowledge1 in such authors as have written on agriculture1 of the intimate connection that subsists between the science and that of chemistry4 ,indeed1 there is no operation or process not merely mechanical that does not depend on chemistry1 which is defined to be a knowledge of the properties of bodies1 and of the effects resulting from their different combinations4 ,in quoting this passage ,professor ,s4 ,w4 ,johnson remarks3#g ,earl ,dundonald could not fail to see that chemistry was ere long to open a splendid future for the ancient art that had always been and always will be the prime supporter of the nations4 ,but when he wrote1 how feeble was the light that chemistry could throw upon the fundamental questions of agricultural science6 ,the chemical nature of the atmosphere was then a discovery of barely twenty years' standing4 ,the composition of water had been known but twelve years4 ,the only account of the composition of plants that ,earl ,dundonald could give was the following3 ',vegetables consist of mucilaginous matter1 resinous matter1 matter analogous to that of animals1 and some proportion of oil4444 ,besides these1 vegetables contain earthy matters1 formerly held in solution in the newly-taken-in juices of the growing vegetables4' ,to be sure1 he explains by mentioning in subsequent pages that starch belongs to the mucilaginous matter1 and that on analysis by fire vegetables yield soluble alkaline salts and insoluble phosphate of lime4 ,but these salts1 he held1 were formed in the process of burning1 their lime excepted2 and the fact of their being taken from the soil and constituting the indispensable food of plants1 his lordship was unacquainted with4 ,the gist of agricultural chemistry with him was1 that plants 'are composed of gases with a small proportion of calcareous matter2 for although this discovery may appear to be of small moment to the practical farmer1 yet it is well deserving of his attention and notice4' ,de ,saussure4 ,the year #ahjd witnessed the publication of by far the most important contribution made to the science up till this time4 ,this was ',recherches ,chimique sur la ,vegetation1' by ,theodore de ,saussure1 one of the most illustrious agricultural chemists of the century4 ,de ,saussure was the first to draw attention to the mineral or ash constituents of the plant2 and thus anticipate1 to a certain extent1 the subsequent famous mineral theory of the great ,liebig4 ,the ,french chemist maintained that these ash ingredients were essential2 and that without them plant-life was impossible4 ,he also adduced fresh experiments of his own in support of the theory1 based on the experiments of ,bonnet1 ,priestley1 ,ingenhousz1 and ,senebier1 that plants obtain their carbon from the carbonic acid gas in the air1 under the influence of the sunlight4 ,he was of opinion that the hydrogen and oxygen of the plant were1 probably1 chiefly derived from water4 ,he showed that by far the largest portion of the plant's substance was derived from the air and from water1 and that the ash portion was alone derived from the soil4 ,to ,saussure we owe the first definite statement on the different sources of the plant's food4 ,it may be said that the lapse of nearly a century has shown his views to be1 in the main1 correct4 ,source of ,plant-nitrogen4 ,there was one question1 which1 even at that remote period in the history of the subject1 engaged the attention of agricultural chemists--viz41 the question of the source of the plant's nitrogen--a question which may be fitly described at the present hour as still the burning question of agricultural chemistry4#h ,as soon as it was discovered that nitrogen was a constituent of the plant's substance2 speculations as to its source were indulged in4 ,the fact that the air furnished an unlimited storehouse of this valuable element1 and the analogy of the absorption of carbon 7from the same source by plant-leaves71 naturally suggested to the minds of early inquirers that the free nitrogen of the air was the source of the plant's nitrogen4 ,as1 however1 no direct experiments could be adduced to prove this theory1 and as1 moreover1 nitrogen was found in the soil1 and seemed to be a necessary ingredient of all fertile soils1 the opinion that the soil was the only source gradually supplanted the older theory4 ,little value1 however1 must be attached to these early theories1 as they can scarcely be said to have been based on experiments of serious value4 ,indeed it may be safely affirmed1 in the light of subsequent experiments1 that it was impossible for this question to be decided at this early period1 from the fact that analytical apparatus1 of a sufficiently delicate nature1 was then wholly unknown4 ,indeed it is only within the last few years that it has been possible to carry out experiments which may be regarded as at all crucial4 ,a short sketch of the development of our knowledge of the relation of nitrogen to the plant will be given further on4 ,sir ,humphry ,davy's ,lectures4 ,a series of lectures on agricultural chemistry1 delivered by ,sir ,humphry ,davy during the years #ahjb-ahab1 for the ,board of ,agriculture1 and subsequently published in book form in the year #ahac1i affords us an opportunity of gauging1 pretty accurately1 the state of knowledge on the subject at the time4 ,position of ,agricultural ,chemistry at beginning of ,century4 ,in his opening lecture ,davy says3 ,agricultural chemistry has not yet received a regular and systematic form4 ,it has been pursued by competent experimenters for a short time only4 ,the doctrines have not as yet been collected into any elementary treatise1 444 and1 he adds1 ,i am sure you will receive with indulgence the first attempt made in this country to illustrate it by a series of experimental demonstrations4 ,he further on remarks3 ,it is evident that the study of agricultural chemistry ought to be commenced by some general inquiries into the composition and nature of material bodies1 and the law of their changes4 ,the surface of the earth1 the atmosphere1 and the water deposited from it1 must either together1 or separately1 afford all the principles concerned in vegetation1 and it is only by examining the chemical nature of these principles that we are capable of discovering what is the food of plants1 and the manner in which this food is supplied and prepared for their nourishment4 ,davy goes on further to say3 ,no general principles can be laid down respecting the comparative merits of the different systems of cultivation and the various systems of crops adopted in different districts1 unless the chemical nature of the soil1 and the physical circumstances to which it is exposed1 are fully known4 ,he recognises the enormous importance of experiments4 ,nothing is more wanting in agriculture than experiments1 in which all the circumstances are minutely and scientifically detailed4 ,in dealing with the composition of plants he says3 ,it is evident that the most essential vegetable substances consist of hydrogen1 carbon1 and oxygen1 in different proportions1 generally alone2 but in some few cases combined as carbon and nitrogen4 ,the acids1 alkalies1 earths1 metallic oxides1 and saline compounds1 though necessary in the vegetable economy1 must be considered as of less importance1 particularly in their relation to agriculture1 than the other principles4 ,further on3 ,it will be asked1 ,are the pure earths in the soil merely active as mechanical or indirect chemical agents1 or do they actually afford food to the plant8 ,this question he answers by saying that water1 and the decomposing animal and vegetable matter existing in the soil1 constitute the true nourishment of plants2 and as the earthy parts of the soil are useful in retaining water1 so as to supply it in the proper proportion to the roots of the vegetables1 so they are likewise efficacious in producing the proper distribution of the animal or vegetable matter4 ,when equally mixed with it1 they prevent it from decomposing too rapidly2 and by their means the soluble parts are supplied in proper proportions4 ,value of ,davy's ,lectures4 ,the chief value of these lectures is due to the fact that they form the first attempt to connect in a systematic manner the various scattered facts1 up to that time ascertained1 and to interpret their bearing on agricultural practice4 ,we have in them1 it is true1 a strange mixture of facts belonging rather to botany and physiology than to agricultural chemistry2 still they undoubtedly furnished a great impetus to inquiry1 and at the same time they did much to popularise the science4 ,but not merely did ,davy summarise and systematise the various results arrived at by others1 he also made many valuable contributions to the science himself4 ,the conclusions he drew from the results he obtained were1 no doubt1 in many cases false1 and in other cases exaggerated2 still the results possess a permanent interest4 ,he may be said to have worked out many of the most important physical or mechanical properties of a soil1 although exaggerating the importance of the influence of these properties on the question of fertility4#aj ,these experiments had to do with the heat- and water-absorbing powers of a soil4 ,he experimented on a brown fertile soil1 and a cold barren clay1 and found at what rate they lost heat4 ,nothing1 he says1 can be more evident than that the genial heat of the soil1 particularly in spring1 must be of the highest importance to the rising plant2 444 so that the temperature of the surface1 when bare and exposed to the rays of the sun1 affords at least one indication of the degree of the fertility4 ,again he says3 ,the power of soils to absorb water from air is much connected with fertility4444 ,i have compared the absorbent powers of many soils1 with respect to atmospheric moisture1 and ,i have always found it greatest in the most fertile soils2 so that it affords one method of judging of the productiveness of land4 ,where he erred was in overestimating the functions of the mechanical properties of a soil1 and in considering fertility to be due to them alone4 ,during the next thirty years or so1 little progress seems to have been made in the way of fresh experimentation4 ,boussingault4 ,in #ahcd1 ,boussingault1#aa the most distinguished ,french agricultural chemist of the century1 began that series of brilliant chemico-agricultural experiments on his estate at ,bechelbronn1 in ,alsace1 the results of which have added so much to agricultural science4 ,it was the first instance of the combination of science with practice1 of the institution of a laboratory on a farm2 a combination peculiarly fitted to promote the interests of agricultural science1 and an example which has been since followed with such magnificent results in the case of ,sir ,john ,lawes's famous ,rothamsted ,experiment ,station1 and other less known research stations4 ,boussingault's first paper appeared in #ahcf1 and was entitled1 ,the amount of nitrogen in different kinds of foods1 and on the equal value of foods founded on these data4 ,in the year following other papers were published on such subjects as the amount of gluten in different kinds of wheat2 on the meteorological considerations of how far various agricultural operations--such as extensive clearings of wood1 the draining of large swamps1 c4--influence of climate on a country2 and on experiments on the culture of the vine4 ,boussingault was the first observer to study the scientific principles underlying the system of rotation of crops4 ,in #ahch he published the results of some very elaborate experiments he had carried out on this subject4 ,he also was the first chemist to carry out elaborate experiments with a view to deciding the question of the assimilation by plants of free atmospheric nitrogen4 ,his first contribution to the subject was published in #ahch1 but can scarcely be regarded as possessing much scientific value1 except in so far as it stimulated further research4 ,some thirteen years later he returned to this question2 and during the years #ahea-ahee carried out most elaborate experiments1 the results of which1 until quite recently1 were generally regarded as having1 along with the experiments of ,messrs ,lawes1 ,gilbert1 and ,pugh1 definitely settled the question4#ab ,in #ahci ,boussingault was elected a member of the ,french ,institute1 an honour paid to him in recognition of his great services to agricultural chemistry4#ac ,the foregoing is a brief epitome of the history of the development of agricultural chemistry up to the year #ahdj1 the year which witnessed the publication of one of the most memorable works on the subject1 which has appeared during the present century--,liebig's first report to the ,british ,association1 a work which may be described as constituting an epoch in the history of the science4 ,liebig's position as an agricultural chemist was so prominent1 and his influence as a teacher so potent1 that a few biographical facts may not be out of place before entering upon an estimate of his work4 ,liebig4 ,liebig was born at ,darmstadt in the year #ahjc4 ,he was the son of a drysalter1 and early devoted himself to the study of chemistry in the only way at first at his disposal--viz41 in an apothecary's shop4 ,soon finding1 however1 his opportunities of study limited1 he left the apothecary's shop for the ,university of ,bonn4 ,he did not remain long at ,bonn1 but in a short time left that university for ,erlangen1 where he studied for some years1 taking his ,ph4,d4 degree in #ahbb4 ,his subsequent studies were carried on at ,paris under ,gay-,lussac1 ,thenard1 ,dulong1 and other distinguished chemists4 ,through the influence of ,a4 ,humboldt1 who was at that time in ,paris1 and whose acquaintance he was fortunate enough to make1 he was received into ,gay-,lussac's private laboratory4 ,in #ahbd--that is1 when he was only twenty-one years of age--he was appointed ,professor ,extraordinarius of ,chemistry at the ,university of ,giessen4 ,two years later he was appointed to the post of ,professor ,ordinarius--an appointment which he held for twenty-five years4 ,in #ahde he was created ,baron1 and in #aheb appointed ,professor at ,munich4 ,he died in #ahgc4 ,his ,first ,report to ,british ,association4 ,the report above referred to was made by ,liebig at the request of the ,chemical ,section of the ,british ,association4 ,it was read to a meeting of the ,association held in ,glasgow in #ahdj1 and was subsequently published in book form1 under the title of ',chemistry in its ,application to ,agriculture and ,physiology1' ,liebig's position1 past training and experience were such as to peculiarly fit him for the part of pioneer in the new science4 ,as ,sir ,j4 ,h4 ,gilbert has remarked1#ad ,in the treatment of his subject he not only called to his aid the previously existing knowledge directly bearing upon his subject1 but he also turned to good account the more recent triumphs of organic chemistry1 many of which had been won in his own laboratory4 ,in his dedication to the ,british ,association at the beginning of the book1 ,liebig says3 ,perfect agriculture is the true foundation of all trade and industry--it is the foundation of the riches of ,states4 ,but a rational system of agriculture cannot be formed without the application of scientific principles2 for such a system must be based on an exact acquaintance with the means of nutrition of vegetables1 and with the influence of soils and actions of manure upon them4 ,this knowledge we must seek from chemistry1 which teaches the mode of investigating the composition and of studying the characters of the different substances from which plants derive their nourishment4 ,his criticism of the ,humus ,theory4 ,the first subject which ,liebig discusses is the scientific basis of the so-called humus theory4 ,the humus theory seems to have been first promulgated by ,einhof and ,thaer towards the close of last century4 ,thaer held that humus was the source of plant-food4 ,he stated in his published writings that the fertility of a soil depended really upon its humus2 for this substance1 with the exception of water1 is the only source of plant-food4 ,de ,saussure1 however1 by his experiments--the results of which he had published in #ahjd--;had shown the fallacy of this humus theory2 and his statements had been further developed and substantiated by the investigations of the ,french chemist ,braconnot and the ,german chemist ,sprengel4 ,despite1 however1 the experiments of ,saussure1 ,braconnot1 and ,sprengel1 the belief that plants derived the carbonaceous portion of their substance from humus still seemed to be commonly held in #ahdj4 ,while ,liebig1 therefore1 can scarcely be said to have been the first to controvert the humus theory1 he certainly dealt it its death-blow4 ,he reasserted de ,saussure's conclusions1 and by some simple calculations showed very clearly that it was wholly untenable4 ,one of the most striking of the arguments he brought forward was the fact that the humus of the soil itself consisted of the decayed vegetable matter of preceding plants4 ,this being so1 how1 he asked1 could it be the original source of the carbon of plants8 ,to reason thus was simply to reason in a circle4 ,he pointed out1 further1 that the comparative insolubility of humus in water1 or even in alkaline solutions1 told against its acceptance as correct4 ,his ,mineral ,theory4 ,having thus controverted the humus theory1 he then goes on to deal with the question of the source of the various plant constituents4 ,in treating of the relation of the soil to the plant1 he puts forward his mineral theory4 ,it cannot be doubted that1 while the advance of science since ,liebig's time has induced us to considerably modify his mineral theory1 it contained the statement of one of the most important facts in the chemistry of plant physiology4 ,he was the first to fully estimate the enormous importance of the mineral portion of the plant's food1 and point the way to one of the chief sources of a soil's fertility4 ,up to this period the ash constituents had been generally considered to be of minor importance4 ,by emphasising the contrary opinion1 and insisting upon their essentialness to plant-life1 he gave to agricultural research a fresh impetus upon the right lines4 ,his statement of his mineral theory was in the main true1 but was not the whole truth4 ,de ,saussure1 as has already been pointed out1 to a certain extent1 anticipated ,liebig's mineral theory4 ,he was of the opinion that whatever might be the case with some of the mineral constituents of plants1 others were necessary1 inasmuch as they were always found in the ash4 ,of these he instanced the alkaline phosphates4 ,their small quantity does not indicate their inutility1 he sagaciously remarks4 ,sir ,humphry ,davy1 as has already been pointed out1 missed recognising the true importance of the ash constituents4 ,it was left to ,liebig1 then1 to restate the important doctrine of the essentialness of the mineral matter1 already implied to some extent by de ,saussure4 ,liebig says3 ,carbonic acid1 water1 and ammonia are necessary for the existence of plants1 because they contain the elements from which their organs are formed2 but other substances are likewise necessary for the formation of certain organs destined for special functions1 peculiar to each family of plants4 ,plants obtain these substances from inorganic nature4 ,while insisting on the importance of the mineral constituents1 he did so in a more or less general way not sufficiently distinguishing one mineral constituent from another4 ,as all plants contained certain organic acids1 and as these organic acids were nearly always found in a neutral state--i4e41 in combination with bases1 such as potash1 soda1 lime1 and magnesia--the plant must be in a position to take up sufficient of these alkaline bases to neutralise these acids4 ,hence the necessity of these mineral constituents in the soil4 ,according to him1 however1 the exact nature of the bases was a point of not so much importance4 ,he assumed1 in short1 as has been pointed out by ,sir ,j4 ,h4 ,gilbert1 a greater amount of mutual replaceability amongst the bases than can be now admitted4 ,passing on to a consideration of the difference of the mineral composition of different soils1 he attributes this to the difference in the rocks forming the soils4 ,weathering is the great agent at work in rendering available the otherwise locked-up stores of fertility4 ,he attributes the benefits of fallow exclusively to the increased supply of these incombustible compounds which were thus rendered available to the plant4 ,treating of this subject1 he says3 ,from the preceding part of this chapter 7in which he has been explaining weathering7 it will be seen that fallow is that period of culture when the land is exposed to progressive disintegration by the action of the weather1 for the purpose of liberating a certain quantity of alkalies and silica1 to be absorbed by future plants4 ,his ,theory of ,manures4 ,treating of manures1 he showed how the most important constituents of manures were potash and phosphates4 ,in the first edition of his work he also insisted on the value of nitrogen in manures1 condemning the want of precautions1 in the treatment of animal manures1 against loss of nitrogen4 ,in the later editions of his work he seems to have receded from that opinion1 and considered that there was no necessity for supplying nitrogen in manures1 since the ammonia washed down in rain was a sufficient source of all the nitrogen the plant required4 ,it was here that ,liebig went astray1 first in denying the importance of supplying nitrogen as a manure2 and secondly1 in overestimating the amount of ammonia washed down in rain1 which has subsequently been shown to be entirely inadequate to supply plants with the whole of their nitrogen4#ae ,his ,theory of ,rotation of ,crops4 ,in explaining the benefits of the rotation of crops1 ,liebig propounded a very ingenious theory1 but one which was largely of a speculative nature1 and which has since been shown to be unfounded on any scientific basis4 ,it was to the effect that one kind of crop excreted matters which were especially favourable to another kind of crop4 ,he did not say whether he considered such excretion positively injurious to the crop which excreted them2 but he inferred that what was excreted by the crop was what was not required1 and what could1 therefore1 be of little benefit to a crop of the same nature following it4 ,the second portion of ,liebig's report dealt with the processes of fermentation1 decay1 and putrefaction4 ,publication of ,liebig's ,second ,report to ,british ,association4 ,in #ahdb ,liebig contributed his second famous report to the ,british ,association1 subsequently published under the title of ',animal ,chemistry2 or1 ,organic ,chemistry in its ,applications to ,physiology and ,pathology4' ,the publication of this report created even greater interest than the publication of his first work4 ,in it he may be said to have contributed as much to animal physiology1 as1 in his first1 he did to agricultural chemistry4 ,his subsequent principal works on agricultural chemistry were--',principles of ,agricultural ,chemistry1' published in #ahee1 and ',on ,theory and ,practice in ,agriculture1' #ahef4 ,liebig's services to ,agricultural ,chemistry4 ,an attempt has been made to sketch in the very briefest manner some of the main points in ,liebig's teaching1 as contained in his famous report to the ,british ,association in #ahdj4 ,agricultural chemistry up till that year can scarcely be described as having a distinct existence as a branch of chemistry4 ,much valuable work1 it is true1 had already been done1 especially by his two great predecessors1 de ,saussure and ,boussingault2 but it was1 down to the year #ahdj1 a science made up of isolated facts4 ,liebig's genius formed it into an important branch of chemistry1 supplied the necessary connection between the facts1 and by a series of brilliant generalisations formed the principles upon which all subsequent advance has been built4 ,as has already been indicated1 ,liebig's chief claim to rank as the greatest agricultural chemist of the century does not rest upon the number or value of his actual researches1 but on the formative power he exercised in the evolution of the science4 ,his master-mind surveyed the whole field of agricultural chemistry1 and saw laws and principles where others saw simply a confusion of isolated1 and1 in many cases1 seemingly contradictory facts4 ,but great as the direct value of ,liebig's work was1 it may be questioned whether its indirect value was not even greater4 ,the publication of his famous work had the effect of giving a general interest to questions which up till then had possessed a special interest1 and that for comparatively few4 ,both on the ,continent and in ,england a very large amount of discussion took place regarding his various theories4 ,development of ,agricultural ,research in ,germany4 ,it was especially in ,germany1 however1 that ,liebig's work bore its greatest and most immediate fruit4 ,thanks to the great chemist1 the ,german ,government recognised the importance of forwarding scientific research by ,state aid4 ,agricultural ,departments were added to some of the universities1 largely at ,state expense1 while agricultural research stations were1 one after another1 instituted in different parts of the country4 ,the first of the agricultural research stations to be founded was the now famous one of ,moeckern1 near ,leipzig4 ,it was instituted in the year #ahea4 ,others followed1 until at the present day there are some seventy to eighty of these ,versuchs-,stationen scattered throughout ,germany1 all well equipped and doing excellent work4 ,some idea of the activity of the ,german stations may be inferred when it is stated that up to the year #ahgg the total number of papers embodying the results of their experiments published by them amount to over #bjjj4af ,to trace the development of agricultural chemistry1 subsequent to ,liebig's time1 in the way it has been done prior to the year #ahdj1 is no longer possible4 ,this is due to the enormous increase in the number of workers in the field1 as also to the overlapping nature of their work1 which renders a strict chronological record wellnigh an impossibility4 ,it will be better1 therefore1 to attempt to give a brief statement of our present knowledge on the subject1 naming the chief workers in the various departments of the subject4 ,the ,rothamsted ,experiments4 ,before doing so1 it is fitting that reference should be made to the work and experiments of two living ,english chemists1 who have done much to contribute to our knowledge in every branch of the science--viz41 ,sir ,john ,lawes1 ,bart41 and ,sir ,j4 ,h4 ,gilbert1 ,f4,r4,s4 ,the fame of the ,rothamsted experiments is now world-wide2 and no single experiment station has ever produced such an amount of important work as the magnificently equipped research station at ,rothamsted4 ,the ,rothamsted station may be said to date from #ahdc1 although ,sir ,john ,lawes was engaged in carrying out field experiments for ten years previous to that date4#ag ,in #ahdc ,sir ,john ,lawes associated with himself the distinguished chemist ,sir ,j4 ,h4 ,gilbert1 and the numerous papers since published have almost invariably borne the two names4 ,the expense of working the station has been borne entirely by ,sir ,john ,lawes himself2 who has further set aside a sum of ,l#ajj1jjj1 the ,laboratory1 and certain areas of land1 for the continuance of the investigations after his death4 ,the fields under experimentation amount to about fifty acres4 ,by a ,trust-deed1 which was signed on ,february #ad1 #ahhi1 ,sir ,john ,lawes has made over the ,rothamsted ,experimental ,station to the ,english nation1 to be managed by trustees4 ,it is impossible to enter1 in any detail1 into the nature and scope of the ,rothamsted experiments4#ah ,it may be stated that1 since the year #ahdg1 some eighty papers have been published on field experiments1 and experiments on vegetation2 while thirty papers have been published recording experiments on the feeding of animals4#ai ,what has all along characterised these valuable experiments has been their practical nature4 ,while their aim has been entirely scientific1 the scale of the experiments and the conditions under which they have been carried out1 have been such as to render them essentially technical experiments4 ,for this reason their results possess1 and will always possess1 a peculiar interest for every practical farmer4 ,the greatest services the ,rothamsted experiments have rendered agricultural chemistry have been the valuable contributions they have made to our knowledge of the function of nitrogen in agriculture2 its relation in its different chemical forms to plant-life2 and the sources of the nitrogen found in plants4 ,researches of a most elaborate nature have been carried out on what is still one of the most keenly debated questions of the present hour--viz41 the relation of the free nitrogen in the atmosphere to the plant4 ,of the very highest value also have been the elaborate researches of ,mr ,r4 ,warington1 ,f4,r4,s41 on the important question of ,nitrification1 which have been in course in the ,rothamsted ,laboratory for the last fifteen years1 and to which full reference will be made in the chapter on ,nitrification4 ,to the ,rothamsted experiments also we owe the refutation of ,liebig's mineral theory4 ,in fact it may safely be said that no experimenters in the field of agricultural chemistry have made more numerous or valuable contributions to the science than these illustrious investigators4 ,review of our present ,knowledge of ,agricultural ,chemistry4 ,some attempt may now be made to indicate briefly our present knowledge of the more important facts regarding plant physiology1 agronomy1 and manuring4 ,proximate ,composition of the ,plant4 ,the great advance made in the direction of the improvement of the accuracy of old analytical processes and the discovery of numerous new ones have furnished us with elaborate analyses of the composition of plants4 ,we now know that the plant-substance is made up of a large number of complex organic substances1 formed out of carbon1 hydrogen1 oxygen1 and nitrogen1#bj and that these substances form1 on an average1 about #ie per cent of the dry vegetable matter2 the other #e per cent being made up of mineral substances4 ,as to the source of these different substances1 our knowledge is1 on the whole1 pretty complete4 ,with regard to the carbon of green-leaved plants1 which amounts to from #dj to #ej per cent1 subsequent research has confirmed ,senebier and de ,saussure's conclusions1 that its source is the carbonic acid gas of the air4 ,the decomposition of the carbonic acid gas is effected by the leaves under the influence of sunlight4 ,that a certain quantity of carbon may be obtained from the carbonic acid absorbed by plant-roots1 is indeed probable4 ,especially during the early stages of plant-growth this source of carbon may be of considerable importance4 ,generally speaking1 however1 it may be said of all green-leaved plants1 that the chief source of their carbon is the carbonic acid gas in the atmosphere4 ,carbon ,fixation by ,plants4 ,the exact way in which this decomposition of carbonic acid gas is effected by the leaves is not yet clear4 ,it seems to be directly dependent1 in some way or other1 on the chlorophyll1 or green colouring matter4 ,this decomposition of carbonic acid1 and the fixation of the carbon by the plant with the formation of starch1 takes place only under the influence of sunlight4 ,during the night a reflex action takes place1 which is commonly known as respiration1 and which is exactly analogous to animal respiration4#ba ,the rate at which the fixation of carbon takes place depends on the strength of the sun's rays4 ,it seems to take place very rapidly under a strong tropical sun4#bb ,the action of sunlight on the absorption of carbon has been studied by a number of observers1 among others by ,sachs1 ,draper1 ,cloez1 ,gratiolet1 ,caillet1 ,prillieux1 ,lommel1 c4 ,action of ,light on ,plant-growth4 ,experiments made by several observers1 more especially ,pfeffer1 have shown that the yellow rays of the solar spectrum are the most potent in inducing this decomposition4 ,some interesting experiments have been carried out by different observers on the possibility of growing plants under the influence of artificial light4 ,while it would seem that the light from oil-lamps or gaslight is unable to promote growth1 except in very exceptional cases1 the electric light1 or other strong artificial light1 seems to be capable of taking the place of sunlight4 ,heinrich was the first to show that sunlight could be replaced by the magnesium light4 ,experiments with the electric light have been carried out by ,herve-,mangon in ,france and ,dr ,siemens in ,england4 ,the plants grown under the influence of the electric light were observed to be of a lighter green colour than those grown under normal conditions1 thus indicating a feebler growth2 in fact1 ,siemens was of the opinion that the electric light was about half as effective as daylight4#bc ,these experiments are interesting from an industrial point of view2 for it is conceivable that at some distant time electricity might be called to the aid of the agriculturist4 ,source of ,plants' ,oxygen4 ,with regard to the source of the oxygen1 which1 next to carbon1 is the element most largely present in the plant's substance--amounting to1 roughly speaking1 about #dj per cent--all evidence seems to indicate that it is chiefly derived from water1 which is also the source of the plant's hydrogen4 ,in addition to water1 carbonic acid and nitric acid may also furnish small quantities4 ,it has been pretty conclusively proved that the atmospheric oxygen1 while necessary to plant-growth1 and promoting the various chemical vital processes1 is not a direct source of the plant's oxygen4 ,the important function played by atmospheric oxygen in certain stages of the plant's growth has been long recognised4 ,malpighi1 nearly two hundred years ago1 observed that for the process of germination atmospheric air was necessary2 and shortly after the discovery of the composition of the air was made1 oxygen was identified as the important gas in promoting this process4 ,oxygen is also especially necessary during the period of ripening4 ,source of ,plants' ,hydrogen4 ,hydrogen1 which amounts to about #f per cent1 is1 as has already been pointed out1 chiefly derived from water4 ,it is possible that ammonia also may form a source4 ,source of ,plants' ,nitrogen4 ,when we come to treat of the source of the nitrogen1 which is found in the plant's substance to an extent varying from a fraction of a per cent to about #d per cent1 we enter on a much more debated question4 ,what is the source1 or1 what are the sources1 of plant-nitrogen8 is a question to the solution of which more time and more research have been devoted than to the solution of any other question connected with agricultural chemistry4 ,the most obvious source is the free nitrogen1 which forms four-fifths of the atmospheric air4 ,reference has already been made to this question4#bd ,priestley was the first of the long list of experimenters on this interesting question4 ,as far back as #agga he affirmed that certain plants had the power of absorbing free nitrogen2 and this opinion he supported by the results of certain experiments he had made on the subject4 ,eight years later1--viz41 in #aggi--;,ingenhousz further supported this conclusion1 and stated that all plants could absorb1 within the space of a few hours1 noticeable quantities of nitrogen gas4 ,the first to oppose this theory was de ,saussure1 who1 in #ahjd1 carried out experiments which showed that plants were unable to utilise free nitrogen4 ,subsequent experiments1 carried out by ,woodhouse and ,senebier1 supported de ,saussure's conclusions4 ,mention has already been made of ,boussingault's elaborate researches on the subject4#be ,his first experiments were carried out in #ahch4 ,he concluded that plants did not absorb free nitrogen4 ,georges ,ville was the first to reassert the older theory1 put forward by ,priestley and ,ingenhousz4 ,his opinion was founded on experiments he had carried out during the years #ahdi-eb4 ,the subject created so much interest at the time1 that a committee of the ,french ,academy--consisting of ,dumas1 ,regnault1 ,peligot1 ,chevreul1 and ,decaisne--were appointed to investigate ,ville's experiments4 ,the result of the investigation of the ,commission was to confirm ,ville's experiments4 ,it is a significant fact1 however1 that the plant experimented with by the ,commission was cress--a non-leguminous plant4 ,it has been commonly assumed that the results of recent experiments have confirmed ,ville's experiments4 ,it is only proper to point out that this is not a necessary inference4 ,the assimilation of free nitrogen by the leguminosae1 so far as modern research has revealed1 only takes place under the influence of micro-organic life4 ,ville's experiments1 however1 were supposed to be conducted under sterilised conditions4 ,in the meantime the results of ,boussingault's second series of experiments1 carried out between the years #ahea and #ahee1 were published1 and confirmed his earlier experiments4 ,the results of a large number of experiments subsequently carried out were in support of ,boussingault's conclusions4 ,among them may be mentioned ,mene1 ,harting1 ,gunning1 ,lawes1 ,gilbert and ,pugh1 ,roy1 ,petzholdt1 and ,bretschneider4 ,such an amount of overwhelming evidence might naturally have been regarded as conclusively proving that the free nitrogen of the air is not an available source of nitrogen to the plant4 ,the question1 however1 was not decided4 ,in #ahgf ,berthelot reopened it4 ,from experiments he had carried out1 he concluded that free nitrogen was fixed by various organic compounds1 under the influence of silent electric discharges4 ,in #ahhe he carried out further experiments1 from which he concluded that argillaceous soils had the power of fixing the free nitrogen of the atmosphere4 ,this they effected1 he was of opinion1 through the agency of micro-organisms4 ,schloesing has recently shown that this fixation of free nitrogen by soils is extremely doubtful4#bf ,the gain of nitrogen observed under such conditions can be explained by the absorption by the soil of combined nitrogen--viz41 ammonia--from the air4 ,berthelot's early experiments in #ahgf had the effect of stimulating a number of other experiments1 with the result that we now possess the solution of this long-debated and most important problem4 ,the names of the better known investigators on this subject1 in addition to ,berthelot's1 are those of ,hellriegel1 ,wilfarth1 ,deherain1 ,joulie1 ,dietzell1 ,frank1 ,emil von ,wolff1 ,atwater1 ,woods1 ,nobbe1 ,ward1 ,breal1 ,boussingault1 ,wagner1 ,schultz-,lupitz1 ,fleischer1 ,pagnoul1 ,schloesing1 ,laurent1 ,petermann1 ,pradmowsky1 ,beyrenick1 ,lawes1 and ,gilbert4 ,it is impossible to enter into the details of these most important experiments4 ,an attempt may be made1 instead1 briefly to epitomise them4 ,recent ,experiments on ,nitrogen question4 ,in the first place1 it may be asked1 ,how is it possible that the previous elaborate experiments1 published prior to #ahgf1 should now prove unreliable8 ,a satisfactory explanation may be found in the fact1 as ,lawes and ,gilbert have recently pointed out1 that the fixation of the free nitrogen by the plant1 or within the soil1 takes place1 if at all1 through the agency of electricity or of micro-organisms1 or of both4 ,the earlier experiments1 however1 were so arranged as to exclude the influence of either of those agencies4 ,the question has further been limited in its scope4 ,it is now supposed that only plants of the leguminous order have the power of drawing upon the free atmospheric nitrogen4 ,of the experiments above referred to1 those of ,hellriegel and ,wilfarth are the most striking and important4 ,they found in their experiments1 that while the legumes have the power of obtaining their nitrogen from the air1 cereals have not4 ,similar experiments by ,atwater in ,america1 and others1 support this conclusion4 ,their conclusions may be briefly epitomised as follows3-- 7a7 ,that the leguminous plants--such as peas1 c4--have the power of drawing their nitrogen supplies from the free nitrogen of the air in a way not possessed by other plants2 and that they thus possess two sources of nitrogen--the soil and the air4 7b7 ,that this absorption of free nitrogen is not effected directly by the plant1 but is the result1 so to speak1 of the joint action of certain micro-organisms present in certain soils and in the plant itself1 7symbiosis74 7c7 ,that this fixation is connected with the formation of minute tubercles on the roots of the plants of the leguminous class2 and that these tubercles may be the home of the fixing organism4 7d7 ,that these fixing micro-organisms are not present in all soils4#bg ,while the relation of free nitrogen to the plant has long been1 and still is1 a very obscure problem1 it was early recognised that the combined nitrogen present in soils and manures was an important source of plant-food4 ,reference has already been made to the early theory of ,sir ,kenelm ,digby regarding the value of nitrates4#bh ,de ,saussure1 as we have also already seen1 was fully impressed with the importance of applying nitrogen to the soil as a manure4 ,liebig's early attitude on this question was to the effect1 that to apply nitrogen in manures was quite unnecessary1 as the plant had a sufficient source in the ammonia present in the air1 which he erroneously supposed was sufficient in quantity to supply all the needs of the crops4 ,despite this early recognition of the value of combined nitrogen to the plant1 it is only of recent years that we have obtained any definite knowledge as to the respective value of its different compounds as manures1 or as to the form in which it is assimilated by the plant4 ,it exists in three forms--7#a7 as organic nitrogen2 7#b7 as ammonia salts2 7#c7 as nitrates and nitrites4 ,much experimental work has during late years been devoted to studying the comparative action and merits of these three forms4 ,relation of ,organic ,nitrogen to the ,plant4 ,first1 as to the relation of organic nitrogen to the plant4 ,there is a large number of different organic compounds which contain nitrogen4 ,that the plant is able to assimilate certain of these organic compounds1 seems1 from several experiments1 to be extremely probable4 ,from certain researches1 carried out as far back as the year #aheg1 ,sir ,charles ,cameron concluded that the plant could assimilate one of them--viz41 urea4 ,from what1 however1 we have subsequently learned regarding the process of nitrification1 it is quite probable that the nitrogen in these experiments was first converted into nitrates before being assimilated4 ,at any rate1 as the plants were not tested for urea1 the experiments must be regarded as leaving the problem unsolved4 ,other experiments were carried out of a similar nature by ,professor ,s4 ,w4 ,johnson1 the different kinds of nitrogen experimented with being uric acid1 hippuric acid1 and guanine4 ,but here1 again1 no definite conclusion can be drawn1 as no analyses were made of the plants4 ,more recently1 however1 ,dr ,hampe has carried out experiments with urea1 uric acid1 hippuric acid1 and glycocoll4 ,these experiments may be held as demonstrating the fact that at least one organic compound of nitrogen is capable of being assimilated1 as urea was actually identified as being present in the plants experimented with4 ,from further experiments1 carried out by ,dr ,paul ,wagner and ,wolff1 glycin1 tyrosin1 and kreatin are able to be assimilated by the plant4 ,plants able to absorb certain ,forms of ,organic ,nitrogen4 ,we may conclude1 then1 from these interesting experiments1 that plants are able to absorb certain organic forms of nitrogen4 ,that they do so in nature to any extent is extremely improbable1 such organic forms of nitrogen being rarely present in the soil1 or if present1 being converted into ammonia or nitrate salts before assimilation4 ,nature of ,humus in the ,soil4 ,while on the subject of organic nitrogen1 reference may be briefly made to that substance known as humus1--the name applied to the organic portion of soils1--a substance which figures so largely in early theories of plant-nutrition4 ,the most elaborate investigation of the composition of humus has been carried out by ,mulder4 ,according to ,mulder1 it is composed of a number of organic bodies1 and he has identified the following substances--ulmin1 humin1 ulmic1 humic1 geic acids1 c4 ,these bodies are composed of carbon1 hydrogen1 and oxygen1 which are invariably associated with nitrogen4 ,detmer and ,simon have further investigated the subject4 ,the true function of humus1 it would seem1 in addition to its numerous mechanical properties1 is to furnish1 by its decomposition1 carbonic acid and nitrogen--in the form of ammonia and nitric acid--to the soil2 the former acting as a solvent of the mineral food1 the latter as the source of the plant's nitrogen4 ,the old theory1 therefore1 that the presence of humus in a soil is a condition of fertility1 is not so far removed from the truth4 ,where there is an abundance of humus in the soil there is likely also to be an abundance of nitrogen4 ,relation of ,ammonia to the ,plant4 ,it seems to be beyond doubt that nitrogen is directly absorbed by plants in the form of ammonia4 ,liebig1 as we have seen1 concluded that this was the great source of nitrogen for the plant1 and that the ammonia compounds present in the air were an all-sufficient supply4 ,subsequent research1 while confirming his belief so far as regards the capability of plants to assimilate nitrogen in the form of ammonia1 has proved that the amount of ammonia present in the air is very minute1 and utterly inadequate to supply the plant with the whole of its nitrogen4 ,investigations have been made on this subject by ,graeger1 ,fresenius1 ,pierre1 ,bineau1 and ,ville4 ,according to ,ville's researches1 which are among the most recent1 the amount does not exceed #cj parts per thousand million parts of air4#bi ,some conception of the value of this source of nitrogen may be gained by estimating the quantity falling1 dissolved in rain1 on an acre of soil throughout the year4 ,various estimations of the total amount of combined nitrogen1 which is in this way brought to the soil1 have been made4 ,a certain amount of discrepancy1 it is true1 is to be found in these various estimations1 no doubt largely due to the difference in the circumstances under which the investigations were carried out4 ,mr ,warington has made several investigations at ,rothamsted1 and1 according to his most recently published figures1 the total quantity only amounts to #c4cg lb4 per acre per annum--of which only #b4ec lb4 is as ammonia itself4#cj ,as already mentioned1 there can be little doubt that plants can absorb nitrogen in the form of ammonia4 ,the question of how far plant-leaves are able to absorb ammonia is a much debated one4 ,it is probable that if they can do so1 it is only to a very small extent4#ca ,the question as to whether the plant's roots can absorb ammonia or not1 is also a very keenly debated one4 ,the point is a very difficult one to decide1 and is much complicated by the consideration that ammonia1 when applied to the the soil1 is so speedily converted into nitric acid4 ,despite1 however1 these difficulties1 and the vast amount of controversy on the point1 the experiments of ,ville1 ,hosaeus and ,lehmann1 seem to indicate beyond doubt that ammonia is a direct source of nitrogen4 ,lehmann's experiments would seem1 further1 to indicate that there are certain periods of a plant's growth when its preference for ammonia salts seems to be greater than at other times4 ,the point1 however1 it must be confessed1 is still an obscure one4 ,the great difficulty in deciding it1 as has just been said1 lies in the fact that ammonia salts1 when applied to a soil1 are1 by the process of nitrification1 converted into nitrates4 ,in experimenting1 therefore1 with ammonia1 and noting the results1 it is wellnigh impossible to say1 except by subsequent analyses1 whether the nitrogen in the ammonia salts has not been converted into nitrates before assimilation4 ,relation of ,nitric ,acid to the ,plant4 ,thirdly1 as to nitrogen in the form of nitrates4 ,while it is true that plants can absorb nitrogen in certain organic forms and as ammonia salts1 it is now a well-known fact that the chief1 and by far the most important1 source of nitrogen is nitric acid4 ,probably more than #ij per cent of the nitrogen absorbed by green-leaved plants from the soil is absorbed as nitrates4 ,the tendency of all nitrogen compounds in the soil is towards conversion into nitric acid4 ,it is the final form of nitrogen in the soil4 ,the precise method in which this conversion takes place is a discovery of only a few years' standing4 ,the great economic importance of this discovery1 made by the ,french chemists ,schloesing and ,muentz1 and associated in this country with the names of ,warington1 ,munro1 and ,p4 ,f4 ,frankland1 is only gradually being appreciated4 ,it is without doubt one of the most interesting made in the domain of agricultural chemistry of late years4 ,nitrification4 ,it was in the year #ahgg that the two ,french chemists above referred to published the results of some experiments they had carried out1 which proved that nitrification--the name given to the process by which ammonia or other nitrogen salts are converted in the soil into nitric acid--was due to the action of micro-organic life4 ,the basis of the theory rests upon the fact that dilute solutions of ammonia salts or urine1 containing all the necessary constituents of plant-food1 if previously sterilised1 may be kept for an indefinitely long period of time1 provided the air supplied be filtered through cotton wool1--so as to prevent the entrance of micro-organisms--without any formation of nitrates4 ,introduce1 however1 into such a solution a little fresh soil1 and nitrification will soon follow4 ,the conditions under which the nitrification ferment acts1 as well as the nature of the ferment1 or rather ferments1 have subsequently been carefully studied by ,schloesing and ,muentz1 ,winogradsy1 ,deherain1 ,kellner1 and other ,continental observers1 and especially by ,warington1 ,munro1 and ,p4 ,f4 ,frankland in this country4 ,these conditions cannot be gone into here4 ,they will be fully discussed in the chapter on ,nitrification4 ,briefly stated1 they are a certain range of temperature 7between slightly above freezing-point and #ej deg4 ,c41 the maximum activity taking place1 according to ,schloesing and ,muentz1 at about #cj deg4 ,c472 a plentiful supply of atmosphere oxygen 7hence the fact observed by ,warington1 that nitrification is chiefly limited to the surface-soil72 a certain amount of moisture2 and the presence of certain of the necessary mineral plant constituents1 and the presence of carbonate of lime4 ,the light which these discoveries throw upon the extremely complicated question of the fertility of the soil is considerable1 as it follows that no soil can be regarded as really a fertile one in which the process of nitrification does not freely take place4 ,they furthermore explain many facts1 hitherto observed but not well understood1 with regard to the action of different nitrogenous manures4 ,ash ,constituents of the ,plant4 ,we now come to consider the present state of our knowledge on the essentialness of the ash or mineral portion of the plant4 ,while a portion of the plant's substance which1 up to ,liebig's time1 had obtained little notice1 it has1 since the publication of his famous mineral theory1 obtained an ever-increasing amount of investigation4 ,up till #ahjj practically nothing was known of the function of the ash constituents4 ,in #ahjb de ,saussure wrote that it was unknown whether the constituents of many plants were due to the soils on which they grew1 or whether they were the products of vegetable growth4 ,some two years later1 however1 he was enabled to carry out a number of experiments which really placed the subject on a firm scientific basis4 ,the essentialness of the ash constituents was only1 however1 placed beyond all doubt by ,wiegmann and ,polstorff's researches1 carried out in #ahdj4 ,reference has already been made to the great stimulus given to research by the promulgation of ,liebig's mineral theory4 ,methods of ,research4 ,in epitomising the vast amount of work carried on since #ahdj1 with the view of ascertaining the essentialness of the various substances found in the ash of plants1 two methods of experimentation have been followed4 ,artificial ,soils4 ,the first of these two methods was that adopted in the famous experiments1 carried out by ,prince ,salm-,horstmar1 which have done so much to further our knowledge on this question4 ,it consisted in growing plants on an artificial soil--formed out of sugar-charcoal1 pulverised quartz or purified sand--to which were added the different food constituents4 ,water-culture4 ,while the results obtained by ,prince ,salm-,horstmar by this method were of a most valuable nature1 subsequent experimenters have abandoned his method for the other method--viz41 water-culture4 ,the medium used in this process is pure water2 and it is from experiments carried out in water-culture that much of our present knowledge1 in regard to the relation of the ash constituents to the plant1 is due4 ,the names of those who have worked in this department are very numerous4 ,among them may be mentioned ,knop1 ,sachs1 ,stohmann1 ,nobbe1 ,rautenberg1 ,kuehn1 ,lucanus1 ,w4 ,wolff1 ,hampe1 ,beyer1 ,e4 ,wolff1 ,p4 ,wagner1 ,bretschneider and ,lehmann4 ,the results obtained by these and other experimenters have demonstrated the following facts4 ,the substances which have been found in the ash of plants are3 potash1 soda1 lime1 magnesia1 oxide of iron1 oxide of manganese1 phosphoric acid1 sulphuric acid1 silica1 carbonic acid1 chlorine1 lithia1 rubidia1 alumina1 oxide of copper1 bromine1 iodine1 and occasionally even other substances4 ,of these1 however1 only six are probably absolutely necessary for plant-growth--viz41 potash1 lime1 magnesia1 oxide of iron1 phosphoric acid1 and sulphuric acid4 ,three other substances seem also to be almost invariably present1 and may possibly be essential--in very minute quantities at any rate--viz41 chlorine1 soda1 and silica4 ,with regard to alumina and oxide of copper1 these constituents must be regarded as accidental2 while iodine and bromine only occur in the ash of marine plants4 ,method of ,absorption of ,plant-food4 ,a department of vegetable physiology which has had much work devoted to it is the method in which plant-roots absorb their food4 ,the plant's nourishment is absorbed in solution by means of the roots4 ,its absorption takes place1 according to ,fischer and ,dutrochet1 who have investigated the subject at great length1 by the process known as endosmosis4 ,it has also been established by numerous experiments1 that different plants require different constituents in different proportions4 ,water as a ,carrier of ,plant-food4 ,the function performed by water1 as the carrier of plant-food1 and the motion of the sap of the plant1 are questions which have also received much attention4 ,the motion of the plant's sap seems to have attracted a great deal of attention at a very early stage of the study of plant physiology4 ,as far back as #afgi1 ,marriotte studied it4 ,among other old experimenters were ,hales1 ,guettard1 ,senebier1 ,saint-,martin1 de ,candolle1 and ,miguel4 ,in more recent times1 it has been investigated by ,schuebler1 ,lawes and ,gilbert1 ,knop1 ,sachs1 ,unger1 and ,hosaeus4 ,some idea of the enormous amount of water transpired by plant-leaves may be gained by the statement that from #bcc lb4 to #iab lb4 of water are transpired for every pound of plant-tissue formed4#cb ,agronomy4 ,when we come to deal with questions relating to the chemistry of the soil1 we find that so much investigation has been devoted to this one branch of agricultural chemistry as to constitute it a special branch by itself--known in ,france under the name of agronomie--and being taught in the large agricultural colleges by special professors of the subject4 ,the value of studying the properties of soils was recognised at an early period4 ,this study was for long largely confined to their physical1 or1 what are popularly known as their mechanical properties4 ,thus ,sir ,humphry ,davy ascertained many important facts with regard to the heat and water absorbing and retaining properties of soils4 ,retention by ,soil of ,plant-food4 ,it was not till a later period that the power soils possess of fixing from their watery solutions various plant-foods1 both organic and inorganic1 was discovered4 ,the earliest recognition of this most important property of soils was made by ,gazzeri1 who1 in #ahai1 called attention to the fact that the dark fluid portion of farmyard manure was purified on passing through clay4 ,he concluded that soils1 more especially clayey soils1 possessed the property of being able to fix from their watery solutions the necessary plant-food constituents1 and fix them beyond risk of loss1 only affording a gradual supply to the plant as required4 ,the first experiments carried out on this subject were those by ,huxtable and ,thompson in #ahej4 ,the liquid portion of farmyard manure was filtered through soil and subsequently examined1 when it was found to have not only lost its colour1 but also to have lost its smell4 ,ammonia and ammonia salts were also experimented with1 and it was found that soils possessed the power of fixing ammonia4 ,to ,thomas ,way1 however1 we are indebted for the most valuable contribution on this important subject made by any one single investigator4 ,his experiments were not merely carried out with regard to ammonia1 but also with regard to other bases--such as potash1 lime1 magnesia1 soda1 c4 ,since ,way's experiments much work has been done by ,liebig1 ,stohmann1 ,henneberg1 and ,heiden1 as also by ,voelcker1 ,eichhorn1 ,knop1 ,rautenberg1 ,pochwissnew1 ,warington1 ,beyer1 ,bretschneider1 ,sestini1 ,laskowsky1 ,strehl1 ,pillnitz1 ,peters1 ,w4 ,wolff1 ,lehmann1 and ,biedermann4 ,bases and ,acids fixed by ,soil4 ,from these experiments it may be taken as proved beyond doubt that soils have the power of fixing1 to a greater or less extent1 the following bases3 ammonia1 potash1 lime1 magnesia and soda2 as well as the two acids1 phosphoric and silicic4 ,the order in which the different bases are fixed is an important point4 ,it would seem that the soil has a greater affinity for the more valuable manurial substances1 such as ammonia1 potash1 and lime1 and that these substances are first fixed4 ,that in fixing any one of the above-mentioned bases from its solution1 it can only do so at the expense of another base4 ,thus1 in fixing potash1 either lime1 magnesia1 or soda must be given up4 ,further1 when a base in solution1 as sulphate or chloride1 is absorbed by a soil1 the base is alone fixed1 while the sulphuric acid or chlorine is left in solution4 ,lastly1 the amount of base absorbed by a soil depends on the concentration of its solution1 on the nature of its combination1 and the temperature4 ,way found in his experiments that a clay soil has more power than a peaty soil1 and that a peaty soil has more power than a sandy soil4 ,causes of this ,fixation4 ,so much for the fact of soil absorption2 as to the cause or causes of this absorption1 a great number of theories have been put forward4 ,those may be divided into two classes--those accounting for it as due to physical properties of the soil2 and those1 on the other hand1 explaining it as due to chemical action4 ,to the latter class ,way's belonged4 ,he explained it as due to the formation in the soil of hydrated double silicates1 consisting of a silicate of alumina1 along with a silicate of the base fixed4 ,bruestlein and ,peters1 on the other hand1 were of the opinion that it was purely physical in its nature4 ,a theory has been advanced that it is due to the formation of insoluble ulmates and humates1 formed by the union of ulmic and humic acids1 along with the bases fixed4 ,among others who devoted investigation to this interesting question1 may be mentioned ,rautenberg and ,heiden4 ,on reviewing the evidence1 it seems to be pretty well established that it really is mainly a chemical act1 due chiefly to the formation of double silicates1 and doubtless to a certain extent to the formation of insoluble humates and ulmates4 ,heiden's experiments would seem to indicate1 however1 that it is also partly of a physical nature4 ,with regard to the absorption of phosphoric acid1 this has been shown to be a chemical act1 and depends on the formation of insoluble phosphates of calcium1 iron1 aluminium1 and magnesium1 the percentage of iron especially determining this4 ,much analytical work has been accomplished of late years with a view of ascertaining the amount of ash in different kinds of plants1 and in the different parts of the plant4 ,action of ,manures4 ,the department of agricultural chemistry which has been most largely developed of late years is that connected with the problems of manuring4 ,it is1 from a practical point of view1 of most value4 ,it is some considerable time since we have recognised that the only three ingredients it is1 as a rule1 expedient to apply as artificial manures1 are nitrogen1 phosphoric acid1 and potash4 ,the nature1 mode of action of the different compounds1 and properties of these three substances1 and their comparative influence in fostering plant-growth1 together with the economic question of which form is1 under various circumstances1 the most economical for the farmer to use1 have together given rise to a large number of field and pot experiments4 ,as the principles underlying this practice form the subject of the following treatise1 any further discussion of the question must be left to the following chapters4 ,note4--,the reader interested in the historical development of agricultural chemistry is referred to ,sir ,j4 ,h4 ,gilbert's ,presidential ,address to the ,chemical ,section of the ,british ,association1 #ahhj4 ,,footnotes3 #a ,the ,history of the ,chemical ,elements4 ,by ,sir ,henry ,e4 ,roscoe1 ,f4,r4,s4 7,wm4 ,collins1 ,sons1 ,co47 #b ,van ,helmont's science was1 however1 of an extremely rudimentary nature1 as may be evidenced by the belief he entertained that the smells which arise from the bottom of morasses produce frogs1 slugs1 leeches1 and other things2 as well as by the following recipe which he gave for the production of a pot of mice3 ,press a dirty shirt into the orifice of a vessel containing a little corn1 after about twenty-one days the ferment proceeding from the dirty shirt1 modified by the odour of the corn1 effects a transmutation of the wheat into mice4 ,the crowning point in this recipe1 however1 lay in the fact that he asserted that he had himself witnessed the fact1 and1 as an interesting and corroborative detail1 he added that the mice were born full-grown4 ,see ',louis ,pasteur3 ,his ,life and ,labours4' ,by his ,son-in-law4 ,translated by ,lady ,claud ,hamilton4 7,longmans1 ,green1 ,co47 ,p4 #hi4 #c ,he then goes on to relate a number of experiments by ,cornelius ,drebel and ,albertus ,magnus1 showing the refreshing power of this balsam1 and then those of ,quercitan with roses and other flowers1 and his own with nettles4 #d ,priestley1 however1 did not realise that carbonic acid gas was a necessary plant-food2 on the contrary1 he considered it to have a deleterious action on plant-growth4 ,percival was really the first to point out that carbonic acid gas was a plant-food4 #e ,it is recorded as an instance of the scientific enthusiasm of the man1 that he was wont to carry about with him bottles containing oxygen1 which he had obtained from cabbage-leaves1 as also coils of iron wire1 with which he could illustrate the brilliant combustion which ensued on burning the latter in oxygen gas4 #f ,for a full account of ,senebier's researches1 see ',physiologie vegetale1 contenant une description des organes des plantes1 et une exposition des phenomenes produits par leur organisation1 par ,jean ,senebier4' 7#e tomes4 ,geneve1 #ahjj47 #g ,how ,crops ,grow4 ,by ,professor ,s4 ,w4 ,johnson4 ,macmillan ,co4 7,introduction1 p4 #d47 #h ,see p4 #dj to #de4 #i ,elements of ,agricultural ,chemistry1 in a course of ,lectures for the ,board of ,agriculture4 ,by ,sir ,humphry ,davy4 7,london1 #ahca47 #aj ,this department of agricultural research was subsequently carried on by ,sprengel1 ,schuebler1 and others4 #aa ,born in ,paris1 #ahjb2 died #aath ,may #ahhg4 #ab ,see p4 #dj4 #ac ,while much of ,boussingault's work was carried out previous to the year #ahdj1 he continued to enrich agricultural chemistry with numerous valuable contributions up till the time of his death4 ,it may be well here to mention the names of his most important contributions to agricultural science1 made subsequent to #ahdj4 ,in #ahdc he published1 in a work entitled ',economie ,rurale1' the results of his numerous experiments and researches4 ,this work is well known to ,english agriculturists from an ,english translation which appeared in #ahde 7,boussingault's ',rural ,economy1' translated by ,g4 ,law4 ,h4 ,balliere1 ,london74 ,in #ahfj appeared the first volume of his last great work1 ',agronomie ,chimie ,agricole et ,physiologie' ,this work1 which consisted of seven volumes1 was not finished till #ahhd4 ,he died on the #aath of ,may #ahhg4 ,it may be added that the ,royal ,society of ,london awarded him the ,copley medal in #ahhg4 #ad ,see ,british ,association ,proceedings1 #ahhj1 p4 #eaa4 #ae ,it may be pointed out that1 while the amount of ammonia washed down by the rain is small1 ,schloesing has found in some recent experiments that a damp soil may absorb from the air in the course of a year #ch lb4 of combined nitrogen1 chiefly ammonia1 per acre4 ,see p4 #acb4 #af ,the example1 set by ,germany1 has been followed by other countries in which well-equipped research stations now exist4 ,perhaps the most striking example of the rapid development of the means of agricultural research is furnished by the ,united ,states of ,america4 ,at present over fifty agricultural experiment stations1 more or less well equipped1 exist at present in that country1 all liberally supplied by ,state aid4 ,the earliest to be founded1 it may be added1 was that at ,middletown1 ,connecticut1 the date of its institution being #ahge4 #ag ,it may thus claim to be the second oldest experimental station1 that instituted by ,boussingault at ,bechelbronn in ,alsace being the oldest4 #ah ,for an account of the ,rothamsted experiments1 and a short biography of ,sir ,john ,lawes1 the reader is referred to a pamphlet by the present writer1 entitled ',sir ,j4 ,b4 ,lawes1 ,bart41 ,,ll4,d41 ,f4,r4,s41 and the ,rothamsted ,experiments' 7',scottish ,farmer' ,office1 #ic ,hope ,street1 ,glasgow74 #ai ,of these numerous elaborate experiments1 perhaps those which have attracted the most widespread interest amongst agriculturists have been those carried out on the growth of wheat on the same land year after year for a period of nearly fifty years4 ,the important light which this series of experiments has thrown upon the theory of the rotation of crops1 and the subject of the manuring of cereals1 is very great4 #bj ,associated in some cases with phosphorus and sulphur4 #ba ,it must be pointed out that plant-respiration does not take place only during the night-time4 ,it probably goes on at all times1 but it is only during the night-time that its action is apparent1 as the reverse process of carbon assimilation1 which goes on at an incomparably greater rate1 masks its action during the daytime4 #bb ,the length of the day has an important influence on plant-growth1 as is evidenced by the rapid growth of vegetation in ,norway and ,sweden4 ,in these countries there is a late spring1 and a short and by no means hot summer1 but a very long period of daylight4 #bc ,a point of great interest which these experiments elucidated is that nocturnal repose is not absolutely necessary for the growth and development of all plants4 #bd ,see pp4 #ae and #bb4 #be ,see p4 #bb4 #bf ,see ,chapter ,,iii41 pp4 #abj and #aca4 #bg ,further reference is made to this subject in ,chapter ,,iii41 p4 #acf4 #bh ,see p4 #f4 #bi ,see ,phil4 ,trans41 ,part ,,ii41 #ahfa1 pp4 #ddd-ddf4 ,lawes ,gilbert4 ,schloesing has found in the air in the neighbourhood of ,paris #a lb4 of ammonia in #bf1jjj1jjj cubic yards2 while ,muentz found only about half that amount in a similar quantity of air on the top of the ,pic du ,midi4 #cj ,see ,chapter ,,iii41 pp4 #aai1 #abj2 ,appendix1 p4 #aee4 #ca ,some recent experiments by ,dyer and ,smetham would seem to show that comparatively small quantities of ammonia in the air prove actually hurtful to plant-life4 ,thus they found that one volume of ammonia in #ajjj volumes of air was fatal to hardy plants2 while one volume in #cjjj volumes killed tender ones4 #cb ,according to the experiments of ,hellriegel and ,wollny4 ,the quantity1 it may be added1 varies with the leaf-surface and the length of the period of growth of the plant4 ,it is greatest with clovers and grasses1 and least in the potatoes and roots4 ,,part ,,ii4 ,,principles ,,of ,,manuring ,,chapter ,i4 ,,fertility ,,of ,,the ,,soil4 ,it is necessary to clearly understand to what the fertility of a soil is due ere we can hope to master the theory of manuring4 ,what constitutes ,fertility in a ,soil4 ,the question1 ,what constitutes fertility in a soil8 is by no means an easy one to answer4 ,if we say1 ,the presence of a plentiful supply of the constituents which form the plant's food1 our answer will be incomplete4 ,similarly1 if we reply1 ,a certain physical condition of the soil--here1 again1 it will be found equally unsatisfactory2 for fertility of a soil depends both on its physical condition and on its chemical composition1 and indeed even on other circumstances4 ,it may be well1 then1 before proceeding to treat of the nature and action of the different manures1 to offer a brief statement of the conditions of fertility so far1 at any rate1 as we at present know them4 ,for it may be well to warn the reader that1 despite the great amount of work carried out on this subject by experimenters1 we still have much to learn before we shall be in a position fully and clearly to understand the subject of soil-fertility in all its bearings4 ,apart altogether from the influence exerted by climate1 latitude1 altitude1 and exposure1 the fertility of a soil may be said to depend on the following properties4 ,these we may divide into three groups or classes3-- #a4 ,physical or mechanical4 #b4 ,chemical4 #c4 ,biological4 ,i4 ,physical ,properties of a ,soil4--,the physical properties of a soil are generally admitted to have a very important bearing on its fertility4 ,this has been long practically recognised1 and perhaps has in the past been unduly exalted in importance1 at the expense of the no less important functions of the chemical4#cc ,the reason of this is doubtless to be ascribed to the fact that it is much easier to study the physical properties of a soil than it is to study the chemical2 and that1 while we are in possession of a very large amount of useful information with regard to the former1 we are at present only on the threshold of our knowledge of the latter4 ,variety of ,soils4 ,it is a matter of common observation that soils differ widely in their mechanical nature4 ,the early recognition of this fact is evidenced by the large number of technical terms which have been long in vogue among farmers descriptive of these differences4 ,thus soils are in the habit of being described as heavy1 light1 stiff1 strong1 warm1 cold1 wet1 damp1 peaty1 clayey1 sandy1 loamy1 c41 c4 ,absorptive ,power for ,water4 ,one of the most important of the physical properties of a soil is its power to absorb water4 ,water to the plant economy is just as important and necessary as it is to the animal economy4 ,consequently it is of primary importance to examine into the conditions which regulate the absorption of this important plant-food by the soil4 ,by the absorptive power of a soil is meant its capacity for drinking in any water with which its particles may come in contact4 ,this power depends1 first1 on the predominance of its proximate constituents--viz41 sand1 clay1 carbonate of lime1 and humus2 and secondly on the fineness of the soil-particles4 ,absorptive ,power of ,sand1 ,clay1 ,humus4 ,first1 then1 with regard to the absorptive power of sand1 clay1 and humus4 ,of these1 sand possesses this power to the least extent1 clay to a greater extent1 while humus possesses it most of all4#cd ,the extent1 therefore1 of the absorptive power of a soil depends very much on the proportions in which it possesses these three ingredients4 ,the more sandy a soil is1 the less will its power be of absorbing water2 and this1 there is little doubt1 is one of the reasons why a sandy soil is1 as a rule1 an unfertile soil4 ,of course there are other and even more important reasons2 but that this absorptive power has an important bearing on the question is conclusively proved by the fact that sandy soils are more fertile in a climate where rain is frequent than in one where much dry weather prevails4 ,the incapacity of a sandy soil to absorb a large quantity of moisture is not fraught with such evil effects to the crops in the former case1 because it is counteracted by the climatic conditions1 which obviate the necessity1 in a soil1 of possessing great absorptive powers4 ,the converse1 of course1 we may mention in passing1 holds good of clayey soils4 ,fineness of ,soil-particles4 ,the second quality in a soil on which its absorptive power depends is the fineness of its particles4 ,the great benefit which a soil derives from a good tilth1 in this respect1 was one of the reasons why ,tull's system of horse-hoeing husbandry was so successful in its results4#ce ,the finer the soil-particles1 it may be said generally1 the greater is the absorptive power of the soil4 ,limit to ,fineness4 ,there is1 however1 a limit to the fineness to which the particles of a soil ought to be reduced2 for it has been found by experiment that when a certain degree of fineness is reached1 the absorptive power decreases with any further pulverisation4 ,a ,german experimenter found1 for example1 that a garden loam1 capable of absorbing #aad per cent of water in its natural state1 when pulverised very fine was able to absorb only #fb per cent of water4 ,here1 clearly1 the limit to which it is advisable to pulverise a soil had been exceeded4 ,reason of the above4 ,it is not difficult to see why this should be so4 ,the amount of water that a soil can soak up is due to the number of pores1 or air-spaces1 it contains of a certain size4 ,if these pores are large and few in number1 the amount of water absorbed will be naturally less than when they are numerous and smaller in size4 ,up to a certain extent1 the more a soil is broken the greater will be the number of pores created1 of a size to permit the water to soak in4 ,beyond that point the pores become too minute1 and the soil becomes too compact1 each particle clinging together too closely4 ,retentive ,power of ,soils for ,water4 ,now closely connected with this absorptive power of soils1 which we have just been considering1 is the power soils possess of holding or retaining the water they absorb4 ,this power1 it will be seen at a glance1 must have an important bearing on the fertility of a soil4 ,importance of ,retentive ,power4 ,as a considerable interval often elapses between the periods of rainfall1 soils1 if they are to support vegetable growth1 must be able to store up their water-supply against periods of drought4 ,this is all the more necessary when we remember that1 in the case of heavy crops1 the rainfall would often be inadequate to supply the water necessary for their growth4 ,in fact1 it has been estimated that the average evaporation from soils bare of any cultivation is equal to the rainfall4 ,that the evaporation from soils covered with vegetation is very much greater1 has been strikingly shown by a calculation made by the late eminent ,american botanist1 ,professor ,asa ,gray1 who calculated that a certain elm-tree offered a leaf-surface1 from which active transpiration constantly went on1 of some five acres in extent2 while it has further been calculated that a certain oak-tree1 within a period of six months1 transpired during the daytime eight and a half times more water than fell as rain on an area equal in circumference to the tree-top4#cf ,just as the state of the fineness of the soil-particles has an important influence on the absorptive power of soils1 so1 too1 it is found1 it has an important bearing on the rate at which evaporation takes place4 ,evaporation goes on to the greatest extent in soils whose particles are compacted together1 capillary action in this case taking place more freely1 and effecting evaporation from a greater depth of soil4 ,the stirring of the surface portion of the soil1 as for example by hoeing or harrowing1 has for this reason an important influence in lessening the amount of evaporation1 and minimising the risks of drought1 by breaking the capillary attraction4 ,the amount of evaporation which takes place from a soil covered with a crop1 depends largely on the nature of the crop2 a deep-rooted crop1 since it draws its moisture from a wider area of soil1 being more effective in drying a soil than a shallow-rooted crop4 ,the difference in the amounts evaporated from a cropped and a bare fallow soil has been shown at ,rothamsted to equal a rainfall of nine inches1 the crop being barley4 ,the increase1 of course1 is due to the water which the crop transpires4#cg ,it may be generally said that the greater the absorptive power of a soil1 the greater is its retentive power2 for soils that most largely absorb water are the most reluctant to part with it4 ,while these properties are undoubtedly necessary for fertile soils1 it is needless to add that they may be possessed by a soil to too great an extent4 ,the soil that is unable to throw off any excess of water becomes cold and damp1 and does not admit of proper tillage4 ,its pores become entirely choked up1 and the circulation of air1 which1 as we shall see1 is of so much importance1 is rendered impossible4 ,plants in such a soil are apt to sicken and die1 the water becomes stagnant1 and certain chemical actions are caused which give rise to poisonous gases1 such as sulphuretted hydrogen1 c4 ,a stiff clayey soil offers a good example of the disadvantage of over-retentiveness4 ,owing to the difficulty such soils experience in throwing off their excessive water1 they are extremely difficult to till2 and sowing operations are on that account apt to be delayed4 ,power ,plants have of absorbing ,water from a ,soil4 ,it is a strange fact1 and one worth noticing in this connection1 that the power plant-roots have of drawing their moisture from a soil1 seems to depend on the retentive power of the soil4 ,by this is meant that plants have not the means of exhausting the water in a retentive soil to such an extent as in a non-retentive soil4 ,in some extremely interesting experiments1 carried out by the well-known ,german botanist ,sachs1 it was found that plants wilted in a loamy soil1 whose water-holding capacity was #eb per cent1 when its moisture reached #h per cent2 while in a sandy soil--water-holding capacity #ba per cent--the same species of plant did not wilt until its moisture reached #a-a_/b per cent4 ,here1 then1 we see that on one kind of soil the plant was able to live1 and obtain sufficient water for its needs1 while it died of thirst in another soil1 although that soil contained quite as much moisture4 ,speaking generally1 we may say that ,hellriegel's experiments have shown that any soil can supply plants with all the water they need so long as its moisture is not reduced below one-third of the whole amount it can hold4#ch ,how to increase ,absorptive ,power of ,soils4 ,the absence or presence1 in excess1 of the above properties1 suggests a word or two on how these natural defects may1 to a certain extent1 be remedied artificially4 ,it stands to reason1 that if organic matter in a soil renders its absorptive power greater1 a simple method of improving a soil defective in this property is by the addition of organic matter4 ,one of the benefits of ploughing-in green crops on sandy soils is undoubtedly due to this fact2 the addition of farmyard manure having also a similar effect4 ,the absence of a sufficient amount of retentiveness1 such as is found in sandy soils1 in the same way suggests1 as a remedy1 the addition of clay2 and1 vice versa1 where the soil is too clayey1 the natural method of improvement will be the addition of sand4#ci ,shrinkage of ,soils4 ,in drying1 soils shrink4 ,those which shrink least are sandy and chalky soils4 ,humus soils1 on the other hand1 shrink most4 ,most favourable ,amount of ,water in a ,soil4 ,the amount of water in a soil most favourable for plant-growth is a question of considerable difficulty4 ,too great an amount of moisture renders the land cold2 air cannot obtain access to the soil-particles1 and the plants sicken and die4 ,hellriegel has found that as much as #hj per cent of what the soil can hold is hurtful to plants1 and that from #ej to #fj per cent is the best amount4#dj ,hygroscopic ,power4 ,a property possessed by soils in relation to water1 which is quite distinct from absorptive power1 is their hygroscopic power4 ,by this is meant their power of absorbing water from the air where it is present in the gaseous form4 ,this property is identical with the property which will be adverted to immediately--viz41 capacity for absorbing gases4 ,the extent to which soils possess this hygroscopic property seems to be regulated very much by the same conditions as regulate their ordinary absorptive power4#da ,this property is considered to be of great importance in the case of soils in hot climates1 where their agricultural value may be said to depend to a large extent upon it4 ,the amount of water1 however1 absorbed in this way is1 comparatively speaking1 insignificant4 ,lastly1 it may be observed that there are certain methods of drying soils afflicted with too much moisture4 ,these consist in making open ditches1 and thus relieving them of their superabundance of water1 or in planting certain kinds of trees1 such as willows and poplars4 ,the amount of green surface presented by the large number of leaves of trees1 from which the constant evaporation of water goes on1 is very great4 ,the consequence is that trees may be regarded as pumping-engines4 ,it is from this cause that foresters have noticed that clay lands are apt to become wetter after the trees growing upon them have been cut down4#db ,capacity for ,heat in ,soils4 ,a property which depends largely on those we have just been considering is the capacity soils possess of absorbing and retaining heat4#dc ,the temperature of a soil1 of course1 largely depends on the temperature of the air2 but this1 we must not forget1 depends also on the soil itself4 ,the heat given forth by the sun's rays strikes the soil1 with the result that1 while so much of its heat is absorbed1 a certain portion--and this will vary according to the nature of the soil--of its heat is radiated into the air4 ,the changes in the temperature of the soil naturally take place more slowly than the changes in the temperature of the air2 the depth of soil thus affected by those changes varies also in different climes4 ,it has been calculated that in temperate climes the changes of temperature occurring from day to night are not felt much below three feet down4 ,the ,explanation of ,dew4 ,we have1 it may be stated1 generally two processes going on4 ,during the day the soil is engaged in absorbing its heat from the sun's rays2 when night comes1 and the sun goes below the horizon1 the air is chilled below the temperature of the soil1 which radiates out its stored-up heat into the air4 ,the result is that the temperature of the soil is soon reduced below the temperature of the air1 and the moisture1 present in the air in the form of vapour1 coming in contact with the cold surface of the earth1 is condensed into dew1 which is deposited1 and is seen best early in the morning before the sun has had time to evaporate it again4 ,dew is most abundant in summer-time1 for the reason that the difference in temperature of the day and night is then greatest4 ,in winter-time it is seen as hoar-frost4 ,heat of ,soils4 ,the temperature of a soil1 however1 is due to other sources than the sun's rays4 ,whenever vegetable matter decays1 there is always a certain amount of heat generated4 ,soils1 therefore1 in which there is a large amount of decaying vegetable matter1 are certain to receive more heat from this source than soils of more purely mineral nature4 ,heat in ,farmyard ,manure4 ,a good example of the amount of heat that accompanies fermentation1 or decay of vegetable matter1 is seen in the case of rotting farmyard manure4 ,the danger of loss of the volatile ammonia from this cause is often great1 and care must be taken to prevent fermentation going on too quickly1 and the temperature from becoming too high4#dd ,the actual increase in the temperature of a soil effected by the addition of certain bulky organic manures1 such as farmyard manure1 may thus be considerable4 ,in some experiments carried out at ,tokio1 ,japan1 it was found that the application of #bj tons of farmyard manure per acre increased the temperature of the soil to a depth of five inches1 for a period of nearly a month1 on an average1 one and a half degrees ,fahrenheit4 ,the amount of water present in a soil1 it may be noticed in passing1 will have a considerable effect in regulating its temperature1 a damp soil being1 as a rule1 a cold soil4 ,the ,cause of the ,heat of ,fermentation4 ,it may be asked1 ,how is the decay1 or fermentation1 of vegetable matter1 such as farmyard manure1 caused8 or rather1 ,to what is it due8 ,decay of any substance is just its slow combustion or burning4 ,when a substance unites with the active chemical element in air--the oxygen gas--it is said to be oxidised4 ,now1 this union of a substance with oxygen is the explanation of burning1 and the phenomena of burning and decay are explained by the same chemical operation4 ,when bodies decay1 or when they burn1 they unite with oxygen3 when this union of a body and oxygen takes place very quickly1 and the result is a flame and very great heat1 then we call it burning2 when1 however1 it takes place slowly1 it is not called burning1 but simply oxidation or decay4 ,the ultimate products are the same1 however1 whether the body burns or decays2 and the process of decay is always accompanied by heat1 as well as the process of burning4#de ,it is not1 of course1 only the vegetable or organic matter in a soil that decays1 but also the mineral matter4 ,the oxidation1 however1 of the mineral matter in the soil takes place so slowly1 and the amount of heat generated by this oxidation is so slight1 that the temperature of the soil can scarcely be said to be much affected by it4 ,influence of ,colour of a ,soil4 ,there is still another quality of a soil on which its temperature depends1 and that is its colour4 ,this may seem at first sight to be scarcely worth taking into account1 and yet it has been shown to have a very striking influence on the temperature of a soil4 ,this naturally is best seen in climates where there is a good deal of sun4 ,dark-coloured soils have a greater heat-absorbing capacity than light-coloured soils2 and experiments carried out for the purpose of determining the extent of this influence have shown that under certain conditions the difference between a soil covered with a black substance1 and one covered with a white substance1 amounted to from #ac deg4 to #ad deg4 ,fahr4 ,other things being equal1 a crop on a dark-coloured soil will be sooner ripened than one on a light-coloured soil4 ,a soil covered by a crop is cooler than one without any crop4 ,the ,power ,soils have for absorbing ,gases4 ,we have just seen that one cause of the heat of soils is the oxidation which is constantly going on in all soils1 but more rapidly in soils containing a large quantity of vegetable matter4 ,this suggests a word or two on the power soils have of absorbing gases4 ,the chief gases in the atmosphere are oxygen and nitrogen4 ,both these gases are absorbed by soils1 although not in similar proportions4#df ,with regard to the former1 it is well known that a plentiful supply of oxygen in the pores of the soil is a necessary condition of fertility4 ,this was long ago experimentally proved by de ,saussure1 who showed that plants absorbed oxygen through their roots4 ,at certain periods of their growth this demand for oxygen on the part of the plant is greater than at other times4 ,for example1 seeds in the process of germination require to have free access to a plentiful supply of oxygen4 ,this fact emphasises the enormous importance of providing a good seed-bed1 and of seeing that the seed is not buried too deeply4 ,carbonic ,acid and ,ammonia4 ,in addition to oxygen and nitrogen1 the air contains other gases which are absorbed by the soil4 ,of these1 carbonic acid is the most abundant4 ,by far the largest portion of the carbonic acid which the soil obtains from the air1 is washed down in solution in the rain4#dg ,of the other constituents of the atmosphere1 the combined forms of nitrogen--viz41 ammonia1 nitric1 and nitrous acids--are the most important4 ,these are all absorbed by the soil1 but1 like carbonic acid1 they are chiefly washed down by the rain4 ,the amount of ammonia which may be absorbed by a soil from the air1 is very much greater than was formerly supposed4 ,some recent experiments by ,schloesing1 referred to in a following chapter1#dh show this4 ,a damp soil may in the course of a year absorb far more ammonia than that washed down in rain4 ,gas-absorbing ,power of ,soils varies4 ,the power of different soils to absorb these gases varies4 ,this variation depends not only on their physical properties1 but also on their chemical as well4 ,soils containing much organic matter have a greater capacity for absorbing gases than the more purely mineral ones4 ,absorption of ,nitrogen4 ,the absorption of nitrogen by the soil is a question of considerable importance4 ,it will be referred to later on under the heading of the biological properties of soils1 as it is fixed by the agency of micro-organisms4#di ,to recapitulate1 the chief physical or mechanical properties of a soil are its absorptive and retentive powers for water2 its capacity for heat2 and its power of absorbing gases4 ,it will be easily seen how tillage operations are calculated to influence these physical properties of a soil4 ,thus1 in the case of a stiff soil1 tillage increases its power for absorbing the atmospheric gases1 chiefly oxygen1 which are so necessary for rendering its fertilising matters available4 ,on the other hand1 in a light and too open soil it may exert quite a contrary effect4 ,it may be also well to refer here to the important influence these physical properties exercise on the growth of the plant4 ,plant-roots require a certain ,openness in the ,soil4 ,one of the functions of the soil is to support the plant in an upright position1 and this is a function which requires in the soil a certain amount of compactness or firmness4 ,on the other hand1 however1 a soil must not possess too great compactness1 otherwise the plant-roots will experience a difficulty in pushing their way downwards4 ,this is especially the case during the earlier periods of growth1 when the plant-roots are as yet extremely tender1 and experience great difficulty in overcoming much resistance4 ,the importance of preparing a mellow seed-bed will be thus at once seen to be based on sound scientific principles2 and this for a double reason4 ,not only does the young plant require every facility for developing its roots1 but also1 as has just been pointed out1 an abundant supply of oxygen is of paramount importance during the process of germination4 ,soil and ,plant-roots4 ,the whole question of the influence of the mechanical condition of the soil on the development of plant-roots is one of the highest importance and interest1 and is not so generally recognised as it ought to be4 ,natural tendency of ,plant-roots to grow downwards4 ,it may be taken as certain that the tangled condition of plant-roots is due to the resistance offered by the soil-particles1 and that the natural tendency of the plant-root is to grow downwards4 ,the roots1 in short1 would probably grow in as symmetrical a form as do the stalks or branches1 were it not that they are hindered from so doing by the soil-particles4 ,where1 then1 the soil is such as to offer much hindrance1 the growth of the plant cannot but be retarded4 ,some extremely interesting experiments have been performed by the eminent ,german chemist ,hellriegel on the influence which the closeness of the soil-particles has on root-development4 ,in these experiments peas and beans were grown in moistened sawdust1 more or less compactly compressed4 ,it was found that when the sawdust ,was compressed to any extent1 plant-growth took place very slowly1 or entirely ceased4 ,the importance of having plant-roots as widely developed in the soil as possible1 will be at once seen when we reflect that this means that the area of soil from which the plant derives its soil-food is thereby greatly increased4 ,another important consideration is1 that the deeper plant-roots can penetrate in a soil1 the more able--other conditions being equal--is the plant to withstand the action of drought1 as it can draw water for its needs from the deeper layers of the soil1 long after a plant1 whose roots do not penetrate so deeply1 has wilted4 ,plants require ,room4 ,another important bearing tillage has on plant-growth may here be discussed4 ,a problem of considerable difficulty is presented in the question1 ,how many individual plants will a certain piece of soil support in a healthy way8 ,for as plants require room1 it is imperative that they be not too closely crowded together4 ,the question resolves itself pretty much into one of quality against quantity4 ,experiments on this subject have shown that a certain area of soil is only able to support the healthy growth of a certain number of plants4 ,if the limit be exceeded1 the result is imperfect development4 ,number of ,plants on certain ,area increased by ,tillage4 ,it is obvious1 however1 that the more thoroughly tilled a soil is1 the greater will be the number of plants it will be possible to grow on it4 ,the roots1 instead of being forced to spread themselves along the surface-soil1 and thus take up a large amount of room1 will find no difficulty in striking downwards4 ,two or three plants may thus be enabled to grow in a thoroughly tilled soil in the same space as only one could before tillage4 ,american and ,english ,farming4 ,the above considerations throw considerable light on what seems to many farmers a strange anomaly--viz41 the fact that the return of farm produce per acre on ,american farms is1 as a rule1 very much less than that from our own impoverished soils in this country4 ,to many1 at first sight1 this seems to be in direct contradiction to our common belief1 and to point to the conclusion that the virgin soils of ,america are1 after all1 actually inferior in fertility to the soils of ,britain4 ,it is not1 however1 necessary to draw this conclusion1 as the facts of the case admit of another explanation4 ,the inferior returns obtained from ,american farms are due1 not to the fact that the ,american soil is less fertile than the ,british--for this is not true--but to the fact that it is less intensively cultivated4 ,in ,america land is cheap and labour is dear2 it is consequently found to be more economical to cultivate a large tract of land less thoroughly than a small area more thoroughly4 ,in ,britain the reverse is the case1 labour being cheap and land being dear4 ,it is thus necessary to make the land go as far as possible1 and produce as heavy a crop as it is possible to produce4 ,there can be little doubt1 that were ,american farming to be carried on as intensively as is ,british farming1 the present yield would be at least probably doubled4 ,we have now to consider the second class of properties which influence the fertility of a soil4 ,these are chemical4 ,,ii4 ,chemical ,composition of a ,soil4--,chemically considered1 the soil is a body of great complexity4 ,it is made up of a great variety of substances4 ,the relations existing between these substances and the plant are not all of equal importance2 some--and these form by far the largest proportion of the soil-substance--are concerned in acting simply as a mechanical support for the plant1 and in helping to maintain