,atoms in ,agriculture ,the ,understanding the ,atom ,series ,nuclear energy is playing a vital role in the life of every man1 woman1 and child in the ,united ,states today4 ,in the years ahead it will affect increasingly all the peoples of the earth4 ,it is essential that all ,americans gain an understanding of this vital force if they are to discharge thoughtfully their responsibilities as citizens and if they are to realize fully the myriad benefits that nuclear energy offers them4 ,the ,united ,states ,atomic ,energy ,commission provides this booklet to help you achieve such understanding4 ,illustration3 ,edward ,j4 ,brunenkant1 ,director ,division of ,technical ,information ,,united ,,states ,,atomic ,,energy ,,commission ,dr4 ,glenn ,t4 ,seaborg1 ,chairman ,james ,t4 ,ramey ,wilfrid ,e4 ,johnson ,dr4 ,theos ,j4 ,thompson ,dr4 ,clarence ,e4 ,larson ,atoms in ,agriculture by ,thomas ,s4 ,osborne ,,contents ,,research ,,in ,,the ,,united ,,states #a ,,how ,,are ,,radioisotopes ,,used ,,in ,,research8 #b ,they ,may be ,used as 8,tracers0 #b ,how ,effective ,are ,radioactive ,tracers8 #c ,,plant ,,nutrition ,,and ,,metabolism #d ,what ,happens to ,fertilizer in the ,soil8 #d ,do ,plants ,absorb ,through ,roots ,only8 #d ,where ,should ,fertilizer be ,placed8 #e ,do ,fertilizers ,move ,fast in ,plants8 #e ,what ,else ,do ,radioisotopes ,tell ,us8 #e ,,plant ,,diseases ,,and ,,weeds #h ,how ,can ,we ,combat ,plant ,diseases8 #h ,why ,do ,chemicals ,destroy ,some ,plants8 #aj ,,animal ,,nutrition ,,and ,,metabolism #aa ,how ,nutritious ,are ,various ,feedstuffs8 #aa ,can ,lean ,meat be ,estimated 8on the ,hoof08 #ab ,does ,thyroid ,affect ,milk--,egg ,production8 #ac ,more ,tracers in ,animal ,nutrition ,research #ac ,,insects #ae ,where and ,how ,fast ,do ,insects ,travel8 #ae ,how ,far ,do ,insects ,carry ,pollen8 #ae ,are ,predators ,used to ,destroy ,insects8 #af ,can ,tracers ,measure ,spray ,residues8 #ag ,,radioisotopes ,,as ,,radiation ,,sources #ag ,can ,radiation ,produce ,new ,plants8 #ah ,can ,radiation ,destroy ,germs and ,insects8 #ai ,how ,does ,radiation ,affect ,farm ,animals8 #bb ,what ,else ,can ,radiation ,tell ,us8 #bb ,,conclusion #bc ,,suggested ,,references #bd ,united ,states ,atomic ,energy ,commission ,division of ,technical ,information ,library of ,congress ,catalog ,card ,number3 #fd-fjbgd #aifb2 #aifc7,rev47 ,,about ,,the ,,author ,thomas ,s4 ,osborne is in charge of plant-breeding research being conducted by the ,university of