those physical properties in the soil which1 as we have just seen1 exercise such important functions in the plant's development4 ,fertilising ,ingredients4 ,a small portion of the soil-substance1 however1 takes a very much more active part in promoting plant-growth1 by acting as direct food of the plant4 ,as we have already seen in the ,introductory ,chapter1#ej the substances which have been found in the ash of plants are the following3 potash1 lime1 magnesia1 oxide of iron1 phosphoric acid1 sulphuric acid1 soda1 silica1 chlorine1 oxide of manganese1 lithia1 rubidia1 alumina1 oxide of copper1 bromine1 and iodine4 ,the general presence of some of these substances is doubtful2 the presence of others1 again1 probably purely accidental2 while some are only found in plants of a special nature1 as1 for instance1 iodine and bromine1 which are only found in the ash of marine plants4 ,of these ash constituents1 only the first six substances--those marked in italics--are absolutely necessary to plant-growth4 ,in addition to these six ash constituents1 the plant also derives its nitrogen1 which is a necessary plant-food1 chiefly from the soil4#ea ,importance of ,nitrogen1 ,phosphoric ,acid1 and ,potash4 ,but of these seven constituents of the soil which are necessary to plant-growth1 some have come to be regarded by the agriculturist with very much greater interest than others4 ,this is due to the fact that they are normally present in the soil in very much smaller quantities than is the case with the other equally necessary food ingredients2 that1 in short1 they are nearly invariably present in the soil1 in a readily available form1 in lesser quantities than the plant is able to avail itself of1 and often1 as in impoverished or barren soils1 in quantities too small for even normal growth4 ,these ingredients are nitrogen1 phosphoric acid1 and potash4#eb ,the importance of seeing that all the necessary plant ingredients are present in a soil in proper quantities will be at once properly estimated when it is stated that the absence or insufficiency in amount of one single ingredient is capable of preventing the growth of the plant1 although the other necessary ingredients may be even abundantly present4 ,with lime1 magnesia1 iron1 and sulphuric acid1 most soils are abundantly supplied4 ,the substances with which the farmer has to concern himself1 then1 are nitrogen1 phosphates1 and potash4 ,it is these substances therefore1 that1 as a rule1 are alone added as manures4 ,chemical ,condition of ,fertilising ,ingredients in ,soil4 ,but in considering the chemical properties of a soil1 a simple consideration of the quantity of the different ingredients present is not enough4 ,a very important consideration is their chemical condition4 ,ere any plant-food can be assimilated by the plant's roots1 it must first be rendered soluble4 ,the quantity of soluble1 or1 as it is known1 available1 plant-food in a soil is very small4 ,it is1 of course1 being steadily added to each day by the process of disintegration constantly going on in soils4 ,amount of ,soluble ,fertilising ,ingredients4 ,the exact nature and dissolving capacity of the soil-water1 charged as it is1 to a greater or less extent1 with different acids and salts1 as well as the dissolving power of the sap of the rootlets of the plant itself1 render the exact estimation of the available fertilising constituents wellnigh impossible4 ,an approximate estimate1 however1 may be obtained by treating the soil with pure water and dilute acid solutions4 ,the treatment of the soil with dilute acid solutions is for the purpose of simulating1 as nearly as may be done1 the conditions it is submitted to in the soil4 ,by treating a soil with water1 we obtain a certain amount of plant-food dissolved in the water4 ,this can only be regarded as indicating approximately the amount available at that moment to the plant4 ,but every day1 thanks to the numberless complicated reactions going on in the soil1 this soluble plant-food is constantly being added to4 ,considerations such as the above1 together with our ignorance as to the exact combinations in which the necessary minerals enter the plant1 will serve to indicate the great difficulty of this part of the subject4#ec ,value of ,chemical ,analysis of ,soils4 ,it is largely for these reasons that a chemical analysis of a soil is from one point of view of little value in giving evidence of its actual fertility4 ,what it demonstrates more satisfactorily is its potential fertility4 ,it is useful in revealing what there is present in it1 not necessarily1 however1 in an available condition4 ,under certain circumstances it may be made of great value1 as1 for example1 when we are anxious to know what will be the result of certain kinds of treatment1 such as the application of lime1 c4 ,it is hardly advisable1 therefore1 to place before the reader a number of soil analyses4 ,that he may obtain an approximate idea of the composition of a soil1 one or two representative analyses will be found in the ,appendix1#ed along with a short account of the chief minerals out of which soils are formed4 ,a point of considerable interest is the quantity per acre different soils contain of nitrogen1 phosphoric acid1 and potash4 ,although the amount of these ingredients when stated in percentage seems very trifling1 yet when calculated in lb4 per acre1 it is seen to be in large excess of the amount removed by the different crops4 ,this question will be dealt with in succeeding chapters4 ,a point of further interest is the chemical form in which the necessary plant constituents are present in the soil4 ,for information on this point the reader is referred to the ,appendix4#ee ,the third class of properties which affect the fertility of a soil are those which have been termed the biological4 ,,iii4 ,biological ,properties of a ,soil4--,the important functions which modern discoveries have shown to be discharged by minute organic life in the terrestrial economy are nowhere more strikingly exemplified than in the important role they perform in the soil4 ,bacteria of the ,soil4 ,the soil of every cultivated field is teeming with bacteria whose function is to aid in supplying plants with their necessary food4 ,the nature of1 and the functions performed by1 these organisms differ very widely4 ,regarding many of them we know very little2 every day1 however1 our knowledge is being extended by the laborious researches of investigators in all parts of the world1 and it is to be anticipated that ere long we shall be in possession of many facts regarding the nature and the method of the development of these most interesting agents in terrestrial economy4 ,that they are present1 however1 in enormous numbers in all soils we have every reason to believe1 one class of organism connected with the oxidation of carbonic acid gas being estimated to be present to the extent of over half a million in one gramme of soil#ef 7,wollny and ,adametz74 ,one class--and their importance is very great in agriculture--prepare the food of plants by decomposing the organic matter in the soil into such simple substances as are easily assimilated by the plant4 ,the so-called ripening of various organic fertilisers is effected1 we now know1 entirely through the agency of bacteria of this class4 ,plant-life is unable to live upon the complex nitrogenous compounds of the organic matter of the soil1 and were it not for bacteria these substances would remain unavailable4 ,attention will be drawn in the ,chapter on ,farmyard ,manure to this question more in detail4 ,of these bacteria1 among the most important are those which are the active agents in the process known as nitrification--i4e41 the process whereby organic nitrogen and ammonia salts are converted into nitrites and nitrates4 ,the presence of these organisms1 it would appear1 is indispensable to the fertility of any soil4 ,there are organisms1 on the other hand1 which have the power of reversing the work of the nitrification bacteria by converting nitrates into other forms of nitrogen4 ,the reduction of nitrates in the soil is often the source of much loss of valuable nitrogen1 which escapes in the free state1 so that the action of bacteria is not altogether of a beneficial nature4 ,three ,classes of ,organisms in the ,soil4 ,so far as the subject has been at present studied1 the micro-organisms in the soil may be divided into three classes4#eg ,first ,class of ,organisms4 ,we have1 first of all1 those whose function it is to oxidise the soil ingredients4 ,organisms of this class may act in different ways4 ,they may assimilate the organic matter of the soil and convert it into carbonic acid gas and water2 or1 on the other hand1 they may oxidise it by giving off oxygen4 ,some of these organisms1 whose action is of the first kind1 choose most remarkable materials for assimilation4 ,one has been found to require ferrous carbonate for its development1 which it oxidises into the oxide 7,winogradsky72 while another1#eh the so-called sulphur organism1 converts sulphur into sulphuretted hydrogen according to some1 and according to others into sulphates4 ,to this class of organism the nitrifying organisms belong4 ,as will be seen more fully in a subsequent chapter1 two distinct organisms connected with this process have already been isolated and studied--one of these effecting the formation of nitrites from organic nitrogen or ammonia salts1 and the other the conversion of nitrites into nitrates4 ,the second method in which these oxidising organisms act is by giving off oxygen4 ,there is much interest attaching to this fact1 as it was supposed till quite recently that all evolution of oxygen in vegetable physiology was dependent on the presence of light1 and also intimately connected with chlorophyll1 or the green colouring matter of plants4 ,it would seem1 however1 that among the soil organisms these conditions are not necessary1 and the evolution of oxygen may be carried on in the case of colourless organisms as well as in the case of light4 ,with organisms of this kind every soil is probably teeming4 ,a typical example is the organism which is the active agent in the oxidation of carbonic acid gas1 and which has already been referred to as existing in the soil in such numbers4#ei ,the ,second ,class of ,organisms in the ,soil4 ,the second class of organisms are those which reduce or destroy the soil constituents4 ,the most important of these1 from the agricultural point of view1 are those which effect the liberation of nitrogen from its compounds4 ,in the putrefaction of organic matter the organisms chiefly act1 it is probable1 in the entire absence of atmospheric oxygen2 but it would seem1 however1 that they may also act in the presence of oxygen4 ,it is through their agency that the soil may lose some of its nitrogen in the free form4 ,to this class belong the denitrifying organisms already referred to which reduce the nitrates and nitrites in the soil4#fj ,third ,class of ,organisms4 ,the third class of organisms are those by whose agency the soil is enriched4 ,of this class those fixing the free nitrogen from the air are the most important4 ,the nature of these organisms is still somewhat obscure1 but that leguminous plants have the power of drawing upon this source of nitrogen is now a firmly established fact4 ,further reference to these interesting organisms may be delayed to another chapter4 ,the important point to be emphasised is1 that for the healthy development of these organisms1 which are so necessary in every fertile soil1 certain conditions must exist4 ,these necessary conditions will be treated more in detail later on4 ,it is sufficient to notice that they have to do with the physical properties as well as the chemical composition of the soil4 ,this furnishes a further reason for the necessity of having the mechanical condition of a soil satisfactory4 ,recapitulation4 ,from what we have said1 it will be seen that the question of soil-fertility is a very complicated one1 and depends on numerous and varied conditions2 that the properties which constitute fertility1 while seemingly very widely different in their nature1 in reality influence one another to a very great extent2 that not merely is the presence in a soil of the necessary plant constituents necessary to fertility1 but that the possession by the soil of certain physical or mechanical properties is equally necessary2 while1 lastly1 we have seen that the presence of certain micro-organic life is bound up with the problem of fertility in a very direct and practical manner4 ,the importance of the conditions1 other than those of a purely chemical nature1 have been thus far somewhat prominently emphasised1 for the reason that in what follows attention will be almost exclusively devoted to the purely chemical conditions of fertility4 ,it is well1 then1 to realise that1 while the latter conditions are by far the most important1 so far as the farmer is practically concerned1 inasmuch as they are most under his control1 they are not the only conditions1 and are not by themselves able to control fertility4 ,,footnotes3 #cc ,this statement perhaps needs qualification4 ,while the important role played by the physical qualities of the soil were in the early years of the science recognised1 of more recent years the chemical composition of the soil has been engaging almost exclusive investigation4 ,physical properties of the soil have recently acquired a further importance in the eyes of the agricultural chemist1 from the important influence they exert on what we have here called the biological properties of a soil--viz41 the development of those fermentative processes whereby plant-food is prepared to a large extent4 #cd ,a good example of the absorptive capacity of a soil containing a large quantity of vegetable matter is furnished by peat-bogs1 which1 sponge-like1 can absorb enormous quantities of water4 7,see ,appendix1 ,note ,i41 p4 #ih47 #ce ,jethro ,tull1 an early well-known agricultural writer1 who lived about the middle of last century1 propounded the theory1 that as the food of plants consisted of the minute earthy particles of the soil1 all that was required by the skilful farmer was to see that his soil was properly tilled4 ,he accordingly published a work entitled ',horse-hoeing ,husbandry1' in which he advocated a system of thorough tillage4 7,see ,historical ,introduction1 p4 #aj47 #cf ,see ,introduction1 p4 #ee4 #cg ,see ,introductory ,chapter1 p4 #ee4 #ch ,it is not exactly known why excess of water should prevent normal growth in the plant4 ,probably it is on account of the fact that free access of oxygen is hindered in such a case4 ,the roots are thus not freely enough exposed to this necessary gas1 and fermentative processes of the nature of nitrification are not promoted4 ,it may be also due to the fact that the solution of plant-food is too dilute when such excess of water prevails4 #ci ,see ,appendix1 ,note ,,ii41 p4 #ih4 #dj ,some experiments by ,e4 ,wollny show this4 ,he found1 when experimenting with summer rape1 that the best results were obtained when the soil contained only #dj per cent of its total water-holding power2 when the amount was either lessened or increased the results obtained fell off4 ,the effect of either too little or too much water is seen in the development of the different organs of the plant as well as on its period of growth1 much water seeming to retard the growth4 ,the quality of the plant seems also to be influenced by this condition4 ,experiments on cereal grains by ,wollny show that not merely is the texture of the grain influenced1 but that much moisture lessens the percentage of nitrogen4 ,wollny is of the opinion that for crops generally1 the best amount is from #dj to #ge per cent of the total water-holding capacity of the soil4 #da ,see ,appendix1 ,note ,,iii41 p4 #ii4 #db ,see p4 #ee4 #dc ,the effect of the temperature of the soil on the development of the plant is most important4 ,this is especially marked at the period of germination1 but is felt at subsequent periods of growth4 ,up to a certain temperature the warmer the soil the more rapid the plant's development4 ,in this country the temperature most favourable to growth is rarely exceeded1 or indeed reached4 #dd ,see ,chapter on ,farmyard ,manure4 #de ,as will be seen further on1 the fermentation of organic substances is caused by the action of micro-organic life4 #df ,see ,appendix1 ,note ,,iv41 p4 #ajj4 #dg ,of course it must be remembered that a large amount of carbonic acid in soils comes from the decay of vegetable matter4 ,soils are twenty to one hundred times richer in carbonic acid than the air4 #dh ,see ,chapter ,,iii41 p4 #aai4 #di ,see ,introduction1 p4 #dj4 #ej ,see ,introductory ,chapter1 p4 #ed4 #ea ,see pp4 #dd and #ace4 #eb ,occasionally also lime4 #ec ,see ,appendix1 ,notes ,v4 and ,,vi41 pp4 #ajj1 #aja4 #ed ,note ,,vi41 p4 #aja4 #ee ,note ,,vii41 p4 #ajg4 #ef ,even larger estimates of the number of germs in a gramme of soil have been made--from three-quarters to one million 7,koch1 ,fuelles1 and others74 #eg ,these organisms consist of molds1 yeast1 and bacteria1 the last-named being most abundant4 ,in the surface-soil1 among the bacteria1 bacilli are most abundant4 ,micrococei are not abundant4 #eh ,investigated by ,winogradsky1 ,olivier1 ,de ,rey ,pailhade1 and others4 #ei ,organisms of this kind have been investigated among others by ,heraues1 ,hueppe1 and ,e4 ,wollny4 ,according to the two first-mentioned investigators1 certain colourless bacteria effect the formation in the absence of light from humus and carbonates a body resembling in its nature cellulose4 #fj ,investigated by ,springer1 ,gayon and ,dupetit1 ,deherain1 and ,marguenne4 ,,appendix ,,to ,,chapter ,i4 ,,note ,i4 7p4 #fh74 ,the following determinations by ,schuebler show the absorptive power of different kinds of soil-substances4 ,these were obtained by soaking weighed quantities of the soil in water1 and allowing the excess of liquid to drain away1 and weighing the wet earth4 ,per cent of water absorbed by #ajj parts of earth4 ,siliceous sand #be ,gypsum #bg ,calcareous sand #bi ,sandy clay #dj ,strong clay #ej ,arable soil #eb ,fine calcareous #he ,garden-earth #hi ,humus #aij ,it has been calculated that the absorptive power of a mixture of different substances is not simply equal to the sum of their separate ingredients4 ,,note ,,ii4 7p4 #gd74 ,,evaporation4 ,the retentive property of a soil for water tends to retard evaporation4 ,the following table by ,schuebler shows the rate at which evaporation proceeds in different soils4 ,the experiment was conducted in the following way4 ,the soil experimented upon was saturated with water and spread over a disc1 and allowed to evaporate for four hours1 when it was weighed4 ,the amount of time required for the evaporation of #ij per cent of the water was also estimated4 ,of #ajj parts of water in the wet soil there evaporated1 at #fj deg4 ,fahr4-- ,time required to ,in four hours-- evaporate #ij per cent4 ,from-- per cent4 ,hours4 ,minutes4 ,quartz #hh #d #d ,limestone #gf #d #dd ,sandy clay #eb #e #a ,stiffish clay #df #f #ee ,loamy clay #df #g #eb ,pure grey clay #cb #aa #ag ,loam #cb #aa #ae ,fine calcium carbonate #bh #ab #ea ,humus #ba #ag #cc ,magnesium carbonate #aa #cc #bj ,,note ,,iii4 7p4 #gf74 ,,hygroscopic ,,power ,,of ,,soils4 ,davy found the hygroscopic power of soils to be as follows4 ,he found that #ajj parts by weight of three samples of different sands absorbed #c1 #h1 and #aa parts of water1 respectively1 in one hour2 while three loams absorbed similarly #a4c1 #a4f1 and #a4h parts4 ,the following samples of soil were dried at #bab deg4 ,fahr41 and exposed to an atmosphere saturated with water and a temperature of #fb deg4 ,fahr41 when it was found they absorbed the following amounts in twelve hours' time3-- ,quartz sand #j4j ,limestone sand #j4c ,lean clay #b4a ,fat clay #b4e ,clay soil4 #c4j ,pure clay4 #c4g ,garden-loam #c4e ,humus #h4j ,,note ,,iv4 7p4 #ha74 ,,gases ,,present ,,in ,,soils4 ,the air which we find enclosed in the pores of the soil is distinctly poorer in oxygen than ordinary air4 ,boussingault found the percentage of oxygen in a sandy soil1 freshly manured and wet with rain1 to be as low as #aj4ce per cent2 while the air in forest-soil contained #ai4e per cent of oxygen1 and 4#ic per cent of carbonic acid4 ,the percentage of oxygen in soils depends on the rate of decay of the organic portions4 ,the depth of the soil-layer also determines the quantity4 ,this is owing to the fact that diffusion takes place more slowly deep down than near the surface4 ,,note ,v4 7p4 #ij74 ,,amount ,,of ,,soluble ,,plant-,,food ,,in ,,the ,,soil4 ,two of the most reliable methods of ascertaining an approximation of the quantity of soluble soil constituents are 7#a7 by treating the soil with distilled water1 and 7#b7 by analysing the drainage-water4 ,with regard to the former of these two methods1 it has been found that even the amount of fertilising matter dissolved out by pure distilled water varies4 ,this variation depends on the amount of distilled water used1 as well as the length of time the soil is left in contact with the solvent4 ,by washing the soil with different quantities of water1 different amounts of soluble soil ingredients will be found to have been washed out2 for although the first washings contain by far the greater portion of the soluble matter1 each subsequent washing will be found to contain further quantities4 ,a number of experiments have shown that #ajjj parts of distilled water dissolved out from different soils from one half to one and a half parts of soluble constituents2 or from 4#je to 4#ae per cent4 ,of this soluble matter from #cj to #fg per cent is mineral in its nature1 and from #cc to #gj per cent organic4 ,poor sandy soils yield the minimum quantity1 while peaty soils yield the maximum4 ,the quantity of soluble matter in a regular peaty soil may vary from 4#d to #a4d per cent2 this consists chiefly1 however1 of organic matter4 7,see ,johnson's ',how ,crops ,feed1' p4 #cab47 ,perhaps a more satisfactory method is by analysing the drainage-water of a soil4 ,this has been found to vary very considerably in composition4 ,the average of a large number of analyses are 4#jd to 4#je per cent of dissolved matter4 ,of this dissolved matter the largest proportion is made up of organic matter1 nitric acid1 lime1 and soda salts4 ,it must be borne in mind1 however1 that even the drainage-water does not furnish an exact indication of the amount of dissolved matter in a soil4 ,much1 perhaps the largest proportion of dissolved matter1 never finds its way into the drainage-water4 ,that contained by the drainage-water really represents the surplus quantity of dissolved matter which the soil is unable to retain1 and which is thus washed by the rain into the drains4 ,the composition of drainage-water is interesting1 as it shows that1 practically speaking1 all the necessary plant ingredients are in a state of solution in the soil4 ,,note ,,vi4 7p4 #ij74 ,,chemical ,,composition ,,of ,,the ,,soil4 ,the most important substances present in soils are as follows3 silica1 alumina1 lime1 magnesia1 potash1 soda1 ferric oxide1 manganese oxide1 sulphuric acid1 phosphoric acid1 and chlorine4 ,of these substances the presence of alumina1 silica1 lime1 and1 in certain cases1 magnesia1 along with the organic portion of the soil--the humus--has the chief influence in determining the nature and the physical properties of a soil4 ,in order to clearly understand to what it is soils owe the nature of their chemical composition1 it is necessary to consider the composition of some of the chief minerals out of the disintegration of which soils are formed4 ,while we know of some seventy elements present in the earth's crust1 it is practically made up of only some sixteen4 ,these sixteen are--oxygen1 silicon1 carbon1 sulphur1 hydrogen1 chlorine1 phosphorus1 iron1 aluminium1 calcium1 magnesium1 sodium1 potassium1 fluorine1 manganese1 and barium4#fa ,of these1 oxygen is by far the largest constituent1 forming1 roughly speaking1 about #ej per cent4 ,the main mass of the rocks consists of silica1 and this is generally combined with alumina1 as in clay1 forming aluminium silicate1 and with the commoner alkalies and alkaline earths4 ,another extremely abundant compound is carbonate of lime1 which1 as limestone1 chalk1 and marl1 forms one-sixth of the earth's total rocks4 ,the word mineral means a definite chemical compound of natural occurrence4 ,the number of minerals is very great1 and it is impossible to go into the subject here4 ,reference can only be made to a few of the more prominent ones1 which are chiefly concerned in the formation of soils4 ,those formed out of silicates are1 from the agricultural point of view1 the most important1 as they form a very large group2 and it is by their disintegration that soils are chiefly formed4 ,they consist of silica and alumina1 along with various other substances1 chiefly alkalies and alkaline earths4 ,it is important to note one peculiarity about the solubility of silicates4 ,we have two classes of silicates3 the one1 which is called acid1 and contains an excess of silica2 the other1 basic1 and which contains an excess of base4 ,now1 while the former of these is more or less insoluble1 the second is soluble4 ,this fact has an important signification in the process of the disintegration of the silicate minerals we are about to consider4 ,the first and most important class are the ,felspars4 ,felspar is not really a definite mineral1 with a definite chemical composition1 but rather the name of a class of minerals of which there are several different kinds4 ,the felspars are composed of silica and alumina1 along with potash1 soda1 and lime1 with traces of iron and magnesia4 ,their principal constituents1 however1 are silica and alumina1 along with either potash1 soda1 or lime4 ,according as the base potash1 soda1 or lime predominates1 the felspar is known as ,orthoclase1 ,albite1 and ,oligoclase1 respectively4 ,the following are the analyses of the three minerals 7by the late ,dr ,anderson73-- ---------------------------------------- ------------------------------- ,orthoclase4 ,albite4 ,oligoclase4 ---------------------------------------- -------- #a4 #b4 #a4 #b4 #a4 #b4 ---------------------------------------- ---------------------------- ,silica #fe4gb #fe4jj #fg4ii #fh4bc #fb4gj #fc4ea ,alumina #ah4eg #ah4fd #ai4fa #ah4cj #bc4hj #bc4ji ,peroxide of iron traces #j4hc #j4gj #a4ja #j4fb none ,oxide of manganese traces #j4ac none none none none ,lime #j4cd #a4bc #j4ff #a4bf #d4fj #b4dd ,magnesia #j4aj #a4jc none #j4ea #j4jb #j4gg ,potash #ad4jb #i4ab none #b4ec #a4je #b4ai ,soda4 #a4be #c4di #aa4ab #g4ii #h4jj #i4cg ---------------------------------------- ---------------------------- #ajj4jj #ii4dg #ajj4jh #ii4hc #ajj4gi #aja4cg ---------------------------------------- ---------------------------- ,according as these various felspars are present in a soil1 so will the quality of the soil be4 ,it stands to reason that as the presence of potash in a soil is one of the distinguishing features of its fertility1 much will depend on the extent to which the orthoclase felspar is present2 and also1 not only on the extent1 but on the state and degree of its disintegration4 ,it is important to note the method of this disintegration4 ,it is effected by the absorption of water4 ,this water is not merely absorbed mechanically1 but actually enters into the composition of the mineral4 ,it is not present as moisture merely1 capable of being expelled at ordinary boiling temperature1 but it forms what is known as water of composition4 ,in this process of hydration1 the mineral loses its lustre and crystalline appearance1 crumbles away into a more or less--according to its state of disintegration--powdery mass4 ,a very great change is also effected in its chemical composition2 it loses nearly all its base4 ,this is effected in the following way4 ,as water enters into the mineral's composition1 it sets free a certain portion of the base2 there is thus formed a basic silicate1 which1 being soluble in water1 is washed away in solution4 ,this change may be illustrated by quoting the analysis of a kaolin clay formed by the disintegration of orthoclase felspar4 ,kaolin ,clay formed by disintegration of ,orthoclase4 ,silica #df4hj ,alumina #cf4hc ,peroxide of iron #c4aa ,carbonate of lime #j4ee ,potash #j4bg ,water #ab4dd ------ #ajj4jj ------ ,the chief difference here is the almost total loss of potash and a portion of the silica1 and the gain of water4 ,the other constituents practically remain insoluble4 ,another important mineral is ,mica4 ,its composition is not unlike felspar4 ,it contains silica1 alumina1 and iron1 in considerable quantities1 also magnesia and potash4 ,there are two kinds of mica--that containing potash1 and that containing magnesia1 in excess4 ,the analyses of these two kinds are as follows 7by the late ,dr ,anderson73-- ,,micas4 7a7 ,potash4 7b7 ,magnesia4 ,silica #df4cf #db4fe ,alumina #cf4hj #ab4if ,peroxide of iron #d4ec none ,protoxide of iron none #g4aa ,oxide of manganese #j4jb #a4jf ,magnesia none #be4ge ,potash #i4bb #f4jc ,hydrofluoric acid #j4gj #j4fb ,water #a4hd #c4ag ----- ----- #ii4dg #ii4ce ----- ----- ,the decomposition of mica is very slow1 however1 as it is a peculiarly hard mineral4 ,other important minerals are ,hornblende and ,augite4 ,these are composed of silica1 alumina1 iron oxide1 manganese oxide1 lime and magnesia4 ,these are the chief minerals out of which soils are formed4 ,it is scarcely necessary to say that few soils are made up out of any of these three minerals alone4 ,nearly all rocks are formed out of a mixture of these minerals4 ,where1 however1 any one mineral predominates over the rest1 the nature of the soil will be thereby affected4 ,in order to illustrate this1 it may be well to mention the composition of one or two of the commoner rocks4 #a4 ,granite1 which is so abundant in certain parts of the north of ,scotland1 and which gives rise to the soils in the neighbourhood of ,aberdeen1 is made up of a mixture of quartz1 felspar1 and mica4 ,it depends on the felspar present--i4e41 whether it is orthoclase1 oligoclase1 or albite--whether the soil will be rich in potash or not4 ,granite containing orthoclase felspar produces a fairly fertile soil4 ,an important consideration1 which is apt to complicate this question1 is the situation of such soils4 ,they are generally so high above sea-level1 that their fertility is seriously impaired on these grounds4 #b4 ,gneiss1 another common rock1 is similar in composition1 only that it contains very little felspar1 and a correspondingly greater amount of mica4 #c4 ,syenite contains quartz1 felspar1 and hornblende4 ,the rocks of which greenstone and trap are types1 are found very largely scattered over the country4 ,they are of two kinds1 diorite and dolorite4 #d4 ,limestone is of two great classes4 ,we have 7#a7 ,common1 7#b7 ,magnesian4 ,the following are the analyses of these two classes by ,dr ,anderson3-- ---------------------------------------- --------------------------------- ,common4 ,magnesian4 ---------------------------------------- --------- ,mid-,lothian ,sutherland4 ,sutherland4 ,dumfries4 ---------------------------------------- ------------------------------- ,silica #b4jj #g4dc #f4jj #b4ca ,iron oxide and alumina #j4de #j4gf #a4eg #b4jj ,carbonate of lime #ic4fa #hd4aa #ej4ba #eh4ha ,carbonate of magnesia #a4fb #g4de #da4bb #cf4da ,phosphate of lime #j4ef - - - ,sulphate of lime #j4ib - - - ,organic matter #j4bj - - - ,water #j4ej - - - ----- ----- ----- ----- #ii4hf #ii4ge #ii4jj #ii4ec ---------------------------------------- ------------------------------- ,clays are formed by the disintegration of any of the crystalline rocks2 the purest clays being formed from felspar4 ,a pure clay consists simply of silica and alumina1 all the other constituents having been washed out4 ,disintegration1 however1 seldom reaches such an extent2 otherwise clay soils would be completely barren1 which they are notably not4 ,the impurities present in clay1 which consist of alkalies1 especially potash and other mineral ingredients of the plant1 are what confer on clay soils their fertility4 ,clays differ1 however1 very considerably in their composition4 ,the following is an analysis of a clay soil by ,dr ,anderson3-- ,silica #fj4jc ,alumina #ad4ia ,peroxide of iron #h4id ,lime #b4jh ,magnesia #d4bb ,potash #c4hg ,soda #j4jf ,water and carbonic acid #e4fg ----- #ii4gb ----- ,,note ,,vii4 7p4 #ia74 ,,forms ,,in ,,which ,,plant-,,foods ,,are ,,present ,,in ,,soil4 ,the forms in which the bases necessary for plant-food are present in the soil1 are chiefly as hydrated silicates1 and in combination with organic acids1 forming humates1 c41 as well as in the form of sulphates and chlorides4 ,phosphoric acid is present in combination with iron1 alumina1 or lime1 or possibly also as magnesium-ammonium-phosphate4 ,sulphuric acid is generally present in a more or less insoluble condition1 in combination with iron and lime2 whereas chlorine is combined with the alkali bases in an easily soluble form4 ,an important point is as to the form in which the plant absorbs these food constituents4 ,in this connection reference may be made to a theory put forward by a very distinguished ,french agricultural chemist1 ,professor ,grandeau4 ,his theory is that the necessary ingredients of plant-food are absorbed into the plant as humates1 or1 at any rate1 that the medium of this transference is humic acid1 and organic acids of a similar nature4 ,this theory1 however1 while ingenious1 has not yet been supported by sufficient evidence to make its acceptance advisable4 ,it is probable that it is only in the form of soluble salts that the plant can absorb its food4 ,it is quite probable1 however1 at the same time1 that the exact form in which the different food substances enter the plant may be largely determined by circumstances4 ,according to ,nobbe1 chloride of potassium is the most suitable form of potassium salts1 although the plant may absorb its potassium as sulphate1 phosphate1 or even silicate4 ,,footnotes3 #fa ,composition of the earth's solid crust in #ajj parts by weight3-- ,oxygen #dd4j to #dh4g ,calcium #f4f to #j4i ,silicon #bb4h to #cf4b ,magnesium #b4g to #j4a ,aluminium #i4i to #f4a ,sodium #b4d to #b4e ,iron #i4i to #b4d ,potassium #a4g to #c4a 7,roscoe's ',lessons in ,elementary ,chemistry1' p4 #h47 ,,chapter ,,ii4 ,,functions ,,performed ,,by ,,manures4 ,having now considered the general conditions on which fertility of soil depends1 we are in a position to deal with the nature and function of manures4 ,manures may be classified in several different ways1 and a considerable amount of confusion is sometimes caused by the variety of classification adopted by different writers on this subject4 ,etymological meaning of the word ,manure4 ,let us1 in the first place1 clearly understand what we mean by a manure4 ,the word manure comes from the ,french word manoeuvrer1 which simply means to work with the hand1 hence to till1 and this etymological meaning of the word illustrates the old belief in the function of manures4 ,we have already seen in the historical introduction that1 according to ,tull1 the true and only function of manures was to aid in the pulverisation of the soil by fermentation4 ,in advancing his system of thorough tillage1 he claimed that since tillage effected the pulverisation of the soil1 where it was practised1 manures could be dispensed with4 ,definition of ,manures4 ,we no longer1 of course1 attach this old meaning to the word4 ,the word manure is now applied to any substance which by its application contributes to the fertility of a soil4 ,as has been shown in the previous chapter1 the substances necessary for plant-growth which are apt to be lacking in a soil1 are only generally three in number--viz41 nitrogen1 phosphoric acid1 and potash4 ,a manure1 therefore1 is understood to be any substance containing these ingredients1 either singly or together1 and its commercial value is determined by the amount it contains of these substances4 ,but while this is so1 it must not be forgotten that if we define a manure to be a substance which contributes in any way to the fertility of the soil1 substances other than these above mentioned may be fairly regarded as manures4 ,the fertility of a soil1 we have seen1 depends not merely on the presence of certain constituents1 but also on their chemical condition--i4e41 whether they are easily soluble or not4 ,it further depends1 as we have also seen1 on the possession by the soil of certain mechanical and biological properties4 ,thus there are substances which act upon the soil's inert fertilising matter1 and by their action convert it into a more speedily available form4 ,there are other substances which by their application exert a considerable effect on the texture of the soil1 and thereby influence its physical and biological properties4 ,all such substances1 according to the above definition of a manure1 must be included under the term4 ,it will thus be seen that since fertility in a soil can be promoted in a variety of ways1 and the functions performed by manures are of different kinds1 we can divide them into different classes1 according to their respective action4 ,different ,classes of ,manures4 ,in the first place1 we can divide manures into two great classes1--7#a7 those supplying to the soil necessary plant-food constituents1 and thus contributing directly to fertility2 and 7#b7 those influencing soil-fertility in an indirect manner4 ,the first class we may call direct manures1 and the second indirect4 ,those two classes admit further of being subdivided into other smaller classes4 ,among the direct manures we have a number of subdivisions in use4 ,they may be divided into general manures and special manures1 according as they contain all the elements necessary for plant-growth1 or only some of them2 or they may be divided according to their source into natural and artificial1 mineral and vegetable4 ,similarly we have a number of subdivisions among the second class1 depending on the special nature of the action they exert4 ,some manures act in both capacities--both directly and indirectly--and in order that their value be fully appreciated must be studied under both heads4 ,the most striking example of such a manure is farmyard manure4 ,there are other manures which may in certain circumstances act in two different ways4 ,such a substance is lime4 ,there are soils which are actually lacking in a sufficiency of lime for the needs of crops4 ,on such soils an application of lime would act both as a direct and also as an indirect manure4 ,there may also be cases of an exceptional nature1 in which magnesia salts or even iron salts may act as direct manures4 ,many manures commonly regarded as purely direct manures would exert an indirect influence were the quantities in which they were applied sufficiently large4 ,this is the case1 indeed1 with many artificial manures1 such as guano1 bones1 nitrate of soda1 and basic slag4 ,it has been claimed for nitrate of soda that it not merely promotes fertility by supplying nitrogen in its most available form to the soil1 but that the soda it contains exerts a valuable indirect influence in consolidating the soil and increasing its absorptive powers4 ,when we reflect1 however1 on the small quantity of this manure which is applied per acre1 its mechanical influence must be insignificant4 ,the same applies to basic slag1 which contains a considerable quantity of free lime in its composition4 ,as this manure1 however1 is sometimes applied in considerable quantities1 it is reasonable to suppose that its indirect value may not be altogether insignificant4 ,indeed we have proof of this in the fact that its most favourable action has been found to be on soils rich in organic matter4#fb ,the action of bones and guano1 and indeed of all other manures containing a large percentage of decomposable organic matter1 is likewise of a double nature1 inasmuch as their decomposition or putrefaction in the soil gives rise to the formation of carbonic and organic acids1 which are capable of exerting a chemical action on the soil ingredients4 ,there is one point in connection with the action of these manures which is worthy of notice1 and it is that1 however slight their indirect value may be1 their action as a direct manure is very much accelerated by the way in which their organic matter putrefies4 ,in short1 they may be described as providing1 to a certain extent1 the solvents which render them available for the requirements of the plant4 ,it may be here convenient to classify the manures which we intend subsequently to deal with4 ,i4 ,manures1 action of which is both direct and indirect--e4g41 green manures1 farmyard manure1 composts1 and sewage4 ,,ii4 ,manures which may be regarded as having only a direct action--e4g41 guano of all kinds1 bones in all forms1 nitrate of soda1 sulphate of ammonia1 dried blood1 superphosphates1 mineral phosphates of all kinds1 horns and hoofs1 shoddy1 wool-waste1 fish-guano1 muriate of potash1 sulphate of potash1 and kainit4 ,,iii4 ,manures which may be regarded as having only an indirect value--e4g41 lime1 mild and caustic1 marl1 gypsum1 salt1 c4 ,we shall now proceed to discuss the nature and action of these different manures1 starting with those exercising both a direct and indirect influence4 ,before doing so it may be well to consider the occurrence and natural sources of the three important soil constituents1 nitrogen1 phosphoric acid1 and potash1 with a view of seeing to what extent these are being removed from our soils by the various natural processes constantly going on1 as well as by the crops1 and how far their natural sources are capable of making good this loss--in short1 to clearly understand the economic reasons for the application of artificial manures4 ,,footnotes3 #fb ,see ,chapter on ,basic ,slag4 ,,chapter ,,iii4 ,,the ,,position ,,of ,,nitrogen ,,in ,,agriculture4 ,of manurial ingredients1 nitrogen is by far the most important1 and on the presence and character of the nitrogen it contains1 the fertility of a soil may be said to be most largely dependent4 ,most soils1 as a rule1 are better supplied with available ash ingredients than with available nitrogen compounds4 ,the expensive nature of most artificial nitrogenous manures also gives to nitrogen the first position from an economic point of view4 ,a thorough study1 therefore1 of the different forms in which it exists in nature1 of the numerous and complicated changes it undergoes in the soil1 by which it is prepared for the plant's needs1 of the relation of its different forms to plant-life1 and of the natural sources of its loss and gain1 is of the highest importance if we are to hope to understand the difficult question of soil-fertility4 ,the ,rothamsted ,experiments and the ,nitrogen question4 ,the position of nitrogen in agriculture is a question of great difficulty and complexity4 ,it has engaged much attention1 and has had devoted to its elucidation much elaborate and painstaking research4 ,to the ,rothamsted experiments we owe most of the information we possess on the subject1 and the facts contained in this chapter are almost entirely derived from the results of these famous experiments1 as embodied in the memoirs and writings of ,messrs ,lawes1 ,gilbert1 and ,warington4 ,different forms in which ,nitrogen exists in ,nature4 ,we have already referred to the nitrogen question in the historical introduction4 ,in order1 however1 to have a comprehensive view of the subject1 it may be well to recapitulate some of the facts there mentioned4 ,nitrogen1 as we have already seen1 exists in the free or elementary condition1 as nitrates and nitrites1 as ammonia1 and in a large number of different organic forms4 ,nitrogen in the ,air4 ,it occurs in greatest abundance 7amounting to about #hj per cent7 in the first of these forms in the air4 ,that this free nitrogen1 which is practically unlimited in quantity1#fc has originally been the source of all its other forms1 is of course obvious4 ,but this conversion of free nitrogen into the various compound forms in which it occurs throughout the mineral1 vegetable1 and animal kingdoms1 has been a process effected by a variety of indirect methods1 and only at the expense of a vast amount of time4 ,for practical purposes1 the free nitrogen of the air may be regarded chiefly as a non-available source for most bodies containing it4 ,it may be described as of all forms of nitrogen the least active1 as far as plant-life is concerned4 ,relation of free ,nitrogen to the ,plant4 ,the relation of the free nitrogen to the plant has formed the subject of much research1 more especially during the last few years1 and a brief epitome of the main results arrived at has already been given in the ,introductory ,chapter4#fd ,that this source of nitrogen is not so inaccessible to the plant as was formerly believed1 has now been abundantly proved4 ,as the considerations which have led to this conclusion1 and have suggested the very recent elaborate experiments on the fixation of free nitrogen by the plant--the results of which bid fair1 it would seem1 to largely revolutionise our agricultural practice--have been due to the study of the relation of the soil-nitrogen to the plant1 it will be best to defer further discussion of this question till we have dealt with the other sources of nitrogen4 ,combined ,nitrogen in the ,air4 ,in addition to nitrogen in the free state1 air contains very small quantities of this element in combined forms4 ,we have it in minute traces as nitrates and nitrites1 as ammonia1#fe and also in still smaller traces as organic nitrogen in the minute dust-particles which modern researches have revealed as being present in such enormous numbers in our atmosphere4 ,what the sources of these nitrates and nitrites 7which exist in quantities so minute that accurate determination of their amount is rendered extremely difficult7 are is a disputed point4 ,that nitrogen and oxygen unite together to form nitric and nitrous oxides under the influence of intense heat1 such as the electric spark1 has been proved beyond doubt4 ,one source1 therefore1 is probably the electrical discharges which are taking place more or less frequently on different parts of the earth's surface4 ,nitrates may also be formed in the combustion of nitrogenous bodies4#ff ,in the burning of coal-gas1 for example1 it is probable that small quantities of nitrates may be produced4 ,similarly the slow combustion or decay of nitrogenous organic matter1 which constantly takes place all over the earth's surface1 may be regarded as another source of this form of combined nitrogen4 ,ammonia may be similarly formed by the combustion1 either quick or slow1 of nitrogenous organic matter4 ,it exists in the air as nitrate or nitrite of ammonia1 and also as carbonate of ammonia4#fg ,amount of combined ,nitrogen falling in the ,rain4 ,the importance of the combined nitrogen in the air as a source of soil-nitrogen is best gauged by the amount falling annually on the soil dissolved in rain4 ,this has been found to vary considerably4 ,in the rain falling in the vicinity of large towns the amount is greater than in rain falling in the country4 ,thus at ,rothamsted1 in ,england1 the average amount for several years was only #c4cg lb4 nitrogen per annum per acre1 of which #b4ec lb4 were as ammonia14#hd being as nitric acid4 ,at ,lincoln1 in ,new ,zealand1 #a4gd lb4 fell annually per acre--as ammonia14#gd1 as nitric acid1 #a4jj2 while at ,barbadoes the amount was #c4gg lb41 of which 4#ic was as ammonia1 and #b4hd as nitric acid4#fh ,that the combined nitrogen derived from the air by the soil may be considerably in excess of this is highly probable4 ,soils1 especially when damp1 may absorb much larger quantities from the air of the combined nitrogen it contains4 ,we must remember that the air in contact with the soil-surface is constantly being changed1 and that there is thus a constant renewal of the air passed over the ground4 ,the result is that the amount of air from which combined nitrogen may be removed is very great4#fi ,nitrogen in the ,soil4 ,it has been remarked as a fact worthy of notice that nitrogen is essentially a superficial element4 ,by this is meant that it is only found1 as a rule1 on the earth's immediate surface4 ,this statement can only be admitted to be true within certain limits4 ,the chief source of nitrogen1 in addition to the atmosphere1 is1 of course1 vegetable and animal tissue4#gj ,as vegetable and animal tissue are only found to any extent on the earth's surface1 nitrogen is therefore chiefly found there4 ,the natural deposits of nitrogen salts1 such as the nitrate-fields of ,chili and the saltpetre soils of ,india1 c41 also only occur superficially4 ,notwithstanding these facts1 however1 the amount of nitrogen which exists at probably considerable depths from the surface must be very great4 ,there are few sedimentary rocks which do not contain it4 ,at ,rothamsted a sample of calcareous clay1 taken from a depth of #ejj feet1 contained 4#jd per cent--that is1 as much as is found1 on an average1 in the ,rothamsted clay subsoils4 ,nitrogen in the ,subsoil4 ,on the whole1 however1 as we have said1 nitrogen is chiefly found in the surface-soil4 ,the amount found in the subsoil at ,rothamsted seems to vary very slightly at different depths1 the percentage amounting to from 4#jf to 4#jc4ga ,unlike the nitrogen of the surface-soil1 that in the subsoil seems to be of very ancient origin1 being probably derived from the remains of animal and vegetable life in the mud deposited at the bottom of the ocean4 ,it is more abundant in the case of a clay subsoil than in a sandy subsoil4 ,nitrogen of ,surface-,soil4 ,nitrogen has a tendency to collect on the top layers of the surface-soil1 the first #i inches or foot containing by far the largest proportion of it4 ,in the table given in the ,appendix1#gb the rate at which it decreases in amount the further down we go is clearly shown4 ,determinations of the respective amounts of nitrogen in every #c inches of the soil1 taken to a depth of one foot of the experimental wheat-field at ,rothamsted1 showed that the percentage between the first #c inches and the second #c inches varied very slightly4 ,a more marked difference1 however1 was shown to exist between the nitrogen in the second and third #c inches2 while the fourth #c inches were distinctly poorer--differing very little in their percentage of nitrogen from the subsoil4 ,this was the case in unmanured soil4 ,in the case of heavily manured soil1 the increase in the soil's percentage1 due to manure1 was shown to be felt to the depth of a foot1 but not much below it4#gc ,a careful perusal of the tables in the ,appendix will show that the quantity of nitrogen in the case of both arable and pasture soils steadily decreases for the first #c feet1 but that below this depth little decrease is seen1 the percentage evidently becoming fairly constant4 ,the amount of ,nitrogen in the ,soil4 ,very considerable difference exists in the amount of nitrogen present in different soils4 ,the majority of analyses refer only to the amount found in the surface-soil--generally in the first #i or #ab inches4 ,as the soil1 further1 is not a body exactly homogeneous in its character1 very considerable difficulty exists in obtaining reliable results4 ,a great deal depends1 therefore1 on the method of sampling and the basis of calculation adopted2 and it may be that this may occasionally explain1 to some extent at least1 the great discrepancies in the estimation of the quantities of nitrogen present in different soils as found by different investigators4 ,peat-soils richest in ,nitrogen4 ,of all soils1 peat-soils are richest in nitrogen4 ,professor ,s4 ,w4 ,johnson found the nitrogen in fifty separate samples of peat to range from 4#d per cent to #b4i per cent1 the average being #a4e per cent4 ,on the other hand1 marls and sandy soils are poorest1 the analyses of a number of these soils showing only from 4#jjd to 4#jhc per cent for the former1 and 4#jbe to 4#jgd for the latter4 ,as a general rule most arable soils contain over one-tenth per cent of nitrogen1 or1 say1 over #cejj lb4 per acre4 ,a good pasture-soil1 taken to a depth of #i inches at ,rothamsted1 was found to contain about a quarter per cent4 ,in ten samples of soil1 taken to a depth of #i inches1 from different parts of ,great ,britain and ,ireland1 ,munro found from 4#abh to 4#fie per cent of nitrogen1 the average being 4#cbgh per cent4 ,the ,rothamsted soils1 it may be pointed out1 are probably poor in nitrogen compared with most soils4 ,a4 ,mueller's investigations showed that in some of the soils he has analysed1 the nitrogen amounted to little short of one per cent1 while for the others the average was over half a per cent2 even the poorer soils he examined contained about one quarter per cent on an average4 ,anderson's analyses of ,scottish wheat-soils showed a variation of from 4#jgd to 4#bb in the surface-soil1 while he found in their subsoil from 4#ae to 4#ib per cent4 ,boussingault's results are also very much higher4 ,the amount of nitrogen in a number of loams coming from widely different localities he examined contained from #fjjj to #cj1jjj lb4 per acre--the soil taken to a depth of #ag inches4#gd ,nature of the ,nitrogen in the ,soil4 ,when we compare the amount of nitrogen removed by different crops 7which1 even in the case of those most exhaustive of nitrogen1 does not often amount to more than #aej lb4 per acre71 with the amount contained in the soil1 the former amount seems very insignificant when compared to the latter4 ,such being the case1 it would seem at first sight that the addition of nitrogen in the form of manures is quite superfluous4 ,we must remember1 however1 that while the total amount of nitrogen is relatively large when compared to that removed by crops1 only a very small proportion is in a condition available to the plant4 ,this leads us to consider the different forms in which nitrogen is present in the soil1 and their respective quantities4 ,organic ,nitrogen in the ,soil4 ,nitrogen occurs in the soil as organic nitrogen1 nitric acid1 nitrous acid1 and ammonia4 ,by far the largest proportion is present in the first of these forms4 ,this is a wise provision1 for otherwise the soil would be apt to become very speedily impoverished in nitrogen2 for that present as nitrates it has scarcely any power to retain1 while that present as ammonia is soon converted into nitrates by the process of nitrification4 ,the organic nitrogen of the soil1 although we are apt to think of it as such1 is by no means of a homogeneous character1 or of equal value as a source of plant-food4 ,some of it1 it would seem from recent investigations1 is in a condition more susceptible of being converted into an available form than the rest4 ,thus in the process of nitrification1 a process which we shall consider at length immediately1 there seems to be generally a certain small proportion more ready to undergo this change than the rest2 so that when this small amount is used up nitrification proceeds more slowly4 ,in short1 although we as yet know very little of the nature of the organic nitrogen of soils1 we cannot doubt but that there is a constant series of changes in its composition taking place1 resulting in the gradual elaboration of more available forms1 until ultimately these are converted into ammonia and nitrates4 ,the great bulk of the organic nitrogen1 however1 in the soil must be regarded as in an inert condition1 and by no means available for the crop4 ,what the exact chemical form of this nitrogen is it is extremely difficult to say4 ,mulder was of the opinion that a considerable proportion was in the form of humate of ammonia4 ,this opinion1 as we shall have occasion to see immediately1 was based on false grounds4 ,it is highly probable that it may be in some form approximating to amide nitrogen4 ,its inert character is against the belief that it long remains as albuminoid nitrogen4 ,different ,character of ,surface and ,subsoil ,nitrogen4 ,a point of very considerable importance to notice is1 that the nitrogenous organic matter of the surface-soil is very different from that found in the subsoil4 ,this difference is shown by the variation in the ratio of nitrogen to carbon1 which points to the fact that1 just as we should naturally suppose1 the origin of the latter is very much more ancient than the origin of the former4 ,thus in the first #i inches of old pasture-soil at ,rothamsted1 the ratio was #a3ac2 while in the subsoil1 #c feet from the surface1 it was only #a3f4 ,in the surface-soil it thus approaches more nearly in composition ordinary vegetable matter4 ,nitrogen as ,ammonia in ,soils4 ,the second form in which nitrogen is present in soil is as ammonia4 ,a very considerable misapprehension has existed in the past as to the amount of nitrogen in this form in soils4 ,this mistake was due to the method adopted in estimating it1 which consisted in treating the soil with boiling caustic alkalies and counting as ammonia what was given off as such4 ,it is now known that certain forms of organic nitrogen--as1 for example1 amides--if treated in this way are slowly converted into ammonia4 ,statements1 therefore1 which are found in the older text-books1 representing the amount of ammonia in soils as at over a tenth per cent1 must be regarded as utterly unreliable4 ,indeed it is highly probable that ammonia only occurs in most soils in very minute traces4 ,from what we know of the process of nitrification1 we see how it is wellnigh impossible that ammonia should exist to any extent in the soil except under very exceptional circumstances4 ,amount of ,ammonia present in the ,soil4 ,in ordinary soils it probably does not amount to more than from 4#jjjb per cent to 4#jjjh per cent1 or an average of 4#jjjf per cent4#ge ,in rich soils1 or in garden-soils1 the amount may be considerably more4 ,thus ,boussingault found in a garden-soil 4#jjb per cent4 ,in peat and in peat-mould even a higher percentage has been found--viz414#jah for the former and 4#je for the latter4 ,nitrogen present as ,nitrates in the ,soil4 ,the third form of nitrogen in the soil is nitric acid4 ,it is more abundant in this form than as ammonia2 but still1 compared with the organic nitrogen1 its amount is trifling4 ,probably not more than #e per cent of the total nitrogen of a soil is ever present as nitrates4 ,the reason of this is twofold4 ,first1 as we have already remarked1 the soil has very little power to retain nitrogen in this form2 and secondly1 where the soil is covered with growing vegetation the nitrates are quickly assimilated by the plant as they are formed4 ,it is for this reason that we find the quantity of nitrogen as nitrates very much greater in fallow soils than in those covered with a crop4 ,position of ,nitric ,nitrogen in ,soil4 ,as we shall have occasion to see more fully in the following chapter on ,nitrification1 the formation of nitrates is chiefly limited to the surface-soil1 the largest proportion being formed within the first #i or #ab inches4 ,for this reason we find the largest quantity of nitrates in the surface-soil4 ,but inasmuch as they are easily washed into the lower layers of the soil after formation1 we often find a considerable proportion beyond the first #i inches4 ,the position of nitrates in the soil thus depends very considerably on the season of the year and the weather4 ,in dry weather1 where the evaporation of the soil-water takes place at a considerable rate1 the tendency will be to concentrate the nitrates in the superficial portion of the soil4 ,in wet weather1 on the other hand1 the tendency will be to wash the nitrates into the lower layers4 ,amount of ,nitrates in the ,soil4 ,the determination of the amount of nitrates in a soil is not of very great economic importance2 as this varies so much1 and depends on such a number of different conditions1 such as the season1 the condition of the land1 and prevailing weather4 ,a point of very much greater economic importance is the total amount formed in the year1 and the rate at which nitrification takes place4 ,these questions will be discussed elsewhere1 and therefore need not here be referred to4 ,some interesting analyses made at ,rothamsted1 however1 of the amount of nitrates in soils at different depths1 merit careful consideration4 ,nitrates in ,fallow ,soils4 ,in the ,appendix to the chapter on ,nitrification1#gf will be found a table containing the amounts of nitrates found in the first #bg inches of fallow soils4 ,the amounts vary from #cc4g lb4 to #ei4i lb4 per acre4 ,the analyses were made in ,september or ,october4 ,in four out of the six analyses1 it will be found that by far the largest proportion is found in the first #i inches4 ,in these cases the preceding summer had been dry1 and thus the nitrates had not been washed down to any depth4 ,in the other two cases the largest amount is found in the second #i inches of soil1 and a considerable amount is also found in the third #i inches4 ,nitrates in ,cropped ,soils4 ,in the case of cropped soils we find the amount of nitrates very much less4 ,a table containing an elaborate series of determinations of nitrates in cropped soils1 receiving1 however1 no manure1 and taken to a depth of #i feet1 will be found in the ,appendix4#gg ,the first #bg inches only contain some #e to #ad lb4 per acre1 and the most of that is found in the first #i inches4 ,this shows how speedily nitrates are assimilated by the growing crop4 ,an interesting point shown by these analyses is that nitrates almost entirely cease in cropped soils a certain depth down1 but that at a still lower depth they again occur in small quantities4 ,nitrates in manured ,wheat-soils4 ,lastly1 we give in the ,appendix#gh the amount of nitrates found in wheat and barley soils1 differently manured1 at ,rothamsted4 ,from a perusal of these tables1 it will be seen that the amount 7under various conditions of manuring7 of nitrates in the first #bg inches varies from #ba4b lb4 per acre to #eb4b lb4 for the wheat-soils1 and #bj4a to #dd4a lb4 per acre for the barley-soils4 ,,the ,,sources ,,of ,,soil-,,nitrogen4 ,we shall now consider the sources of soil-nitrogen1 the conditions which determine its increase1 and the amount of that increase1 as well as the sources of loss1 and the conditions which determine this loss4 ,that dissolved in ,rain4 ,the natural sources of the soil-nitrogen are several4 ,we have first of all the atmospheric nitrogen4 ,of this let us first consider that present as combined nitrogen4 ,this1 as we have already seen1 consists chiefly of nitrates1 nitrites1 and ammonia1 and reaches the soil dissolved in rain or in other meteoric forms of water1 such as snow1 hail1 fog1 hoar-frost1 c4 ,that absorbed by the ,soil from the ,air4 ,it is also absorbed by the soil from the air1 especially when the soil is in a damp condition1 as has been proved by ,schloesing's experiments1 already referred to4 ,the total amount which falls dissolved in the rain1 per acre per annum1 varies very considerably in different parts of the world1 but in any case only amounts yearly to a few pounds per acre4#gi ,that absorbed by the soil from the air may be probably very much more considerable4 ,schloesing in his experiments found that this latter might amount to #ch lb4 per acre per annum4 ,these results1 however1 were obtained under circumstances most favourable for absorption--viz41 with a damp soil and in the vicinity of ,paris1 where the air is presumably richer in combined nitrogen than it is in the country4 ,the nitrogen absorbed1 it may be mentioned1 was almost entirely in the form of ammonia4 ,it is to be noted that the nitrogen the soil obtains in this way from the combined nitrogen of the air is not all pure gain4 ,with regard to the nitrates and nitrites1 no doubt most of these are formed by electrical discharge1 although a small portion of them may be formed by the oxidation of ammonia by means of ozone and peroxide of hydrogen4 ,with regard to the ammonia and the combined nitrogen present in the organic particles in the air1 a not inconsiderable proportion is probably derived from the soil4 ,schloesing considers the chief source of the ammonia present in the air to be the tropical ocean2 but we must remember that the source of much of the nitrogen in the tropical ocean is1 after all1 the soil4 ,leaving aside for a moment the question of the availability of the free nitrogen of the air1 let us consider the other sources of soil-nitrogen4 ,accumulation of ,soil-nitrogen under ,natural ,conditions4 ,the chief source is of course the remains of vegetable and animal tissue4#hj ,plants are the great conservers of soil-nitrogen4 ,by assimilating such available forms of it as nitrates1 and converting them into organic nitrogen1 they prevent the loss of this most valuable of all soil constituents that would otherwise take place4 ,they also serve to collect the nitrogen from the lower soil-layers and concentrate it in the surface portion4 ,in a state of nature1 where the soil is constantly covered with vegetation1 the process going on1 therefore1 will be one of steady accumulation of nitrogen in the surface-soil4 ,to what extent this accumulation goes on1 and how far it is limited by the conditions of loss1 will be considered immediately4 ,that it may go on to a very great extent is amply proved by the existence of the so-called virgin soils of countries like ,america and ,australia4 ,there are cases1 also1 where the accumulation of nitrogen is practically unlimited1 although the result in such cases is not necessarily a fertile soil4 ,such cases are peat-bogs4 ,but let us pass on to the accumulation of soil-nitrogen under the ordinary conditions of husbandry4 ,accumulation of ,nitrogen in ,pastures4 ,the case which1 under the conditions of ordinary farming1 most resembles a state of nature1 is that of permanent pasture4 ,it will be best1 therefore1 to study first the conditions under which gain of nitrogen takes place in this case4 ,increase of ,nitrogen in the soil of ,pasture-land4 ,that there is a steady increase of nitrogen in the soil of land under pasture is a fact of universal experience4 ,the older a pasture is the richer is its soil in nitrogen4 ,the comparison of the analyses of the soil of arable land with the soil of pastures of different ages shows this in a striking way4#ha ,thus at ,rothamsted it was found that while the amount of nitrogen in an ordinary arable soil was 4#adj per cent1 that in pastures eight1 eighteen1 twenty-one1 and thirty years old was respectively 4#aea1 4#agd1 4#bjd1 and 4#bda per cent4 ,in the last two analyses we have a record of the actual gain in nitrogen made by the same pasture1 this being 4#jd per cent in nine years' time4 ,from these statistics it may be inferred that the surface-soil of a pasture may increase at the rate of #ej lb4 per acre per annum4 ,a point of great interest in connection with this subject is the fact that there seems to be a limit to the accumulation of nitrogen in pastures2 for it would seem that pastures centuries old are not any richer in nitrogen than those thirty to forty years old4 ,gain of ,nitrogen with ,leguminous ,crops4 ,another case where the gain of nitrogen to the surface-soil is very striking is in that of leguminous crops1 such as clover1 beans1 peas1 c4 ,this fact has been long recognised--especially with regard to clover--by farmers1 and has been largely instrumental in leading to the investigation of the free nitrogen question4 ,that a soil bearing a leguminous crop increases in nitrogen at a very striking rate is a problem that requires to be solved4 ,a partial explanation of the phenomenon is found in the extraordinary capacity such a crop as clover has1 by means of its multitudinous and ramifying roots1 for collecting nitrogen from the subsoil4 ,this1 however1 would only account for the increase in nitrogen to a certain extent4 ,there must be some other source1 and the only other source is the air4 ,that the free nitrogen of the air is1 after all1 available for the plant's needs1 is a supposition which has long seemed extremely probable1 and which1 within the last few years1 has been proved beyond doubt to be a fact in the case of leguminous plants4 ,the ,fixation of ,free ,nitrogen4 ,the method in which these plants are able to make use of the free nitrogen is still a point requiring much research4 ,so far as the question is at present investigated1 it would seem that the fixation is effected by means of micro-organisms present in tubercles or root excrescences found on the roots of leguminous plants4#hb ,not merely has this been placed beyond doubt1 but attempts have been made to isolate and study the bacteria effecting this fixation4 ,from ,nobbe's exceedingly interesting experiments1 recently carried out1 it would seem that the different kinds of leguminous plants have different bacteria4 ,thus the bacteria in the tubercle on the pea seems to be of a different order from the bacteria in the tubercles of the lupin1 and so on4 ,this discovery is of great importance1 it need scarcely be pointed out1 as it throws much light on the principles of the rotation of crops4 ,influence of ,manures in increasing ,soil-nitrogen4 ,it may be doubted1 however1 if under any other conditions there is a positive gain of soil-nitrogen4 ,in other cases the amount in the soil is only maintained under liberal manuring4 ,in connection with this point a very striking fact has been observed with regard to the effect of continuous large applications of farmyard manure4 ,it has been found at ,rothamsted that in such a case1 after a while1 the manure does not seem to increase the soil-nitrogen1 although where the nitrogen goes to remains a mystery4 ,in the case of the application of artificial manures1 there does not seem to be almost any appreciable gain to the soil-nitrogen4 ,the soil-nitrogen is only increased by means of the residue of crops4 ,in this way1 of course1 by increasing the amount of this crop-residue1 artificial manures may be said indirectly to increase the soil-nitrogen4#hc ,,sources ,,of ,,loss ,,of ,,nitrogen4 ,we now come to consider the sources of loss4 ,the chief source1 of course1 is that by drainage4 ,land under cultivation will suffer very much more from this source of loss than in a state of nature4 ,our modern system of husbandry1 involving as it does thorough drainage1 can scarcely fail to very considerably increase this source of loss4 ,loss of ,nitrates by ,drainage4 ,the form in which nitrogen is lost in this way is as nitrates4 ,it is a somewhat striking fact1 and one worthy of note1 that of the three important manurial ingredients--nitrogen1 phosphoric acid1 and potash1 the first of these1 in its final and most valuable form1 is alone incapable of being fixed by the soil1 and thus retained from loss by drainage4 ,as nitrates are constantly being formed in the soil1 the loss to its total nitrogen must be considerable4 ,it is due to the fact of the great solubility of nitrates1 as well as to the fact1 as already mentioned1 of the incapacity of the soil-particles to fix them4 ,to this one exception must be made4 ,according to ,knop1 small quantities of nitric acid are held in the insoluble condition in soils in the form of highly basic nitrates of iron and alumina4 ,the quantity1 however1 of these insoluble compounds probably amounts to a very minute trace indeed4 ,permanent ,pasture and ,catch-cropping prevents ,loss4 ,the amount of loss varies1 and will depend on a number of different circumstances--thus the nature of the soil1 climate1 and season of the year will all influence its quantity4 ,the way in which the soil is cultivated is also another important factor4 ,where it is constantly covered with vegetation1 as in the case of permanent pasture1 the loss will be at a minimum4 ,under such conditions1 plant-roots are always there ready to fix1 in the insoluble organic form1 the soluble nitrates as they are formed4 ,a consideration of this fact forms one of the strongest arguments in favour of the practice of what is known as catch-cropping4 ,the practice consists in sowing some quickly-growing green crop--e4g41 mustard1 vetches1 c4--so as to occupy the soil immediately after harvest1 and subsequently to plough it in4 ,the nitrates1 which it is known are most abundantly formed towards the end of summer1#hd and which are allowed to accumulate in the soil from the period at which the active growth of1 and consequently assimilation of nitrates by1 the cereal crop have ceased1 are thus fixed in the organic matter of the plant1 and removed from danger of loss by drainage incidental to autumn rains4 ,other ,conditions diminishing ,loss of ,nitrates4 ,the nature of the soil is another important condition regulating this loss4 ,some soils are very much opener and more porous than others2 in such soils1 of course1 the loss by drainage will be greatest4 ,we are apt at first sight1 however1 knowing the great solubility of nitrates1 to overrate this source of loss4 ,we have to remember that while nitrates are constantly being washed down to the lower layers of the soil1 there is likewise an upward compensating movement of the soil-water constantly taking place4 ,this is due to the evaporation of water from the surface of the soil1 which induces an upward capillary movement of water from its lower to its higher layers4#he ,this upward movement of water is very much increased1 in the case of soil covered with vegetation1 by the transpiration of the plants4 ,the climate and the season of the year will affect the extent of this upward movement4 ,where there is a heavy rainfall it will be very much less than in dry climates4 ,after a long period of drought the nitrates will be found to be concentrated in the top few inches of the soil2 and in hot climates this sometimes takes place to such an extent that the surface of the soil has been actually covered with a saline crust1 caused by the rapid evaporation of soil-water under the influence of a burning tropical sun4 ,from this point of view it will be seen how very much less powerful a single shower of rain is--even although at the time it is heavy--in causing loss of nitrates by drainage1 than a continuance of wet weather4 ,in the former case1 where the showers are separated by an interval of dry weather1 the nitrates washed down into the lower layers of the soil are slowly brought up again by the capillary action caused by evaporation4 ,amount of ,loss by ,drainage4 ,what the actual amount of loss is which takes place in this way it is wellnigh impossible to say4 ,what it amounts to under certain definite circumstances has been discovered by actual experiment at ,rothamsted4 ,taking the circumstances most favourable to extreme loss--viz41 unmanured fallow land--the highest amount registered at ,rothamsted for a year is #ed4b lb4 per acre from soil #bj inches deep1 while the smallest amount is #bj4i lb4 ,in the former case1 the drainage-water was equivalent to #ba4ff inches1 while in the latter1 to #h4if inches4 ,the average for thirteen years on unmanured fallow soil has been #cg4c lb4 7for #bj inches71 #cb4f lb4 7for #dj inches71 #ce4f lb4 7for #fj inches74 ,the point of especial interest in this connection is that an annual loss of nitrogen1 equal to over #b cwt4 of nitrate of soda1 may take place from a comparatively poor arable soil lying fallow4 ,the loss on cropped soils is of course very much less--in short1 should amount to very little--especially in permanent pasture1 where it is reduced to a minimum4 ,taking an average1 ,mr ,warington is of opinion that the loss in ,england may be put at #h lb4 per annum per acre4#hf ,loss in ,form of ,free ,nitrogen4 ,the other chief natural source of loss of nitrogen is due to its escape from the soil in its free state4 ,this source of loss is very much less important than that by drainage1 and probably amounts to very little4 ,that1 however1 it takes place is beyond a doubt2 and that it may--as we shall see by-and-by--under certain circumstances amount to something very considerable is also proved4 ,where large quantities of nitrogenous organic matter decay1 and where1 consequently1 the supply of atmospheric oxygen is insufficient to effect complete oxidation1 free nitrogen may be evolved in considerable quantities4 ,similarly1 it may be evolved in the case of vegetable matter decaying under water4 ,in soils rich in organic matter the reduction of even nitrates may take place1 accompanied with the evolution of free nitrogen1 which is thus lost4 ,total ,amount of ,loss of ,nitrogen4 ,what the rate of total loss of nitrogen is from these different sources does not admit of easy calculation4 ,sir ,john ,lawes1 in dealing with the question of soil-fertility1 estimated some years ago1 by comparing the soil of old pasture at ,rothamsted with that which had been under arable culture for #bej years1 that during that period some #cjjj lb4 of nitrogen per acre had disappeared from the arable land4 ,examples of decrease of nitrogen in ,rothamsted soils1 under various conditions of culture1 will be found in the ,appendix4#hg ,loss of ,nitrogen by ,retrogression4 ,a source of loss of nitrogen may be here mentioned which has to do with diminution of amount of available nitrogen1 rather than absolute loss of nitrogen to the soil1 and which we may term loss by retrogression4 ,nitrogen in an available form1 such as nitrates1 has been found to be converted into a less available form4 ,this retrogression may be effected1 as in the case of nitrates1 by reduction--i4e41 by removal of the oxygen in combination with the nitrogen1 which in many cases may be set free1 and thus partially although not necessarily entirely lost4 ,such reduction is due to the action of bacteria of the denitrifying order4#hh ,or1 on the other hand1 nitrogen may be converted into some kind of insoluble form which seems to resist decomposition and lies in an inert condition in the soil utterly unavailable for the plants' needs4 ,a striking example of this retrogression of nitrogen seems to be afforded in the case of farmyard manure4 ,it has been found in the ,rothamsted experiments1 as has been pointed out in the preceding pages1 that when farmyard manure is applied1 year after year1 to the same land in large quantities1 a very considerable percentage of its nitrogen does not 7i4e41 within a reasonable number of years7 become available for the crop's uses4 ,what1 indeed1 becomes of the nitrogen is a mystery2 but it is highly probable that some such kind of retrogression as that above referred to1 whereby the nitrogen is converted into some inert organic form1 takes place4 ,artificial ,sources of ,loss of ,nitrogen4 ,so far1 the sources of loss of nitrogen considered have been what we may term natural sources4 ,by this is meant that the loss of nitrogen from the above sources takes place in a state of nature1 and not merely under conditions of cultivation4 ,no doubt the loss due to drainage is very much greater under arable farming than would be the case where artificial drainage does not obtain2 still1 under any conditions1 this loss must be reckoned with4 ,on the other hand1 by artificial sources of loss are meant those entirely dependent on our modern system of agriculture and our modern system of sewage disposal1 whereby the nitrogen contained in that portion of the produce of the farm which goes to supply our food is not returned to the soil1 but is totally lost4 ,amount of ,nitrogen removed in ,crops4 ,the modern tendency towards centralisation in large towns has rendered this loss--despite all that has been said to the contrary--a necessity4 ,it is extremely difficult1 however1 to form any estimate of its amount4 ,we know1 of course1 the amount of nitrogen removed from the soil by different crops4 ,we cannot1 however1 estimate how much of this may find its way back again to the soil4 ,the amount of nitrogen contained in the different crops will be fully dealt with in the chapter on the manuring of different crops4 ,it may be1 however1 not without interest to give here some approximate indication of the amount of this loss1 in order to render the view of the subject as comprehensive as possible4 ,recent agricultural returns for ,great ,britain give the total produce of wheat at over #gf million bushels1 that of barley at over #fi million1 and that of oats at over #aej million4 ,calculating the amount of nitrogen1 these quantities of wheat1 barley1 and oats respectively and collectively contain1 and calculating also how much sulphate of ammonia and nitrate of soda these amounts of nitrogen represent1 the following are the results3-- ,nitrogen4 ,sulphate of ,nitrate of ,ammonia4 ,soda4 ,bushels4 ,tons4 ,tons4 ,tons4 ,wheat #gf1bbd1idj #cg1dcb #agf1dfe #bbg1bff ,barley #fi1idh1bff #bg1cbd #abh1hac #afe1hif ,oats #aej1ghi1daf #ef1hce #bfg1icf #cde1jfh ----------- ------- ------- ------- ,total #bif1ifb1fbb #aba1eia #egc1bad #gch1bcj ,of course these figures1 so far as the amounts of nitrogen are concerned1 can only be regarded as approximate1 as it is only possible in such calculations to obtain approximate results4 ,accepting these calculations as merely approximate1 they are1 nevertheless1 of the highest interest and importance4 ,it is of great importance to understand that in the annual produce of our three common cereal crops--supposing them to be all consumed off the farm--there is removed from the soil a quantity of nitrogen equal to that contained in over half a million tons of sulphate of ammonia1 and three quarters of a million tons of nitrate of soda4 ,as has already been remarked1 it is impossible to estimate exactly what proportion of this total nitrogen finds its way back to the soil4 ,in the case of wheat1 it may be pointed out that the portion which is used as a feeding-stuff--viz41 bran--is very much richer in nitrogen than the flour4 ,while1 then1 we are unable to estimate with any exactitude this source of loss of nitrogen1 it cannot for a moment be doubted that it is enormous1 from what has been already stated4 ,we must remember that the portion of the crop richest in nitrogen is that which is generally removed--the straw which is grown in producing a bushel of wheat1 barley1 or oats1 containing less than half the amount of nitrogen contained by a bushel of the grain itself4 ,losses of ,nitrogen incurred on the ,farm4 ,in addition to the loss due to removal of crops from the farm1 there are one or two other sources of loss which it may be well to briefly refer to4 ,loss in ,treatment of ,farmyard ,manure4 ,there can be little doubt that in the past a very considerable source of loss was the improper treatment of farmyard manure4 ,the way in which this loss may take place will be fully considered in the chapter on farmyard manure4 ,suffice it to say here1 that this may take place by volatilisation of the nitrogen as carbonate of ammonia1 caused by carelessness in allowing the temperature of the manure-heap to rise too high2 or by drainage of the soluble nitrogen compounds1 caused by allowing the rich black liquor of the manure-heap to be washed away1 and not properly conserved4 ,nitrogen removed in ,milk4 ,another source of loss which is apt to be overlooked is the amount of nitrogen removed in milk4 ,professor ,storer has calculated that in the case of a cow giving #bjjj quarts1 or #dcjj lb41 of milk in a year1 and the milk being all sold as such1 there would be carried away from the farm #bb lb4 of nitrogen4#hi ,economics of the ,nitrogen question4 ,and here1 before concluding our survey of the different sources of loss of nitrogen1 it may be well to regard for a moment the subject from a somewhat wider standpoint than that from which we have been considering it4 ,the total supply of nitrogen in a combined form is limited4 ,as we have pointed out1 it may be regarded as the element on which1 more than any other1 life1 animal as well as vegetable1 depends4 ,to animal life it is alone available in combined form2 to vegetable life it is chiefly also only available in combined form4 ,in the air we have an unlimited quantity of nitrogen1 but it is almost entirely in an uncombined form1 and therefore largely unavailable4 ,the conversion of nitrogen from the free state to a combined form is a process which takes place only very slowly4 ,any source which diminishes the sum-total of our already all too limited supply of combined nitrogen must be regarded as worthy of most serious consideration4 ,the question1 therefore1 of the artificial waste of nitrogen daily taking place around us1 is one which ought to possess for economists a very great interest indeed4 ,this waste has1 of late years1 enormously increased1 and would seem to threaten us at no very distant date with a nitrogen famine4 ,it is incidental to the use of certain nitrogenous substances in the manufacture of various articles1 and to our present system of sewage disposal4 ,loss of ,nitrogen-compounds in the ,arts4 ,the articles referred to are such as explosives1 starch1 textile substances1 malt liquors1 c4 ,the question is strikingly dealt with in an able paper on ,the ,economy of ,nitrogen in the ',quarterly ,journal of ,science4'#ij ,loss due to ,use of ,gunpowder4 ,the explosives--more particularly gunpowder--are the most important of these articles4 ,gunpowder contains #ge per cent of saltpetre1 which in its turn contains about #aj per cent of nitrogen4 ,when gunpowder explodes1 practically the whole of this nitrogen is converted into free nitrogen4 ,the loss is thus in a sense irreparable4 ,in the paper above1 referred to1 our total annual exports of this substance are estimated at #ai1jjj1jjj lb42 while the total annual production of the world is estimated at not less than #ajj1jjj1jjj lb4 ,the annual loss of nitrogen due to this source alone would amount to about #aj1jjj1jjj lb4#ia ,similarly1 loss of nitrogen1 although to a less extent1 is caused by the use of other explosives1 as well as in the manufacture of the other articles above mentioned4 ,loss due to ,sewage ,disposal4 ,the loss due to our present system of sewage disposal has been already taken into account in dealing with the loss due to removal of crops4 ,it may be well1 however1 to treat it from the sewage aspect4 ,taking the amount of nitrogen in the excreta of every individual as1 on an average1 half an ounce1 the annual amount voided in the excreta of the total population of the ,british ,isles would amount to #cfe1jjj1jjj lb4#ib--of this1 the amount in the ,london sewage alone being #ia1jjj1jjj lb4#ic ,by the water system1 which is almost universally adopted in this country1 the above quantity of nitrogen is entirely lost to the soil4 ,a small portion of it1 it may be argued1 is eventually recovered in sea weed and fish1 which may be used for manure4 ,this1 however1 is to argue too much sub specie aeternitatis4 ,not all the nitrogen originally present in the excreta finds its way into the sea2 for it is highly probable that a considerable quantity escapes in the process of the decomposition of the sewage as free nitrogen4 ,from the above statement of the sources of loss and gain of nitrogen taking place in the soil1 it may be pretty safe to conclude that while in a state of nature the gain balances the loss1 if indeed it does not do more1 under conditions of arable farming such is very far from being the case2 and that if fertility of the land is to be maintained1 recourse to nitrogenous manures must be had1--in short1 that the application of artificial nitrogenous manures is a necessary condition of modern husbandry4 ,our ,artificial ,nitrogen ,supply4 ,before concluding this chapter1 it may be interesting to enumerate very briefly the chief sources of our artificial nitrogen supply4 ,nitrate of ,soda and ,sulphate of ,ammonia4 ,the most important artificial nitrogenous manures in use at present are nitrate of soda and sulphate of ammonia4 ,of the former1 the annual exportation from ,chili is close on one million tons1 of which quantity about #abj1jjj tons is imported into the ,united ,kingdom4 ,of sulphate of ammonia1 on the other hand1 the total production in this country is about #acj1jjj tons per annum1#id the greater proportion of which is exported1 leaving only from #cj1jjj to #dj1jjj tons for consumption4 ,nitrate of soda1 it must be remembered1 is not entirely used for manurial purposes1 a small proportion of the above imports being used for chemical manufacturing purposes4 ,peruvian ,guano4 ,peruvian guano is another important nitrogenous manure very much less abundant now than formerly1 as the different guano-beds have become nearly exhausted4 ,while the imports of this important manure into the ,united ,kingdom amounted in #ahgj to nearly #bej1jjj tons1 at present not more than #aa1jjj tons are being imported4 ,bones4 ,a further source of nitrogen is bones1 which1 of course1 are chiefly valuable as a phosphatic manure1 but which contain also some #c to #d per cent of nitrogen4 ,of this valuable manure we import at present about #cj1jjj tons1 while about #fj1jjj tons are collected in this country1 bringing up our total consumption to #ajj1jjj tons4 ,other ,nitrogenous ,manures4 ,the above mentioned are the most important of nitrogenous manures2 there are1 however1 a number of other nitrogenous manures used in this country in very much smaller quantities4 ,as most of these substances are made in this country1 it is very difficult to estimate the amount of their annual production with exactness4 ,these substances are as follows3 fish-guano1 meat-meal guano1 dried blood1 shoddy1 scutch1 horns and hoofs1 hair1 bristles1 feathers1 leather-scrap1 c4 ,of fish-guano1 the total consumption per annum may be put down at about #hjjj tons1 of which a fourth is imported into this country1 the remaining #fjjj tons being manufactured at home4 ,of meat-meal guano1 dried blood1 hoof-guano1 c41 about #bejj tons are annually imported1 the home production bringing up the total amount to some #aj1jjj tons4 ,of shoddy1 some #ab1jjj tons are manufactured in this country2 while scutch--the name given to a manure manufactured from the waste products incidental to the manufacture of glue and the dressing of skins--is produced only to the extent of a few thousand tons annually4 ,it is a fact worthy of notice1 that while the use of phosphatic manures has increased very considerably of late years1 the same cannot be said of nitrogen4 ,according to ,mr ,hermann ,voss1 some #cd1jjjie tons of nitrogen were used in the form of artificial manures in #ahgc1 while now only about #bh1jjj tons are used--i4e41 some #fjjj tons less4 ,oil-seeds and ,oilcakes4 ,there still remains a very important source of nitrogen which has not yet been mentioned1 in the shape of oil-seeds and oilcakes1 used for feeding purposes4 ,oilcakes are both manufactured in this country and imported in large quantities4 ,recent ,agricultural ,returns show the total imports of oilcakes at #bef1bif tons2 that of linseed at #cgj1jjj tons2 that of rape-seed at #hj1jjj tons2 and that of cotton-seed at #bhi1dac tons4 ,other imported ,sources of ,nitrogen4 ,we have further1 in considering this question1 to take into account the large amount of maize1 peas1 beans1 wheat1 and oats which are imported into this country1 a certain quantity of which is used as cattle-food1 and will therefore go to enrich their manure4 ,also the imported straw used for purposes of litter must not be forgotten4 ,in #ahhg this amounted to #eb1cic tons4 ,conclusion4 ,in conclusion1 it may be asked how far are the artificial sources of nitrogen able to make good the loss8 ,in the opinion of such a reliable authority as ,sir ,john ,lawes1 they do not4 ,there are some soils which depend almost entirely upon imported fertility1 and could not be cultivated without it4 ,upon some of them it is possible that the imports of nitrogen are in excess of the exports4 ,taking the agricultural acreage as a whole1 however1 he is of opinion that there is a decided loss of nitrogen1 which he estimates at from #ae lb4 to #bj lb4 per acre per annum4#if ,,footnotes3 #fc ,the total amount of nitrogen in the air has been estimated approximately at four million billion tons4 #fd ,see ,introductory ,chapter1 pp4 #dj to #de4 #fe ,although ammonia is more abundant than nitrates and nitrites1 it only amounts to a few parts per million of air4 ,according to ,muentz1 the air at great heights contains more ammonia than in its lower strata4 ,the opposite1 however1 is the case with regard to nitrates1 which are only found in air near the surface of the earth4 ,see p4 #di4 #ff ,nitric acid may also be formed by the oxidation of ammonia by ozone1 or peroxide of hydrogen4 #fg ,according to ,schloesing1 the chief source of the ammonia present in the air is the tropical ocean1 which yields gradually to the atmosphere1 under the action of the powerful evaporation constantly going on1 a large amount of nitrogen in this form4 ,the sources of the nitrogen of the ocean are the nitrates which it receives from the drainage of land1 animal and vegetable matter1 sewage1 c4 #fh ,see ,appendix1 ,note ,i41 p4 #aee4 #fi ,to illustrate this point1 it may be mentioned that on the least windy of days1 when the wind is only moving at the rate of two miles an hour--and this1 it may he added1 is so slow as to be scarcely noticeable--the air in a space of #bj feet is changed over five hundred times in an hour4 ,the combined nitrogen thus absorbed is probably entirely in the form of ammonia4 ,it would seem so at any rate1 from some experiments by ,schloesing4 ,see p4 #acb4 #gj ,no vegetable or animal cell exists which does not contain nitrogen4 #ga ,this is less on the whole than what has been found in subsoils by ,continental investigators4 ,thus1 for example1 ,a4 ,mueller found the average of a number of analyses of subsoils to be 4#ae per cent41 and the late ,dr ,anderson found the nitrogen in the subsoil of different ,scottish wheat-soils to run from 4#ae per cent to 4#ig per cent4 #gb ,see ,appendix1 ,note ,,ii41 p4 #aef4 #gc ,under prolonged kitchen-garden culture the subsoil becomes enriched with nitrogenous matter to a far more considerable depth2 this has been shown by the analyses of the soil of the old kitchen-garden at ,rothamsted4 ,this is doubtless due to the practice of deep trenching employed by gardeners4--,r4 ,warington1 ',lectures on ,rothamsted ,experiments4' ,u4,s4,a4 ,bulletin1 p4 #bd4 #gd ,the comparatively insignificant effect the addition of various nitrogenous manures have in increasing the total soil-nitrogen is strikingly illustrated in the tables given in the ,appendix1 ,note ,,iv41 p4 #aeg4 #ge ,see ,storer's ,agric4 ,chem41 vol4 i4 p4 #ceg4 #gf ,see ,chapter ,,iv41 ,appendix1 ,note ,,vii41 p4 #aih4 #gg ,see ,appendix1 ,note ,,iii41 p4 #aeg4 #gh ,see ,appendix1 ,note ,,iv41 p4 #aeg4 #gi ,see ,appendix1 ,note ,i41 p4 #aee4 #hj ,the original source of the nitrogen in the soil must have been the nitrogen in the air4 ,when plants first begin to grow on a purely mineral soil1 they must obtain nitrogen from some source4 ,the small traces washed down in the rain will supply sufficient nitrogen to enable a scanty growth of the lower forms of vegetable life2 whereas these by their decay furnish their successors with a more abundant source1 which rapidly increases1 until we have a fair percentage of humus accumulated4 #ha ,see ,appendix1 ,note ,v41 p4 #aeh4 #hb ,see ,historical ,introduction1 pp4 #dj-de4 #hc ,the evidence demonstrating this is to be found in the fact that the amount of carbon found in different soils rises or falls in proportion to the nitrogen4 ,see p4 #abf4 #hd ,see ,chapter ,,iv4 on ,nitrification4 #he ,diffusion as well as capillary attraction is a means of bringing nitrates again to the surface-soil after rain4 #hf ,see ,appendix1 ,note ,,vi41 p4 #aeh1 and ,note ,,viii41 p4 #afj2 also p4 #aed4 #hg ,see ,appendix1 ,note ,,vii41 p4 #aei4 #hh ,see following ,chapter on ,nitrification1 p4 #agh4 #hi ,according to the ,agricultural ,returns for #ahhh1 the number of cows in milk in ,great ,britain amounted to #b1dej1ddd4 ,if we multiply this number by #bb the result is #ed1jjj1jjj lb41 or in tons #bd1ajg4 ,this quantity represents #aed1jfg tons of ordinary commercial nitrate of soda4 #ij ,for #ahgh 7p4 #adf et seq47 ,the reader interested in the subject is referred to the paper itself4 #ia ,in tons #ddfd1 and represents #bh1ecj tons of nitrate of soda4 #ib ,this in tons #afb1idf1 which represents #a1jda1chd tons of nitrate of soda4 #ic ,this in tons #dj1fbe1 which represents #bei1fcc tons of nitrate of soda4 ,see paper in ',journal of ,science' already referred to4 #id ,europe's total production may be stated at #bjj1jjj tons4 #ie #aj1ejj tons of which were as guano4 #if ,mr ,warington estimates this at about #h lb4 ,see p4 #ada4 ,,appendix ,,to ,,chapter ,,iii4 ,,note ,i4 7p4 #aai74 ,,determinations ,,of ,,the ,,quantity ,,of ,,nitrogen ,,supplied ,,by ,,rain1 ,,as ,,ammonia ,,and ,,nitric ,,acid1 ,,to ,,an ,,acre ,,of ,,land1 ,,during ,,one ,,year4 7,from ,dr ,fream's ',soils and their ,properties1' p4 #fb47 ---------------------------------------- ------------------------------- ,nitrogen per million1 as ,total ---------------,nitrogen ,year4 ,rainfall4 per ,ammonia4 ,nitric acre4 ,acid4 ---------------------------------------- ------------------------------ lb4 ,kuschen #ahfd-fe #aa4he #j4ed #j4af #a4hf #ahfe-ff #ag4gj #j4dd #j4af #b4ej ,insterburg #ahfd-fe #bg4ee #j4ee #j4cj #e4di #ahfe-ff #bc4gi #j4gf #j4di #f4ha ,dahme #ahfe #ag4ji #a4db #j4cj #f4ff ,regenwalde #ahfd-fe #bc4dh #b4jc #j4hj #ae4ji #ahfe-ff #ai4ca #a4hh #j4dh #aj4ch #ahff-fg #be4cg #b4bh #j4ef #af4dd ,ida-,marienhuette1 mean of six years #ahfe-gj #bb4fe #i4ib ,proskau #ahfd-fe #ag4ha #c4ba #a4gc #bj4ia ,florence #ahgj #cf4ee #a4ag #j4dd #ac4cf #ahga #db4dh #j4ha #j4bb #i4hi #ahgb #ej4hb #j4hb #j4bf #ab4ea ,vallombrosa #ahgb #gi4hc #j4db #j4ae #aj4ch ,montsouris1 ,paris #ahgg-gh #bc4fb #a4ia #j4bd #aa4ed #ahgh-gi #be4gi #a4bj #j4gj #aa4af #ahgi-hj #ae4gj #a4cf #a4fj #aj4eb -------------------------------- ,mean of #bb years #bg4fc #aj4bc ---------------------------------------- ------------------------------ ,,note ,,ii4 7p4 #abb74 ,,nitrogen ,,in ,,soils ,,at ,,various ,,depths4 7#a7 ,rothamsted ,soils4 ---------------------------------------- -------------------------------- ,depth4 ,arable soil4 ,old pasture soil4 ---------------------------------------- ------------------------------ per cent4 lb4 per acre4 per cent4 lb4 per acre4 #ast #i inches #j4abj #c1jae #j4bde #e1cea #b;d #i #j4jfh #a1fbi #j4jhb #b1cac #c;d #i #j4jei #a1dfa #j4jec #a1ehj #dth #i #j4jea #a1bbh #j4jdf #a1dab #eth #i #j4jde #a1jij #j4jdb #a1cja #fth #i #j4jdd #a1aca #j4jci #a1ahf ----- ----- ----- ----- ,total1 #ed inches - #i1eed - #ac1adc ---------------------------------------- ------------ #gth #i inches #j4jdb #a1jdi - - #hth #i #j4jda #a1jie - - #ith #i #j4jdd #a1agc - - #ajth #i #j4jdc #a1jgf - - #aath #i #j4jdc #a1aab - - #abth #i #j4jde #a1aih - - ----- ------ ----- ----- ,total1 #i feet #af1beg ---------------------------------------- ------------------------------ 7#b7 ,manitoba ,soils4 ---------------------------------------- -------------- ,depth4 ,brandon4 ,niverville4 ,winnipeg4 ,selkirk4 ---------------------------------------- -------------- per cent4 per cent4 per cent4 per cent4 #ast foot #j4ahg #j4bfa #j4dbh #j4fah #b;d #j4aji #j4afi #j4cbg #j4bfd #c;d #j4jgb #j4jfi #j4aeh #j4jgf #dth #j4jai #j4jch #j4ajg #j4jdb ---------------------------------------- -------------- ,,note ,,iii4 7p4 #acj74 ,,nitrogen ,,as ,,nitrates ,,in ,,cropped ,,soils ,,receiving ,,no ,,nitrogenous ,,manure1 ,,in ,,lb4 ,,per ,,acre 7,rothamsted ,soils74 ---------------------------------------- ------------------------ ,wheat4 --------------- ,bokhara ,white ,after ,after clover1 ,vetches1 ,lucern1 clover1 ,depth4 fallow1clover1 #ahhb4 #ahhc4 #ahhe4 #ahhe4 #ahhc4 #ahhc4 ---------------------------------------- ----------------------- lb4 lb4 lb4 lb4 lb4 lb4 #ast #i inches #c4d #f4a #c4d #aj4b #h4i #aa4e #b;d #i #c4a #d4d #a4j #b4g #a4a #a4d #c;d #i #j4h #a4f #j4f #a4a #j4h #j4i #dth #i #a4j #a4c #a4j #a4e #j4h #a4i #eth #i #j4h #a4e #j4h #b4e #a4j #g4a #fth #i #j4f #j4h #a4g #d4d #j4i #aa4c #gth #i #j4h #b4b #d4e #j4f #ac4a #hth #i #j4i #a4g #d4i #j4h #ab4f #ith #i #j4g #b4d #d4h #j4g #aa4b #ajth #i #b4j #b4a #e4a #j4f #aj4g #aath #i #a4e #b4a #f4d #j4d #aa4a #abth #i #c4h #b4h #f4e #j4d #aj4j ---------------------------------------- ----------------------- ,,note ,,iv4 7p4 #abd and p4 #aca74 ,,nitrogen ,,as ,,nitrates ,,in ,,wheat-,,soils ,,variously ,,manured1 ,,october #ahha1 ,,in ,,lb4 ,,per ,,acre 7,rothamsted ,soils74 ---------------------------------------- ------------------------------- ,excess over ,plot ,manuring4 #ast #i #bnd #i #crd #i ,total #bgplots inchesinchesinchesinches #c and #d ---------------------------------------- ------------------------------- lb4 lb4 lb4 lb4 lb4 #c ,no manure1 #ch years #i4g #e4c #b4h #ag4h #d #cj #i4b #d4j #a4h #ae4j #af;a #ag #aj4f #e4j #b4c #ag4i #a4e #e;a ,ash constituents1 #cj years #ab4f #g4a #d4f #bd4c #g4i #ag;a #a year #aj4c #g4e #c4d #ba4b #d4h #f;a and ammonium salts1 #bjj lb4 #af4e #g4e #d4g #bh4g #ab4c #g;a #djj #bb4h #aa4c #e4g #ci4h #bc4d #h;a #fjj #ba4a #ac4i #g4h #db4h #bf4d #i;a ,ash and sodium nitrate1 #eej #ai4g #aj4j #h4b #cg4i #ba4e #i;b ,sodium nitrate1 #af4c #bj4a #ag4g #ed4a #cg4g #aj;a ,ammonium salts1 #djj #ad4b #aa4i #g4c #cc4d #ag4j #aa;a ,superphosphate and ammonium salts1 #djj lb4 #ag4i #i4c #c4f #cj4h #ad4d #ai ,rape-cake1 #agjj lb4 #ad4a #ac4j #g4a #cd4b #ag4h #b ,farmyard manure1 #ad tons--#ch years #cj4j #ae4d #f4h #eb4b #ce4h ---------------------------------------- ------------------------------- ,,nitrogen ,,as ,,nitrates ,,in ,,barley-,,soils ,,variously ,,manured1 ,,march #ahib1 ,,in ,,lb4 ,,per ,,acre 7,rothamsted ,soils74 ---------------------------------------- --------------------------- ,total ,excess #ast #i #b;d #i #c;d #i #bg over ,plot4 ,manuring4 inches4inches4inches4inches4plot #aj4 ---------------------------------------- --------------------------- lb4 lb4 lb4 lb4 lb4 #aj ,no manure #e4i #d4g #e4a #ae4g - #bj-dj ,ash constituents 7mean7 #f4g #g4j #f4d #bj4a #d4d #a ,a ,ammonium salts1 #bjj lb4 #f4a #h4c #g4j #ba4d #e4g #b;,a-#d;,a ,ammonium and ash constituents 7mean7 #g4g #g4h #g4f #bc4a #g4d #a ,,aa ,sodium nitrate1 #bge lb4 #i4g #f4h #i4j #be4e #i4h #b;,,aa-#d;,,aa,sodium nitrate and ash constituents 7mean7 #h4c #g4d #g4e #bc4b #g4e #a;,c ,rape-cake1 #ajjj lb4 #aj4f #ac4g #g4i #cb4b #af4e #b;,c-#d;,c ,rape-cake and ash constituents 7mean7 #h4h #aa4i #h4g #bi4d #ac4g #g-a ,no manure1 #aj years-- formerly dung #ad4h #aa4h #aj4i #cg4e #ba4h #g-b ,farmyard manure1 #ad tons #ah4f #ad4f #aj4i #dd4a #bh4d ---------------------------------------- -------------------------- ,,note ,v4 7p4 #acd74 ,,examples ,,of ,,increase ,,of ,,nitrogen ,,in ,,rothamsted ,,soils ,,laid ,,down ,,in ,,pasture4 ---------------------------------------- ----- ,age of ,nitrogen in pasture4 #ast #i inches4 ---------------------------------------- ----- ,years4 ,per cent4 ,arable land - #j4adj ,barn-field pasture #h #j4aea ,apple-tree pasture #ah #j4agd ,dr ,gilbert's meadow #ba #j4bjd ,dr ,gilbert's meadow #cj #j4bda ---------------------------------------- ----- ,,note ,,vi4 7p4 #ada74 ,in connection with the loss by drainage of nitrogen in the form of nitrates1 it may be mentioned that the water of many of the famous rivers contains large quantities of nitrates4 ,thus the water of the ,seine has been found to contain fifteen parts of nitrates per million of water1 and the ,rhine eight parts per million4 ,some idea of what this amounts to per annum may be obtained by the statement that the ,rhine discharges daily #bbj tons of saltpetre into the ocean1 the river ,seine #bgj1 and the ,nile #aajj tons4--7,storer's ,agric4 ,chem41 vol4 i4 p4 #cah47 ,,note ,,vii4 7p4 #adb74 ,,examples ,,of ,,decrease ,,of ,,nitrogen ,,in ,,rothamsted ,,soils4 ---------------------------------------- -------------- ,nitrogen in #ast #i inches4 ---------------------------------------- -------------- ,per cent4 ,old pasture #j4bej ,arable land in ordinary culture #j4adj ,wheat unmanured1 #ch years #j4aje ,wheat and fallow unmanured1 #ca years #j4jif ,barley unmanured1 #cj years #j4jic ,turnips unmanured1 #be years #j4jhe ---------------------------------------- -------------- ,,manuring1 ,,produce ,,of ,,wheat1 ,,and ,,alteration ,,in ,,the ,,composition ,,of ,,the ,,soil ,,in ,,broadbalk ,,field1 ,,rothamsted1 ,,from #ahfe ,,to #ahha4 ---------------------------------------- ------------------------------------- ,average ,nitrogen per acre produce in #ast #i inches ,plot4 ,manures per acre1 per acre4 of soil4 annually applied1 ----------------------------------- #af years1 #ahfe-ha4 ,gain or ,dressed ,total #ahfe4 #ahha4 loss in grain4 produce4 #af years4 ---------------------------------------- ---------------------------------- bush4 lb4 lb4 lb4 lb4 #c ,unmanured #aa-g_/h #agae #bejg #bdjd -#ajc #e;a,mixed mineral manure #ab-c_/d #aifc #begd #bcbh -#bdf #aj;a,ammonium salts1 #djj lb4 #ag-g_/h #bhha #bedh #bdga -#gg #aaa;,ammonium salts1 with superphosphate #bc-a_/d #chef #bfic #bfgf -#ag #g;a,ammonium salts1 with mixed mineral manure #bh #diic #bhbi #bijh #gi #i;a,nitrate of soda1 #eej lb41 and mixed mineral manure #cf #fidi #bhcd #bhhc #di #af;a,unmanured99 #ac-a_/b #baid #bijg #beeg -#cej #b ,farmyard manure1 #ad tons #ca-a_/b #ecef #dcbi #dejb #agc ---------------------------------------- ---------------------------------- 99 ,during #aheb-fd received annually ammonium salts1 #hjj lb41 with mixed mineral manure1 and yielded an average product of #ci-a_/b bushels of grain and #df-e_/h cwt4 of straw4 ,,note ,,viii4 7p4 #ada74 #ab ---------------------------------------- --------------------------------- ,nitrogen as nitrates4 --------------------------------- ,amount of ,per million of ,per acre4 ,rainfall drainage4 water4 ---------------------------------------- ------- #bj-;inch #fj-;inch #bj-;inch #fj-;inch #bj-;inch #fj-;inch gauge4 gauge4 gauge4 gauge4 gauge4 gauge4 ---------------------------------------- ----------------------------- ,inches4 ,inches4 ,inches4 lb4 lb4 ,march #a4gj #j4he #j4id #g4c #h4i #a4da #a4hi ,april #b4be #j4gb #j4gi #h4c #i4j #a4ce #a4fa ,may #b4dh #j4hj #j4gi #h4d #i4a #a4ec #a4fc ,june #b4ei #j4gh #j4gh #i4b #i4a #a4fb #a4fj ,july #b4he #j4fh #j4fb #ac4e #aa4h #b4jh #a4ff ,august #b4fi #j4hd #j4gf #ae4a #ac4c #b4hg #b4bh ,september #b4gj #j4ig #j4hb #ag4g #ac4d #c4hf #b4ej ,october #c4ab #a4hf #a4fh #ac4h #aa4i #e4hc #d4ec ,november #c4bj #b4dd #b4cb #aa4h #aa4d #f4ej #e4ih ,december #b4cd #a4hh #a4hh #i4e #aj4f #d4jf #d4ea ,january #b4ac #a4gi #a4ic #g4d #h4i #b4ii #c4hh ,february #b4af #a4hd #a4gd #g4g #i4a #c4ai #c4eg ---------------------------------------- --------------- ,march-,june #i4jb #c4ae #c4cj #h4c #i4j #e4ia #f4gc ,july-,september #h4bd #b4di #b4bj #ae4f #ac4j #h4ha #f4dd ,october-,feb4 #ab4ie #i4ha #i4ee #aj4b #aj4d #bb4eg #bb4dg ---------------------------------------- --------------- ,whole year #cj4ba #ae4de #ae4je #aj4g #aj4e #cg4bi #ce4fd ---------------------------------------- ----------------------------- ,,chapter ,,iv4 ,,nitrification4 ,the most important compound of nitrogen for the plant is nitric acid4 ,it is as nitrates that most plants absorb the nitrogen they require to build up their tissue4 ,in nature the nitrogen1 present in the soil as ammonia and different organic forms1 is constantly being converted into nitric acid4 ,this conversion of nitrogen into nitrates1 known as nitrification1 is a process of very great importance1 and1 as has been already pointed out in the ,introductory ,chapter1 is effected through the agency of micro-organisms 7ferments74#ig ,the process of nitrification1 as well as the nature of the other changes taking place in the soil between the various compounds of nitrogen1 are as yet but most imperfectly understood1 but much light has been thrown on this most interesting department of agricultural research during the last few years2 and it cannot be doubted that the increased attention which it is receiving from different investigators1 both on the ,continent and in this country1 will be fraught with most important results for practical agriculture4 ,occurrence of ,nitrates in the ,soil4 ,the occurrence of nitre1#ih or potassium nitrate1 in soils has been long known1 although it is only within the last few years that we have obtained any precise knowledge with regard to the mode of its production4 ,while its amount in most soils1 especially in this country1#ii is very minute1 there are certain parts of the world where nitrates are found in large quantities4 ,the nitrate fields of ,chili and ,peru are the chief natural sources of nitrates1 and they are referred to in the chapter on ,nitrate of ,soda4 ,we have other parts of the world1 however 7in ,china and ,india71 where soils rich in nitre occur1 and which in the past have formed a source of the commercial article4#ajj ,nitre ,soils of ,india4 ,the most important of these nitre soils are those found in the ,north-west of ,india1 in the province of ,bengal4 ,in these districts the soil is of a light porous texture1 rich in lime1 and situated at a considerable height above water-level4 ,they are the sites of old villages1 and the nitre is found in the form of an efflorescence on the surface of different parts of the soil4 ,the occurrence of nitre under such conditions is due1 partly to the natural richness of the soil in nitrogen1 and partly to its artificial enrichment through receiving the nitrogenous excrements of the inhabitants of the villages and their cattle4 ,the constant process of evaporation going on in such a warm climate has the effect of inducing an upward tendency of the soil-water1 the result being a concentration of all the nitre the soil contains in its surface layer4 ,this goes on until a regular incrustation is formed1 and the soil is covered by a white deposit of nitre4 ,whenever this becomes apparent1 the surface portion of the soil is scraped off by the sorawallah1 or native manufacturer1 and collected and treated for the purpose of recovering1 in a pure state1 the saltpetre4 ,saltpetre ,plantations4 ,the large demand for saltpetre1 larger than could be supplied by these nitre soils1 soon gave rise to the semi-artificial method of production1 formerly so largely practised in ,switzerland1 ,france1 ,germany1 ,sweden1 and in many other parts of the ,continent1 by means of the so-called nitre beds1 nitraries1 or saltpetre plantations4 ,previous to the introduction of this method of manufacture1 the demand for saltpetre for gunpowder had become so great1 that every source of nitre was eagerly sought for4 ,thus1 when it was discovered that the earth from the floors of byres1 stables1 and farmyards were particularly rich in nitre1 and when mixed with wood-ashes formed an important source of it1 the right to remove these in ,france was vested in the ,government under the ,saltpetre ,laws1 which obtained till the ,french ,revolution4 ,this great scarcity soon led1 however1 to a careful investigation being made into the conditions under which potassium nitrate was formed in nitre soils4#aja ,these conditions1 which included the presence of rich nitrogenous matter1 warmth1 free aeration of the soil1 and a certain proportion of moisture1 became1 in the course of years1 more and more thoroughly understood1 and the result was the institution of numerous saltpetre plantations4 ,these generally consisted of heaps of mould1 rich in nitrogen1 mixed with decomposing animal matter1 rubbish of various kinds1 manurial substances1 ashes1 road-scrapings1 and lime salts4#ajb ,the heap was interlaid with brushwood1 and was watered from time to time with liquid manure from stables1 consisting chiefly of dilute urine4 ,in forming the heap care was taken to keep the mass porous1 so as to admit of the free access of air4 ,the heap was further protected from the rain by covering it with a roof4 ,in course of time considerable quantities of nitrates were developed1 and the nitre was occasionally collected by scraping it from the surface1 where it became concentrated just as in the nitre soils4 ,in all cases1 however1 the heaps1 when considered rich enough in nitre1 were treated from time to time with water which1 by subsequent evaporation1 yielded the nitre in a more or less pure condition4#ajc ,this mode of obtaining nitre is no longer practised to any extent1 since it is now more conveniently obtained from the treatment of nitrate of soda with potassium chloride4 ,cause of ,nitrification4 ,we have adverted to these nitre plantations as showing how the conditions most favourable for the development of nitrification were recognised long before anything was known as to the true nature of the process4 ,it was only in #ahgg that the formation of nitrates in the soil was proved to be due to the action of micro-organic life1#ajd by the two ,french chemists1 ,schloesing and ,muentz1 who discovered the fact when carrying out experiments to see if the presence of humic matter was essential to the purification of sewage by soil4 ,in these experiments sewage was made to filter slowly through a certain depth of soil 7the time occupied in this filtration being eight days74 ,it was found that nitrification of the sewage took place4 ,by treating the soil with chloroform#aje it was found that it no longer possessed the power of inducing the nitrification of the sewage4 ,when1 however1 a small portion of a nitrifying soil was added1 the power was regained4 ,from this it was naturally inferred that nitrification was effected by some kind of ferment4 ,this conclusion was soon confirmed by subsequent experiments by ,warington at ,rothamsted1 who showed that the power of nitrification could be communicated to media1 which did not nitrify1 by simply seeding them with a nitrifying substance1 and that light was unfavourable to the process4 ,since then the question has formed the subject of a number of researches by ,mr ,warington at ,rothamsted1 as well as by ,schloesing and ,muentz1 ,munro1 ,deherain1 ,p4 ,f4 ,frankland1 ,winogradsky1 ,gayon and ,dupetit1 ,kellner1 ,plath1 ,pichard1 ,landolt1 ,leone1 and others4 ,from these researches we have obtained the following information with regard to the nature of the organisms concerned in this process1 and the conditions most favourable for their development4 ,ferments effecting ,nitrification4 ,the importance of isolating and studying them microscopically was recognised at an early period in these researches4 ,messrs ,schloesing and ,muentz were the first to attempt this4 ,they reported that they had successfully accomplished this1 and described the organism as consisting of very small1 round1 or slightly elongated corpuscles1 occurring either singly or two together4 ,according1 however1 to the most recent researches of ,warington1 ,winogradsky1 and ,p4 ,f4 ,frankland1 nitrification is not effected by a single micro-organism1 but by two1 both of which have been successfully isolated and studied4#ajf ,the first of these to be discovered and isolated was the nitrous organism1 which effects the conversion of ammonia into nitrous acid2 the second1 which has only been lately isolated by ,warington and ,winogradsky1 effects the conversion of nitrous acid into nitric acid4 ,each of these ferments thus has its distinctive function to perform in this most important process1 the nitric ferment being unable to act on ammonia1 as the nitrous ferment is unable to convert nitrites into nitrates4 ,both ferments occur in enormous quantities in the soil1 and seem to be influenced1 so far as is at present known1 by the same conditions4 ,their action will thus proceed together4 ,nearly all we know as yet on the subject of their nature is with regard to the nitrous ferment4 ,appearance of ,nitrous ,organism4 ,mr ,warington#ajg thus describes the appearance of the nitrous organism3 ,as found in suspension in a freshly nitrified solution1 it consists largely of nearly spherical corpuscles1 varying extremely in size4 ,the largest of these corpuscles barely reaches a diameter of #a_/ajjjth of a millimeter2 and some are so minute as to be hardly discernible in photographs1 although shown there with a surface one million times greater than their own4 ,the larger ones are frequently not strictly circular4 ,these forms are universally present in nitrifying cultures4 ,the larger organisms are sometimes seen in the act of dividing4 ,nitric ,organism4 ,so far as at present known1 the nitric organism is very similar in appearance to the nitrous organism1 so much so that it is difficult to distinguish the one from the other4 ,as the same conditions influence their development1 the process may be regarded as a whole4 ,difficulty in isolating them4 ,a great difficulty has been experienced in the attempt to isolate these micro-organisms for the purpose of studying their nature4 ,this arises from the fact that they refuse to grow on the ordinary solid cultivating media used by bacteriologists4 ,winogradsky1 however1 has recently succeeded in cultivating them in a purely mineral medium--viz41 silica-jelly4#ajh ,nitrifying ,organisms do not require ,organic ,matter4 ,the fact that they can develop in media destitute of organic matter1 is one of very great interest and importance to ,vegetable ,physiology4 ,it implies that they can derive their carbon from carbonic acid--a power which it was believed was possessed by green plants alone among living structures4 ,for organisms destitute of chlorophyll1 the source of their protoplasmic carbon1 it has been hitherto commonly believed1 must be organic matter of some sort4 ,while it would appear that the nitrifying organisms can1 when opportunity affords1 feed upon organic matter1 yet it has been proved beyond doubt that they can also freely develop in media entirely devoid of it1 and are capable1 under such circumstances1 of deriving their carbon from a purely mineral source4#aji ,this fact1 which is subversive of what was believed to be a fundamental law of ,vegetable ,physiology1 is one of the most important of the many important and interesting facts which these nitrification researches have elicited4#aaj ,,conditions ,,favourable ,,for ,,nitrification4 ,we may now proceed to discuss the conditions favourable for nitrification4 ,presence of ,food-constituents4 ,among these conditions the first is the presence of certain food-constituents4 ,to both animal and vegetable life alike a certain amount of mineral food is absolutely necessary4 ,among these phosphoric acid is one of the most important1 and in the experiments on nitrification it has been found that the nitrifying organisms will not develop in any medium destitute of it4 ,that other mineral food-constituents are necessary is highly probable1 although the influence of their absence on the development of the process has not been similarly studied4 ,probably potash1 magnesia1 and lime salts are necessary4 ,in the cultivating solutions used in the experiments on the subject1 the mineral food-constituents added consisted of lime1 magnesia1 and potash salts and phosphoric acid4#aaa ,as we have seen above1 the presence of organic matter is not necessary for the process4 ,in this respect these organisms are differentiated from all other ferments hitherto discovered4 ,presence of a ,salifiable ,base4 ,the presence of a sufficient quantity of a base in the soil with which the nitric acid may combine1 when it is formed1 is another necessary condition4#aab ,the process only goes on in a slightly alkaline solution4 ,the substance which acts as this salifiable base is lime4 ,the presence of a sufficient quantity of carbonate of lime in the soil will thus be seen to be of first-rate importance4 ,this furnishes an explanation of one of the many benefits conferred by lime on soils4 ,the activity of nitrification in many soils may be hindered by the absence of a sufficiency of lime salts1 and in such cases most striking results may follow the application of moderate dressings of chalk4 ,the absence of the nitrifying organisms in certain soils1 such as peaty and forest soils1 may be thus accounted for4 ,in such soils humic acids are present and the requisite alkalinity is thus awanting4 ,only takes place in slightly ,alkaline ,solutions4 ,but while a certain slight amount of alkalinity is necessary1 this must not exceed a certain strength1 otherwise the process is retarded4 ,this is the reason why strong urine solutions do not nitrify4 ,the amount of carbonate of ammonia generated in them by putrefaction renders the development of nitrification impossible by rendering the alkalinity of the solution too great4#aac ,the practical importance of this fact is considerable1 as it shows the importance of diluting urine very considerably before applying it as a manure4 ,similarly1 when large quantities of lime1 especially burnt lime1 are applied to soils1 the result will be to arrest the action of nitrification for the time4 ,the presence of alkaline carbonates in the soil1 unless in minute quantities1 is apt1 therefore1 to seriously interfere with the process4#aad ,action of ,gypsum on ,nitrification4 ,it has been found by ,pichard that the action of certain mineral sulphates is extremely favourable to the process1 and among these gypsum4 ,warington has carried out some experiments on the action of gypsum in promoting nitrification4 ,the reason of its favourable action is probably because it neutralises the alkalinity of nitrifying solutions4 ,it thus permits the process to go on in unfavourable conditions4 ,where1 therefore1 too great alkalinity exists for the maximum development of nitrification1 the best specific will be found to be gypsum4#aae ,the practical value of gypsum as an adjunct to certain manurial substances1 where nitrification is desired to be promoted as rapidly as possible1 such as sewage and farmyard manure1 will thus at once become apparent4 ,so far as there is a proper degree of alkalinity maintained1 the presence of large quantities of saline matter does not seem to interfere with the process4 ,presence of ,oxygen4 ,the nitrification bacteria belong1 it would seem1 to the aerobic#aaf class of ferment--i4e41 they cannot develop without a free supply of oxygen4 ,exclusion of the air is sufficient to kill them1 and in those portions of the soil where access of air is not freely permitted1 nitrification will be found to be correspondingly feeble4 ,thus it has been found in experiments with different portions of soils1 that but little signs of nitrification occur in the lower soil layers4 ,according to experiments by ,schloesing on a moist soil1 in atmospheres respectively containing no oxygen and varying quantities of it1 the action of oxygen in promoting nitrification was strikingly demonstrated4 ,in an atmosphere of pure nitrogen1 entirely devoid of oxygen1 the process no longer took place1 but the nitrates already present in the soil were reduced and free nitrogen was evolved4 ,in an atmosphere1 on the other hand1 containing #a4e per cent of oxygen1 a considerable amount of nitrification took place2 while in the presence of #f per cent1 nitrification took place to double the extent4 ,an addition of #aj to #ae per cent again doubled the quantity4 ,when the amount of moisture added was increased1 the effect of larger percentages of oxygen was found to be less marked4 ,the reason of this is that the oxygen probably acts as dissolved oxygen2 the addition of water meaning at the same time an addition of available oxygen4 ,this condition exemplifies the value of tillage operations4 ,the more thoroughly a soil is tilled the more thoroughly will the aeration of its particles take place1 and consequently the more favourable will this necessary condition of nitrification be rendered4 ,the benefits conferred on clayey soils by tillage will in this respect be especially great4 ,temperature4 ,another of the conditions determining the rate at which nitrification takes place1 and one which is most important1 is ,temperature4 ,according to ,schloesing and ,muentz the temperature at which maximum development takes place is #cg deg4 ,c4#aag 7#ii deg4 ,f471 at which temperature it is ten times as active as at #ad deg4 ,c4 7#eg deg4 ,f47 ,below #e deg4 ,c4 7#dj deg4 ,f47 the action is extremely feeble4 ,it is clearly appreciable at #ab deg4 ,c4 7#ed deg4 ,f471 and from there up to #cg deg4 ,c4 7#ii deg4 ,f47 it rapidly increases4 ,from #cg deg4 ,c4 7#ii deg4 ,f47 to #ee deg4 ,c4 7#aca deg4 ,f471 at which temperature no nitrification takes place1 its activity decreases2 at #de deg4 ,c4 7#aac deg4 ,f47 it is less active than at #ae deg4 ,c4 7#ei deg4 ,f471 and at #ej deg4 ,c4 7#abb deg4 ,f47 it is very slight4 ,these results by ,schloesing and ,muentz have not been exactly confirmed by ,warington4 ,he has found that a considerable amount of nitrification goes on at a temperature between #c deg4 and #d deg4 ,c4 7#cg deg4 and #ci deg4 ,f471 while the highest temperature at which he has found it to take place is considerably lower than #ee deg4 ,c4 7#aca deg4 ,f47 ,thus he was unable to start nitrification in a solution maintained at #dj deg4 ,c4 7#ajd deg4 ,f47 ,it would thus seem that the nitrifying ferments are able to develop at lower temperatures than most organisms2 and although nitrification entirely ceases during frost1 yet in a climate such as our own there must be a considerable proportion of the winter during which nitrification is moderately active4 ,presence of a sufficient quantity of ,moisture4 ,the presence of moisture in a soil is another of the necessary conditions of nitrification4 ,it has been shown that it is at once arrested1 and indeed destroyed1 by desiccation4 ,other conditions being equal1 and up to a certain extent1 the more moisture a soil contains the more rapid is the process4 ,too much water1 however1 is unfavourable1 as it is apt to exclude the free access of air1 which1 as we have just shown1 is so necessary1 as well as to lower the temperature4 ,during a period of drought the rate at which nitrification takes place will1 therefore1 be apt to be seriously diminished4 ,absence of strong ,sunlight4 ,it has been found that the process goes on much more actively in darkness2 indeed ,warington has found in his experiments that nitrification could be arrested by simply exposing the vessel in which it was going on to the action of sunshine4 ,nitrifying ,organisms destroyed by ,poisons4 ,it has already been pointed out that nitrification is arrested by the action of antiseptics1 such as chloroform1 bisulphide of carbon1 and carbolic acid4 ,another substance which has been found to have an injurious action is ferrous sulphate or copperas1 a substance which is apt to be present in badly drained soils1 or soils in which there is much actively putrefying organic matter4 ,maercker has found that in moor soils containing ferrous sulphate1 no nitrates1 or mere traces of nitrates1 could be found4 ,a substance such as gas-lime1 unless submitted to the action of the atmosphere for some time1 would also have a bad effect in checking nitrification1 owing to the poisonous sulphur compounds it contains4 ,common salt1 it would seem1 also arrests the process2 and this antiseptic property which salt exercises on nitrification throws a certain amount of light on the nature of its action when applied1 as it is often done1 along with artificial nitrogenous manures4 ,denitrification4 ,in connection with the process of nitrification1 it is of interest to notice that a process of an opposite nature may also take place in soils--viz41 denitrification--a process which consists in reducing the nitrates to nitrites1 nitrous oxide1 or free nitrogen4 ,that a reduction of nitrates takes place in the decomposition of sewage with the evolution of free nitrogen1 was a fact first observed by the late ,dr ,angus ,smith in #ahfg2 and the reduction of nitrates to nitrites1 and nitric and nitrous oxides in putrefactive changes has been subsequently noticed by different experimenters1 who have further observed that such reduction takes place in the case of putrefaction going on in the presence of large quantities of water or where there is much organic matter4 ,denitrification also effected by ,bacteria4 ,this change was supposed to be of a purely chemical nature1 and it has only been recently discovered that it is effected1 like nitrification1 by means of bacteria4 ,it has been surmised by some that the action of denitrification may be effected by the same organisms that effect nitrification1 and that it depends on merely external conditions which process goes on4 ,there is no reason1 however1 to suppose that this is so1 and several of the denitrifying organisms have been identified4 ,conditions favourable for ,denitrification4 ,that it is a process that goes on to any extent in properly cultivated soils is not to be supposed4 ,the conditions which favour denitrification are exactly the opposite of those which favour nitrification4 ,it is only when oxygen is excluded1 or1 which practically means the same thing1 when large quantities of organic matter are in active putrefaction1 and the supply of oxygen is therefore deficient1 that denitrification takes place4 ,schloesing1 as we have already seen1 found that in the case of a moist soil1 kept in an atmosphere devoid of oxygen1 a reduction of its nitrates to free nitrogen took place4 ,takes place in water-logged ,soils4 ,the exclusion of oxygen from a soil may be effected by saturating the soil with water2 and ,warington has found in experiments carried out in an arable soil1 by no means rich in organic matter1 that complete reduction of nitrates may be effected in this way4 ,it would thus seem that the process of denitrification will take place in water-logged soils1 or in the putrefaction of sewage matter in the presence of large quantities of water4 ,whether this reduction will result in the production of nitrites1 nitrous oxide1 or free nitrogen1 depends on different conditions4 ,this process is one of great importance from an economic point of view1 as it reveals to us a source of loss which may take place in the fermentation of manures4 ,in the rotting of our farmyard manure it is possible that the denitrifying organisms may be more active than we have hitherto suspected1 and that a considerable loss of nitrogen may in this way be effected4 ,distribution of the ,nitrifying ,organisms in the ,soil4 ,the nitrifying organisms are probably chiefly confined to the soil1 and do not usually occur in rain or in the atmosphere4 ,that1 however1 they are found in spots which we might be inclined to think extremely unlikely1 is shown by some recent interesting researches carried out by ,muentz1 who discovered that the bare surfaces of felspathic1 calcareous1 schistose1 and other rocks at the summit of mountains in the ,pyrenees1 ,alps1 and ,vosges1 yielded large numbers of them1 and that they occurred to a considerable depth in the cracks and fissures of the rocks4 ,the nitrifying organisms are also found in river-water1 in sewage1 and well-waters4 ,depth down at which they occur4 ,in ,warington's earlier experiments1 the conclusion he arrived at was that the occurrence of the nitrifying organisms was almost entirely limited to the superficial layers of the soil1 and that they were seldom to be met with much below a depth of #ah inches4 ,his subsequent experiments1 however1 considerably modified this conclusion1 and showed that nitrification may take place to a depth of at least #f feet4#aah ,but although it may take place at this depth1 it probably1 as a general rule1 is limited to the surface-soil1 as it is only there the conditions for obtaining circulation of air are sufficiently favourable4 ,a great deal1 of course1 will depend on the nature of the soil--i4e41 as to its texture4 ,in a clayey subsoil the principal hindrance to nitrification will be the difficulty of obtaining sufficient aeration4 ,in clay soils it is probable1 therefore1 that nearly all the nitrification goes on in the surface layer2 in sandy soils it may take place to a greater depth4#aai ,action of ,plant-roots in promoting ,nitrification4 ,in this connection the action of plant-roots in permitting a more abundant access of air to the lower layers of the soil1 and thus promoting nitrification1 is worth noticing4 ,this has been observed in the case of different crops4 ,thus the action of nitrification has been found to be more marked in the lower layers of a soil on which a leguminous crop was growing than on that on which a gramineous4 ,the conditions which would favour nitrification in the subsoil are such as would enable air to penetrate it1 as artificial drainage1 a dry season1 the growth of a luxuriant crop causing much evaporation of the water in the soil4 ,such conditions1 by removing the water that fills the pores of the subsoil1 will cause the air to penetrate more or less deeply and render nitrification possible4 ,subsoil nitrification will thus be most active in the drier periods of the year 7,warington74 ,nature of ,substances capable of ,nitrification4 ,what kinds of nitrogenous substances are capable of undergoing this process of nitrification are not yet well known4 ,the question is1 of course1 one of great importance1 as the rapidity with which a nitrogenous body nitrifies will be an important factor in determining its value as a manure4 ,unfortunately1 on this subject we know1 as yet1 very little4 ,we are well aware that the nitrogen present in the humic matter of the soil is readily nitrifiable4 ,in the experiments on nitrification the nitrogenous bodies used have been chiefly ammonia salts1 so that it is difficult to say whether1 in the case of other nitrogenous substances1 micro-organic life of a different sort has not also been active and has converted the nitrogen into ammonia1 and thereby prepared the way for the process of nitrification4 ,that various manures1 such as bones1 horn1 wool1 and rape-cake are readily nitrifiable1 has been shown by experiment4 ,laboratory experiments have also been carried out on such different nitrogenous substances as ethylamine1 thiocyanates1 gelatin1 urea1 asparagin1 and albuminoids of milk4 ,but in all these experiments1 how far these bodies have been directly acted upon by the nitrifying organisms1 or how far they have first undergone a preparatory change in which their nitrogen has been first converted into ammonia1 is impossible to say4 ,it is at least quite probable that all the organic forms of nitrogen have first to be converted into ammonia ere they are nitrified4 ,rate at which ,nitrification takes place4 ,a question which is practically of no little importance is the rate at which nitrification takes place4 ,from what has been already said as to the nature of the conditions favourable for the process1 it will be at once seen that this will depend on how far these conditions are present in the soil4 ,in point of fact the rate at which nitrification takes place will vary very much in different soils4 ,a greater difference1 however1 in the rate at which it takes place1 will be found even in the same soils at different periods of the year4 ,in this country1 where the most favourable temperature for its development is seldom reached1 it never goes on at the same rate as in tropical climates4 ,one of the causes of the greater fertility of tropical soils is due1 doubtless1 to the very much longer duration of the period of nitrification1 as well as to its greater intensity4 ,as1 however1 temperature is not the only condition1 and the presence of moisture is quite as necessary1 it may be that its development is seriously retarded in many tropical climates by the extreme dryness of the soil during long periods4 ,takes place chiefly during the ,summer ,months4 ,although in this climate1 as has already been pointed out1 nitrification probably goes on during most of the winter months1 owing to the fact that the temperature of our soils is only occasionally below the minimum temperature at which the process takes place1 yet there can be little doubt that the great bulk of the soil-nitrates are produced during a few months in summer4 ,a fair conception of this amount is afforded by the interesting experiments on the composition of drainage-waters made at ,rothamsted1 which we shall have occasion to refer to immediately4 ,it may be pointed out1 however1 that it is not always safe to take the amount of nitrates found in drainage-waters as an infallible indication of this rate1 for this amount will depend to a certain extent on the amount of rainfall1 and would be misleading in the case of a long period of drought4 ,on the whole1 however1 it furnishes us with extremely useful data for the elucidation of this important problem4 ,process goes on most quickly in ,fallow ,fields4 ,it has been shown in the ,rothamsted experiments that the process goes on best in fields lying in bare fallow2 and in this fact lies the explanation of one of the many reasons why the practice of leaving fields in bare fallow1 so common in past times1 and still practised in the case of clay soils in some parts of the country1 was so beneficial to the land thus treated4 ,but despite this fact1 the practice of leaving soils in bare fallow can scarcely be justified from this point of view1 as the loss of nitrates through the action of rain is very great in our moist climate4 ,laboratory ,experiments on ,rate of ,nitrification4 ,several interesting experiments have been carried out with the object of affording data for estimating the rate at which the process may go on in our soils under certain conditions4 ,an old experiment1 carried out by ,boussingault1 illustrates1 in a general way1 how rapid the process is under favourable circumstances4 ,a small portion of rich soil was placed on a slab protected by a glass roof1 and was moistened from time to time with water4 ,the amount of nitrate of potash formed under these circumstances was estimated from time to time during a period of two months4 ,during the first month 7,august7 the percentage was increased from 4#ja to 4#ah 7equal to about #e cwt4 of nitrate of potash per acre74 ,the increase during the second month 7,september7 was very much less1--indeed only about a seventh of the amount4#abj ,the soil experimented with was an extremely rich garden soil1 and all the conditions for nitrification were most favourable4 ,of recent experiments on the rate of nitrification1 the most striking1 perhaps1 are those by ,schloesing4 ,he mixed sulphate of ammonia with a quantity of soil fairly rich in organic matter1 and containing #ai per cent of water4 ,during the twelve days of active nitrification no less than #ef parts of nitrogen per million of soil were nitrified per day4 ,taking the soil to a depth of #i inches1 this would be equal to more than #a cwt4 per acre--an amount of nitrogen equal to that contained in #f cwt4 of commercial nitrate of soda4 ,these experiments are interesting as showing what is probably the maximum rate of nitrification under the most favourable circumstances1 and where there is an abundant supply of easily nitrifiable nitrogen4 ,that nitrification ever takes place in our soils to this extent is not to be for a moment supposed4 ,warington1 in his ,rothamsted experiments1 has found that the greatest rate1 working with ordinary arable soil 7first #i inches7 from the ,rothamsted farm1 was 4#ehh parts per million of air-dried soil per day--i4e41 #a4c lb4 per acre 7equal to about #h lb4 of nitrate of soda74 ,similar soil1 when supplied with ammonia salts1 showed nearly double this quantity4 ,higher results were obtained by ,lawes and ,gilbert with rich ,manitoba soils1 the average rate being 4#g parts per million per day4 ,the last of these interesting laboratory experiments on the rate of nitrification we shall refer to1 are those by ,deherain4 ,he experimented with soils containing different amounts of nitrogen and moisture4 ,with a soil containing 4#af per cent of nitrogen he obtained1 during a period of #ij days1 rates of nitrification varying from 4#ga to #a4ji per million parts of soil4 ,the maximum quantity was formed when the soil contained #be per cent of moisture4 ,on a soil considerably richer--viz414#bfa per cent of nitrogen--a higher rate of nitrification took place--#a4dh parts per million4 ,the highest rate obtained in these experiments showed1 when calculated to pounds per acre1 about #e-a_/b1 taking the soil to a depth of #i inches4 ,when the soil was alternately dried and moistened the process was most rapid4 ,portion of ,soil-nitrogen more easily ,nitrifiable than the rest4 ,lastly1 it may be noticed that in the above-cited experiments1 and others of a similar kind1 the process goes on most rapidly at first1 and steadily diminishes thereafter4 ,this is due to the fact1 that there is generally a certain quantity of nitrogen in most soils in a more easily nitrifiable condition than the rest1 so that when this becomes oxidised nitrification proceeds more slowly4 ,it would further seem that the nitrogen of the subsoil is less easily nitrified than that of the surface-soil4 ,rate of ,nitrification deduced from ,field ,experiments4 ,while the above experiments throw much light on the question of the rate at which nitrification may go on under different circumstances1 the results furnished by actual analyses of soils and their drainage-waters are of still more practical value2 and the ,rothamsted experiments fortunately furnish us with a number of these valuable results4 ,quantity of ,nitrates formed in the soils of ,fallow ,fields4 ,these researches had to be carried out on soil taken from fields lying in bare fallow2 for no true estimate of the amount of nitrates formed could have been obtained from cropped fields4 ,in the first #bg inches of soil of six separate fields1 nitrate-nitrogen was found to vary from #cf4c lb4 to #ei4i lb4 per acre4 ,in four of these fields the largest proportion was found in the first #i inches of soil2 in the remaining two1 in the second #i inches2 while the third #i inches in two fields showed almost as large a proportion as the first #i inches4#aba ,position of ,nitrates depends on ,season4 ,the position of nitrates in the soil depends largely on the season2 for1 as has been already pointed out1 their production is almost entirely limited to the surface-soil1 and it is only by being washed down in rain that they find their way to the lower layers4 ,a wet season1 therefore1 has the effect of increasing their percentage in the lower soil-layers4 ,nitrates in ,drainage-waters4 ,as there is a certain proportion of nitrates that finds its way even below the first #bg inches of soil1 the above results do not show their total production4 ,to accurately estimate this amount we must ascertain the quantity escaping in drainage-water4 ,here1 again1 the ,rothamsted experiments furnish us with valuable data4 ,the amount found in drainage-waters of course naturally varies very much1 and depends largely on the rainfall2 but taking an average of twelve years1 this has been found to amount to between #cj and #dj lb4 per acre--an amount not so very far short of that found in the first #bg inches of the soil itself4 ,this was from comparatively poor soil1 it must be remembered1 and a much larger quantity would undoubtedly be produced in the case of richer soils4 ,adding then the results together1 we find that in soils like those at ,rothamsted1 when in bare fallow1 between #hj and #ij lb4 of nitrogen are converted into nitrates in some fourteen months' time--an amount equal to about #e cwt4 of nitrate of soda4 ,it is a fact of no little practical significance that nearly one-half of this large quantity is found in the drainage-water4 ,amount produced at ,different ,times of the ,year4 ,some indication of the rate at which nitrification takes place during the different months of the year is obtained from a study of the results of the analyses of drainage-waters which we have just referred to4 ,this1 however1 it must be remembered1 only furnishes us with a very approximate indication4 ,the month showing the greatest amount of nitrates in the drainage-water must not necessarily be regarded as that during which nitrification has been most active1 for the amount chiefly depends on the rainfall4 ,in illustration of this it will be found that the drainage-water during the autumn and early winter months contains most nitrates1 not because nitrification is most active then1 but because the rainfall is greatest1 and a large proportion of the nitrates formed during the drier summer months is being only then washed from the soil4 ,the amount of nitrates in drainage-waters steadily diminishes from autumn through the winter months1 and is least in spring4 ,the total amount of nitrates found in the drainage-water is1 therefore1 not a safe guide4 ,what1 however1 does furnish us with a more reliable indication is the percentage of nitrates in the drainage-water4 ,regarding the results of the analyses of drainage-water 7see ,appendix7 from this point of view1 it will be seen that this is greatest during the month of ,september1 and least during ,april4#abb ,nitrification of ,manures4 ,a subject which has not yet been specially referred to1 but which is of great practical importance1 is the nitrification of manurial substances4 ,it is unfortunate that the amount of research hitherto devoted to this important question has been slight1 and that the knowledge we possess is therefore very limited4 ,ammonia ,salts most easily ,nitrifiable4 ,one fact1 however1 about which there can be little doubt1 is that nitrogen in the form of ammonia salts is1 of all compounds of nitrogen1 the most easily nitrifiable4 ,indeed1 as we have already indicated1 it is highly probable that the conversion of the different forms of organic nitrogen into ammonia is an intermediate stage in the nitrification of these bodies4 ,at any rate it seems to be invariably the case that when a mixture of nitrogen compounds1 including ammonia salts1 are allowed to nitrify1 the nitrogen in the form of ammonia is the first to become nitrified4 ,sulphate of ,ammonia most easily ,nitrifiable ,manure4 ,it follows from this that sulphate of ammonia1 the most common of ammoniacal manures1 is one of the most speedily nitrified when applied to the soil4 ,the rate at which the nitrification of this manure takes place naturally varies according to the quantity applied1 and other circumstances1 such as the nature of the soil and the weather1 c4 ,that1 under favourable circumstances1 the conversion of ammonia into nitrates is very rapid1 has been shown by a number of experiments4 ,deherain has found that when sulphate of ammonia was mixed with soil at the rate of #b cwt4 per acre1 nitrification took place at the rate of #a_/ajjth of its nitrogen per day4 ,rate of ,nitrification of other ,manures4 ,of other nitrogenous manures1 guano1 it would seem1 comes next to sulphate of ammonia in the rate at which it becomes nitrified in the soil2 while next to guano stand green manures1 dried blood1 meat-meal1 c4 ,as we should expect1 such a manure as shoddy is very slowly nitrified4 ,the rate at which the nitrogen compounds in farmyard manure become nitrified1 when incorporated with the soil1 vary very much according to circumstances4 ,it goes on probably at a greater rate than the ordinary nitrification of soil-nitrogen4 ,it is a somewhat striking fact that the effect of adding nitrate of soda to the soil may be at first to check nitrification4 ,that the addition of common salt1 even in small quantities1 has this result1 is at any rate certain4 ,the presence of salt to the extent of one-thousandth of the weight of the soil1 has a prejudicial effect4 ,soils best suited for ,nitrification4 ,to recapitulate1 then1 nitrification is effected through the agency of micro-organisms1 which are present to a greater or less extent in all soils4 ,it requires for its favourable development air1 warmth1 moisture1 absence of strong light1 presence of a salifiable base--viz41 carbonate of lime--the presence of certain mineral food-constituents1 such as phosphates1 and a certain amount of alkalinity4 ,it consequently takes place to the least extent in barren sandy soils4 ,soils rich1 light1 well ventilated1 uniformly moist1 warm1 and chalky1 are best suited for its development4 ,other things being equal1 it develops better in a fine-grained soil than in a coarse-grained soil1 because1 in the case of the former1 aeration and uniform moistening of the soil are best secured4 ,absence of ,nitrification in ,forest-soils4 ,a point of considerable interest is the practical absence of the process in forest-soils4 ,the absence1 or occurrence in the most minute traces1 of nitrates in forest-soils has been accounted for by the lowness of the normal temperature of such soils and their extreme dryness4 ,this latter condition is accounted for by the enormous transpiration of water which takes place through the trees1 especially in summer-time1 which is such as to render the soil almost air-dry4 ,lastly1 it may be accounted for by the want of mineral food ingredients4 ,important ,bearing of ,nitrification on ,agricultural ,practice4 ,before concluding this chapter1 it may be well to draw attention to the important bearing which nitrification has on agricultural practice4 ,the light which our present knowledge--imperfect as it is--of this most interesting process throws on the theory of the rotation of crops is very striking1 for it shows how the adoption of a skilful rotation may be made to prevent the loss of enormous quantities of the most valuable of all our soil-constituents1--the one on the presence of which fertility may be said most to depend--viz41 nitrogen4 ,desirable to have ,soil covered with ,vegetation4 ,the constant production of nitrates going on in the soil1 the inability of the soil to retain them1 and the consequent risk of their being removed in drainage1 furnish a strong argument in favour of keeping our soils as constantly covered with vegetation as possible4 ,permanent ,pasture most ,economical ,condition of ,soil4 ,from the point of view of conservation of soil-nitrates1 permanent pasture may be said to be the most economical condition for the soil to be in4 ,in such a case the nitrates are assimilated as they are formed1 and1 by being converted in the plant into organic nitrogen1 they are at once removed from all risk of loss4 ,a consideration1 therefore1 of the process of nitrification furnishes many arguments in favour of laying down land in permanent pasture--a practice which of late years has been increasingly followed in many parts of the country4 ,as1 however1 it is not possible or desirable to carry out this practice beyond certain limits1 the rotation which most nearly conforms to the condition of keeping the soil covered with vegetation1 and most approximates in this respect to permanent pasture1 is most to be recommended4 ,nitrification and ,rotation of ,crops4 ,the chief risk of loss of nitrates is in connection with a cereal crop such as wheat4 ,where turnips follow wheat1 there is a period during which the soil is left uncovered1 and during which most serious loss of nitrates is apt to ensue4 ,the risk of loss is enhanced by the fact that the assimilation of nitrates by cereals ceases before the season of their maximum production in the soil4 ,the soil is then left bare of vegetation during the autumn1 which is the most critical period of all1 and the result must be serious loss4 ,in order to minimise this loss1 the practice of growing catch-crops has been had recourse to4 ,as1 however1 this practice will be dealt with elsewhere1 nothing further need here be said4 ,,footnotes3 #ig ,as the formation of nitrites is a stage in the process1 the term nitrification includes the formation of nitrites as well as nitrates4 #ih ,nitre seems to have been known as early as the thirteenth century4 #ii ,lawes and ,gilbert1 for example1 have shown that in the ,rothamsted soils it only amounts to a few parts per million of soil4 #ajj ,see ,appendix1 ,note ,i41 p4 #aif4 #aja ,the artificial production of nitre seems to have been first effected by ,glauber in the seventeenth century4 #ajb ,the lime-rubbish from old buildings1 especially those parts which have come in contact with the earth1 or plastering from the walls of damp cellars1 barns1 stables1 c41 have been found to be rich in nitrate of lime1 and1 as has been long well known1 constitute by themselves a valuable manure4 ,the formation of the nitrate of lime can be accounted for by the contact of the lime with nitrogenous matter of different kinds4 #ajc ,as much of the nitric acid in this solution was present as nitrate of lime1 it was usually treated with a solution of potassium carbonate1 the result being the precipitation of the lime as carbonate1 pure saltpetre being left in solution1 according to the following equation-- ,k#b;,,co#c ,ca7,,no#c7b #b ,,kno#c ,ca,c,o#c4 ,under the ,french mode of manufacture1 the process was considered to have developed satisfactorily when #ajjj lb4 of earth1 at the expiration of two years1 yielded #e lb4 of nitre4 #ajd ,pasteur had already in #ahfb expressed the opinion that nitrification might probably be in some way connected with ferments4 ,a4 ,mueller 7see ',journal of ,chemical ,society1' #ahgi1 p4 #bdi7 was the first to advance the opinion that nitrification was due to the action of a ferment4 ,this conclusion he was led to by the observation that while the ammonia in sewage was converted into nitric acid1 no change took place in solutions of ammonia or urine prepared in the laboratory4 #aje ,bisulphide of carbon and phenol 7carbolic acid7 have also been experimented with in connection with their antiseptic action on nitrification4 ,in these experiments the former had a similar effect to chloroform2 the phenol1 however1 while hindering it did not entirely suspend it1 due probably to the difficulty of bringing the phenol vapour into thorough contact with the soil-particles4 #ajf ,winogradsky has named the nitrous organism nitrosomonas1 and the nitric organism nitrobaeter4 #ajg ,from a series of ,lectures delivered by him in connection with ,lawes ,agricultural ,trust1 in the ,united ,states4 #ajh ,this silica-jelly consists of dialysed silicic acid1 ammonium sulphate1 potassium phosphate1 magnesium sulphate1 calcium chloride1 and magnesium carbonate4 #aji ,this fact is all the more striking when we remember that this decomposition of carbonic acid is best effected in the dark1 since light is prejudicial to nitrification4 #aaj ,see ,appendix1 ,note ,,ii41 p4 #aif1 and ,note ,,iii41 p4 #aig4 #aaa ,see ,appendix1 ,note ,v41 p4 #aih4 #aab ,this is shown by the fact that nitrification will only continue in a solution of carbonate of ammonia till one-half the ammonia is nitrified4 ,it then stops4 ,the base1 with which the nitrous acid combines as it is formed1 being at that stage entirely used up1 nitrification is no longer possible4 ,with regard to urine solutions the same is the case4 ,nitrification thus will only take place where there is a sufficiency of base4 #aac ,see ,appendix1 ,note ,,iv41 p4 #aig4 #aad ,it would seem that an alkalinity much exceeding four parts of nitrogen per million is prejudicial to the process4 #aae ,according to ,warington1 solutions containing #ej per cent of urine become nitrifiable when sufficient gypsum is added4 ,the gypsum neutralises the alkalinity of nitrifying solutions by converting the alkaline ammonium carbonate into neutral ammonium sulphate1 the calcium carbonate being precipitated4 #aaf ,see ,chapter on ,farmyard ,manure4 #aag ,as practically illustrating this fact1 a solution kept at #aj deg4 ,c4 required ten days1 while a solution kept at #cj deg4 ,c4 required only eight days for nitrification4 #aah ,in sixty-nine trials no failure to produce nitrification by seeding with soil from a depth1 of #b feet was experienced4 ,similarly in eleven trials only one failure took place with soil from a depth of #c feet4 ,with clay soil from a depth of #f feet success took place to the extent of #ej per cent4 ,no nitrification was obtained with clay from a depth of #h feet4 ,entire failure was experienced with chalk subsoil4 ,the process thus diminishes in activity the lower down we go4 #aai ,koch has found that in soils he has examined few organisms were found at a depth below #c feet4 #abj ,see ,appendix1 ,note ,,vi41 p4 #aih4 #aba ,for full analytical results see ,appendix1 ,note ,,vii41 p4 #aih4 #abb ,we find the least amount in the month of ,april4 ,in the water1 from a #bj-;and #fj-;inch gauge respectively1 the amounts were #a4ce lb4 and #a4fa lb4 per acre 7rainfall #b4be inches74 ,from then on to ,november the amount steadily increases4 ,in the latter month it reaches its maximum--viz41 #f4ej lb4 7#bj-;inch gauge7 and #e4ih lb4 7#fj-;inch gauge7 per acre 7rainfall #b4cj inches74 ,see ,appendix to ,chapter ,,iii41 ,note ,,viii1 p4 #afj4 ,,appendix ,,to ,,chapter ,,iv4 ,,note ,i4 7p4 #afb74 ,,old ,,theories ,,of ,,nitrification4 ,according to the old theories1 nitrification was regarded as a simple case of the oxidation of nitrogen by the oxygen of the air1 or by ozone4 ,the union of nitrogen and oxygen1 however1 probably takes place only at very high temperatures1 such as are formed during electric discharges4 ,it is needless to point out that the union of nitrogen and oxygen in this way is not likely to occur in soils4 ,according to other theories1 nitrification was effected by means of the oxidation of ammonia4 ,ammonia1 however1 can only be oxidised to nitric acid by means of certain powerful oxidising agents1 such as ozone or hydrogen peroxide4 ,as1 however1 these substances are not found in the soil1 it is much to be doubted whether nitric acid is ever formed in the soil in this way4 ,it is possible1 however1 as held by some1 that ferric oxide is capable of inducing this conversion4 ,on the whole1 however1 most evidence points to the conclusion that all nitric acid produced in the soil is formed through the agency of micro-organic life4 ,,note ,,ii4 7p4 #agj74 ,the important fact that nitrification can take place in solutions practically devoid of organic matter1 was first shown by ,dr ,j4 ,h4 ,m4 ,munro 7',chemical ,society ,journal1' ,august #ahhf1 p4 #efa74 ,it was further corroborated by ,warington and ,p4 ,f4 ,frankland4 ,winogradsky1 however1 has carried out the most conclusive experiments on the subject4 ,he prepared vessels and solutions1 carefully purified from organic matter1 and these solutions he sowed with the nitrifying organism4 ,finding that under these conditions the nitrifying organism increased enormously and displayed its full vigour1 he proceeded further to determine the amount of carbonaceous organic matter formed in solutions after the introduction of the organism4 ,by making the nitrification intensive1 he was able to obtain considerable quantities of carbon from the nitrified solutions by the process of wet combustion4 ,in his third memoir he publishes figures which apparently show a close relation between the amount of nitrogen oxidised1 and the amount of carbon assimilated2 the ratio is about #ce3a4--,see ,bulletin of ,u4,s4 ,department of ,agriculture1 ,no4 #h1 containing ,lectures on ,rothamsted ,experiments by ,r4 ,warington1 ,f4,r4,s41 p4 #ej4 ,,note ,,iii4 7p4 #agj74 ,the oxidising power of the micro-organisms of soil is not confined to the oxidation of ammonia or of organic matter4 ,muentz has shown that soil is capable of oxidising iodides to hypo-iodides and iodates1 and bromides to hypo-bromides and bromates4 ,this is a very important result1 and seems to indicate that nitrification is part of a general oxidising action1 and that we must not assume that nitrites or nitrates are produced because they are in themselves of advantage to the organism4 ,,note ,,iv4 7p4 #agb74 ,when urine in different degrees of dilution was treated with soil1 #a gram of soil being added to #ajj c4c4 of diluted urine1 nitrification commenced in the #a-per-cent solution in #aa days1 in the #e-per-cent solution in #bj days1 in the #aj-per-cent solution in #fb days1 in the #ab-per-cent solution in #ij days4 ,the alkalinity of the last-named solution when nitrification commenced was equal to #ddg mgs4 of ammonia per litre4 ,a solution with an alkalinity of #ejj mgs4 of ammonia per litre is apparently unnitrifiable4--,american ,department of ,agriculture ,bulletin1 ,warington's ,lectures on ,rothamsted ,experiments1 p4 #ea4 ,,note ,v4 7p4 #aga74 ,professor ,p4 ,f4 ,frankland in his experiments used the following solutions3-- grms4 ,,nh#d;,cl 4#e ,h#c,,po#d 4#a ,mg,s,o#d 4#jb ,in #ajjj c4c4 of distilled water4 ,ca,cl#b 4#ja ,ca,c,o#c #e4jj ,,note ,,vi4 7p4 #ahe74 ,experiment by ,boussingault on ,rate of ,nitrification4 ,percentage of ,nitrate #aheg4 of ,potash4 lb4 per acre4 ,august #e 4#ja #cd ,august #ag 4#jf #bbb ,september #b 4#ah #fcd ,september #ag 4#bb #gfj ,october #b 4#ba #gbh ,,note ,,vii4 7p4 #ahh74 ,,nitrogen ,,as ,,nitrates ,,in ,,rothamsted ,,soils ,,after ,,bare ,,fallow ,,in ,,lb4 ,,per ,,acre4 ---------------------------------------- ------------------------------- ,alternate ,four-course rotation4 ,wheat -------------------------- ,depth of and ,super- ,claycroft ,foster's ,soil4 ,fallow4 phosphate ,mixed ,manure4 ,field4 ,field4 only4 ---------------------------------------- ----------------- #ahgh4 #ahgh4 #ahgh4 #ahhb4 #ahha4 #ahha4 ---------------------------------------- ----------------------------- lb4 lb4 lb4 lb4 lb4 lb4 #ast #i ins4 #bh4e #bb4c #cj4j #dj4a #af4d #ad4f #b;d #i ins4 #e4b #ad4j #ah4h #ad4c #bf4e #bd4f #c;d #i ins4 - - - #e4e #ae4i #ag4c ---------------------------------------- ----------------------------- ,total #cc4g #cf4c #dh4h #ei4i #eh4h #ef4e ---------------------------------------- ----------------------------- ,,chapter ,v4 ,,the ,,position ,,of ,,phosphoric ,,acid4 ,we now come to consider the position of phosphoric acid in agriculture4 ,the question is1 however1 very much simpler in its nature than that of nitrogen1 and may be consequently discussed in a much shorter space4 ,most soils1 as we have already had occasion to point out1 are better supplied with available ash-plant ingredients than available nitrogen compounds4 ,the quantity of phosphoric acid absorbed by the plant is also less than that of nitrogen2 and lastly1 the different chemical compounds of phosphoric acid occurring in the soil are not nearly so numerous as those of nitrogen4 ,phosphoric acid1 however1 must be regarded as ranking next to nitrogen in its importance as a soil-constituent4 ,occurrence of ,phosphoric ,acid in ,nature4 ,that phosphoric acid is of universal occurrence may be assumed from the fact of the almost universal occurrence of vegetable life on the earth's surface2 for plants are unable to grow without it4 ,while thus of practically universal occurrence1 its amount in most soils is very trifling4 ,as the only source of it in the soil is from the disintegration of the different rocks1 a short description of its occurrence in the mineral kingdom may first be given4 ,mineral ,sources of ,phosphoric ,acid4 ,it was first discovered in the mineral kingdom towards the close of last century2 but we have only of late years ascertained any exact knowledge of its percentage in the different rocks out of which soils are formed4 ,this has been shown in many cases to be very trifling4 ,it most abundantly occurs as apatite1 a mineral consisting of calcium phosphate1 with small quantities of calcium fluoride or calcium chloride4 ,this apatite1 or phosphorite1 is found in certain parts of the world in large masses2 but as a rule1 it only occurs in small quantities in most rocks4 ,it may be stated that the older rocks are1 as a general rule1 richer in it than those of more recent formation2 and ,daubeny has drawn attention to this fact as furnishing a useful guide in estimating the probable richness of a soil in phosphoric acid4 ,the older1 therefore1 a rock is1 the richer it is likely to be in phosphoric acid4 ,apatite and ,phosphorite4 ,of apatite there are a variety of kinds1 which differ in their appearance as well as in their composition4 ,it occurs chiefly in a crystalline form1 and is found sometimes in regular crystals1 but it also occurs in the amorphous form4 ,in colour it may be white1 yellow1 brown1 red1 green1 grey1 or blue4 ,two classes of apatite are found4 ,the first consists of calcium phosphate along with calcium fluoride2 and in other kinds of apatite the calcium fluoride is replaced by calcium chloride4 ,phosphorite is another name for apatite1 but is chiefly applied to impure amorphous apatite4 ,the percentage of phosphate of lime in different kinds of apatite may be stated at from #gj to #ij per cent4 ,it occurs in very large quantities in ,canada1 the ,canadian apatite being very rich in phosphate of lime--#hj to #ij per cent4 ,in many parts of the world it forms portions of mountain-masses1 and is quarried1 crushed1 and used for artificial manurial purposes4 ,further details of its occurrence and chemical composition will be found in the ,appendix4#abc ,coprolites4 ,in many parts of the world round nodules1 largely consisting of phosphate of lime1 have been found1 to which the name coprolites has been given1 on the assumption that they consisted of fossilised animal excrements4 ,these coprolites1 or osteolites as they have also been called1 vary in the percentage of phosphate of lime they contain4 ,sometimes this amounts to #hj per cent1 but as a rule it is very much less4 ,they also in the past have formed an important source of manure1 and will be referred to subsequently4 ,guano4 ,we have1 lastly1 phosphoric acid occurring in large quantities in guano-deposits1 chiefly found on the west coast of ,south ,america4 ,these deposits1 which have been of enormous importance as a source of artificial manure1 are of animal origin1 and will be discussed at considerable length in a chapter specially devoted to the subject2 so that we need do no more than mention them here4 ,phosphoric acid is also found in the form of phosphate of lime in certain rocks as layers and pockets4 ,universal ,occurrence in ,common ,rocks4 ,but while it is thus found in considerable quantities in various parts of the world1 and while no anxiety need thus be felt as to its abundance for artificial manurial purposes1 its occurrence in the common rocks1 which1 as we have already pointed out1 is practically universal1 is in many cases very minute4 ,fownes first identified it in the felspathic rocks in #ahdd2 and since then its percentage in granite1 lava1 trachyte1 basalt1 porphyry1 dolomite1 gneiss1 syenite1 dolerite1 diorite1 and a number of other rocks1 has been determined by numerous investigators4 ,for analyses of these rocks the reader is referred to the ,appendix4#abd ,occurrence in the ,soil4 ,that no soil is actually without phosphoric acid is highly probable1 but in many soils it is present in the merest traces1 and even in fertile soils it is rarely present in quantities over two-tenths of a per cent2 while half that amount may be taken as an average for most fairly fertile soils4 ,this would be about #cejj lb4 per acre1 calculating the soil to a depth of #i inches4 ,in exceptional cases it has been found to the extent of 4#c per cent2 and in the famous ,russian black earth it has been found to amount to 4#f per cent4#abe ,like nitrogen1 it is found in greatest amount in the surface portion of the soil1 but its amount at different depths does not vary to the same extent as we have found to be the case with nitrogen4 ,condition in which ,phosphoric ,acid is present in the ,soil4 ,unlike nitrogen1 phosphoric acid occurs in the soil almost entirely in an insoluble form2 and when applied to the soil in a soluble form1 is speedily converted into an insoluble condition4 ,its most commonly occurring forms are as phosphates of lime1 iron1 and alumina4 ,these facts are of importance to remember1 as they explain why phosphoric acid is not found in drainage-water in any quantity4 ,it also shows how little the risk of loss from drainage is in the application of artificial phosphatic manure to the soil4 ,occurrence in ,plants4 ,the percentage of phosphoric acid in plants1 like other ash-constituents1 is subject to considerable variation1 and depends on a variety of conditions1 such as the state of the plant's development1 nature of soil1 climate1 season1 treatment with manures1 c4 ,all these conditions have a certain influence4 ,the different parts of the plant have been found to contain it in different quantities4 ,the tendency of phosphoric acid is to travel up to the higher portions of the plant with the progress of growth1 and to finally accumulate in the seed4 ,as illustrating this1 it may be mentioned that the inner portion of the stalk of a ripe oat-plant has been found to contain only a seventeenth of the amount of phosphoric acid found in the same portion of the stalk of a young oat-plant4 ,similarly it may be mentioned that1 while the ash of the grain of rye and wheat contains nearly half their weight of phosphoric acid1 the percentage present in the ash of other parts of the plant amounts only to from #e to #af per cent4 ,the percentage of phosphorus is greater in young plants than in mature plants2 it is greater also in quickly developed plants than in slowly developed plants4 ,in the plant1 phosphorus is present chiefly in the albuminoids2 and its absorption from the soil takes place in greatest quantity during the period of maximum growth4 ,in beans and peas an oil containing phosphorus has been found4 ,occurrence in ,animals4 ,that phosphorus in different forms exists in animal tissue is well known4 ,it is found both in the brain and in the nerves1 as well as in nearly all the fluids of the animal body4 ,it is1 however1 in the bones that it is most abundant1 the mineral portion of which is almost entirely made of phosphate of lime1--a fact which renders bones such a valuable artificial manure4 ,altogether1 phosphoric acid occurs in the animal body to the extent of #b4c per cent4 ,there is a point which we shall have occasion to draw the student's attention to further on in discussing the nature of farmyard manure--and that is1 that the urine of the common farm animals is practically devoid of phosphoric acid4 ,sources of ,loss of ,phosphoric ,acid in ,agriculture4 ,as we have already done in the case of nitrogen1 we may now attempt to form some conception of the sources of loss and gain of phosphoric acid in the soil4 ,the sources of loss may be divided into natural and artificial4 ,of natural sources of loss we have only one1 and that is loss by drainage4 ,loss of ,phosphoric ,acid by ,drainage4 ,we have already seen that the condition in which phosphoric acid is present in the soil is as insoluble phosphate4 ,in drainage-water it occurs in mere traces4 ,minute though the amount seems when stated as percentage1 and small as it appears beside the loss 7from the same source7 of nitrogen1 it is yet1 if considered for large areas1 sufficiently striking4 ,thus it has been estimated that in the river ,elbe there is carried off by drainage from the fields of ,bohemia #b-c_/d million pounds 7#abjj tons7 of phosphoric acid annually4 ,this1 it is true1 is a very trifling amount compared with the annual loss of nitrogen from an equal area2 but then it must be remembered1 on the other hand1 the sources of gain to the soil of this ingredient are not so numerous as are those of nitrogen1 the only sources of phosphoric acid being in the manure applied to the soil1 and that coming from the gradual disintegration of phosphatic minerals4 ,artificial ,sources of ,loss4 ,the other sources of loss may be classed under the term artificial1 and are connected with agricultural practice4 ,just as we have seen that in the case of nitrogen enormous quantities of that substance are constantly being removed from the soil in those crops which are consumed off the farm1 so1 too1 enormous quantities of phosphoric acid are being removed in the same way4 ,as illustrating this fact1 it may be mentioned that ,professor ,grandeau has recently estimated that in the entire crops grown in ,france in one year there are about #bih1bjj tons of phosphoric acid2 while the amount returned in the dung of farm animals is only #aeg1bjj1 or only about one-half of what is removed in the crops1 leaving a deficit of #adg1jjj tons to be made good by the addition of artificial phosphatic manures1 if the fertility of the soil is to be maintained4 ,the same authority has calculated that in the bones of the entire farm animals in ,france there is no less a quantity than #gf1hbj tons of phosphoric acid4 ,as an example of how1 in many cases1 the amount of phosphoric acid removed from the farm is very often much greater than that restored1 a case quoted by ,crusius may be cited4 ,this was a farm of #fgj acres 7,saxon7 which had received only farmyard manure1 and from which1 during sixteen years1 #ihe4fg cwt4 of phosphoric acid had been sold off in the crops2 while only #djh4cc cwt4 had been restored in the manure1 leaving a loss of #egg4cd cwt4 ,phosphoric ,acid removed in ,milk4 ,a further source of loss is the phosphoric acid removed in milk4 ,in the total annual yield of milk from one cow there may be from #aa to #ab lb4 of phosphoric acid4 ,loss in ,treatment of ,farmyard ,manure4 ,the risks of loss of phosphoric acid in the treatment of farmyard manure are not so great as in the case of nitrogen4 ,there is1 however1 a considerable risk1 through want of proper precautions1 of the soluble phosphates being washed away by rain4 ,loss in ,sewage4 ,the loss of phosphoric acid incurred by the present method of sewage disposal is not so large as the loss of nitrogen1 inasmuch as the quantity of phosphoric acid contained in human excreta is very much less4 ,roughly speaking1 it may be said to amount to a little less than one-third of the nitrogen lost in this way4 ,sources of ,artificial ,gain of ,phosphoric ,acid4 ,to balance these losses1 we have a practically unlimited supply of mineral phosphates for application as artificial manure1 as well as large quantities of other manures1 many of them already mentioned in connection with nitrogen1 such as bones and guanos of all kinds4 ,quite recently1 also1 a large source of phosphoric acid has been opened up in the basic slag1 a rich phosphatic bye-product obtained in considerable quantity in steel-works from the basic process of steel manufacture4 ,we have also large quantities of phosphoric acid in the imported feeding-stuffs1 for statistics regarding which we would refer our readers to a previous chapter4 ,the question of the actual amount contained in these sources is not of the same interest as in the case of nitrogen1 and need not therefore detain us4 ,we have sufficiently indicated the importance of phosphoric acid in agriculture by the statements above given4 ,all further consideration of phosphoric acid must therefore be deferred to future chapters4 ,,footnotes3 #abc ,see ,appendix1 ,note ,i41 p4 #baj4 #abd ,see ,appendix1 ,note ,,ii41 p4 #baa4 #abe ,these results1 as indeed all soil percentages1 are calculated on the soil in a dry condition4 ,,appendix ,,to ,,chapter ,v ,,note ,i4 7p4 #bja74 ,,composition ,,of ,,apatite 7,voelcker74 7,krageroee1 ,norway47 ,lime #eb4af ,phosphoric acid #da4be ,chlorine #d4aj ,fluorine #a4bc ,oxide of iron #j4bi ,alumina #j4ch ,potash and soda #j4ag ,water #j4db ------ #ajj4jj ,apatite is found in considerable quantities in ,america1 ,germany1 ,france1 ,spain1 ,hungary1 ,norway1 and ,great ,britain4 ,according to ,rose1 apatite is made up of three molecules of tribasic calcium phosphate 7,ca7,,po#d7b71 combined with one molecule of calcium fluoride 7,ca ,f#b7 or one molecule of calcium chloride 7,ca,cl#b7 respectively4 ,the composition of the pure mineral should be-- ,chlorapatite4 ,per cent4 ,calcium phosphate #hi4ch ,calcium chloride #aj4fb ,fluorapatite4 ,calcium phosphate #ib4ca ,calcium fluoride #g4fi ,,note ,,ii4 7p4 #bjc74 ,the following is a list of the commoner rocks in which the percentage of phosphoric acid has been determined4 ,the results are taken from analyses by ,nesbit1 ,schramm1 ,bergemann1 ,rose1 ,deherain1 ,handtke1 ,petersen1 ,nessler1 ,muth1 ,fleischmann1 ,storer1 and others3-- ,per cent4 ,felspar #a4g ,granite #j4ji #j4be #j4eh #j4fh ,lava #a4ba #a4h ,trachyte #j4cj #j4ff ,basalt #j4ej #a4aa ,porphyry #j4bf ,marl #a4de #b4ca #c4h ,calcareous stones #j4jfd #j4agf ,dolomite #a4bd ,lias chalk #a4ci ,gneiss #j4ah #j4gh #a4ea ,syenite #j4aj ,dolerite #j4c #a4a #a4b ,diorite #j4e #j4fi ,,chapter ,,vi4 ,,the ,,position ,,of ,,potash ,,in ,,agriculture4 ,we may1 lastly1 consider the position of potash in agriculture1 the only ash ingredient of the plant1 in addition to phosphoric acid1 which it is as a rule necessary to add as a manure4 ,potash of less ,importance than ,phosphoric ,acid4 ,it is of far less importance than phosphoric acid1 from the fact of its much more abundant occurrence in the soil1 as well as from the fact that under the ordinary conditions of agriculture1 although removed from the soil in considerable quantities by crops1 it finds its way back again in the farmyard manure2 for it has not the same tendency to accumulate in large quantities in the grain or seed as we have seen to be the case with phosphoric acid4 ,on this account straw contains a much greater proportion of potash than phosphoric acid1 and hence farmyard manure may be regarded as fairly rich in potash4 ,occurrence of ,potash4 ,of all sources of potash the ocean must be regarded as the chief4 ,millions and millions of tons are present in a state of solution in the salt water of the ocean4#abf ,like phosphoric acid1 its occurrence in the rocks forming the earth's crust may be said to be practically universal4 ,many of the commonly occurring rocks and minerals are extremely rich in it1 and by their disintegration furnish large quantities to the soil4 ,some of these rocks contain it in such abundance that they have been tried as potash manures2 and were other more valuable sources less available than they actually are1 such a practice might well be recommended4 ,a volcanic rock known as palagonite1 and that most commonly occurring of all potash minerals--viz41 felspar--have both been experimented with in this way with considerable success4 ,felspar and other ,potash ,minerals4 ,that felspar should prove1 when finally ground1 a valuable source of potash1 is not to be wondered at when we remember that some varieties of it contain over #af per cent4 ,it has been calculated that a single cubic foot of this mineral is sufficient to supply an oak-wood1 covering a surface of #bf1iaj square feet1 with potash for a period of no less than five years4#abg ,some idea of the enormous potential fertility of a soil containing felspar1 so far as potash is concerned1 may be obtained from this statement4 ,it must be remembered1 however1 that it is only the orthoclase or potash felspars which contain large quantities of potash--other felspathic rocks1 such as oligoclase and labradorite1 being comparatively poor in it4 ,another commonly occurring mineral which is rich in potash is mica1 which has been found to contain from #e to #ac per cent4 ,from this it follows that rocks which have large amounts of these minerals in their composition--such as granite1 for example1 which often contains #e or #f per cent of potash--form by their disintegration soils rich in this ingredient4 ,stassfurt ,salts4 ,but in addition to the sources of potash already mentioned1 it exists in other forms in the earth's surface4 ,till within recent years it was obtained for commercial purposes from the ashes of plants1 which1 as we shall immediately see1 are extremely rich in this ingredient2 from salt water--this source giving rise to the so-called salt gardens on the coast of ,france2 and from nitre soils in different parts of ,india1 referred to already at considerable length4 ,large mineral deposits1 however1 have been recently discovered in the neighbourhood of ,stassfurt in ,germany1 and have since their discovery supplied all the potash required for manurial and other purposes4 ,in these deposits 7similar ones have also been found at ,kalusz in the ,carpathian ,mountains7 there are no less than five different minerals which contain potash4 ,the form in which it is present is as sulphate or chloride1 so that it is readily available for plants1 and is of altogether very much greater value than the form in which it occurs in the minerals already mentioned--viz41 as an insoluble silicate4 ,of the ,stassfurt potash salts1 the best known as a manure is kainit1 which contains about #cb per cent of sulphate of potash4 ,a list of the other potash minerals1 with the particulars of their composition and the percentage of potash they contain1 will be found in the ,appendix4#abh ,occurrence of ,saltpetre4 ,we have already had occasion1 in ,chapter ,,iv41 when discussing the question of nitrification1 to refer to the occurrence of nitrate of potash in certain soils in ,india1 which have formed a large source of saltpetre used in commerce in the past4 ,occurrence of ,potash in the ,soil4 ,from what has been said regarding the richness in potash of certain commonly occurring minerals1 such as felspar1 it is only natural to infer that most soils must contain large quantities of this substance2 and this is so4 ,the wonder is that potash1 when applied as an artificial manure1 should have such a marked effect in increasing the fertility of the soil1 as is often the case4 ,we must remember1 however1 that although a soil may contain large quantities of potash1 there may be a very small percentage of the whole in an available form for the plant's needs4 ,potash chiefly in insoluble ,condition in ,soils4 ,potash occurs almost entirely in soils in a very insoluble form--viz41 combined with silica as a silicate of potash4 ,it is only by the slow disintegration of potash rocks that the potash they contain is set free for plant uses4 ,when it is applied as an artificial manure1 on the other hand1 it is in a soluble form4 ,in most soils the amount soluble in water probably lies between 4#jja and 4#jji per cent2 that soluble in dilute acid solutions from 4#a to 4#e per cent2 and that insoluble from 4#b to #c4e per cent of the soil4 ,it is highly probable that a certain quantity of potash in the soil may exist in combination with humic and ulmic acids1 forming insoluble potassium humates and ulmates4 ,potash in ,plants4 ,of all the ash ingredients of plants1 potash is the most abundant1 as it forms on an average about #ej per cent of the total ash of plants--about #ij per cent of the alkalies4 ,the ash of plants1 indeed1 was for long the chief source of potash4 ,certain plants remove very large quantities from the soil4 ,of these roots1 potatoes1 the vine1 the tobacco-plant1 and hops may be mentioned as examples4 ,it is present in large quantities in the grain of cereals1 although1 as we have already pointed out1 not to the same proportional extent as phosphoric acid4 ,it is found in the plant's extremities1 such as twigs and new leaves1 in greatest abundance4#abi ,potash in the ,animal ,tissue4 ,it is also found in all parts of the animal body4 ,especially rich in potash salts are the blood corpuscles1 which contain about ten times the amount contained in the serum4 ,it is found in especial abundance in the fleece of sheep1 which may contain more potash than that in the whole body of the sheep4 ,animal urine also contains potash in considerable quantities4 ,sources of ,loss of ,potash4 ,the capacity of the soil to retain soluble potash compounds1 while not equal to its capacity for retaining phosphoric acid1 is yet very much in excess of its capacity for retaining nitrates4 ,the result is1 that potash is only found in comparatively minute traces in drainage water4#acj ,taking the same example as we already cited in illustration of the loss of phosphoric acid1 we find that the amount carried away in the course of a year in the waters of the ,elbe from ,bohemia is #ig1jjj1jjj lb4 7#dc1cjj tons74 ,potash removed in ,crops4 ,the amount of potash removed by the different crops from the soil will be considered in a subsequent chapter4 ,we need only say here that the class of crops which remove the largest quantity are the root crops1 especially mangels4 ,the loss is least in the case of the cereals4 ,the amount of potash contained in the straw of cereals is about three times the amount of that removed in the grain4 ,potash removed in ,milk4 ,lastly1 we may refer to the potash removed in milk1 which1 on an average1 may be taken at #aj lb4 per annum for each cow4 ,potash ,manures4 ,of potash manures the chief are the sulphate and the chloride1 or1 as it is commercially known1 the muriate4 ,the chief source of potash manures are the ,stassfurt deposits already referred to4 ,wood-ashes have also been used in large quantities in the past 7chiefly as a potash manure71 and in some parts of the world are still used4 ,a considerable source of artificial potassic manures is the refuse manufacture of sugar-beet1 such a large industry in ,germany4 ,potash occurs as a constituent of certain other manures1 more valuable for nitrogen and phosphoric acid1 such as guano and dried blood4 ,,footnotes3 #abf ,according to ,boguslawski and ,dittmar1 the total amount of potash calculated as sulphate of potash in salt water equals #aada x #ajab tons4 #abg ,see ,storer's ',agricultural ,chemistry1' vol4 ii4 p4 #bia4 #abh ,see ,appendix1 ,note ,i41 p4 #bbj4 #abi ,see ,appendix1 ,note ,,ii41 p4 #bbj4 #acj ,according to ,way1 different samples of drainage waters were found only to contain from 4#jjjjc to 4#jjjca per cent4 ,,appendix ,,to ,,chapter ,,vi4 ,,note ,i4 7p4 #bae74 ,,amount ,,of ,,potash ,,in ,,different ,,minerals4 ,felspars-- ,percentage of potash4 7a7 ,orthoclase #i4aa #aj4bh #aa4jg #ab4ab #ab4dg #ac4di #ad4ce #ae4ba #af4g 7b7 ,oligoclase #j4ej 7c7 ,labradorite #j4cc ,mica #e4fa #f4bj #g4bc #h4bf #h4ie #i4jj #aj4be #ab4dj #ac4ae ,amphibole #j4be #b4if ,pyroxene #j4cd #b4dh ,leucite #ac4fj #ah4fa ,zeolites #j4cj #i4ce #j4ih #d4ic ,stassfurt potash salts-- ,per cent4 7a7 ,polyhallite1 potassium sulphate #bh 7b7 ,karnallite 7,k,cl4,mg,cl#bf;,h#bj71 potassium chloride #bd to #bg 7c7 ,sylvin1 pure potassium chloride4 7d7 ,kainit 7,k#b,,so#d,mg,s,o#d,mg,cl#bf;,h#b,o71 potassium sulphate #cb 7e7 ,schoenite 7,k#b,,so#d1 ,mg,s,o#d1 #f;,h#b,o71 pure potassium magnesium sulphate4 ,,note ,,ii4 7p4 #bag74 ,the quantity of potash obtainable from various plants in the manufacture of potashes on a large scale is illustrated by the following statements4 #ajjj lb4 of the following vegetative products yield the following quantities of potashes3-- lb4 ,old spruce-wood #a_/b ,old poplar-wood #c_/d ,old oak-wood #a-a_/b ,corn-stalks #ag-a_/b ,bean-stalks #bj ,grape-vine twigs #dj 7,storer1 ',agricultural ,chemistry1' vol4 ii4 p4 #ajh47 ,,part ,,iii4 ,,manures ,,chapter ,,vii4 ,,farmyard ,,manure ,farmyard manure is the oldest1 and is still undoubtedly the most popular1 of all manures4 ,it has stood the test of long experience1 and has proved its position as one of the most important of all our fertilisers4 ,it is highly desirable1 therefore1 to make a somewhat detailed examination of its composition1 and to see on what the variation in this depends2 and1 finally1 to examine into the mode of its action as a manure4 ,that it should prove a valuable manure is scarcely to be wondered at1 as it is originally formed from vegetable substance1 and as it therefore contains all the elements present in the plant itself4 ,its composition is very variable1 and probably no two samples would yield exactly similar analyses4 ,in this fact lies one of the chief difficulties of the treatment of the subject1 and all statements made in the following pages as to its chemical composition must be taken as only approximate4 ,we may divide its constituents into three classes4 #a4 ,that portion due to solid excreta4 #b4 ,the liquid portion1 largely made up of dilute urine4 #c4 ,the straw1 or other material1 which is used as litter4 ,the composition of the manure will vary according to the proportion in which these three substances are present1 as well as according to the composition of the substances themselves4 ,it will consequently tend to a clearer apprehension of the subject if we first examine briefly the chemical composition of the solid excreta and urine of the farm animals4 #a4 ,solid ,excreta4 ,the manurial value of the solid excreta of animals--i4e41 the proportion they contain of nitrogen1 phosphoric acid1 and potash--depends on a variety of conditions4 ,the solid excreta of horses1 sheep1 cows1 and pigs1 are well known to possess different properties1 as well as to vary in their composition4 ,what1 however1 has a still greater influence is the nature of the food4 ,this is owing to the fact that the solid excreta are made up of undigested food4 ,we can scarcely expect the same quality of solid excreta from an animal fed on poor diet as from an animal fed on very much richer diet4 ,again1 the percentage of the food voided in the solid excreta varies in the case of different animals4#aca ,another consideration which enters into the question is the age1 as well as the treatment1 of the animal4 ,a young animal1 during the period of its growth1 absorbs from its food into its system a larger quantity of the three fertilising substances1 nitrogen1 phosphoric acid1 and potash1 than is the case with an adult animal whose weight is neither increasing nor diminishing4 ,a working horse1 similarly1 will return more of the nitrogen1 phosphates1 and potash in its dung than one not at work and which is permitted to gain in weight4 ,the nature of the composition of the solid excreta1 therefore1 will depend on the nature of the food1 age1 breed1 condition1 and treatment of the animal4 ,let us now investigate shortly the influence of the above considerations4 ,the solid excrements of the common farm animals are generally distinguished from one another according to the rate at which they decompose or ferment on keeping4 ,thus horse-dung is generally known as a hot dung2 while cow-dung1 on the other hand1 is known as cool4 ,why this should be so is not absolutely clear4 ,probably it is owing to the fact that the former contains less water1 as well as to the fact 7and this probably has more to do with it7 that it contains a larger percentage of fertilising matter1 especially nitrogen1 thus affording conditions more favourable for rapid fermentation than in the case of the more moist and less rich cow-dung4 ,the composition of the solid excreta of various animals1 as we have just said1 varies with the nature of their food2 so that it is impossible to take any analyses as absolutely representing its composition4 ,it may be interesting1 however1 to compare the analyses of samples of horse-dung with those of some other of the commoner farm animals1 with a view to obtaining an approximate idea of this difference4 ,stoeckhardt has found that in #ajjj lb4 of the fresh solid excreta of the animals below mentioned1 there were the following amounts of nitrogen1 phosphoric acid1 and alkalies3-- ---------------------------------------- ------------------------------ ,,phosphoric ,,nitrogen4 ,,acid4 ,,alkalies4 ,,water4 ---------------------------------- ,reduced ,reduced ,reduced to to to ---------------------------------------- -------------------------- lb4 per lb4 per lb4 per lb4 per cent4 cent4 cent4 cent4 ,horses 7winter food7 #gfj #gf #e 4#ej #c-a_/b 4#ce #c 4#cj ,cows 7winter food7 #hdj #hd #c 4#cj #b-a_/b 4#be #a 4#aj ,swine 7winter food7 #hjj #hj #f 4#fj #d-a_/b 4#de #e 4#ej ,sheep 7#b lb4 hay per diem7 #ehj #eh #g-a_/b 4#ge #f 4#f #c 4#cj ---------------------------------------- -------------------------- ,from the above table it will be seen that the sheep's dung contains the least percentage of water1 and is richer in nitrogen and phosphoric acid than any of the other three4 ,the percentage of alkalies1 of which the most important is potash1 is1 however1 not so large4 ,this may be accounted for by the interesting and well-known fact that a large percentage of potash is to be found in the wool of sheep4#acb ,the solid excrement of the sheep is1 therefore1 weight for weight1 the most valuable as a manure1 as it contains more nitrogen and phosphates than the others1 and at the same time is much drier4 ,if1 however1 we compare the composition of the solid excreta in a dry state1 we shall find that the following are the results 7basing our calculation on ,stoeckhardt's analyses73-- ,nitrogen1 ,phosphoric acid1 ,alkalies1 per cent4 per cent4 per cent4 ,horse #b4jh #a4de #a4be ,cow #a4hg #a4ef #j4fb ,pig #c4jj #b4be #b4ej ,sheep #a4gh #a4db #j4ga ,it will be seen from the above that the dry substance of the solid excreta of the pig is richest in fertilising substances4 ,too much stress1 however1 as has already been pointed out1 must not be put on any single analysis1 as so much depends on various conditions1 especially the food4#acc ,the most reliable method of studying this question1 therefore1 is to study it in its relation to the food consumed4 ,wolff has calculated from numerous investigations that1 with regard to the amount of solid excreta produced by the food1 the following percentage of organic matter1 nitrogen1 and mineral substances1 originally present in the dry matter of the food1 is voided in the dung3-- ,cow4 ,ox4 ,sheep4 ,horse4 ,average4 ,organic matter #ci4e #db4e #dd4j #dd4a #db4e ,nitrogen #dg4e #cc4i #df4g #cb4d #dj4a ,mineral substances #ec4i #fd4f #eg4i #fb4e #ei4g ,there is one fact to be borne in mind in estimating the manurial value of the dung of different animals--viz41 that the quantity of dung voided by one animal is much greater than that voided by another4 ,thus the amount voided by the cow1 for example1 is much greater than that voided by the horse2 so that1 in this way1 the inferior quality of the former is1 to some extent1 compensated for by its greater quantity4 #b4 ,urine4 ,the solid excreta possess1 however1 very much less manurial value than the urine4 ,the former1 as already stated1 are undigested food-substances3 any fertilising matters which they contain are such as have failed to be digested or absorbed into the animal system4 ,the urine1 on the other hand1 contains those fertilising substances which have been digested4 ,the amount of nitrogen and mineral matter1 however1 in the urine1 does not represent necessarily the total amount of these substances4 ,thus1 in the case of a growing or fattening animal1 there is always a certain amount of these substances being absorbed to build up the animal tissue and put on flesh4 ,in this respect it will be seen that the composition of urine will vary in the same way as that of the dung4 ,in the case of the urine1 however1 there is a compensating influence to be taken into account4 ,urine is a waste product1 and there is more waste in a young than in an adult animal4 ,another very important condition which determines the composition of urine is the nature of the food1 especially the quantity of water drunk4 ,this1 of course1 is obvious3 the more water drunk1 the poorer must the composition of the urine be4 ,but here again1 as in the case of the dung1 this is largely compensated for by the total quantity voided--the more dilute the urine1 the larger will its quantity be2 so that the inferior quality is in this way made up for by its increased quantity4 ,keeping in mind1 then1 the fact we have just stated--viz41 that the composition of urine will vary according to different conditions--we may obtain an approximate idea of what its composition is from the following results of analyses by ,stoeckhardt4 ,in #ajjj parts the following quantities of water1 nitrogen1 phosphoric acid1 and alkalies were found to be present4 ,from the following table it will be seen that the urine of swine 7containing #ig per cent of water7 is much poorer in nitrogen and alkalies than is the case with the urine of the sheep1 horse1 or cow4#acd ,while this is the case1 the amount of phosphoric acid it contains is greater than that contained in the sheep's urine4 ---------------------------------------- ---------------------------- ,phosphoric ,water4 ,nitrogen4 ,acid4 ,alkalies4 ---------------------------------------- ---- ,per ,per ,per ,per ,per ,per ,per ,per #ajjj cent4 #ajjj cent4 #ajjj cent4 #ajjj cent4 parts4 parts4 parts4 parts4 ---------------------------------------- ----------------------- ,sheep 7#b lb4 hay #hfe #hf4e #ad #a4d 4#e 4#jej #bj #b4j per diem7 ,swine 7winter food7 #ige #ig4e #c 4#c #a4be 4#abe #b 4#b ,horses 7hay and #hij #hi4j #ab #a4b - - #ae #a4e oats7 ,cows 7hay and #ibj #ib4j #h 4#h - - #ad #a4d potatoes7 ---------------------------------------- ----------------------- ,phosphoric acid is present in the urine of the farm animals in the most minute traces3 practically1 it may be considered to be wanting in the urine of the horse and the cow1 and is present only in small quantities in sheep's urine4 ,the pig's urine1 indeed1 contains it in larger quantities2 but the percentage is still so small as to justify the statement that the urine of the common farm animals is not a complete manure1 and must be supplemented by phosphates1 if it is to be used alone4 ,the incomplete nature of urine as a manure constitutes a strong argument in favour of its being applied along with the solid excreta1 which contain1 as we have seen1 considerable quantities of phosphoric acid4 ,it is on this account that the drainings of rotten manure-heaps are more valuable1 from a manurial point of view1 than urine itself1 since these contain the soluble portion of the phosphates in the solid excreta4#ace ,the urine of all animals1 however1 is not equally poor in phosphates4 ,in the case of flesh-eating animals1 such as the dog1 the urine is found to contain them in considerable quantities4 ,the above tables show that the most valuable urine1 weight for weight1 is that of the sheep1 as it contains the largest amount of alkalies 7including potash7 and nitrogen2 that the urine of the horse comes next2 then that of the cow2 while1 as has already been pointed out1 that of the pig is the poorest4 ,in order to make our survey of the composition of urine uniform with that of the dung1 let us see how the urine of the common farm animals compares in the matter of the composition of its dry substance4 ,the following results 7basing our calculations on ,stoeckhardt's figures1 previously given7 show this3-- ,nitrogen1 ,phosphoric acid1 ,alkalies1 per cent4 per cent4 per cent4 ,pig #ab4j #e #h ,horse #aj4i trace #ac4f ,sheep #aj4d #c4g #ad4i ,cow #aj4j trace #ag4e ,from these figures we see that the dry substance of the urine of the pig is richest in nitrogen and phosphoric acid1 but poorest in alkalies1 of the four common farm animals2 that of the horse comes next in the amount of nitrogen it contains1 but that1 on the whole1 there is very little difference between the horse1 cow1 and sheep in this respect4#acf ,as in the case of the dung1 this subject is best studied in relation to the food consumed4 ,we are again indebted to ,wolff's investigations for valuable information on this point4 ,he has found that the following percentages of organic matter1 nitrogen1 and mineral substances1 originally present in the dry matter of the food1 are voided in the urine3-- ,cow4 ,ox4 ,sheep4 ,horse4 ,average ,organic matter #d4j #d4d #b4j #c4c #c4d ,nitrogen #ca4j #ed4h #db4c #fj4g #dg4b ,mineral substances #dc4a #cd4c #da4j #cg4e #ci4jacg ,we have now considered briefly the composition of the solid excrements and urine of the common farm animals1 and have also enumerated some of the principal causes of the variation in their composition4 ,the solid excreta consist1 as we have seen1 of undigested food1 while the urine contains the manurial ingredients of the food which have been digested by the animal system4#ach ,the latter is1 weight for weight1 as a rule1 very much more valuable as a manure than the former4 ,from the table given in the ,appendix#aci it will be seen that the proportions of the nitrogen and ash-constituents originally present in the food consumed1 which are voided in the excrements1 vary with different circumstances4 ,wolff1 in summarising his results1 points out that1 as a rule1 the solid and liquid excrements will contain about #df per cent of the organic matter1 #hg4c of the nitrogen1 and #ih4g of mineral matter2 while the experiments of ,lawes and ,gilbert at ,rothamsted show that1 with fattening oxen and sheep and with horses1 more than #ie per cent of the nitrogen and #if per cent or more of the ash-constituents are voided in the manure4 ,the pig retains a larger proportion of the nitrogen--about #he per cent appearing in the manure--while in the milking-cow only about #ge per cent is returned in the excrements4 ,generally speaking1 we may say that the nitrogen originally present in the food suffers very little loss in passing through the animal system1 and that1 practically speaking1 the ash-constituents suffer no loss whatever4 ,as to the distribution of the manurial ingredients1 much will depend on the nature of the food4 ,almost invariably more than a half of the total nitrogen excreted will be found in the urine1 in many cases very much more4#adj ,of the mineral constituents1 about a third on the average may be said to be excreted in the urine4 ,of this mineral matter it may be noted that nearly all the alkalies 7potash and soda71 or about #ih per cent1 are found in the urine4 ,of phosphoric acid and lime1 on the other hand1 there are the merest traces in the urine4 ,horse-urine1 however1 is an exception with regard to lime1 as it contains about #fj per cent of the lime consumed in the food4 ,for information on the subject of pig-manure the reader is referred to ,appendix1 ,note ,v4#ada ,before passing from this part of the subject1 it may be desirable to place before our readers the composition of the dung and urine taken together1 so that we may be able to form some idea of their relative value1 weight for weight4 ,as the nitrogen constitutes by far the most valuable portion of the manurial ingredients1 it will be sufficient if we compare them as to their percentage of this ingredient4 ,water1 ,nitrogen1 ,calculated on per cent4 per cent4 dry substance1 ,analyses by per cent4 ,sheep #fg 4#ia #b4g ,juergensen4 ,horse #gf 4#fe #b4g ,boussingault4 ,pig #hb 4#fa #c4d ,boussingault4 ,cow #hf 4#cf #b4f ,boussingault4 ,from these figures we see that1 in their natural condition1 the excreta of the sheep are the most valuable2 those of the horse and pig coming next2 while those of the cow are the poorest1 containing one-third as much nitrogen as those of the sheep1 and one-half as much as those of the horse and pig4 ,this difference1 however1 is due almost entirely to the different percentage of water the excreta of the various animals contain in their natural state2 for in the dry state they are seen to contain1 with the single exception of the pig1 practically the same amount4 ,in conclusion1 then1 the important points to be noticed are-- #a4 ,that in the passage of the food through the system of the common farm animals1 only a very small percentage of the fertilising substances1 nitrogen1 phosphoric acid1 and potash1 is assimilated and retained in the animal body2 and that1 therefore1 theoretically at least1 the excreta should contain nearly the same amount of fertilising matter as the food originally did4 #b4 ,that even in the case of a fattening animal1 the loss of fertilising matter sustained by the food in passing through the system is not great4 #c4 ,that with regard to the total amount of solid excreta and urine voided1 the latter contains1 as a rule1 more nitrogen than the former2 the nitrogen in the urine1 further1 being more valuable1 as it is in a soluble condition4 #d4 ,that as regards the distribution of the ash-constituents1 lime1 phosphoric acid1 and magnesia are almost entirely found in the solid excrements2 while the urine contains nearly all the potash4 #e4 ,that the best results can be expected only when the liquid and solid excreta are used together as a manure4 ,as the composition of the manure depends so largely on the nature of the food1 a table will be found in the ,appendix1 ,note ,,vi41#adb containing the manurial composition of some of the commoner feeding-stuffs4 #c4 ,litter4 ,we have now to consider the third constituent of farmyard manure--viz41 the litter1 which generally consists of straw4 ,the uses of the litter1 in addition to providing a dry and comfortable bed for the animal1 may be briefly summed up as follows3-- #a4 ,to absorb and retain the liquid portion of the excreta4 #b4 ,to increase the quantity of the manure1 and thus secure its more equal distribution when applied to the field than could otherwise be done4 #c4 ,to add to its value as a manure1 both physically and chemically4 #d4 ,to retard and regulate the decomposition of the excreta4 ,of course litter also performs a very useful function sanitarily1 inasmuch as it serves to keep the stall or byre fresher and cleaner1 and more free from noxious gases1 which it absorbs1 than would otherwise be the case4 ,straw is almost universally used for this purpose4 ,besides being one of the bye-products of the farm1 it is admirably suited in many ways1 both owing to its peculiar shape--its tubular structure being excellently adapted for this purpose--as well as on account of its composition1 being largely composed of cellulose1 a very absorptive substance4 ,straw thus possesses considerable absorptive power4 ,in manurial ingredients it is not very rich2 for1 of the various parts of the ripened plant1 straw contains the least percentage of nitrogen and phosphates4 ,this is due to the fact that1 as the straw ripens1 a considerable proportion of these ingredients passes up from the stalk to the seeds1 where they are retained4 ,generally speaking1 straw may be said to contain not more than a half per cent of nitrogen--i4e41 #aa4b lb4 per ton4 ,its percentage of nitrogen varies1 of course2 the recorded analyses#adc for wheat-straw ranging from 4#bb to 4#ha per cent1 or furnishing an average of 4#dh per cent--i4e41 #aj4ge lb4 per ton4 ,barley-straw is somewhat richer in nitrogen1 the recorded analyses ranging from 4#da to 4#he per cent1 or giving an average of 4#eg per cent--i4e41 #ab4gf lb4 per ton2 while oat-straw is the richest of the commoner straws1 ranging from 4#cb to #a4ab per cent1 an average of 4#gb per cent--i4e41 #af4ab lb per ton4 ,of mineral matter1 however1 straw contains a very much larger percentage1 proportionally1 than of nitrogen2 for1 with the exception of phosphates1 there is a considerable quantity of inorganic fertilising matter1 in the shape of potash1 lime1 c41 present in ,composition of ,straw4#add ---------------------------------------- ------------------------ ,ash4 ,composition of ,ash4 -------------------------------------- ,lb4 per ton4 ,lb4 ---------------------- ,number ,per per ,potash4,phosphoric,lime4 of cent4 ton4 ,acid ,analyses ---------------------------------------- --------------------- ,wheat 7winter7 #e4ed #abd4ji #ah4fa #e4je #g4ah #h ,wheat 7summer7 #e4ad #aae4ac #be4gf #f4dg #g4ab #f ,rye 7winter7 #e4cc #aai4ci #bj4fa #e4hi #i4gc #h ,rye 7summer7 #f4ad #acg4ec #db4da #f4gc #aj4ec #a ,barley #d4ij #aji4gf #bf4hc #e4ge #h4gc #h ,oats #e4ji #aad4ja #bf4bb #d4ag #i4ab #d ---------------------------------------- --------------------- it4 ,of total ash ingredients1 on an average1 there are generally about #e per cent--or #aab lb4 per ton4 ,the largest percentage of the fertilising matter in this #e per cent is potash1 which varies in the ashes of the straws of the commoner crops from #cj to #ae per cent4 ,the above table will show the variation in composition of the straws of some of the commoner farm crops1 and may be valuable for purposes of reference4 ,the crops are wheat 7winter and summer71 barley1 oats1 and rye 7winter and summer71 and the amount is also calculated in lb4 per ton4 ,the results represent the average of a number of analyses4#ade ,from the table it will be seen that the percentage of phosphates is1 as has already been noticed1 very small4 ,but while straw is well adapted for the purposes for which litter is used1 it is not the only substance4 ,its almost exclusive use as litter is largely owing to the fact that it is a bye-product of the farm4 ,loam as ,litter4--,generally speaking1 any substance which has great absorptive as well as retentive powers for nitrogen and the soluble fertilising matters present in farmyard manure1 and whose price is nominal1 is well suited for acting as litter4 ,ordinary loamy soil possesses the above qualifications1 and is1 besides1 a substance to be had for nothing1 and1 under certain circumstances and in certain countries1 is actually used for this purpose1 often along with straw4 ,a great objection against loam1 however1 is that it forms a dirty litter4 ,moreover1 it possesses a very small percentage of fertilising matter4 ,the tendency1 consequently1 in using ordinary loam1 would be to dilute the manure too much1 besides retarding fermentation to an undesirable extent4 ,except1 therefore1 under very exceptional circumstances1 loam is not to be regarded as a good litter4 ,peat as ,litter4--,some kinds of soil1 however1 are well suited for this purpose4 ,of these1 the best are those rich in organic matter1 the so-called peaty soils4 ,peat1 when dried and freed from any earthy matter1 forms an excellent absorbent of the liquid portion of the manure1 surpassing in this respect straw itself4 ,it is1 further1 generally very much richer in nitrogen--some peats having been found to contain between #d and #e per cent of nitrogen4 ,in some thirty samples of peat analysed by ,professor ,s4 ,w4 ,johnson1 the percentage of nitrogen varied from 4#d to #b4i1 giving an average of #a4e per cent4 ,while it has a very great capacity for absorbing liquids1 it possesses in an unequalled degree the power of retaining the soluble nitrogen compounds4 ,this is undoubtedly one of the most important properties which recommend peat for the purposes of litter4#adf ,some interesting experiments on the value of peat-moss as a litter have been recently carried out by ,dr ,bernard ,dyer4#adg ,from these experiments ,mr ,dyer has found that both its liquid-absorbing and liquid-retaining powers are very much greater than those of straw4 ,while straw was only able to absorb three times its weight of water1 peat-moss was found to absorb nearly ten times its weight4 ,with regard to its water-retaining power1 this was also found to be in excess of that of straw4 ,both these properties are1 it need scarcely be pointed out1 of very great value in a litter4 ,another point of interest in these experiments was the respective amounts of nitrogen absorbed and retained by the peat-moss and the straw4 ,it was found that1 in this respect1 the peat-moss had again an advantage over the straw4 ,lastly1 the manure produced by the peat-moss was shown to be richer in fertilising matter than that produced by the use of straw4#adh ,these experiments are interesting as demonstrating the fact that in peat-moss we have a substance which is capable of acting as an excellent substitute for the more costly straw1 and which might increasingly be used as a fodder with great benefit to the farmer4 ,another substance which has been suggested as an excellent litter is the common bracken-fern4 ,according to some analyses made by ,mr ,john ,hughes1 the bracken1 especially if cut in a young state1 is a substance of considerable manurial value4 ,when dried1 it is very much richer in nitrogen1 potash1 and lime than straw4 ,its absorbent properties1 however1 are probably not so great4 ,where it can easily and cheaply be had1 as in many parts of ,scotland and ,ireland1 it might well be used for littering purposes4#adi ,dried leaves have also been used as a litter4 ,autumn leaves1 however1 contain a very small percentage of fertilising matter4 ,this is due to the fact that the most of their potash1 phosphoric acid1 and nitrogen pass into the body of the trees at the approach of winter4 ,according to ,professor ,storer1 dried leaves only contain from 4#a to 4#e per cent potash14#jjf to 4#c per cent phosphoric acid1 and about 4#ge per cent of nitrogen4 ,leaves1 however1 besides being poor in manurial ingredients1 make a bad litter1 as they ferment but slowly4 ,there is in this fermentation a large quantity of cold sour humic acid formed1 which seriously impairs the value of the manure4#aej ,having now considered the composition of the three separate ingredients of farmyard manure--viz41 the dung or solid excreta1 the urine1 and the litter--we are in a position to consider the composition of farmyard manure4 ,in this connection it will be well to consider separately the manures produced by the different farm animals4 #a4 ,horse-manure4 ,the composition of horse-manure is perhaps the most uniform of all the manures produced by the different farm animals4 ,this is due to the fact that the food of the horse is generally of the same kind1 consisting of oats1 hay1 and straw4 ,the total excrements voided by a horse in a day have been calculated1 according to the average of experiments by ,boussingault and ,hofmeister1 at #bh4aa lb41 of which only #f4cg lb4 consisted of dry matter4#aea ,these #bh4aa lb4 contained 4#ah lb4 of nitrogen and 4#ib lb4 of mineral matter4 ,the amount of straw necessary to absorb this amount of excrement may be stated at from #d to #f lb4 ,the amounts of nitrogen and mineral matter in #d lb4 of straw are 4#ja and 4#bc lb4 respectively4 ,the total amount of nitrogen and ash1 therefore1 in the farmyard manure produced by a horse in one day1 would be 4#ai lb4 nitrogen and #a4ae lb4 mineral matter2 or1 if we take the larger quantity of straw1 somewhat more4 ,taking these figures1 we find that the amount of manure produced by a horse in a year will be from #aa1gbj to #ab1dej lb4 7i4e41 from #e-a_/d to #e-a_/b tons71#aeb containing from #fi to #gc lb4 nitrogen1 and from #dbj to #dfj lb4 mineral matter4#aec ,a word or two may be of value regarding the treatment in the stable of horse-manure4 ,the great object to be aimed at is the prevention of loss of valuable fertilising constituents4 ,this loss may be due to two causes4 ,it may be1 in the first place1 caused by drainage of the soluble matter of the manure2 or secondly1 it may be due to volatilisation of the volatile constituents4 ,the first of these two sources of loss depends on the precautions taken in the way of providing a proper impervious flooring to the stable4 ,this source of loss is extremely difficult to prevent1 inasmuch as nearly all materials used for flooring absorb a certain percentage of urine4 ,the judicious use of litter1 however1 will minimise this loss to within a trifling extent4 ,dr ,heiden states that the amount of straw used as litter for the horse in ,germany is from #d to #f lb4 per day4 ,the quantity should be regulated according to the percentage of water the excreta contain2 the more watery excreta requiring naturally a larger quantity of litter4 ,the most eminent authorities on this subject recommend that the amount of litter should equal one-fourth of the food in its natural state1 or about one-third of its dry substance4 ,the second source of loss1 which is due to volatilisation of the volatile ingredients1 may be largely prevented by the use of certain preservatives4 ,horse-dung being1 comparatively speaking1 of a dry nature1 it is extremely difficult to effect its thorough mixture with the litter4 ,for this reason the manure formed from horse excreta is particularly liable to rapid fermentation4#aed ,in the process of fermentation1 as will be seen more in detail further on1 the nitrogen is converted into carbonate of ammonia4 ,as nitrogen in this form is of an extremely volatile nature1 the risks of loss from this source are considerable4 ,as illustrating this fact1 it may be mentioned that ,boussingault has found by experiment that the total percentage of nitrogen contained by fresh horse-manure might be reduced in the process of fermentation to one-half of its original amount by loss from this source4 ,the preservatives used to prevent this volatilisation are technically known as fixers4 ,this they do by chemically combining with the volatile ammonia and forming non-volatile compounds with it4 ,of the acid fixers1 hydrochloric and sulphuric acids have been recommended4 ,the former1 however1 is not well suited for this purpose4 ,it is a strongly fuming acid1 and when brought into contact with ammonia forms dense white fumes4 ,the use of sulphuric acid is not open to this objection4 ,sulphate of ammonia1 the salt formed in this case1 is one of the most stable 7or least volatile7 of the compounds of ammonia4 ,if used1 it should be largely diluted with water1 and the whole mixed with sand4 ,such a mixture1 when sprinkled over the stable-floor in even very small quantities1 has been found to effectually prevent any loss of the volatile carbonate of ammonia4 ,it is not1 however1 on the whole advisable to use an acid substance as a fixer1 since such a substance may act deleteriously on the horses' hoofs4 ,such substances as gypsum1 copperas1 and sulphate of magnesia1 while equally efficient1 are not open to this objection4 ,the above-mentioned substances owe their efficacy to the fact that they are compounds of sulphuric acid1 which1 by combining with the volatile ammonia and forming sulphate of ammonia1 prevent its escape4 ,gypsum1 or sulphate of lime1 although1 comparatively speaking1 an insoluble substance1 when brought in contact with carbonate of ammonia has been proved to effect the conversion of the ammonia into sulphate of ammonia4 ,it is also believed to retard the decomposition of the manure4#aee ,copperas1 or ferrous sulphate1 while a soluble salt1 and while thus acting in a more speedy manner in fixing the ammonia1 is not so well suited1 owing to the hurtful influence it is well known to possess on plant-life4 ,it is only right to remember that there may be circumstances in which copperas may1 in small quantities1 act even beneficially as a manure1 as ,griffiths' experiments would seem to indicate4 ,the above objection1 however1 cannot be urged against sulphate of magnesia4 ,in addition to fixing the ammonia1 sulphate of magnesia may very probably fix the soluble phosphoric acid4 ,kainit1 which consists of a mixture of sulphates and chlorides of potassium and magnesium1 has also been suggested for this purpose4 ,by using such a fixer1 the value of the resulting manure would be much enhanced4 ,in conclusion1 it must be remembered that all the above-named fixers act very much in the same way--viz41 by converting the volatile carbonate of ammonia into sulphate of ammonia4#aef #b4 ,cow-manure4 ,the composition of the manure formed from the excrementitious matter of the cow is very much less constant than is the case in the horse-manure4 ,an average statement of that composition is therefore very much more difficult to obtain4 ,the number of analyses available for the purpose of forming this average is1 however1 very large4 ,the manure produced by cows contains a large percentage of water4 ,this is due to the large quantity of water they drink4 ,it has been estimated that milch-cows drink along with their winter food1 for every pound of dry substance1 #d lb4 of water1 and in summer about #f lb4 ,according to some experiments by ,boussingault1 the excrements of a cow in a day amounted to #gc4bc lb41 of which only #i4ib lb4 were dry matter4#aeg ,these excrements contained 4#bef lb4 of nitrogen and #a4gbe lb4 of mineral matter4 ,the amount of straw necessary to use as litter for this amount of excrements may be taken at #f to #aj lb4 ,the manure1 therefore1 formed by a cow per day1 would contain from 4#bgd to 4#bhf lb4 of nitrogen1 and from #b4jdf to #b4bgh lb4 of mineral matter4 ,in a year this would amount to from #ajj to #ajd4d lb4 of nitrogen1 and from #gdf4h lb4 to #hca4e lb4 of mineral matter2 or from #f cwt4 #ge lb4 to #g cwt4 #dg lb4 ,cow-dung is1 owing to its more watery nature and poorer quality1 very much slower in its fermentation than horse-dung4 ,when applied alone1 cow-manure is very slow in its action1 and makes its influence felt for at least three or four years4 ,it is difficult to spread it evenly over the soil1 owing to the fact that1 when somewhat dried1 it has a tendency to form hard masses1 which1 when buried in the soil1 may resist decomposition for a very long period4 ,the cause of this is due to the presence of a considerable amount of mucilaginous and resinous matter in the solid excreta1 which prevents the entrance of moisture and air into the centre of the mass4 ,this tendency of cow-manure to resist decomposition will be greatly lessened in the case of the excrements of a cow richly fed4 ,the risks of loss of volatile ammonia are1 therefore1 in its case not so great as we have seen them to be in the case of the hot horse-dung4 ,notwithstanding this fact1 much of what has been said on the use of preservatives for horse-manure may be also applied to the cow-dung4 ,this is owing to the fact that the dung is allowed to accumulate in the court for some time4 ,the amount of straw it is advisable to use as litter varies1 as has been said1 from #f to #aj lb4 per day4 ,the best method of calculating this amount1 according to ,dr ,heiden1 is by taking one-third of the total weight of the dry substance of the food4 ,the above authority also recommends that the straw is best applied in blocks of about one foot in length2 and this for the following reasons3-- #a4 ,the strewing of it is more convenient4 #b4 ,the absorption of the fluid portion is more complete4 #c4 ,the cleaning out of the manure from the byre is easier4 #d4 ,the manure is more easily distributed when applied to the field4 ,among the advantages incidental to allowing the manure to accumulate in the court may be mentioned the following3-- #a4 ,the more thorough absorption of the urine by the straw1 and1 consequently1 the more uniform mixture which will be thus effected of the more valuable urine with the less valuable solid excreta4 #b4 ,a certain retardation of decomposition effected by the treading under foot of the manure4 #c4 ,the protection of the manure from rain and wind1 and the securing of a uniform temperature4 ,against those advantages must be placed the risk of seriously affecting the health of the animal4 ,although this is a point of very great importance1 it scarcely falls within the scope of this work4 ,it may be pointed out1 however1 that the judicious use of some of the chemical fixers previously referred to may do much to keep the air of the byre or court free of noxious gases4#aeh #c4 ,pig-manure4 ,the food of the pig is so very variable in its character that it is wellnigh impossible to obtain anything like an average analysis of its excrements4 ,when the food of the pig is rich1 then the manure may be quite equal in quality to the other manures4 ,according to ,boussingault1 the total amount of excrements1 on an average1 voided by a pig in twenty-four hours is about #h4cb lb41 of which #a4e lb4 is dry matter4#aei ,the amount of nitrogen these excrements contain is only 4#je lb41 and of mineral ingredients 4#cac lb4 ,if we take the amount of straw most suitable for absorbing this quantity of excrementitious matter at from #d to #h lb41 then we shall find that the manure produced by a pig will contain from 4#jf to 4#jgd lb4 nitrogen and 4#ede to 4#ggb lb4 mineral matter4 ,these quantities1 calculated for a year1 give from #bb to #bg lb4 of nitrogen1 and from #a cwt4 #hg lb4 to #b cwt4 #eg lb4 of mineral matter4 ,that is about as much nitrogen as would be contained in #a-a_/d to #a-a_/b cwt4 of nitrate of soda 7#ie per cent purity72 or from slightly less than #a cwt4 to slightly over #a cwt4 of sulphate of ammonia 7#ig per cent purity74 ,as has already been pointed out1 the excrements of the pig are1 as a rule1 very poor in nitrogen4 ,this accounts for the fact that pig-manure is a cold manure1 slow in fermenting4#afj #d4 ,sheep-manure4 ,the dung and the urine of the sheep1 as we have already seen1 are1 weight for weight1 the most valuable of any of the common farm animals4 ,the total weight of the excrements voided by a sheep in a day may be taken1 on an average1#afa at #c4gh lb41 of which 4#ig lb4 is dry matter4 ,these excrements contain 4#jch lb4 of nitrogen and 4#bbc lb4 mineral matter4 ,taking the amount of straw most suitable for absorbing this quantity of excrementitious matter at three-fifths of a pound1 then the manure produced by a sheep in a day will contain 4#jdbi lb4 nitrogen and 4#bfd lb4 mineral matter4 ,that is1 in a year the quantities of nitrogen and mineral matter in the manure produced by a sheep would be #ae4ff lb4 of nitrogen and #if4cf lb4 of mineral matter4 ,from its richness in nitrogen1 and from its dry condition1 sheep-dung is peculiarly liable to ferment4 ,while richer in fertilising substances than horse-manure1 it is not so rapid in its fermentation4 ,this is due to the harder and more compact physical character of the solid excreta4 ,the risks of loss of volatile ammonia are1 in its case1 exceptionally great4 ,the use of artificial fixers is therefore to be strongly recommended4#afb ,fermentation of ,farmyard ,manure4 ,having now considered the nature of the different manures produced by the four common farm animals separately1 it is of importance to consider the exact nature of the fermentation1 decomposition1 or putrefaction which takes place in the manure-heap4 ,it is now more than thirty years since ,pasteur showed that the fermentation which ensued on keeping a sample of urine was due to the action of a minute organism1 for the propagation of which a certain amount of warmth1 air1 and moisture1 as well as the presence of certain food-constituents1 especially nitrogenous bodies1 were necessary4 ,subsequent researches by ,pasteur and others have conclusively demonstrated that the micro-organic life instrumental in effecting the putrefaction or decay of organic matter of any kind1 may be divided into two great classes3-- #a4 ,those which require a plentiful supply of oxygen for their development1 and which1 when bereft of oxygen1 die--known as aerobies4 #b4 ,those which1 on the contrary1 develop in the complete absence of oxygen1 and which1 when exposed to oxygen1 die--known as anaerobies4 ,in the fermentation of the manure-heap1 therefore1 we must conceive of the two classes of organisms as the active agents4 ,in the interior portion of the manure-heap1 where the supply of oxygen is necessarily limited1 the fermentation going on there is effected by means of the anaerobic organism--i4e41 the organism which does not require oxygen2 while on the surface portion1 which is exposed to the air1 the aerobic 7or oxygen-requiring7 organism is similarly active4 ,gradually1 as decay progresses1 the aerobic organisms increase in number4 ,it is through their instrumentality that the final products of decomposition are largely produced4 ,the functions of the anaerobic organisms may be1 on the contrary1 regarded as largely preparatory in their nature4 ,by breaking up the complex organic substances in the manure into new and simpler forms1 they advance the process of putrefaction through the initial stages2 and when this is accomplished1 they die and give place to the aerobic1 which1 as we have just seen1 effect the final transformation of the organic matter into such simple substances as water and carbonic acid gas4 ,the conditions influencing the fermentation of farmyard manure may be summed up as follows3#afc-- #a4 ,temperature4--,the higher the temperature the more rapidly will the manure decay4 #b4 ,openness to the ,air4--,of course it will be seen that the effect of exposing the manure to the action of the air is to induce the development of the aerobic type of organism1 and thus to promote more rapid fermentation4 ,if1 on the other hand1 the manure be impacted1 the slower but more regular fermentation1 due to the anaerobic type of organism1 will be chiefly promoted4 ,it must be remembered that in the proper rotting of farmyard manure both kinds of fermentation should be fostered4 ,it is1 in fact1 on the careful regulation of the two classes of fermentation that the successful rotting of the manure depends4 ,it must further be remembered that1 even with a certain amount of openness in a manure-heap1 anaerobic fermentation may take place4 ,this is due to the fact that the evolution of carbonic acid gas1 in such a case1 is so great as to exclude the access of the atmospheric oxygen into the pores of the heap4 #c4 ,the dampness of the manure-heap is another important influence4 ,this1 of course1 will act in two ways4 ,first1 by lowering the temperature4 ,where the manure-heap is found to be suffering from fire-fang1 the common method in practice is to lower the temperature by moistening the heap with water4 ,secondly1 it acts as a retarder of fermentation by limiting the supply of atmospheric oxygen1 and thus preventing1 as we have just seen1 aerobic fermentation4 #d4 ,the fourth chief influence in regulating fermentation of the manure-heap is its composition1 and more especially the amount of nitrogen it contains in a soluble form4 ,the rate at which fermentation takes place in any organic substance may be said chiefly to depend on the percentage of soluble nitrogenous matter it contains3 the greater this is in amount1 the more quickly does fermentation go on4 ,there are always a number of soluble nitrogenous bodies in farmyard manure4 ,these are chiefly found in the urine1 such as urea1 uric and hippuric acids1 and ammonia salts4 ,products of ,decomposition of ,farmyard ,manure4 ,the most important of the changes which take place in the rotting of farmyard manure may be briefly enumerated as follows3-- #a4 ,the gradual conversion into gases of a large portion of the organic elements in the manure4 ,of these gaseous products the most abundant is carbonic acid gas 7,,co#b74 ,it is in this form that the carbonaceous matter which constitutes the chief portion of the manure escapes into the air4 ,carbon also escapes into the air1 combined with hydrogen1 in the form of carburetted hydrogen or marsh-gas 7,,ch#d71 a product of the decomposition of organic matter in the presence of a large quantity of water4 ,this gas is consequently found bubbling up through stagnant water4 ,next to carbonic acid gas1 water 7,h#b,o7 is the most abundant gaseous product of decomposition4 ,the nitrogen present in the manure1 in different forms1 is converted by the process of decomposition chiefly into ammonia1 which1 combining with the carbonic acid1 forms carbonate of ammonia1 a very volatile salt4 ,it is to this fact that one of the great sources of loss in the decomposition of farmyard manure is due4 ,if the temperature of the manure-heap be permitted to rise too high1 the carbonate of ammonia volatilises4 ,it is probable1 also1 that a not inconsiderable portion of the nitrogen escapes into the air in the free state4 ,the last of the most important gaseous products of decomposition are sulphuretted and phosphoretted hydrogen4 ,it is to these gases that much of the smell of rotting farmyard manure is due4 #b4 ,the second class of substances formed are soluble organic acids1 such as humic and ulmic acids4 ,the function performed by these acids is a very important one4 ,they unite with the ammonia and the alkali substances in the mineral portion of the manure1 forming humates and ulmates of ammonia1 potash1 c4 ,it is these ulmates that form the black liquor which oozes out from the manure-heap4 ,in very rotten farmyard manure traces of nitric acid may be found2 but it must be remembered that the formation of nitrates is practically impossible under the ordinary conditions of active fermentation of farmyard manure1 except perhaps in its very last stages4 #c4 ,the third class of changes taking place have to do with the mineral portion of the manure4 ,the result of the formation of so much carbonic and other organic acids is to increase the amount of soluble mineral matter very considerably4 ,analyses of ,farmyard ,manure4 ,it is chiefly to the valuable researches of the late ,dr ,augustus ,voelcker that we owe our knowledge of the composition of old and fresh farmyard manure4 ,all interested in this important question should peruse the original papers on this subject contributed to the ',journal of the ,royal ,agricultural ,society' by ,dr ,voelcker4 ,typical analyses illustrating the variation in the composition of farmyard manure at different stages of decomposition will be found in the ,appendix4#afd ,from what has been already said1 it is obvious chat the composition of farmyard manure is of a very variable nature4 ,the quantity of moisture naturally varies most1 and this variation will depend on the age of the manure1 and the conditions under which it is permitted to decay4 ,it may be taken at from a minimum of #fe per cent in fresh to #hj per cent in well-rotted manure4 ,the total organic matter may be taken at from #ac to #ad per cent1 containing nitrogen 4#d to 4#fe per cent4 ,the total mineral matter will range from about #d to #f4e per cent1 containing of potash from 4#d to 4#g per cent1 and of phosphoric acid from 4#b to 4#d per cent4#afe ,as ,mr ,warington#aff has pointed out1 one ton of farmyard manure would thus contain #i to #ae lb4 of nitrogen1 about the same quantity of potash1 and #d to #i lb4 of phosphoric acid4 ,these quantities of nitrogen and phosphoric acid1 calculated to 7#ie per cent7 nitrate of soda1 and 7#ig per cent7 sulphate of ammonia1 and 7#be per cent7 superphosphate1 give respectively #eg4be to #if lb4 nitrate of soda1 #de to #ge lb4 sulphate of ammonia1 and #ce to #gi lb4 superphosphate4 ,that is1 in order to apply as much nitrogen to the soil as is contained in one ton of nitrate of soda1 we should require to use from #bc to #da tons of farmyard manure3 similarly one ton of sulphate of ammonia contains as much nitrogen as #cj to #ej tons farmyard manure4 ,in the same way one ton of superphosphate of lime contains as much phosphoric acid as #bh to #fd tons farmyard manure4 ,the value of rotten manure is1 weight for weight1 greater than that of fresh manure4 ,this is due to the fact that1 while the water increases in amount1 the loss of organic matter of a non-nitrogenous nature more than counterbalances the increase in water4 ,the manure1 therefore1 becomes more concentrated in quality4 ,the loss on the total weight1 according to ,wolff1 in the rotting of farmyard manure1 should not exceed in two or three months' time #af to #bj per cent--viz41 a sixth to a fifth of its entire weight4 ,not only1 however1 does the manure become richer in manurial ingredients1 but the forms in which the manurial ingredients are present in rotten manure are more valuable1 as they are more soluble4 ,these statements must not be taken as proving that it is more economical to apply farmyard manure in a rotten condition than in a fresh one4 ,the distinction must not be lost sight of which exists between relative increase--increase in the percentage of valuable constituents--and absolute increase4 ,the increase in the value of the manure by the changes of the manurial ingredients from the insoluble to the soluble condition may be effected at the expense of a considerable amount of absolute loss of these valuable ingredients4 ,this is a point which is probably too often left out of account in discussing the relative merits of fresh and rotten farmyard manure2 and it is important that it should be clearly understood4 ,in the words of the late ,dr ,voelcker3 ,direct experiments have shown that #ajj cwt4 of fresh farmyard manure are reduced to #hj cwt4 if allowed to lie till the straw is half rotten2 #ajj cwt4 of fresh farmyard manure are reduced to #fj cwt4 if allowed to ferment till it becomes 'fat or cheesy'2 #ajj cwt4 of fresh farmyard manure are reduced to #dj-ej cwt4 if completely decomposed4 ,this loss not only affects the water and other less valuable constituents of farmyard manure1 but also its most fertilising ingredients4 ,chemical analysis has shown that #ajj cwt4 of common farmyard manure contain about #dj lb4 of nitrogen1 and that during fermentation in the first period #e lb4 of nitrogen are dissipated in the form of volatile ammonia2 in the second1 #aj lb42 in the third1 #bj lb4 ,completely decomposed common manure has thus lost about one-half of its most valuable constituent4#afg ,while1 of course1 a very great amount of absolute loss of the valuable constituents--the nitrogen and ash-constituents--of farmyard manure may take place through volatilisation and drainage1 by taking requisite precautions this loss may be very much minimised4 ,as regards the total loss1 this1 in two or three months' time1 should only amount to #af to #bj per cent--or one-sixth to one-fifth of the weight4#afh ,the use of fixers1 to which reference has already been made1 will greatly minimise this loss4 ,the application of fixers is best made to the manure when still in the stall or byre4 ,the health of the animal benefits by so doing1 while the manure is at once guarded against loss from this source4 ,as to the relative merits of covered and uncovered manure-heaps1 much difference of opinion exists4 ,it is one of those questions which does not admit of final decision one way or another1 as it depends so largely on the individual circumstances of each case4 ,that manure produced under cover is more valuable than manure made in the open is readily granted4 ,the question1 however1 is as to whether the increase in its value is sufficiently great to warrant the extra expense involved in building covered courts4 ,this depends on the individual circumstances of each case1 and cannot be decided in a general way4 ,for experiments on the relative value of manure made under cover and in the open1 see ,appendix4#afi ,the method of applying farmyard manure to the field is a question which belongs more to the practical farmer than1 to the scientist1 and must be largely decided by economic considerations4 ,there is an aspect1 however1 of the question which may well be treated here4 ,the first point in the production of good manure is in connection with its even distribution4 ,it is of great importance that the excrements of the different farm animals be thoroughly mixed together4 ,by the intimate incorporation of the hot horse-dung with the cold cow and pig dung1 uniform fermentation is secured4 ,fire-fang--or too rapid fermentation--may occur from this not being properly done1 and from the manure becoming too dry4 ,it is important1 also1 as we shall see immediately1 to have the manure uniform in quality when applied to the field4 ,the manure ought to be firmly trodden down1 to moderate the rate of fermentation4 ,where the manure-heap is exposed to rain1 the quantity of water it will naturally receive will probably be quite sufficient1 if indeed not too much1 to ensure a proper rate of fermentation--except1 perhaps1 in very warm weather4 ,the great point to be aimed at is to ensure regular fermentation4 ,what has to be especially avoided is any sudden exposure of the manure to large quantities of water4 ,the result of such a washing-out of the soluble nitrogen is to retard fermentation1 besides incurring the risk of great actual loss by drainage4#agj ,application of ,farmyard ,manure to the ,field4 ,in applying the manure to the field1 and before ploughing it in1 two methods of procedure may be pursued4 ,first1 the manure may be set out in heaps1 larger or smaller1 over the field1 and be allowed to remain in these heaps some time before being spread2 and secondly1 it may be directly spread broadcast over the field1 and thus allowed to lie for some time4 ,lastly1 the manure may be ploughed in immediately2 and it may be stated that such a method is1 where circumstances permit1 the safest and most economical method4#aga ,in discussing the merits and demerits of these two methods1 ,dr ,heiden points out1 first1 with regard to the distribution of the manure in small heaps over the field1 that this is not to be recommended1 on the following grounds3-- #a4 ,because the chances of loss by volatilisation are thereby increased4 ,the manure is distributed several times instead of only once or twice4 #b4 ,it is apt to ensure unequal distribution4 ,the separate heaps run the risk of losing their soluble nitrogenous matter1 which soaks into the ground beneath the heaps4 ,the other portions of the field not covered by the manure-heaps are thus manured with washed-out farmyard manure1 bereft of its most valuable constituents4 ,the result is1 that while certain portions of the field are too strongly manured1 other portions are too weakly manured4 #c4 ,the proper fermentation of the manure is apt to be interfered with by the loss of that which is its most important agent--viz41 the soluble nitrogenous matter--and also by the drying action of the wind4 ,the same objections hold good to a large extent with regard to the setting out in the fields of the manure in large heaps4 ,the risks of loss1 in one respect1 may be said to be less1 owing to the smaller surface presented4 ,on the other hand1 they may be greater1 owing to fermentation taking place more quickly4 ,agricultural practice1 however1 often renders this custom necessary2 and if precautions are taken not to let the heap lie too long1 and to cover it over with earth1 the risk of serious loss may be rendered inconsiderable4 ,with regard to the second method of procedure--viz41 the spreading of the manure broadcast over the field1 and allowing it thus to lie--,dr ,heiden is of opinion that this should only be done when the field is level4 ,in the case of uneven ground the risks are1 of course1 obvious4 ,it has been affirmed that1 by allowing farmyard manure thus to lie exposed for some time1 an important loss of volatile ammonia--carbonate of ammonia--is apt to take place4 ,this could only take place where the former treatment of the farmyard manure had been bad4 ,hellriegel has shown that in the case of properly prepared farmyard manure there is no danger of loss in this way4 ,the absorptive power of the soil for ammonia1 it must be remembered1 is very great1 and the amount of volatile ammonia in farmyard manure is relatively so small that it is scarcely possible that any could escape in this way4 ,hellriegel's experiments have demonstrated this in a very striking way4 ,he has found that in the case of a chalky soil1 and during the summer and autumn months1 practically no loss of ammonia takes place4 ,the following considerations may be further urged in support of this method of application1 as against immediately ploughing in the manure1 viz43-- #a4 ,that fermentation takes place more quickly4 #b4 ,that it results in a more equable distribution of the manurial constituents in the dung1 by gradually and thoroughly incorporating the liquid portion of the manure with the soil-particles4 ,against1 however1 these undoubted advantages1 one serious disadvantage may be urged--viz41 that the manure1 before being ploughed in1 becomes robbed to a large extent of its soluble nitrogenous compounds1 which1 as we have repeatedly observed1 are so necessary for fermentation2 and that1 therefore1 when it is ploughed in1 it does not so readily ferment4 ,this being so1 it is highly advisable1 in the case of light or sandy soils1 not to follow such a practice1 but to plough the manure directly in4 ,as to the depth to which it is advisable to plough the manure in1 it may be here noticed that it should not be too deep1 so as to permit of the access of sufficient moisture to ensure proper fermentation1 and to prevent rapid washing down of nitrates to the drains4 ,lastly1 it need scarcely be pointed out that it is highly important to have the manure evenly and thoroughly incorporated with the soil-particles4 ,where the manure is permitted to cake together in lumps1 it may successfully resist the action of fermentation for several years4 ,value and ,function of ,farmyard ,manure4 ,practical experience has long demonstrated the fact that farmyard manure is1 taking it all round1 the most valuable1 and admits of the most universal application1 of all manures2 and science has done much to explain the reason of this4 ,the influence of farmyard manure is so many-sided that it is difficult even to enumerate its different functions4 ,as has already been pointed out1 its indirect value as a manure is probably as great as1 if indeed even not greater than1 its direct value4 ,in concluding our study of farmyard manure1 we shall endeavour to summarise1 in as brief a manner as possible1 its chief properties4 ,first1 as to its value as a supplier of the necessary elements of plant-food4 ,this1 there can be little doubt1 has been1 and still is1 grossly exaggerated by the ordinary farmer4 ,much has been claimed for it as a general manure4 ,how far it merits pre-eminence on this score among other manures will be seen in the sequel4 ,it is true that1 since it is composed of vegetable matter1 it contains all the necessary plant ingredients4#agb ,as has been shown in the ,introduction1 there is practically in the case of most soils no necessity to add to a manure any more than the three ingredients1 nitrogen1 phosphoric acid1 and potash4 ,its value1 then1 as a direct manure1 must depend on the quantity and proportion in which these three ingredients are present4 ,these substances1 as we have already seen1 it contains only in very small quantities4 ,it is1 judged from this point of view1 a comparatively poor manure4 ,furthermore1 only a certain percentage of these substances is in a soluble or immediately available condition1--in this respect the rotten manure being very much more valuable than the fresh manure4 ,again1 a point of great importance in a universal manure is the proportion in which the necessary plant-foods are present4 ,if it be asked1 ,are the nitrogen1 phosphoric acid1 and potash in farmyard manure present in the proportion in which crops require these constituents8 the answer must be in the negative4 ,heiden#agc has very strikingly illustrated this point1 in so far as the relations between the two ash ingredients are concerned1 by some computations as to the amount which would be removed from the soil in the course of different rotations4#agd ,in the case of five different rotations it was found that the ratio between the potash and phosphoric acid removed was as follows3#age 7#a7 #b4if to #a2 7#b7 #b4gf to #a2 7#c7 #b4ie to #a2 7#d7 #d4ac to #a2 7#e7 #c4gh to #a4 ,this would give a mean of #c4cb to #a4 ,this is not the ratio in which these ingredients are generally present in farmyard manure4 ,farmyard manure may be said to be much richer in the mineral constituents of plants than in nitrogen4 ,professor ,heiden found that in the case of a farm at ,waldau1 the crops in the course of ten years removed from a morgen 74#fca of an acre7 the following quantities3-- lb4 ,nitrogen #cbi ,potash #bfc ,phosphoric acid #aba ,in order to supply these amounts the following quantities of manure would require to be supplied3-- #a4 ,for the nitrogen1 #bf or #bg tons 7manure containing 4#fjf per cent nitrogen74 #b4 ,for the potash1 #bj to #be tons 7manure containing 4#fgb per cent potash74 #c4 ,for the phosphoric acid1 #ac to #ai tons 7manure containing 4#cae per cent phosphoric acid74 ,from the above it will be seen that farmyard manure contains too little nitrogen in proportion to its ash ingredients4 ,it is not merely the amount of fertilising ingredients removed by the crop we have to take into account in estimating the value of certain manurial ingredients for the different crops4 ,two other considerations have to be remembered--viz41 the amount of the constituents already present in the soil1 and the ability of the different crops to obtain the ingredients from the soil4 ,if we take into account these two considerations in estimating the value of farmyard manure as a general manure1 we shall find that they accentuate the inadequacy of the ratio existing between the nitrogen and the mineral ingredients4 ,messrs ,lawes and ,gilbert have found in the ,rothamsted experiments with farmyard manure1 that while it restored the mineral ingredients1 it was inadequate as a sufficient source of nitrogen4 ,nitrogen is1 of all manurial ingredients1 in least abundance in soils4 ,it is consequently found that the ingredient in which farmyard manure requires to be reinforced is nitrogen4 ,with regard to phosphoric acid and potash1 it has already been shown that the ratio between them is probably greater than that in a good average manure4 ,we should1 arguing from this alone1 be inclined to think that farmyard manure would be best reinforced with potash4 ,the reverse is the case1 however1 as every farmer knows4 ,this is due1 first1 to the fact that the potash1 unlike the phosphoric acid1 is entirely of a soluble nature1 and therefore immediately available for the plant's needs2 and secondly1 to the fact that the necessity for the application of potash as a manure is generally not nearly so great as in the case of phosphoric acid4 ,the result is1 that farmyard manure will be1 as a rule1 more valuably supplemented by phosphoric acid than by potash4 ,another point of great importance1 in estimating the value of farmyard manure as a chemical manure1 is the inferior value possessed by much of the nitrogen it contains1 as compared with the nitrogen in such artificial manures as nitrate of soda and sulphate of ammonia4 ,according to the ,rothamsted experiments1 weight for weight1 the nitrogen in farmyard manure is not half so valuable as it is in sulphate of ammonia4 ,much of the nitrogen becomes only very slowly available2 not a little of it perhaps actually takes years to be converted into nitrates4#agf ,thus1 with regard to the direct value of farmyard manure as a manure1 we have seen-- #a4 ,that it contains a very small quantity of the three fertilising ingredients4 #b4 ,that the proportion in which these three ingredients are present is not the best proportion for the requirements of crops4 #c4 ,that the form in which a portion of these ingredients--nitrogen and phosphoric acid--is present is not of the most valuable kind4 ,it is consequently not as a direct chemical manure that farmyard manure is pre-eminently valuable4 ,we must seek for perhaps its most valuable properties in its indirect influence4 ,it adds to the soil a large quantity of organic matter4 ,most soils are improved by the addition of humus4 ,the water-absorbing and retaining powers of a soil are increased by this addition of humus1 while it enables the soil to attract an increased amount of moisture from the air4 ,this is often of great importance1 as in the period of germination of seed4#agg ,the influence it exerts on the texture of the soil in the process of fermentation is also very great4 ,this is especially so in soils whose texture is too close1 such as heavy clayey soils4 ,it opens up their pores to the air1 and renders them more friable4 ,where such an influence is most required1 as in clayey soils1 the manure ought to be applied in a fresh condition1 so that the maximum influence exerted by the manure in this direction may be experienced4 ,on light soils1 on the contrary1 whose friability and openness are already too great1 and which do not require to be increased1 the manure will be best applied in a rotten condition4 ,it adds1 further1 greatly to the heat of the soils by its decomposition4 ,thus on cold damp soils it effects one very marked benefit4 ,the influence it exerts in its decomposition upon the fertilising ingredients present in the soil is also by no means inconsiderable4 ,in the process of its fermentation large quantities of carbonic acid gas are generated4 ,this carbonic acid probably acts in a double capacity4 ,it will1 in the first place1 greatly increase the solvent power of the soil-water1 and thus enable it to set free an increased amount of mineral plant-food2 and secondly1 it will help to conserve a certain quantity of the soil-nitrogen1 by preventing its conversion into nitrates4 ,as its indirect and mechanical properties are greatest when in its fresh condition1 it will be better to apply it in that condition to soils most lacking in these mechanical properties4 ,we may therefore say that farmyard manure is best applied in a rotted condition to light sandy soils1 and to soils in a high state of cultivation1 where its mechanical properties are not so much required4 ,an important point still remains to be discussed--viz41 the rate at which the farmyard manure should be applied4 ,this1 of course1 should naturally depend on a variety of circumstances--the amount of artificial manures used as supplementary to the farmyard manure1 the frequency of its application1 and the nature of the soil4 ,these considerations naturally vary so much1 that the quantities of farmyard manure it is advisable to apply in different cases are widely different4 ,there is a strong probability that the rate at which farmyard manure has been applied in the past has been grossly in excess of what could be profitably employed4 ,opinion is gaining ground among practical farmers1 that smaller and more frequent applications of farmyard manure to the soil would be fraught with better results than the older custom of applying a large dressing at a time4 ,this is an opinion in the support of which science can urge strong arguments4 ,it is only of late years that we have come to recognise sufficiently the various risks which all fertilisers are subject to in the soil1 and the importance1 therefore1 of minimising these risks as much as possible by putting into the soil at one time only as much manure as it is safely able to retain4 ,the famous old ,german writer ,thaer regarded #ag or #ah tons as an abundant dressing2 #ad tons he called good1 and #h or #i tons light4 ,other ,german authorities speak of #g to #aj tons as light1 #ab to #ah tons as usual1 #bj or more tons as heavy1 and #cj tons as a very heavy application4#agh ,in the new edition of ,stephens' ',book of the ,farm1'#agi from #h to #ab tons per acre for roots1 and from #ae to #bj tons for potatoes1 along with artificials1 which may cost from #bes4 to #fjs4 per acre additional1 are quoted as general dressings4 ,the majority of recent experiments with farmyard manure would seem to indicate that1 even in the case of what are considered small dressings1 the extra return in crop the first year after application is not such as to cover the expense of the manure4 ,of course1 as is commonly pointed out1 the effect of farmyard manure is of a lasting nature1 and is probably felt throughout the whole rotation1 or even longer4 ,this1 to a certain extent1 is no doubt true2 still it may be strongly doubted whether farmyard manure is1 after all1 an economical manure1 as compared with artificial manures4 ,the desirability of manuring the soil and not the crop is1 in this age of keen competition1 no longer believed in2 and the ,rothamsted experiments have shown that it is highly doubtful whether even the soil benefits to anything like a commensurate extent by the application of large quantities of farmyard manure4 ,this is of course assuming for farmyard manure the value that it would fetch when sold1 or1 to put it rather differently1 the price it would cost if the farmer had to purchase it4 ,farmyard manure is a necessary bye-product of the farm1 and can scarcely be regarded1 therefore1 in the same light as the artificial manures which the farmer buys4#ahj ,,footnotes3 #aca ,see ,appendix1 ,note ,i41 p4 #bgi4 #acb ,the large amount of potash in unwashed wool is very remarkable3 a fleece must sometimes contain more potash than the whole body of the shorn sheep4--,warington's ',chemistry of the ,farm1' p4 #gh4 #acc ,see ,appendix1 ,note ,,ii41 p4 #bgi4 #acd ,the urine of the pig1 from the nature of its food1 is1 as a general rule1 a very poor nitrogenous manure4 #ace ,see ,appendix1 ,note ,,xv41 p4 #bij4 #acf ,see ,appendix1 ,note ,,iii41 p4 #bhj4 #acg ,see ,appendix1 ,note ,,xviii41 p4 #bia4 #ach ,the nitrogen present in the urine1 it may be well to point out1 is derived from the waste of nitrogenous tissue as well as from nitrogenous matter of the food digested4 #aci ,note ,,iv41 p4 #bha4 #adj ,warington puts this matter admirably in the following words3 ,if the food is nitrogenous and easily digested1 the nitrogen in the urine will greatly preponderate4 ,if1 on the other hand1 the food is one imperfectly digested1 the nitrogen in the solid excrement may form the larger quantity4 ,when poor hay is given to horses1 the nitrogen in the solid excrement will exceed that contained in the urine4 ,on the other hand1 corn1 cake1 and roots yield a large excess of nitrogen in the urine4 7',chemistry of the ,farm1' p4 #acg74 #ada ,see p4 #bha4 #adb ,see p4 #bhb4 #adc ,see ,heiden's ',duengerlehre1' vol4 ii4 p4 #eh4 #add ,heiden's ',duengerlehre1' vol4 i4 p4 #djd4 #ade ,the following quantities of nitrogen are found in rye1 pea1 and bean straw3-- ,ranging from ,average ,lb4 per cent4 per cent4 per ton4 ,rye-straw 4#cj to 4#gc 4#eg #ab4gf ,pea-straw 4#gf to #a4fa #a4ba #bg4aj ,bean-straw #a4ae to #b4fb #a4ib #dc4jj #adf ,dr ,j4 ,m4 ,h4 ,munro recommends the sprinkling of a little finely sifted peat-powder in addition to straw1 as an excellent means of preventing loss of volatile ammonia in the fermentation of manure4 #adg ,see ',mark ,lane ,express1' ,october #g1 #ahhi1 p4 #dge4 #adh ,see ,appendix1 ,note ,,vii41 p4 #bhc4 #adi ,for analyses see ,appendix1 ,note ,,viii41 p4 #bhc4 #aej ,according to ,storer1 in a ton of autumn leaves of the best quality there would be #f lb4 of potash1 less than #c lb4 of phosphoric acid1 and #aj or #ae lb4 of nitrogen4 ,another substance that may be used as a litter is sawdust4 ,this substance is a good absorbent1 but is of little value as a manurial substance4 #aea ,heiden's ',duengerlehre1' vol4 ii4 pp4 #cd1 #ff4 ,in ,boussingault's experiments the food consisted of #ae lb4 hay1 #d4ed lb4 oats1 and #cb lb4 water2 the total excrements amounting to #ca4af lb41 containing #g4db lb4 dry matter4 ,in ,hofmeister's experiments the food consisted of #e4bc lb4 hay1 #f4ah lb4 oats1 #a lb4 chopped straw1 and #be4eg lb4 water2 the excrements amounting to #be4jg lb41 containing #e4cb lb4 dry matter4 #aeb ,this is taking no account of the amount of water which the manure will absorb1 and which will probably double the quantity4 #aec ,see ,appendix1 ,note ,,ix41 p4 #bhc4 #aed ,the rapid fermentation of horse-manure is due to its mechanical as well as its chemical nature4 ,the horse does not reduce its food to such small pieces1 and its urine is rich in nitrogen4 #aee ,schulze recommends one-third of a pound per day of sulphate of lime for each horse4 #aef ,see ,appendix1 ,note ,x41 p4 #bhd4 #aeg ,the food consisted of #cj lb4 potatoes1 #ae lb4 hay1 and #abj lb4 water4 #aeh ,for further analyses of cow-manure1 see ,appendix1 ,note ,,xi41 p4 #bhf4 #aei ,this is for a pig of six to eight months old1 and fed on potatoes4 #afj ,it has been asserted that the use of pig-manure1 when applied alone1 is apt to give an unpleasant taste to the produce grown4 #afa ,taken from a very large number of analyses by a number of experimenters4 ,see ,heiden's ',duengerlehre1' vol4 i4 p4 #ii4 #afb ,see ,storer1 ',agricultural ,chemistry1' vol4 ii4 p4 #if4 ,a question of great importance is as to the amount of farmyard manure produced on a farm in a year1 and its value4 ,this is a question which is extremely difficult to satisfactorily deal with4 ,various methods of calculating this amount have been resorted to4 ,it may be well to state these pretty fully4 ,some practical authorities estimate the amount by calculating that every ton of straw should produce #d tons of manure4 ,another method consists in estimating the amount from the size of the farm4 ,sir ,john ,lawes has calculated the composition of farmyard manure which should be produced in the case of a farm of #djj acres1 farmed on the four-course system4 ,he assumes that half of the roots and #ajj tons of hay are consumed at the homestead2 that the whole of the straw of the corn crops is retained at home as food and litter2 that twelve horses have corn equal to #aj lb4 of oats per head per day2 and that about ten shillings per acre are expended in the purchase of cake for feeding stock4 ,under these conditions the amount of farmyard manure should be #hee tons 7or an average of #h-a_/b tons for each of the #ajj acres of root-crop7 of fresh undecomposed dung4 7,for composition1 see ,appendix1 ,note ,,xvii41 p4 #bia47 ,another method is by taking1 as the data of calculation1 the number of cattle1 horses1 sheep1 c41 producing the manure4 ,lloyd considers that a fattening animal requires #c tons of straw in the year1 and makes about #ab tons of manure4 ,a farmer1 therefore1 should make #h tons of manure for every acre of that part of his land which1 in the four-course rotation1 is put down to turnips4 ,the last method consists in taking as the data the amount of food consumed and litter used in the production of the manure4 ,of these methods ,heiden considers the last as alone satisfactory and trustworthy4 ,applying this method to the horse1 he shows1 from experiments1 that a little over #dg per cent of the dry matter of its food has been proved to be voided in the solid and liquid excreta4 ,taking the average percentage of water in the excreta as about #gg4e1 the percentage of dry matter in the excreta will be #bb4e4 ,that is1 every pound of dry matter in the food eaten by the horse yields a little over #b lb4 of excrementitious matter4 ,to this of course must be added the amount of straw used as litter1 which may be taken at #f4e lb4 ,from these data we may calculate the amount of manure produced in a year by a horse1 making certain assumptions as to the amount of work performed4 ,this ,heiden does by assuming that a horse works #bfj days1 of twelve hours each1 in the course of a year1 or #acj whole days1 spending #bce days in the stall4 ,calculating from the above data1 he estimates that a well-fed working horse will produce about #ej lb4 of manure in a day1 or #f4e tons in a year4 ,of course this does not necessarily represent all the manure actually produced by the horse1 but how much of the remaining portion of the manure actually finds its way to the farm it is impossible to say4 ,according to the ',book of the ,farm1' ,division ,,iii4 p4 #ih1 a farm-horse makes about #ab tons of manure in a year4 ,it has been calculated that cows void about #dh per cent of the dry matter of their food in the solid and liquid excreta1 which contain of water1 on an average1 #hg4e per cent4 ,that is1 every pound of dry matter will furnish #c4hd lb4 of total excreta4 ,by adding the necessary amount of straw for litter 7which may be taken at one-third the weight of the dry matter of the fodder71 ,heiden calculates that an ox weighing #ajjj lb4 should produce #aac lb4 of manure in a day1 or #bj tons in a year4 ,the ',book of the ,farm1' ,division ,,iii4 p4 #ih1 gives the annual amount at from #aj to #ad tons4 ,according to ,wolff1 one may assume that on an average the fresh excrements 7both liquid and solid7 of the common farm animals 7with the exception of the pig7 contain of every #ajj lb4 of dry matter in the food consumed about #ej lb41 or a half4 ,estimating the dry matter in the litter used at equal to about #a_/d of the dry matter of the food1 this would mean that for every #ajj lb4 of dry matter consumed in food there would be #ge lb4 of dry manure 7viz41 #ej lb4 dry excrements #be lb4 dry litter71 which would yield #cjj lb4 of farmyard manure in the wet state--i4e41 with #ge per cent water4 ,the amount of food daily required per every #ajjj lb4 of live-weight of the common farm animals may be taken1 roughly speaking1 at #bd lb4 dry food material and #f lb4 of straw as litter4 ,the daily production of manure for #ajjj lb4 of live-weight would amount1 therefore1 to #ah lb4 of dry1 or #gb lb4 wet manure4 7,see ,appendix1 ,note ,,xvii41 p4 #bia47 ,according to ,j4 ,c4 ,morton and ,evershed1 oxen feeding in boxes require #bj lb4 of straw per head per day as litter4 ,an ox1 therefore1 will make #h tons of fresh dung in six months1 using #cb cwt4 of litter4 ,this means that each ton of litter gives #e tons of fresh dung4 ,it is calculated that nearly twice as much litter must be used in open yards4 #afc ,it has been calculated that under ordinary circumstances sheep-dung1 when allowed to ferment by itself1 should do so in about four months1 horse-dung in six months1 and cow-dung in eight months4 #afd ,see ,appendix1 ,note ,,xii41 p4 #bhf4 #afe ,see ,heiden's ',duengerlehre1' vol4 ii4 p4 #aef4 #aff ,warington1 ',chemistry of the ,farm1' p4 #cc4 #afg ,recent experiments by ,muentz and ,girard in ,france have shown that the loss in sheep excreta from volatilisation of the carbonate of ammonia amounted to over #ej per cent4 ,by the use of straw litter this was reduced to about a half less1 and with earth litter one quarter less4 #afh ,see ,appendix1 ,note ,,xiii41 p4 #bhh4 #afi ,see ,appendix1 ,note ,,xiv41 p4 #bhi4 #agj ,see ,appendix1 ,note ,,xv41 p4 #bij4 #aga ,for spring application rotten farmyard manure is generally used1 because in this condition its fertilising matter is more quickly available4 ,on light land it is best to apply it in the rotten condition shortly before it is likely to be used4 7,see p4 #bfa47 #agb ,the total amount of plant-food in a ton of farmyard manure is together less than #a_/bjth of its total weight4 #agc ,see ,heiden's ',duengerlehre1' vol4 ii4 p4 #aga4 #agd ,for full details see ,appendix1 ,note ,,xvi41 p4 #bij4 #age ,storer reproduces these results in his ',agricultural ,chemistry1' vol4 ii4 p4 #ba4 #agf ,this aspect of farmyard manure has been ably stated by ,mr ,f4 ,j4 ,cooke1 a well-known ,norfolk farmer4 ,in commenting on the results of the ,rothamsted experiments1 he says3 ,it is clear enough that the faith of the farmer in the soil-enriching character of his home-made manure is amply justified2 the only question being1 indeed1 if this quality be not too highly appreciated4 ,it is not1 after all1 so much by the fattening of our land as by the bounty of the crop grown upon it that we reap the fruit of our exertions4 ,the man of scientific mind keeps his purpose fixed on the production of good crops mainly1 and the cheapest way to grow them4 ,the experiments under consideration show that richness of land may be purchased much too dearly1 and that richness of crop by no means bears the necessary relation to richness of soil which has sometimes been imagined4 ,we may boast of the 'lasting qualities' of our dung1 but the answer of science by these experiments is1 that so great is the last that the life of one man may not be long enough to exhaust it4 ,in the extravagant use of dung1 therefore1 such considerations1 amongst many others1 as length of purse1 as well as length and character of tenure1 must clearly be taken into account4 #agg ,see paper on ,manurial ,experiments with ,turnips by author1 in ',transactions of the ,highland and ,agricultural ,society of ,scotland2' #ahia4 #agh ,storer's ',agricultural ,chemistry1' vol4 i4 p4 #dih4 #agi ,division ,,iii4 p4 #acj4 #ahj ,mr ,f4 ,j4 ,cooke1 who has already been quoted1 has kindly furnished the author with his views on the peculiar functions of farmyard manure as a manure4 ,he says3 ,i look upon it1 broadly speaking1 as chiefly of value in restoring to good land1 after cropping1 those particular advantages which good land alone can give1 and in helping better than any other manure1 when applied to poor land1 to bring it up to the level of good land in those particular merits which belong alone to fine soils4 ,i speak now of an inherent value in good soils1 beyond that attaching to them as mere reservoirs of abundant plant-food4 ,for instance1 one may supply a poor soil by artificial manure with much more food--and in a highly soluble condition--than is needed by the crop to be grown upon it1 and yet not get so good a crop as upon a naturally richer but otherwise similar soil less abundantly filled with immediately available food4 ,this may arise from a more perfect distribution of the plant-food in the rich soil1 or from the steady way in which it becomes available to the crop1 as well as for other reasons4 ,but whatever the cause1 there1 ,i think1 is the broad fact of the power of farmyard manure to enrich poor soils1 so to speak1 more naturally--that is1 in a way which makes them more nearly correspond to better soils than artificial manures can4 ,hence the indirect benefit to the farmer from farmyard manure is probably greater than its direct value as a mere manure4 ,and the usual provision and use of it amongst all straw-growing farmers is sufficiently justified4 ,the extent1 however1 to which that course may be beneficially carried1 is one of the most important of the many difficult economic and scientific problems which the farmer has to face4 ,on the economic side must of course be considered the cost of manufacture in individual instances1 as ruled by the market value of the straw1 and the different circumstances and conditions under which the various farm animals are kept and fed 7,i have the figures by me of one well-known farmer1 which show the cost to him of every ton of home-made manure to be #bjs4 or more72 the price the resultant crops may be expected to command2 the cost at the moment of artificial manures1 c41 c4 ,whilst on the scientific side must be considered the nature of the soil1 the particular rotation of crops1 c4 ,it was1 amongst others1 just these scientific and yet very definite and practical problems we have tried to throw light on in the series of field experiments conducted for several years by the ,norfolk ,chamber of ,agriculture4 7,see reprint of summary of same in last year's ,report of the ,board of ,agriculture47 ,,appendix ,,to ,,chapter ,,vii4 ,,note ,i4 7p4 #bbe74 ,,difference ,,in ,,amount ,,of ,,excreta ,,voided ,,for ,,food ,,consumed4 ,with regard to the difference in the composition of the solid excreta voided by different fattening animals fed on the same amount of food1 see ,warington's ',chemistry of the ,farm1' p4 #abe1 where it is shown that for equal amount of live-weight1 the sheep produces on the same weight of dry food very much more manure than the pig1 while the ox produces even more than the sheep4 ,of course this does not refer to the total amount of manure produced by the different animals1 but only to the amount of manure produced from the consumption of equal quantities of food4 ,this would seem to be owing to the greater capacity the pig has for assimilating its food4 ,,note ,,ii4 7p4 #bbg74 ,,solid ,,excreta ,,voided ,,by ,,sheep1 ,,oxen1 ,,and ,,cows4 ,to contrast with the analyses given by ,stoeckhardt1 it may be well to cite those based on ,lawes and ,gilbert's experiments1 and quoted by ,warington 7',chemistry of the ,farm1' p4 #ach73-- ,i4--,,sheep 7fed on meadow-hay74 ,,solid ,,excrement4 ,fresh4 ,dry4 ,water #ff4b - ,organic matter #cj4c #hi4f ,ash #c4e #aj4d ---- ---- ,nitrogen 4#g #b4j ,,ii4--,,oxen 7fed on clover-hay and oat-straw1 with #h lb4 beans per day74 ,fresh4 ,dry4 ,water #hf4c - ,organic matter #ab4c #hi4g ,ash #a4d #aj4c ---- ---- ,nitrogen 4#c #a4i ,,iii4--,,cows 7fed on mangels and lucerne hay74 ,mangels4 ,lucerne hay4 ,water #hc4jj #gi4gj ,nitrogen 4#cc 4#cd ,phosphoric acid 4#bd 4#af ,potash 4#ad 4#bc ,,note ,,iii4 7p4 #bcb74 ,,urine ,,voided ,,by ,,sheep1 ,,oxen1 ,,and ,,cows4 ,the following are the results for urine1 the animals being fed as in ,note ,,ii43-- ,sheep4 ,oxen4 ,fresh4 ,dry4 ,fresh4 ,dry4 ,water #he4g - #id4a - ,organic matter #h4g #fa4j #c4g #fc4j ,ash #e4f #ci4j #b4b #cg4j ---- ---- ---- ---- ,nitrogen #a4d #i4f #a4b #bj4f ,cows4 ,mangels4 ,lucerne hay4 ,water #ie4id #hh4be ,nitrogen 4#ab #a4ed ,phosphoric acid 4#ja 4#jjf ,potash 4#ei #a4fi ,,note ,,iv4 7p4 #bcc74 ,,percentage ,,of ,,food ,,voided ,,in ,,the ,,solid ,,and ,,liquid ,,excrements4 ,according to ,wolff1 the following table shows the percentage of the dry substance of the food which is voided in the solid and liquid excrements of the cow1 ox1 sheep1 and horse3-- ,cow4 ,ox4 ,sheep4 ,horse4 ,average4 ,solid excreta #ch4j #dd4j #db4f #df4g #db4h ,urine #e4h #f4c #f4h #e4g #f4b ---- ---- ---- ---- ---- ,total #dc4h #ej4c #di4d #eb4d #di4j ,,note ,v4 7p4 #bcd74 ,,pig ,,excrements4 ,the excrements voided by pigs are poor in manurial constituents1 because the food on which they are fed is generally of a very poor nature4 ,in their case the urine is always very much richer in manurial ingredients than the solid excreta4 ,the relative composition of the solid excreta and the urine will be best illustrated by quoting some experiments carried out by ,wolff on this subject4 ,the experiments were carried out with two pigs nine and a half months old1 and each #aba4i kilogrammes 7a kilogramme is equal to about #b-a_/d lb47 in weight4 ,the first consumed daily #ajjj grammes of barley1 #ejjj grammes of potatoes1 and #begb grammes of sour-milk4 ,the second one consumed the same quantities of potatoes and sour-milk as the first1 and #ajjj grammes of peas4 ,the following table gives the results of excreta and urine daily voided1 in grammes3-- ,dry ,nitrogen4 ,ash4 ,potash4 ,lime4 ,magnesia4 ,phosphoric substance acid4 ,solid ,i4 #bag4g #h4g #bh4f #g4c #d4d #c4j #aj4c excreta ,,ii4 #afa4a #i4a #ca4a #e4i #d4i #b4h #aa4a ,urine ,i4 #aab4h #ai4c #ef4b #cc4j #j4d #j4i #f4g ,,ii4 #acg4g #cj4f #fb4b #cg4a #j4b #a4a #g4a ,,note ,,vi47p4 #bcf74 ,,manurial ,,constituents ,,in #ajjj ,,parts ,,of ,,ordinary ,,foods4 ,based on ,lawes and ,gilbert's ,analyses4 7,warington's ',chemistry of the ,farm1' p4 #aci47 ---------------------------------------- ------------------------------ ,dry ,nitrogen4 ,potash4 ,phosphoric matter4 acid4 ---------------------------------------- ------------------------------ ,cotton-cake1 decorticated #iah #gj4d #ae4h #cj4e ,rape-cake #hhg #ej4e #ac4j #bj4j ,linseed-cake #hhc #dc4b #ab4e #af4b ,cotton-cake1 undecorticated #hgh #cc4c #bj4j #bb4g ,linseed #hhb #cb4h #aj4j #ac4e ,palm-kernel meal1 ,english #icj #be4j #e4e #ab4b ,beans #hee #dj4h #ab4i #ab4a ,peas #heg #ce4h #aj4a #h4d ,malt-dust #ije #cg4i #bj4h #ah4b ,bran #hfj #bc4b #ae4c #bf4i ,oats #hgj #bj4f #d4h #f4h ,rice-meal #ijj #ai4a #f4a #bc4h ,wheat #hgg #ah4g #e4b #g4i ,rye #heg #ag4f #e4h #h4e ,barley #hfj #ag4j #d4g #g4h ,maize #hij #af4f #c4g #e4g ,brewers' grains #bcd #g4h #j4d #c4i ,clover-hay #hdj #ai4g #ah4f #e4f ,meadow-hay #heg #ae4e #af4j #d4c ,bean-straw #hdj #ac4j #ai4d #b4i ,oat-straw #heg #f4d #af4c #b4h ,barley-straw #heg #e4f #aj4g #a4i ,wheat-straw #heg #d4h #f4c #b4b ,potatoes #bej #c4d #e4h #a4f ,swedes #ajg #b4b #b4j #j4f ,carrots #adj #b4a #c4j #a4a ,mangels #abj #a4h #d4f #j4g ,turnips #hj #a4f #b4i #j4h ---------------------------------------- ------------------------------ ,,note ,,vii4 7p4 #bda74 ,,analyses ,,of ,,stable-,,manure1 ,,made ,,respectively ,,with ,,peat-,,moss ,,litter ,,and ,,wheat-,,straw 7by ,,bernard ,,dyer1 ,b4,sc47 ,peat-moss litter4 ,wheat-straw4 ,per cent4 ,per cent4 ,total nitrogen #j4hh #j4fa ,equal to ammonia #a4jg #j4gd ,phosphoric acid #j4cg #j4dc ,equal to ,tribasic phosphate of lime 7or ,tricalcic phosphate7 #j4hj #j4id ,potash #a4jb #j4ei ,,note ,,viii4 7p4 #bdb74 ,,analyses ,,of ,,bracken 7by ,j4 ,,hughes1 ,f4,c4,s47 ,no4 #a ,no4 #b ,young fern4 ,old fern4 ,per cent4 ,per cent4 ,water #aa4ff #ad4ij 99 ,organic matter #hc4ch #hj4ed ,mineral matter #d4if #d4ef ------ ------ #ajj4jj #ajj4jj ------ ------ ,containing-- 99 ,nitrogen #b4db #j4ij ,silica #a4fj #b4ha ,potash #a4ae #j4aj ,soda #j4fd #j4bf ,lime #j4dd #j4fb ,magnesia #j4ac #j4dg ,phosphoric acid #j4fj #j4cj ,,note ,,ix4 7p4 #bdd74 ,,analyses ,,of ,,horse-,,manure4 ,for a fuller discussion of this question1 the reader is referred to ,heiden's ',duengerlehre1' vol4 ii4 p4 #ahe1 and also to ,storer's ',agricultural ,chemistry1' vol4 i4 p4 #ege4 ,the statements in the different text-books as to the quantity of manure produced by the horse are such as naturally to perplex the student4 ,this discrepancy is due1 however1 to the different methods adopted by different writers of calculating this amount4 ,the subject is further discussed in the footnote to p4 #beb4 ,the following analyses of horse-manure may be valuable for reference4 ,they are taken from ,storer's ',agricultural ,chemistry1' vol4 i4 p4 #dif3-- ---------------------------------------- -------------------- #a4 #b4 #c4 #d4 #e4 ,average4 ---------------------------------------- -------------------- ,water #ge4gf #fi4cj #fg4bc #gb4ac #ga4cj #ga4ae ,dry matter #bd4bd #bd4hb #cb4gb #bg4hg #bh4gj #bg4fg ,ash ingredients #e4jg #e4je #f4di #c4cg #c4cj #d4fe ,potash #j4ea #j4fc #j4bb #j4ei #j4ec #j4di ,lime #j4cj #j4gd #j4ag #j4da #j4ba #j4cf ,magnesia #j4ai #j4bi #j4bj #j4ag #j4ad #j4bj ,phosphoric acid #j4da #j4fg #j4ce #j4ab #j4bh #j4cf ,ammonia #j4bf #j4ab #j4ae #j4dd - #j4bd ,total nitrogen #j4ec #j4fi #j4dg #j4fg #j4eh #j4ei ---------------------------------------- -------------------- ,,note ,x4 7p4 #bdg74 ,,the ,,nature ,,of ,,the ,,chemical ,,reactions ,,of ,,ammonia ,,fixers4 ,for the student1 the exact nature of the chemical reactions taking place may be of interest4 ,in the first place1 it must be distinctly understood that the form in which ammonia escapes from the manure-heap is not1 as is so commonly erroneously stated in agricultural text-books1 as free ammonia4 ,whenever ammonia is brought into contact with carbonic acid1 carbonate of ammonia is formed4 ,when it is remembered that carbonic acid is by far the most abundant of the gaseous products of the decomposition of organic matter1 it will be at once seen that free ammonia could not exist under such circumstances4 #a4 ,in the case of hydrochloric acid1 the following chemical equation will represent the nature of the reaction-- #b;,h,cl 7,,nh#d7b;,,co#c #b,,nh#d;,cl ,h#b,o,,co#b 7,hydrochloric 7carbonate of ammonia17 7sal-ammoniac17 7carbonic acid47 acid17 #b4 ,in the case of sulphuric acid1 the equation will be-- ,h#b,,so#d 7,,nh#d7b;,,co#c 7,,nh#d7b,,so#d ,h#b,o,,co#b 7,sulphuric 7carbonate of 7sulphate of ammonia17 7carbonic acid47 acid17 ammonia17 #c4 ,with gypsum 7,ca,s,o#d7-- ,ca,s,o#d 7,,nh#d7b;,,co#c ,ca,c,o#c 7,,nh#d7b,,so#d 7,gypsum17 7carbonate of 7calcium 7sulphate of ammonia47 ammonia17 carbonate17 #d4 ,with copperas 7,fe,s,o#d7-- ,fe,s,o#d 7,,nh#d7b;,,co#c ,fe,c,o#c 7,,nh#d7b,,so#d 7,sulphate of 7carbonate of 7ferrous 7sulphate of ammonia47 iron17 ammonia17 carbonate17 #e4 ,with sulphate of magnesia 7,mg,s,o#d7-- ,mg,s,o#d 7,,nh#d7b;,,co#c ,mg,c,o#c 7,,nh#d7b,,so#d 7,sulphate of 7carbonate of 7carbonate of 7sulphate of magnesia17 ammonia17 magnesia17 ammonia47 ,reference has been made to the fact that magnesium sulphate may probably not only fix the ammonia1 but the phosphoric acid4 ,when magnesium sulphate1 soluble phosphoric acid1 and ammonia are brought in contact with one another1 the double insoluble phosphate of ammonium and magnesium 7,mg,n,h#d,,po#df;,aq7 is formed4 ,while such a reaction is possible1 it is highly improbable that it takes place to any extent4 ,the double phosphate is a crystalline salt which only separates after a considerable time1 and in the presence of a large excess of ammonia4 ,,note ,,xi4 7p4 #bej74 ,,analyses ,,of ,,cow-,,manure4#aha ---------------------------------------- -------------------------- #a4 #b4 #c4 #d4 #e4 #f4 ,average4 ---------------------------------------- ---------- ,water #he4cj #gg4ga #gd4jb #gb4hg #ge4jj #gg4ej #gg4jf ,dry matter #ad4gj #bb4cj #be4ih #bg4ac #be4jj #bb4ej #bb4ic ,ash ingredients #b4jd #d4ga #c4id #f4gj #f4bb #b4bj #d4cj ,potash #j4cf #j4df #j4ef #a4fi #j4ci #j4dj #j4fd ,lime #j4bi #j4cg #j4eh #j4da #j4bd #j4ca #j4dh ,magnesia #j4ai #j4aa #j4ac - #j4ah #j4aa - ,phosphoric acid #j4af #j4ac #j4jg #j4bj #j4ad #j4af #j4ad ,ammonia #j4jf #j4af #j4jg - #j4bg - #j4ad ,total nitrogen #j4ch #j4ed #j4da #j4gi #j4df #j4cd #j4dh ---------------------------------------- -------------------------- ,,note ,,xii4 7p4 #bei74 ,,composition ,,of ,,fresh ,,and ,,rotten ,,farmyard ,,manure 7,,voelcker74 ,composition of fresh manure1 composed of horse1 cow1 and pig dung1 about fourteen days old3-- ,water #ff4ag 99 ,soluble organic matter #b4dh ,soluble inorganic matter #a4ed ,insoluble organic matter #be4gf ,insoluble inorganic matter #d4je ------ #ajj4jj ------ 99 ,containing nitrogen 4#adi ,equal to ammonia 4#aha ,containing nitrogen 4#did ,equal to ammonia 4#eii ,total percentage of nitrogen 4#fdc ,equal to ammonia 4#ghj ,ammonia in a volatile state 4#jcd ,ammonia in form of salts 4#jhh ,composition of the whole ash3-- ,soluble in water1 #bg4ee per cent3-- ,soluble silica #d4be ,phosphate of lime #e4ce ,lime #a4aj ,magnesia #j4bj ,potash #aj4bf ,soda #j4ib ,chloride of sodium #j4ed ,sulphuric acid #j4bb ,carbonic acid and loss #d4ga ,insoluble in water1 #gb4de per cent3-- ,soluble silica #ag4cd ,insoluble silicious matter #aj4jd ,oxide of iron and alumina with phosphates #h4dg 7,containing phosphoric acid1 #c4ah per cent47 7,equal to bone-earth1 #f4hh per cent47 ,lime #bj4ba ,magnesia #b4ef ,potash #a4gh ,soda #j4ch ,sulphuric acid #a4bg ,carbonic acid and loss #aj4dj ------ #ajj4jj ------- ,composition of rotten dung1 six months old1 is as follows3-- ,water #ge4db 99 ,soluble organic matter #c4ga ,soluble inorganic matter #a4dg ,insoluble organic matter #ab4hb ,insoluble inorganic matter #f4eh ------ #ajj4jj ------ 99 ,containing nitrogen 4#big ,equal to ammonia 4#cfj ,containing nitrogen 4#cji ,equal to ammonia 4#cge ,total amount of nitrogen 4#fjf ,equal to ammonia 4#gce ,ammonia in a volatile state 4#jdf ,ammonia in form of salts 4#jeg ,composition of the whole ash3-- ,soluble in water1 #ah4bg per cent3-- ,soluble silica #c4af ,phosphate of lime #d4ge ,lime #a4dd ,magnesia #j4ei ,potash #e4eh ,soda #j4bi ,chloride of sodium #j4df ,sulphuric acid #j4gb ,carbonic acid and loss #a4bh ,insoluble in water1 #ha4gc per cent3-- ,soluble silica #ag4fi ,insoluble silica #ab4ed ,phosphate of lime - ,oxides of iron alumina with phosphates #aa4gf 7,containing phosphoric acid1 #c4dj per cent47 7,equal to bone-earth1 #g4cf per cent47 ,lime #bj4gj ,magnesia #a4ag ,potash #j4ef ,soda #j4dg ,chloride of sodium - ,sulphuric acid #j4gi ,carbonic acid and loss #af4je ------ #ajj4jj ------ ,,note ,,xiii4 7p4 #bfc74 ,,comparison ,,of ,,fresh ,,and ,,rotten ,,manure 7,,wolff74 ,fresh4 ,moderately rotten 7,taking the quantity of dry matter as the same47 ,dry matter #be4jj #be4jj ,ash #c4ha #d4gf ,nitrogen #j4ci #j4di ,potash #j4de #j4ef ,lime #j4di #j4fa ,magnesia #j4ab #j4ae ,phosphoric acid #j4ah #j4bc ,sulphuric acid #j4aj #j4ac ,silica #j4hf #a4jh ,,note ,,xiv4 7p4 #bfc74 ,,lord ,,kinnaird',s ,,experiments4#ahb ,lord ,kinnaird has given the particulars of a very careful experiment4 ,he tried to test the comparative value of manure kept in an open court with that kept under cover4 ,he selected the same kind of cattle1 gave them the same kind and quantity of food1 and bedded them with the same kind of straw4 ,a field of #bj acres of uniform land was selected4 ,this having been equally divided1 #b acres out of each #aj gave the following results3-- ,potatoes grown with ,uncovered ,manure4 ,tons4 cwt4 lb4 ,first measurement--#a acre produced4 #g #f #h ,second do4 do4 do4 #g #ah #ii ,potatoes grown with ,covered ,manure4 ,first measurement--#a acre produced4 #aa #ag #ef ,second do4 do4 do4 #aa #ab #bf ,this shows an increase of about #d tons of potatoes per acre with the covered manure4 ,the next year the weather was wet1 grain soft and not in very good order1 but the following was the amount of produce3-- ,wheat grown with ,uncovered ,manure4 ,weight per ,produce in grain4 bushel4 ,produce in straw4 ,acre4 bushels4 lb4 lb4 stones4 lb4 ,first #da #ai #fa-a_/b #aeb of #bb ,second #db #ch #fa-a_/b #afj of #bb ,wheat grown with ,covered ,manure4 ,first #ec #e #fa #bbj of #bb ,second #ec #dg #fa #baj of #bb ,,note ,,xv4 7pp4 #bca1 #bfd74 ,,drainings ,,of ,,manure-,,heaps4 ,the importance of not separating the liquid portion from the solid portion has already been pointed out in dealing with the composition of the solid excreta and the urine4 ,these two constituents of the manure are complementary to one another1 and the value of farmyard manure as a general manure is very much impaired if the liquid portion is not applied along with the solid4 ,in one important respect do the drainings of manure-heaps differ from urine--that is1 in the percentage of phosphates they contain1 the latter being practically devoid of phosphoric acid4 ,the following is an analysis of drainings from a manure-heap 7,wolff73-- ,dry substance #ah4j ,magnesia #j4d ,ash #aj4g ,phosphoric acid #j4a ,nitrogen #a4e ,sulphuric acid #j4g ,potash #d4i ,silica #j4b ,lime #j4c ,,note ,,xvi4 7p4 #bgj74 ,,amounts ,,of ,,potash ,,and ,,phosphoric ,,acid ,,removed ,,by ,,the ,,following ,,rotations ,,from ,a ,,prussian ,,morgen 74#fca ,,acre74 ,potash4 ,phosphoric acid4 lb4 lb4 #a4 ,wheat #af4dj #aj4fg ,oats #aj4dg #d4ei ,potatoes #ff4da #ah4cc ,hay #ci4ed #aa4cb ------ ----- #acb4hb #dd4ia ------ ----- ,the ratio of potash to phosphoric acid is #b4if to #a4 #b4 ,wheat #af4ij #aj4fg ,barley #ag4dd #aj4fe ,potatoes #ff4da #ah4cc ,hay #ci4ed #aa4cb ------ ----- #adj4bi #ej4ig ------ ----- ,the ratio of potash to phosphoric acid is #b4gf to #a4 #c4 ,rye #bj4jc #ab4ae ,oats #aj4ig #d4ei ,potatoes #ff4da #ah4cc ,hay #ci4ed #aa4cb ------ ----- #acf4ie #df4ci ------ ----- ,the ratio of potash to phosphoric acid is #b4ie to #a4 #d4 ,wheat #af4ij #aj4fg ,oats #aj4ig #d4ei ,mangels #adh4ed #be4fb ,hay #ci4ed #aa4cb ------ ----- #bae4ie #eb4bj ------ ----- ,the ratio of potash to phosphoric acid is #d4ac to #a4 #e4 ,rye #bj4jc #ab4ae ,barley #ag4dd #aj4fe ,mangels #adh4ed #be4fb ,hay #ci4ed #aa4cb ------ ----- #bbe4ee #ei4gd ,the ratio of potash to phosphoric acid is #c4gh to #a4 ,,note ,,xvii4 7pp4 #bec1 #bed74 ,,composition ,,of ,,farmyard ,,manure 7,,fresh71 7calculated by ,,sir ,,john ,,lawes74 ,phosphoric acid ,total dry ,total mineral calculated as ,potash4 ,nitrogen4 matter4 matter4 phosphate of lime4 ,percent #cj4j #b4gg 4#ej 4#ec 4#fd ,per ton 7in lb47 #fg4b #fb4j #aa4a #ab4j #ad4c ,,note ,,xviii4 7p4 #bcb74 ,,the ,,urine4 ,an important consideration we have omitted to take note of in the text is the quantity of the urine voided4 ,it is this consideration that renders the urine so much more valuable than the solid excreta4 ,in the case of a man it has been estimated that the urine voided is fifteen times as much1 is twelve times as rich in nitrogen1 three times in potash1 and two in phosphoric acid1 as the solid excreta 7,munro74 ,the relation of solid matter in the case of the farm animals is not exactly similar4 ,the urine of the ox is about twice the weight of its solid excreta4 ,both the horse and the sheep1 however1 void as a rule more solid excreta than urine4 ,munro1 in his work on ',soils and ,manures1' contrasts the composition of the urine and solid excreta of the different farm animals by the following statement3-- #a ton of urine contains #a ton of solid excreta in lb43 contains in lb43 ,nitrogen4 ,potash4 ,nitrogen4 ,cow #cj #bj #i ,horse #cf #bb #ab ,sheep #ch #cj #af ,,footnotes3 #aha ,storer's ',agricultural ,chemistry1' vol4 ,i4 p4 #dif4 #ahb ,scott's ',manures and ,manuring1' p4 #ai4 ,,chapter ,,viii4 ,,guano4 ,importance in ,agriculture4 ,in the consideration of artificial manures1 guano deserves the first place4 ,this it does mainly on historical grounds1 as it is now largely a manure of the past4 ,not merely has it been used in agriculture to an extent to which no other artificial manure has as yet ever approximated1 but its influence on agricultural practice has been enormous4 ,introduced into this country about the middle of the present century1 it was the first of artificial manures to be used in large quantities4#ahc ,it may be thus described as having introduced the modern system of intensive cultivation1 and given rise to the now almost universal practice of artificial manuring4 ,influence on ,british ,farming4 ,it is1 indeed1 difficult to over-estimate the important influence which the introduction of this most valuable fertiliser has exercised on ,british as well as1 to a large extent1 on ,european husbandry4 ,before its introduction the farmer was almost completely dependent on his farmyard manure4 ,he was tied down to a great extent1 by the exigencies of the then prevailing agricultural customs1 to certain rotations of crops4 ,he could do little in the way of enriching barren soils or of ensuring a heavy yield of crop4 ,by the use of this very potent fertiliser1 he quickly discovered that the most wonderful results ensued--results which must have seemed to him at first little short of miraculous4 ,he found that by the application of a few hundredweights per acre1 poor soils could be made to yield large returns1 and that barren patches in a field could be brought up to the average of the surrounding portions by sprinkling merely a few handfuls of it2 that by its means a good start could be ensured to every crop1 and one slow of coming away could be hastened on4 ,in short1 in this wonderful brown powder1 with such a characteristic odour1 the astonished farmer discovered a manure which1 for the speed of its action1 and for the increase of crop it gave1 completely threw into the shade both farmyard manure and bones4 ,what wonder1 then1 that its fame as a manure should have become so quickly known and its use so extensive6 ,it thus gave a most powerful impetus to intelligent farming by bringing home to the minds of those who used it the important position nitrogen and phosphates occupied as constituents of the soil1 and the influence they exercised on plant-growth4 ,it furnished1 in fact1 on an enormously large scale1 a practical demonstration of the principles of manuring4 ,the educational value which the use of guano thus exercised may be said to have been very great4 ,it also led the way to the use of the various artificial manures so much used during the last fifty years4 ,impressed by the value of guano1 farmers were favourably disposed towards the use of other fertilisers2 and1 largely owing to its widespread popularity1 the new practice speedily gained ground4 ,influence not wholly for ,good4 ,but its influence1 it must be admitted1 was not wholly for good4 ,in its very popularity lay the danger of its abuse4 ,had its value and the method of its action been more widely understood1 and had the principles upon which the practice of artificial manuring depends been better realised1 agriculturists would have been spared much of the needless pecuniary losses they sustained by being imposed upon by unscrupulous manure-dealers4 ,among the farming community the word guano soon became a name to conjure with1 and under this title many spurious and worthless manures were attempted to be palmed off on the unwary farmer4 ,even the genuine article1 there can be little doubt1 was at one time largely adulterated2 and as the farmer was almost invariably content to purchase the article not on any guaranteed chemical analysis1 but simply on the ground of its appearance1 colour1 and more especially smell1 every facility was given for the successful perpetration of such fraudulent imposition4 ,guano1 it was very soon found1 varied in its composition1 but this variation in quality the farmer did not recognise4 ,in the early days of its use all guano was in his eyes of the same value4 ,too often1 as we have just pointed out1 provided it had a good colour and a strong odour1 it was all right4 ,under such conditions1 it can scarcely be wondered at that its introduction should have proved not an unmixed blessing to agriculture4 ,its ,value as a ,manure4 ,guano derives its value as a manure from the nitrogen1 phosphates1 and the small amount of potash it contains4 ,this at any rate is true of the great bulk of guano which has been used in the past4 ,there are1 as we shall immediately see1 certain kinds of guano1 known as phosphatic guanos1 which only contain phosphates4 ,the amount of such purely phosphatic guano directly used as a manure in this country is1 however1 inconsiderable1 and guano may truly be described as owing its value chiefly to its nitrogen4 ,not a little of its value and popularity as a manure may be said to be due to the fact that it contains all of the three important manurial constituents1 and that in this respect it may be regarded in a sense as a general manure1 thus resembling most nearly1 of all artificial manures1 farmyard manure4 ,although its sources are now1 to a very large extent1 exhausted1 and its total annual imports into this country are at present considerably less than what they were thirty or forty years ago1#ahd it may be well1 on account of its historical importance1 to give a somewhat detailed account of its origin1 occurrence1 and value as a manure4 ,origin and ,occurrence4 ,guano 7which means dung7--or huano1 as it is spelt in the ,spanish language--was first used in ,peru4 ,it seems to have been used there long before that country was discovered by the ,spaniards--probably as early as the twelfth century4 ,regarding its origin there can be little doubt4 ,it is almost entirely derived from the excrements of sea-birds1 such as pelicans1 penguins1 and gulls1 as well as from the remains of the birds themselves1 and of seals1 walruses1 and various other animals4#ahe ,under the influence of a tropical sun1 and in a region in which rain scarcely ever falls1 these excrements are soon dried1 and remain little changed in their composition through centuries4 ,many of the ,peruvian deposits must be extremely old1 as they are covered up with sand and other debris1 and are of considerable depth4 ,especially is this the case with deposits occurring on the mainland1 such as those at ,pabellon de ,pica1 where the layer of sand or conglomerate covering up the deposit varies in depth from a few feet to over a hundred4 ,the effect of this superficial covering has been to protect the guano1 to a certain extent1 from loss of nitrogen4 ,although guano of the best class has been derived from the neighbourhood of ,peru1 deposits have also been found in many other parts of the world--viz41 in ,north ,america1 ,west ,indies1 ,australia1 ,asia1 ,africa1 and among the islands of the ,pacific4#ahf ,variation in the ,composition of different ,guanos4 ,the guano found in these different deposits varies very considerably in composition4 ,this is due to the difference in the nature of the prevailing climate of the places where these deposits occur4 ,where the climate is dry and warm1 as is the case in ,chili and ,peru1 the excrements dry quickly and remain very little changed1 as one very important condition of fermentation--viz41 moisture--is absent4#ahg ,in a damp climate1 on the other hand1 speedy fermentation ensues1 resulting in the loss of nearly all the organic matter1 including nitrogen1 in such volatile forms as carbonate of ammonia1 carbonic acid gas1 water1 c4 ,the soluble alkalies1 the most important of which is potash1 as well as the soluble phosphates1 are also1 under such conditions1 lost to the guano by being washed out by the rain4 ,we have thus a wide difference in the quality of the different deposits1 depending on the extent to which decomposition has taken place4 ,guano thus ranges from the rich nitrogenous ,peruvian kind1 which has undergone little or no change from the time of its deposit1 to the purely phosphatic kind 7such as those of ,malden and ,baker islands71 in which everything of manurial value has been lost except the insoluble phosphate of lime4 ,even among the nitrogenous guanos we find a considerable difference in quality1 some deposits being partially impoverished by the action of the atmospheric moisture1 dew1 spray or sea-water1 but still containing a considerable proportion of their nitrogen4 ,other deposits1 again1 are largely admixed with sand1 which has been blown in upon them to such an extent as to make them unsaleable4 ,we can divide guano1 therefore1 into two great classes--viz41 nitrogenous and phosphatic4 ,i4--,,nitrogenous ,,guanos4 7a7 ,,peruvian4 ,by far the most valuable and abundant deposits as yet discovered have been those on the ,peruvian and ,chilian coasts4 ,as already pointed out1 guano seems to have been used in this country from a very early period2 and so impressed were the ,incas with its importance as a manure1 that the penalty of death was imposed on any one guilty of killing the sea-fowl during the breeding season in the vicinity of the deposits4 ,the occurrence of guano in ,peru seems first to have been made known in ,europe in the beginning of the eighteenth century4 ,it was not1 however1 till the beginning of the present century--viz41 #ahjd--that ,a4 ,humboldt1 the great ,german traveller1 brought some of the wonderful fertiliser home with him1 and that its composition was able to be investigated by chemical analysis4 ,shortly afterwards1 its practical value was demonstrated by experiments carried out on potatoes by ,general ,beatson in ,st ,helena4 ,to ,lord ,derby is due the credit of having first introduced it into this country1 the earliest importation into ,liverpool being in #ahdj4 ,experiments were shortly afterwards instituted in different parts of the country1 prominent among which were those by ,sir ,john ,lawes and ,sir ,james ,caird2 and so striking were the results obtained1 that the manure rapidly found favour with the farming community--so much so1 that ten years later the importations into this country amounted to no less than #bjj1jjj tons1 while in #ahee the total exports from the west coast of ,south ,america reached the enormous amount of #djj1jjj tons4 ,in all1 it has been estimated that since the year #ahdj over #e1jjj1jjj tons of ,peruvian guano have been imported into this country4 ,different ,deposits4 ,peruvian guano has been derived from various deposits occurring in different parts of the coast1 and from a number of small adjacent islands4 ,the richest of these was that found on ,angamos1 a rocky promontory on the coast of ,bolivia4 ,samples of this guano contained as high as #bj per cent of nitrogen 7equal to #bd per cent ammonia74#ahh ,unfortunately1 however1 the quantity of this deposit was extremely limited1 and became rapidly exhausted4 ,next to this deposit in quality was the guano found on the ,chincha islands1 three little islands off the coast of ,peru4 ,these deposits were the largest which have ever been discovered1 and for a period of nearly thirty years were almost the sole source of the ,peruvian guano sold in commerce1 over #aj1jjj1jjj tons having been exported from them alone4 ,some of this guano contained #ad per cent of nitrogen 7equal to #ag per cent ammonia72 and although part of the guano shipped from these islands was not quite so rich1 yet it was all of a high-class order4 ,the deposits on these islands were in many cases #ajj to #bjj feet in depth1 and rested on rocks of granite4 ,the lower layers were consequently found to be poorer in quality1 and mixed with pieces of granite4 ,the ,chincha island deposits have been long exhausted1#ahi and the chief deposits of ,peruvian guano since worked have been those on ,guanape and ,macabi islands--a considerably inferior guano1 containing only #i to #aa per cent of nitrogen 7equal to #aa to #ac per cent of ammonia7--which in their turn have become exhausted2 from ,ballestas1 almost as rich as the ,chincha island guano1 also now exhausted2 and from ,pabellon de ,pica1 ,punta de ,lobos1 ,huanillos1 ,independence ,bay1 and ,lobos de ,afuera4 ,quite recently a deposit of very high-class guano was discovered in ,corcovado1 and a good many cargoes have already been shipped to this country4 ,it is found to contain nitrogen equal to from #aj to #ac per cent ammonia1 #cj to #ce per cent phosphates1 and some potash1 being thus a most valuable guano4 ,appearance1 ,colour1 and ,nature4 ,in colour it varies from a very light to a very dark brown1 the richer samples being generally lighter4 ,samples taken from even the same deposit have been found to differ very considerably in appearance1 those taken from the lower and older layers being usually darker than those taken from the more recent upper layers4 ,it was soon found also to vary very much in composition4 ,after a deposit had been worked for some time1 the quality of guano it yielded was found to be inferior and coarser1 and in many cases mixed with pebbles or pieces of granite1 porphyry1 c4 ,this led to the custom of screening it on arrival in this country1 before it was used as a manure4 ,in the richer qualities--e4g41 in the ,chincha guano--little round concretionary nodules1 varying in colour from pure white to dark brown1 were occasionally found4 ,analysis showed these nodules#aij to be composed chiefly of potash salts4 ,sometimes1 also1 little crystals of almost pure ammonia salts were found4 ,it soon became customary1 therefore1 to prepare guano for the market by separating the stones and reducing the whole to a fine uniform powder4 ,one of its most characteristic properties1 and the one which seems to have impressed the public most1 was its pungent odour4 ,undue importance was attached to this property1 in the belief that it was caused by the ammonia it contained4 ,it may be doubted1 however1 whether the characteristic smell of guano is due so much to its ammonia as to certain fatty acids4 ,composition4 ,in composition it is of a most complex nature4 ,it contains its nitrogen in a great variety of forms1 the chief of these being urate1 oxalate1 ulmate1 humate1 sulphate1 phosphate1 carbonate1 and muriate of ammonia2 and also in a rare form of organic nitrogen peculiar to guano1 called guanine4 ,according to ,boussingault1 some guanos contain small quantities of nitrates4 ,its phosphoric acid is present both in the soluble state--viz41 as phosphates of the alkalies 7ammonia and potash7--and in the insoluble state as phosphate of lime2 and lastly1 its potash is present as sulphate and phosphate4 ,the proportion in which these different forms of nitrogen and phosphoric acid are present varies considerably in different samples4 ,the richer a sample1 as a rule1 the more nitrogen in the form of uric acid it contains4 ,the most of the nitrogen is present as uric acid and ammonia4 ,damp guanos contain more of their nitrogen as ammonia than dry ones1 this being due to the fermentation which goes on in the former4 ,on an average1 about a third of its total nitrogen is soluble in water4 ,of its phosphates1 on the other hand1 only about a fourth are soluble in water4 ,the following analyses of a sample of ,chincha island guano by ,karmrodt#aia will illustrate this4 7,sample dried at #bab deg4 ,fahr473-- #a4 ,constituents easily soluble in ,water4 ,urate of ammonium #ab4gd ,oxalate of ammonium #ac4fj ,nitrogenous and sulphurous organic substances #c4fa ,ammonium-magnesium phosphate #d4jj ,ammonium phosphate 4#ij ,ammonium sulphate #a4hb ,ammonium chloride #a4ee ,potassium sulphate #c4cj ,sodium chloride #b4dd ----- #dc4if ----- #b4 ,difficultly soluble in ,water1 soluble in ,acids1 ,alcohol1 and ,ether4 ,uric acid #ba4ad ,resin #a4aa ,fatty acids #a4fj ,nitrogenous and sulphurous organic substances #b4bi ,calcium phosphate #ah4bb ,phosphate of iron #a4jd ,silica 4#fd ----- #df4jd ----- ,in the above analysis it will be noticed that none of the ammonia is present as carbonate4 ,in most samples1 however1 of ,peruvian guano1 the ammonia in this form amounted to from #a to #b per cent4 ,in the inferior qualities1 chiefly those which had been subjected to the action of water1 and consequently of fermentation1 to a certain extent1 this form of ammonia was found to be most abundant4 ,such guanos were most liable to loss of nitrogen by volatilisation4 ,the older ,peruvian guano contained as high as #ad per cent of nitrogen 7equal to #ag per cent of ammonia71 and of phosphoric acid #ab to #ad per cent 7equal to #bf to #bh per cent of phosphate of lime74 ,it1 however1 gradually deteriorated in quality as the deposits became worked out1 the percentage of nitrogen becoming year by year less1 until latterly ,peruvian guano1 as imported1 contains only from #c to #d per cent of nitrogen 7equal to #d to #e per cent of ammonia74 ,this guano is1 however1 richer in phosphates1 containing often #ej to #fj per cent of phosphate of lime1 and #c to #d per cent of potash4#aib 7b7 ,,other ,,nitrogenous ,,guanos4 ,the guanos1 other than those which come from ,peru1 are chiefly purely phosphatic guanos1 so that the term ,peruvian has not unfrequently in the past been used as a generic term synonymous with the term nitrogenous1 and consequently applied to all nitrogenous guanos independent of their source4 ,there are1 however1 a few deposits other than the ,peruvian which have yielded considerable quantities of valuable nitrogenous guano4 ,of those1 the richest in quality--in fact1 the richest of any deposits hitherto discovered--was the ,angamos guano1 which came from a rocky promontory on the coast of ,bolivia4 ,the few samples of this which have been analysed showed over #bj per cent of nitrogen4 ,unfortunately1 the deposit proved to be comparatively insignificant in amount1 and has long been exhausted4 ,poorer in quality1 but more abundant in quantity1 were the deposits found on the ,ichaboe and other islands off the south-west coast of ,africa4 ,these deposits were discovered shortly after the introduction of ,peruvian guano1 and for a few years supplied considerable quantities of valuable manure4 ,the deposits first discovered were soon exhausted1 so that for a number of years ,ichaboe guano ceased to be procurable4 ,fresh deposits1 however1 were subsequently found1 and considerable quantities have of late years been used in agriculture4#aic ,ichaboe guano is inferior in value to ,peruvian4 ,it exemplifies the influence of small quantities of rain on guano deposits in impoverishing them in their nitrogen4 ,in much of the ,ichaboe guano imported into this country a large amount of feathers is found4 ,it also contains an abnormally large quantity of insoluble matter4 ,among the other nitrogenous guanos may be mentioned the ,patagonian1 ,falkland1 and ,saldanha ,bay4 ,they are1 like the ,ichaboa1 of comparatively recent origin1 and are collected in small quantities after the breeding season every year4 ,,ii4--,,phosphatic ,,guanos4 ,phosphatic guanos1 as already pointed out1 are similar in origin to nitrogenous guanos4 ,in their case1 however1 the nitrogen1 alkalies1 and soluble phosphates which they originally contained have been almost entirely lost by the decomposition of their organic matter and the action of water4#aid ,most of them still contain very small quantities of nitrogen1 amounting to a fraction of a per cent4 ,of these deposits there are very many occurring on islands in different parts of the world4 ,in appearance the guano obtained from them is very different from nitrogenous guano1 being much lighter in colour1 and of a fine powdery nature4 ,it forms a very rich phosphatic guano1 containing in many cases between #gj and #hj per cent of insoluble phosphate of lime4 ,such guanos are largely used in the manufacture of high-class superphosphates1 by treating them with sulphuric acid4 ,being of an insoluble nature1 they are not very suitable for direct application to the soil4 ,of these phosphatic guanos the following are the chief--those marked in italics being still unexhausted3-- #a4 ,baker1 ,jarvis1 ,howland1 ,starbuck1 ,flint1 ,enderbury1 ,malden1 ,lacepede1 ,browse1 ,huon1 ,chesterfield1 ,sydney1 ,phoenix1 ,arbrohlos1 ,shark's ,bay1 and ,timor--all found on islands in the ,pacific ,ocean4 #b4 ,mejillones1 on the coast of ,bolivia4 #c4 ,aves1 ,tortola1 ,mona1 and other deposits in the ,west ,indies4 #d4 ,kuria ,muria islands1 in the ,arabian ,gulf4 ,for further particulars as to the composition of these different guanos1 the reader is referred to the ,appendix1 ,note ,v41 p4 #cbi4 ,inequality in ,composition4 ,that guano was a substance of by no means uniform composition was a fact early recognised in the history of the trade4 ,not only did guano from different deposits show on analysis different percentages of the manurial ingredients1 but different samples of guano from the same deposit were often found to differ very considerably from one another4 ,it soon became the custom1 therefore1 to sell it on chemical analysis1 each separate cargo being carefully analysed4 ,but this custom did not wholly obviate the difficulty1 as the guano in even one cargo might differ4 ,in the case of the older and richer guanos1 there was certainly more uniformity in quality1 but they were liable to differ in their percentage of nitrogen4#aie ,as1 however1 the deposits became gradually worked out1 their lower layers were found more or less largely admixed with stony and earthy matter1 and their composition was naturally rendered very variable4 ,this state of matters was unsatisfactory to buyers and sellers1 and led to much friction between the two1 as it was found wellnigh impossible on the part of the seller to guarantee the composition of his manure4 ,the custom of preparing the material by reducing it to a fine powder before sending it into the market1 and the custom1 subsequently introduced1 of treating it with sulphuric acid1 have done away with this difficulty to a large extent4 ,dissolved ,guano4 ,the treatment of guano with sulphuric acid was first had recourse to in the case of cargoes damaged with water4 ,in such guano1 as has been already pointed out1 fermentation has been permitted to take place1 with the result of the formation of volatile carbonate of ammonia in greater or less quantity4 ,by the addition of sulphuric acid the ammonia was fixed1 and the guano was prevented from losing its most valuable constituent4 ,it was soon found1 however1 that guano so treated possessed greater activity as a manure4 ,the result of the sulphuric acid was to increase very materially the amount of its soluble phosphates1 and also its soluble nitrogen compounds4#aif ,it had1 moreover1 the effect of producing a guano of uniform composition4 ,the custom1 first introduced in #ahfd by ,messrs ,ohlendorff ,co41 was soon largely practised4 ,the guano is treated with #be to #cj per cent sulphuric acid 7sp4 gr4 #a4gc74 ,after a short time the resulting hard mass is1 by means of disintegrators1 reduced to a uniform powder4 ,equalised or ,rectified ,guano4 ,as guano decreased in its quality the demand for a high-class article became more and more difficult to meet4 ,this led to the custom of fortifying or rectifying--as it is variously called--the natural material with sulphate of ammonia4 ,a manure closely resembling in the percentage of its manurial constituents the older rich guanos is thus obtained4 ,of these so-called equalised guanos1 two qualities are at present sold1 the first being guaranteed to contain nitrogen equal to #h to #i per cent ammonia1 #cj to #ce per cent phosphates1 and #b to #c per cent of potash2 the second quality containing only about half as much nitrogen1 but more phosphates4 ,however valuable this fortified guano may be--and it is1 undoubtedly1 a most valuable manure--its action cannot be supposed to be exactly similar to the old ,peruvian guano1 which it resembles in the percentage of its nitrogen1 phosphates1 and potash4 ,much of the distinctive value of guano as a manure1 as will be pointed out immediately1 lies in the fact that it contains its manurial ingredients in a variety of differently soluble compounds1 which are gradually rendered available in the soil for the plant's needs4 ,this undoubtedly is one of the reasons why the action of guano among manures is quite unique2 and there are other reasons which we probably do not clearly understand4 ,however skilfully the composition of the guano may be artificially simulated1 it still remains an undoubted fact that the equalised guano is not exactly similar in its action to the genuine article4 ,nevertheless1 that it is superior in its results to the poorer classes of guano at present available1 and to ordinary compound manures1 there can be little doubt4 ,a great merit of the equalised guano is1 however1 that it is sold at a lower price than guano as imported2 and as the guano is sold on a guaranteed analysis1 the practice has done much to advance the true interests of agriculture4 ,its ,action as a ,manure4 ,next to farmyard manure1 guano may be regarded as the most general of all the commonly used manures2 for in addition to nitrogen1 phosphoric acid1 and potash1 it contains nearly all the other plant ingredients1 such as lime1 magnesia1 c4 ,its special value as a manure1 however1 does not merely consist in the amount of valuable plant-food it contains4 ,like farmyard manure1 it owes much of its characteristic action to the state of the intimate mixture of its manurial constituents1 and also1 as has already been pointed out1 to the fact that it contains those constituents in a great variety of chemical forms1 each of which differs in its solubility1 and consequently availability for the plant's needs4 ,take1 for example1 the great number of different forms of nitrogen it contains4 ,some are in the condition in which plants can immediately absorb them1 while the rest are in a series of less and less available forms1 which1 however1 are gradually converted into available forms as the plant requires them4 ,like farmyard manure1 again1 it may be applied with almost equally good results to all kinds of crops and on all kinds of soils4 ,we have in guano1 in short1 an admirable example of the value of applying our manurial ingredients in different forms4 ,that this is no mere theory is abundantly proved by the large number of different experiments which have in the past been carried out with guano1 more especially the well-known experiments made by ,grouven1 the ,german chemist4 ,in those well-known experiments1 guano was tested against a large variety of different fertilisers1 and the tests were so arranged that in most cases the amounts of nitrogen1 phosphoric acid1 and potash were the same in the other manures used4 ,in short1 these experiments prove in a very striking manner that a manure artificially made up out of most valuable fertilisers1 such as nitrate of soda1 sulphate of ammonia1 superphosphate1 c41 so as to closely resemble in its composition guano1 is by no means similar in its effects to the genuine article4 ,as in farmyard manure1 so in guano3 we must look to the complexity of the composition of both these fertilisers in order to fully estimate their worth4 ,there is in the action of both manures much that we cannot explain1 or even1 as yet1 understand4 ,the action of guano is merely one of many problems in the science of manuring which illustrate how unsatisfactory1 despite the great amount of research already carried out1 is our knowledge of this most important department of agriculture4#aig ,proportion of fertilising ,constituents in ,guano4 ,guano must be regarded as a nitrogenous and phosphatic manure1 as the quantity of potash it generally contains is small4 ,in many soils1 more especially in such a country as ,scotland1 this deficiency in potash is not of so much importance1 as the value of potash as an artificial manure is less than is the case with the other two ingredients4 ,in soils1 however1 lacking potash1 guano ought to be supplemented with some potash manure4 ,with regard to the nitrogen and phosphoric acid1 we may ask if these two constituents are in the best proportions4 ,this question does not admit of a direct answer4 ,in the first place1 the proportion in which these two ingredients are present is variable4 ,in the old rich ,peruvian guanos1 as we have above shown1 the nitrogen was more abundant than is the case at present4 ,such guanos1 it was found1 were best supplemented with phosphatic manure when applied to the field4 ,in the equalised and dissolved guanos1 which are now so largely sold1 manufacturers attempt to adjust the percentage of nitrogen and phosphoric acid to what is considered the best proportion in most cases4 ,as1 however1 we have again and again to point out1 regard must be had both to the soil and the crop in determining what is the best proportion of the manurial ingredients in a manure4 ,for cereals it may be well supplemented by nitrogenous manures1 while for roots it may be well supplemented by phosphatic manures4 ,mode of ,application4 ,like all manures1 it is desirable to apply it in as fine a condition as possible1 so as to ensure as thorough a mixture with the soil-particles as practicable4 ,in order1 furthermore1 to prevent any risk of loss through volatilisation of the ammonia1 as well as to ensure even distribution1 it is best applied mixed with dry earth1 ashes1 sand1 or some other substance1--not lime1 however4 ,the custom of applying along with the guano common salt1 has been proved by numerous experiments to be highly beneficial to the action of the guano as a manure4 ,the exact nature of the action of salt as an adjunct to manures is a point which has elicited much discussion4 ,its action is probably to be ascribed to a number of causes4 ,for one thing1 it probably acts as an antiseptic in retarding the fermentative action which has a tendency to go on so rapidly in such manures as guano4 ,it further increases the power of the manure to attract moisture from the air--a most important property in the case of drought4 ,some experiments by ,dr ,voelcker illustrate this in a striking manner4 ,two lots of guano--one pure and one mixed with salt--were exposed to the action of the air for a month1 and were then tested as to the amount of water they contained1 when it was found that the lot containing the salt had absorbed #b per cent more water than the other4 ,much stress has been laid on the importance of having the guano buried a certain depth in the soil2 and many experiments have been carried out to prove how much better it acts when so applied4 ,this is probably due to the prevention of any loss of volatile ammonia1 and the mixture of the manure with the soil-particles before it comes in contact with the plant-roots4 ,this last precaution is an important one1 for it has been found that the raw material is apt to have a bad effect on the seed or the plant's roots4 ,this has been found to be especially the case in regard to potatoes1 the quality of which has been found to suffer when the guano is brought into direct contact with the tubers4 ,as guano is a manure which is speedily available1 it is desirable to apply it as shortly before it is required by the plant as possible4 ,it is therefore generally best applied in spring1 shortly before seed-time1 or indeed at the same time4 ,where farmyard manure is used1 the guano has been recommended to be used as a top-dressing in small quantities4 ,in the majority of cases it will be advisable1 however1 not to apply it as a top-dressing1 for the various reasons above-mentioned4 ,quantity to be used4 ,as to the quantity to be used1 this of course will depend on the soil1 the crop1 and the amount and nature of the other manures employed3 #a to #d cwt4 per acre have been the usual limits1 but even heavier dressings have been commonly resorted to1 especially in ,scotland1 where #f to #h or even #i cwt4 for turnips are often used4 ,sir ,j4 ,b4 ,lawes and ,sir ,james ,caird long ago1 shortly after the introduction of guano1 estimated1 from the experiments they carried out1 that the application of #b cwt4 per acre to the wheat crop gave an increase of #h to #i bushels in grain1 and added a fourth to the quantity of straw4 ,the former authority recommends #b to #c cwt4 per acre for wheat1 to be sown broadcast and harrowed into the land before sowing the seed4 ,we have already stated that it may be used in all soils and for all kinds of crops4 ,while this is so1 it has been found to have specially favourable results when applied to the turnip crop1 when it may be used in larger quantities than in the case of cereals4 ,when applied to the turnip crop1 it is well to use the more phosphatic guanos or to supplement it with superphosphates4 ,by applying it in two lots1 the larger portion before seed-time and the rest between the drills after the turnips are up1 excellent results have been obtained4 ,it has also proved an admirable manure for mangels4 ,on the whole1 it gives best results on heavy soils and in a dampish climate4 ,adulteration of ,guano4 ,probably no artificial manure has been subjected to greater adulteration in the past than guano4 ,this has been due to the fact that the practice of selling guano on analysis--especially among retail buyers--did not largely obtain in the early years of the trade4 ,a good deal of this adulteration was probably caused by ignorant prejudice on the part of the farmer1 to whom the pungency of its smell and its colour were too apt to be ranked as its most important properties4 ,the variation in the quality of different kinds of guano was too often not sufficiently realised by the buyer1 who not unfrequently was made to pay as high a price for guano of an inferior quality as he ought to have paid for that of the best quality4 ,indeed no manure illustrates the importance of chemical analysis more than guano4 ,among the different forms of adulteration practised may be mentioned the addition of such substances as sawdust1 rice-meal1 chalk1 sulphates of lime and magnesia1 common salt1 sand1 earth1 peat1 ashes of various kinds1 and water4 ,there can be no doubt1 however1 that such adulteration has now long ceased to be practised to any extent4 ,nevertheless1 it may be of use to draw attention to one or two of the tests by means of which some of the commoner forms of adulteration may be detected4 ,one or two are extremely easily detected--as1 for example1 adulteration with sand or other mineral substances4 ,in such a case1 the percentage of ash left on burning a small portion of the guano will be found to be excessive4 ,the percentage of ash in a sample of genuine ,peruvian guano should not exceed from #ej to #fj per cent4 ,the colour of the ash is another important point1 and may serve as a further indication of adulteration4 ,in the case of genuine guano1 this should be whitish or greyish4 ,red-coloured ash generally points to the adulteration of the guano with some mineral substance containing iron--such1 e4g41 as ,redonda phosphate1 a mineral phosphate of iron and alumina4 ,where the ash is white1 but excessive in quantity1 adulteration with common salt1 sulphate of magnesia1 gypsum1 or chalk1 may be suspected4 ,the last-named substance is easily detected by treating it with any of the common acids1 when brisk effervescence1 due to the liberation of the carbonic acid1 will ensue4#aih ,a further point of importance with regard to the ash is its solubility in water and in acids4 ,a large insoluble residue may be taken as indicating adulteration with sand4 ,adulteration with water is also easily detected by heating a sample to the boiling temperature and determining the loss it sustains4 ,of course the amount of water varies in different samples4 ,the appearance of the guano will serve fairly well to detect whether it is abnormally moist4 ,it may be added1 in conclusion1 that ,peruvian guano is extremely light2 and while this by itself is not a sufficient test of genuineness1 it may serve to confirm other tests4 ,,iii4--,,so-,,called ,,guanos4 ,before concluding this chapter1 reference may be made to certain manures which are commonly known under the name of guanos--such as fish-guano1 flesh-guano1 meat-meal-guano1 and bat-guano1--as well as to manures which may more conveniently be described here--viz41 fowl and pigeon dung4 ,fish-,guano4 ,the application of fish1 not suited for other purposes1 to the fields as a manure is a practice which has obtained in certain parts of the country for a number of years4 ,in many districts on the sea-coast1 where fishing is the chief industry1 the only way in the past of disposing of a superabundant catch of herrings1 for example1 has been to utilise them as a manure4 ,from such a practice has sprung up what is now an important and ever-increasing trade--viz41 the manufacture of fish-guano4 ,this manufacture was first started1 and is still most largely practised1 in ,norway4 ,the guano obtained varies very considerably in quality according to the nature of the process employed1 and as to whether the guano is made from whole fish or merely from fish-offal4 ,the latter source is the common one4 ,the manufacture is carried on at the fish-curing stations1 and the quality of the guano made from this source is somewhat different from that made from whole fish1 as a large proportion of the fish-offal is made up of bones and heads4 ,large quantities of ,norwegian fish-guano are exported to various parts of ,europe4 ,the best quality of this guano may contain as much as #aj per cent of nitrogen1 but as a rule it is nearer #h per cent4 ,a very considerable variation in the amount of phosphoric acid occurs for the reason above stated1 the guano made from fish-scrap being naturally much richer in this ingredient than whole-fish guano4 ,the phosphoric acid may be said to range from #d to #ae per cent1 and there is also a small quantity of potash present4 ,guano is also manufactured in ,norway from the carcasses of whales4 ,such guano contains from #g-a_/b to #h-a_/b per cent of nitrogen1 and about #ac-a_/b per cent of phosphoric acid4 ,in ,america fish-guano is manufactured to a considerable extent--one important source being the menhaddo1 a coarse sort of herring4 ,this fish is caught for the sake of its oil1 which is extracted by boiling1 the residue being manufactured1 after pressing and drying1 into guano4 ,in this country the manufacture of fish-guano is carried out to a considerable and increasing extent4 ,formerly it was imported from ,norway to a larger extent than is now the case1 the present annual imports amounting only to #ajjj or #bjjj tons4 ,the total annual production in the ,united ,kingdom is probably #gjjj or #hjjj tons4 ,value of ,fish-,guano4 ,that fish-guano is a valuable manure there can be no doubt4 ,what1 however1 impairs its value is the fact that1 as a rule1 it contains a certain amount of oil4 ,the effect of this oil is to retard fermentation and decomposition when the guano is applied to the soil1 and thus render its action slower than would otherwise be the case4 ,when applied to the soil1 therefore1 every opportunity ought to be given to promote its fermentation4 ,it is best applied some time before it is likely to be used4 ,it ought to be well mixed with the soil-particles1 and not allowed to lie on the top of the soil4 ,its best effect will be on light well-cultivated soils1 which permit of the access both of sufficient moisture and of sufficient air for rapid fermentation4 ,its value as a manure for hops1 vines1 grass1 and strawberries has been found to be considerable4 ,it has been recommended to be applied along with farmyard manure2 and such a mode of application is no doubt well suited to promote its decomposition4 ,it has also been used for mixing with superphosphate of lime4 ,professor ,storer has advocated a more general use of fish as a manure than is at present the case4 ,he suggests that even fish not suitable for edible purposes might be caught for the purpose of conversion into manure4 ,the difficulty of preserving fish1 however1 is considerable2 and he suggests the use of potash salts1 such as muriate of potash1 or lime for this purpose4 ,the benefit of using potash would be twofold4 ,in addition to acting as a preservative1 it would considerably enhance the value of the resulting guano as a manure4 ,there is much truth in ,professor ,storer's views2 and no doubt1 as our sources of artificial nitrogenous manures grow more limited1 the manufacture of fish-guano will be carried on in the future on a larger and more systematic scale than hitherto4 ,meat-meal ,guano4 ,what is called meat-meal guano is generally that made from the refuse of the carcasses of cattle after they have been treated for their meat-extract according to ,liebig's process4 ,the meat-meal is used both for feeding and manurial purposes4 ,considerable quantities#aii of this guano are imported annually into this country from ,south ,america1 ,queensland1 and ,new ,zealand1--that coming from ,frey ,bentos1 in ,uruguay1 being best known4 ,it is a valuable manure1 especially so for its nitrogen1 which varies from #d to #h per cent1 while it contains of phosphoric acid from #ac to #bj per cent4 ,some meat-meal guanos contain as much nitrogen as #aa per cent4 ,in some parts of the world1 more especially in ,germany1 the carcasses of horses1 as well as cattle1 dogs1 pigs1 c41 which have died of disease1 are converted into a guano4 ,they are subjected to treatment by steam in digestors1 by which means the fat and gelatine are separated and utilised1 while the remaining portion of the animal is converted into guano4 ,other processes are also employed4 ,the resulting manure contains from #f to #aj per cent of nitrogen1 and from #f to #ad per cent of phosphoric acid4 ,value of ,meat-meal ,guano4 ,meat-meal guano is a valuable nitrogenous manure4 ,the same remarks apply to it as to fish-guano1 although it ferments probably very much more quickly than the latter1 and is undoubtedly a more valuable manure4 ,bat ,guano4 ,in conclusion1 we may consider bat guano4 ,bat guano1 which is really a very rare curiosity1 has been found accumulated in hot climates in caves4 ,the samples which have been analysed have differed very much in quality1 some containing as much as #i per cent of nitrogen and #be per cent of phosphoric acid4 ,provided it could be obtained in any quantity1 and of a quality even approximating to the above analysis1 it need scarcely be pointed out that bat guano would be a most valuable manure4 ,a singular point about its composition is1 that it has been found to contain a considerable proportion of its nitrogen 7as much as #c per cent7 in the form of nitrates4 ,pigeon and ,fowl ,dung4 ,pigeon dung is a manure which historically is of great importance4 ,the dung of pigeons was used as a manure by the ancient ,romans2 and even in modern times1 more especially in ,france1 it was considered a most important fertiliser4 ,despite these facts1 pigeon dung is by no means a rich manure1 and its composition compares most unfavourably with that of the guanos we have just been considering4 ,according to ,storer1#bjj it only contains from #a-a_/d to #b-a_/b per cent of nitrogen1 and from #a-a_/b to #b per cent of phosphoric acid1 and a little over #a per cent of potash4 ,the dung of poultry is just about as poor1 fowl dung containing from 4#h to #b per cent of nitrogen1 #a-a_/b to #b per cent of phosphoric acid1 and a little under #a per cent of potash2 while that of ducks and geese is even poorer4#bja ,from these statements it will be seen that the excrements of pigeons1 hens1 and ducks do not form a rich manure4 ,one thing about pigeon dung which is to be noticed1 is the fact that it ferments very quickly4 ,none of the pseudo-guanos1 however rich they may be in manurial ingredients1 can be regarded as equal in their action to the genuine article1 for reasons which we have gone into already when considering the action of guano4 ,,footnotes3 #ahc ,bones1 it is true1 were in use long before guano2 but popular as they deservedly were1 they had not been used1 at the time of the importation of guano1 to any very considerable extent4 #ahd ,the total annual imports at present may be taken at under #cj1jjj tons1 whereas in #ahee they amounted to over #bjj1jjj tons4 ,for statistics on this point the reader is referred to the ,appendix1 ,note ,i41 p4 #cbg4 #ahe ,with regard to the origin of certain guano deposits1 which are of very recent date--e4g41 ,angamos and ,ichaboe--there can be no doubt whatever1 because we can witness the process of formation still taking place4 ,it is not so1 however1 with regard to older deposits1 for which some have been inclined to claim mineral origin4 ,the best proof that such deposits owe their origin mainly to bird excrements is the comparatively large quantity of uric acid they contain4 ,on the other hand1 the evidence in support of the belief that they are also formed from the remains of the birds themselves and other animals1 is to be found in the large proportion of phosphates they contain1 and the presence in the deposits of feathers and the fossilised skeletons of the animals above mentioned4 #ahf ,a complete list of the various deposits will be found in the ,appendix1 ,note ,,ii41 p4 #cbg4 ,it may be noticed that nearly all the deposits lie within #aj deg4 to #bj deg4 north and south of the ,equator4 #ahg ,see ,chapter on ,farmyard ,manure1 p4 #beg4 #ahh ,according to ,nesbit1 some of the cargoes of this guano contained hard saline lumps of very little manurial value--over #ej per cent being common salt4 #ahi ,the salt exports were made in #ahfh4 #aij ,for analyses of these nodules and crystals1 see ,appendix1 ,note ,,iii41 p4 #cbh4 #aia ,see ,heiden1 vol4 ii4 p4 #cef4 #aib ,see ,appendix1 ,note ,,iv41 p4 #cbi4 #aic ,the ,ichaboe guano at present exported is a fresh deposit1 and is annually collected for shipment4 #aid ,further chemical changes have occurred in certain cases between the guano and the limestone rock beneath1 resulting in the formation of what is called a crust guano4 ,such guanos form a soft phosphatic rock1 and are extremely rich in phosphates4 ,as examples of these crust guanos may be mentioned ,sombrero1 ,curacao1 ,aruba1 ,mexico1 and ,navassa phosphates4 #aie ,the presence in the old ,peruvian guano of concretionary nodules has already been referred to4 #aif ,according to ,vogel the nitrogen as urates is converted by the sulphuric acid into ammonia salts4 #aig ,see ,appendix1 ,note ,,vi4 p4 #ccj4 #aih ,it must be remembered1 however1 that even genuine guano contains a certain quantity of carbonate of lime1 and will give a slight amount of effervescence when so treated4 #aii ,the annual imports may be stated at from #cjjj to #djjj tons4 #bjj ,agricultural ,chemistry1 vol4 i4 p4 #cfg4 #bja ,see ,appendix1 ,note ,,vii41 p4 #cca4 ,,appendix ,,to ,,chapter ,,viii4 ,,note ,i4 7p4 #big74 ,,peruvian ,,guano ,,imported ,,into ,,the ,,united ,,kingdom1 #ahfe-ahic4 ,year4 ,tons4 ,year4 ,tons4 #ahfe #bac1jbd #ahha #cc1cic #ahgj #bdg1jbh #ahhb #bg1chb #ahga #add1gce #ahhc #cf1gac #ahgb #gd1ifd #ahhd #ae1hjb #ahgc #ace1hie #ahhe - #ahgd #id1cdf #ahhf #bh1gcc #ahge #hf1jdb #ahhg #e1ghd #ahgf #aeh1fgd #ahhh #af1ddf #ahgg #aaa1hce #ahhi #ag1jjj #ahgh #abg1hac #ahij #ai1jjj #ahgi #de1dge #ahia #aa1jjj #ahhj #eh1fca #ahib #ad1jjj ,,note ,,ii4 7p4 #bih74 ,,guano ,,deposits ,,of ,,the ,,world4 ,,south ,,america-- ,peru4--,in various islands off the coast--viz41 ,chincha1 ,guanape1 ,ballestas1 ,macabi1 ,lobos1 and ,patillos2 and on different parts of the coast--viz41 ,pabellon de ,pica1 ,chipana1 ,huanillos1 ,punta de ,patillos1 ,independence ,bay1 and ,lobos de ,afuera4 ,columbia4--,in different parts of the ,states of ,venezuela1 ,new ,granada1 and ,ecuador4 ,guano coming from these parts is often known as ,columbian guano1 or according to the name of the ,state in which it is found4 ,maracaibo and ,monks guanos come from the coast of ,venezuela4 ,deposits are also found on the ,galapagos ,islands1 to the west of ,ecuador4 ,bolivia4--,mejillones1 ,patagonia1 ,leon's4 ,,north ,,america--,deposits have been found on the coasts of ,mexico and ,california2 on the ,raza and ,patos ,islands2 and on the coasts of ,labrador4 ,they have also been found on the ,islands of ,curacao1 ,aruba1 and ,navassa in the ,gulf of ,mexico4 ,,africa--,on the west coast deposits have been found at ,algoa ,bay1 ,saldanha ,bay1 and on the ,island of ,ichaboe4 ,,australia--,shark's ,bay and ,swan ,island4 ,,west ,,indies--,sombrero1 ,aves1 and ,cuba4 ,,pacific ,,ocean--,on the ,islands of ,baker1 ,jarvis1 ,howland1 ,malden1 ,starbuck1 ,fanning1 ,enderbury1 ,lacepede1 ,browse1 ,huon1 and ,surprise4 ,,asia--,deposits at ,kuria ,muria on the ,arabian coast1 and on the ,sandwich ,islands4 7,see ,heiden's ',duengerlehre1' vol4 ii4 p4 #cdi47 ,,note ,,iii4 7p4 #cjc74 ,,composition ,,of ,,concretionary ,,nodules4 7,analyses by ,karmrodt47 ,no4 #a4 ,potassium sulphate #g4di phosphate #i4eb ,sodium #i4jh ,ammonium #g4eg ,calcium sulphate #c4dj ,ammonium urate #d4ji oxalate #da4bh ,nitrogenous organic matter #aj4ag ,water #g4dj ----- #ajj4jj ------ ,nitrogen #ad4hd ,no4 #b4 ,potassium sulphate #de4fd ,sodium #ac4bb ,ammonium #aj4bc oxalate #i4ad ,basic ammonium phosphate #ab4ji ,precipitated ammonium phosphate #d4gh ,organic matter 4#id ,insoluble #a4ij ,water #b4jf ------ #ajj4jj ------ ,,note ,,iv4 7p4 #cjf74 ,the following analyses1 being the average of a large number of different samples analysed from time to time in the chemical laboratory of the ,pommritz ,agricultural ,experimental ,station1 show the gradual deterioration of ,peruvian guano1 as regards its percentage of nitrogen1 during the years #ahfg-ha3-- ,nitrogen4 ,nitrogen4 #ahfg #ac4af #ahgc #i4af #ahfh #aa4ih #ahgd #i4hc #ahfi #ac4ff #ahgh #g4aj #ahgj #ab4cg #ahgi #f4ie #ahga #aj4jd #ahhj #g4jg #ahgb #aj4gb #ahha #f4ic ,,note ,v4 7p4 #cji74 ,,composition ,,of ,,different ,,guanos4 ,the following is a list of the more common nitrogenous and phosphatic guanos which have been used in the past or are at present in use4 ,those printed in italics are still being worked4 ,as their value depends on their nitrogen and phosphoric acid1 these alone have been given4 ,the percentages must be taken as mere approximations1 as the quality of different cargoes from the same deposits varies very much4 ,the table may be found useful for reference4 ,nitrogenous ,guanos4 ,phosphoric ,tricalcic ,nitrogen ,ammonia4 acid phosphate4 per cent4 per cent4 per cent4 per cent4 ,angamos #bj #bd #e #aa ,chincha #ad #ag #ac #bh ,ballestas #ab #ae #ab #bf ,egyptian #aa #ac #ai #da ,guanape #aa #ac - - ,macabi #aa #ac #ab #bf ,corcovado #aa #ac #ae #cc ,saldanha ,bay #i #aa #i #bj ,ichaboe #h #aj #i #bj ,independence ,bay #g #i #ab #bf ,pabellon de ,pica #g #i #ad #ca ,punta de ,lobos #d #e #ae #cc ,huanillos #f #g #ah #bh ,penguin #e #f #aa #bd ,patagonian #d #e #ah #ci ,falkland ,islands #d #e #ad #ca ,phosphatic ,guanos4 ,phosphoric ,tricalcic acid phosphate4 per cent4 per cent4 ,maracaibo1 or ,monks #db #ib ,raza ,island #dj #hg ,curacao #dj #hg ,baker ,island #ci #he ,starbuck #ch #hc ,enderbury #cg #ha ,californian #ce #gf ,aves #cd #gd ,fanning ,island #cd #gd ,howland #cd #gd ,sidney ,island #cd #gd ,mejillones #cc #gb ,lacepede ,island #cc #gb ,malden ,island #cb #gj ,sombrero #cb #gj ,browse ,island #ca #fh ,huon ,island #bh #fa ,patos ,island #bd #eb ,jarvis ,island #bj #dd ,cape ,vert #aa #bd ,,note ,,vi4 7p4 #cad74 ,it may be of interest to refer to a theory put forward by ,liebig as to the action of oxalic acid in guano4 ,this1 he considered1 had the effect of gradually rendering the insoluble calcium phosphate soluble1 and giving rise to the formation of ammonium phosphate and calcium oxalate4 ,such an action would probably take place were the guano allowed to ferment by itself4 ,we know1 however1 that when it is brought in contact with the soil-particles1 all its soluble phosphate is converted into precipitated phosphate4 ,,note ,,vii4 7p4 #cbf74 ,,analyses ,,of ,,dung ,,of ,,fowls1 ,,pigeons1 ,,ducks1 ,,and ,,geese4 7,storer's ',agricultural ,chemistry1' vol4 i4 p4 #cfg47 ,fowls4 ,pigeons4 ,ducks4 ,geese4 ,water #ef4jj #eb4jj #ef4fj #gg4aj ,organic matter #be4ej #ca4jj #bf4bj #ac4dj ,nitrogen #a4fj #a4ge #a4jj 4#ee ,phosphoric acid #a4e-b4jj #a4e-b4jj #a4dj 4#ed ,potash 4#hj-4ij #a4j-a4be 4#fb 4#ie ,lime #b4jj-b4ej #a4e-b4jj #a4gj 4#hd ,magnesia 4#ge 4#ej 4#ce 4#bj ,according to a computation by a ,belgian farmer1 a pigeon yields about #f lb4 of dung in a year1 a hen about #ab lb41 a turkey or goose about #be lb41 and a duck #ah lb4 ,,chapter ,,ix4 ,,nitrate ,,of ,,soda4 ,nitrate of soda1#bjb or1 as it is more correctly designated from a chemical point of view1 sodium nitrate1 now forms the chief artificial nitrogenous manure in use4 ,along with sulphate of ammonia1 it has taken the place once held in the manure markets by the older ,peruvian guano1 and may without doubt be reckoned1 at present prices1 one of the cheapest and most valuable of the artificial sources of nitrogen for the plant4 ,it is some sixty-two years ago since it was first exported from ,south ,america into this country4 ,the total exports in that year amounted to about #hjj tons1 and some indication of the enormous extent to which the use of this valuable fertiliser has been developed since then will be obtained from the statement that the total exports at present amount to little less than #a1jjj1jjj tons per annum1 representing a monetary value of #f to #g millions sterling4 ,of this quantity about #abj1jjj tons are imported into ,britain4#bjc ,while its chief use is for manurial purposes1 it must not be imagined that it is only used for this purpose4 ,a certain amount is used in connection with various chemical manufactures--for instance1 that of nitric and sulphuric acid--and also in the manufacture of saltpetre1 the chief constituent of gunpowder4 ,date of ,discovery of ,nitrate ,deposits4 ,the exact date of the discovery of the nitrate deposits seems to be a point of considerable dubiety4 ,the earliest published description of them was written by ,bollaert about the year #ahbj1 in which year1 it is stated1 the first shipment was made to ,england4 ,it was not1 however1 till some ten or twelve years later that the ,peruvian ,government1 to whom they then belonged1#bjd seems to have recognised their value4 ,the most important deposits are found in the vicinity of the town of ,iquique1 which is the chief nitrate port of ,south ,america4 ,it is a somewhat striking fact that this substance1 which has conclusively proved itself to be the most potent of all known artificial agents in the promotion of vegetable growth1 should be found in a district utterly lacking the slightest traces of vegetation of any kind4 ,lest such a statement should seem to savour of irony1 we hasten to explain that the singular barrenness of this part of the country is largely due to the character of its climate1 the deposits occurring in the midst of sandy deserts1#bje on which rain never falls4 ,their ,origin4 ,the origin of these nitrate-fields is a geological problem of very considerable interest1 the difficulty of which is greatly enhanced by their altitude--#cjjj to #djjj feet above the sea-level--and their distance inland1 which amounts in some cases to eighty or ninety miles from the sea-coast4 ,the nitrate deposits are not the only saline deposits found in ,chili4 ,according to the late ,david ,forbes1#bjf they are not to be confused with other saline formations1 which appear at intervals scattered over the whole of that portion of the western coast1 on which no rain falls4 ,the latter stretch from north to south for a distance of more than #eej miles--their greatest development being between latitudes #ai deg4 and #be deg4 south4 ,the depth to which they extend downwards varies considerably4 ,most of them1 however1 are of a very superficial character1 and they always show signs of their existence by the saline efflorescence seen on the surface of the ground1 which often covers vast plains as a white crystalline incrustation1 the dust from which1 entering the nostrils and mouth of the traveller1 causes much annoyance1 whilst at the same time the eyes are equally suffering from the intensely brilliant reflection of the rays of a tropical sun4 ,these saline incrustations1 or salinas1 as they are generally called1 are chiefly composed of salts of lime1 soda1 magnesia1 alumina1 and of boracic acid4 ,their composition would lead one to attribute their origin to the evaporation of salt water2 for1 with the single exception of boracic acid1#bjg all the mineral substances are such as would be obtained by the evaporation of sea-water1 or by the mutual reactions of its salts with the constituents of the adjacent rocks4 ,as there is indisputable evidence of the recent elevation of the whole of this coast1 volcanic upheaval might be reasonably held to explain their altitude4 ,their comparative proximity to the coast would seem further to favour this theory4 ,on these grounds1 therefore1 ,forbes is inclined to think that they owe their origin to the evaporation1 under the influence of a tropical sun1 of lagoons of salt water1 the communication of which with the sea had been cut off by the rising of the land4 ,forbes and ,darwin on the ,theory of their ,origin4 ,the obvious difficulty of accounting for the formation of the larger deposits by such a theory he meets by saying that it is only necessary to suppose that1 even after the partial isolation of the lagoons by the elevations of the coast1 they might still have maintained tidal or occasional communication with the sea by means of lateral openings in the chain of hills separating them from the ocean4 ,in such cases there would be a gradual accumulation of salts1 very much greater in amount than that due simply to the evaporation of the water originally contained in the lagoons4 ,the above theory of the origin of the lower saline deposits may go to explain the mode of formation of the nitrate-fields2 but in this case several difficulties present themselves4 ,one is the much greater altitude of the latter1 as well as their greater distance inland4 ,this difficulty1 however1 may be met by assuming that they are of older origin than the lower deposits1 and have been subjected to a correspondingly greater amount of volcanic upheaval4 ,there is abundance of proof that this part of the continent has been the scene in the past of such volcanic upheaval4 ,forbes is of opinion that there is the fullest evidence to prove that1 even since the arrival of the ,spaniards1 a very considerable elevation of the land has taken place over the greater part1 if not the whole extent1 of the line of coast2 while ,darwin states that he has convincing proof that this part of the continent has been elevated from #djj to #abjj feet since the epoch of existing shells4 ,furthermore1 elevations of the coast-line1 amounting in many cases to several feet1 are known to have happened within recent times1 while earthquakes and volcanic disturbances of a less striking nature are still of common occurrence4 ,successive lines1 indicative of old sea-beaches1 can be distinctly traced stretching inland1 one behind the other2 and patches of sea-sand and water-worn stone1 found at a great distance from the coast1 both in valleys and at altitudes much greater even than #djjj feet1 point to the same conclusion4#bjh ,the difficulty1 therefore1 of altitude and distance from the coast cannot be regarded as insuperable4 ,source of ,nitric ,acid4 ,a difficulty1 however1 which is not so easily met1 is afforded by the presence of the nitric acid which1 in combination with the soda1 forms the nitrate of soda4 ,it is scarcely necessary to inform our readers that nitrogen--except1 of course1 in small quantities in the free state--is not a normal constituent of salt water4 ,the question1 therefore1 of greatest interest in connection with the formation of these nitrate-beds is1 ,whence has the nitric acid been derived8 ,several theories have been put forward to account for it4 ,guano ,theory4 ,one is to the effect that it owes its origin to huge guano deposits1 originally covering the shores of the large salt lakes which1 by the subsequent overflowing of their shores1 effected the mixture of the guano with the salts4 ,in this way1 by a slow process of decomposition1 nitrate of soda would be ultimately formed4#bji ,this theory1 apart from other considerations1 seems at first sight extremely plausible1 more especially when we remember that it is on this very coast that the greatest guano deposits have been found1 and that the famous ,chincha ,islands1 which alone have yielded over #aj million tons of this valuable fertiliser1 are comparatively near the scene of the nitrate deposits4 ,what seems further to support this theory1 is the actual occurrence in the nitrate-fields themselves of small quantities of guano4 ,but however plausible it may appear at first sight1 it does not bear closer criticism4 ,one very serious objection is the absence in these deposits of phosphate of lime1 which is the largest constituent of guano4 ,if they were really due to guano1 how does it happen that the insoluble phosphate of lime should have disappeared1 while the easily soluble nitrate of soda should alone be preserved8 ,again1 assuming this theory to be correct1 we should naturally expect to be still able to find evidence of the chemical changes which would under such circumstances have taken place1 in the shape of portions of the guano in the transition stage4 ,such evidence1 however1 the most careful investigations have failed to detect4 ,apart1 however1 from the above objections1 there seems to be little doubt1 from evidence afforded by traces of birds' nests1 c41 that the guano found in the nitrate-beds was deposited subsequent to the formation of the nitrate of soda4 ,nitric ,acid derived from ,sea-weed4 ,the most probable theory seems to be that put forward by ,noellner4 ,the origin of the nitric acid is1 according to him1 to be ascribed to the decay of great masses of sea-weed1 which1 by means of hurricanes such as are still prevalent in these districts1 were driven into the lagoons4 ,the chief difficulty in the way of accepting this theory is the enormous quantity of sea-weed required to produce the millions of tons of nitric acid these deposits contain4 ,it must be remembered1 however1 as bearing upon this point1 that the occurrence of gigantic masses of sea-weed in the ,pacific ,ocean#baj is by no means uncommon even at the present time4 ,if1 to understand the formation of coal1 we must suppose the ,carboniferous period to be one during which exceptionally luxuriant growth of vegetation took place1 we may be permitted to suppose a similar luxuriant growth of sea-weed during the formation of the nitrate deposits4 ,very strong confirmation of the truth of this theory is further afforded by the presence in large quantities1 in the raw nitrate of soda1 of iodine1 a substance characteristic of sea-weed2 while pieces of sea-weed still undecomposed are met with here and there4 ,on the whole1 therefore1 this theory1 while not free from difficulties1 seems to be the most worthy of acceptance as regards the origin of the nitrate deposits4#baa ,appearance of ,nitrate-fields4 ,having thus discussed the origin of the nitrate-fields1 we may now give a more detailed description of their appearance4 ,the chief deposits at present being worked are those lying in the ,pampa de ,tamarugal1 in the province of ,tarapaca4 ,they stretch to a distance of thirty or forty miles inland1 from ,pisagua southwards to somewhat beyond the town of ,iquique4 ,this huge desert1 as has been already indicated1 seems to be entirely destitute of all vegetation and animal life4 ,even in the immediately adjoining country the only kind of vegetation that seems to grow is a species of acacia4 ,the few streams that are found in this neighbourhood are entirely fed by the melting snow from the ,cordilleras4 ,darwin describes the appearance presented by these pampas as resembling a country after snow1 before the last dirty patches are thawed4 ,the caliche1 or raw nitrate of soda1 is not equally distributed over the pampas4 ,the most abundant deposits are situated on the slopes of the hills which probably formed the shores of the old lagoons4 ,an expert can tell from the external appearance of the ground where the richest deposits are likely to be found4 ,the caliche itself is not found on the surface of the plain1 but is covered up by two layers4 ,the uppermost1 known technically as chuca1 is of a friable nature1 and consists of sand and gypsum2 while the lower1 the costra1 is a rocky conglomerate of clay1 gravel1 and fragments of felspar4 ,the caliche varies in thickness from a few inches to #aj or #ab feet1 and rests on a soft stratum of earth called cova4 ,the ,method of mining the ,nitrate4 ,the mode in which the caliche is excavated is as follows3 ,a hole is bored through the chuca1 costra1 and caliche layers till the cova or soft earth is reached below4 ,it is then enlarged until it is wide enough to admit of a small boy being let down1 who scrapes away the earth below the caliche so as to form a little hollow cup4 ,into this a charge of gunpowder is introduced1 and subsequently exploded4 ,the caliche is then separated by means of picks from the overlying costra and carried to the refinery4 ,composition of ,caliche4 ,both in appearance and composition it varies very much4 ,in colour it may be snow-white1 sulphur1 lemon1 orange1 violet1 blue1 and sometimes brown like raw sugar4 ,the caliche found in the ,pampa de ,tamarugal contains generally about #cj to #ej per cent pure nitrate of soda2 that in the province of ,atacama contains from #be to #dj per cent4 ,the subsequent refining processes1 which consist in crushing it by means of rollers and then dissolving it1 need not here be described4 ,it may be sufficient to mention that the process used is that known as systematic lixiviation1 and is analogous to the method introduced by ,shanks in the manufacture of soda4 ,the chief impurity in the raw material is common salt3 gypsum1 sulphates of potassium1 sodium1 and magnesium1 along with insoluble matters1 are the other impurities4 ,the manufacture of iodine1 which1 as has been already noticed1 is found in the nitrate-beds1 is also carried on at these oficinas4 ,extent of the ,nitrate ,deposits4 ,the question of the extent of the nitrate of soda deposits is naturally one of very great interest1 especially from the agricultural point of view4 ,m4 ,charles ,legrange1 a ,french writer1 estimated a few years ago that they still contained about #ajj1jjj1jjj tons of pure nitrate of soda4 ,opinions on this point differ very considerably1 and it seems wellnigh impossible to arrive at any very accurate estimate4 ,the number of years they will last will depend1 of course1 on the amount of annual exportation4 ,this1 at present1 falls little short of #a1jjj1jjj tons4 ,if this amount is maintained1 they should last1 according to experts1 some twenty or thirty years at least4 ,a consideration which has an important influence on this question1 is the price obtained for the article4 ,if this should be increased1 it may be possible to treat the larger quantities of the inferior raw material 7which at present prices are allowed to accumulate7 at a profit4 ,undoubtedly this is what will ultimately take place1 when the richer quality of the caliche has been exhausted4 ,composition and ,properties of ,nitrate of ,soda4 ,as has already been pointed out1 commercial nitrate of soda contains about #ie per cent of pure nitrate of soda1 or about #ae-a_/b per cent of nitrogen1 which1 if calculated as ammonia1 would equal #ai per cent4 ,it is1 next to sulphate of ammonia 7which contains #bd-a_/b per cent of ammonia71 the most concentrated nitrogenous manure1 and further1 contains its nitrogen in the form most readily available for the plant's use4 ,its most characteristic property is its great solubility1 and consequent speedy diffusion in the soil1 and the inability of the soil-particles to fix its nitrogen4 ,in the latter respect it differs very considerably from other forms of nitrogen4 ,ammonia salts1 though practically quite as soluble1 do not diffuse in the soil so rapidly as nitrate of soda does2 for the ammonia is more or less tenaciously fixed by the soil-particles1 and retained till converted by the process of nitrification into nitrates4 ,nitrate of ,soda applied as a ,top-dressing4 ,on this account nitrate of soda is chiefly employed--and rightly so--as a top-dressing4 ,the risk of loss by drainage is thus minimised1 and the valuable nitrogen finds its rightful destination--viz41 in the plant's roots4 ,encourages deep ,roots4 ,a special benefit which the diffusibility of nitrate of soda has been held to confer on the plant1 is to encourage the growth of deep roots1 by inducing the growing plant to send down its roots into the lower layers of the soil after the nitrate of soda4 ,the benefit of deep roots is1 of course1 very great4 ,they enable the plant to withstand the action of drought1 and at the same time increase the area whence the plant may derive its nourishment4 ,although the value of the manure is practically entirely due to the nitrogen it contains1 it has been urged that the soda exercises a beneficial effect on the mechanical properties of the soil1 by increasing its power of absorbing moisture1 and in also rendering it more compact4 ,this would partly explain how its results in dry seasons are so much better than those obtained from sulphate of ammonia4 ,this mechanical action of nitrate can scarcely be very great when we remember the comparatively small quantity applied4 ,even in the driest of seasons there will always be sufficient moisture to secure the diffusion of the nitrate of soda1 while the risk of loss by drainage will be reduced to a minimum4 ,much ignorance1 as well as prejudice1 has existed in the past as to the true nature of the action of nitrate of soda4 ,nor is this prejudice even yet entirely dispelled4 ,is ,nitrate an exhausting ,manure8 ,the common charge brought against it is1 that it is what has been termed an exhausting manure4 ,this objection1 to have any weight1 must mean that nitrate of soda produces a crop which takes out of the soil an abnormal quantity of fertilising matter4 ,but1 so far as the writer is aware1 no scientific evidence has ever been brought forward to support this contention4 ,that the indiscriminate use of a manure may produce a crop in which the stem and leaves are unduly developed at the expense of the grain1 or in which the quality of the crop may suffer from too rapid growth1 is1 of course1 a well-known fact4 ,but as this could also be produced by an overdose of soluble phosphoric acid as well as ammonia salts1 it is not a property that belongs exclusively to nitrate of soda4 ,probably nitrate of soda has in the past been often used in this indiscriminate way so as to produce such results4 ,the fault1 therefore1 lies not in the manure1 but in the mode of its application4 ,a few remarks1 therefore1 on this most important subject may prove serviceable4 ,crops for which it is suited4 ,opinions will naturally differ as to the crops to which it is profitable to apply nitrate of soda4 ,its value as a manure for cereals is pretty generally admitted4 ,its value as a manure for roots is not1 however1 so universally admitted4 ,experiments would seem to show that such a crop as the mangold derives just as much benefit as do the cereals2 while in ,germany practical experience on a very large scale has demonstrated its value as a manure for beetroots4 ,it may be generally recommended as a manure for all crops1 except1 perhaps1 the so-called leguminous crops1 such as clover1 beans1 peas1 c1 whose ability to obtain nitrogen for themselves renders the application of expensive artificial nitrogenous manures unadvisable4 ,an interesting point with regard to nitrate of soda is the curious effect it seems to have on the colour of the leaves of plants4 ,this interesting fact has been strikingly demonstrated at the ,rothamsted ,experimental ,station1 in the contrast in the colour of the leaves of different experimental grass-plots1 manured with nitrate of soda and sulphate of ammonia respectively--the plots manured with nitrate of soda being distinctly darker in hue1 obviously owing to the greater production of chlorophyll or green matter4 ,such a depth of colour would seem to indicate a more healthy development4 ,method of ,application4 ,while opinions1 therefore1 will naturally differ as to the crops to which nitrate of soda will be most profitably applied1 little difference of opinion exists as to the method of its application4 ,the inability of the soil-particles to retain it1 the frequency of rain1 the costly nature of the manure itself1 and its immediate availability as a plant-food1 all point to the extreme advisability of using it as a top-dressing4 ,even when used as a top-dressing1 it may be advisable not to apply the entire quantity all at one time4 ,by applying it in instalments1 little risk is run that1 through inclemency of weather1 the manure will be lost4 ,another point of importance in applying nitrate of soda is to secure uniform distribution4 ,this of course is applicable to all artificial manures1 but in a very special degree to nitrate of soda1 because of its great value and the comparatively small quantity applied4 ,as the uniform distribution of one cwt4 of any material over an acre of soil is by no means an easy task1 the mixing of nitrate of soda with some diluent1 such as dry loam1 is consequently highly advisable4 ,common salt is often applied along with nitrate of soda4 ,the indirect value of salt as a manure is considerable1 and when applied along with nitrate1 ensures its more speedy diffusion in the soil1 by increasing the soil's capacity for absorbing moisture from the air4 ,must be a ,sufficiency of other ,fertilising ,constituents4 ,a third point of importance in applying nitrate of soda1 is to see that the soil is sufficiently supplied with the other plant-foods--phosphates and potash4 ,this is a sine qua non1 if the nitrate is to get a fair chance4 ,if it is desired to apply nitrate of soda along with superphosphate of lime1 a word of caution is necessary against making the mixture long before it is used4 ,the reason of this is1 that a chemical action is apt to ensue1 resulting in the loss of the nitric acid in the nitrate of soda4 ,the nature of the soil is another important consideration to be taken into account4 ,in the case of extremely loose and sandy soils1 it is scarcely to be recommended as the most suitable form in which to apply nitrogen4 ,if applied to such soils1 especial care ought to be taken to minimise risk of loss4 ,no hard-and-fast rules can be laid down as to the quantity in which it ought to be applied4 ,this must be regulated very much by the crop1 the nature of the soil1 and the quantity of other manures employed4 ,from #a to #a-a_/d cwt4 may be recommended as a suitable quantity for corn crops which are otherwise liberally manured4 ,on strong clay soils this quantity may be judiciously increased up to #b cwt4 ,dr ,bernard ,dyer1 who has experimented largely on its use as a manure for mangolds1 is of opinion that an application of from #c to #d cwt4 an acre is likely to prove thoroughly profitable2 and the present writer has found in his experiments with turnips that a top-dressing of #a cwt4 amply repaid itself4 ,conclusions drawn4 ,in conclusion1 the nature and characteristics of nitrate of soda as a manure may be briefly summed up as follows3-- #a4 ,it is a whitish1 crystalline salt1 extremely soluble1 and is quickly diffused in the soil4 ,it should contain #ie per cent of pure nitrate of soda--i4e41 #ae-a_/b per cent of nitrogen1 equal to about #ai per cent of ammonia4 #b4 ,next to sulphate of ammonia1 it is the most concentrated nitrogenous manure2 the relative quantities of nitrogen these two manures contain being as three is to four4 #c4 ,it contains its nitrogen in the most valuable and readily assimilable form--i4e41 as nitric acid1 the form into which all other forms of nitrogen have first to be converted before they become available for the plant's uses4 #d4 ,that1 at present market prices1 nitrate of soda may be safely affirmed to be the cheapest form of nitrogenous manure4 #e4 ,that nitrate of soda1 in addition to its direct value as a manure1 probably exercises a slight influence on the mechanical properties of the soil1 by increasing its compactness and water-absorbing capacities2 that it further tends to promote deep roots1 and thus to increase the soil area whence the plant may derive its nourishment1 at the same time rendering the plant more able to withstand the injurious influence of drought4 #f4 ,that a plentiful supply of the other manurial constituents should be present in the soil1 if nitrate of soda is to exercise its full value4 #g4 ,that it may be profitably applied in the case of nearly all kinds of crops1 but that great care should be taken as to the mode of its application4 ,that this should be almost invariably as a top-dressing1 and that it should be applied in several doses if possible4 #h4 ,that its effects can be regarded as lasting only during the first year after application4 ,,footnotes3 #bjb ,this substance is also largely known under the name ,chili saltpetre1 to distinguish it from potassium nitrate or common saltpetre4 #bjc ,see ,appendix1 p4 #cea4 #bjd ,we may remind our readers that these nitrate deposits were largely the cause of the late war between ,chili and ,peru1 which resulted in the cession to ,chili by ,peru of the province of ,tarapaca1 where the most important deposits are situated4 #bje ,the other nitrate deposits are found in the provinces of ,antofagasta and ,atacama1 and a certain amount of the refined article is exported from these places4 ,the amount1 however1 is inconsiderable as compared with that which comes from the province of ,tarapaca4 #bjf ,see his elaborate article on the ,geology of ,bolivia and ,peru1 published in the ',quarterly ,journal of the ,geological ,society' for ,november #ahfj4 #bjg ,the source of the boracic acid is probably volcanic4 #bjh ,a friend of the present writer1 who has visited this part of the west coast of ,south ,america1 informs him that at one point of the coast at ,mejillones 7in ,bolivia7 he could trace the remains of no fewer than twelve distinct sea-beaches1 situated at different distances from the sea1 and rising to an altitude of #bejj feet4 #bji ,in this change1 lime derived from the sea-shells would play an important part4 ,modern researches have shown1 as we have already said in a previous chapter1 that1 in the conversion of organic nitrogen into nitrates1 the presence of carbonate of lime is a necessary condition4 #baj ,the ,gulf weed is an instance in point4 ,huge masses of floating sea-weed are sometimes found1 #ejj to #fjj miles in length1 forming the so-called ,saragossa ,sea4 #baa ,a difficulty which has not been referred to is the belief entertained by geologists that there has been a change of climate in ,northern ,chili1 and that there must have been more rain there formerly than there is at present4 ,traces of human habitations are found high up in the ,cordilleras to-day4 ,cobs of ,indian corn1 axes and knives of copper tempered to exceeding sharpness1 arrow-heads of agate1 even pieces of cloth1 are dug up in arid plains now without any trace of water for many leagues in or around them 7,russell1 ',the ,nitrate-,fields of ,chili1' p4 #bij74 ,,appendix ,,to ,,chapter ,,ix4 ,,nitrate ,,of ,,soda4 ,total ,shipments from ,south ,america1 #ahcj-ahib4 ,year4 ,tons4 ,year4 ,tons4 ,year4 ,tons4 #ahcj #hjj #ahgj #aca1djj #ahhf #dcg1ejj #ahce #f1bjj #ahge #cba1jjj #ahhg #fhj1fjj #ahdj #aj1ajj #ahhj #bag1cjj #ahhh #gde1gjj #ahde #af1hjj #ahha #cdd1fjj #ahhi #icj1jjj #ahej #bb1hjj #ahhb #dgg1hjj #ahij #a1jcj1jjj #ahee #da1hjj #ahhc #egb1djj #ahia #gij1jjj #ahfj #ee1bjj #ahhd #edj1ijj #ahib #gij1jjj #ahfe #aji1jjj #ahhe #dbc1ajj ,the following tables exhibit the total imports into ,europe1 and into the ,united ,kingdom from the years #ahgc-ib3-- ,,nitrate ,,of ,,soda1 #ahgc-ahib4 ,imports into ,europe4 ,imports into ,united ,kingdom4 ,year4 ,tons4 ,year4 ,tons4 #ahgc #bbe1jjj #ahgc #abd1jjj #ahgd #bcj1jjj #ahgd #ajh1bjj #ahge #bhj1jjj #ahge #afd1ijj #ahgf #cjj1jjj #ahgf #aff1hjj #ahgg #bjh1jjj #ahgg #fi1fjj #ahgh #bej1jjj #ahgh #ajd1djj #ahgi #bje1jjj #ahgi #ee1cjj #ahhj #adj1jjj #ahhj #dh1cjj #ahha #bcj1jjj #ahha #ed1hjj #ahhb #cce1jjj #ahhb #if1jjj #ahhc #ddj1jjj #ahhc #ajc1gjj #ahhd #eje1jjj #ahhd #ajc1gjj #ahhe #chj1jjj #ahhe #aji1djj #ahhf #ccj1jjj #ahhf #ge1ajj #ahhg #ddj1jjj #ahhg #hc1ajj #ahhh #fdj1jjj #ahhh #ajc1ajj #ahhi #gfj1jjj #ahhi #abj1jjj #ahij #ghd1jjj #ahij #aad1jjj #ahia #hea1jjj #ahia #aba1jjj #ahib #gie1jjj #ahib #aae1jjj ,,chapter ,x4 ,,sulphate ,,of ,,ammonia4 ,value of ,ammonia as a ,manure4 ,the value of ammonia salts as a manure has been long recognised2 indeed till recently ammonia was thought to be the most valuable form in which nitrogen could be applied as a plant-food--a view1 we may mention1 held by ,liebig4 ,while the plant1 no doubt1 can absorb its nitrogen in the form of ammonia1#bab as well as in other forms1 as we have already pointed out in previous chapters1 it is now fully recognised that ammonia salts1 when applied to the soil1 are converted into nitrates4 ,nitric acid1 then1 must be regarded as the most valuable1 inasmuch as it is the most rapidly assimilated form of nitrogen for the plant2 but next to nitric acid in value comes ammonia4 ,of the different forms of ammonia available for manurial purposes1 the only one used to a large extent is sulphate4 ,sources of ,sulphate of ,ammonia4 ,the oldest1 and what is still the chief source of this valuable salt1 is the gas-works1 where it is obtained as one of the bye-products in the manufacture of gas4 ,it is also obtained to a lesser extent from shale1 iron1 coke1 and carbonising works4 ,bones1 horn1 leather1 and certain other animal substances rich in nitrogen1 when subjected to dry distillation1 as is the case in certain manufactures1 such as the manufacture of bone-charcoal for use in sugar-refineries1 and the distillation of horn1 c41 in the manufacture of prussiate of potash1 also constitute less abundant sources4 ,ammonia from ,gas-works4 ,coal contains on an average from a half to one and a half per cent of nitrogen4 ,when it is subjected to dry distillation1 as is done in the gas-works1 the nitrogen which it contains is chiefly converted into ammonia1 and1 in the process of purification of the gas1 is removed in the gas-liquor1#bac which contains about one per cent of ammonia4 ,the ammonia recovered from this liquor by distillation is then absorbed in sulphuric acid4 ,it may be pointed out that nothing like all the nitrogen contained in the coal is recovered as sulphate of ammonia4 ,it has been calculated that only from a fifth to a tenth is actually recovered1 and many processes have been patented with a view to increasing the yield of ammonia in gas manufacture4 ,the total production of ammonia from gas-works may be placed at little over #ajj1jjj tons per annum for ,great ,britain4 ,mr ,l4 ,mond1 ,f4,r4,s41 recently drew attention to the possibility of largely increasing our supply of sulphate of ammonia from coal4 ,as indicating what an enormous source of sulphate of ammonia we have in coal1 ,mr ,mond calculated that its annual consumption in this country 7estimated at #aej1jjj1jjj tons7 would yield as much as #e1jjj1jjj tons of sulphate of ammonia4 ,other ,sources4 ,while the ammonia produced in the manufacture of gas has long been collected1 it is only of recent years that the other sources of ammonia have been developed4 ,next to the gas-works1 the shale-works of ,scotland form in this country the chief source of this valuable manure4 ,in these works the ammonia is obtained in distilling the paraffin shale by a method somewhat similar to that in use in the gas-works4 ,the amount of sulphate of ammonia obtained from this source is between #bj1jjj and #cj1jjj tons per annum4 ,recently the ammonia has been recovered from the blast-furnace gases in iron-works--some #fjjj tons being annually obtained in this way2 while from coke and carbonising works the annual production is about half that amount4 ,the combined annual production from all these sources may be put down at #adj1jjj tons1 the total production in ,europe being probably little more than #bjj1jjj tons4 ,in the ,appendix further statistics will be found4#bad ,composition1 c41 of ,sulphate of ,ammonia4 ,pure sulphate of ammonia is a whitish crystalline salt1 extremely soluble in water4 ,the commercial article1 however1 is generally greyish or brownish in colour1 owing to the presence of slight quantities of impurities4 ,the pure salt should contain #be4ge per cent of ammonia2 but the commercial article is generally sold on a basis of #bd4e per cent4 ,a useful test of its purity is the fact that when subjected to a red-heat it should almost entirely volatilise1 leaving very little residue4 ,the chief impurities which it is likely to contain are an excess of moisture1 free acid1 or the presence of insoluble matter4 ,certain samples contain small quantities of ammonium sulphocyanate1 an extremely poisonous substance for plants4 ,the presence of this dangerous impurity is easily detected by adding ferric chloride1 which1 in presence of the sulphocyanate1 produces a blood-red colour4 ,sulphate of ammonia is thus the most concentrated of all nitrogenous manures in common use1 and is for that reason the most expensive4 ,application4 ,for this reason1 as well as from the fact that it contains a speedily available form of nitrogen1 sulphate of ammonia should only as a rule be applied in comparatively small quantities--#ajj to #abe lb4 per acre4#bae ,it should also be applied before1 but not too long before1 the crop is likely to require it4 ,the reason of this is to give it time to be converted into nitrates4 ,the ability of the soil to retain ammonia has already been pointed out4 ,it is not safe1 however1 to rely too much on the retentive power of the soil for ammonia1 the conversion of ammonia into nitrates going on very quickly under favourable circumstances4 ,it is most profitably used as a manure for cereals1 and it has been found by ,lawes and ,gilbert in their experiments1 that an increase of one bushel of wheat and a corresponding increase of straw have been obtained for every #e lb4 of ammonia added to the soil4 ,as has been pointed out in the previous chapter1 the respective merits of sulphate of ammonia and nitrate of soda depend largely on the nature of the season during which they are used4 ,in wet seasons the sulphate is rather more favourable than the nitrate1 but1 on an average1 nitrate of soda is probably the more valuable manure--i4e41 due regard being had to the quantity of nitrogen the two manures respectively contain4 ,in one respect sulphate of ammonia is a much more useful manure than nitrate of soda1 as the nature of its action when applied to the soil permits of it being used as an ingredient of mixed manures4 ,like nitrate of soda1 but even to a greater extent1 its most favourable action is obtained when it is applied along with other manurial ingredients4 ,it should be applied at least a month earlier than nitrate4 ,it has been shown that in the case of chalky soils a certain loss of ammonia in sulphate of ammonia is apt to take place1 due to the action of the lime2 and this leads us to point out that1 in preparing mixed manures1 care ought to be taken that it is not mixed with any compound containing free lime or caustic alkali1 as otherwise loss of ammonia will ensue4 ,it should never1 for example1 be used along with basic slag4 ,,footnotes3 #bab ,from experiments by ,lehmann and others with buckwheat and maize1 it would seem that certain plants may prefer1 at certain stages of their growth1 ammonia to nitrates4 ,in the case of maize1 ammonia may be preferred in the early stages of growth1 while nitrates are preferred as it becomes more mature4 ,in view1 however1 of our present knowledge of nitrification1 it may well be doubted whether the conclusions arrived at from ,lehmann's experiments can be accepted4 #bac ,as the expense of converting the ammonia present in the ammoniacal liquor is considerable1 the practice of using the liquor itself as a manure has been advocated2 but as an objection to this it must be urged that1 besides being so bulky a manure1 the liquor contains various substances poisonous to plant-life4 #bad ,see ,appendix1 p4 #ceh4 #bae ,some crops1 however1 may with advantage be treated with larger quantities of sulphate of ammonia1 such as mangels and potatoes4 ,,appendix ,,to ,,chapter ,x4 ,,note 7p4 #cee74 ,the following table will exhibit the production of sulphate of ammonia in this country from #ahgj to #ahib3-- ,year4 ,tons4 ,year4 ,tons4 #ahgj #dj1jjj #ahhb #gb1jjj #ahga #da1jjj #ahhc #ge1jjj #ahgb #db1jjj #ahhd #hg1jjj #ahgc #dc1jjj #ahhe #ig1jjj #ahgd #de1jjj #ahhf #ajf1ejj #ahge #df1jjj #ahhg #aac1gjj #ahgf #dh1jjj #ahhh #abb1hjj #ahgg #eb1jjj #ahhi #acb1jjj #ahgh #ee1jjj #ahij #adj1jjj #ahgi #eg1jjj #ahia #adc1ejj #ahhj #fj1jjj #ahib #aeg1jjj #ahha #fe1jjj ,the following table exhibits the sources1 and the respective quantities from each source1 of the last seven years' production3-- #ahhf4 #ahhg4 #ahhh4 #ahhi4 #ahij4 #ahia4 #ahib4 ,gas-works #hb1ejj #he1jjj #ic1jjj #ajj1jjj #ajb1aej #ajg1iej #aab1jjj ,iron-works #d1jjj #e1jjj #e1cjj #f1jjj #e1jej #f1cjj #ab1jjj ,shale-works #ah1jjj #ba1jjj #bb1jjj #bc1jjj #bd1gej #bf1fjj #bh1jjj ,coke and carbonising works #b1jjj #b1gjj #b1ejj #c1jjj #b1cjj #b1hjj #e1jjj ,,chapter ,,xi4 ,,bones ,early ,use of ,bones4 ,a most important manure1 and one to the history of which very peculiar interest attaches1 is ,bones4 ,employed first in #aggd1 their use has steadily increased ever since1 and their popularity as a phosphatic manure is among farmers in this country quite unrivalled4 ,like guano1 although to a less extent1 the early practice of using bones has done much to arouse interest in the problems of manuring1 and to bring home to farmers the principles underlying that practice4 ,it was from bones that ,liebig first made superphosphate of lime1 and the distinguished veteran experimenter1 ,sir ,john ,bennet ,lawes1 has told us that the benefit accruing from the use of bones on the turnip crop first drew his attention to the interesting problem connected with the application of artificial manures4 ,bones were first used in ,yorkshire4 ,shortly afterwards they were applied to exhausted pastures in ,cheshire4 ,soon their use became so popular that the home supply was found inadequate2 and they were imported from ,germany and ,northern ,europe1 ,hull being the port of disembarkation4 ,so largely were they used by ,english farmers1 that ,baron ,liebig considered it necessary to raise a warning protest against their lavish application4 ,england is robbing all other countries of the condition of their fertility4 ,already1 in her eagerness for bones1 she has turned up the battle-fields of ,leipzig1 of ,waterloo1 and of the ,crimea2 already from the catacombs of ,sicily she has carried away the skeletons of many successive generations4 ,annually she removes from the shores of other countries to her own the manurial equivalent of three millions and a half of men1 whom she takes from us the means of supporting1 and squanders down her sewers to the sea4 ,like a vampire1 she hangs upon the neck of ,europe--nay1 of the entire world6--and sucks the heart-blood from nations without a thought of justice towards them1 without a shadow of lasting advantage to herself4#baf ,different ,forms in which ,bones are used4 ,it may be pointed out that bones have done much to alter our system of farming1 by helping to develop turnip culture4 ,used at first in comparatively large pieces1 experience gradually showed that a finer state of division facilitated their action4 ,yet it was long before the prejudice in favour of rough bones disappeared2 and it was not till #ahbi that ,mr ,anderson of ,dundee introduced machinery for preparing #a_/b-;inch and #a_/d-;inch bones and bone-dust4 ,in the early days of their use1 bones were fermented before being used1 in order to render their action more speedy when applied to the soil2 and this practice still obtains to the present day in some parts of the country among farmers4 ,this fermentation was often effected simply by mixing the bones with water1 and allowing the heap to lie for a week or two4 ,in other cases the bones were mixed with urine or other refuse matter4 ,the most important step1 however1 in the history of the treatment of bones for manure was the discovery in #ahdj1 by ,liebig1 of the action of sulphuric acid on them--a discovery which led to the institution of the manufacture of superphosphate of lime by ,sir ,john ,lawes4 ,the nature of this action will be explained in the following chapter1 so that we need only say here that the efficacy of the manure by treatment with sulphuric acid is more than doubled4 ,bones have thus been used1 and still are used1 in a variety of conditions1 such as in the raw or green state1 bruised1 boiled1 steamed1 fermented1 burned1 dissolved1 and broken or ground into various states of fineness1 to which the names of #a_/b-;inch1 #a_/d-;inch bones1 bone-meal1 bone-dust1 and floated bones are given4 ,we shall now proceed to discuss the composition of bones1 and investigate more exactly the nature of their action4 ,composition of ,bones4 ,the composition of bone-tissue varies considerably1 and depends on the age and kind of animal to which it belongs1 as well as to the part of the animal frame from which it is taken4 ,bones are made up of an organic and an inorganic part4 ,by steeping a piece of bone in a dilute acid solution1 the inorganic portion of the bone is dissolved out1 and the organic portion1 which forms the framework of the bone1 is alone left4 ,on the other hand1 by submitting a bone to the action of great heat1 the organic portion of the bone is driven off1 and all that remains is a quantity of ash4 ,the proportion of the organic to the inorganic matter varies considerably in different bones4 ,the bones of young animals contain more organic matter than those of old animals4 ,in compact bones1 also1 the organic matter is greater than in spongy bones4 ,the thigh-bone1 of all the bones1 contains most inorganic matter4 ,in short1 bones which have to bear the greatest strain are richest in inorganic matter4 ,of the bones of animals1 fish-bones exhibit the greatest variety of composition1 some being almost entirely made up of organic matter1 while others are similar in their composition to the bones of quadrupeds4 ,the ,organic ,matter of ,bones4 ,the organic portion of bones is almost entirely made up of a substance to which the name ossein has been given1 and which1 when boiled for a long time1 is converted into gelatine4 ,this ossein1 which forms on an average from #be to #cj per cent of the weight of bones1 is extremely rich in nitrogen1 containing over #ah per cent4 ,inorganic ,portion of ,bones4 ,the inorganic portion1 which forms about #gj per cent1 is made up chiefly of phosphate of lime4 ,the dry leg-bones of oxen and sheep1 according to ,heintz1 have the following percentage composition3-- ,per cent4 ,phosphate of lime #eh to #fc ,carbonate of lime #f to #g ,phosphate of magnesia #a to #b ,fluoride of calcium #b ,organic matter #be to #cj ,according to ,payen and ,boussingault1 raw bones contain #f-a_/d per cent of nitrogen and #h per cent of water4 ,pure bones are thus seen to contain about #bi per cent of phosphoric acid and #f-a_/d per cent of nitrogen4 ,the composition of the commercial article1 however1 differs very widely4 ,this is due to the fact that bones collected from ,india and ,america1 where they have been long exposed to atmospheric influences1 have lost much of their organic matter4 ,the amount of sand and earthy impurities also varies very considerably4 ,treatment of ,bones4 ,bones are used for the manufacture of glue and gelatine4 ,these are extracted from them by steaming the bones4 ,the bones after treatment are used as a manure4 ,the improvement noted in the action of the bones thus treated led to the introduction of the use of steamed bones as a manure4 ,raw bones are now rarely used4 ,the fat present in raw bones retards their decomposition in the soil4 ,probably1 as has been suggested1 it forms along with lime an insoluble soap which prevents the mineral matter in the bone being dissolved by the carbonic acid of the soil4 ,in the process of boiling or steaming a certain loss of nitrogen takes place1 greater or less1 according to the length of time they are boiled or steamed1 and in the latter case the pressure applied4 ,a more economical method for extracting the fat has been introduced by using benzine1 but this process is not used to any extent4 ,the loss of nitrogen in the former case is more than compensated for by their more speedy action as a manure when applied to the soil4 ,bone-meal of good quality contains from #de to #eebag per cent of phosphate of lime1 and #c-a_/b per cent of nitrogen4 ,our present total consumption of bones is probably little less than #ajj1jjj tons per annum1 of which about half is obtained from home collections1 over #bj1jjj tons being annually collected in and around ,london alone4 ,action of ,bones4 ,it is well known that bones are a slow-acting manure4 ,they may be said to possess both a mechanical and chemical action when applied to the soil4 ,when they putrefy1 their nitrogen is slowly converted into ammonia1 and carbonic acid as well as various organic acids are formed1 which1 acting upon the insoluble mineral matter in the bones1 renders it available for plant uses4 ,bones thus1 when applied in large quantities1 may not merely act directly as suppliers of plant-food1 but in the course of their putrefaction may act upon a certain amount of the inert fertilising matter of the soil and render it available4 ,the more readily1 then1 bones putrefy1 the more speedy will be their effect4 ,as we have already pointed out1 bones1 in order to increase their efficiency1 are often fermented before application4 ,the removal of the fat is another means of increasing the rate of their action1 but the fineness to which they are ground determines this more than anything else4 ,much ingenuity has been expended in perfecting machinery for grinding bones4 ,at one time in ,germany they were pounded in stamps similar to those used for ore4 ,in ,america what has been called floated bone has been prepared4 ,this bone is so fine that it actually floats in the air like flour-dust1 and is made by whirling the bones against one another4 ,the action of bones prepared in this way is of course very speedy1 but the difficulty of applying a manure in such a fine state of division to the soil is great4 ,the expense of the process also is considerable4 ,the ease with which bones when ground into a fine state of division putrefy1 is evidenced by the fact that bone-flour has to be salted in order to enable it to keep4 ,another condition which determines the rate at which the fertilising matters in bones become available is the nature of the soil4 ,fermentation1 as we have already seen1 requires a plentiful supply of air1 and a certain amount1 but not too much1 of moisture4 ,consequently bones act best in medium soils--soils which are neither too light and dry1 nor too close and wet4 ,there can be no doubt that what gives to bones a peculiar value in the eyes of the farmer is the fact that they form a manure of a lasting character4 ,they give what has been termed backbone to a soil4 ,but the tendency of modern agricultural practice is to use quick-acting manures rather than slow4 ,this has been admirably put by ,professor ,storer in the following words3 ,the old notion1 that those manures are best which make themselves felt through a long series of years1 is now recognised to be an error4 ,the adage1 that 'one cannot eat the cake and have the cake' is conspicuously true in agriculture2 and just as it is the part of prudence in household or maritime economy to abstain from laying in at any one time more provisions than can be properly disposed of in a year or during a voyage1 so should the farmer refrain from bringing to the land an unnecessary excess of plant-food4 ,such food is liable to spoil withal in the soil1 as well as other kinds of provisions that are kept too long in store4 ,a just proportion of food1 properly prepared1 is the point to be aimed at always4 ,in view1 therefore1 of what has just been said1 it might seem best to use bones in the form in which they are most speedily available--viz41 as dissolved bones4 ,this would be so if bones were the only source we possessed for the manufacture of superphosphate of lime2 but we now have1 in the various mineral phosphates1 abundant and cheaper sources of this valuable manure4 ,the opinion of leading agriculturists and agricultural chemists is rather in favour of applying bones in the undissolved condition4 ,for one thing1 it seems far from economical to utilise an expensive material such as bones for manufacturing an article which can be equally well manufactured from cheaper materials2 for once the phosphate of lime is dissolved1 it is equally valuable from whatever source it may be derived4 ,of course this is not tantamount to saying that dissolved bones as a manure are no more valuable than superphosphate4 ,in dissolved bones we have1 in addition to soluble phosphate1 a considerable proportion of undissolved bone-tissue1 containing a certain quantity of nitrogen and organic matter2 but so far as the soluble phosphate is concerned1 it seems only rational to conclude that its efficacy is equally great1 whether it be derived from bone or mineral phosphate4 ,another reason is1 that much of the characteristic action of bones is lost by treating them with sulphuric acid4 ,as ,dr ,aitken has pointed out1 the germ life in the soil and in the bones gradually converts them into a form available for the nourishment of plants2 but to dissolve bones with sulphuric acid is to kill out the germ life and retard the decay of any nucleus of bone in the dissolved manure4 ,dissolved ,bones4 ,dissolved bones1 however1 are still manufactured4 ,formerly the manure called dissolved bones was often a mixture of mineral superphosphate along with undissolved bone-meal1 but recent legislation has stopped the continuance of this practice4 ,the composition of dissolved bones varies somewhat1 the percentage of soluble phosphate being about #bj to #bc per cent1 the insoluble amounting to from #i to #aj per cent1 and the nitrogen from #b-a_/b to #c-a_/b per cent4#bah ,another reason against dissolving bones is to be found in the difficulty experienced in dissolving their phosphate4 ,bones1 especially when raw1 are not easily acted upon by acids4 ,crops suited for ,bones4 ,bones are commonly regarded as being specially beneficial to pasture-land1 to which they are applied as a top-dressing4 ,turnips1 tobacco1 potatoes1 vines1 and hops are also much benefited by the application of bones4 ,in ,america1 mixed with wood-ashes 7the chief manurial constituent of which is potash71 they have been extensively used as a substitute for farmyard manure1 and have been applied at the rate of #e to #f cwt4 per acre4 ,in ,saxony1 according to ,professor ,storer1 #a cwt4 of fine bone-meal is worth as much as #be to #cj cwt4 of farmyard manure4 ,bone-ash4 ,the ash which is left on burning bones used to be an article of considerable manurial importance4 ,it is still imported from ,south ,america in some quantity1 and is used chiefly in the pottery industry4 ,it is occasionally still used to a limited extent for the manufacture of high-class superphosphates4 ,it is extremely rich in phosphate of lime1 of which it contains between #gj and #hj per cent2 but of course it is devoid of nitrogen4#bai ,bone-ash is best used in the dissolved form1 as it possesses no characteristic action such as is possessed by bones4 ,bone-char or ,bone-black4 ,when heated in a closed retort1 bones are not converted into bone-ash1 but into a body called bone-char4 ,this body is similar in composition to bone-ash1 except for a certain percentage of charcoal--amounting1 on an average1 to #aj per cent4 ,it contains but little nitrogen and other organic matter4 ,bone-black or bone-char is an article which is prepared in enormous quantities for use in sugar-refineries1 where it is used in the purification of sugar4 ,after use it may be renovated by submitting it to heat2 but as this process gradually lessens the percentage of carbon it contains1 after a certain period it becomes too poor in this substance for efficiently acting as a filter4 ,when this takes place it is technically known as spent char1 and is used for the manufacture of superphosphates4 ,spent char is a highly phosphatic substance1 being very little poorer than bone-ash1 and containing about #gj per cent of phosphate of lime4#bbj ,,footnotes3 #baf ,it is only fair to ,liebig to say that when he wrote these words the practically boundless supply of mineral phosphates which we now know to exist in many parts of the world was little dreamt of4 #bag ,see ,appendix1 ,note ,i41 p4 #cga4 #bah ,see ,appendix1 ,note ,,ii41 p4 #cga4 #bai ,see ,appendix1 ,note ,,iii41 p4 #cgb4 #bbj ,see ,appendix1 ,note ,,iv41 p4 #cgb4 ,,appendix ,,to ,,chapter ,,xi4 ,,note ,i4 7p4 #cfd74 ,the following analysis will serve to show the composition of bone-meal3-- ,moisture #aj4dc 99,organic matter #cb4cj ,phosphate of lime #dh4dj ,carbonate of lime1 magnesia1 c4 #g4bj ,insoluble siliceous matter #a4fg ------ #ajj4jj ------ 99,containing3-- ,nitrogen #c4ga ,equal to ammonia #d4ea ,,note ,,ii4 7p4 #cfh74 ,,composition ,,of ,,dissolved ,,bones4 ,the accompanying analysis may be taken as representing the average composition of dissolved bones3-- ,moisture #aj4aj 99,organic matter and water of combination #bi4cd ,monobasic phosphate of lime #aa4bc 7,equal to tricalcic phosphate rendered soluble #ag4eh7 ,phosphate soluble in ammonium citrate #ad4jb ,insoluble phosphate of lime #a4hh ,calcium sulphate1 magnesia1 alkalies1 c4 #cj4bc ,sand #c4bj ------ #ajj4jj ------ 99,containing3-- ,nitrogen #b4fb ,equal to ammonia #c4ah ,,composition ,,of ,,compound ,,bones4 ,the following analysis illustrates the composition of compound bones3-- ,moisture #h4aj 99,organic matter and water of combination #cg4bb ,monobasic phosphate of lime #ac4fh 7,equal to tricalcic phosphate rendered soluble #ba4db7 ,insoluble phosphate of lime #aj4dh ,calcium sulphate1 magnesia1 alkalies1 c4 #bf4jb ,sand #d4ej ------ #ajj4jj ------ 99,containing3-- ,nitrogen #a4ij ,equal to ammonia #b4cj ,,note ,,iii4 7p4 #cfi74 ,as showing the composition of bone-ash1 the following analysis may be quoted3-- ,moisture 4#be ,organic matter 4#he 99,phosphoric acid #ce4ef ,lime #dg4ji ,magnesia1 alkalies1 c4 #i4hj ,sand #f4de ------ #ajj4jj ------ 99,equal to tricalcic phosphate #gg4fc ,,note ,,iv4 7p4 #cgj74 ,composition of bone-char 7on dry sample73-- ,carbon #aj4ea ,calcium and magnesium phosphates1 calcium fluoride1 c4 #hj4ba ,calcium carbonate #h4cj ,calcium sulphate 4#ag ,ferric oxide 4#ab ,silica 4#cd ,alkaline salts 4#ce ------ #ajj4jj ------ ,,chapter ,,xii4 ,,mineral ,,phosphates4 ,in this chapter we shall give an account of the more commonly occurring mineral phosphates4 ,in ,chapter ,v41 where we discussed the position of phosphoric acid in agriculture1 it was pointed out that mineral phosphates were very abundant1 and that large deposits of them were found in many parts of the world4 ,coprolites4 ,reference may first be made to the so-called coprolites or phosphatic nodules which have been found in great abundance in the greensand formation1 in the crag of the eastern counties1 and in the chalk formation of the southern counties4 ,these coprolites are rounded nodules1 and are composed of the fossil excrements and remains of ancient animals4 ,they are found in large quantities in ,cambridgeshire1 and were discovered by ,dr ,buckland many years ago4 ,the history of their discovery is not a little curious4 ,the manurial properties of road-scrapings in parts of ,cambridgeshire were noticed1 and on being examined were found to be in part composed of phosphate of lime1 derived from phosphatic nodules dug out of the underlying greensand1 and used for the purpose of repairing roads4 ,professor ,henslow first drew attention to them at a meeting of the ,british ,association held in ,cambridge in #ahde1 and pointed out that they contained about #fj per cent of phosphate of lime4 ,they were also found in enormous quantities in ,suffolk1 ,norfolk1 ,bedfordshire1 and ,essex1 and were for a long time largely used in the manufacture of superphosphate1 but of late years have not been used to anything like the same extent1 owing to the fact that there are richer and cheaper sources of phosphate of lime available4 ,in #ahhg about #bj1jjj tons of coprolites were raised4 ,the richest were those obtained in ,cambridge1 while those got from ,bedfordshire were about the poorest4 ,deposits have also been found in ,france and other countries4 ,the average amount of phosphate of lime in ,english coprolites is between #ej and #fj per cent1 while the ,french contain about #de per cent4 ,canadian ,apatite or ,phosphorite4 ,we have already referred in ,chapter ,v4 to large deposits of apatite or phosphorite found in ,canada4 ,the ,canadian mines commenced to be worked about fifteen years ago1 and the output now amounts to nearly #be1jjj tons per annum4#bba ,a portion of this goes to the ,united ,states2 the rest1 amounting to about #bj1jjj tons1 being shipped to ,england1 whence it is again exported to ,hamburg and other places4#bbb ,it contains from #gj to #hj per cent of phosphate4 ,deposits are also found at ,estremadura in ,spain1 and in ,norway4 ,estremadura or ,spanish ,phosphates4 ,large deposits of phosphate have long been known to exist at ,estremadura in ,spain1 and the mines at ,caceres have been worked on a large scale for seventeen years1 and about half a million tons have been raised4 ,in #ahhb the imports into this country amounted to over #ef1jjj tons2 but latterly they have only been about a fourth of this amount4 ,dr ,dauberry visited the deposits in #ahdc1 and wrote a most interesting account of them4 ,they do not seem1 however1 to have been imported for purposes of superphosphate manufacture till a number of years afterwards4 ,of ,estremadura phosphate there are three classes1 containing respectively #ej1 #fj1 and #gj per cent of phosphate of lime1 the lowest quality being the commonest4#bbc ,norwegian ,apatite4 ,this apatite has ceased to be imported of late years1 owing to a duty on exportation4 ,charleston or ,south ,carolina ,phosphate4 ,for a number of years these deposits have formed the chief source of phosphate of lime used in the manufacture of mineral superphosphates in this country 7in fact they have furnished two-thirds of our phosphate supply during recent years74 ,discovered twenty-five years ago1 some four to five million tons have already been shipped4 ,about half a million tons were raised in #ahhf from these mines1 which are the most abundant in the world4 ,there are two kinds--the so-called land and river phosphates4 ,the former contains more oxide of iron and alumina1 and is therefore less pure than the latter1 in which the iron and alumina do not exceed #b per cent4 ,the river phosphate is dredged from the ,bull1 ,coosaw1 and ,beaufort rivers4 ,of phosphate of lime it contains from #ej to #fj per cent4 ,it is generally sold in three grades--#ej to #eb per cent1 #ee to #ef per cent1 and #eh to #fj per cent of phosphate of lime4 ,it will thus be seen to be incapable of producing very high-class superphosphates --i4e41 containing more than #cj per cent soluble phosphate4 ,this point will be more intelligible when we describe the manufacture of superphosphate4 ,the demand for these phosphates in the ,united ,states has increased enormously in recent years1 owing to the increase in the quantity of manure used4 ,belgian ,phosphate4 ,another very important source of mineral phosphates are deposits discovered some years ago in ,belgium near ,mons4 ,these phosphates are of different qualities1 and are found1 some in layers near the surface in pockets forming the richest class1 and containing from #de to #fe per cent of phosphate1 and some in the form of a friable phosphatic rock1 the so-called craie-grise 7phosphatic chalk71 containing from #be to #ce per cent of phosphate of lime4 ,the higher quality of ,belgian phosphate is pretty well exhausted1 and it is the second class that forms the bulk of the ordinary ,belgian phosphate at present exported4 ,the commercial article contains about #ce to #dj per cent of phosphate1 and about #de per cent of carbonate of lime4 ,the fact of its poor quality1 together with the large percentage of carbonate of lime it contains1 renders its adoption alone in the manufacture of superphosphate unsuitable4 ,attempts have been made to get rid of a portion of this carbonate of lime and to raise the percentage of phosphate4 ,for this purpose the phosphate has been calcined1 but this was soon found to be a great mistake4 ,other means have been adopted1 with the result that the percentage has been increased to #ej per cent4 ,it is consequently used in small quantities as a drier1 for which it is peculiarly suited on account of its carbonaceous nature1 along with the higher-class phosphates4 ,in the year #ahhf about #ade1jjj tons of this phosphate were raised1 of which about #de1jjj tons were imported into the ,united ,kingdom4 ,somme ,phosphate4 ,still more recently a discovery of phosphate deposits has been made in the ,somme and ,pas de ,calais departments in the north of ,france1 adjoining1 and similar in character to1 the ,belgian deposits4 ,the only difference between ,belgian and ,french phosphates is1 that the latter is of a higher quality1 and contains from #ej to #hj per cent of phosphate of lime4 ,a very large demand for these phosphates sprang up1 and in #ahhh1 although they had only been worked for some two years1 no less than #aej1jjj tons had been raised1 of which about one-half contained from #gj to upwards of #ge per cent4 ,there are four grades in the market1 containing #ee to #fj1 #fj to #fe1 #gj to #ge1 and #ge to #hj per cent of phosphate of lime4 ,the highest quality furnishes the chief material for the manufacture of high-grade superphosphates4 ,florida ,phosphate4#bbd ,during the last few years large quantities of phosphates have been imported from ,florida4 ,these are of different qualities1 the land rocks now imported containing from #gj to #hj per cent of phosphate of lime1 and the river phosphate about #fj per cent4 ,the latter class are similar in composition to the best ,south ,carolina river-phosphates1 which they much resemble4 ,lahn ,phosphate4 ,phosphate deposits were found at ,nassau in ,germany in #ahfd2 but as the phosphate contained a considerable proportion of iron and alumina1 they are not used in this country now1 although they are in ,germany for double superphosphate manufacture4 ,bordeaux or ,french ,phosphate4 ,similar in quality to ,lahn phosphate is that obtained in the neighbourhood of ,bordeaux4 ,algerian ,phosphate4 ,excellent phosphates are now being sent from ,algeria--some cargoes being as rich as #gj per cent4 ,crust ,guanos4 ,we have already referred to the guanos in the chapter on ,guano4 ,they are also known under the name of ,caribbean phosphates1 and come from the ,west ,india ,islands4 ,the chief kinds are ,aruba1 ,curacao1 ,sombrero1 and ,navassa1 the ,great ,cayman1 ,redonda1 and ,alta ,vela4 ,most of them are of high quality1 containing from #fj to #hj per cent of phosphate1 and are thus suited for the manufacture of high-class superphosphates4 ,some of them1 however1 contain a considerable proportion of iron and alumina1 and are not suitable for this purpose4 ,the ,redonda and ,alta ,vela phosphates consist chiefly of phosphate of alumina4 ,value of ,mineral ,phosphates as a ,manure4 ,while it is commonly regarded as unadvisable to use mineral phosphates directly as phosphatic manures1 it may well be questioned how far such an opinion is warranted by actual experience4 ,professor ,jamieson of ,aberdeen1 in his interesting and valuable experiments1 has drawn attention to the fact that coprolites in a fine state of division are an extremely valuable source of phosphoric acid for crops1 and are a more quickly available source than is commonly supposed4 ,experiments conducted elsewhere with ground coprolites and other mineral phosphates corroborate ,professor ,jamieson's conclusions4 ,the successful use of ,thomas-phosphate has drawn attention to the possibility of profitably applying undissolved mineral phosphate to the soil2 and no doubt the practice may in future years be increased4 ,at present1 however1 with the exception of ,thomas-phosphate1 mineral phosphates alone are used for conversion into superphosphate4 ,,footnotes3 #bba ,since the discovery of the ,florida deposits of phosphate1 the working of the ,canadian mines has been practically abandoned4 #bbb ,see ,appendix1 p4 #cha4 #bbc ,these phosphates are now no longer worked4 #bbd ,these deposits were discovered a few years ago2 and as they are of considerable extent and high quality1 have entirely revolutionised the phosphate market4 ,about #cjj1jjj tons are now annually raised in ,florida4 ,,appendix ,,to ,,chapter ,,xii4 ,,note 7p4 #cge74 ,,the ,,following ,,table ,,shows ,,the ,,imports ,,of ,,phosphates ,,into ,,the ,,united ,,kingdom1 ,,and ,,the ,,countries ,,of ,,production1 ,,during ,,the ,,years #ahhe-ib4 ---------------------------------------- ---------------------------- #ahhe4 #ahhf4 #ahhg4 #ahhh4 #ahhi4 ---------------------------------------- ---------------------------- ,tons4 ,tons4 ,tons4 ,tons4 ,tons4 ,united ,states #ach1hdd #add1fbc #afe1bge #aaa1cfi #abb1eed ,canada #ba1dhd #ah1jfi #ai1aid #ab1dbc #bc1big ,dutch ,west ,indies 7,curacao1 ,aruba7 #aa1ehh #ab1eha #i1eje #aj1gcf #ad1gcj ,british ,west ,indies 7,sombrero1 c47 #g1gbg #c1cea #f1dea #aa1jaj #a1hhj ,spain and ,portugal #ai1bhb #e1hbe #ae1fab #f1igh #a1cbf ,belgium #ce1dje #ca1eea #de1cbb #ed1bfa #fd1fdc ,holland #hfe #b1aid #d1ggh #d1acg #b1bgj ,france #b1bgf #a1ejc #aa1adj #ci1jei #fe1dij ,australia - #bjj #cej - #a1bej ,germany #gjd - - - - ,hayti 7,san ,domingo7 - #b1age #c1jdd #f1bch #d1jid ,brazil - - #a1bjj - - ,venezuela and ,guiana - - #dje - - ,norway - - - - - ,other countries #cig #a1jci #a1aci #a1fge #cij 99,florida phosphate4 - - - - - ,carolina phosphate4 - - - - - ---------------------------------------- ---------------------------- ---------------------------------------- ------------ #ahij4 #ahia4 #ahib4 ---------------------------------------- ------------ ,tons4 ,tons4 ,tons4 ,united ,states #agg1bhc 99#aca1jhd 99#bja1dfe ,canada #ba1jhi #ae1iah #g1had ,dutch ,west ,indies 7,curacao1 ,aruba7 #ad1gfc #h1hea #f1fdh ,british ,west ,indies 7,sombrero1 c47 #c1igj #a1ifj #b1dgc ,spain and ,portugal - #cbj #iga ,belgium #hb1jif #gj1gbc #fe1jgi ,holland #b1dbh #c1dcd #f1fbg ,france #ce1fei #ah1cbe #ah1bci ,australia - - - ,germany - - - ,hayti 7,san ,domingo7 #iib #a1fci #b1ife ,brazil - - - ,venezuela and ,guiana - #edj - ,norway #d1aea #a1die #cje ,other countries #a1jgj #a1dhc #a1eid 99,florida phosphate4 - #ce1bjc #ff1cbg ,carolina phosphate4 - #if1hha #ace1ach ---------------------------------------- ------------ ,,chapter ,,xiii4 ,,superphosphates4 ,as was mentioned in the chapter on ,bones1 ,liebig in the year #ahdj discovered that the effect of adding oil of vitriol1 or sulphuric acid1 to bones was to render the phosphate they contain soluble4 ,this discovery marked an epoch in the history of artificial manures1 and laid the foundation of the now enormous manufacture of superphosphate4 ,in #ahfb the juries of the ,london ,international ,exhibition published an elaborate report containing an interesting article on the manure trade of ,great ,britain1 in which it was stated that the annual quantity of superphosphate then made amounted to from #aej1jjj to #bjj1jjj tons4 ,now it may be placed not far short of a million tons4 ,probably that made in the ,united ,states is considerably more4 ,in the first instance1 superphosphate was manufactured by ,sir ,john ,lawes from spent bone-char4 ,this was superseded by coprolites and ,estremadura phosphorite1 ,suffolk coprolites being for many years the chief material employed4 ,this in turn was succeeded by the richer ,cambridge coprolites1 but of late years coprolites have practically ceased to be a source of superphosphate1 the other mineral phosphates mentioned in the previous chapter--such as the ,south ,carolina1 ,belgian1 ,somme1 c41 phosphates--taking their place4 ,manufacture of ,superphosphate4 ,the manufacture of superphosphate is of too technical a nature to permit of discussion in a work of this kind4 ,it is important1 however1 that the general principles underlying the process of manufacture and the chemical changes in the phosphate taking place during the process be clearly understood4 ,in the first place1 great importance attaches in the manufacture of the superphosphate to the fineness of division of the raw material1 and much ingenuity has been spent on apparatus designed for this purpose4 ,the difficulty of grinding the phosphate varies1 of course1 with the nature of the material used--apatite1 for example1 being much more difficult to reduce to the necessary fineness than phosphatic guano4 ,the finer the state of division1 the more complete will be the decomposition of the phosphate by the acid4 ,mr ,warington recommends that for first-class work the powder should be so fine as to admit of it passing through a sieve of eighty wires to the inch4 ,after the phosphate is reduced to powder1 it is mixed with acid4 ,this takes place in the mixer1 which is generally in the form of an iron cylinder furnished in the centre with a revolving shaft1 the sulphuric acid used being the ordinary chamber acid 7sp4 gr4 #a4eg74 ,whatever strength of acid is used1 there must be a certain quantity of water present to form gypsum4 ,it is to the formation of gypsum in the resulting product that the dryness of the superphosphate is due4 ,the proportion of sulphuric acid used depends on the composition of the phosphate2 and here it may be pointed out that the presence of much carbonate of lime is a most important factor in determining the quantity of acid required4 ,the reason of this is1 that where carbonate and phosphate of lime are present together1 sulphuric acid first acts upon the carbonate1 and it is not till this is wholly decomposed that the phosphate can be acted upon4 ,hence mineral phosphates with a large percentage of carbonate of lime do not constitute such an economical material for the manufacture of superphosphate as those in which the percentage of carbonate is small4#bbe ,a certain amount of heat is necessary for the purpose of enabling a quick decomposition to take place4 ,for this purpose the sulphuric acid added has been previously heated4 ,in the ordinary manufacture of superphosphate1 however1 this is not considered necessary1 as the heat developed by the chemical action between the phosphate and the acid is sufficiently great4 ,the phosphate1 after being thoroughly mixed with the acid1 is discharged into what is technically known as the pit1 a chamber built of brick or concrete4 ,the mixture1 which is in a fluid state when it enters the pit1 very soon hardens1 and is dug out in a day or two4 ,it is next reduced to powder in a disintegrator1 and is then ready for use as a manure4 ,nature of the ,reaction taking place4 ,in order to clearly understand the nature of the reaction which takes place when sulphuric acid is added to a phosphatic material1 it may be well to say a word or two on the composition of the different compounds of lime and phosphoric acid4 ,phosphates of ,lime4 ,in the various phosphatic manures used in agriculture there are four different kinds of phosphates4 ,in the commonest form1 popularly called bone-phosphate1 which is the form in which lime and phosphoric acid are combined in bones1 guano1 and the ordinary mineral phosphates1 the lime and phosphoric acid are combined in the form of what is known as tribasic phosphate of lime1 or tricalcic phosphate--that is to say1 for every equivalent of phosphoric acid there are three equivalents of lime4 ,this may be represented as follows3-- ,lime ,lime ,phosphoric acid4 ,lime ,or we may also say that for every #adb parts by weight of phosphoric acid there are #afh parts by weight of lime in this form of phosphate4 ,this is the least soluble form of phosphoric acid1#bbf and is the form generally referred to in commercial analyses as insoluble phosphate4 ,when this phosphate is acted upon with sulphuric acid1 a soluble phosphate is formed1 as ,liebig first showed1 to which the name superphosphate has been given1 and which is also known as monobasic phosphate of lime1 or monocalcic phosphate4 ,this compound may be represented as containing1 instead of three equivalents of lime1 only one1 the other two equivalents being replaced by water4 ,this compound may be represented as follows3-- ,lime ,water ,phosphoric acid4 ,water ,in it1 for every #adb parts of phosphoric acid1 there are only #ef parts of lime4 ,it is soluble in water1 and gives to the commercial article known as superphosphate of lime its value4 ,intermediate in composition between these two phosphates there is another known as precipitated phosphate of lime1 or dicalcic phosphate 7the same as reverted phosphate71 which contains two equivalents of lime and one equivalent of water as follows3-- ,lime ,lime ,phosphoric acid4 ,water ,this compound contains1 for every #adb parts of phosphoric acid1 #aab parts of lime2 and in solubility occupies an intermediate position4 ,lastly1 there is a fourth compound of lime and phosphoric acid1 which only occurs in one phosphatic manure--viz41 phosphatic slag1 in which indeed it was first discovered--which consists of four equivalents of lime to one of phosphoric acid1 to which the name tetrabasic phosphate of lime or tetracalcic phosphate has been given4 ,its composition may be illustrated as follows3-- ,lime ,lime ,phosphoric acid4 ,lime ,lime ,or1 for every #adb parts of phosphoric acid1 there are #bbd parts of lime4 ,contrary to what we might expect1 this phosphate is less insoluble than the ordinary tribasic or bone phosphate4 ,this may be owing to the fact that1 in the tetrabasic phosphate1 there is more lime present than that which the phosphoric acid can retain with strong chemical affinity4#bbg ,in the manufacture of superphosphate the tribasic phosphate is converted into the soluble phosphate--the lime1 which was formerly in combination with the phosphoric acid1 uniting with the sulphuric acid1 and forming gypsum4#bbh ,it was till recently supposed that soluble phosphate and gypsum were the only two resulting products of this decomposition4 ,it has been recently shown1 however1 by ,ruffle and others1 that this is not1 strictly speaking1 the case1 and that probably a large proportion of free phosphoric acid is formed2 in fact1 it seems probable that in the first stage of the reaction1 only phosphoric acid is produced1 and that this subsequently acts upon the undecomposed phosphate1 with the production of monocalcic phosphate4#bbi ,the amount of sulphuric acid which experience has shown it is necessary to add for the successful and economical manufacture of superphosphate1 depends on the composition of the raw material employed4 ,the larger the percentage of tribasic phosphate1 the larger the quantity of sulphuric acid required for its decomposition2 but sometimes even a poor phosphate consumes a large amount of sulphuric acid4 ,this is the case where much calcium carbonate or fluoride is present in the raw phosphate1 as both of these compounds require a quantity of acid for their decomposition1 which takes place before the decomposition of the phosphate4 ,hence phosphates rich in carbonate of lime are not well suited as economical materials from which to manufacture superphosphate4 ,reverted ,phosphates4 ,a change which is apt to take place in superphosphate after its manufacture is what is known as reversion of the soluble phosphate4 ,thus it is found that on keeping superphosphate for a long time the percentage of soluble phosphate becomes less than it was at first4 ,the rate at which this deterioration of the superphosphate goes on varies in different samples4 ,in a well-made article it is practically inappreciable1 whereas in some superphosphates1 made from unsuitable materials1 it may amount to a considerable percentage4 ,the causes of this reversion are twofold4 ,for one thing1 the presence of undecomposed phosphate of lime may cause it4 ,this source of reversion1 however1 is very much less important than the other1 which is the presence of iron and alumina in the raw material4 ,when a soluble phosphate reverts1 what takes place is the conversion of the monocalcic phosphate into the dicalcic4 ,now in the first case1 where reversion is due to the presence of undecomposed phosphate1 the action taking place may be represented as follows3-- ,lime lime ,lime phosphoric acid water phosphoric acid ,lime water 7,one molecule of insoluble 7,one molecule of soluble phosphate7 phosphate7 ,lime lime ,lime phosphoric acid lime phosphoric acid4 ,water water 7,one molecule of reverted 7,one molecule of reverted phosphate7 phosphate47 ,it may be mentioned1 however1 that reversion from this cause probably takes place to a very slight extent in practice4#bcj ,where reversion is due to the presence of iron and alumina in the raw material1 the nature of the reaction is not well understood1 and is consequently not so easily demonstrated as in the former case4 ,where iron is present in the form of pyrites1 or ferrous silicate1 it does not seem to cause reversion4 ,it is only when it is present in the form of oxide--and in most raw phosphatic materials it is generally in this latter form#bca--that it causes reversion in the phosphate4 ,value of reverted ,phosphate4 ,the value of reverted phosphate is a subject which has given rise to much dispute among chemists4 ,that it has a higher value than the ordinary insoluble phosphate is now admitted2 but in this country1 in the manure trade1 this is not as yet recognised4 ,at first it was thought that it was impossible to estimate its quantity by chemical analysis4 ,this difficulty1 however1 has been overcome1 and it is generally admitted that the ammonium citrate process furnishes an accurate means of determining its amount4 ,both on the ,continent and in the ,united ,states reverted phosphate is recognised as possessing a monetary value in excess of that possessed by the ordinary insoluble phosphate4 ,the result is1 that raw phosphates containing iron and alumina to any appreciable extent are not used in this country1 although they do find a limited application in ,america and on the ,continent4 ,composition of ,superphosphates4 ,superphosphates as manufactured may be divided1 generally speaking1 into three classes--viz41 low class1 medium1 and high class4 ,the ordinary or medium class contains from #be to #bg per cent of soluble phosphate2 and here it may be pointed out that by soluble phosphate is meant the percentage of tribasic phosphate which has been dissolved--not1 as might at first sight be supposed1 the percentage of monocalcic phosphate4 ,the lower-class superphosphates are those containing less than #be per cent1 generally #bc to #be per cent1 of soluble phosphate2 while the high-class superphosphate may contain from #cj to #de per cent4 ,for the manufacture of high-class superphosphate only a certain number of raw phosphates are available1 such as ,curacao and ,somme phosphates1 phosphatic guanos1 bone-char1 c4 ,certain processes have been patented for the manufacture of even more concentrated superphosphates1 and by them phosphates containing as much as #dj per cent of soluble phosphoric acid--i4e41 equal to #hg per cent of soluble phosphate--have been prepared4 ,to this class belongs the so-called double superphosphate1 manufactured at ,wetzlar in ,germany4 ,such a concentrated form of manure is naturally very expensive to manufacture1 and is hardly to be recommended for home consumption4 ,where1 however1 manures have to be conveyed long distances1 and the freight is consequently very high1 such a concentrated article may be found most economical4 ,action of ,superphosphates4 ,when superphosphate is applied to the soil it is converted into an insoluble state4 ,in short1 the process of reversion is carried on on a wholesale scale4 ,this is due to the lime1 iron1 and alumina salts which the soil contains4 ,in all probability the phosphate is finally converted into a hydrated ferric or aluminic phosphate1 in which form it is gradually acted upon by the sap of the plant-roots as required4 ,this being the case1 it may be asked1 ,why is superphosphate so much more rapid in its action than insoluble phosphate2 or why should we be at the trouble and expense of dissolving the phosphate if it has to become insoluble again in the soil8 ,this question is one of very great importance1 for the answer to it furnishes1 in our opinion1 the key to the whole phosphate question4 ,when superphosphate is added to the soil1 being soluble in water1 it is soon dissolved and carried down by the rain into its pores1 and becomes thoroughly mixed with the soil-particles4 ,it is thus soon fixed in the soil1 beyond the risk of being washed away4 ,the result is1 that the phosphate is obtained in a state of division infinitely more minute than could ever be obtained by mechanical grinding1 and is1 further1 most intimately mixed with the particles of the soil4 ,it is this intimate mixture of the phosphate with the particles of the soil1 and its minute state of division1 that constitute the only reason for rendering superphosphate superior in its action to even the most finely ground insoluble phosphates4 ,this opinion is supported by the fact1 that although the chemist has imitated nature in this matter so far as to manufacture precipitated phosphate1 he has failed1 as a rule1 in getting as favourable results with it as with superphosphate4 ,although the mechanical state of division of the manufactured precipitated phosphate is probably as fine as that obtained by nature from the superphosphate1 it is impossible to obtain so intimate a mixture with the soil-particles1 and hence the results obtained are different4 ,for these reasons it will be easily seen that the rate of action of the superphosphate must always be quicker than that of any other form of phosphatic manure4 ,the phosphate is everywhere distributed in the soil4 ,the plant-roots are thus furnished with a continuous supply throughout their growth1 and micro-organisms1 which require for their development a supply of this necessary plant-food1 are propagated4 ,a regularity in the plant's growth is thus secured1 which is of great importance4 ,but while admitting this1 there are many cases in which this greater quickness of action does not render soluble phosphate the most economical form4 ,the nature of the crop1 as well as the nature of the soil1 may in many cases be such as to render the application of the cheaper insoluble phosphate more economical4 ,it is imperative that the early growth of some crops be hastened as much as possible by a ready supply of easily assimilable plant-food1 in order to enable them to successfully sustain the attack of certain pests to which they are liable to succumb4 ,this1 for example1 is notably the case with turnips4 ,in such a case there can be no doubt that the value of soluble phosphate to the young plants is very great1 as it enables them to survive this critical period4 ,action of ,superphosphate sometimes unfavourable4 ,but even in this case there may be other conditions which render insoluble phosphate a preferable manure4 ,such a case is where the soil is of a very light nature and is deficient in lime4 ,in this case the acid superphosphate1 not having the necessary base to combine with1 may prove even hurtful to the young plants4 ,according to the late ,dr ,voelcker1 a concentrated superphosphate may produce a smaller crop than a fertiliser containing only a quarter as much soluble phosphoric acid1 when applied to root-crops on sandy soils1 greatly deficient in lime4 ,cases such as the above1 however1 are extremely rare2 and we may say that1 in the case of root-crops generally1 superphosphate must be regarded as of special value4 ,application of ,superphosphate4 ,in any case1 superphosphate ought to be applied to a soil some time before it is likely to be assimilated by the plant1 in order to allow neutralisation of its acid character to be fully effected before the plant's roots come in contact with it4 ,thus ,professor ,s4 ,w4 ,johnson1 one of the greatest living ,american authorities1 states it as his opinion that recent investigations tend to show that soluble and reverted 7or precipitated7 phosphates are1 upon the whole1 about equally valuable as plant-food1 and of nearly equal commercial value4 ,but as ,sir ,john ,lawes1 in quoting ,professor ,johnson to the above effect1 remarks1 this opinion is based on an experience of ,american agriculture1 in which country soluble phosphate is chiefly applied to cereal crops1 while in this country it is chiefly applied to turnips4 ,in the case of cereal crops1 the importance of a speedy early growth is not so great1 as we have already pointed out1 as it is in turnips1 where the danger to the young plants from the ravages of the turnip-fly is such that the growth of even a day or two may make a very considerable difference4 ,value of ,insoluble ,phosphate4 ,a consideration of the action of superphosphate1 then1 throws a good deal of light on the conditions which determine the value of insoluble phosphates when applied to the soil1 and shows that the state of division1 intimacy of mixture with soil-particles1 and the nature of the soil1 are the determining factors4 ,insoluble phosphates1 as we shall have occasion to see when discussing basic slag1 have their best action on soils poor in lime and rich in organic matter4 ,tables have been drawn up with a view to furnishing a guide for the value of phosphoric acid in different manures4 ,in the ,appendix#bcb we give those of ,wolff for #ahic1 and an ,american table1 drawn up for #ahib4 ,the comparative values of mineral phosphates1 as well as ,peruvian guano and bone-dust1 will be further referred to in the following chapter4 ,rate at which ,superphosphate is applied4 ,the rate at which superphosphate is applied to the soil varies in different parts of the country4 ,in ,england #b to #c cwt4 per acre is considered an average dressing2 whereas in many parts of ,scotland it is applied in as large quantities as #f to #h cwt4 per acre to the turnip crop4 ,the reason why so much heavier dressings can be advantageously given in northern parts of this country is owing to the much longer period of unchecked growth4 ,in the more southern districts1 where the rainfall is less1 mildew is almost certain to appear when the sowing is as early as required for a maximum crop4 ,with it1 as with other manures1 the quantity must be determined by the conditions of its application1 and the amount of other manure applied4 ,,footnotes3 #bbe ,this holds true1 it may be mentioned1 with regard to the application of certain manures1 such as bone-char1 to the soil4 ,bone-char was for a long time used in ,france as a manure without being dissolved4 ,the action of such a manure1 containing a considerable percentage of carbonate of lime1 is slower than its action would be were it pure phosphate of lime1 as the carbonate of lime is first acted upon 7as in the case of superphosphate manufacture7 by the soil acids4 #bbf ,the solubility of tribasic phosphate1 of course1 is not always equal in different manures4 ,for example1 the phosphate in apatite1 owing to the crystalline structure of that mineral1 is not nearly so soluble as the phosphate in phosphatic guanos1 although in both cases its chemical composition is practically the same4 #bbg ,for formulae of the different phosphates1 see ,appendix1 ,note ,i41 p4 #cih4 #bbh ,for chemical formulae1 showing reaction1 see ,appendix1 ,note ,,ii41 p4 #cih4 #bbi ,of course it is well known that free phosphoric acid is obtained by acting upon phosphate of lime with an excess of sulphuric acid2 but the point above referred to as having been recently discovered is1 that when phosphate of lime is acted upon1 even by a small quantity of sulphuric acid1 free phosphoric acid is formed4 #bcj ,for chemical formulae showing this reversion1 see ,appendix1 ,note ,,iii41 p4 #cii4 #bca ,for chemical theories on reversion of soluble phosphate by iron and alumina1 see ,appendix1 ,note ,,iv41 p4 #cii4 #bcb ,see ,appendix1 ,note ,v41 p4 #djj4 ,,appendix ,,to ,,chapter ,,xiii4 ,,note ,i4 7p4 #chh74 ,the formulae1 and molecular and percentage composition1 of the different phosphates1 are given in the following table3-- ---------------------------------------- ------------------------------------ ,composition in terms of-- ---------------------------------------- ----- ,molecular weight4 ,per cent4 ---------------------------------------- ---------------------------- ,phos- ,phos- ,name4 ,symbol4 ,lime4,water4phoric,total4,lime4,water4p horic acid4 acid4 ---------------------------------------- ---------------------------- ,tri- or bone- #c;,ca,o1 phosphate4 ,p#b,o#e #afh #j #adb #caj #ed4ai #j4jj #de4ha ,bi- or di- #b;,ca,o1 ,h#b,o1 phosphate4 ,p#b,o#e #aab #ah #adb #bgb #da4ah #f4fa #eb4ba ,mono- or super-,ca,o1 #b;,h#b,o1 phosphate4 ,p#b,o#e #ef #cf #adb #bcd #bc4ic #ae4ci #fj4fh ---------------------------------------- ---------------------------- ,,note ,,ii4 7p4 #chh74 ,when sulphuric acid is added to tricalcic phosphate1 the following reaction takes place3-- 7#a47 #c;,ca,o1 ,p#b,o#e #b7;,h#b,o1 ,,so#c7 7,tricalcic phosphate71 7,sulphuric acid71 #b7;,ca,o1 ,,so#c7 ,ca,o1 #b;,h#b,o1 ,p#b,o#e 7,gypsum71 7,monocalcic phosphate74 7#b47 #c;,ca,o1 ,p#b,o#e #c7;,h#b,o1 ,,so#c7 #c;,ca,o1 ,,so#c #c;,h#b,o1 ,p#b,o#e1 or #b;,h#c,,po#d4 ,,note ,,iii4 7p4 #cij74 ,this equation gives the chemical reaction taking place when soluble phosphate is reverted1 owing to the presence of undissolved phosphate3---- #c;,ca,o1 ,p#b,o#e ,ca,o1 #b;,h#b,o1 ,p#b,o#e 7,tricalcic phosphate71 ,monocalcic phosphate1 #b;,ca,o1 ,h#b,o1 ,p#b,o#e #b;,ca,o1 ,h#b,o1 ,p#b,o#e 7,dicalcic phosphate71 7,dicalcic phosphate74 ,,note ,,iv4 7p4 #cij74 ,just what the reactions are which are produced by the iron and alumina compounds has never been made out very clearly4 ,but some idea of them may be gained from the following suggestions1 which were thrown out by the ,english chemist ,patterson4 ,suppose the sulphuric acid has dissolved a quantity of iron or alumina1 then we may have the reaction3---- ,fe#b,o#c1 #c,,so#c ,ca,o1 #b;,h#b,o1 ,p#b,o#e ,fe#b,o#c1 ,p#b,o#e ,ca,o1 ,,so#c #b7;,h#b,o1 ,,so#c71 and the free acid thus formed would proceed to dissolve more iron or alumina from the rock that had previously escaped decomposition1 and the reaction here formulated would occur again and again4 ,here we have a cumulative process continually increasing the quantity of insoluble ,fe#b,o#c1 ,p#b,o#e1 and diminishing in the same proportion the soluble ,p#b,o#e4 ,again1 we may have simply---- #b;,fe#b,o#c #c7;,ca,o1 #b;,h#b,o1 ,p#b,o#e7 #b7;,fe#b,o#c1 ,p#b,o#e7 #c;,ca,o1 ,p#b,o#e2 where three molecules of the soluble phosphoric acid are made to revert to the insoluble state at one blow4 ,in case the iron in the original rock were in the state of ferrous oxide1 perhaps the following reaction might occur3---- #d7;,fe,o1 ,,so#c7 #b,o ,ca,o1 #b;,h#b,o1 ,p#b,o#e #c;,ca,o1 ,p#b,o#e #b7;,fe#b,o#c1 ,p#b,o#e7 #d7;,ca,o1 ,,so#c74 ,in all these equations1 except the last1 alumina would serve as well as oxide of iron4--7,vide ,storer's ',agricultural ,chemistry1' vol4 i4 pp4 #bgf1 #bgg47 ,,note ,v4 7p4 #cif74 ,the following table shows the relative trade values of phosphoric acid in different manures3-- ,i4--,,wolff1 #ahic4 ,phosphate soluble in water 7as in super7 #ajj ,precipitated phosphate1 ,peruvian guano #ib ,reverted phosphate1 finest steamed bone-dust fish-guano1 poudrette #hc ,phosphatic guanos 7,baker ,island71 wood-ashes #ge ,coarser bone-dust1 powdered animal charcoal1 bone-ash #fg ,coarse fragments of bone1 powdered phosphorite and coprolite1 ,thomas-slag1 farmyard manure #cc ,,ii4--,,american1 #ahib4 ,phosphate soluble in water #ajj ,phosphate soluble in ammonium citrate #id ,fine bone-dust1 powdered fish #id ,fine medium bone #gd ,medium bone #fj ,coarse bone #dj ,,chapter ,,xiv4 ,,thomas-,,phosphate ,,or ,,basic ,,slag4 ,in this substance we have a most important addition to our phosphatic manures4 ,it has been in the market since #ahhf1 and the consumption alone in ,germany in #ahhg amounted to nearly #cjj1jjj tons4 ,in this country it is only now beginning to be used to any extent4 ,its ,manufacture4 ,thomas-slag is a bye-product obtained in the manufacture of steel by what is known as the basic process4 ,in the year #ahgi an improvement in the well-known ,bessemer process was patented by ,messrs ,gilchrist ,thomas4 ,it must be explained that in the manufacture of steel from pig-iron certain impurities in the raw material have to be got rid of in order to produce a good steel4 ,among these impurities one of the most important is phosphorus4 ,this is owing to the fact that even a very small percentage of phosphoric acid in steel has the effect of rendering it brittle4 ,the extraction of the phosphorus from the raw material was formerly1 however1 attended with very serious difficulties1 and had the effect naturally of rendering steel a costly article1 inasmuch as only the purer kinds of pig-iron could be used for the purpose4 ,by the introduction in #ahgi1 however1 of the ,thomas-,gilchrist or basic process1 these difficulties were very largely overcome1 and the employment of even such impure irons as the ,cleveland 7containing comparatively a large percentage of phosphorus7 was rendered possible1 and the price of steel consequently generally very much reduced4 ,the process consists of submitting the molten pig-iron to a very great heat in a pear-shaped vessel 7known technically as the converter74 ,this is open at the top1 and is supported on hinges1 which permit of its being moved so as to pour off the scum which rises to the surface at the end of the operation1 and which1 we may explain1 consists of basic slag4 ,in the original process the sides of the converter were lined with fire-bricks1 consisting largely of silica4 ,this process was known as the acid process4 ,in the ,thomas-,gilchrist process1 however1 the sides of the converter are lined with lime 7dolomitic limestone being largely used71 lime being also added to the pig-iron4 ,an air-blast is injected through the molten mass1 and the impurities are burnt1 or oxidised as it is chemically termed4 ,the phosphorus in the iron is thus converted into phosphoric acid1 and1 uniting with the lime1 forms phosphate of lime1 which rises1 as we have already said1 to the surface in the form of a scum1 and is separated from the steel by being poured off4 ,not at first used4 ,this1 then1 is how the ,thomas-slag is obtained4 ,it did not seem1 however1 for some years after the introduction of this ingenious process1 to have struck any one that this rich phosphatic bye-product might prove a valuable addition to our artificial fertilisers4 ,the result was1 that the ,thomas-slag was treated as another of the only too numerous valueless bye-products which seem to be necessarily incidental to most of our chemical and other manufactures1 and was allowed to accumulate in large quantities without being used for any purpose4 ,discovery of its ,value4 ,in #ahhc some short articles published in ,germany on the subject were the means of first drawing the attention of the public to its importance as a manure4 ,during the years #ahhd and #ahhe numerous experiments were carried out on the subject in the same country2 and from then up till the present hour it has become more and more extensively used in ,germany1 till in #ahhg1 as already stated1 its consumption amounted to nearly #cjj1jjj tons4 ,composition4 ,it consists mainly of phosphate of lime1 silicate of lime1 free lime1 free magnesia1 and oxides of iron and manganese4 ,its composition1 of course1 naturally varies2 but the following may be taken as an average analysis3#bcc-- ,per cent4 99,phosphoric acid #ag ,lime in combination with phosphoric1 silicic1 sulphuric1 and carbonic acids #dj ,free lime #ae ,oxides of iron #ab 99,equal to tricalcic phosphate #cg ,as a rule1 the phosphoric acid varies considerably1 ranging from #aj to #bj per cent--that is1 from #bb to #dd per cent tricalcic phosphate4 ,this is owing to the difference in the percentage of phosphorus in the raw material and the quantity of lime added4 ,attempts have been made in ,germany during the last two or three years to obtain a slag richer in phosphoric acid than that obtained heretofore1 and a process for this purpose has been patented by ,professor ,scheibler4 ,this consists of a slight modification in the ordinary process4 ,instead of treating the pig-iron with an excessive quantity of lime1 the amount added is not sufficient to effect the complete dephosphorisation of the iron4 ,the resulting slag is very rich in phosphoric acid1 and is correspondingly poor in iron4 ,the iron is then again treated with fresh lime1 and the phosphorus completely removed1 while the same lime may be used over again4 ,such slag forms a very much more concentrated phosphatic manure than the ordinary slag1 and is known as patent phosphate meal4 ,a point which not only renders the slag a product of peculiar interest from a chemical point of view1 but has a most important bearing on its value as a manure1 is the nature of the compound formed by the union of the lime with the phosphoric acid4 ,in the ordinary so-called raw phosphates1 such as bone-meal1 bone-ash1 coprolites1 c41 the lime and phosphoric acid are combined in the form of what is known1 in chemical phraseology1 as tribasic phosphate of lime4 ,that is to say1 that for every equivalent of phosphoric acid there are three equivalents of lime4 ,now it was naturally concluded at first that the tribasic phosphate was the form in which these two substances existed in the slag4 ,this1 however1 was found out not to be the case1 in the following way4 ,on allowing the slag to cool1 it was found that small but perfectly defined crystals were formed4 ,these crystals1 by careful analysis1 were shown1 first by ,hilgenstock1 to consist of a form of phosphate of lime hitherto unknown1 in which four equivalents of lime were combined with one equivalent of phosphoric acid1 and which was therefore called tetrabasic phosphate4 ,processes for preparing ,slag4 ,as soon as the idea of utilising the slag as a manure was suggested1 various plans for extracting its phosphoric acid1 and rendering it available as plant-food1 were devised4 ,these were deemed necessary1 it was thought1 by the very insoluble nature of the phosphates in the slag1 as well as by the supposed injurious action which would be exerted on plant-life by the protoxide of iron it contained4 ,accordingly1 a large number of patents were taken out1 covering almost every conceivable method for treating the slag1 whether practicable or not4 ,they all in the main are combinations or variations of the following processes3-- #a4 ,preliminary preparation of the ,slag4 7a7 ,by treating molten1 or otherwise1 with superheated steam1 or cooling when hot with water1 to reduce it to small pieces or to a fragile state4 7b7 ,grinding4 7c7 ,treating with water to wash out free lime1 or with sugar solution4 7d7 ,roasting in the air1 or with some oxidising agent4 #b4 ,solution of the ,slag4 7a7 ,completely in weak or strong acids 7hydrochloric1 sulphuric1 c47 7b7 ,partially1 so as to dissolve the phosphates and silicates of lime1 and leave most of the iron and manganese oxides4 #c4 ,precipitation of the phosphoric acid1 with lime or iron salts3 or1 ,processes in which the slag is smelted with charcoal1 to reduce phosphates to phosphides1 treated with acid1 and the phosphuretted hydrogen burnt to phosphoric acid2 and1 ,processes in which the slag is fused with soda or potash salts1--caustic1 chlorides1 sulphates1 carbonates1--with or without steam being forced through1 to form soluble alkaline phosphates4#bcd ,many of these processes were tried2 but it was found by experiment that the best and most economical way was by applying the slag direct to the ground in a state of very fine powder4 ,experiments further showed that it had not the injurious effect on vegetation which it was feared it would have from the protoxide of iron it contained4 ,the discovery that its phosphoric acid existed1 as has been already explained1 as a tetrabasic phosphate of lime1 has strengthened the opinion that this is the best method of application4 ,a good deal has been found to depend upon the fineness of the ground slag1 with the result that it is now commonly sold on a mechanical as well as a chemical analysis--i4e41 the slag is guaranteed to pass through a sieve of a certain fineness4 ,solubility of ,slag4 ,professor ,wagner of ,darmstadt has carried out some extremely interesting experiments on the solubility of slag4 ,he found that very finely powdered slag was dissolved in carbonic acid water to the extent of #cf per cent1 while1 similarly treated1 phosphorite only dissolved to the extent of #h per cent4#bce ,another very important solvent is citrate of ammonia4 ,reverted 7or precipitated7 phosphate is entirely soluble in it1 and phosphate soluble in it ought to be valued as worth more than that which is not4 ,now1 the solubility of ,thomas-slag in citrate of ammonia was found by ,professor ,wagner to be no less than #gd per cent1 while that of phosphorite only amounted to #d per cent4 ,these results were corroborated by ,professor ,s4 ,w4 ,johnson1 who found that of the #ai4hg per cent of phosphoric acid contained in a sample of basic slag1 no less than #ai4eg per cent was soluble in ammonium citrate1 while a finely ground sample of phosphatic rock yielded1 on analysis1 only #a4ha per cent soluble in citrate of ammonia1 of a total of #bi4di per cent phosphoric acid which it contained4 ,professor ,fleischer has also tested the comparative solubility of basic slag and phosphorite1 by boiling them in a solution of acetic acid4 ,the former was found to have been dissolved to the extent of #ai per cent1 while the latter to only #e per cent4 ,a highly interesting and most important experiment was performed by ,mr ,heinrich ,albert1 of ,biebrich4 ,one gramme of basic slag and #ajj grammes of peat were mixed together in a litre of water1 and it was found that1 after standing for fourteen days1 #gi per cent of the phosphoric acid contained in the slag was rendered soluble4 ,in the above experiments it was found that the fineness of grinding had a marked effect on the solubility of the slag1 and that the finer it was ground the greater was its solubility4 ,this has been further demonstrated in ,professor ,wagner's practical experiments4 ,from these it was found that finely ground slag has an action four times as quick as coarse slag2 but that1 as far as practical results were concerned1 there seemed to be a limit to the fineness to which it was advisable to grind the slag1 as slag above a certain fineness did not give better results than a coarser slag4 ,at any rate1 he found that slag of a fineness so great that it all passed through a gauze sieve1 gave no better results in his experiments than slag which left #ag per cent behind4 ,we may say1 however1 that the finer the slag is ground1 the greater will its activity as a manure be2 and that a certain degree of fineness is absolutely necessary to constitute it an active fertiliser4 ,as ,professor ,wagner's experiments are among the most valuable and complete carried out on basic slag1 we shall give a somewhat detailed account of them4 ,darmstadt ,experiments4 ,professor ,wagner's experiments were carried out on such different kinds of crops as flax1 rape1 wheat1 rye1 barley1 peas1 and white mustard1 and the object of the experiments was to ascertain the comparative activity as fertilisers of superphosphate1 basic slag of different degrees of fineness1 ,peruvian guano1 damped bone-meal1 and very finely ground coprolites4 ,in order to obtain a correct estimate of the relative value of these different forms of phosphatic manures1 it was necessary to render the nitrogen in the bone-meal and the nitrogen and potash contained by the ,peruvian guano inactive--i4e41 to limit the test strictly to phosphoric acid4 ,this was done by adding to the super1 basic slag1 and coprolites1 quantities of nitrogen and potash equal to those contained by the other manures4 ,there was further added to all the experiments 7the unmanured ones1 of course1 as well7 an excess of nitrogen and potash4 ,in this way the increase in returns could only be due to the phosphoric acid4 ,the general results obtained from these experiments may be summed up as follows3 ,taking the activity of super to be represented by #ajj1 then the relative activity of-- ,basic slag of ,no4 #abcf fineness is #fa ,basic slag1 ,no4 #bbcg #eh ,peruvian guano #cj ,basic slag1 ,no4 #cbch #ac ,bone-meal #aj ,coprolites #i ,from these results the value of the commercial article has been attempted to be ascertained4 ,as it contains #hj per cent or thereby of fine meal and #bj per cent of coarse1 its activity may be stated to be #ej1 or half as active as super4 ,thus #b cwt4 of basic slag is equal to #a cwt4 of super4 ,this only refers to the first year's effect4 ,professor ,wagner has made further experiments as to the after-effects of the different manures1 with the result that he has found that the after-effects of the basic slag are even better than those of the super4 ,this stands to reason1 for if twice as much phosphoric acid be added in the form of basic slag as is added in the form of super1 and the effect of the first year is similar--that is1 the same quantity of phosphoric acid is assimilated by the plant from the soil in both cases--there is naturally more phosphoric acid left behind in the soil manured with basic slag than in that manured with superphosphate of lime4 ,for example1 if #ajj lb4 of super has the same effect in the first year as #bjj lb4 of basic slag1 and it is found that only #fj lb4 of the super and the basic slag have been assimilated the first year by the plant1 it is only natural to conclude that the remaining #adj lb4 of the basic slag will have a better after-effect than the remaining #dj lb4 of super4 ,this has been actually proved to have been the case in ,professor's ,wagner's experiments4 ,the following are the results of some experiments which ,professor ,wagner has carried out on the after-effects of different manures3-- ,out of #ajj parts of phosphoric acid1 there was removed by the first year's crop-- ,super #fc ,peruvian guano #bb ,bone-meal #g ,coprolites #f ,thomas-meal-- ,no4 #a fineness #ci ,no4 #b #dc ,no4 #c #ae ,out of #ajj parts of phosphoric acid left by the first crop1 there was removed by the three succeeding crops-- ,super #cj ,peruvian guano #i ,bone-meal #ac ,coprolites #f ,thomas-meal-- ,no4 #a fineness #ad ,no4 #b #bi ,no4 #c #bd ,numerous other experiments have been carried out by various experimenters in different parts of ,germany which it is unnecessary to cite here4 ,none1 however1 are so complete as those of ,professor ,wagner4 ,results of other ,experiments4 ,in this country experiments have been carried out at ,rothamsted1 ,cirencester1 ,downton1 ,bangor1 and by ,dr ,aitken at the ,highland and ,agricultural ,society's stations1 as well as elsewhere4 ,the results of these various experiments naturally differ considerably1 this being owing to the difference in the nature of the soils upon which the experiments were carried out1 as well as the different degrees of fineness of the slag used4 ,they all1 however1 serve to confirm ,professor ,wagner's general results4 ,the results obtained in ,scotland by ,dr ,aitken at the ,highland ,society's stations were especially favourable to basic slag as a phosphatic manure4 ,the experiments were carried out on turnips1 and it was found that the ,thomas-slag was1 weight for weight1 superior to superphosphate4 ,it may be added that the slag used in these experiments was rich in phosphoric acid1 and was in an unusually fine state of division4 ,experiments carried out by the author have proved slag to be1 on various ,scottish soils1 one of the most economical phosphatic manures to apply to turnips4#bci ,we will sum up1 in conclusion1 the deductions which may be fairly drawn from the results of all the above-mentioned experiments as to the value of basic cinder as a manure4 ,soils most suited for ,slag4 ,although its action is undoubtedly more favourable on some soils than others1 it may be broadly stated that generally its phosphoric acid is half as valuable as that in soluble phosphate4 ,the soils on which it will have the most marked effect will be those of a peaty nature1 poor in lime1 but rich in organic matter4 ,the beneficial results obtained by an application of lime to peaty soils are well known4 ,as the slag contains a large percentage of free lime1 it thus performs on such soils a double function4 ,on meadow-lands1 all kinds of pasture-lands 7if not of too dry a character71 and clay soils poor in lime1 its action has been shown to be especially favourable4 ,of different kinds of crops1 those best suited to benefit from the slag as a phosphatic manure are those of the leguminous kind4 ,this arises from the fact that their period of growth is longer than that of most other crops4 ,rate of ,application4 ,as to the rate per acre at which the slag ought to be applied1 there will naturally be a difference of opinion4 ,professor ,wrightson1 of ,downton ,agricultural ,college1 recommends that it should be applied at the rate of from #f to #aj cwt4 per acre4 ,this1 of course1 is very liberal manuring4 ,we must remember1 however1 that phosphatic manures1 unlike nitrogenous manures1 and to some extent potash manures1 may be applied in even excessive quantities without any risk of loss4 ,it is impossible to measure out our phosphate manures in the same accurate manner as we measure out our nitrogen4 ,it is safer1 therefore1 and on that account more economical in the long-run1 to apply our phosphate in excessive quantity than the reverse4 ,the reason of this may be shortly explained4 ,the phosphoric acid which is naturally present in most soils is with difficulty soluble4 ,only a small quantity is yielded daily to the plant4 ,this quantity may1 under favourable climatic conditions1 be sufficient2 but these favourable influences never last very long at a time4 ,for three weeks1 perhaps1 the plant may experience drought1 and during this period it takes up no phosphoric acid1 and its growth practically comes to a standstill2 but this period of drought is followed by rain and warm weather1 and the plant1 if it is to be ripe by harvest-time1 must make up for lost time4 ,it must grow as much the next few days under these favourable climatic conditions as it would have grown under normal conditions in double or treble the time4 ,in order to do so1 however1 it must be able to obtain plenty of phosphoric acid1 and this is only possible where there is a decided excess of phosphoric acid present in the soil4 ,the richness of a soil1 therefore1 in phosphoric acid1 must be such that it is not only able to supply the ordinary wants of the plant1 but to provide an excess when such an excess will be needed2 for one must remember that the amount of plant-substance formed in the course of a few days under favourable conditions is very great1 and that the amount consequently of phosphoric acid which plants assimilate during that period must also be very considerable4 ,method of ,application4 ,in conclusion1 as to the method of application of the slag1 agriculturists must be warned against mixing it with sulphate of ammonia2 for if this is done1 a considerable loss of ammonia will ensue1 set free from the sulphate by the action of the free lime which the ,thomas-slag contains4 ,with nitrate of soda and potash salts it may be freely mixed4 ,such mixtures1 however1 are apt to form themselves into little balls1 which soon become very hard4 ,they should therefore only be mixed shortly before use4 ,to overcome this difficulty1 ,professor ,wagner recommends the mixture of a little peat or sawdust with the slag4 ,,footnotes3 #bcc ,see ,appendix1 p4 #dag4 #bcd ,vide paper on ,basic ,slag3 ,its ,formation4 ,by ,stead and ,ribsdale4 ',journal of the ,iron and ,steel ,institute1' #ahhg1 p4 #bcj4 #bce ,vide ,professor ,wagner's pamphlet1 ',der ,duengewerth und die rationelle ,verwendung der ,thomas ,schlacke1' ,darmstadt1 #ahhh4 #bcf ,no4 #a fineness was such as passed entirely through a fine gauze sieve of #bej wires to the linear inch4 #bcg ,no4 #b fineness was such as passed entirely through the regular standard sieve--i4e41 containing #abj wires to the linear inch4 #bch ,no4 #c was what would not pass through the standard sieve4 #bci ',transactions of the ,highland and ,agricultural ,society1' #ahia2 ',chemical ,news1' #ahic4 ,,appendix ,,to ,,chapter ,,xiv4 ,,note 7p4 #djd74 ,for those more particularly interested1 we append a full analysis of the slag1 taken from ,messrs ,stead and ,ribsdale's paper in the ',journal of the ,iron and ,steel ,institute1' #ahhg1 vol4 i4 p4 #bbb3-- ,lime #da4eh ,magnesia #f4ad ,alumina #b4eg ,peroxide of iron #h4ed ,protoxide of iron #ac4fb ,protoxide of manganese #c4gi ,protoxide of vanadium #a4bi ,silica #g4ch ,sulphur 4#bc ,calcium 4#ca ,sulphuric anhydride 4#ab ,phosphoric acid #ad4cf ----- #ii4ic ,,chapter ,,xv4 ,,potassic ,,manures4 ,relative ,importance4 ,in ,chapter ,,vi4 we pointed out that of the three manurial ingredients potash was the one most abundantly occurring1 and that1 consequently1 the necessity of adding it in the form of an artificial manure existed less frequently than in the case of nitrogen or phosphoric acid4 ,it was further pointed out that1 under the ordinary conditions of agriculture1 a greater restoration to the soil of the potash removed in the crops was made in the straw used in farmyard manure than was the case with regard to the other two ingredients4 ,despite these facts1 there are many cases where the addition of potassic manures is of the highest importance in increasing plant-growth4 ,it will be well1 therefore1 to devote a little space to considering our different potassic manures and their respective action4 ,scottish ,soils supplied with ,potash4 ,potassic manures are not so valuable in this country since experience has shown that most ,scottish soils are abundantly supplied with this manurial ingredient4 ,moreover1 under the conditions of most ,european farming1 there seems to be a steady gain to the soil of potash4 ,in ,america1 however1 the action of potash as a manure seems to be more strikingly illustrated4 ,indeed1 wherever forage crops or straw are sold off the farm in large quantities1 or where beets1 cabbages1 carrots1 potatoes1 onions1 c41 are also grown in large quantities1 the necessity for potash manuring generally arises4 ,sources of ,potassic ,manures4 ,the value of potash as a manure first came to be recognised from the favourable action of wood-ashes4 ,of course their favourable action is not due solely to potash1 as they contain1 in addition to the other ash ingredients of the plant1 phosphates2 and their value as a manure may also be said to depend not a little on their indirect action4 ,they contain a certain percentage of caustic alkali1 which promotes the decomposition of the nitrogenous matter of the soil4 ,but making due allowance for these other valuable properties1 the chief value of wood-ashes is undoubtedly due to the potash they contain4 ,hence the use of the commercial article called potash1 which is a mixture of potassium carbonate and hydrate1 and which is obtained from wood-ashes1 was formerly common to a considerable extent as a manure1 especially for clover4 ,barilla1 a rich potassic manure prepared by burning certain strand plants1 especially the saltwort1 was also in the past largely exported from ,sicily and ,spain4 ,kelp1 a product got by burning sea-weed in ,scotland1 is also a rich potassic manure4 ,since1 however1 the discovery of the ,stassfurt mines1 all potassic manures have come from these4 ,stassfurt ,potash ,salts4 ,huge salt deposits exist at ,stassfurt in ,germany4 ,they have been formed by the evaporation of an inland sea4 ,salt was first discovered in these deposits in #ahci1 but for long the presence of potash salts was little suspected1 and it was not until #ahfb that the potash salts were worked4 ,we have already1 in the ,appendix to ,chapter ,,vi41 given a list of the chief potash minerals occurring in the ,stassfurt deposits4 ,these minerals are found in layers1 the lowest layer consisting of almost pure salt2 while immediately above this we have a layer of salt mixed with the mineral polyhallite 7containing potassium sulphate7 of about #ajj feet thick4 ,above this last layer there is a layer of about #ij feet1 containing kieserite 7magnesium sulphate7 mixed with potassium and magnesium chlorides2 and above this again is a layer 7#ij feet7 of carnallite1 which furnishes the chief source of the potash salts used for manurial purposes4 ,at first the crude salts1 as obtained direct from the deposits1 were sold as manures under the name of ,abraum salts4 ,now1 however1 they are purified4 ,of potash salts in #ahhh some #be1jjj tons were exported from ,stassfurt for manurial purposes4 ,of these salts there may be mentioned1 viz41 kainit1 an impure form of the sulphate1 containing on an average about #ab per cent of potash1 and the muriate and the sulphate--both salts1 in a more or less pure form1 being used4 ,a word or two may be added on the effect of the two forms of potash--viz41 as the sulphate and as the muriate4 ,relative ,merits of ,sulphate and ,muriate of ,potash4 ,it is a well-known fact that muriate of potash1 far from having a beneficial effect on certain crops1 is actually harmful4 ,of these1 sugar-beets1 potatoes1 and tobacco may be mentioned4 ,in the case of beets it seems to have an effect in lessening the percentage of crystallisable sugar1 while potatoes are rendered waxy4 ,with regard to the tobacco-plant1 it seems to impair the value of the leaf from the smoker's point of view4 ,that this deleterious action is due to the form in which the potash is present1 and not to the potash itself1 seems to be pretty clear1 since potash in the form of sulphate has not this deleterious effect on these plants4 ,another objection which has been urged against muriate of potash is that1 when applied as a manure1 it is apt to give rise to the formation of calcium chloride1--a compound which is distinctly hurtful to many plants4 ,a similar charge cannot be brought against sulphate of potash1 since gypsum1 which is the chief compound it is likely to give rise to1 is of much value1 as we have already pointed out1 as an indirect manure4 ,on the whole1 therefore1 sulphate of potash seems to be the safest form in which to add potash4 ,unfortunately1 however1 most of the commercial sulphates are very impure1 and contain generally considerable quantities of muriate4 ,in favour of the muriate1 it may be said that it is the more concentrated manure1 and that it diffuses better in the soil than the sulphate--a point of great importance4 ,it has1 moreover1 been used without any bad effect for clover1 corn1 grass1 and some root crops4 ,application of ,potash ,manures4 ,the extreme tenacity with which the soil-particles fix potash salts1 when applied as manures1 is a point which ought to be borne in mind in their application4 ,this1 as we have just noticed1 is greater in the case of the sulphate than in the case of muriate1 and it has been observed that certain other fertilisers seem to exercise a considerable influence in hindering their fixation4 ,among these may be mentioned bone-meal and farmyard manure4 ,nitrate of soda also seems to increase the diffusibility of potash salts4 ,conversely1 potash salts seem to help to fix ammonia4 ,for the above reasons potash manures ought to be applied to the soil a considerable period before they are likely to be used by the crop4 ,there is little risk of any serious loss taking place owing to rain4 ,autumn application is generally recommended4 ,even in very light soils it has been proved in the ,norfolk experiments that autumn application has an immense advantage over spring application4 ,it has been found that where potash is applied as sulphate1 little sulphuric acid is absorbed by the plant4 ,soils and ,crops suited for ,potash ,manures4 ,of soils best suited for potash manures1 it has been found that light soils1 and those largely charged with peaty organic matter 7such as the moorland soils of ,germany71 are most benefited2 while on heavy clayey soils the percentage of potash which these latter contain is already sufficiently abundant for the needs of plants4 ,at ,flitcham the value of potash on chalk soils has been strikingly demonstrated4 ,of crops1 it is now pretty generally acknowledged that those of the leguminous order are most benefited by potash4 ,especially in the case of clover has potash always proved itself a manure worth applying4 ,rate of ,application4 ,potash is best applied in small quantities4 ,from #a to #b cwt4 of the muriate or sulphate is a common amount1 and from #f to #h cwt4 of kainit4 ,,chapter ,,xvi4 ,,minor ,,artificial ,,manures4 ,in addition to the manures which have been discussed in previous chapters1 there are a number of minor manures which are used to a very much smaller extent--dried blood1 hoofs1 horns1 c4 ,among these one of the most valuable is dried blood4 ,fresh blood1 containing #hj per cent of water1 has from #b4e to #c per cent of nitrogen1 about 4#be per cent of phosphoric acid1 and about 4#e per cent of alkalies4 ,when dried it forms a very concentrated and valuable nitrogenous manure1 which has long been used in ,france4 ,the commercial article contains1 on an average1 about #ab per cent of nitrogen1 and slightly over #a per cent of phosphoric acid4 ,when mixed with the soil it ferments1 and the nitrogen it contains is converted into ammonia4 ,although not so quick-acting a manure as nitrate of soda or sulphate of ammonia1 it can by no means be described1 as is done in ordinary agricultural text-books1 as a slow-acting manure4 ,its nitrogen may be regarded as of equal value to that in ,peruvian guano4 ,it is peculiarly suited for horticulture1 and is chiefly used in this country as a manure for hops4 ,it has also been used with beneficial results for wheat1 grass1 and turnips4 ,as a manure it is best suited for sandy or loamy soils4 ,considerable quantities are exported to the sugar-growing colonies as a manure for sugar-cane4 ,manures are made from other animal refuse4 ,it may be mentioned that lean flesh 7containing #ge per cent of water7 has about #c to #d per cent of nitrogen14#e per cent of alkalies1 and 4#e per cent of phosphoric acid2 that is to say1 a ton of lean flesh would contain about #gj lb4 of nitrogen and #aj lb4 of phosphoric acid4 ,in air-dried flesh1 according to ,payen and ,boussingault 7containing #h-a_/b per cent of moisture71 there is #ac per cent of nitrogen4 ,flesh1 therefore1 is1 when properly composted1 a valuable nitrogenous manure4 ,dried flesh is generally made into a manure called meat-meal guano1 the composition of which we have already referred to in the chapter on ,guano4#bdj ,hoofs1 horns1 hair1 bristles1 and wool1 wool-waste and the intestines of animals1 have been used as manures4 ,hoofs and horns form a regular source of artificial nitrogenous manure2 the latter being obtained as a bye-product in the manufacture of combs and other articles4 ,they are in the form of a fine powder2 and in order to increase their rate of action1 which is very slow1 they are often composted in ,america with horse-manure before use4 ,they have also been composted with slaked lime4 ,there can be no doubt that such treatment increases very considerably their value4 ,their percentage of nitrogen seems to vary very much according to the kind of animal from which they are derived4 ,in nine samples of horn the nitrogen was found to vary from #g-a_/b to #ad-a_/d per cent2 giving an average of #aa-a_/c per cent4 ,the nitrogen seems rarely to exceed #ae per cent4 ,the amount of phosphoric acid they contain has been found by various investigators to range from #f to #aj per cent4 ,s4 ,w4 ,johnson found only from 4#jh to 4#ae per cent in buffalo-horn shavings4 ,in ,france what is known as torrefied horn has been used4 ,this is horn which has been subjected to the action of steam4 ,the nitrogen in this material is considered to be more active than in ordinary horn4 ,according to ,way1 horns have been used for the hop crop with good results4 ,ground hoof is very similar in composition to horn1 and contains about #ad to #ae per cent of nitrogen4 ,considerable quantities are now used4 ,it must be remembered1 however1 that horns1 hoofs1 hair1 bristles1 c41 although rich in nitrogen1 possess a comparatively low manurial value4 ,the home production of these articles may be estimated at #fjjj to #gjjj tons4 ,scutch4 ,scutch is the name given to a manure made from the waste products incidental to the manufacture of glue and the dressing of skins4 ,it contains about #g per cent of nitrogen1 and is manufactured in ,london to the extent of several thousand tons annually4 ,shoddy and ,wool-waste4 ,shoddy1 which is a manure made from waste-wool products1 is a material largely manufactured in this country1 and which was formerly 7it is now used to a considerably less extent7 used to a large extent as a manure4 ,its annual production amounts to about #ab1jjj tons4 ,there are three qualities1--the first containing #h to #ab per cent of nitrogen2 the second1 #f to #h per cent2 and the third1 #e to #h per cent4 ,shoddy is by no means a very valuable manure4 ,woollen-waste products were formerly much richer in nitrogen than is now the case4 ,this is due to the fact of the adulteration with cotton1 now so prevalent in the manufacture of woollen goods4 ,pure woollen rags should contain #ag to #ah per cent of nitrogen4 ,it has been strongly recommended to treat woollen waste with caustic alkali before being used as a manure1 in order to render their nitrogen more quickly available2 and there is a good deal to recommend this treatment4 ,when wool-waste is applied as a manure1 it should in every case be in autumn1 so as to allow as long a period as possible to elapse before it is required for the plant's growth4 ,leather has also been used as a manure4 ,its nitrogen may be stated at from #d to #f per cent2 and it may safely be described as of all materials used as nitrogenous manures the least valuable4 ,leather is1 from its very nature1 admirably adapted to resist decomposition when applied to the soil1 and unless it is reduced to a very fine condition1 might be trusted to remain undecomposed for a long period4 ,torrefied leather1 however1 is probably of greater value4 ,it is obtained in the same way as torrefied horn1 already referred to--namely1 by treatment with steam4 ,the grease and fatty matters which so largely aid it in resisting decomposition being extracted1 it is much better suited for manurial purposes than ordinary leather4 ,torrefied leather contains from #e to #h per cent of nitrogen4 ,soot4 ,a manure which has long been used and highly esteemed is soot4 ,obtained in the usual way1 it generally contains some #c per cent of nitrogen1 chiefly in the form of sulphate of ammonia1 and small quantities of potash and phosphates4 ,a varying proportion of the nitrogen is present in the form of ammonia salts2 and this undoubtedly confers upon soot its manurial value4 ,it has long been used as a top-dressing for young grain and grass1 and has been applied at the rate of from #dj to #fj bushels per acre4 ,it has an indirect value as a slug-destroyer4 ,many of the above-mentioned manures1 of comparatively low value1 will probably be less used in the future than they have been in the past1 owing to the more abundant supplies of nitrate of soda and ammonia salts which are now available4 ,many of these substances have probably been used in mixed manures4 ,,footnotes3 #bdj ,see p4 #cbd4 ,,chapter ,,xvii4 ,,sewage ,,as ,a ,,manure4 ,the value of sewage as a manure has been in the past enormously overrated1 and much misunderstanding has existed on the part of the public on the question of the profitableness of the disposal of town sewage as an agricultural manure4 ,not a few of the erroneous opinions prevalent in the past regarding sewage have been due to statements made by scientific and other writers as to the enormous wealth lost to the world by many of the present methods of sewage disposal4 ,fortunately1 however1 the sewage question is now increasingly regarded as a question1 in the first instance1 of sanitary interest4 ,as much has been written on the subject1 and many schemes have been devised1 at the expense of much ingenuity1 for utilising its manurial properties1 it may be desirable here to say a few words on the purely agricultural side of the question4 ,the two most important points about sewage are its enormous abundance and its extremely poor quality4 ,if the most important consideration were not the sanitary one1 but its manurial value1 then indeed our water system1 so universally used in towns1 must be regarded as a most wasteful one2 for by its means the value of the excrementitious matter from which it derives its manurial ingredients is tremendously lessened4 ,when we reflect that a ton of sewage1 such as is produced in many ,european cities1 contains only #b or #c lb4 of dry matter1 and that the total amount of nitrogen in this is only an ounce or two1 while the phosphoric acid is considerably less1 and that it is on those two ingredients that its value as a manure entirely depends1 we see very strikingly how poor a manurial substance sewage is4 ,various methods have been devised and experimented with for extracting these manurial ingredients1 and many methods are in operation in different parts of the world4 ,the methods of utilising sewage for agricultural purposes may be broadly divided into two classes4 ,irrigation4 ,one of these1 which may be classed under the heading of irrigation1 consists in pouring the sewage on to certain kinds of coarse green crops4 ,sometimes the land is made to filter large quantities of sewage by special arrangements of drains and ditches4 ,the land is first carefully and evenly graded down a gentle incline4 ,at the top of the field the sewage is conducted along an open ditch from which it is permitted to escape1 by the force of gravity1 by several smaller ditches running at right angles from the main ditch4 ,by means of stops which may be shifted at will1 the sewage can be directed to flow over different parts of the field4 ,modifications in this plan may be made so as to suit the nature of the ground4 ,in the case1 for example1 of a steep incline1 the field may be sewaged by means of what are known as catch-work trenches running horizontally along the hill4 ,in this way the sewage is allowed to pass over the whole of the field1 and is caught at the bottom in a deep ditch1 whence it is allowed to flow into the nearest river or stream4 ,this is the system which has been employed at the famous ,beddington ,meadows1 near ,croydon4 ,another method of distributing the sewage is by means of underground pipes1 which are laid in a sort of network over the ground to be manured4 ,at certain intervals pipes with couplings for hose are fitted on1 and by keeping a certain amount of pressure on the main pipes the sewage may be distributed over the different parts of the field as it is required4 ,a third modification is subsoil irrigation4 ,this resembles the last-named system1 with this difference1 that the pipes used are either porous or perforated with small holes4 ,total submersion can only be applied in the case of absolutely level lands1 and is practised to an enormous extent in ,piedmont and ,lombardy4 ,there has been little dispute as to the thorough efficiency of irrigation--when conducted under favourable conditions--as a method of purifying sewage and utilising to the full its constituents of manurial value4 ,it is the only method which has been conclusively shown to extract from sewage that to which it owes most largely its value as a manure--viz41 ammonia2 and from this fact it deserves a first place in the consideration of agriculturists4 ,for however admirable other methods may be from a sanitary point of view1 it is obvious that a method which would allow the ammonia in sewage wholly1 or at least to over #ij per cent1 to be lost1 cannot claim the same place in the judgment of agriculturists as a method which can extract for the soil not only the whole of this valuable constituent1 but all else in the sewage which in any way is of value to plant-life4 ,effects of continued ,application of ,sewage4 ,when sewage is continuously applied to the same land1 what generally takes place is this3 ,at first the sewage is purified1 and the soil derives corresponding benefit from the valuable fertilising ingredients it thus extracts4 ,after a time1 however1 the land becomes what has been termed sewage-sick4 ,the pores in the soil become choked up by the slimy matter the sewage contains in suspension2 the aeration of the soil1 which1 as we have already mentioned1 is so necessary1 is consequently to a large extent stopped2 and the result is1 that the land rapidly deteriorates1 and the sewage is no longer purified4 ,intermittent ,irrigation4 ,this is obviated to some extent by intermittent irrigation4 ,the land1 instead of receiving sewage continuously1 only receives it at intervals1 and is allowed some time to recover between each dose4 ,it is1 however1 the opinion of those who have given the subject much attention1 that land1 even although intermittently sewaged1 never recovers its original efficacy4 ,irrigation1 therefore1 under favourable conditions1 is a most successful method of utilising the manurial value of sewage2 but the great difficulty in practice is to obtain those favourable conditions4 ,it has long been known that if soil is properly to discharge its function as a purifier of sewage water1 it must be properly aerated2 and we now know that in every fertile soil the process of nitrification must be permitted free development4 ,now the application of large quantities of sewage to a soil is apt to prevent this free development4 ,as we have already seen1 absence of air and the lowering of the temperature of the soil distinctly tend to retard nitrification2 and these two conditions accompany the application of large quantities of sewage4 ,crops suited for ,sewage4 ,another objection to irrigation has been found in the alleged limited number of crops sewaged land is suited to yield4 ,it has been repeatedly stated that rye-grass is about the only crop it is profitable to grow on it4 ,in opposition to this statement1 however1 is the opinion expressed in the conclusions arrived at by the committee appointed by the ,british ,association for the consideration of the sewage question4 ,a vast number of experiments were carried out by them between the years #ahfh-gb1 and the result they arrived at was as follows3 ,it is certain that all kinds of crops may be grown with sewage1 so that the farmer can grow such as he can best sell2 nevertheless1 the staple crops must be cattle food1 such as grass1 roots1 c41 with occasional crops of kitchen vegetables and of corn4 ,while1 therefore1 it is probably a mistake to say that rye-grass is the only crop sewaged land is capable of growing profitably1 the bulk of experience goes to show that such a crop is best suited for such land4 ,this being so1 the question naturally arises1 ,what is the farmer who uses sewage as a manure to do with the large green crops he obtains from his land8 ,he is1 in most cases1 unable to use them himself or dispose of them at the time4 ,and while this has hitherto proved to be a most important drawback1 now that we have in ensilage a means of preserving our green crops in a condition suitable as fodder for as long a time as is necessary1 the grounds on which this objection rests are almost entirely removed4 ,it will be obvious1 of course1 that some soils are naturally much better fitted to perform purification of sewage than others2 but it must be frankly admitted that even the best of soils can only deal with a certain quantity of sewage4 ,various calculations have been indulged in as to the amount of sewage an acre of land can successfully deal with4 ,according to one of these1 an acre can purify some #bjjj gallons per day1 or that produced by #ajj persons2 while other calculations estimate it at #fj persons2 and others1 again1 at #aej4 ,the capacity of a sandy soil in this respect will be much greater than that of a heavier soil2 and at ,dantzic an acre of the sand-dunes is regarded as being capable of purifying the sewage of #fjj persons4 ,the late ,dr ,wallace has calculated that1 in order to treat the sewage of ,glasgow1 over twelve square miles of land would be required4 ,of course1 if the sewage is subjected to previous treatment1 which is often the case1 by the method immediately about to be described--namely1 precipitation--the amount of sewage the soil is capable of purifying will be correspondingly increased4 ,a difficulty which may also be pointed out in connection with irrigation as a means of disposing of sewage1 is the impossibility of carrying it on during frosty weather1 when the land is frost-bound4 ,in warm climates irrigation has much to recommend it as a means of sewage disposal4 ,in damp and cold climates1 on the other hand1 there are many objections4 ,treatment of ,sewage by ,precipitation1 c4 ,we now come to consider the methods grouped under this second heading4 ,mechanical filtration1 of course1 only aims at purifying sewage to the extent of removing all insoluble suspended matter which it contains4 ,different substances have been used as filters1 the most generally used being charcoal4 ,charcoal mixed with burnt clay1 gravel1 sand1 c41 has also been used4 ,in chemical precipitation1 however1 we have a method which claims to do more4 ,beyond the extracting of all solid matters in suspension1 it removes 7at any rate most chemical precipitants do7 nearly all the phosphoric acid1 which1 next to the ammonia1 is the most valuable constituent the sewage contains4 ,of all precipitants1 lime has been the most universally used2 and on the whole1 it is perhaps the best1 for it is both cheap and obtainable almost anywhere4 ,according to an analysis by the late ,professor ,way1 the difference in the percentages of phosphoric acid1 potash1 and ammonia1 before and after treatment with lime1 in a sample of sewage1 was as follows3-- ,grains per ,gallon4 ,before4 ,after4 ,phosphoric acid #b4fc 4#de ,potash #c4ff #c4hj ,ammonia #g4dh #g4ej ,from the above we see that while sludge caused by lime as a precipitant contains nearly all the phosphoric acid1 there is not a trace of the potash or ammonia removed4 ,sulphate of alumina has also been used1 both alone and in conjunction with lime4 ,the advantage claimed by it over lime is1 that the resulting precipitate is much less bulky4 ,in other respects1 however1 it does not seem to be any more efficient as a precipitant4 ,in the well-known ,a1 ,b1 ,c process1 a mixture of alum1 clay1 lime1 charcoal1 blood1 and alkaline salts1 in different proportions1 has been used4 ,this mixture is said to extract1 in addition to the phosphoric acid1 a certain proportion of the ammonia2 but the amount is so small as scarcely to be worth considering4 ,numerous other chemical substances have been used1 alone and also in conjunction with one another1 such as perchloride of iron1 copperas1 manganese1 c4 ,all alike1 however1 have failed to do more than effect partial purification1--the best results1 it may be added1 being obtained when the sewage thus treated was fresh4 ,with regard to the manurial value of the resulting sludges1 much difference of opinion has existed4 ,the small percentage of phosphoric acid and nitrogen they contain has prevented them from being used to any extent as a manure1 as their value did not admit of carriage beyond the distance of a few miles4 ,by the introduction a few years ago of the filter-press1 their value has been considerably enhanced4 ,the old method of dealing with the sludge at precipitation-works was to allow it to dry gradually by exposure to the atmosphere4 ,the result1 however1 of leaving sewage-sludge with over #ij per cent of water in it to dry in the air1 was to encourage the rapid decomposition and putrefaction of its organic matter1 so that in many cases the decomposing sludge proved to be as great a nuisance as the unpurified sewage itself would have been4 ,by the use of ,johnson's filter-press1 however1 a sludge containing #ij per cent of water was at once reduced to #ej per cent or even less4 ,by this means the percentage of its valuable constituents was very much increased1 and the sludge-cake1 besides being much more portable1 was neither so objectionable nor so liable to decomposition as before4 ,value of ,sewage-sludge4 ,as to the value of this sludge-cake as a manure1 we are happily in possession of some very interesting and valuable experiments by ,professor ,munro of ,downton ,agricultural ,college4 ,the sludge experimented upon was that produced by sulphate of alumina1 lime1 and sulphate of iron1 and contained1 after being subjected to ,johnson's filter-press1 from 4#f to 4#i per cent of nitrogen1 and over #a per cent of phosphoric acid4 ,it was found that the benefit resulting from the application of the sludge was far from what in theory might have been expected4 ,the experiments were made with turnips2 and the results obtained with superphosphate and farmyard manure respectively1 in the same field and under exactly the same conditions1 were contrasted with those obtained with sludge4 ,thus it was found that #ec lb4 of phosphoric acid as superphosphate1 or #fj lb4 as farmyard manure1 produced a considerably larger crop than #bdj lb4 of phosphoric acid in the sludge4 ,that is to say1 that the phosphoric acid in the sludge did not exert more than one-fifth of its theoretical effect4 ,the explanation of this somewhat strange result ,dr ,munro finds in the unsuitable physical character of the sludge-cakes4 ,in farmyard manure we have a loose texture and a large amount of soluble constituents when well rotted4 ,it thus quickly distributes its fertilising elements throughout the soil4 ,in the case of the sludge1 on the other hand1 its composing particles are closely compacted together1 and thus offer the greatest resistance to mechanical and chemical disintegration4 ,as a matter of fact1 says ,dr ,munro1 the sludge-plots in my experimental series were all readily identified1 when the roots were pulled1 by the presence of unbroken and undecomposed clods of cake1 which had evidently given up1 at most1 a small portion of their valuable ingredients to the soil4 ,briefly stated1 therefore1 the objections to chemical precipitation as a means of dealing with sewage are these--viz41 that while it relieves sewage of all its organic matter1 and to a large extent of its phosphoric acid1 it fails to extract any ammonia1 which is thus lost2 that the resulting sludge is consequently so poor in fertilising matters as scarcely to make it worth while to remove it any distance for manuring purposes2 and that1 further1 owing to its unfavourable physical character1 as at present made1 even the small percentage of plant-food it contains is not realisable1 within1 at any rate1 anything like a reasonable time1 to its full theoretical extent4 ,the most profitable method of treating sewage must be determined by various local conditions2 and it must be clearly understood that the question of sewage disposal is primarily a sanitary one1 and that it must be dealt with from the sanitary aspect4 ,the most profitable way of applying sewage as a manure1 however1 will doubtless be found by combining chemical precipitation and land irrigation4 ,,chapter ,,xviii4 ,,liquid ,,manure4 ,the adoption of irrigation as a means of utilising sewage1 suggests a short consideration of the value of liquid manures4 ,it has been a custom on many farms to apply the liquid manure got from the oozings of manure-heaps1 the drainings of the farmyard1 byres1 stables1 piggeries1 c41 directly to the soil4 ,indeed1 so strongly has the belief in the superiority of liquid manure over other manure been held by certain farmers1 that they have washed the solid animal excreta with water1 in order to extract from it its soluble fertilising constituents4 ,the late ,mr ,mechi was one of the foremost exponents of the value of liquid manure4 ,his farm of ,tiptree ,hall was fitted up with iron pipes for the distribution of the manure over the different fields4 ,superphosphate1 it may also be added1 as first made from bones by ,baron ,liebig1 was applied in a liquid form4 ,as to the general merits of liquid manure1 there can be no doubt that it is the most valuable form in which to apply manure4 ,it secures for the manurial ingredients it contains a speedy and uniform diffusion in the soil2 but1 on the other hand1 the expense of distributing it makes its application far from economical4 ,the chief ingredient in liquid manure is urine4 ,now the removal of urine from the farmyard manure-heap entails a severe loss of the ingredient which is most potent in promoting fermentation4 ,separation of the urine from the solid excreta is on this very account not to be recommended4 ,urine1 when applied alone1 is lacking in phosphoric acid1 of which it contains mere traces4 ,it is not1 therefore1 suitable as a general manure4 ,it has to be pointed out1 however1 that the drainings from a manure-heap in this respect are superior to pure urine1 since they contain the soluble phosphates washed out of the solid excreta4 ,the objections against using liquid manure may be summed up as follows3-- ,first1 it is too bulky a form in which to apply the manure1 and hence too expensive2 secondly1 it is not advisable to deprive the solid excreta of the liquid excreta1 as the one supplements the other2 thirdly1 fermentation is largely fostered in the solid excreta by the presence of the liquid excreta--hence fermentation will not take place properly in the solid excreta when deprived of the liquid excreta4 ,if1 however1 the production of liquid manure on the farm is in excess of what can be used for the proper fermentation of farmyard manure1 it will be best to utilise it for composts4 ,no better addition to a compost can be made than liquid manure1 as it induces speedy fermentation in nearly all kinds of organic matter4 ,,chapter ,,xix4 ,,composts4 ,the use of composts is an old one4 ,before artificial manures were so plentiful as they are at present1 much attention was paid by farmers to their preparation4 ,a compost is generally made by mixing some substance of animal origin which is rich in manurial ingredients with peat or loam1 and often along with lime1 alkali salts1 common salt1 and indeed any sort of refuse which may be regarded as possessing a manurial value4 ,composting1 in short1 may be looked upon as a useful method of turning to profitable use refuse of various kinds which accumulate on the farm4 ,the object of composting is to promote fermentation of the materials forming the compost1 and to convert the manurial ingredients they contain into an available condition for plant needs4 ,composts often serve a useful purpose in retaining valuable volatile manurial ingredients1 such as ammonia1 formed in easily fermentable substances like urine4 ,in fact1 we may say that farmyard manure is the typical compost1 and its manufacture serves to illustrate the principles of composting4 ,farmyard ,manure a typical ,compost4 ,farmyard manure as ordinarily made is not generally regarded as a compost1 but in the past it has been widely used for the purpose of making composts4 ,thus the practice of mixing farmyard manure with large quantities of peat has been in some parts of the world a common one4 ,peat1 as has already been pointed out in a previous chapter1 is comparatively rich in nitrogen4 ,when it is mixed with urine or some other putrescible substance1 the peat undergoes fermentation1 with the result that its nitrogen is to a greater or less extent converted into ammonia4 ,the effect1 therefore1 of mixing peat with farmyard manure is beneficial to both substances mixed3 the escape of ammonia is rendered impossible by the fixing properties of the peat1 while the inert nitrogen of the peat is largely converted by fermentation into an available form4 ,the proportion of peat which it is advisable to add in composting farmyard manure will depend on the richness of the quality of the manure3 the richer the quality of the manure1 the greater the amount of peat it will be able to ferment4 ,composts of this kind are generally made by piling up the manure in heaps1 consisting of alternate layers of peat and farmyard manure4 ,from one to five parts of peat to every one part of farmyard manure is a common proportion4 ,the use of such a manure1 containing so much organic matter1 will exercise its best effect on light sandy soils4 ,other ,composts4 ,but instead of farmyard manure1 or in addition to farmyard manure1 various other substances may be added1 as bones1 flesh1 fish-scrap1 and the offal of slaughter-houses4 ,sometimes leaves and the dried bracken-fern are used for the manufacture of composts4 ,some of these substances contain much nitrogen or phosphoric acid1 but in their natural condition ferment when applied to the soil at a slow rate4 ,if mixed together before application in pits with peat1 leaves1 bracken-fern1 or some other absorbent material1 fermentation proceeds evenly and rapidly4 ,the addition of lime1 potash1 and soda salts has been found to have a most beneficial effect in promoting fermentation4 ,these substances1 as is well known1 hasten putrefaction of organic matter4 ,lime seems especially to be valuable in composting4 ,this is no doubt due to the fact that lime plays a valuable part in promoting the action of various ferments1 as has already been illustrated in the case of nitrification4 ,the effect of large quantities of sour organic acids 7humic and ulmic71 which are the invariable products of the decomposition of organic matter like peat1 leaves1 c41 is inimical to micro-organic life4 ,the action of lime is to neutralise these acids4 ,there can be no doubt that composting is a useful process for increasing the fertilising properties of different more or less inert manurial substances4 ,but in view of the abundant supply of concentrated fertilisers1 the use of composts may considerably decrease in future4 ,,chapter ,,xx4 ,,indirect ,,manures4 ,,lime4 ,we now come to discuss those manures which we may class under the term ,indirect1 because their value is due1 not to their direct action as suppliers of plant-food--like those manures we have hitherto been engaged in discussing--but to their indirect action4 ,of these by far the most important is lime4 ,antiquity of ,lime as a ,manure4 ,lime is one of the oldest and one of the most popular of all manures4 ,it is mentioned1 and its wonderful action commented on1 in the works of several ancient writers1 more especially ,pliny4 ,of late years1 perhaps1 its use has become restricted2 and1 as we shall point out by-and-by1 it is well that it is so4 ,action of ,lime not thoroughly understood4 ,despite the fact of the long-established and almost universal use of lime1 it can scarcely be said that we as yet clearly understand the exact nature of its action4 ,much light1 however1 has been thrown of late years on the subject by the great advance which has been made in our knowledge of agricultural chemistry4 ,nevertheless1 there are many points connected with the action of lime on the soil which are still obscure4 ,perhaps one reason for the conflicting ideas prevalent with regard to the value of this substance in agriculture is to be found in the fact that it acts in such a number of different ways1 and that the nature of the changes it gives rise to in the soil is most complicated4 ,the experience of agriculturists with lime in one part of the country often seems contradictory to the experience of those in other parts of the country4 ,its action on different soils is very dissimilar4 ,for these reasons1 therefore1 the discussion of the value of lime as a manure is by no means an easy one4 ,lime a necessary ,plant-food4 ,lime1 as we have already pointed out in a former chapter1 is a necessary plant-food1 and were it present in the soil to a less extent than is actually the case1 would be just as valuable a manure as the different nitrogenous and phosphatic manures2 and in certain circumstances this is the case4 ,there are soils1 though they are by no means of common occurrence1 which actually lack sufficient lime for supporting plant-growth1 and to which its addition directly promotes the growth of the crop4 ,poor sandy soils are often of this nature4 ,another class of soils are also apt to be lacking in lime--at any rate their surface-soil is4 ,these are permanent pasture-soils4 ,originally there may have been an abundance of lime in the surface portion of the soil2 but1 as is well known to every practical farmer1 lime has a tendency to sink down in the soil4 ,this tendency in ordinary arable soils is largely counteracted by ordinary tillage operations1 such as ploughing1 c41 by means of which the lime is again brought to the surface4 ,in permanent pasture-soils1 however1 no such counteracting action takes place1 hence impoverishment of the surface-soil in lime eventually results4 ,it is for this reason--partly at any rate--that permanent pasture benefits in an especial degree by the application of lime4 ,we say partly1 for there are other important reasons4 ,one is1 that lime seems to have a striking effect in improving the quality of pastures by inducing the finer grasses to predominate4 ,it has also a very favourable action in promoting the growth of white clover4 ,another reason for the favourable effect of lime on pasture-soils is doubtless on account of the action it has in setting potash free from its compounds4 ,soils1 however1 which directly benefit from the application of lime in the same way as they benefit from the application of nitrogenous manures1 may be safely said to be rare4 ,in the great majority of soils lime exists1 so far as the demands of plant-life are concerned1 in superabundance4 ,lime of abundant ,occurrence4 ,indeed limestone is one of the most abundant of all rock substances1 and it has been calculated that it forms not less than one-sixth of the rock-mass of the earth's crust4 ,nearly all the commonly occurring minerals contain it1 and in the course of their disintegration furnish it to the soil4 ,vast tracts of country are composed of nothing but limestone2 and we have examples1 even in this country1 of so-called chalk-soils1 where it is the most abundant constituent4 ,nor can it be classed amongst the insoluble mineral constituents of the soil2 for although insoluble in pure water1 it is soluble in water--such as the soil-water--which contains carbonic acid4 ,this is proved by the fact that it is the chief dissolved mineral ingredient in all natural waters4 ,lime returned to the ,soil in ordinary ,agricultural ,practice4 ,it may be further pointed out1 as bearing upon the true function of lime when applied as a manure1 that in ordinary agricultural practice nearly all the lime removed from the soil in crops finds its way back again to the farm in the straw of the farmyard manure4 ,for these reasons1 then1 it is clear that the true function of lime is as an indirect manure4 ,let us now proceed to discuss its action4 ,before doing so1 however1 it is important that we should clearly understand the different chemical forms in which it occurs4 ,different ,forms of ,lime4 ,lime occurs chiefly as carbonate of lime in the forms of limestone1 marble1 or chalk1 which are all chemically the same4 ,it occurs also as sulphate of lime or gypsum1 as well as in the forms of phosphate and fluoride4 ,in agriculture it is only used--if we except the phosphate1 which is applied not on account of its lime1 but its phosphoric acid--in the form of the carbonate or mild lime as it is commonly called1 burnt1 caustic1 or quick lime1 and as gypsum4 ,as the value of gypsum as a manure is of such importance1 and depends not entirely on its being a compound of lime1 we shall consider it by itself4 ,hence we have only to consider here the action of mild and caustic lime4 ,caustic ,lime4 ,when limestone or mild lime is submitted to a great heat1 such as is practically done on a large scale in lime-kilns1 it is converted into caustic lime or lime proper4 ,limestone is made up1 as we have just mentioned1 of lime and carbonic acid4 ,the latter ingredient is expelled in the form of a gas1 and the lime is left behind4 ,lime never occurs naturally as caustic lime1 for the simple reason that it is impossible for it to remain in this state1 owing to the great affinity it has both for water and carbonic acid4 ,when lime is burnt1 and before it is applied to the field1 some time is allowed to elapse in order to permit of its absorbing moisture--or becoming slaked1 as it is technically called4 ,this it does more or less slowly by absorbing moisture from the air4 ,as1 however1 the process would take too long1 and as1 moreover1 the absorption of carbonic acid gas would also take place at the same time1 lime is generally slaked in another way4 ,this can be done by simply adding water4 ,an objection to this method is1 that the lime is not so uniformly slaked as is desirable4 ,it becomes gritty4 ,the usual method is to cover it up with damp earth in heaps1 and allow the moisture of the earth to effect the slaking4 ,when lime absorbs water a new chemical compound is formed1 known as lime hydrate2 and so rapidly does the lime unite with water1 that a great deal of heat is evolved in the operation1 the temperature produced being considerably above that of boiling-water4 ,the conversion of slaked lime into carbonate of lime or mild lime is a slower process4 ,sooner or later1 however1 it takes place1 whether the lime is left on the surface of the soil or buried in it4 ,a knowledge of these elementary chemical facts is necessary in order clearly to understand the nature of the action of lime in agriculture4 ,the respective action of quicklime and mild lime is1 on the whole1 similar1 although the former is in every case very much more powerful in its effects than the latter4 ,lime acts both mechanically and chemically4 ,lime may be said to act on the soil both mechanically and chemically4 ,it alters the texture of the soil1 and affects its mechanical properties1 such as its absorptive1 retentive1 and capillary powers with regard to water4 ,it acts upon its dormant fertility1 and decomposes its mineral substances as well as its organic matter4 ,lastly1 its influence on the micro-organic life of the soil1 which plays such an important part in the preparation and elaboration of plant-food1 is of the highest importance4 ,we cannot do better1 therefore1 than discuss its properties under the headings mechanical1 chemical1 and biological4 ,i4 ,,mechanical ,,functions ,,of ,,lime4 ,action on ,soil's ,texture4 ,the effect of lime upon the texture of a soil is among its most striking properties4 ,every farmer knows well what a transformation is effected in the texture of a stiff clay soil by the application of a dressing of lime4 ,the adhesive property of the soil--its objectionable tendency to puddle when mixed with water--is greatly lessened1 and the soil is rendered very much more friable when it becomes dry4 ,several reasons exist for this change4 ,in the first place1 the tendency to puddle in a clayey soil is due to the fine state of division of the soil-particles4 ,the way in which lime counteracts this adhesive property is by causing a coagulation of the fine soil-particles4 ,this flocculation or aggregation of the fine clay-particles1 when mixed with water by lime1 is strikingly demonstrated by adding to some muddy water a little lime-water4 ,the result will be that the water will speedily be rendered clear1 the fine clay-particles coming together and sinking to the bottom of the vessel4 ,even a very small quantity of lime will effect this change4 ,this property possessed by lime1 we may mention1 is utilised in the treatment of sewage4 ,as it is the fine clay-particles that are the chief cause of the puddling of clay soils1 their flocculation does much to destroy this objectionable property4 ,another reason why lime renders a clay soil more friable when dry is1 that lime does not undergo any shrinkage in dry weather4 ,as clay soils shrink very much in drying1 the mixture with such a substance as lime tends to minimise this tendency to cake in hard lumps4 ,the effect of even a very small addition of lime to a clay soil1 in the way of increasing its friable nature1 is very striking1 and can be easily illustrated by taking two portions of clay1 into one of which a small percentage of lime is introduced1 and working both into a plastic mass with water1 and then allowing them to dry4 ,it will be found that while the one is hard and resists disintegration1 that portion to which the lime has been added crumbles away easily to a powder4 ,this effect which lime has in lightening heavy soils has been known to last for years4 ,the disintegrating effect of quicklime when applied to heavy soils is also due1 it may be added1 to the change undergone by the lime itself from the caustic state to the mild state4 ,lime renders light ,soils more cohesive4 ,although it may seem somewhat paradoxical1 lime1 it would appear1 in some cases exercises an effect upon the soil exactly the reverse of what has just been stated4 ,that lime should act as a binding agent is only natural when we reflect on the way in which it acts when used as mortar4 ,it is quite to be understood1 therefore1 that its action on light friable soils should be to increase their cohesive powers1 and at the same time to increase the capillary power of the soil to absorb water from the lower layers4 ,the extent of this action1 of course1 would depend on the form in which the lime is applied1 and the amount4 ,a striking example of the binding power of lime is to be found in certain soils extremely rich in lime1 in which what is known as a lime-pan has been formed at some distance from the surface4 ,,ii4 ,,chemical ,,action ,,of ,,lime4 ,but more important probably than even its mechanical action is the chemical action of lime4 ,it is a most important agent in unlocking the inert fertility of the soil4 ,this it does by decomposing different minerals and setting free the potash they contain4 ,the disintegrating power of lime in this respect depends1 of course1 on its chemical condition1 the caustic form being much more potent than the other forms4 ,its action in decomposing vegetable matter and rendering the inert nitrogen it contains available for the plant's use1 is also one of its most important properties1 and accounts for its beneficial action when applied to soils1 such as peaty soils1 rich in organic matter4 ,again1 its use as a corrective for sour lands has long been practically recognised4 ,the presence of acidity in a soil is hurtful to vegetable life4 ,lime1 by neutralising this acidity1 removes the sourness of the land1 and does much to restore it to a condition suitable for the growth of cultivated crops4 ,the generation of sourness in a soil is almost sure to give rise to certain poisonous compounds4 ,lime1 therefore1 in sweetening a soil1 prevents the formation of these poisonous compounds4 ,badly drained and sour meadow-lands1 as every farmer knows1 are immensely benefited by the application of this useful manure2 for not merely is their sourness removed and their general condition ameliorated1 but many of the coarser and lower forms of plant-life1 which alone flourish on such soils1 are killed out1 and the more nutritive grasses are allowed to flourish instead4 ,the action of lime in promoting the formation of a class of compounds of great importance in the soil--viz41 hydrated silicates--is worthy of notice4 ,according to the commonly accepted theory1 much of the available mineral fertilising matter of the soil is retained in the form of these hydrated silicates4 ,hence lime1 by increasing these compounds1 not merely adds to the amount of the available fertility in the soil1 but also increases its absorptive power for food-constituents4 ,,iii4 ,,biological ,,action ,,of ,,lime4 ,the last way in which lime acts is what we have termed biological4 ,by this we mean the important role lime plays in promoting or retarding1 as the case may be1 the various kinds of fermentative action which go on so abundantly in all soils4 ,the presence of carbonate of lime in the soil is a necessary condition for the process of nitrification4 ,lime is the base with which the nitric acid1 when it is formed1 combines2 and as we have seen1 when discussing nitrification1 soils of a chalky nature are among those best suited to promote the natural formation of nitrates4 ,this is one of the reasons for the beneficial effects produced by lime when applied to peaty soils4 ,not merely does it help to decompose the organic matter so abundant in such soils1 but it also furnishes the base with which the nitric acid may combine when it is formed4 ,but while the action of lime is to promote fermentation1 it must not be forgotten that there may be cases in which its action is rather the reverse of this4 ,fermentation of organic matter goes on when there is a certain amount of alkalinity present2 while1 on the other hand1 the presence of acidity seems to retard and check it4 ,too great an amount of alkalinity1 however1 would1 in the first instance1 retard fermentation as much as too great acidity4 ,it has been claimed that the addition of caustic lime to fresh urine may act in this way2 and if this were so1 the addition of lime to farmyard manure might1 to a certain extent1 be defended4 ,the experiment1 however1 would be a hazardous one and not to be recommended1 as loss of ammonia would most likely ensue4 ,action of ,lime on ,nitrogenous ,organic ,matter4 ,the action of lime on nitrogenous organic matter is of a very striking kind1 and is by no means very clearly understood4 ,as we have pointed out1 it sometimes acts as an antiseptic or preservative2 and this antiseptic or preservative action has been explained on the assumption that insoluble albuminates of lime are formed4 ,its action in such industries as calico-printing1 where it has been used along with casein for fixing colouring matter2 or in sugar-refining1 where it is used for clarifying the sugar by precipitating the albuminous matter in solution in the saccharine liquor2 or lastly1 in purifying sewage1--has been cited in support of this theory4 ,while1 however1 there may be circumstances in which lime1 especially in its caustic form1 acts as an antiseptic1 its general tendency is to promote these fermentative changes1 such as nitrification1 so important to plant-life4 ,an important use of lime in agriculture is in preventing the action of certain fungoid diseases1 such as rust1 smut1 finger-and-toe1 c41 as well as in killing1 as every horticulturist and farmer knows1 slugs1 c4 ,recapitulation4 ,we may1 in conclusion1 sum up in a single paragraph the different ways in which lime acts4 ,its action is mechanical1 chemical1 and biological4 ,it acts on the texture of the soil1 rendering clay soils more friable1 and exerting a certain binding effect on loose soils4 ,it decomposes the minerals containing potash and other food-constituents1 and renders them available for the plant's needs4 ,it further decomposes organic matter1 and promotes the important process of nitrification4 ,it increases the power of a soil to fix such valuable food-constituents as ammonia and potash4 ,it neutralises sourness1 and prevents the formation of poisonous compounds in the soil4 ,it increases the capillary condition of the soil1 prevents fungoid diseases1 and promotes the growth of the more nutritive herbage in pasture-land4 ,,chapter ,,xxi4 ,,indirect ,,manures--,,gypsum1 ,,salt1 ,,etc4 ,,gypsum4 ,in the previous chapter mention was made of gypsum as a compound of lime1 but no reference to its action as a manure was made4 ,in the past1 gypsum was used extensively and highly valued4 ,it was found to be of especial value for clover2 and there is a story told of ,benjamin ,franklin which illustrates the very striking nature of its action on this crop4 ,it is related that he once printed with gypsum the words ,this has been plastered on a field of clover1 and that for a long time afterwards the legend was plainly discernible on account of the luxuriance of the clover on the parts of the field which had been thus treated4 ,mode in which gypsum acts4 ,despite the fact that gypsum is a most ancient manure1 it is only of late years that we have come to understand the true nature of its action4 ,for long it was believed that the reason of its striking effect in promoting clover was due to the fact that1 as clover was a lime-loving plant1 the action of gypsum was owing to the lime it contained4 ,that1 however1 the action of gypsum is not due to the fact that it supplies lime to the plant1 seems evident when it is stated that were this so1 any other form of lime would have the same beneficial effect4 ,it is well known1 however1 that this is not so4 ,besides1 as we have already pointed out1 lime is not a constituent which most soils lack1 so far as the needs of the crop are concerned4 ,there is a certain amount of truth in the old belief that gypsum enriches the soil in ammonia by fixing it from the air4 ,the power that gypsum has as a fixer of ammonia has already been referred to in the chapter on ,farmyard ,manure2 but in this case the gypsum is brought in contact with the ammonia4 ,the origin of this old belief was due to a misconception as to the amount of ammonia in the atmosphere4 ,no doubt gypsum greatly increases the power of a soil to absorb ammonia from the air2 but the quantity of ammonia in the air is so very trifling1 that its action in this respect is hardly worth considering4 ,the true explanation of the action of gypsum is to be found in its effect on the double silicates1 which it decomposes1 the potash being set free4 ,its action is similar to that of other lime compounds1 only more characteristic4 ,as a manure1 therefore1 its action is indirect1 and its true function is to oust the potash from its compounds4 ,its peculiarly favourable action on clover is due to the fact that clover specially benefits by potash1 and that adding gypsum practically amounts to adding potash4 ,of course it should be borne in mind that the soil must contain potash compounds if gypsum is to have its full effect4 ,now1 however1 that potash salts suitable for manuring purposes are abundant1 it may well be doubted whether it is not better to apply potash directly4 ,further1 it must be borne in mind that gypsum is applied to the soil whenever it receives a dressing of superphosphate of lime1 as gypsum is one of the products formed by treating insoluble phosphate of lime with sulphuric acid4 ,it is possible that gypsum may act as an oxidising agent in the soil1 just as iron in the ferric condition does4 ,it has a large quantity of oxygen in its composition1 and under certain conditions may act as a carrier of oxygen to the lower layers of the soil4 ,when it is used1 it should be applied some months before the crop is sown4 ,gypsum1 therefore1 although it contains two necessary plant-constituents1 lime and sulphuric acid1 cannot be regarded as a direct manure2 and as its action comes to be more fully understood1 its use1 which was never very abundant in this country1 will probably decrease4 ,we have already1 in the chapter on ,nitrification1 referred to the action of gypsum in promoting nitrification4 ,,salt4 ,the action of salt as a manure presents a problem which is at once of the highest interest and surrounded with the greatest difficulties4 ,in view of the large quantities now used for agricultural purposes1 a somewhat detailed examination of the nature of its action is not out of place in a work such as the present4 ,antiquity of the ,use of ,salt4 ,the recognition of the manurial functions of salt dates back to the very earliest times4 ,its use among the ancients is testified by numerous allusions in the ,old ,testament2 while1 according to ,pliny1 it was a well-known manure in ,italy4 ,the ,persians and the ,chinese seem also to have used it from time immemorial1 the former more especially for date-trees4 ,nature of its ,action4 ,despite1 however1 the great antiquity of its use1 much difference of opinion seems always to have existed as to the exact method of its action1 and as to its merits as a manure in promoting vegetable growth4 ,it furnishes1 in fact1 a good example of the difficulty which exists in the case of many manures1 whose action is chiefly indirect1 of fully understanding their influence on the soil and on the crop4 ,in fact1 the action of salt is probably more complicated than that of any other manurial substance4 ,salt not a necessary ,plant-food4 ,we have already seen that neither sodium nor chlorine--the two constituent elements of salt--are in all probability absolutely necessary plant-foods4 ,if they are necessary1 the plant only requires them in minute quantities4 ,despite this fact1 soda is an ash-constituent of nearly every plant1 and in many cases one of the most abundant4 ,in amount it is one of the most variable of all the ash-constituents1 being present in some plants only in minute quantities1 while in others it occurs in large quantities4 ,mangel and plants of the cabbage tribe may be cited as examples of plants containing large amounts of soda in their composition4 ,but the plants which contain it in largest quantity are those which thrive on the sea-coast1 and it has been thought that for them at least salt is a necessary manure4 ,this1 however1 does not seem to be the case4 ,in fact1 the amount of soda in a plant seems to be largely a matter of accident4 ,it may be added that the succulent portions of a plant are generally richest in soda4 ,can ,soda replace ,potash8 ,again1 it has been believed that soda is capable of replacing potash in the plant2 but this does not seem to be the case to any extent4 ,the view that soda is able to replace potash1 it has been thought1 is supported by the variation which exists in the proportion of soda and potash in different plants4 ,it must be remembered1 however1 that it is highly probable that most plants contain a larger quantity of ash-constituents than is absolutely necessary for their healthy growth4 ,especially is this the case with such a necessary plant-food as potash1 of which there is generally present1 in all likelihood1 an excess4 ,the variation in the quantity of potash and soda present in many plants under different circumstances can scarcely1 therefore1 be regarded as furnishing a proof of the replacement of potash by soda4 ,incidentally we may mention1 as a fact worthy of notice1 that cultivated plants have more potash and less soda in their composition than wild plants4 ,what has been said of soda may be held to apply equally to chlorine1 as it seems to be chiefly in the form of common salt that soda enters the plant4 ,the amount of salt1 therefore1 present in plants must be regarded as largely accidental and dependent on external circumstances1 such as the nature of the soil1 c4 ,salt of universal ,occurrence4 ,but even were salt a necessary plant-food1 its occurrence in the soil is already of sufficient abundance to obviate any necessity for its application4 ,it may be said to be of almost universal occurrence4 ,even the air contains it in traces4 ,that this is the case in the neighbourhood of the sea-coast is well known2 but even in air far inland1 accurate analysis of the air would probably demonstrate its presence in greater quantity than is commonly believed4 ,it is a wise provision that plants absorb salt1 for it increases their efficiency as food1--the function of salt as a constituent of animal food being of the very highest importance4 ,it is an indispensable food-ingredient for animal life4 ,with regard to ordinary farm-stock1 the amount of salt which naturally occurs in their food is quite sufficient4 ,in the case1 however1 of pastures in countries far removed from the sea1 the custom of specially supplying stock with salt is common4 ,this is done by placing a piece of rock-salt in the fields4 ,special ,sources of ,salt4 ,the salt of commerce is obtained from various sources4 ,besides the sea1 we have ample sources of salt in the large saline deposits found in many parts of ,europe1 especially in ,austria1 and in ,england in ,cheshire4 ,the ,action of ,salt indirect4 ,from what has been said above1 it is clear that the action of salt as a manure is indirect and not direct4 ,what the nature of that indirect action is we shall now proceed to discuss4 ,in considering the evidence of the manurial value of salt1 we are at once brought face to face with the fact that the experience of its action in the past has as often been unfavourable as favourable4 ,salt1 it is well known1 is both an antiseptic and a germicide4 ,it is1 indeed1 one of the most commonly used of preservatives4 ,when applied in large quantities to the soil1 it has a most deleterious action on vegetation4 ,this hurtful action of salt has long been known2 and it is as often mentioned in the writings of antiquity on account of its unfavourable as on account of its favourable action4 ,thus1 for example1 among the ancient ,jews it was customary1 after the conquest of a hostile town1 to strew salt on the enemy's fields1 for the purpose of rendering them barren and unfertile4 ,and again1 among the ,romans1 for the same purpose1 salt was often spread on a spot where some great crime had been committed4 ,while1 therefore1 its unfavourable action has long been known1 the fact that there are circumstances under which its action is1 on the contrary1 favourable for promoting vegetable growth has also been long recognised4 ,the difficulty for the agricultural student is to reconcile these two seemingly contradictory experiences4 ,for the ,english agriculturist the subject possesses especial interest1 since in ,england it has been in the past most generally used and its action most discussed since the time of ,lord ,bacon1 who discusses in his writings the action of solutions of it on different plants4 ,the true explanation of salt being so different in its action is to be found in the quantity applied1 the nature of the soil1 the crop to which it is applied1 and the conditions under which it is applied--i4e41 whether it is applied alone or along with other manures4 ,mechanical ,action on ,soils4 ,in the first place1 it must be noted that salt exerts a mechanical action on the soil of a very similar kind to that exercised by lime4 ,when applied to clay soils it causes a flocculation or coagulation of the fine clay-particles1 and thus prevents the soil from puddling to the same extent as would otherwise be the case4 ,in fact1 an example of this action of salt when in solution causing the precipitation of fine suspended clayey matter1 is afforded by the formation of deltas at the mouths of rivers4 ,the power of clarifying muddy water is common indeed to saline solutions4 ,schloesing attributes the clarifying power of a soil to the presence of the saline matters it contains2 and from this point of view it would appear that manures containing any saline substance may exert an important mechanical influence on the soil4 ,solvent ,action4 ,but a much more important property of salt is its solvent action on the plant-food present in the soil4 ,its action in decomposing the minerals containing lime1 magnesia1 potash1 c41 is similar to the action of gypsum4 ,by acting upon the double silicates it liberates these necessary plant-foods4 ,it is not only on the basic substances upon which it acts1 but also on the phosphoric and silicic acids1 which it sets free4 ,its power of dissolving ammonia from the soil is considerable4 ,experiments with a weak solution of salt on a soil by ,peters and ,eichhorn to test its solvent power1 showed that the salt solution dissolved more than twice as much potash and nearly thirty times as much ammonia as an equal quantity of pure water did4 ,when applied to the soil1 it seems chiefly to liberate lime and magnesia4 ,the exact nature of the chemical action taking place is a point of some dubiety4 ,according to some1 it is changed into nitrate of soda2 according to others1 into carbonate of soda4 ,the latter theory seems to be the more probable one4 ,its action on the lime and magnesia compounds is to convert them into chlorides2 and this chemical reaction explains the action that salt has in increasing the water-retaining and water-absorbing power of the soil2 for the chlorides of magnesia and lime are salts which have a great power of attracting water from the air4 ,again1 the very fact that salt acts as an antiseptic may serve to explain its beneficial action in certain cases where it prevents rankness of growth4 ,no doubt this was its function when applied along with ,peruvian guano4 ,this it might do by preventing too rapid fermentation 7nitrification7 of the manure1 or by actually weakening the plant4 ,its action when applied with farmyard manure may also be similar4 ,but while its effect in many cases may be towards retarding fermentation1 on the other hand its action1 when applied along with lime to compost-heaps1 is towards promoting more rapid decomposition4 ,probably a reaction takes place between the lime and the salt1 the result of which is the formation of caustic soda4 ,such are some of the ways in which salt may act4 ,it must at once be seen how its action in one case will be favourable and in another case unfavourable4 ,there must be fertilising matter present in the soil if it is to act favourably4 ,again1 it will only be under such circumstances1 where rankness of growth is likely to ensue1 that its antiseptic properties will act favourably and not unfavourably4 ,best used in small ,quantities along with ,manures4 ,probably it is for these reasons that its action has been found to be most favourable when applied along with other manures and not alone4 ,applied along with nitrate of soda1 as is commonly done1 it doubtless increases the efficiency of the nitrate4 ,some plants seem to be undoubtedly benefited by salt3 of these flax may be mentioned4 ,the application of salt to plants of the cabbage tribe seems also to be highly beneficial4 ,on mangels1 along with other manures1 it has also been found to have a very favourable effect4 ,but with many crops its action has been proved to be less favourable4 ,affects ,quality of ,crop4 ,although salt has often been found to increase the quantity of a crop1 the quality of the crop has been made to suffer4 ,its action on beetroot has been more especially studied4 ,the effect of its application is to lessen the total quantity of dry matter and sugar in the plant4 ,this has been found to be the case both when the salt was applied alone and along with nitrate of soda and other manures4 ,on potatoes1 again1 its action has been found to be deleterious1 lessening their percentage of starch4 ,the deleterious action of chlorides on the quality of potatoes is also seen when potassium chloride is applied4 ,it is for this reason that potash should never be applied to the potato crop in the form of chloride4 ,in the late ,dr ,voelcker's opinion1 the conditions under which salt had the most favourable action on the mangel crop was in the case of a light sandy soil1 and applied at the rate of #d to #e cwt4 per acre4 ,its action when applied to clay soils was not so favourable4 ,rate of ,application4 ,lastly1 the rate at which it may be applied will naturally vary4 ,from #a cwt4 and even less1 up to #f cwt4 or even more1 has been the rate at which it has been commonly applied in the past4 ,from what has been said1 it will be seen that it is more likely to exert a favourable influence when applied only in small quantities4 ,,chapter ,,xxii4 ,,the ,,application ,,of ,,manures4 ,the conditions which regulate the application of manures are many and varied1 and the subject1 it must be admitted1 despite the large amount of investigation already carried out1 is most imperfectly understood4 ,for these reasons it is impossible to do little more than lay down certain general principles which may be of service to the agriculturist in guiding him in carrying out the manuring of his crops4 ,influence of ,manures in increasing ,soil-fertility4 ,in the first place it may be asked1 ,how far can what we may call the permanent fertility of a field be influenced by the application of manures8 ,and to this question the answer must be made1 that the influence of manuring in increasing soil-fertility is very slight and only very gradually felt4 ,this is illustrated by the difficulty experienced in attempting to restore to a fertile condition a soil which has long been treated by an exhaustive system of cultivation4 ,in such a case it will be found impossible to restore the fertility of the soil1 except very gradually4 ,farmers who farm in new countries1 and in rich virgin soils1 little realise sometimes how quickly they may impoverish the fertility of their soils by exhaustive treatment1 and how slow the process of restoration is4 ,nor is this strange when we reflect on the relatively small quantities of fertilising ingredients we are in the habit of adding to the soil by the application of manures1 and the nature of their action4 ,the small rate at which they are applied1 and the impossibility of distributing them equally in the soil1 explain how comparatively limited their action must necessarily be4 ,some manures1 it is true--viz41 those which are soluble--are more equally distributed2 but then such manures1 from their very nature1 are little likely to affect the permanent fertility of the soil4 ,influence of ,farmyard ,manure on the ,soil4 ,of manures which have the best effect in improving a soil's permanent fertility1 farmyard manure is undoubtedly the most important4 ,this is owing partly to the fact that it is applied in such large quantities1 and partly on account of its composition4 ,liberal manuring with farmyard manure1 systematically carried out1 will in time do much to build up a soil's fertility4 ,but liberal manuring with artificial manures will also effect the same end4 ,this it does in an indirect manner by means of the increased crop residues obtained under such treatment4 ,indeed one of the speediest methods of bringing a soil into good condition is by heavily manuring certain green crops1 and then ploughing them in4 ,farmyard ,manure v4 ,artificials4 ,the question how far farmyard manure may be supplanted by artificials is one often discussed4 ,we have already referred to this question in the chapter on ,farmyard ,manure4 ,it is possible that1 with our increasing knowledge of agricultural science1 we may in the future be able to dispense with farmyard manure1 and make shift to do with artificials alone4 ,at present1 however1 all our experience points to the fact that the most satisfactory results are obtained from manures by using artificials in conjunction with farmyard manure4 ,it is better both for farmyard manure and artificial manures to be applied together1#bda so that they may mutually act as supplementary the one to the other4 ,while this is so1 there may be circumstances in which it will be best to use artificials alone4 ,where1 for example1 fields1 owing to their situation1 are inaccessible1 and where the expense of conveying the bulky farmyard manure would be very considerable1 it may be found more economical to apply the more concentrated artificial manures4 ,with few exceptions1 however1 it will be found most desirable to use artificial manures as supplementary to farmyard manure1 and not as substitutes for it4 ,farmyard ,manure not favourable to certain ,crops4 ,while the above is true1 it may be well to point out one or two facts regarding the nature of the influence of farmyard manure on certain crops4 ,for instance1 it has long been recognised as inadvisable in strong rich soils to apply it directly to certain grain crops1 such as barley and wheat1 since such a practice is apt to encourage rankness of growth--an undue development of straw at the expense of the grain4 ,it is consequently customary to apply farmyard manure to the preceding crop4 ,the direct application of farmyard manure to wheat1 however1 according to ,sir ,j4 ,b4 ,lawes1 is not fraught with unfavourable results where the soil is a light one2 it is only when the soil is of a heavy nature that it is best to apply it to the preceding crop4 ,potatoes are another crop to which it is best not to apply it directly4 ,on the other hand1 many are of the opinion that mangels seem to be able to benefit from large applications of farmyard manure4 ,conditions determining the ,application of ,artificial ,manures4 ,in the application of artificial manures a large number of considerations have to be taken into account4 ,among these may be mentioned the nature of the manure itself1 and its mechanical and chemical condition2 the nature of the soil and its previous treatment with manures1 as well as the nature of the climate1 the nature of the crop1 and the previous cropping4 ,it may be well1 therefore1 to examine somewhat in detail some of these considerations4 ,nature of the ,manure4 ,nitrogen1 phosphoric acid1 and potash exist in the common manures1 as has already been pointed out1 in different states of availability4 ,nitrogen1 for example1 may exist in a soluble or insoluble condition1 as nitrates1 as ammonia1 or in various organic forms4 ,phosphoric acid1 similarly1 may exist in a soluble form1 as it does in superphosphate of lime1 or in an insoluble form1 as it does in bones or basic slag4 ,potash1 on the other hand1 exists--or should exist--in artificial manures only in a soluble form4 ,now a correct knowledge of the behaviour of these different forms of the common manurial ingredients when applied to the soil is1 in the first place1 necessary for their successful and economical use4 ,nitrogenous ,manures4 ,thus our knowledge of the inability of the soil-particles to retain nitrogen in the form of nitric acid1 as well as our knowledge of the fact that nitrogen is in this form immediately available for the plant's needs1 teaches us that nitrate of soda should never be applied before the plant is ready to utilise it--in short1 that it should only be applied as a top-dressing2 and further1 that the use of such a fertiliser in a damp season is less likely to be economical than in a dry one4 ,again1 with regard to nitrogen in the form of ammonia salts1 our knowledge of the fact that ammonia is retained by the soil-particles1 and that before it becomes available for the plant's needs it has to undergo the process of nitrification1 teaches us the desirability of applying it a short time before it is likely to be used4 ,while1 lastly1 with regard to the nitrogen in the various organic forms in which it occurs1 our knowledge of the rate at which these are converted into an available form in the soil will determine when they are best applied4 ,some forms of organic nitrogen are in a soluble condition1 and are quite as speedy in their action as sulphate of ammonia4 ,this is the case with a considerable proportion of the different organic forms of nitrogen present in guano4 ,other forms of organic nitrogen are only slightly less so--as1 for example1 dried blood1 which ferments very speedily4 ,with regard1 therefore1 to nitrates and ammonia salts1 as well as the more quickly available organic forms of nitrogen1 they should either be applied as a top-dressing after the plant has started growth1 or only shortly before seed-time4 ,bones1 shoddy1 and the various so-called native guanos1 should be applied a considerable period before they are likely to be required--not later than the previous autumn4 ,phosphatic ,manures4 ,with regard to phosphatic manures the same considerations hold good4 ,inasmuch as phosphoric acid1 whether applied in the soluble condition1 as in superphosphate1 or the insoluble form1 as in bones1 basic slag1 c41 is not liable to be washed out of the soil1 the risk of loss is very slight1 and need not be taken into account4 ,as we have pointed out in considering the action of superphosphate1 phosphoric acid in this latter form is more speedily available to the crop1 and the necessity of applying it much before it is likely to be used does not exist4 ,hence superphosphate and manures which contain any appreciable amount of soluble phosphoric acid1 such as guano1 should only be applied shortly before seed-time4 ,bones1 basic slag1 or mineral phosphate ought to be applied1 on the other hand1 a long time before they are likely to be used4 ,hence an autumn application is to be recommended in the case of such manures4 ,potash ,manures4 ,lastly1 with regard to potash manures1 as these are soluble1 there is no necessity for applying them much before they are likely to be absorbed by the plant4 ,some are of the opinion that potash is1 except in the case of sandy soils1 best applied some little time before it is likely to be used1 so as to permit of its being washed down into the soil--a process which takes place only comparatively slowly4 ,as potash manures have often been found to give a better result on pastures during the second year than during the first1 they are best applied in the autumn4 ,the above statement as to the behaviour of the different fertilisers when applied to the soil1 has a not unimportant bearing on the quantities in which they may safely be respectively applied4 ,the rate at which manures may be applied depends1 as we shall immediately see1 on other conditions2 but what it is here desirable to point out is1 that it is not safe to apply such manures as nitrate of soda1 or1 for that matter1 sulphate of ammonia1 in large quantities at a time4 ,in fact these manures1 especially the former1 will best be applied in very small quantities1 and rather in several doses4 ,with regard to other manures1 more especially phosphatic manures1 the same reasons for small application do not exist4 ,the truth of the above statements is so obvious that it may be regarded as superfluous to make them4 ,as1 however1 their clear apprehension is essential to understanding the conditions of successful manuring1 no apology need be made for making them4 ,nature of ,soil4 ,another condition which has to be taken into account in considering the application of manures is the nature of the soil1 as well as its previous treatment4 ,soils poor in organic matter are those which are most likely to be benefited by the application of nitrogenous manures4 ,soils of a dry light character require less phosphoric acid than they do of nitrogen and potash2 while on a damp and heavy soil phosphatic manures are more likely to be beneficial than nitrogenous or potassic manures4 ,lastly1 a soil rich in organic matter generally requires phosphates1 and possibly potash4 ,a point of considerable importance to notice is1 that a soil rich in lime can stand a larger application of phosphoric acid than one poor in lime4 ,as a rule1 it will be found that the best results with potash will be obtained when applied to a sandy soil4 ,the nature of the soil is an important consideration in determining how far it is advisable to apply readily soluble manures4 ,to a very light and non-retentive soil the risk of loss in applying an easily soluble manure is considerably increased4 ,the nature of the climate is also of importance4 ,thus1 in a dry climate1 manures of a soluble nature will have a better effect than in a wet climate1 while the opposite will be the case with the more slowly acting manures4 ,nature of previous ,manuring4 ,a consideration of equal importance is the previous treatment of the soil with manure4 ,for example1 where a soil has been liberally treated with farmyard manure1 it has been found that mineral manures have a very inferior effect to that obtained by nitrogenous manure4 ,lawes and ,gilbert have found this to be strikingly the case in their experiments on the growth of wheat4 ,in these experiments it was found that the application of mineral manures was accompanied with little or no benefit to the crop1 whereas very striking results followed the application of nitrogen4 ,this they attributed to the fact that the supply of mineral fertilisers in the straw of the farmyard manure is largely in excess of the supply of nitrogen4 ,the nature of the action of the manure previously applied is also to be taken into account in determining how long its influence may probably last4 ,where1 for example1 the manure has been nitrate of soda or sulphate of ammonia1 it may be safely concluded that its direct influence is no longer felt a year after application4 ,the influence of superphosphate of lime1 while scarcely so temporary1 may be said to last only for a comparatively short time4#bdb ,on the other hand1 when the manure applied is of a slow-acting nature1 such as bones or basic slag1 its influence will probably be felt for a number of years4 ,nature of the ,crop4 ,but more important than any of the above-mentioned conditions is the nature of the crop itself4 ,our knowledge of the requirements of the different farm crops is still very imperfect4 ,a very wide experience1 however1 of the effect of different manures on different crops1 has conclusively proved that their manurial requirements differ very considerably4 ,the subject is complicated by other considerations1 such as the nature of the soil1 c42 but notwithstanding this fact1 certain points seem to be pretty well established4 ,in seeking to understand the respective requirements of the different crops for different fertilisers1 two important considerations must be borne in mind4 ,these are--7#a7 the quantities of the three fertilising ingredients--nitrogen1 phosphoric acid1 and potash--which different crops remove from the soil2 and 7#b7 the different power crops possess of assimilating these ingredients4 ,amounts of ,fertilising ,ingredients removed from the ,soil by different ,crops4 ,the most convenient way of instituting a comparison between the requirements of the different crops in this respect is by calculating the amount1 in pounds1 of nitrogen1 phosphoric acid1 and potash1 which average amounts of the different crops remove per acre4 ,the following table shows this for the common crops3-- ,,fertilising ,,ingredients ,,removed ,,from ,,soil4 ---------------------------------------- --------------------- ,nitrogen4 ,phosphoric ,potash4 ,acid4 ---------------------------------------- --------------------- ,mangels ,root1 #bb tons #hg #cf4d #bbb4h ,leaf #ea #af4e #gg4i --------------------------------- ,total crop #ach #eb4i #cjj4g --------------------------------- ,turnips ,root1 #ag tons #fc #bb4d #ajh4f ,leaf #di #aj4g #dj4b --------------------------------- ,total crop #aab #cc4a #adh4h --------------------------------- ,beans ,grain1 #cj bushels #gg #bb4h #bd4c ,straw #bi #f4c #db4h --------------------------------- ,total crop #ajf #bi4a #fg4a --------------------------------- ,red clover hay1 #b tons #ajb #bd4i #hc4d --------------------------------- ,swedes ,root1 #ad tons #gj #af4i #fc4c ,leaf #bh #d4h #af4d --------------------------------- ,total crop #ih #ba4g #gi4g --------------------------------- ,oats ,grain1 #de bushels #ch #ac4j #i4a ,straw #ag #f4d #cg4j --------------------------------- ,total crop #ee #ai4d #df4a --------------------------------- ,meadow hay1 #a-a_/b ton1 #di #ab4c #ej4i --------------------------------- ,wheat ,grain1 #cj bushels #cc #af4j #i4h ,straw #ae #d4g #be4i --------------------------------- ,total crop #dh #bj4g #ce4g --------------------------------- ,barley ,grain1 #cj bushels #ce #af4j #i4h ,straw #ac #d4g #be4i --------------------------------- ,total crop #dh #bj4g #ce4g --------------------------------- ,potatoes1 #f tons #dg #ba4e #gf4e --------------------------------- ,maize ,grain1 #cj bushels #bh #aj4j #f4e ,stalks1 c4 #ae #h4j #bi4h --------------------------------- ,total crop #dc #ah4j #cf4c ---------------------------------------- --------------------- ,from the table it will be seen that the crops which remove the largest quantities of all three fertilising ingredients are the root crops--mangels and turnips2 that beans remove twice as much nitrogen as the cereals--oats1 barley1 and wheat--which1 in this respect1 practically differ very little from one another2 while potatoes remove about the same quantity of nitrogen as the cereals4 ,it will further be noticed that the amounts of phosphoric acid removed by the different crops differ very much less than those of nitrogen and potash4 ,mangels remove slightly more1 and turnips slightly less1 than double the amount removed by cereals4 ,meadow-hay1 it will be seen1 of all crops removes the least phosphoric acid4 ,in looking at the amounts of potash1 we are at once struck by their great discrepancy4 ,such a crop as mangels removes more than six times as much potash from the soil as the cereals4 ,turnips also make large demands on this ingredient1 removing over four times as much as the cereals4 ,leguminous crops1 such as red clover and beans1 remove about twice as much4 ,capacity of ,crops for assimilating ,manures4 ,instructive though these figures undoubtedly are1 they must not be regarded1 as often erroneously they are1 as furnishing by themselves sufficient data upon which to base the practice of manuring4 ,a consideration which is of much greater importance is the capacity that different crops possess for assimilating the various manurial ingredients from the soil4 ,considered from the point of view of absolute amount1 there is in most soils an abundant supply of plant-food2 but of this amount only a small proportion is available4 ,further1 the amount of this available plant-food will vary with different crops--one crop being able to grow where another crop would starve4 ,as illustrative of this1 in the ,norfolk experiments it was found that the turnip was able to assimilate potash from a soil on which the swede was practically starved4 ,it is on this fact more than any other that the principles of manuring are based4 ,several explanations of the different capacities crops possess of assimilating their food may be put forward4 ,and we may here point out that crops belonging to the same class exhibit1 on the whole1 a certain amount of similarity in their manurial requirements4 ,thus1 for example1 we may say that gramineous crops so far resemble one another in possessing small capacity for assimilating nitrogen1 root crops for assimilating phosphoric acid1 and leguminous crops for assimilating potash1 and that1 consequently1 these crops are generally most benefited by the application1 respectively1 of nitrogen1 phosphoric acid1 and potash4 ,but while a certain general resemblance exists1 crops belonging to the same class differ in many cases very considerably1 as we shall immediately see4 ,difference in ,root ,systems of different ,crops4 ,one explanation of the different capacity possessed by different crops for absorbing plant-food from the soil is to be found in the difference of their root systems4 ,every agriculturist knows that crops in this respect differ very widely4 ,crops having deep roots will naturally have a larger surface of soil from which to draw their food-supplies than crops having shallower roots4 ,such crops as red clover1 wheat1 and mangels are able to draw their food-supplies from the subsoil to an extent not possessed by shallower-rooted crops1 such as barley1 turnips1 and grass4 ,crops having surface-roots1 on the other hand1 have often greater capacity for assimilating nitrogen1--this ingredient1 as has already been pointed out1 being chiefly located in the surface-soil4 ,the tendency of growing shallow-rooted crops will therefore be towards impoverishing the surface-soil2 whereas the occasional growth of a deep-rooted crop brings the plant-food in the subsoil into requisition4 ,in this connection it may be well to draw attention to the singular capacity possessed by certain crops for absorbing nitrogen4 ,of these the case of clover is the most striking1 and has long puzzled agriculturists4 ,the discovery1 which has been repeatedly referred to in these pages1 that the leguminous order of crops1 to which clover belongs1 have the power of absorbing the free nitrogen of the air through the agency of micro-organic life in the plant and in the soil1 has furnished an explanation of this long-debated problem4 ,period of ,growth4 ,a further reason is the difference in the period of a crop's growth4 ,a crop which grows quickly1 and consequently occupies the ground during a comparatively short period1 will naturally require a richer soil1 and therefore a more liberal treatment with manure1 than one whose growth is more gradual4 ,another consideration is the season of the year during which active growth of the crops takes place4 ,for example1 in the case of the wheat crop1 active growth takes place in spring and ceases early in the summer4 ,since1 however1 nitrification goes on right through the summer1 and nitrates are most abundant in the soil in late summer and autumn1 such a crop as wheat is ill suited to obtain any benefit from this bountiful provision of nature1 and is consequently particularly benefited by the application of nitrogenous manures4 ,root crops1 on the other hand1 sown in summer1 continue their active growth into autumn1 and are thus enabled to utilise the nitrates formed in the process of nitrification4 ,the custom of sowing a quickly growing green crop1 such as rye1 mustard1 rape1 c41 after a wheat crop1 is a practice which aims at conserving the nitrates and preventing their loss by autumn and winter rains4 ,the name catch crop has been applied to such a crop4 ,by ploughing under the green crop1 the nitrogen removed from the soil in the form of easily soluble nitrates is restored in an insoluble organic form1 and the soil is at the same time enriched by the addition of much valuable organic matter4#bdc ,it is chiefly the above facts that form the scientific basis of the long-pursued practice of the rotation of crops4 ,variation in ,composition of ,crops4 ,a point of considerable interest is the influence exerted by manures on the composition of crops4 ,it has been assumed in the preceding pages that the composition of crops of the same plant is uniform2 but this is not strictly the case1 as it has been proved that not merely the manure and soil have an appreciable influence on the crop's composition1 but so also has the climate4 ,absorption of ,plant-food4 ,the laws regulating the absorption of plant-food are most interesting1 although1 unfortunately1 very imperfectly understood as yet4 ,the fertilising ingredients are capable of considerable movement in the plant1 and are only absorbed up to a certain period of growth4 ,this in many plants is reached when they flower4 ,after this period they are no longer capable of absorbing any more food4 ,the popular belief that plants in ripening exhaust the soil of its fertilising matters is consequently a fallacy4 ,fertilising ,ingredients lodge in the ,seed4 ,the tendency of fertilising matters is to move upward in the plant as it matures1 and finally to become lodged in the seed4 ,it is for this reason that the cereals prove such an exhaustive crop4 ,that nature1 however1 can in certain cases be very economical of her food-supplies1 is strikingly illustrated by the fact that much of the fertilising matter contained in the mature leaves in autumn passes back into the tree before the leaves fall from it4 ,forms in which ,nitrogen exists in ,plants4 ,the form in which nitrogen is present in the plant is chiefly as albuminoids4 ,as1 however1 albuminoids belong to that class of bodies known as colloids1 which cannot easily pass through porous membranes like those forming the walls of plant-cells1 they are changed during certain periods of the plant's growth into amides1 which are crystalloids1 and consequently able to move freely about in the plant4 ,amides are most abundant in young plants during the period of their most active growth1 and as the plant ripens the amides seem to be largely converted into albuminoids4 ,while the subject is not very clearly understood1 it would seem to be pretty conclusively proved that there is a direct relation between the amount of the phosphoric acid and of the nitrogen absorbed4 ,bearing of above ,facts on ,agricultural ,practice4 ,the bearing of these facts upon practice is obvious4 ,in the first place1 they show how important it is that plants should be well fed when they are young1 and that in the practice of green manuring it is best to plough in the crop when it is in flower1 as no additional benefit is gained by allowing it to ripen1 seeing that no further absorption of fertilising ingredients takes place after the period of flowering4 ,influence of excessive ,manuring of ,crops4 ,the influence of large quantities of manures is seen in the case of certain root crops4 ,it is found1 in such a case1 that while the roots are larger1 they are more watery in composition and of less nutritive value4 ,again1 it seems to be a fact pretty generally known to practical men1 that nitrate of soda seems to have a bad effect on the quality of hay4 ,it would seem1 further1 that the influence of nitrogenous fertilisers on cereals is to increase the percentage of nitrogen in the grain1 but that they have no such influence in the case of leguminous crops4 ,phosphatic manures1 on the other hand1 in the case of leguminous crops1 seem to have the effect of diminishing the amount of nitrogen in the seed4 ,,footnotes3 #bda ,though not necessarily at the same time or to each succeeding crop4 ,there may be comparatively long intervals between the applications of farmyard manure in many cases4 #bdb ,of course what is meant here is the direct influence of such manures4 ,their indirect value may be shown in the soil by the increased crop residues they give rise to4 #bdc ,this is very concisely and clearly put in ,mr ,warington's admirable ',chemistry of the ,farm4' ,,chapter ,,xxiii4 ,,manuring ,,of ,,the ,,common ,,farm ,,crops4 ,in this chapter we shall attempt to summarise briefly the results of experiments on the manuring of some of the commoner crops1 and we shall start with the manuring of cereals4 ,,cereals4 ,as we have already pointed out1 a certain similarity in the manurial requirements of the different members of this class exists4 ,they are characterised1 for one thing1 by the comparatively small quantity of nitrogen they remove from the soil--less than either leguminous or root crops4 ,of this nitrogen the larger proportion--amounting to two-thirds--is contained in the grain1 the straw only containing about a quarter of the total amount of nitrogen in the plant4 ,the amount of phosphoric acid they remove from the soil is not much less than that removed by the other two classes of crops2 but this1 again1 is also chiefly in the grain4 ,it is on this account that the cereals may be regarded1 in a sense1 as exhaustive crops1 seeing that the grain is almost invariably sold off the farm4 ,but1 on the other hand1 owing to the comparatively small demands they make on fertilising ingredients1 cereals will continue to grow on poor land for a longer period than most crops1--a fact of very great importance for mankind4 ,especially benefited by ,nitrogenous ,manures4 ,despite the fact that cereals remove comparatively little nitrogen from the soil1 it is somewhat striking to find that they are chiefly benefited by the application of nitrogenous manures4 ,this fact may be explained by the shortness of the period of their growth1 and the fact that they assimilate their nitrogen in spring and early summer1 and are thus unable to utilise to the full the nitrates which accumulate in the soil during later summer and autumn4 ,as they seem to absorb their nitrogen almost exclusively in the form of nitrates1 they are especially benefited by the application of nitrate of soda4 ,power of absorbing ,silicates4 ,a characteristic feature in the composition of cereals is the large amount of silica they contain4 ,in common with the grasses1 they seem to possess a power1 not possessed by other crops1 of feeding upon silicates4 ,the special manure1 therefore1 required for cereals is a nitrogenous manure1 and that1 as a rule1 of a speedily available character1 such as nitrate of soda or sulphate of ammonia4 ,furthermore1 certain members of the group are also specially benefited by phosphatic manures4 ,we shall now consider individually a few of the more important cereal crops4 ,,barley4 ,of cereal crops barley deserves to be considered first1 owing to the fact that it is1 of all grain crops1 the most widely distributed4 ,in ,england1 in amount1 it comes next to wheat among cereals4 ,its habits have also been studied in a very elaborate and careful manner1 and have been made the subject of many experiments1 both in this country and abroad4 ,period of ,growth4 ,the first point to notice about barley is the fact that its period of growth is a short one4 ,this has a most important bearing on its treatment with manure4 ,it may be said to ripen1 on an average1 in thirteen or fourteen weeks in this country2 although in ,norway and ,sweden its period of growth is much less--viz41 from six to seven weeks4 ,indeed no fewer than three crops have been obtained in one year in certain districts in these countries1 and two crops are common4 ,with regard to the period of its growth1 it differs from wheat1 which in its general manurial requirements it resembles4 ,wheat1 which is largely sown in autumn1 has four or five months' start of barley4 ,from the fact that it is a short-lived crop1 and that its roots are shallower than wheat1 and draw their nourishment chiefly from the surface-soil1 it benefits to a greater extent from liberal manuring than wheat1 which is more independent of artificial supplies of fertilisers4 ,most suitable ,soil4 ,again1 while wheat does well on a heavy soil1 and does not require a fine surface-tilth1 barley does best on a light1 rich1 friable soil4 ,it has1 however1 been very successfully grown on a heavy soil after wheat4 ,barley benefits more than wheat does from the application of superphosphate of lime1 or some other readily available phosphatic manure4 ,this may be accounted for by its shorter period of growth and shallower root system1 which thus prevent it drawing much mineral sustenance from the subsoil4 ,in fact1 spring-sown crops1 as a rule1 benefit more from superphosphate than autumn-sown crops4 ,the exhaustion of a soil under barley is essentially1 as in the case of wheat1 one of nitrogen1 as ,sir ,j4 ,henry ,gilbert has pointed out4#bdd ,farmyard ,manure not suitable4 ,it has been urged1 with some show of reason1 that farmyard manure is not suitable for barley1 as its action is too slow to have much influence on so short-lived a plant1 and that only quick-acting manures should be used4 ,where farmyard manure is applied1 it should be to the preceding crop2 and this is advisable for more reasons than one4 ,importance of uniform ,manuring of ,barley4 ,the use to which barley is put--viz41 for malting purposes--renders the uniformity of its composition a point of great importance4 ,since its quality is very largely influenced by its treatment with manures1 special care has to be exercised in their application4 ,grown as it generally is after roots1 fed off with sheep1 its quality1 it is alleged1 is apt to suffer from the unequal distribution of the manure applied in this way4 ,it has consequently been recommended1 in order to avoid this inequality1 rather to grow a wheat crop immediately preceding the barley4 ,norfolk ,experiments on ,barley4 ,mr ,cooke1 in summing up the results of the interesting ,norfolk experiments on barley1 points out that in these experiments barley always was benefited by nitrogenous manures1 sometimes by superphosphate of lime1 and more rarely by potash2 that of nitrogenous manures those of quickest action exerted the best influence4 ,on an average it was found that #a cwt4 nitrate of soda per acre gave an increase of #h bushels of barley1 and #b cwt4 gave #ad bushels2 while #c_/d cwt4 sulphate of ammonia 7i4e41 the amount containing the same quantity of nitrogen as #a cwt4 nitrate of soda7 gave only #e-a_/b bushels of an increase1 and #a-a_/b cwt4 7 #b cwt4 nitrate of soda7 gave #aj bushels4 ,mr ,cooke recommends the following manures for the barley crop4 ,from #a_/d to #a cwt4 of nitrate of soda1 according to previous treatment of soil2 from #a to #b cwt4 super2 and where it is required1 from #a_/b to #a cwt4 muriate of potash4 ,proportion of ,grain to ,straw4 ,professor ,hellriegel1 the distinguished ,german investigator1 has carried out most elaborate experiments on a small scale1 with a view to investigating the habits of the barley plant4 ,in the most perfectly developed of these plants1 grown under the most favourable conditions1 he found that the grain and straw were about equal in weight4 ,such a proportion of grain is1 however1 never realised in practice1 the proportion of #b of grain to #c of straw being probably the common one4 ,,wheat4 ,wheat occupies the first position amongst cereals1 in respect of extent of cultivation1 in ,england4 ,as a rule it is sown in autumn1 although it is also sown in spring4 ,it is generally taken after rotation grasses or a leguminous crop1 such as peas or beans1 or after potatoes or roots4 ,unlike barley1 it does best on a clay soil1 or at any rate on a firm soil1 and requires a moist seed-bed4 ,from the fact that wheat is often sown after such a crop as potatoes or a root crop to which a liberal application of manure has been given1 it is not so necessary to manure it except with a top-dressing of nitrate of soda4 ,in short1 it is usually considered highly desirable to get land into good heart before wheat1 so that the wheat may obtain its nourishment from the residue of the previous crop and the farmyard manure previously applied4 ,although1 therefore1 as a rule1 the only manure it will be found necessary to add to wheat is a nitrogenous manure1 such as nitrate of soda or sulphate of ammonia1 still there are circumstances in which it will be well to supplement these by phosphatic or even potassic manures4 ,on a light soil it may be advisable to add superphosphate of lime1 guano1 or bone-meal1 in quantities of #b to #c cwt4 per acre1 in addition to a nitrogenous manure4 ,rothamsted ,experiments on ,wheat4 ,of experiments carried out on the growth of wheat1 those which have now been in progress for over half a century at ,rothamsted are the most valuable and famous4 ,in these experiments the comparative value of nitrogen and mineral manures on this crop was strikingly exemplified4 ,the former gave a most marked increase in the crop1 while with the latter little or no increase was obtained4 ,a combination of nitrogenous and mineral manures1 on the other hand1 gave the most striking results4 ,an explanation of these results may be afforded by the fact that in ordinary farming an excess of mineral matter1 as compared with nitrates1 is returned to the soil in the crop residues and in the straw of the farmyard manure4 ,of nitrogenous manures1 nitrate of soda1 on the whole1 showed better results than sulphate of ammonia4 ,continuous ,growth of ,wheat4 ,the possibility of growing fair crops of wheat year after year for fifty years on the same land1 and that without any manure whatever1 is among the most striking of the results of these famous ,rothamsted wheat experiments4 ,flitcham ,experiments4 ,in conclusion1 we may refer to ,mr ,cooke's ,flitcham experiments4 ,these were carried out for the purpose of ascertaining the most suitable manure for the wheat crop under different conditions4 ,it will be sufficient here to give the recommendations made by ,mr ,cooke as the practical outcome of these experiments4 ,he recommends the application of #aj tons of farmyard manure on light or mixed soils1 after rotation seeds1 ploughed in in the autumn1 with from #a_/d to #a cwt4 of nitrate of soda1 sown in the spring4 ,in certain cases farmyard manure will be sufficient without the nitrate of soda4 ,when farmyard manure is not available1 the most effective and economical substitute is #d cwt4 per acre of rape-cake1 ploughed in in the autumn1 or #a cwt4 of sulphate of ammonia1 sown in the spring1 with1 in either case1 #a cwt4 of nitrate of soda as a spring top-dressing4 ,in addition to the above1 on land in doubtful agricultural condition1 or exceptionally deficient in one or other of these ingredients1 ,mr ,cooke recommends the addition of #b cwt4 superphosphate1 or #a cwt4 muriate of potash1 or both of these manures1 ploughed or harrowed in in autumn4 ,,oats4 ,like barley1 oats are generally sown in spring1 and1 like barley1 may be described as a shallow-rooted crop4 ,they require1 therefore1 manures which are readily available1 and their demands on the different fertilising ingredients are very similar to barley4 ,the manures which will pay best1 consequently1 for oats1 are nitrate of soda1 used as a top-dressing1 and superphosphate of lime1 applied along with the seed4 ,probably upon no other crop is nitrate of soda so safe and so effective as upon oats4 ,in some respects1 however1 oats differ strikingly from barley4 ,a very hardy ,crop4 ,in the first place1 oats are a much hardier crop than barley or wheat4 ,they can grow on a wonderfully wide range of soil1 and under comparatively adverse circumstances1 both of climate and situation4 ,they are better suited for a damp climate such as our own than a warm climate4 ,they may be described as of all crops the least fastidious1 and will flourish on sandy1 peaty1 or clayey soils4 ,while this is so1 they show a preference for soils rich in decayed vegetable matter4 ,it is for this reason that they flourish so well on soils freshly broken up from pasture1 and are often the first crop to be grown on such soils4 ,require mixed ,nitrogenous ,manuring4 ,stoeckhardt has found1 in experiments on the manuring of the oat crop1 that they greedily absorb nitrogen during nearly the whole period of their growth1 and that1 consequently1 it is desirable to manure them with a mixed nitrogenous manure which shall contain nitrogen1 both in a readily available form to supply the plant during the early stages of its growth1 and in a less available form for the later stages of growth4 ,he was of the opinion that in this way a continuous and satisfactory growth of the crop would be promoted4 ,arendt's ,experiments4 ,the oat-plant has been made the subject of many elaborate investigations4 ,of these1 those carried out by ,arendt are the most elaborate and best known4 ,in these experiments the composition of the oat-plant at different stages of growth was investigated4 ,it was found that the oat-plant increased during the whole period of its life1 and that two-thirds of the nitrogen absorbed was absorbed during the later period of growth4 ,it has since been shown1 however1 that the absorption of nitrogen is very much influenced by circumstances4 ,indeed its composition is peculiarly susceptible to the influence of manures1 and especially the influence of weather4 ,thus ,arendt found that the assimilation of nitrogen is checked by cold wet weather2 while1 on the other hand1 it is promoted by warm dry weather4 ,the grain of oats grown in warm seasons is better developed1 and in composition more nutritious 7i4e41 contains more nitrogen71 than that of oats grown in wet seasons1 while the reverse is the case with the straw4 ,avenine4 ,a point of considerable interest in connection with the composition of oats is the fact that it contains a body which exerts a strikingly stimulating effect on the nervous system of the animal1 and to which the name avenine has been given4 ,quantities of ,manures4 ,the quantities of manures which may be applied to the oat crop are similar in amount to those which ought to be applied to barley--from #a_/b to #a cwt4 of nitrate of soda1 and from #b to #c cwt4 superphosphate of lime4 ,very often1 however1 the oat crop receives directly little or no manure4 ,in the ,highland and ,agricultural ,society of ,scotland's experiments1 sulphate of ammonia was found to be of very much less value than nitrate of soda as a manure for oats4 ,potash manures1 especially muriate of potash1 had a very beneficial effect4 ,the general conclusions drawn from these experiments were1 that the treatment of the land should be such as to accumulate organic matter in it1 to prevent too great a loss of moisture1 and to provide the young plant with manures that come speedily into operation4 ,,grass4 ,the manuring of grass is a question of very great interest and importance1 but is1 at the same time1 beset with peculiar difficulties4 ,grass is grown under two conditions--first1 that grown on soils exclusively set apart for its continuous growth 7permanent pasture72 and secondly1 that grown for the purpose of being converted into hay and of providing pasture in the ordinary rotation of crops 7rotation seeds74 ,the manuring of the former is somewhat different from the manuring of the latter4 ,effect of ,manure on ,herbage of ,pastures4 ,the nature of the herbage growing on pasture is very much influenced by the manure applied4 ,this1 indeed1 is one of the most noteworthy features connected with the manuring of grass1 and has been especially observed in the ,rothamsted experiments1 where the influence of the different manures on the various kinds of herbage has been investigated with great care4 ,the herbage constituting pasture is1 as every farmer knows1 of a varied description4 ,we have in pastures a mixture of plants belonging both to the gramineous and leguminous classes1 as well as a variety of weeds4 ,now the result of the application of different manures tends respectively to foster the different kinds of grasses4 ,thus when one kind of manure is applied1 grasses of one kind tend to predominate and crowd out grasses of another4 ,it has been found that the more highly pasture-land is manured the simpler is the nature of its herbage 7that is1 the fewer are the different kinds of herbage growing on it74 ,unmanured pasture1 on the other hand1 is more complex in its herbage4 ,the result is1 that the application of manure to pasture-land is attended with certain dangers4 ,to maintain good pasture it is desirable to effect a proper balance between the different kinds of grasses4 ,for this reason permanent pasture may be said to be1 of all crops1 the least commonly manured4 ,as a rule it is only manured by the droppings of the cattle and sheep feeding upon it4 ,influence of ,farmyard ,manure4 ,it is found that the influence of farmyard manure upon the composition of the pasture does not tend1 to the same extent1 to the undue development of one type of herbage over another2 and in this respect it is probably to be preferred to artificial manures4 ,the same reasons1 however1 do not hold with regard to rotation seeds1 where an abundant growth is desired1 and complexity of herbage is not so important4 ,a further reason which exists for the manuring of meadow-land is the greater impoverishment of the soil taking place under such conditions4 ,as illustrating the influence of different manures on different kinds of herbage1 it may be mentioned that in ,new ,england wood-ashes1 a manure commonly used there1 have been observed1 when applied to pasture1 to bring in white clover1 and that the application of gypsum had the same effect4 ,an explanation of this fact may be found in the influence of potash on leguminous crops4 ,the chief value of wood-ashes as a manure is due to the large percentage of potash they contain1 while the value of gypsum is probably to be accounted for by the fact that it has an indirect action1 and sets free potash from its inert compounds in the soil4 ,in the ,rothamsted experiments this point has been verified1 and potash has been shown to increase the proportion of leguminous plants on a grass-field4 ,nitrogenous manures1 on the other hand1 more especially sulphate of ammonia1 have been found to increase the proportion of grasses proper1 and to diminish the proportion of leguminous plants4 ,the effect of farmyard manure1 while less marked in inducing simplicity of herbage1 has a similar effect to sulphate of ammonia2 while phosphates and other mineral manures exercise an influence similar to that of potash4 ,mixtures of mineral and nitrogenous manures gave the largest returns obtained1 but their influence was to increase the proportion of grasses proper4 ,sewage irrigation also tends chiefly to develop grasses4 ,influence of ,soil and ,season on ,pastures4 ,manures are not the only factors influencing the quality of pastures4 ,the nature of the soil1 as well as the age of the pasture and the character of the season1 exert a very considerable influence4 ,grass growing on damp or badly drained soil is invariably of poor quality1 the coarser grasses predominating4 ,old pastures1 again1 are generally of better quality than new ones4 ,,manuring ,,of ,,meadow-,,land4 ,nitrate of soda is a common manure for grass grown for hay4 ,it is often applied at the rate of #b or #c cwt4 per acre4 ,it is best1 however1 to apply it in smaller doses4 ,on soils where lime is abundant1 superphosphate may be applied1 if necessary1 at the rate of #b or #c cwt4 per acre1 or bones at a similar rate4 ,basic slag has been found to meet with good results as a manure for grass-land1 especially where the soil is rich in organic matter4 ,bangor ,experiments4 ,mr ,gilchrist of ,university ,college1 ,bangor1 as a result of numerous experiments carried out in different parts of ,wales1 recommends for rye-grass and clover hay on land in good condition #a cwt4 of nitrate of soda or sulphate of ammonia per acre1 the former being applied about the middle of ,april1 the latter during ,march4 ,for land in poor condition1 the addition of #b cwt4 of superphosphate is recommended--this to be applied some time between ,december and ,march4 ,farmyard manure may be usefully applied to young grass and clover seeds in the autumn1 more especially on light soils4 ,for meadow-land which is growing hay every year1 ,mr ,gilchrist further recommends the following #d-;course rotation of manuring3-- ,first year1 #ae tons farmyard manure1 applied in the autumn4 ,second year1 #a cwt4 nitrate of soda4 ,third year1 #d cwt4 basic slag or #c cwt4 superphosphate and #a cwt4 nitrate of soda4 ,fourth year1 #a cwt4 nitrate of soda4 ,norfolk ,experiments4 ,mr ,cooke1 from his ,norfolk experiments1 recommends the following manures for rotation seeds3-- ,one to #a-a_/b cwt4 nitrate of soda as a top-dressing in early spring4 ,where the clover plant is a good one1 and it is particularly desired to cultivate it1 he recommends as a dressing #a cwt4 of muriate of potash per acre1 to be applied immediately after the clover is sown4 ,the practice of dressing growing seeds in their first winter has1 so far as the experiments in ,norfolk go1 less to recommend it than the earlier dressing4 ,,manuring ,,of ,,permanent ,,pastures4 ,in this case the manure should be applied so as not to impair the quality of the herbage4 ,slow-acting manures are consequently best1 such as basic slag or bones1 which have been found to be of special value4 ,on wet or marshy land after draining1 lime is perhaps one of the best manures to apply in the first instance4 ,as we have already said1 farmyard manure will do more to maintain the quality of pasture than any kind of artificial manure4 ,mr ,cooke is of opinion that no system of manuring yet discovered will both thicken and improve the herbage at all equally in success to the careful and regular feeding upon the grass of cattle or sheep1 the animals having a good allowance of decorticated cotton-cake1 or even of linseed-cake4 ,,roots4 ,of all crops roots may be said to require the most liberal application of manure1 and to respond most freely to it4 ,they contain large quantities of the fertilising ingredients--nitrogen1 phosphates1 and potash--and may be regarded as exceedingly exhaustive crops4 ,this is especially the case with regard to mangels1 which make particularly large demands on a soil's fertilising ingredients4 ,turnips are characterised by the large amount of sulphur they contain2 and1 according to some1 this explains the beneficial effect which gypsum has when applied to them as a manure4 ,this1 however1 is more probably to be explained by the indirect action of gypsum in setting free the potash of the soil4 ,the fact that the successful cultivation of root crops depends on the application of large quantities of manure1 is recognised in practice1 as they receive the most manure of any crop of the rotation4 ,roots flourish best on a light soil which is neither too wet nor too dry2 but with liberal manuring and careful tillage1 they may be said to do well on any soil4 ,mangels are generally more benefited by the application of nitrogenous manures than are turnips or swedes1 which1 it would seem1 have a greater power of absorbing nitrogen from the soil than the first-named crop2 but it is a mistake to suppose that any of the root crops are not dependent on a ready supply of nitrogen2 and the fact that large crops of turnips can often be grown by the application of superphosphate alone1 may be taken as a proof that the soil contains plenty of nitrogen4 ,mangels are1 from their deeper roots1 more capable of drawing their supply of phosphoric acid from the soil than turnips4 ,they respond1 therefore1 as a rule1 less freely than turnips or swedes to an application of superphosphate4 ,generally speaking1 we may say that the characteristic manure for turnips is superphosphate1 and that for mangels is a nitrogenous manure such as nitrate of soda or sulphate of ammonia4 ,a special reason for manuring root crops is the fact that they are more liable to disease than other crops2 and this is especially the case in the early stages of their growth4 ,one of the great benefits conferred on the turnip crop by an application of superphosphate1 is the help it gives the crop to pass safely the critical period of its growth4 ,the superphosphate is best drilled in with the seed1 in quantities varying from #c to #e cwt4 ,in ,scotland1 it may be well to point out1 the manure applied to this crop is very much in excess of the amount customarily applied in ,england2 for in the former country larger applications of manure may be profitably employed4 ,roots generally receive a large dressing of farmyard manure4 ,salt has been found in some districts to have a very good effect on the mangel crop1 and potash is often found to amply repay application4 ,influence of ,manure on ,composition4 ,a most interesting point in connection with the manuring of roots is the effect of manure on their composition4 ,this has been most elaborately investigated at ,rothamsted and elsewhere4 ,thus it has been found that the effect of the application of excessive quantities of nitrogenous manures is to produce too great a development of leaves at the expense of the roots4 ,nitrogenous ,manures increase ,sugar in ,roots4 ,nitrogenous manures also tend to increase the proportion of sugar and diminish the proportion of nitrogenous matter in roots4 ,this has an important bearing on the treatment of roots which are cultivated for their sugar1 such as beets1 in the growth of which nitrate of soda is the chief artificial manure applied4#bde ,the leaf1 it may be pointed out1 contains a larger percentage of dry matter1 both in swedes and in turnips1 than the root4 ,amount of ,nitrogen recovered in ,increase of ,crop4 ,with regard to the amount of nitrogen recovered in the increased crop of mangel and roots when manured with different nitrogenous manures1 it was found at ,rothamsted1 as an average of six years1 that the following percentages of nitrogen were recovered3 ,when nitrate of soda was applied1 #fj per cent of the nitrogen it contained was recovered in the increased crop2 when ammonia salts were applied1 #eb per cent2 when rape-cake was used1 #ej per cent2 and when a mixture of rape-cake and ammonia salts was used1 #df per cent4 ,it may be pointed out that the influence of season and climate on the composition of root crops is very great--greater1 indeed1 than on any other crop4 ,like oats1 turnips grow better in ,scotland than in ,england1 the moister climate of the former country being more suitable for their maximum development1 and hence the economy of maximum dressings in ,scotland4 ,norfolk ,experiments4 ,in conclusion1 a few words may be said on the ,norfolk experiments1 carried out under the direction of ,mr ,cooke for the purpose of ascertaining the best and most economical manure for mangels and swedes on different ,norfolk soils4 ,in most of these experiments it was found that superphosphate had not much effect in producing increase of crop in the case of mangels2 that the best nitrogenous manure was nitrate of soda2 and that on the whole it was not economical to apply farmyard manure at the rate of more than #aj tons per acre4 ,it was further found that1 although either potash or common salt gave a decided increase in weight of roots1 it was not necessary to give both these manures at once1 either of them being about as effective as the other4 ,mr ,cooke recommends the following manures as best suited for mangels--viz41 #b cwt4 nitrate1 #c cwt4 common salt1 and #b cwt4 superphosphate4 ,upon certain soils peculiarly adapted to mangels1 and in warm localities where larger crops than #be to #cj tons per acre are habitually grown1 it would probably pay to increase or to double the above quantity of nitrate of soda4 ,ten tons of farmyard manure may1 if preferred1 be substituted for all or a part of the nitrate of soda1 or may even be used in addition to it1 according to the resources of the farmer in respect of it1 and the return he desires to get from the dung in the first year of application or in future ones4 ,it is best to apply the nitrate of soda in two instalments--half at the time of seeding1 and half as a top-dressing immediately after the first hand-hoeing of the roots4 ,a third dressing may often be given with advantage a month later4 ,manure for ,swedes4 ,as a complete and economical dressing for swedes in ,norfolk1 ,mr ,cooke recommends #c to #d cwt4 superphosphate1 #a cwt4 sulphate of ammonia1 and #a_/b cwt4 of muriate of potash4 ,occasionally it may be found advisable to reduce the quantity of sulphate of ammonia1 or to leave it out altogether2 and in other cases the potash may be judiciously omitted4 ,the entire mixture should be sown at the time of drilling the turnips4 ,if farmyard manure is used--and if used it should be applied in a well-decomposed state--no other manure than #c cwt4 of superphosphate will be required4 ,highland ,society's ,experiments4 ,valuable experiments have been carried out on the subject of manuring of turnips by ,dr ,a4 ,p4 ,aitken1 for the ,highland and ,agricultural ,society of ,scotland4 ,the following are some of the results to be gathered from these experiments4 ,the effect of a dissolved phosphate as compared with a ground phosphate is to produce a turnip of less feeding value4 ,superphosphate had a better effect when applied in ,april than when applied with the seed in ,june4 ,it was further found that when the nitrogenous manure was given entirely in the form of nitrate of soda or sulphate of ammonia1 the latter produced a denser and sounder turnip4 ,lastly1 with regard to the application of potash1 it was found that the best way was to apply it several months before sowing4 ,the effect of potash manures is to increase the amount of turnips1 but to retard the ripening of the bulbs4 ,the effect of excessive potash manuring is to greatly injure the crop4 ,manuring for rich ,crops of ,turnips4 ,in ,dr ,aitken's own words3 ,in order to grow a large and at the same time a healthy and nutritious crop of turnips1 such a system of manuring or treatment of the soil1 by feeding or otherwise1 should be practised as will result in the general enriching and raising of the condition of the land1 so that the crop may grow naturally and gradually to maturity4 ,for that purpose a larger application of slowly acting manures1 of which bone-meal may be taken as the type1 is much better suited than smaller applications of the more quickly acting kind4 ,a certain amount of quickly acting manure is very beneficial to the crop1 especially in its youth2 but the great bulk of the nourishment which the crop requires should be of the slowly rotting or dissolving kind1 as uniformly distributed through the soil as possible4 ,experiments by the ,author4 ,experiments by the author on turnip-manuring1 carried out in different parts of the ,south and ,west of ,scotland1 showed that while farmyard manure is valuable in giving the crop a good start and bringing it well forward during the period of germination and early growth1 by supplying a certain amount of easily assimilable plant-food1 and in the case of dry weather attracting a quantity of moisture1 its application in quantities of #bj or even #aj tons per acre can scarcely be regarded as profitable1 giving to farmyard manure a nominal value of a few shillings a ton4 ,in these experiments slag proved itself a most valuable manure1 indeed one of the most economical of all the manures experimented with4 ,they further showed that heavy dressings with superphosphate1 amounting to as much as #h cwt4 per acre1 are1 from an economical point of view1 as a rule justifiable in ,scotland2 and that nitrate of soda and sulphate of ammonia possess practically equal value as a manure for turnips4 ,in almost every one of the experiments the benefit of supplementing superphosphate with nitrogenous manure was shown4 ,potash was also found in many cases to be a thoroughly paying manure for the turnip crop1 when it was applied along with nitrogen and phosphates2 but when applied alone1 far from exercising any appreciable benefit1 it seemed to exert an injurious action4 ,,potatoes4 ,potatoes are often classed along with the root crops1 and in their manurial requirements they offer many points of similarity4 ,next to root crops1 they may be said to make the most exhaustive demands on the soil1 and therefore require a liberal general manuring4 ,a point of importance in the manuring of potatoes is a good tilth in the soil1 so as to enable a free expansion of the tubers to take place4 ,they may be said to grow best on deep warm soils2 but1 like roots1 if liberally manured1 they may be successfully grown on any kind of soil4 ,farmyard manure has long been regarded as specially valuable for the potato crop4 ,in many parts of ,scotland it is applied in enormous quantities1 ranging from #bj to even #dj tons per acre4 ,there can be little doubt that the value of farmyard manure1 as well as other bulky manures1 for the potato crop1 is partly due to their mechanical influence on the soil4 ,potatoes are surface-feeders1 and require their food in a readily available condition4 ,it is found desirable1 therefore1 to supplement farmyard manure by readily available artificial manures4 ,potatoes repay the application of a mixed manure containing all the fertilising ingredients--nitrogen1 phosphoric acid1 and potash--better than most crops4 ,highland ,society's ,experiments on ,potatoes4 ,the nitrogen is1 according to the ,highland ,society's experiments1 best applied in the form of nitrate of soda4 ,sulphate of ammonia does not seem1 when farmyard manure is also applied1 to have an equally valuable effect1 as it influences the size of the tuber1 producing an undue proportion of small potatoes4 ,when no farmyard manure is applied1 however1 sulphate of ammonia seems to have a good effect1 especially in wet seasons4 ,with regard to the nature of the phosphatic manure to be applied1 superphosphate is to be preferred4 ,potatoes make large demands on potash1 and consequently require potassic manures4 ,in consequence of the fact that they receive large applications of farmyard manure1 the necessity for adding potash in the form of artificial manures does not generally exist4 ,potash1 if applied in too large quantities1 has been found to exert a deleterious effect4 ,we have already pointed out that muriate of potash tends to produce a waxy potato4 ,the ,rothamsted ,experiments with ,potatoes4 ,the ,rothamsted experimenters have very fully investigated the conditions of the manurial requirements of potatoes4 ,in these experiments potatoes were grown year after year in the same field4 ,it was found that the effect of mineral manures alone was greater than the effect of nitrogenous manures alone1 and that of mineral manures phosphates1 as a rule1 had a better effect than potash2 that under the action of the growth of potatoes a greater exhaustion of phosphates than of potash takes place in the soil2 and lastly1 that it is essential to have an abundant supply of the different fertilising ingredients in order to grow successful crops4 ,in the ,rothamsted experiments1 the slow action of farmyard manure in supplying fertilising ingredients to the potatoes is strikingly demonstrated4 ,thus1 although farmyard manure was applied at such a rate that more than #bjj lb4 of nitrogen were added to the soil1 the result was inferior to that obtained from the application of #hf lb4 of nitrogen applied in the form of readily available artificial manure4 ,effect of ,farmyard ,manure on ,potatoes4 ,it may be said1 in this respect1 that the potato is less able to utilise the fertilising ingredients of farmyard manure than any other of the farm crops4 ,yet1 despite this fact1 farmyard manure has been found to be one of the best manures to apply4 ,the reconciliation of these seemingly contradictory statements depends on the influence exerted by the farmyard manure on the mechanical condition of the soil1 rendering it more porous and easily permeable to the surface-roots1 upon the development of which the success of the crop so much depends4 ,the beneficial effect of farmyard manure is also doubtless due to the increased temperature which large applications of it produce in a soil4 ,sir ,j4 ,henry ,gilbert1 in his well-known ,cirencester ,lecture on the ,growth of ,potatoes1 cites several examples of the manurial treatment of potatoes in different parts of the country4 ,in ,forfarshire1 farmyard manure or stable manure is largely employed 7at the rate of #ab to #ad tons1 and in some cases even #bj tons per acre71 and it is also largely supplemented by artificial manures4 ,these latter are applied to the extent of about #aj cwt41 and consist of superphosphate1 dissolved bones1 and potash salts4 ,six tons of potatoes are considered a fair crop4 ,in ,east ,lothian the manuring is similar1 with the exception that farmyard manure is applied in even larger quantities--#cj to #dj tons being often used4 ,sometimes potatoes are grown with artificial manures alone4 ,it would seem that the usual crop of potatoes ranges from #d to #h tons per acre4 ,manuring of ,potatoes in ,jersey4 ,the manuring of the potato crop1 so largely grown in ,jersey in the ,channel ,islands1 is of interest4 ,potatoes are there grown two or three years1 then corn1 then grass for a few years1 then potatoes again1 no special rotation of crops being followed4 ,either farmyard manure or sea-weed is applied at the rate of #be to #cj tons per acre1 supplemented by #h to #ab cwt4 of artificial manures4 ,these statements show how prevalent the practice of heavily manuring the potato crop is4 ,the ,influence of ,manure on the ,composition of the ,potato4 ,the influence of manure on the composition of the potato crop is of much interest4 ,potatoes grown without manure1 just as in the case of roots1 are found to have a larger percentage of nitrogen than potatoes grown with manure4 ,the effect of manuring1 therefore1 is to increase the proportion of starch1 which is the most important constituent of the potato4 ,mineral manures have a greater effect in increasing the percentage of starch than purely nitrogenous manures2 but when used together1 a still greater increase is obtained than when used singly4 ,the effect of nitrogenous manures on the composition of roots and potatoes is thus seen to be similar4 ,in the case of both crops the effect is to increase the proportion of the characteristic carbohydrate constituent1 which in roots is sugar1 and in potatoes starch4 ,potatoes1 like roots1 are also much influenced by the season4 ,the effect of season and manuring on the potato disease is worthy of notice4 ,wet seasons are favourable to the development of the disease4 ,it has been found that in a highly nitrogenous manured crop the proportion of diseased tubers is greater than in a non-manured crop4 ,,leguminous ,,crops4 ,we have already referred to the manuring of crops of the leguminous class in discussing the manuring of meadows and permanent pasture4 ,it was there pointed out that the tendency of certain manures was to encourage the growth of the leguminous plants of the herbage1 while other manures had the effect of encouraging those of the gramineous class4 ,it was pointed out that a manure which had this effect was potash1 or any manure which owed its characteristic action to the fact that it supplied potash to the soil or set it free in the soil4 ,leguminous ,plants benefit by ,potash4 ,this is one of the most important points to notice in manuring leguminous plants4 ,just as we can say that nitrogenous manures are specially beneficial to cereals1 and phosphatic manures to roots1 so potash is the special manure for leguminous crops4 ,nitrogenous ,manures may actually be hurtful4 ,but we have1 further1 an even more striking characteristic of leguminous crops to notice4 ,we have seen that1 with regard to the crops already discussed1 while there are cases in which a fertilising ingredient may be of no value1 or may positively exert a hurtful action on the crops1 such cases are only exceptional4 ,with regard to leguminous crops1 however1 we find that almost invariably they derive little or no benefit from the use of artificial nitrogenous manures4 ,and this is all the more striking since they contain large quantities of nitrogen in their composition--twice as much as the cereals4 ,the fact1 which has long been noticed with regard to certain members of this class of plants1 such as clover1 that not only do they contain a large amount of nitrogen1 but that by growing them on a soil the soil is largely enriched in this valuable fertilising constituent1 has long waited for a satisfactory explanation1 which at last has been forthcoming4 ,the discovery that leguminous crops can draw on the boundless store of nitrogen present in the air has done much to clear up the mystery4 ,there are1 however1 other problems with regard to the growth of leguminous plants which still await solution4 ,clover-sickness4 ,one of these is the fact that land on which a leguminous crop like clover has been growing for a number of years becomes unfit to support its growth any longer4 ,such a soil is termed clover-sick2 and many have been the theories put forward to explain the phenomenon1 but none of them can be regarded as satisfactory4 ,the knowledge that leguminous plants have the power of deriving their nitrogen from the air1 furnishes us with an economical means of enriching our soils in nitrogen4 ,by growing leguminous crops alternately with cereals1 for example1 the air should be made to furnish the necessary nitrogenous manure4 ,as a matter of fact1 modified forms of such a practice have long been in use--indeed the ordinary rotations of crops are1 to a certain extent1 adaptations of this practice4 ,alternate ,wheat and ,beans ,rotation4 ,an interesting experiment carried out at ,rothamsted may be here cited which illustrates in a striking manner the truth of the above statement4 ,wheat and the leguminous crop beans were grown alternately4 ,it was found that almost as much wheat 7containing nearly as much nitrogen7 was yielded in eight crops of wheat so grown as was yielded by sixteen crops of wheat grown consecutively in an adjoining field4 ,the most commonly cultivated leguminous crops are clover1 beans1 and peas4 ,clover having been already discussed1 we need only say a word or two on the manuring of beans and peas4 ,,beans4 ,beans do best on strong land1 and1 unlike some of the crops considered1 do not require a particularly fine tilth4 ,they are generally grown after cereals1 and as a rule are sown in spring4 ,more rarely1 however1 they are sown in autumn4 ,spring-sown beans take about seven months to come to maturity4 ,they are much affected1 like other crops1 but to a greater extent1 by the nature of the season--a wet season inducing an undue development of straw4 ,manure for ,beans4 ,in common practice the manure used for the bean crop is farmyard manure1 applied to the soil in autumn after the harvest of the wheat1 barley1 or other cereal crop grown4 ,so common is this practice1 that the belief commonly exists that farmyard manure is necessary for a successful bean crop4 ,but experiments conducted at the ,highland ,society's ,experiment ,station at ,pumpherston show that full crops of beans may be grown with the aid of artificial manures on soils which have received no application of farmyard manure for ten years4 ,relative ,value of ,manurial ,ingredients4 ,in the ,appendix#bdf will be found a table giving the results of manurial experiments with the nitrogenous1 phosphatic1 and potash manures on beans1 carried out by ,dr ,a4 ,p4 ,aitken at the ,highland ,society's ,experiment ,station4 ,from these experiments it will be seen that the application of phosphates and nitrogenous manures1 either alone or together1 exerted a comparatively small effect in increasing the yield of beans compared with that obtained with potash1 either alone or combined with phosphates4 ,as ,dr ,aitken says1 ,without potash in the manure1 the other two ingredients are of very little use1 unless1 indeed1 the land be very rich in potash4 ,gypsum4 ,gypsum has a good effect on the bean crop1 both on account of the lime it contains1 and of its indirect action in setting free potash4 ,superphosphate is a much better manure than insoluble phosphates1 and similarly1 in the few cases where nitrogenous manures are beneficial1 the speediest acting are best4 ,hence nitrate of soda is to be preferred to other nitrogenous manures4 ,when it is applied1 it should be applied in small quantities4 ,a slow-acting nitrogenous manure is positively injurious2 so also1 according to ,dr ,aitken1 is nitrate of soda1 applied as a top-dressing to the crop4 ,of potash manures1 the muriate seems to be more effective than the sulphate4 ,effect of ,manure on ,composition of ,crop4 ,lastly1 we may refer to the effect of manures on the composition of the crop4 ,this is1 on the whole1 very slight1 especially when compared with the effect manures exert on the composition of such crops as turnips or potatoes4 ,it is the quantity and not the quality of the crop which the manure affects in the case of beans4 ,,peas4 ,peas are not grown to anything like the same extent as beans4 ,as a rule1 when they are cultivated it is along with beans1 when they are necessarily manured in a similar manner4 ,if grown alone1 however1 it may be well to point out that peas do best1 unlike beans1 on light1 friable1 chalky loam4 ,when grown in clay they tend to develop an undue amount of straw4 ,the effect of season on the crop is similar to that exerted on the bean crop4 ,in conclusion1 it may be pointed out that it is alleged that the effect of farmyard manure on peas is to force the straw4 ,in concluding this chapter a word or two may be said on the manuring of two other crops which are cultivated to a considerable extent in this country--viz41 hops and cabbages4 ,,hops4 ,the requirements of the hop crop in the matter of manures are rather singular4 ,it has been pointed out that in the case of most crops quick-acting manures are to be preferred to slow-acting manures4 ,with hops1 however1 the case is very different2 for they require1 and cannot be successfully cultivated without1 slow-acting manures4 ,hops are especially benefited by bulky nitrogenous manures--such as shoddy1 horn-meal1 hide-scraps1 hoofs1 rape-dust1 c42 and it is only when quick-acting manures are applied along with such slow-acting manures that they will exercise their full influence4 ,it is best to manure hops twice a-year1--in spring with farmyard manure1 supplemented by a slow-acting nitrogenous manure1 such as shoddy2 and again in summer with a more quickly acting manure4 ,the dressings applied to hops are enormous relatively to those used on other farm crops4 ,,cabbages4 ,cabbages belong to that class of crops known as gross feeders1 to which any sort of manure1 applied in almost any quantities1 does not come amiss4 ,cabbages grow best on good loams with a well-drained porous subsoil1 although they also do well on clay soils4 ,the quantity of fertilising ingredients1 especially potash1 which a large crop of cabbage removes from the soil is very great4 ,they consequently require large quantities of manure1 and are especially benefited by saline manures--such as kainit and common salt--and liberal doses of nitrate of soda1 which may be regarded as the most effective of manures for all the cabbage tribe4 ,farmyard manure may be applied with benefit in larger quantities than it would be applied to any other crop4 ,,footnotes3 #bdd ,see his ,lecture on the ,growth of ,barley4 #bde ,small roots are found to contain a larger proportion of sugar than large roots4 #bdf ,see ,note ,i41 p4 #ecj4 ,,appendix ,,to ,,chapter ,,xxiii4 ,,note ,i4 7p4 #ebf74 ,,experiments ,,on ,,the ,,manuring ,,of ,,beans4 ,experiments with beans carried out at the ,highland and ,agricultural ,society's ,experiment ,station at ,pumpherston1 showing the effect of potash3-- ,no4 of ,bushels dressed plots4 ,kind of manure4 grain1 per acre4 #bg4 ,no manure #b-a_/b #ab4 ,phosphate 7bone-ash7 #e-a_/f #ah4 ,nitrate #f-a_/d #ba4 ,phosphate and nitrate #e-a_/c #bb4 ,potash #bf-a_/b #ag4 ,potash and phosphate #db-a_/c #aj4 ,potash1 phosphate1 and nitrate #de-a_/b #ch4 ,potash1 phosphate1 nitrate1 and gypsum #ea ,,chapter ,,xxiv4 ,,on ,,the ,,method ,,of ,,application ,,and ,,on ,,the ,,mixing ,,of ,,manures4 ,having considered the manuring of the different crops1 we may now pass on to the consideration of some points in the method of application and on the mixing of manures4 ,equal ,distribution of ,manures4 ,a most important object in applying manures is to effect equal distribution of the manure in the soil4 ,this is often1 however1 unusually difficult to do1 especially in the case of artificial manures1 where the quantity to be spread over a large area of the soil is extremely small4 ,the difficulty in the case of farmyard or other very bulky manure is not so great4 ,in order to overcome this difficulty in the case of artificial manures1 it is often advisable to mix them with some such substance as sand1 ashes1 loam1 peat1 or salt4 ,the manure is thus diluted in strength1 and a very much larger bulk of substance is obtained to work with4 ,circumstances must decide which of these substances to use4 ,if the soil be a heavy clay1 the addition of sand or ashes may have an important mechanical effect in improving its texture2 while1 on the other hand1 if it be a light soil1 the addition of peat may improve its mechanical condition4 ,it must also be remembered that peat itself contains a large amount of nitrogen1 and thus forms a manure of some value4 ,in using loam or peat to mix with artificial manures1 they should be first dried and then riddled2 while if ashes be used1 they should be previously reduced to a fine state4 ,wood-ashes1 however1 must be used with caution1 and ought not to be mixed with ammoniacal manures1 as they are apt to contain caustic alkali1 which would tend to drive off the ammonia in a volatile state4 ,it has been recommended1 in order to save trouble and effect equal distribution1 that the manure to be applied should always be made up to the same amount1 so that the farmer by experience may ascertain the rate at which to apply it4 ,and here it may be well to say a word or two on the subject of mixing manures--a subject with which the farmer is not always so conversant as it is desirable in the interests of his own pocket he should be4 ,mixing ,manures4 ,it is to be feared that not unfrequently indiscriminate mixing may cause very serious loss in the most valuable constituent of a manure4 ,it may be well1 therefore1 to point out one or two of the causes of the loss that is apt to ensue on the mixing of different kinds of manures together4 ,as the subject depends for its clear comprehension on certain chemical elementary principles1 it may be well for the benefit of non-chemical readers to state these pretty fully4 ,risks of ,loss in ,mixtures4 ,the risks of loss which may occur from the mixing of artificial manures together may be of different kinds4 ,one is the risk of actual loss of a valuable ingredient through volatilisation2 another is the risk of the deterioration of the value of a mixture through change of the chemical state of a valuable ingredient4 ,undoubtedly the most common and most serious source of loss is the former4 ,of the three valuable manurial ingredients--nitrogen1 phosphoric acid1 and potash--only the first is liable to loss by volatilisation1 and this generally only when the nitrogen is either in the form of ammonia or nitric acid4 ,loss of ,ammonia4 ,ammonia1 when uncombined1 is a very volatile gas with a pungent smell1 a property which enables its escape from a manure mixture to be very easily detected4 ,it belongs to a class of substances which are known chemically as bases1 and which have the power of combining with acids and forming salts4 ,sulphate of ammonia is a salt formed--as its name indicates--by the union of the base1 ammonia1 with the acid1 sulphuric acid4 ,now when ammonia unites with sulphuric acid and forms sulphate of ammonia1 it is no longer volatile and liable to escape as a gas1 but becomes fixed1 as it is called4 ,although most salts are more or less stable bodies--not liable to change--if left alone1 and not submitted to a high temperature or chemical action1 they can be easily decomposed if they are heated or brought into contact with some other substance which will give rise to chemical action4 ,sulphate of ammonia is a salt that is very easily decomposed4 ,this is due to the fact that its base1 ammonia1 is very volatile1 and not capable of being held very firmly by an acid1 even by sulphuric1 which is among the least volatile of all the common acids4 ,if1 therefore1 sulphate of ammonia be heated above the boiling-point of water1 or brought in contact with any other substance which will give rise to chemical action1 it is easily decomposed4 ,now a salt may be acted upon by a base or an acid or another salt4 ,when it is brought in contact with a base1 if the base with which it is brought in contact be a stronger base than the base of the salt1 the salt is decomposed1 and a new salt is formed4 ,the acid1 in short1 exchanges its old base for the new one4 ,effect of ,lime on ,ammonia ,salt4 ,this is exactly what takes place when the base lime comes in contact with an ammonium salt1 such as sulphate of ammonia4 ,the sulphuric acid exchanges its old base1 ammonia1 for the stronger base1 lime1 and sulphate of lime is formed1 and ammonia is set free as a gas1 and escapes and is lost4 ,sulphate of ammonia1 or any substance in which there is an ammonia salt1 must never be brought in contact with free lime1 otherwise the ammonia will be lost1 and should be harrowed in on chalky soils for this reason4 ,it is different entirely with gypsum--which is sulphate of lime--or phosphate of lime1 both of which may be safely mixed with sulphate of ammonia without any danger of escape of ammonia4 ,it follows from the above that a mixture which must on no account be tried is slag phosphate and sulphate of ammonia4 ,this is because the slag phosphate contains a large percentage of free lime1 which would at once1 on being brought in contact with the sulphate of ammonia1 decompose it1 and cause the ammonia to be lost4 ,for this same reason guano must not be mixed with slag4 ,it is perhaps unnecessary1 however1 to warn one against so doing1 as it is not likely such a mixture would be made1 as the ratio of phosphoric acid to nitrogen in guanos is generally greater than is required4 ,if it be desired to mix the slag with a quickly available form of nitrogen1 nitrate of soda is not liable to loss2 although for other reasons it is not desirable to apply nitrate of soda along with the slag1 as the former manure should be applied almost always as a top-dressing4 ,loss of ,nitric ,acid4 ,the risks of the loss of nitrogen in the form of nitric acid1 although not so great as they are in the case of ammonia1 are still considerable4 ,as nitric acid is not a base but an acid1 what is to be avoided in mixing nitrates is bringing them in contact with any other manure which contains another free and stronger acid--as1 for example1 superphosphate4 ,the free acid present in superphosphate has the tendency to drive out the nitric acid from the nitrate and usurp its place4 ,the risk of loss of expulsion in the above cases is always augmented by the rise of temperature which invariably accompanies chemical action of any kind2 and although the loss of nitrogen1 in the form of nitric acid1 caused by mixing superphosphate and nitrate of soda1 might1 under ordinary circumstances1 amount to very little1 yet1 if the mixture were to be allowed to stand any time1 and the temperature of the mass to be heightened1 the loss which would undoubtedly then ensue would be considerable4 ,the nitrogen salt which it is safe to mix with superphosphate is sulphate of ammonia4 ,reversion of ,phosphates4 ,but1 as has already been mentioned1 there is another loss which may result from the mixing of manures4 ,this is the deterioration of the value of an ingredient by reason of change of chemical condition4 ,this is a source of loss that was little suspected a number of years ago1 but it is now well known that superphosphate of lime1 under certain conditions1 is changed from its soluble to an insoluble form4 ,we have already referred to the reversion of phosphate in the chapter on the ,manufacture of ,superphosphates4#bdg ,it was there pointed out that reversion is often caused by the presence of iron and alumina or undissolved phosphate1 and that the risk of reversion is therefore very much less in a well-made article1 made from pure raw material1 than in one made from a raw phosphate containing much iron and alumina4 ,superphosphates containing a large percentage of insoluble phosphates ought not to be kept too long before being used as a manure1 otherwise much of the labour and expense involved in their manufacture will be lost by the reversion of their soluble phosphate4 ,further1 it is highly inadvisable to mix superphosphates with basic slag1 which contains a large percentage of both iron and free lime4 ,lastly1 if it is desired to mix superphosphate with insoluble phosphate1 the mixture ought to be made just previous to application4 ,manurial ,ingredients should be applied separately4 ,the question of applying manure in mixtures is one on which considerable difference of opinion may exist4 ,for many reasons manures are often better applied in the unmixed condition4 ,for example1 a mixture of a quickly acting nitrogenous manure with a slowly acting phosphatic manure is not suitable4 ,in such a case either the nitrogenous manure will be applied too long before it is required by the plant1 and thus suffer from risk of loss1 or the phosphatic manure will not be applied long enough before it is likely to be used4 ,by applying manures in an unmixed condition the chances are that a more economical use of them is made than would otherwise be the case4 ,on the other hand1 while the application of the separate constituents may be desirable from the scientific point of view1 it involves a considerable amount of extra trouble4 ,of course a further consideration is the desirability in many cases of having a complete manure4 ,the above hints1 therefore1 on the risks of loss which exist in mixing manures1 may be of service to the agricultural student4 ,,footnotes3 #bdg ,see p4 #chi4 ,,chapter ,,xxv4 ,,on ,,the ,,valuation ,,and ,,analysis ,,of ,,manures4 ,value of ,chemical ,analysis4 ,the value of a manure to the farmer depends on the proportion of nitrogen1 phosphoric acid1 and potash it contains1 as well as--and this is hardly less important--the condition in which the ingredients are present4 ,since these facts can alone be determined by a chemical analysis1 it is obvious that manures should always be purchased with a chemical analysis4 ,it is unfortunate1 however1 that very often a chemical analysis1 even when procured1 is unintelligible4 ,it may be of advantage1 therefore1 to say a word or two on the correct interpretation of the significance of the data furnished in the ordinary chemical analysis of manures4 ,interpretation of ,chemical ,analysis4 ,the first thing that the farmer ought to look for in the analysis of a manure is the amount of nitrogen1 phosphoric acid1 and potash which the manure contains4 ,nitrogen4 ,the percentage of nitrogen in a manure is generally stated as equal to its equivalent percentage of ammonia4 ,very often1 indeed1 in the older analyses1 its equivalent of ammonia was alone stated4 ,now this statement does not necessarily imply that the nitrogen in a manure is actually present in the form of ammonia4 ,thus1 for example1 when it is stated in an analysis of bone-meal that it contains #c4e per cent of nitrogen1 equal to #d4bj per cent of ammonia1 it is not to be inferred that bone-meal actually contains nitrogen in the form of ammonia4 ,in point of fact the nitrogen is present in an insoluble1 slowly available1 organic form1 which possesses a manurial value very inferior to that possessed by ammonia4 ,this custom is a most unfortunate one1 and is much to be regretted1 as it is often liable to give rise to serious misunderstanding4 ,it must be remembered1 therefore1 that an ordinary chemical analysis does not always specify the exact form in which nitrogen is actually present4 ,it is nevertheless of importance for the farmer to know this1 of which the nature of the manure analysed is generally a good indication4 ,unfortunately this is not shown in the case of mixed manures2 and this constitutes one of the reasons why mixed manures are sometimes to be regarded with suspicion4 ,phosphoric ,acid4 ,the amount of phosphates present in a manure is usually stated in its analysis as so much phosphoric acid1 while in a footnote the quantity of tricalcic 7or ordinary bone7 phosphate this amount is equivalent to is also given1 this being the unit of valuation4 ,when the phosphates are in a soluble condition they are stated as such1 and at the same time a statement is made as to the quantity of tricalcic phosphate which would be required to furnish this amount by treatment with sulphuric acid4 ,thus1 for example1 in an analysis of a superphosphate of lime1 the statement1 monocalcic phosphate1 #ag4c per cent1 equal to tricalcic phosphate rendered soluble1 #bg4b per cent1 means that it would require #bg4b per cent of tricalcic phosphate to furnish #ag4c per cent of soluble phosphate4 ,paradoxically enough1 the former amount is called soluble phosphate1 and such a superphosphate as the above would be described as containing #bg4b per cent of soluble phosphate4 ,again1 there are different forms of the so-called insoluble phosphates1#bdh although they are often not distinguished in a chemical analysis4 ,as we have already pointed out in the chapter on ,basic ,slag1 phosphoric acid occurs in the slag in the form of tetrabasic phosphate of lime1 although it is invariably stated in analysis as so much tricalcic phosphate4 ,then we have the so-called dibasic phosphate of lime1 the form into which soluble phosphate in superphosphate is converted when reversion takes place4 ,hitherto it has not been customary in this country--although the custom is prevalent both on the ,continent and in ,america--to distinguish in the analysis of a superphosphate the reverted phosphate from the undissolved phosphate2 since the superior value of the former as a manure is not recognised in the manure-trade4#bdi ,importance of ,mechanical ,condition of ,phosphate4 ,a further point to which it is desirable to draw attention is the mechanical condition of the different insoluble phosphates1 which has an important influence on their value4 ,a very wide difference1 for example1 exists between the value of phosphate of lime in such a manure as ,malden guano and in the crystalline mineral apatite2 although1 chemically considered1 the form in which the phosphoric acid is present is the same in both substances4 ,potash4 ,potash ought only to occur in a soluble form in manures4 ,it is generally stated as so much potash1 and in a footnote the equivalent amount of muriate or sulphate of potash is given1 the former being the more concentrated form of potash4 ,for purposes of reference a table will be found in the ,appendix#bej giving some useful factors for converting different forms of nitrogen1 phosphoric acid1 and potash into one another4 ,other ,items in the ,chemical ,analysis of ,manures4 ,the other items in the analysis of a manure are of comparatively secondary importance compared with those already named4 ,among them may be mentioned the moisture1 the insoluble matter1 and the organic matter4 ,the amount of moisture and the amount of sand are two items of importance1 since1 if these are excessive1 they afford presumption that the manure has been adulterated4 ,fertilisers and ,feeding ,stuffs ,act4 ,an ,act was passed1 and came into operation in ,january #ahid1 for the purpose of compelling every vendor of manure manufactured in this country or imported from abroad to give to the purchaser an invoice stating the name of the article1 and whether it is an artificially compounded article or not1 and what is at least the percentage of the nitrogen1 soluble and insoluble phosphates1 and potash1 if any1 contained in the article1 and this invoice shall have the same effect as a warranty by the seller of the statements contained therein4 ,different ,methods of ,valuing ,manures4 ,the monetary value of a manure depends upon a number of more or less complicated commercial considerations1 such as the questions of supply and demand1 c41 which need not here be discussed1 and which similarly regulate the monetary value of any other article of commerce4 ,unit ,value of ,manurial ,ingredients4 ,for the purpose of affording data for ascertaining the approximate value of a manure1 tables have been drawn up giving what is called the unit value of the different manurial ingredients in various manures4 ,this is obtained by dividing the market value of a manure per ton by the percentage of nitrogen1 phosphoric acid1 and potash it contains4 ,thus1 for example1 sulphate of ammonia of #ig per cent purity contains #be per cent of ammonia1 and at present 7,dec4 #ahic7 is valued at ,l#ac1 #aes4 per ton4 ,in order to obtain the unit value of ammonia in sulphate of ammonia1 we have only to divide ,l#ac1 #aes4 by #be1 which gives us #aas4 ,the value of such tables depends on the competence of those drawing them up1 and they require to be subjected to constant revision4 ,in the ,appendix will be found two of these tables1 taken from the ',transactions of the ,highland and ,agricultural ,society of ,scotland4'#bea ,intrinsic ,value of ,manures4 ,but there is another way of valuing manures1 and that is by attempting to ascertain what their intrinsic worth is in producing an increase in the returns of the crops4 ,of course it may be said that the intrinsic worth of manure affects directly its market value4 ,this is doubtless true1 but it is not the only factor in determining the market value of a manure4 ,again1 the intrinsic worth of a manure may be said to vary according to the soil to which it is applied and the climatic conditions4 ,this being so1 it is important for every farmer to try and ascertain for himself what the intrinsic value of different manures is on the soil of his farm2 and this can only be done by carrying out manuring experiments for himself4 ,this leads us to say a word or two on the important subject of ,field ,experiments4 ,it is impossible that every farm should be able to support an experiment station for the purpose of carrying out elaborate experiments on the effect of different manures on different crops4 ,nevertheless it is possible and highly desirable for every farmer who is engaged in arable farming on any scale to carry out simple experiments for the purpose of ascertaining the characteristic manurial requirements of his soil4 ,this can be done at the expenditure of a little time and trouble1 and should be carried out in the following way4 ,the field on which it is desired to carry out the experiments should be divided into the requisite number of experiment plots4 ,these1 which may be the tenth1 twentieth1 or fortieth of an acre in extent1 should be1 if possible1 on a level piece of ground--all of them equally free from the shelter of hedge or tree1 and otherwise subjected to the same conditions4 ,the nature of the soil of the different plots1 as well as its past treatment1 should be similar4 ,it is desirable1 in order to minimise experimental error as much as possible1 to carry out the experiments in duplicate1 or even triplicate4 ,in the first place1 there should be what is called a nothing plot--i4e41 a plot receiving no manure4 ,the produce obtained from this plot1 compared with the produce obtained from the other manured plots1 will thus furnish data for estimating the respective amounts of increase obtained by different manures4 ,one very simple kind of experiment is what is called the seven-plot test4 ,it consists in testing the results obtained by using nitrogenous1 phosphatic1 and potash manures alone and in different combinations4 ,thus the plots would be manured respectively as follows3-- ,no4 ,no4 #a4 ,nothing plot4 #e4 ,nitrogen and phosphates4 #b4 ,nitrogen4 #f4 ,nitrogen and potash4 #c4 ,phosphates4 #g4 ,phosphates and potash4 #d4 ,potash4 ,the subjects of other experiments might be such as the respective values of nitrogen in the different forms of sulphate of ammonia and nitrate of soda2 phosphoric acid as superphosphate1 and in an undissolved form as ,thomas-slag2 the relative importance of artificial and farmyard manure2 the effect of manures applied at different times1 as well as the effect of different quantities of the same manure2 the most economical manures for different kinds of crops2 and numerous other interesting problems connected with the practical application of manures4 ,in carrying out these experiments1 care should be taken not to have the experimental plots immediately adjoining one another1 as the manure applied to the one plot may1 by soaking through the soil1 affect the result on the adjoining plot4 ,especial note ought to be taken of the weather during the progress of the experiment4 ,in order to make such experiments as valuable as possible1 they ought to be continued year after year4 ,at the conclusion of the experiment the produce obtained from each plot should be carefully weighed4 ,educational ,value of ,field ,experiments4 ,the educative value of such experiments is very great1 and in this connection the remarks made by ,mr ,f4 ,j4 ,cooke1 in a recent lecture delivered to the ,london ,farmers' ,club1 are worthy of most careful consideration4 ,local experiments1 he says1 teach the simple principles which should determine the selection of manures1 as well as scientific accuracy and method in their use4 ,the value of experiments is thus brought home to men who would not go far to discover it2 and the practice of a few simple trials upon a correct system1 each on his own farm1 is encouraged4 ,that such trials may be conducted with very little expense to the farmer1 or other difficult qualifications1 and yet to his great practical advantage1 ,i will venture to assert on the ground of my own personal experience4 ,for some twenty years ,i have annually conducted private experiments on a very humble scale1 and am not aware of any other separate practice which has been so useful to me4 ,it has been pursued upon two light-land farms in different parts of the same county4 ,yet1 in respect of manurial requirements1 the proper treatment for one of them has differed so essentially from the other that a common practice upon both would have been simply ruinous4 ,value of ,manures deduced from ,experiments4 ,tables have been constructed for the purpose of showing the comparative value of different kinds of manures as deduced from such experiments1 and may be fittingly compared with the tables giving the trade prices4 ,we have already quoted some of these tables in the ,appendix to the chapter on ,mineral ,phosphates4 ,these tables show the relative intrinsic value of different forms of phosphatic manures4 ,in the ,appendix#beb to this chapter tables showing the relative value of different kinds of nitrogenous and potash manures will be found4 ,value of ,unexhausted ,manures4 ,a subject which has had much attention devoted to it of late years is the question of the value of unexhausted manures in the soil4 ,in the ,agricultural ,holdings ,act special provision is made for giving compensation to the out-going tenant of a farm for unexhausted manures in the soil4 ,the ,act has given rise to endless disputes between landlord and tenant1 owing to the extreme difficulty of arriving at a satisfactory estimate of what the value of the unexhausted manures in reality is4 ,the difficulty arises from the fact that we have not sufficient data available for guiding us in estimating this value1 which further varies under different conditions4 ,the fertilising ingredients of a soil are present in the soil for the most part in an inert condition1 from which they are only slowly converted into an available form4 ,potential ,fertility of a ,soil4 ,as indicating the total amount of the more important mineral ingredients present in a soil1 it may be mentioned that it has been calculated1 in the case of a poor sandy soil1 that the amount of potash it contains 7provided it were in an available condition7 would be sufficient to yield three or four average crops of potatoes2 of phosphates1 nineteen average crops2 and of lime1 seventy-three4 ,but then only a very small amount of this fertilising matter is in a readily available form4 ,it is for this reason that artificial manures1 although added in such small amounts1 exercise so striking an influence in increasing plants' growth4 ,their effect1 however1 is to a large extent only of a temporary nature2 and in attempting to assess the unexhausted value of a manure a year or two after its application1 we must remember this fact4 ,some manures are very speedily taken up by plants1 and some are very easily washed out of the soil4 ,others1 again1 it would seem highly probable1 have a tendency to become converted into a more or less inert condition after a while4 ,this remark may be especially applied to the fertilising constituents 7chiefly nitrogen7 in farmyard manure4#bec ,the whole question1 however1 is little understood4 ,one or two points may be drawn attention to4 ,in the first place1 it may be safely affirmed that little direct effect can be expected from such quickly available and easily soluble forms of nitrogenous manures as nitrate of soda and sulphate of ammonia a year after application4 ,potash and phosphates1 on the other hand1 may exercise an effect for a considerably longer period2 and what the length of this period may be will depend on their amount and condition4 ,thus it is not likely that superphosphate will have much effect more than two years after application4 ,on the other hand1 such manures as bones1 basic slag1 and farmyard manure may exert an appreciable influence for a number of years4 ,how long exactly1 it is wellnigh impossible to say1 the rate at which they are applied and the nature of the soil having an important influence4 ,tables of ,value of ,unexhausted ,manures4 ,numerous tables have been drawn up for the purpose of guiding farmers in estimating this unexhausted value at different periods after application1 and in the case of different manures4 ,such tables1 as a rule1 furnish only very rough approximations1 and are little better than mere guess-work4 ,still more complicated is the attempt to assess the manurial value of foods consumed by the stock of the farm4 ,lawes and ,gilbert have devoted much attention to the elucidation of this difficult question1 and have drawn up most elaborate and valuable tables1 furnishing data for calculating unexhausted manure value in the case of commonly used foods4 ,these tables are given in the ,appendix4#bed ,in them will be found the manurial value of different cattle-foods1 calculated on the basis of numerous experiments carried out at ,rothamsted4 ,thus these experiments have demonstrated that1 on an average1 probably not more than one-tenth of the nitrogen1 phosphoric acid1 and potash a food contains is removed from the food in its passage through the animal system4 ,the exact amount will obviously depend on a variety of conditions1 referred to already in a previous chapter4#bee ,in explanation of these tables1 it may be pointed out that ,table ,i4 gives the total quantities of the three fertilising ingredients in various foods2 while ,table ,,ii4 shows the proportion retained in the animal body and the proportion voided in the manure1 as well as the manurial value of the food1 assuming that it exercises its full theoretical effect4 ,as this1 however1 is never fully realised1 it is necessary to make some deduction4 ,the deduction suggested by the ,rothamsted experimenters1 on the basis of their wide experience1 is #ej per cent for food consumed within the last year4 ,that is to say1 the manurial value of food consumed during the last year is only one-half its theoretical value4 ,for food consumed within the last year but one1 they suggest a deduction of one-third of the allowance for last year2 while for food consumed three years back1 a deduction of one-third from this latter sum should be made2 and so on for whatever number of years1 down to eight1 may be taken4 ,,footnotes3 #bdh ,the term insoluble phosphates is an unfortunate one1 as the word insoluble is purely relative in its significance4 ,undissolved phosphates would be a better term4 #bdi ,the amount of reverted phosphate is estimated by the ammonium citrate process4 #bej ,see ,note ,i41 p4 #eec4 #bea ,see ,note ,,ii41 p4 #eed4 #beb ,see ,note ,,iii41 p4 #eef4 #bec ,see ,chapter on ,farmyard ,manure1 p4 #bga4 #bed ,see ,note ,,iv41 p4 #eeg4 #bee ,see ,chapter on ,farmyard ,manure1 pp4 #bbd-bcf4 ,,appendix ,,to ,,chapter ,,xxv4 ,,note ,i4 7p4 #edc74 ,,useful ,,factors ,,for ,,calculating ,,the ,,percentage ,,of ,,important ,,manurial ,,ingredients ,,in ,a ,,manure ,,into ,,their ,,different ,,compounds4 7,from the ',transactions of the ,highland and ,agricultural ,society4'7 ---------------------------------------- ---------------------- ,multiplied ,gives corresponding ,amount of by amount of ---------------------------------------- ---------------------- ,nitrogen #a4bad ,ammonia4 #f4c ,albuminoid matter4 ,ammonia 4#hbd ,nitrogen4 #c4hhb ,sulphate of ammonia4 #c4adg ,muriate of ammonia4 #c4gjf ,nitric acid4 #e4j ,nitrate of soda4 ,potash 7anhydrous7 #a4he ,sulphate of potash4 #a4ehe ,muriate of potash4 ,phosphoric acid 7anhydrous7 #b4ahc ,phosphate of lime4 #a4d ,biphosphate4 #a4fdh ,soluble phosphate4 ,soluble phosphate #a4cbe ,phosphate of lime4 ,biphosphate #a4eff ,lime #a4hde #a4ghf ,carbonate of lime4 ,chlorine #a4fdh ,chloride of sodium4 ---------------------------------------- ---------------------- ,,notes ,,ii4 7p4 #ede74 ,,units ,,to ,,be ,,used ,,in ,,determining ,,the ,,commercial ,,value ,,of ,,manures4 ,for ,season #ahic4 ,a3 ,ichaboe4 ,b3 ,peruvian 7riddled74 ,c3 ,fish guano4 ,d3 ,frey ,bentos guano4 ,e3 ,steamed bone-flour4 ,f3 ,dissolved or vitriolated bones4 ,g3 ,superphosphates4 ,h3 ,genuine4 ,i3 ,genuine4 ,j3 ,average4 ---------------------------------------- ---------------- ,guanos4 ,scrap manures4 ,items to be -------------------------- ,bone-meal4 valued4 ,a ,b ,c ,d ---------------------------------------- ------------ ,classes ,h ,i a4 b4 a4 b4 ---------------------------------------- ------------ ,phosphates ,dissolved - - - - - - - ,undissolved-- #b_/- #b_/- #a_/e #a_/f #a_/d #a_/d #a_/c ,ammonia #af_/- #ag_/f #aj_/- #aa_/f #aj_/- #aj_/- #i_/f ,potash - #c_/f - - - - - ,prices per ton1 ,march #ahic-- ,from #bej_/-bcj_/-acj_/-aej_/-abj_/-aje_/-ajj _/- ,to #bgj_/-bij_/-aej_/-ahj_/-adj_/-aae_/-aaj _/- ---------------------------------------- ------------ ---------------------------------------- --------- ,items to be ,e ,f ,g ,dissolved valued4 ,compounds4 ---------------------------------------- ------- ,classes a4 ,from ,to ,j ---------------------------------------- ------- ,phosphates ,dissolved - #b_/f - #b_/- #b_/f #b_/c ,undissolved-- #a_/e #a_/f #a_/aa #a_/c #a_/i #a_/f ,ammonia #aj_/- #aa_/f - #aj_/- #ab_/- #aa_/- ,potash - - - #c_/d #c_/h #c_/f ,prices per ton1 ,march #ahic-- ,from #ie_/- #ie_/- #de_/- - - - ,to #aaj_/-aaj_/- #fj_/- - - - ---------------------------------------- ------- ,,cash ,,prices ,,of ,,different ,,manures1 ,,march #ahic4 ---------------------------------------- ---------------------------- ,price per ,,manures4 ,guarantee4 ton4 ,unit4 ---------------------------------------- ---------------------------- ,per cent4 ,l s4 d4 ,sulphate of ammonia1 #ig per cent #bd ,am4 #aa #aj #j ,am4 #i_/g ,nitrate of soda1 #ie per cent #ai #aj #e #j #aj_/i ,castor-cake dust #e4e #c #aj #j #ab_/i ,horn-dust #ae #h #aj #j #aa_/d ,dried blood #ae #h #j #j #aj_/g ,muriate of potash1 #hj per cent #ej ,pot #h #ae #j ,pot4 #c_/f ,sulphate of potash1 #ej per cent #bg #e #e #j #c_/aj ,kainit1 #bc per cent #ab #b #j #j #c_/d ,nitrate of potash1 #gc per cent #ad ,am4 #ad #aj #j ,am4 #aj_/ #dj ,pot4 ,pot4 #c_/i ,ground ,charleston phosphate #eg ,phos4 #c #j #j ,phos4#a_/ ,belgian phosphate #ej #b #e #j #j_/aa ,thomas-slag 7fine7 ,scotch #cj #a #af #j #a_/b ,thomas-slag 7fine7 ,english #cg #b #c #j #a_/b ,phosphatic guano #fg #e #j #j #a_/d #a ,am4 ,am4 #aj_/ ---------------------------------------- ---------------------------- ,,note ,,iii4 7p4 #edi74 ,,tables ,,showing ,,relative ,,manurial ,,value ,,of ,,nitrogen ,,and ,,potash ,,in ,,different ,,substances4 ,wolff1 #ahic4 ,nitrogen in form of ammonia and nitrates1 and easily decomposable organic compounds1 as dried blood1 flesh-meal1 meat-meal1 ,peruvian guano1 and as urate #ajj in fine steamed bone-meal1 fish-guano1 oilcakes1 and better kinds of artificial guano #he in fine bone-meal and horn-meal #gg in coarse bones and horn-shavings1 woollen refuse1 farmyard manure1 and poudrette #fa ,american1 #ahib4 in ammonia salts #ajj as nitrates #hf in dry and fine-ground fish1 meat1 and blood #ia in cotton-seed meal1 and castor pomace #hf in fine bone and tankage #hf in medium bone and tankage #fh in coarser bone and tankage #dc in hair and horn-shavings1 and coarse fish scrap #dj ,potash as high-grade sulphate1 and in forms free from muriates 7or chlorides7 #ajj as muriate #hb ,professor ,wagner has drawn up1 from numerous experiments1 the relative manurial values of different nitrogenous manures1 which he rates as follows3-- ,nitrate of soda #ajj ,sulphate of ammonia #ij ,blood-meal1 horn-meal1 and green vegetable matter #gj ,finely ground steamed bone-meal1 fish-meal1 and meat-meal guano #fj ,farmyard manure #de ,shoddy #cj ,leather-meal #bj ,,note ,,iv4 7p4 #eea74 ,,table ,i4--,,average ,,composition1 ,,per ,,cent ,,and ,,per ,,ton1 ,,of ,,cattle-,,foods4 ---------------------------------------- ------------------------------- ,,per ,,cent4 ,,no4 ,,foods4 ---------------------------------------- --- ,dry ,nitro- ,mineral ,phos- ,potash4 ,matter4 gen4 ,matter phoric 7,ash74 ,acid ---------------------------------------- --------------------------- per per per per per cent4 cent4 cent4 cent4 cent4 #a ,linseed #ij4jj #c4fj #d4jj #a4ed #a4cg #b ,linseed-cake #hh4ej #d4ge #f4ej #b4jj #a4dj #c ,decorticated cotton cake #ij4jj #f4fj #g4jj #c4aj #b4jj #d ,palm-nut-cake #ia4jj #b4ej #c4fj #a4bj #j4ej #e ,undecorticated cotton-cake #hg4jj #c4ge #f4jj #b4jj #b4jj #f ,cocoa-nut-cake #ij4jj #c4dj #f4jj #a4dj #b4jj #g ,rape-cake #hi4jj #d4ij #g4ej #b4ej #a4ej ---------------------------------------- --------------------------- #h ,peas #he4jj #c4fj #b4ej #j4he #j4if #i ,beans #he4jj #d4jj #c4jj #a4aj #a4cj #aj ,lentils #hh4jj #d4bj #d4jj #j4ge #j4gj #aa ,tares 7seed7 #hd4jj #d4bj #b4ej #j4hj #j4hj ---------------------------------------- --------------------------- #ab ,indian corn #hh4jj #a4gj #a4dj #j4fj #j4cg #ac ,wheat #he4jj #a4hj #a4gj #j4he #j4ec #ad ,malt #id4jj #a4gj #b4ej #j4hj #j4ej #ae ,barley #hd4jj #a4fe #b4bj #j4ge #j4ee #af ,oats #hf4jj #b4jj #b4hj #j4fj #j4ej #ag ,rice-meal99 #ij4jj #a4ij #g4ej 7#j4fj7 7#j4cg7 #ah ,locust-beans99 #he4jj #a4bj #b4ej - - ---------------------------------------- --------------------------- #ai ,malt-combs #ij4jj #c4ij #h4jj #b4jj #b4jj #bj ,fine pollard #hf4jj #b4de #e4ej #b4ij #a4df #ba ,coarse pollard #hf4jj #b4ej #f4dj #c4ej #a4ej #bb ,bran #hf4jj #b4ej #f4ej #c4fj #a4de ---------------------------------------- --------------------------- #bc ,clover-hay #hc4jj #b4dj #g4jj #j4eg #a4ej #bd ,meadow-hay #hd4jj #a4ej #f4ej #j4dj #a4fj ---------------------------------------- --------------------------- #be ,pea-straw #hb4ej #a4jj #e4ej #j4ce #a4jj #bf ,oat-straw #hc4jj #j4ej #e4ej #j4bd #a4jj #bg ,wheat-straw #hd4jj #j4de #e4jj #j4bd #j4hj #bh ,barley-straw #he4jj #j4dj #d4ej #j4ah #a4jj #bi ,bean-straw #hb4ej #j4ij #e4jj #j4cj #a4jj ---------------------------------------- --------------------------- #cj ,potatoes #be4jj #j4be #a4jj #j4ae #j4ee #ca ,carrots #ad4jj #j4bj #j4ij #j4ji #j4bh #cb ,parsnips #af4jj #j4bb #a4jj #j4ai #j4cf #cc ,swedish turnips #aa4jj #j4be #j4fj #j4jf #j4bb #cd ,mangel-wurzels #ab4ej #j4bb #a4jj #j4jg #j4dj #ce ,yellow turnips99 #i4jj #j4bj #j4fe 7#j4jf7 7#j4bb7 #cf ,white turnips #h4jj #j4ah #j4fh #j4je #j4cj ---------------------------------------- --------------------------- ---------------------------------------- --------------- ,,per ,,ton4 ----------------------------- ,,no4 ,,foods4 ,nitrogen4 ,phos- ,potash4 phoric ,acid ---------------------------------------- ------------- lb4 lb4 lb4 #a ,linseed #hj4fd #cd4ej #cj4fi #b ,linseed-cake #ajf4dj #dd4hj #ca4cf #c ,decorticated cotton cake #adg4hd #fi4dd #dd4hj #d ,palm-nut-cake #ef4jj #bf4hh #aa4bj #e ,undecorticated cotton-cake #hd4jj #dd4hj #dd4hj #f ,cocoa-nut-cake #gf4af #ca4cf #dd4hj #g ,rape-cake #aji4gf #ef4jj #cc4fj ---------------------------------------- ------------- #h ,peas #hj4fd #ai4jd #ba4ej #i ,beans #hi4fj #bd4fd #bi4ab #aj ,lentils #id4jh #af4hj #ae4fh #aa ,tares 7seed7 #id4jh #ag4ib #ag4ib ---------------------------------------- ------------- #ab ,indian corn #ch4jh #ac4dd #h4bi #ac ,wheat #dj4cb #ai4jd #aa4hg #ad ,malt #ch4jh #ag4ib #aa4bj #ae ,barley #cf4if #af4hj #ab4cb #af ,oats #dd4hj #ac4dd #aa4bj #ag ,rice-meal99 #db4ef 7#ac4dd7 7#h4bi7 #ah ,locust-beans99 #bf4hh - - ---------------------------------------- ------------- #ai ,malt-combs #hg4cf #dd4hj #dd4hj #bj ,fine pollard #ed4hh #fd4if #cb4gj #ba ,coarse pollard #ef4jj #gh4dj #cc4fj #bb ,bran #ef4jj #hj4fd #cb4dh ---------------------------------------- ------------- #bc ,clover-hay #ec4gf #ab4gg #cc4fj #bd ,meadow-hay #cc4fj #h4if #ce4hd ---------------------------------------- ------------- #be ,pea-straw #bb4dj #g4hd #bb4dj #bf ,oat-straw #aa4bj #e4ch #bb4dj #bg ,wheat-straw #aj4jh #e4ch #ag4ib #bh ,barley-straw #h4if #d4jc #bb4dj #bi ,bean-straw #bj4af #f4gb #bb4dj ---------------------------------------- ------------- #cj ,potatoes #e4fj #c4cf #ab4cb #ca ,carrots #d4dh #b4jb #f4bg #cb ,parsnips #d4ic #d4bf #h4jf #cc ,swedish turnips #e4fj #a4cd #d4ic #cd ,mangel-wurzels #d4ic #a4eg #h4if #ce ,yellow turnips99 #d4dh 7#a4cd7 7#d4ic7 #cf ,white turnips #d4jc #a4ab #f4gb ---------------------------------------- ------------- 99 ,in the case of neither rice-meal1 locust-beans1 nor yellow turnips have records of ash analyses been found4 ,for rice-meal the same percentages of phosphoric acid and potash as in ,indian corn1 and for yellow turnips the same as in swedes1 are provisionally adopted2 but in all the ,tables the assumed results are given in parentheses4 ,for locust-beans no figure has been assumed1 and the columns are left blank4 ,,note ,,iv4 ,,table ,,ii4--,,lawes' ,,gilbert',s ,,tables ,,for ,,calculating ,,unexhausted ,,value ,,of ,,manures4 ,,key3 ,a - ,fattening ,increase in ,live ,weight 7,oxen or ,sheep74 ,b - ,in ,food4 ,c - ,in ,fattening ,increase 7at #a4bg per cent74 ,d - ,in ,manure4 ,e - ,food to #a ,increase4 ,f - ,increase per ton of ,food4 ,g - ,per cent4 ,h - ,per ton4 ,i - ,from #a ton of ,food4 ,j - ,per cent of total consumed4 ,k - ,total remaining for ,manure4 ,l - ,nitrogen equal ,ammonia4 ,m - ,value of ,ammonia at #f;d per lb4 ---------------------------------------- ----------------------------------- ,,nitrogen4 ---------------------------------------- ---- ,a ,b ,c ,d ,,description ---------------------------------------- ---------- ,,no4 ,,of ,,food4 ,e ,f ,g ,h ,i ,j ,k ,l ,m ---------------------------------------- ---------------------------- lb4 lb4 lb4 lb4 lb4 ,l s4 d4 #a ,linseed #e4jddh4j #c4fj #hj4fd #e4fi #g4jf #gd4ie #ia4jb #e #f #b ,linseed-cake #f4jcgc4c #d4geajf4dj #d4gd #d4deaja4ffabc4dc #a #h #c ,decorticated cotton-cake #f4ecdd4f #f4fjadg4hd #d4ch #b4ifadc4dfagd4bd #g #a #d ,palm-nut-cake #g4jcbj4j #b4ej #ef4jj #d4jf #g4be #ea4id #fc4aa #aa #g #e ,undecorticated cotton-cake #h4jbhj4j #c4ge #hd4jj #c4ef #d4bd #hj4dd #ig4gb #h #aj #f ,cocoa-nut-cake #h4jbhj4j #c4dj #gf4af #c4ef #d4fg #gb4fj #hh4bb #d #a #g ,rape-cake 7#aj7 7#bbd7 #d4ijaji4gf #b4hd #b4eiajf4ibabi4hc #d #aa ---------------------------------------- ---------- #h ,peas #g4jcbj4j #c4fj #hj4fd #d4jf #e4jc #gf4eh #ic4jb #f #f #i ,beans #g4jcbj4j #d4jj #hi4fj #d4jf #d4ec #he4edajc4ib #aa #aa #aj ,lentils #g4jcbj4j #d4bj #id4jh #d4jf #d4cb #ij4jbaji4cb #ad #h #aa ,tares 7seed7 #g4jcbj4j #d4bj #id4jh #d4jf #d4cb #ij4jbaji4cb #ad #h ---------------------------------------- ---------- #ab ,indian corn #g4bcaa4a #a4gj #ch4jh #c4ieaj4cg #cd4ac #da4da #j #i #ac ,wheat #g4bcaa4a #a4hj #dj4cb #c4ie #i4hj #cf4cg #dd4ba #b #a #ad ,malt #g4jcbj4j #a4gj #ch4jh #d4jfaj4ff #cd4jb #da4ca #j #h #ae ,barley #g4bcaa4a #a4fe #cf4if #c4ieaj4fi #cc4ja #dj4aa #j #a #af ,oats #g4ebih4g #b4jj #dd4hj #c4gi #h4df #da4ja #di4ha #d #aa #ag ,rice-meal #g4ebih4g #a4ij #db4ef #c4gi #h4ia #ch4gg #dg4aa #c #f #ah ,locust-beans #i4jbdh4i #a4bj #bf4hh #c4afaa4gf #bc4gb #bh4hj #ad #e ---------------------------------------- ---------- #ai ,malt-combs #h4jbhj4j #c4ij #hg4cf #c4ef #d4jh #hc4hjaja4hb #aj #aa #bj ,fine pollard #g4ebih4g #b4de #ed4hh #c4gi #f4ia #ea4ji #fb4ja #aa #j #ba ,coarse pollard #h4jbhj4j #b4ej #ef4jj #c4ef #f4ce #eb4dd #fc4ga #aa #aj #bb ,bran #i4jbdh4i #b4ej #ef4jj #c4af #e4fd #eb4hd #fd4ba #ab #a ---------------------------------------- ---------- #bc ,clover-hay #ad4jafj4j #b4dj #ec4gf #b4jc #c4gh #ea4gc #fb4ha #aa #e #bd ,meadow-hay #ae4jadi4c #a4ej #cc4fj #a4ij #e4fe #ca4gj #ch4ej #ai #c ---------------------------------------- ---------- #be ,pea-straw #af4jadj4j #a4jj #bb4dj #a4gh #g4ie #bj4fb #be4jj #ab #f #bf ,oat-straw #ah4jabd4d #j4ej #aa4bj #a4ehad4aa #i4fb #aa4gj #e #aj #bg ,wheat-straw #ba4jajf4g #j4de #aj4jh #a4cfac4di #h4gb #aj4fj #e #d #bh ,barley-straw #bc4j #ig4d #j4dj #h4if #a4bdac4hd #g4gb #i4dj #d #h #bi ,bean-straw #bb4jaja4h #j4ij #bj4af #a4bi #f4ci #ah4hg #bb4ij #aa #f ---------------------------------------- --------- #cj ,potatoes #fj4j #cg4c #j4be #e4fj #j4dg #h4ci #e4ac #f4bj #c #a #ca ,carrots #he4g #bf4a #j4bj #d4dh #j4cc #g4cg #d4ae #e4jj #b #f #cb ,parsnips #ge4j #bi4i #j4bb #d4ic #j4ch #g4ga #d4ee #e4ej #b #i #cc ,swedish turnips#aji4a #bj4e #j4be #e4fj #j4bf #d4fd #e4cd #f4ej #c #c #cd ,mangel-wurzels #if4j #bc4c #j4bb #d4ic #j4cj #f4ji #d4fc #e4fj #b #aj #ce ,yellow turnips #acc4c #af4h #j4bj #d4dh #j4ba #d4fi #d4bg #e4bj #b #g #cf ,white turnips #aej4j #ad4i #j4ah #d4jc #j4ai #d4ga #c4hd #d4gj #b #d ---------------------------------------- ---------------------------- ,,key3 ,n - ,in ,food4 ,o - ,in ,fattening ,increase at 7#j4hf per cent74 ,p - ,in ,manure4 ,q - ,in ,food4 ,r - ,in ,fattening ,increase at 7#j4aa per cent74 ,s - ,in ,manure4 ,t - ,per cent4 ,u - ,per ton4 ,v - ,from #a ton of ,food4 ,w - ,per cent of total consumed4 ,x - ,total remaining for ,manure4 ,y - ,value at #c;d per lb4 ,z - ,per cent4 ,,aa - ,per ton4 ,,bb - ,from #a ton of ,food4 ,,cc - ,per cent of total consumed4 ,,dd - ,total remaining for ,manure4 ,,ee - ,value at #b-a_/b;d4 per lb4 ,,ff - ,total original ,manure value per ton of ,food consumed4 ---------------------------------------- -------------------- ,,phosphoric ,,acid4 ---------------------------------------- --------------- ,n ,o ,p ,description ------------------------------------- ,no4 of ,food4 ,t ,u ,v ,w ,x ,y ---------------------------------------- --------------- lb4 lb4 lb4 s4 d4 #a ,linseed #a4ed #cd4ej #c4he #aa4af #cj4fe #g #h #b ,linseed-cake #b4jj #dd4hj #c4ba #g4ag #da4ei #aj #e #c ,decorticated cotton-cake #c4aj #fi4dd #b4if #d4bf #ff4dh #af #h #d ,palm-nut-cake #a4bj #bf4hh #b4ge #aj4bc #bd4ac #f #j #e ,undecorticated cotton-cake #b4jj #dd4hj #b4da #e4ch #db4ci #aj #g #f ,cocoa-nut-cake #a4dj #ca4cf #b4da #g4fh #bh4ie #g #c #g ,rape-cake #b4ej #ef4jj #a4ic #c4de #ed4jg #ac #f ---------------------------------- -- #h ,peas #j4he #ai4jd #b4ge #ad4dd #af4bi #d #a #i ,beans #a4aj #bd4fd #b4ge #aa4aj #ba4hi #e #f #aj ,lentils #j4ge #af4hj #b4ge #af4cg #ad4je #c #f #aa ,tares 7seed7 #j4hj #ag4ib #b4ge #ae4cf #ae4ag #c #i ---------------------------------- -- #ab ,indian corn #j4fj #ac4dd #b4fh #ai4id #aj4gf #b #h #ac ,wheat #i4he #ai4jd #b4fh #ad4jh #af4cf #d #a #ad ,malt #j4hj #ag4ib #b4ge #ae4ce #ae4ag #c #i #ae ,barley #j4ge #af4hj #b4fh #ae4ie #ad4ab #c #f #af ,oats #j4fj #ac4dd #b4eg7ai4ab7 #aj4hg #b #h #ag ,rice-meal 7#j4fj77ac4dd7b4eg7ai4ab77aj4hg77b #h7 #ah ,locust-beans - - #b4ad - - - ------------------------------------- #ai ,malt-combs #b4jj #dd4hj #b4da #e4ch #db4ci #aj #g #bj ,fine pollard #b4ij #fd4if #b4eg #c4if #fb4ci #ae #g #ba ,coarse pollard #c4ej #gh4dj #b4da #c4jg #ge4ii #ai #j #bb ,bran #c4fj #hj4fd #b4ad #b4fe #gh4ej #ai #h ------------------------------------- #bc ,clover-hay #j4eg #ab4gg #a4ch #aj4ha #aa4ci #b #aj #bd ,meadow-hay #j4dj #h4if #a4bh #ad4bh #g4fh #a #aa ------------------------------------- #be ,pea-straw #j4ce #g4hd #a4bj #ae4ca #f4fd #a #h #bf ,oat-straw #j4bd #e4ch #a4jg #ai4hi #d4ca #a #a #bg ,wheat-straw #j4bd #e4ch #j4ib #ag4aj #d4df #a #a #bh ,barley-straw #j4ah #d4jc #j4hd #bj4hd #c4ai #j #i #bi ,bean-straw #j4cj #f4gb #j4hh #ac4aj #e4hd #a #e ------------------------------------- #cj ,potatoes #j4ae #c4cf #j4cb #i4eb #c4jd #j #i #ca ,carrots #j4ji #b4jb #j4bb #aj4hi #a4hj #j #e #cb ,parsnips #j4ai #d4bf #j4bf #f4aj #d4jj #a #j #cc ,swedish turnips #j4jf #a4cd #j4ah #ac4dc #a4af #j #d #cd ,mangel-wurzels #j4jg #a4eg #j4bj #ab4gd #a4cg #j #d #ce ,yellow turnips 7#j4jf7 7#a4cd7j4ad7aj4gh7 7#a4bj77j #d7 #cf ,white turnips #j4je #a4ab #j4ac #aa4fa #j4ii #j #c ---------------------------------------- --------------- ---------------------------------------- -------------------------- ,,potash4 ---------------------------------------- ------------- ,q ,r ,s ,description ---------------------------------- ,no4 of ,food4 ,z ,,aa ,,bb ,,cc ,,dd ,,ee ,,ff ---------------------------------------- --------------------- lb4 lb4 lb4 s4 d4 ,l s4 d4 #a ,linseed #a4cg #cj4fi #j4di #a4fj #cj4bj #f #c #b #ai #e #b ,linseed-cake #a4dj #ca4cf #j4da #a4ca #cj4ie #f #e #c #ah #f #c ,decorticated cotton-cake #b4jj #dd4hj #j4ch #j4he #dd4db #i #c #e #ac #j #d ,palm-nut-cake #j4ej #aa4bj #j4ce #c4ac #aj4he #b #c #a #ai #aj #e ,undecorticated cotton-cake #b4jj #dd4hj #j4ca #j4fi #dd4di #e #aa #c #e #d #f ,cocoa-nut-cake #b4jj #dd4hj #j4ca #j4fi #dd4di #i #c #c #j #g #g ,rape-cake #a4ej #cc4fj #j4be #j4gd #cc4ce #f #aa #d #e #d ---------------------------------------- --- #h ,peas #j4if #ba4ej #j4ce #a4fc #ba4ae #d #e #b #ae #j #i ,beans #a4cj #bi4ab #j4ce #a4bj #bh4gg #f #j #c #c #e #aj ,lentils #j4gj #ae4fh #j4ce #b4bc #ae4cc #c #b #c #a #d #aa ,tares 7seed7 #j4hj #ag4ib #j4ce #a4ie #ag4eg #c #h #c #b #a ---------------------------------------- --- #ab ,indian corn #j4cg #h4bi #j4cd #d4aj #g4ie #a #h #a #e #a #ac ,wheat #j4ec #aa4hg #j4cd #b4hf #aa4ec #b #e #a #h #g #ad ,malt #j4ej #aa4bj #j4ce #c4ac #aj4he #b #c #a #f #h #ae ,barley #j4ee #ab4cb #j4cd #b4gf #aa4ih #b #f #a #f #a #af ,oats #j4ej #aa4bj #j4cc #b4id #aj4hg #b #c #a #i #aj #ag ,rice-meal 7#j4cg77h4bi7j4cc7d4jj77g4if77a #h77a #g #aj7 #ah ,locust-beans - - #j4bg - - - - ---------------------------------------- --- #ai ,malt-combs #b4jj #dd4hj #j4ca #j4fi #dd4di #i #c #c #aj #i #bj ,fine pollard #a4df #cb4gj #j4cc #a4ja #cb4cg #f #i #b #ac #d #ba ,coarse pollard #a4ej #cc4fj #j4ca #j4ib #cc4bi #f #aa #b #ag #i #bb ,bran #a4de #cb4dh #j4bg #j4hc #cb4ba #f #h #b #ah #e ---------------------------------------- --- #bc ,clover-hay #a4ej #cc4fj #j4ah #j4ed #cc4db #g #j #b #a #c #bd ,meadow-hay #a4fj #ce4hd #j4af #j4de #ce4fh #g #e #a #h #g ---------------------------------------- --- #be ,pea-straw #a4jj #bb4dj #j4ae #j4fg #bb4be #d #h #j #ah #aj #bf ,oat-straw #a4jj #bb4dj #j4ad #j4fc #bb4bf #d #h #j #aa #g #bg ,wheat-straw #j4hj #ag4ib #j4ab #j4fg #ag4hj #c #h #j #aj #a #bh ,barley-straw #a4jj #bb4dj #j4aa #j4di #bb4bi #d #h #j #aj #a #bi ,bean-straw #a4jj #bb4dj #j4aa #j4di #bb4bi #d #h #j #ag #g ---------------------------------------- --- #cj ,potatoes #j4ee #ab4cb #j4jd #j4cb #ab4bh #b #g #j #f #e #ca ,carrots #j4bh #f4bg #j4jc #j4dh #f4bd #a #d #j #d #c #cb ,parsnips #j4cf #h4jf #j4jc #j4cg #h4jc #a #h #j #e #e #cc ,swedish turnips #j4bb #d4ic #j4jb #j4da #d4ia #a #j #j #d #g #cd ,mangel-wurzels #j4dj #h4ij #j4jc #j4cd #h4ic #a #aj #j #e #j #ce ,yellow turnips 7#j4bb77d4ic7j4jb7j4cd77d4ia77a #j77j #c #aa7 #cf ,white turnips #j4cj #f4gb #j4jb #j4cj #f4gj #a #e #j #d #j ---------------------------------------- --------------------- ,,chapter ,,xxvi ,,the ,,rothamsted ,,experiments4 ,reference has been so repeatedly made in the preceding pages to the ,rothamsted experiments on manures1 that it may form a fitting conclusion to the present treatise to give a short account of these famous experiments4 ,in describing these experiments1 the author has remarked elsewhere#bef that1 in respect of their wide scope1 dealing as they have done with almost every department of farming1 the elaborate care and accuracy with which they have been carried out1 the length of time they have been in progress1 and1 lastly1 in respect of the important bearing their results have had on agricultural practice1 these famous experiments may be justly described as unrivalled by any other similar ones4 ,started on a small scale in #ahcg by ,sir ,john 7then ,mr7 ,lawes1 they were placed on a systematic basis in #ahdc1 in which year ,sir ,john ,lawes associated with himself ,sir 7then ,dr7 ,j4 ,henry ,gilbert4 ,they have thus been in progress for a period of fifty years--a fact which was celebrated a few months ago by the presentation of numerous congratulatory addresses from various learned and agricultural societies to the distinguished investigators1 and the erection of a memorial granite slab at ,rothamsted4 ,what increases the feeling of gratitude due to ,sir ,john ,lawes by the agricultural community1 is the fact that the entire expense of conducting these experiments has been borne by himself1 and he has further most generously handed over to the nation a large sum of money and a certain area of land for carrying them on in perpetuity4 ,nature of ,experiments on ,crops and ,manures4 ,the earliest systematic experiments were on turnips1 and since then almost every common crop has been experimented on4 ,table ,i4 7p4 #efb7 is a list of the different experiments1 with their duration1 area1 and number of plots4 ,soil of ,rothamsted4 ,before describing the more striking results of these experiments1 it may be advisable to say that the elevation of the land at ,rothamsted is about #djj feet above sea-level2 that the average rainfall is about #bh inches per annum2 and that the surface-soil is a heavy loam1 and the subsoil a stiff clay1 resting on chalk4 ,,table ,i4--,,list ,,of ,,rothamsted ,,field ,,experiments4 ---------------------------------------- ---------------------------- ,crops4 ,duration4 ,area4 ,plots4 ---------------------------------------- ---------------------------- ,years4 ,acres4 ,wheat 7various manures7 #ej #aa #cd 7or #cg7 ,wheat alternated with fallow #db #a #b ,wheat 7varieties7 #ae #d-h about #bj ,barley 7various manures7 #db #d-a_/d #bi ,oats 7various manures7 #aja #j-c_/d #f ,beans 7various manures7 #cbb #a-a_/d #aj ,beans 7various manures7 #bgc #a #e ,beans1 alternated with wheat #bhd #a #aj ,clover 7various manures7 #bie #c #ah ,various leguminous plants #af #c #ah ,turnips 7various manures7 #bhf #h #dj ,sugar-beet 7various manures7 #e #h #da ,mangel-wurzel 7various manures7 #ah #h #da ------------ ,total root crops #ea ------------ ,potatoes 7various manures7 #ah #b #aj ,rotation 7various manures7 #df #c #ab ,permanent grass 7various manures7 #ch #g #bb ---------------------------------------- ---------------------------- #a4 ,including one year fallow4 #b4 ,including one year wheat and five years fallow4 #c4 ,including four years fallow4 #d4 ,including two years fallow4 #e4 ,clover1 twelve times sown 7first in #ahdh71 eight yielding crops1 but four of these very small1 one year wheat1 five years barley1 twelve years fallow4 #f4 ,including barley without manure three years 7eleventh1 twelfth1 and thirteenth seasons74 ,,wheat ,,experiments4 ,the first experiments we shall refer to are those on wheat1 since they are among the oldest1 and their results the most striking of any4 ,unmanured ,plots4 ,wheat has been continuously grown year after year on three plots for fifty years1 without the application of any manure whatever4 ,we shall first give the results of the first eight years as illustrating the effect of season1 which accounts for the irregular results obtained4 ,but for the difference in seasons1 we should expect to find a steady decrease in the amount of produce2 and this is shown in taking the average of groups of years1 as we shall do in the next table4 ,,wheat ,,grown ,,continuously ,,on ,,same ,,land 7unmanured74 ,,table ,,ii4--7a47 ,remits of first ,eight ,years 7#ahdd to #ahea74 ,year4 ,bushels4 ,year4 ,bushels4 #ahdd #ae #ahdi4 #ai-a_/d #ahde #bc-a_/d #ahej4 #ae-g_/h #ahdf #ah #ahea4 #ae-g_/h #ahdg #af-g_/h ------ #ahdh #ad-c_/d ,average of #h years #ag-c_/h ------ ,,table ,,iii4--7b47 ,results of subsequent ,forty ,years 7#aheb to #ahia74 ,grain ,weight per ,straw 7bushels74 bushel4 7cwts47 #bj years 7#aheb-ahga7 #ad-a_/b #eg-e_/h #ac #bj 7#ahgb-ahia7 #aa-a_/b #eh-c_/d #h-e_/h #dj 7#aheb-ahia7 #ac #eh-a_/d #aj-e_/h #dith season 7#ahia7 #i-c_/h #ei-a_/b #g-a_/b ,it is interesting to notice the comparatively slight decrease which has taken place in the yield of wheat during these fifty years4 ,with such wide variations1 due to season1 it is extremely difficult1 as ,sir ,j4 ,henry ,gilbert has pointed out1 to estimate rate of decline due to exhaustion4 ,excluding the very bad seasons1 this may be reckoned at from one-fourth to one-third of a bushel per acre per annum4 ,the return of the first year is #ae bushels1 while the yield of the forty-ninth season is #i-c_/h bushels4 ,the average of the returns obtained during these fifty years is really in excess of the average yield of the principal wheat-producing countries in the world4 ,this is truly a most astounding result4 ,the next experiments we shall describe are those on the influence of farmyard manure on the wheat crop when grown continuously4 ,,table ,,iv4--,,wheat ,,grown ,,continuously ,,with ,,farmyard ,,manure 7#ad tons per annum74 ,weight per ,bushels4 bushel ,straw 7lb47 7cwts47 #h years 7#ahdd-aheb7 #bh - - #bj 7#aheb-ahga7 #ce-g_/h #fj #cc-g_/h #bj 7#ahgb-ahia7 #cc-a_/b #fj-c_/h #ca-c_/h #dj 7#aheb-ahia7 #cd-g_/h #fj-a_/d #cb-e_/h ,it will be seen from the above results1 which contain merely a selection from a very much greater number of experiments1 that farmyard manure gives as good an average over the forty years as most of the artificial mixtures do4 ,that this is due to the nitrogen it contains1 is strikingly illustrated by the fact that mixed mineral manures alone give less than half the return1 and also by the fact that ammonia salts alone give a return twice as great as mineral mixtures2 while1 lastly1 the mixture of mineral manures and ammonia salts gives but a slight increase over that obtained with ammonia salts alone4 ,the remaining results1 selected from a much larger number1 need no comment1 and we shall give them in tabular form4 ,table ,v4--,,wheat ,,grown ,,continuously ,,with ,,artificial ,,manures1 ,,farmyard ,,manure1 ,,and ,,unmanured4 ,average of ,forty ,years 7#aheb-ia74 ---------------------------------------- ----------------------------------- ,,produce ,,per ,,acre--,,average ,,per ,,annum4 -------------------------------------- ,dressed grain4 ,,manures ,,per ,,acre ,,per ,,annum4 -------------------------------------- ,quantity4 ------------------------------------ #bj years1 #bj years1 #dj years1 #aheb-ga4 #ahgb-ia4 #aheb-ia4 ---------------------------------------- --------------------------------- bush4 bush4 bush4 ,farmyard manure1 #ad tons per annum since #ahdc #ce-g_/h #cc-a_/b #cd-g_/h ,unmanured continuously #ad-a_/b #aa-a_/b #ac ,mixed mineral manures#a and #c-a_/b cwt4 superphosphate #ag #ab-g_/h #ae ,mixed mineral manures1 #c-a_/b cwt4 superphosphate1 #bjj lb4 ammonium salts #bf-a_/b #ba-c_/d #bd-a_/h ,mixed mineral manures and #c-a_/b cwt4 superphosphate1 #fjj lb4 ammonium salts #ch-a_/d #cd-c_/d #cf-a_/b ,mixed mineral manures1 #c-a_/b cwt4 superphosphate1 #bge lb4 nitrate of soda #cf-g_/h #cd #ce-c_/h #bge lb4 nitrate of soda #bf #ai-c_/h #bb-c_/d #djj lb4 ammonium salts every year since #ahde #bb-a_/b #ai #bb-a_/b #djj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate #bh #bb-a_/d #be-a_/h ,mineral manure1 #c-a_/b cwt4 superphosphate1 #djj lb4 ammonium salts in autumn #ca-e_/h #bi-a_/b #cj-a_/b ---------------------------------------- --------------------------------- ---------------------------------------- ------------------------------------ ,,produce ,,per ,,acre--,,average ,,per ,,annum4 -------------------------------------- ,dressed grain4 ,,manures ,,per ,,acre ,,per ,,annum4 -------------------------------------- ,quantity4 ------------------------------------ #bj years1 #bj years1 #dj years #aheb-ga4 #ahgb-ia4 #aheb-ia4 ---------------------------------------- --------------------------------- lb4 lb4 lb4 ,farmyard manure1 #ad tons per annum since #ahdc #fj #fj-c_/h #fj-a_/d ,unmanured continuously #eg-e_/h #eh-c_/d #eh-a_/d ,mixed mineral manures and #c-a_/b cwt4 superphosphate #eh-g_/h #ei #eh-g_/h ,mixed mineral manures1 #c-a_/b cwt4 superphosphate1 #bjj lb4 ammonium salts #ei-c_/h #fj #ei-e_/h ,mixed mineral manures and #c-a_/b cwt4 superphosphate1 #fjj lb4 ammonium salts #ei #fj #ei-a_/b ,mixed mineral manures1 #c-a_/b cwt4 superphosphate1 #bge lb4 nitrate of soda #eh-c_/h #ei-e_/h #ei #bge lb4 nitrate of soda #ef-e_/h #ef-e_/h #ef-e_/h #djj lb4 ammonium salts every year since #ahde #eh #eg-c_/h #eg-e_/h #djj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate #eg-c_/h #eh #eg-e_/h ,mineral manure1 #c-a_/b cwt4 superphosphate1 #djj lb4 ammonium salts in autumn #ei-a_/b #fj #ei-c_/d ---------------------------------------- --------------------------------- ---------------------------------------- ----------------------------------- ,,produce ,,per ,,acre--,,average ,,per ,,annum4 -------------------------------------- ,,manures ,,per ,,acre ,,per ,,annum4 ,total straw4 -------------------------------------- #bj years1 #bj years1 #dj years #aheb-ga4 #ahgb-ia4 #aheb-ia4 ---------------------------------------- --------------------------------- cwt4 cwt4 cwt4 ,farmyard manure1 #ad tons per annum since #ahdc #cc-g_/h #ca-c_/h #cb-e_/h ,unmanured continuously #ac #h-e_/h #aj-e_/h ,mixed mineral manures and #c-a_/b cwt4 superphosphate #ae #i-c_/d #ab-c_/h ,mixed mineral manures1 #c-a_/b cwt4 superphosphate1 #bjj lb4 ammonium salts #bd-a_/b #ai-a_/h #ba-g_/h ,mixed mineral manures and #c-a_/b cwt4 superphosphate1 #fjj lb4 ammonium salts #da-c_/h #ci-e_/h #dj-a_/b ,mixed mineral manures1 #c-a_/b cwt4 superphosphate1 #bge lb4 nitrate of soda #da-a_/b #cg-c_/d #ci-e_/h #bge lb4 nitrate of soda #bh-a_/d #ah-a_/b #bc-c_/h #djj lb4 ammonium salts every year since #ahde #bd-c_/d #af-a_/d #bj-a_/b #djj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate #bf-c_/h #ba #bc-c_/d ,mineral manure1 #c-a_/b cwt4 superphosphate1 #djj lb4 ammonium salts in autumn #ca-a_/d #bh-c_/h #bi-c_/d ---------------------------------------- --------------------------------- #a4 ,by the term mixed mineral manures is meant a mixture of mineral fertilisers1 not including phosphates4 ,table ,,vi4--,,experiments ,,on ,,the ,,growth ,,of ,,barley ,,for ,,forty ,,years1 #aheb-ia4 ---------------------------------------- ----------------------------------- ,,produce ,,per ,,acre--,,average ,,per ,,annum4 -------------------------------------- ,dressed grain4 ,,manures ,,per ,,acre ,,per ,,annum4 -------------------------------------- ,quantity4 ------------------------------------ #bj years1 #bj years1 #dj years1 #aheb-ga4 #ahgb-ia4 #aheb-ia4 ---------------------------------------- --------------------------------- bush4 bush4 bush4 ,unmanured continuously #bj #ac-a_/d #af-a_/b #c-a_/b cwt4 superphosphate of lime #be-a_/b #ag-c_/d #ba-c_/d ,mixed mineral manures #bb-a_/b #ac-a_/b #ah ,mixed mineral manures1 #c-a_/b cwt4 superphosphate #bg-a_/b #ag-a_/d #bb-c_/h #bjj lb4 ammonium salts #cb-a_/b #be-e_/h #bi #bjj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate #dg #ch-a_/b #db-c_/d #bjj lb4 ammonium salts1 mixed mineral manures #ce #bg-c_/d #ca-c_/h ,manures1 #c-a_/b cwt4 superphosphate of lime #df-a_/d #dj-c_/d #dc-a_/b #bge lb4 nitrate of soda #cg #bh-c_/h #cb-c_/d #bge lb4 nitrate of soda1 #c-a_/b cwt4 superphosphate #di-a_/d #db-a_/d #de-c_/d #bge lb4 nitrate of soda1 mixed mineral manures4 #cg-c_/h #bi-a_/b #cc-a_/b #bge lb4 nitrate of soda1 mixed mineral manures1 #c-a_/b cwt4 superphosphate #di-c_/d #da-a_/d #de-a_/b #ajjj lb4 rape-cake #de-a_/d #cg-a_/h #da-a_/d #ajjj lb4 rape-cake1 #c-a_/b cwt4 superphosphate #df-c_/d #dj #dc-c_/h #ajjj lb4 rape-cake1 mixed mineral manures #dc-e_/h #ce-e_/h #ci-a_/b #ajjj lb4 rape-cake1 mixed mineral manures1 and #c-a_/b cwt4 superphosphate #dg-c_/h #ci #dc-a_/d ,farmyard manure1 #ad tons every year #dh-a_/d #di #dh-e_/h ---------------------------------------- --------------------------------- ---------------------------------------- ------------------------------------ ,,produce ,,per ,,acre--,,average ,,per ,,annum4 -------------------------------------- ,dressed grain4 ,,manures ,,per ,,acre ,,per ,,annum4 -------------------------------------- ,quantity4 ------------------------------------ #bj years1 #bj years1 #dj years #aheb-ga4 #ahgb-ia4 #aheb-ia4 ---------------------------------------- --------------------------------- lb4 lb4 lb4 ,unmanured continuously #eb-c_/h #ea-c_/d #eb #c-a_/b cwt4 superphosphate of lime #ec-a_/d #ec #ec-a_/h ,mixed mineral manures #ec #ea-g_/h #eb-a_/b ,mixed mineral manures1 #c-a_/b cwt4 superphosphate #ec-c_/h #eb-c_/h #ec #bjj lb4 ammonium salts #eb-a_/h #eb #eb #bjj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate #ec-c_/h #eb-a_/d #eb-g_/h #bjj lb4 ammonium salts1 mixed mineral manures #eb-c_/d #eb-a_/b #eb-e_/h ,manures1 #c-a_/b cwt4 superphosphate of lime #ed #ed-a_/h #ed #bge lb4 nitrate of soda #eb #eb-a_/h #eb #bge lb4 nitrate of soda1 #c-a_/b cwt4 superphosphate #ec-c_/h #ec-a_/d #ec-a_/d #bge lb4 nitrate of soda1 mixed mineral manures4 #eb-a_/d #eb-c_/d #eb-a_/b #bge lb4 nitrate of soda1 mixed mineral manures1 #c-a_/b cwt4 superphosphate #ec-c_/h #ed #ec-e_/h #ajjj lb4 rape-cake #ec-c_/d #ec-g_/h #ec-g_/h #ajjj lb4 rape-cake1 #c-a_/b cwt4 superphosphate #ec-g_/h #ed-c_/h #ed-a_/h #ajjj lb4 rape-cake1 mixed mineral manures #ec-c_/d #ed-a_/h #ed #ajjj lb4 rape-cake1 mixed mineral manures1 and #c-a_/b cwt4 superphosphate #ec-e_/h #ed-a_/d #ec-g_/h ,farmyard manure1 #ad tons every year #ed-c_/h #ed-a_/d #ed-a_/d ---------------------------------------- --------------------------------- ---------------------------------------- ----------------------------------- ,,produce ,,per ,,acre--,,average ,,per ,,annum4 -------------------------------------- ,,manures ,,per ,,acre ,,per ,,annum4 ,total straw4 -------------------------------------- #bj years1 #bj years1 #dj years #aheb-ga4 #ahgb-ia4 #aheb-ia4 ---------------------------------------- --------------------------------- cwt4 cwt4 cwt4 ,unmanured continuously #aa-c_/d #f-g_/h #i-c_/h #c-a_/b cwt4 superphosphate of lime #ac-c_/h #h-a_/d #aj-c_/d ,mixed mineral manures #ab-a_/d #g #i-e_/h ,mixed mineral manures1 #c-a_/b cwt4 superphosphate #ad-c_/h #h-c_/h #aa-c_/h #bjj lb4 ammonium salts #ah-a_/b #ac-a_/b #af #bjj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate #bg-e_/h #bj-a_/h #bc-g_/h #bjj lb4 ammonium salts1 mixed mineral manures #bj-a_/d #ae-a_/h #ah ,manures1 #c-a_/b cwt4 superphosphate of lime #bh-a_/b #bc-c_/h #be-g_/h #bge lb4 nitrate of soda #bb-a_/h #ae-g_/h #ai #bge lb4 nitrate of soda1 #c-a_/b cwt4 superphosphate #cj-a_/b #bc-c_/h #bg #bge lb4 nitrate of soda1 mixed mineral manures4 #bc-g_/h #ag-a_/b #bj-c_/d #bge lb4 nitrate of soda1 mixed mineral manures1 #c-a_/b cwt4 superphosphate #cb-c_/h #bd-a_/b #bh-a_/b #ajjj lb4 rape-cake #bf-g_/h #bj #bc-c_/h #ajjj lb4 rape-cake1 #c-a_/b cwt4 superphosphate #bh-c_/h #ba-a_/b #bd-g_/h #ajjj lb4 rape-cake1 mixed mineral manures #bg-a_/h #ai-g_/h #bc-a_/b #ajjj lb4 rape-cake1 mixed mineral manures1 and #c-a_/b cwt4 superphosphate #bi-c_/d #ba-g_/h #be-e_/h ,farmyard manure1 #ad tons every year #bh-a_/d #bi-c_/d #bi ---------------------------------------- --------------------------------- ,,table ,,vii4 ,,experiments ,,on ,,the ,,growth ,,of ,,oats1 #ahfi-gh4 ---------------------------------------- ------------------------------- ,,average ,,per ,,annum4 #e ,,years1 #ahfi-gc4 ---------------------------- ,,manures ,,per ,,acre ,,per ,,annum4 ,dressed grain4 ------------------ ,total ,quantity4 ,weight straw4 per bushel4 ---------------------------------------- ----------------------------- ,bushels4 lb4 cwt4 ,unmanured #ai-g_/h #cc-c_/d #aj-c_/h #bjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia1 and #c-a_/b cwt4 superphosphate of lime #bd-a_/b #ce #ac-c_/h #djj lb4 ammonium salts #dg #ce-g_/h #bh-a_/b #djj lb4 ammonium salts1 #bjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia1 and #c-a_/b cwt4 superphosphate #ei #cg #da-a_/h #eej lb4 nitrate of soda #dg-a_/h #ce-a_/b #bg-a_/b #eej lb4 nitrate of soda1 #bjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia1 and #c-a_/b cwt4 superphosphate #eg-a_/b #ce-c_/d #ce ---------------------------------------- ----------------------------- ,,average ,,per ,,annum4 #d ,,years1 #ahgd-gh4 ---------------------------------------- ------------------------------- ,bushels4 lb4 cwt4 ,unmanured #ac-c_/d #ca-a_/d #f #bjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia1 and #c-a_/b cwt4 superphosphate of lime #ac-a_/h #ca-e_/h #f-a_/h #bjj lb4 ammonium salts4 #bh-g_/h #cc-a_/d #ad-a_/h #bjj lb4 ammonium salts1 #bjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia1 and #c-a_/b cwt4 superphosphate #ch #ce-a_/b #bj #bge lb4 nitrate of soda #bf-c_/h #ca-e_/h #aa-a_/h #bge lb4 nitrate of soda1 #bjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia1 and #c-a_/b cwt4 superphosphate #bh-a_/b #cd-a_/h #ad ---------------------------------------- ----------------------------- ,,table ,,viii4--,,experiments ,,on ,,root ,,crops3 ,,swedish ,,turnips4 ,fifteen ,seasons1 #ahef-gj4a ,roots and ,leaves carted off the ,land4 ---------------------------------------- ------------------------------ ,,series #a4 ,standard manures only4 ,,plot4 ,,standard ,,manures4 ---------------------------------------- ------------------------------ ,roots4 ,leaves4 -------------------- ,tons4 cwt4,tons4 cwt4 #a ,farmyard manure1 #ad tons #f #d #j #ag #b ,farmyard manure1 #ad tons1 and superphosphate #f #g #j #af #c ,without manure1 #ahdf1 and since #j #aa #j #c #d ,superphosphate1 each year2 sulphate potash1 soda1 and magnesia1 #ahef-fj #b #af #j #h #e ,superphosphate1 each year #b #ab #j #i #f ,superphosphate1 each year2 sulphate potash1 #ahef-fj #b #g #j #g #g ,superphosphate1 each year2 sulphate1 potash1 and #cf-a_/b lb4 ammonium salts1 #ahef-fj #b #ab #j #g #h ,unmanured #ahec1 and since2 previously part unmanured2 part superphosphate #a #c #j #d ---------------------------------------- ----------------------------- ,note4--,sulphate of ammonia is estimated to contain #bc per cent ammonia1 and muriate of ammonia #bg per cent4 ,ammonium salts1 in each case1 equal parts sulphate and muriate of ammonia of commerce2 and the mixture is estimated to contain #be per cent ammonia4 ,the #cbh lb4 nitric acid 7sp4 gr4 #a4ce7 mixed with sawdust1 and used as a cross-dressing on the plots of ,series #b from #ahef-fj1 were estimated to contain nitrogen #ej lb4 ammonia4 #a4 ,the crops of #ahei and #ahfj failed1 and were ploughed in2 but as the manures were applied1 and there would be accumulation with the soil for the succeeding crops1 the average produce is calculated as for fifteen years--that is1 the produce of the thirteen years is1 in each case1 divided by #ae4 ---------------------------------------- ----------- ,,series #b4 ,,series #c4 ,standard manures1 ,standard manures1 and cross-dressed and cross-dressed with-- with-- #e years1 #ahef-fj1 #e years1 #ahef-fj1 #cjjj lb4 sawdust1 and #bjj lb4 ammonium #cbh lb4 nitric acid4 salts #aj years1 #ahfa-gj1 #aj years1 #ahfa-gj1 #eej lb4 nitrate soda4 #djj lb4 ammonium salts4 ,,plot4 ---------------------------------------- --------- ,roots4 ,leaves4 ,roots4 ,leaves4 ---------------------------------------- ---- ,tons4 cwt4,tons4 cwt4,tons4 cwt4,tons4 cwt4 #a #g #i #a #b #h #h #a #d #b #g #ac #a #c #h #e #a #e #c #j #ai #j #d #j #ac #j #c #d #e #b #j #af #d #ab #j #ad #e #d #ac #j #ah #c #af #j #ae #f #d #aa #j #ad #d #e #j #ac #g #d #ac #j #ad #d #ab #j #ad #h #a #ac #j #e #a #b #j #e ---------------------------------------- --------- ---------------------------------------- ----------- ,,series #d4 ,,series #e4 ,standard manures1 ,standard manures1 and cross-dressed and cross-dressed with-- with-- #e years1 #ahef-fj1 #e years1 #ahef-fj1 #bjj lb4 ammonium salts1#cjjj lb4 sawdust4 and #cjjj lb4 sawdust4 #aj years1 #ahfa-gj1 #aj years1 #ahfa-gj1 #bjjj lb4 rape-cake4 #djj lb4 ammonium salts1 ,,plot4and #bjjj lb4 rape-cake4 ---------------------------------------- --------- ,roots4 ,leaves4 ,roots4 ,leaves4 ---------------------------------------- ---- ,tons4 cwt4,tons4 cwt4,tons4 cwt4,tons4 cwt4 #a #h #af #a #i #h #j #a #d #b #h #ad #a #i #g #af #a #b #c #c #f #j #ad #c #h #j #ac #d #f #ab #a #e #e #h #j #ag #e #e #af #a #g #e #j #j #ai #f #f #f #a #b #e #c #j #af #g #f #ae #a #d #e #i #j #ag #h #c #ai #j #ah #c #ad #j #ai ---------------------------------------- --------- ,,table ,,ix4--,,experiments ,,on ,,mangel-,,wurzel4 ,average of ,sixteen ,seasons1 #ahgf-ib4 ,manures per ,acre per ,annum4 ---------------------------------------- ------------------------------ ,,series #a4 ,standard manures only4 ,,plot4 ,,standard ,,manures4 ---------------------------------------- ----------------------------- ,roots4 ,leaves4 -------------------- ,tons4 cwt4,tons4 cwt4 #a ,farmyard manure1 #ad tons #af #f #b #ag #b ,farmyard manure1 #ad tons1 and #c-a_/b cwt4 superphosphate #af #ab #b #ah #c ,without manure1 #ahdf1 and since #d #i #a #h #d #c-a_/b cwt4 superphosphate1 #ejj lb4 sulphate of potash and #djj lb4 mixed mineral manure #e #h #a #a #e #c-a_/b cwt4 superphosphate #e #j #a #a #f #c-a_/b cwt4 superphosphate1 and #ejj lb4 sulphate of potash #d #i #j #ah #g #c-a_/b cwt4 superphosphate1 #ejj lb4 sulphate of potash1 and #cf-a_/b lb4 ammonium salts #e #ag #a #h ---------------------------------------- ----------------------------- ---------------------------------------- ----------- ,,series #b4 ,,series #c4 ,standard manures1 ,standard manures1 and cross-dressed and cross-dressed with #eej lb4 with #djj lb4 nitrate of soda4 ammonium salts4 ,,plot4 ---------------------------------------- --------- ,roots4 ,leaves4 ,roots4 ,leaves4 ---------------------------------------- ---- ,tons4 cwt4,tons4 cwt4,tons4 cwt4,tons4 cwt4 #a #bb #aa #d #b #bb #c #e #g #b #bc #ab #d #ad #ba #h #e #f #c #ac #g #c #d #f #ad #b #ah #d #ab #ag #c #ae #af #b #c #j #e #ae #ac #c #e #h #aj #c #a #f #ae #ae #b #ah #ad #f #b #af #g #af #j #c #a #af #c #c #j ---------------------------------------- --------- ---------------------------------------- ----------- ,,series #d4 ,,series #e4 ,standard manures1 ,standard manures1 and cross-dressed and cross-dressed with with #bjjj lb4 rape #bjjj lb4 rape-cake4 cake1 and #djj lb4 ,,plot4ammonium salts4 ---------------------------------------- --------- ,roots4 ,leaves4 ,roots4 ,leaves4 ---------------------------------------- ---- ,tons4 cwt4,tons4 cwt4,tons4 cwt4,tons4 cwt4 #a #bd #aa #f #a #bc #g #d #f #b #bc #ab #f #a #bc #a #d #f #c #aj #aa #c #ag #aa #b #c #j #d #bd #ah #e #g #bj #d #c #i #e #aa #g #d #b #ab #c #c #b #f #ba #f #e #g #af #ad #b #ae #g #ba #f #e #i #ag #aj #c #c ---------------------------------------- --------- ,,table ,x4--,experiments with different ,manures on ,permanent ,meadow-land4 ,thirty-six ,years1 #ahef-ia4 ---------------------------------------- ------------------------------------- ,produce per ,acre1 weighed as ,hay4 ---------------------------------------- ------ ,average per ,annum1 ,average per annum1 #bj years1 #ahef-ge #af years1 #ahgf-ia 7#ast crops only74 7#ast and #b;d crops74 ,manures per ,acre per ,annum4 ---------------------------------------- -- #aj years#aj years#bj years #ast #b;d #ahef-fe4ahff-ge4ahef-ge4;crops4crops4,t otal4 ---------------------------------------- --------------------------------- cwt4 cwt4 cwt4 cwt4 cwt4 cwt4 ,unmanured continuously #bb-a_/b #bj #ba-a_/d #ah #h-a_/bbf-a_/b #c-a_/b cwt4 superphosphate of lime #bc-a_/d #ba-a_/d #bb-a_/d #ah #i #bg-a_/b #c-a_/b cwt4 superphosphate of lime1 and #djj lb4 ammonium salts #cc-g_/h #cj-a_/b #cb-a_/d #cj-c_/daj-a_/bda-a_/d #djj lb4 ammonium salts #cj-a_/b #bb #bf-a_/d #ah-a_/daj-a_/hbg-c_/h #bge lb4 nitrate of soda1 #c-a_/b cwt4 superphosphate1 and mixed mineral manure #de-a_/d #dg-e_/h #df-a_/b #da-a_/hab-a_/hec-a_/d #bge lb4 nitrate of soda #cd-a_/d #cc-a_/b #cc-g_/h #cj-a_/haj #dj-a_/h ---------------------------------------- --------------------------------- ,,table ,,xi4--,,experiments ,,on ,,the ,,growth ,,of ,,potatoes4 ,average of ,five ,seasons1 #ahgf-hj4a ---------------------------------------- -------------------------------------- ,,produce ,,per ,,acre--,,tubers4 ,plot ,,manure ,,per ,,acre ,,per ,,annum4 ---------------------------------------- ,good4 ,small4 ,diseased4 ,total4 ---------------------------------------- ----------------------------------- ,plot ,tons cwt4 ,tons cwt4 ,tons cwt4 ,tons cwt4 #a ,unmanured #a #ah #j #f-a_/d #j #b-a_/d #b #f-a_/b #b ,farmyard manure 7#ad tons7 #c #ai-c_/h #j #g-e_/h #j #f-e_/h #d #ac-e_/h #c ,farmyard manure 7#ad tons71 and #c-a_/b cwt4 superphosphate #d #i-a_/b #j #h #j #h-c_/d #e #f-a_/d #d ,farmyard manure 7#ad tons71 #c-a_/b cwt4 superphosphate1 and #eej lb4 nitrate of soda #e #h #j #g #j #ai-a_/b #f #ad-a_/b #e #djj lb4 ammonium salts #a #ai-a_/b #j #g-a_/h #j #c-a_/b #b #aj-a_/h #f #eej lb4 nitrate of soda #b #aa-g_/h #j #f-g_/h #j #e-a_/d #c #d #g #djj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate1 #cjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia #e #ad-a_/d #j #h-a_/d #j #ad-c_/d #f #ag-a_/d #h #eej lb4 nitrate of soda1 #c-a_/b cwt4 superphosphate1 #cjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 #ajj lb4 sulphate magnesia #e #ai-g_/h #j #g-g_/h #j #ai-a_/h #g #f-g_/h #i #c-a_/b cwt4 superphosphate #c #j-c_/d #j #h #j #d-e_/h #c #ac-c_/h #aj #c-a_/b cwt4 superphosphate1 #cjj lb4 sulphate potash1 #ajj lb4 sulphate soda1 and #ajj lb4 sulphate magnesia #c #d-a_/b #j #f-a_/b #j #d-g_/h #c #ae-g_/h ---------------------------------------- ----------------------------------- #a4 ,in each year the tops were spread on the respective plots4 ,,table ,,xii4--,,experiments ,,on ,,the ,,growth ,,of ,,potatoes--,continued4 ,average of ,twelve ,seasons1 #ahha-ib4 ---------------------------------------- ------------------------------------- ,,produce ,,per ,,acre--,,tubers4 ,plot ,,manure ,,per ,,acre ,,per ,,annum4 ---------------------------------------- ,good4 ,small4 ,diseased4 ,total4 ---------------------------------------- ---------------------------------- ,tons cwt4 ,tons cwt4 ,tons cwt4 ,tons cwt4 #a ,unmanured in #ahgf1 and each year since #a #c-c_/d #j #c-c_/d #j #j-a_/d #a #g-c_/d #b ,unmanured in #ahhb1 and since2 previously farmyard manure 7#ad tons7 #b #ad-a_/d #j #d-c_/d #j #b #c #a #c ,farmyard manure 7#ad tons7 alone1 #ahhc1 and since2 previously #c-a_/b cwt4 superphosphate also #d #c-a_/d #j #d-a_/d #j #d-a_/b #d #ab #d ,farmyard manure 7#ad tons7 alone1 #ahhc1 and since4 ,in #ahhb and previously #c-a_/b cwt4 superphosphate1 and in #ahha and previously #eej lb4 nitrate of soda also #d #f-a_/d #j #d-a_/b #j #d-c_/d #d #ae-a_/b #e #djj lb4 ammonium salts #a #b-c_/d #j #d-c_/d #j #j-a_/b #a #h #f #eej lb4 nitrate of soda #a #ag-c_/d #j #c-c_/d #j #j-c_/d #b #b-a_/d #g #djj lb4 ammonium salts1 #c-a_/b cwt4 superphosphate1 #cjj lb4 sulphate of potash1 and #bjj lb4 mixed mineral manure #e #f-c_/d #j #e #j #d-a_/b #e #af-a_/d #h #eej lb4 nitrate of soda1 #c-a_/b cwt4 superphosphate1 #cjj lb4 sulphate of potash1 and #bjj lb4 mixed mineral manure #e #g-a_/b #j #d-a_/d #j #c-c_/d #e #ae-a_/b #i #c-a_/b cwt4 superphosphate #b #ag-c_/d #j #c-a_/d #j #a #c #b #aj #c-a_/b cwt4 superphosphate1 #cjj lb4 sulphate of potash1 and #bjj lb4 mixed mineral manure #c #b-a_/d #j #c-a_/d #j #a-a_/d #c #f-c_/d ---------------------------------------- ---------------------------------- ,,footnotes3 #bef ,see ,sir ,john ,bennet ,lawes1 ,bart41 and the ,rothamsted ,experiments4 ,by ,c4 ,m4 ,aikman4 7',scottish ,farmer' ,office1 ,glasgow47 ,,index4 ,abraum salts1 #dba4 ,absorptive power of soils for water1 #fg1 #ih2 how to increase1 #gd4 ,acidity in soils neutralised by lime1 #deh4 ,acids fixed by soil1 #eh4 ,adametz on organisms in soil1 #ib4 ,adulteration of guano1 #cah-cbj4 ,africa1 guano from1 #bih1 #cbh4 ,agricultural chemistry1 historical introduction to1 #c-fa2 ,liebig's researches on1 #bc-cb2 ,liebig's services to1 #ca4 ,agronomy1 #ef4 ,air1 ammonia in1 #dh1 #aah2 nitrates in1 #aah2 nitrites in1 #aah2 nitrogen in1 #aaf2 organic nitrogen in1 #aah4 ,aitken1 ,dr1 experiments with basic slag1 #dac --with beans1 #ebf1 #ecj2 on germ-life in bones1 #cfh2 on manuring of turnips1 #eae4 ,albert1 ,heinrich1 on solubility of basic slag1 #dji4 ,albite1 composition of1 #ajc4 ,albuminates1 #dfj4 ,albuminoids1 in plants1 #dia2 of milk1 nitrification in1 #ahb2 phosphorus in1 #bje4 ,algerian phosphate1 #cgi4 ,algoa ,bay1 guano deposits at1 #cbh4 ,alkalies1 in cow-dung1 #bbf1 #bbg --cow-urine1 #bcj --horse-dung1 #bbf1 #bbg --horse-urine1 #bcj --pig-dung1 #bbf1 #bbg --pig-urine1 #bcj --sheep-dung1 #bbf1 #bbg --sheep-urine1 #bcj4 ,alkalinity necessary for nitrification1 #agb4 ,alumina1 in ash of plants1 #ee2 compounds1 reversion caused by1 #chh1 #djj2 salts1 in salinas1 #cce4 ,america1 virgin soils of1 #acc4 ,american farming1 #hf4 ,amides1 #eja4 ,ammonia1 absorbed by soil1 #ha2 amount dissolved in rain1 #di2 amount in air1 #dh2 amount in soil1 #abg2 amount supplied to soil by rain1 #aee2 converted into nitrates in soil1 #ej2 converted into nitrous acid1 #afg2 fixed by soil1 #eh2 from decomposition of farmyard manure1 #beh2 from gas-works1 #cec2 lost in mixing manures1 #ecc2 relation of1 to plants1 #dh-ej2 salts1 most easily nitrifiable1 #aia2 salts of1 in farmyard manure1 #beg2 sulphate of1 #ceb-ceh2 value of1 as a manure1 #ceb4 ,ammonium chloride in ,chincha guano1 #cje4 ,ammonium-magnesium phosphate in ,chincha guano1 #cje4 ,ammonium oxalate in concretionary nodules1 #cbh4 ,ammonium phosphate1 in ,chincha guano1 #cje2 in concretionary nodules1 #cbh4 ,ammonium sulphate1 #ceb-ceh2 in ,chincha guano1 #cje2 in concretionary nodules1 #cbh4 ,ammonium sulphocyanate1 #cee4 ,ammonium urate in concretionary nodules1 #cbh4 ,amphibole1 potash in1 #bbj4 ,analysis1 of manures1 #eci-eed2 of soils1 value of1 #ij4 ,anderson1 ,dr1 analyses of minerals by1 #ajc1 #aje-ajg2 on nitrogen in soil1 #aba1 #abd4 ,angamos1 guano from1 #cja1 #cbi4 ,animals1 phosphoric acid in1 #bje2 potash in1 #bje2 solid excreta of1 #bbd2 urine of1 #bbh4 ,apatite1 ,canadian1 #bja1 #cgd2 composition of1 #baj2 most abundant form of phosphoric acid1 #bjj2 varieties of1 #bjj4 ,application of manures1 #dgd-dib4 ,arabian coast1 guano deposits on1 #cbh4 ,arable soil1 absorptive power of1 #ih4 ,arbrohlos ,island guano1 #cji4 ,arendt1 experiments on oats by1 #ejc4 ,aristotelian doctrine of chemical elements1 #d4 ,artificial soil1 #ed4 ,aruba phosphate1 #cjh1 #cbh1 #cgi4 ,ash1 constituents of plants1 #ec-ee2 of rye1 phosphoric acid in1 #bjd2 of wheat1 phosphoric acid in1 #bjd2 of farmyard 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superphosphate1 #chc2 on manurial constituents of foods1 #bhb2 on nitrification in alkaline solutions1 #aig2 on nitrogen in excrements1 #bcc2 on nitrogen in soil1 #abb2 on potash in wool1 #bbg2 researches of1 on nitrification1 #ce1 #eb1 #aff-afh1 #ahj1 #ahf4 ,water1 absorbed by plants1 #gc2 amount of1 transpired by plant-leaves1 #ef2 an adulterant of guano1 #cai2 a carrier of plant-food1 #ee2 in cow-dung1 #bbf --cow-urine1 #bcj2 from decomposition of farmyard manure1 #beg2 in horse-dung1 #bbf --horse-urine1 #bcj2 necessary for plant1 #fg2 in pig-dung1 #bbf --pig-urine1 #bcj --sheep-dung1 #bbf --sheep-urine1 #bcj2 transpired by elm-tree1 #ga --oak-tree1 #ga4 ,water-culture1 #ed4 ,water-logged soils1 #agi4 ,waterloo1 bones from1 #cfj4 ,way1 ,thomas1 on retention of plant-food by soil1 #eg1 #ei2 on sewage1 #dcg4 ,west ,indies1 guano from1 #bih4 ,whales1 guano from1 #cbb4 ,wheat1 fertilising ingredients removed from soil by1 #dhe2 ,flitcham experiments on1 #ejj2 manurial constituents in1 #bhb2 manuring of1 #dii-eja nitrogen removed in crop of1 #ade2 requires nitrogenous manures1 #dii2 ,rothamsted experiments on1 #ejj1 #efb-efe2 a source of nitrogen1 #aec4 ,wheat soils1 nitrates in1 #aeg4 ,wheat-straw1 analysis of stable manure made from1 #bhc2 composition of1 #bch2 manurial constituents in1 #bhb4 ,white clover1 growth of1 promoted by lime1 #dea4 ,wiegmann on ash constituents of plants1 #ec4 ,wilfarth on nitrogen in plants1 #dd4 ,wilting1 #gc4 ,winogradsky1 on nitrification1 #eb1 #afg1 #afi1 #aig2 on organisms in soil1 #id4 ,wolff on1 analysis of manure-heap drainings1 #bij2 composition of fresh and rotten dung1 #bhh2 assimilation of organic nitrogen by plants1 #dg2 relative manurial value of manurial compounds1 #eef2 urine1 #bcb4 ,wood-ashes as potash manure1 #bah1 #dai4 ,woodhouse1 researches of1 on nitrogen in plants1 #da4 ,wool1 capable of nitrification1 #ahb2 potash in1 #bag4 ,wool-waste1 #dbg2 nitrogen in1 #dbg4 ,woolney1 on organisms in soils1 #ic1 #ie2 on water in soils1 #ge4 ,wrightson1 ,professor1 on application of basic slag1 #dad4 ,yeast1 #id4 ,yorkshire1 bones first used in1 #cei4 ,zeolites1 potash in1 #bbj ,,printed ,,by ,,william ,,blackwood ,,and ,,sons4 ---------------------------------------- ----------- ,transcriber's ,note3 ,carats 77 signify superscript figures4 ,underscores 77 followed by a number in curly brackets signify subscript figures4 ,typographical errors corrected in the text3 ,page #eh ,eichorn changed to ,eichhorn ,page #acd diferent changed to different ,page #dfd superposphate changed to superphosphate ,page #eec biophosphate changed to biphosphate ,page #egi ,gallopagos changed to ,galapagos ---------------------------------------- -----------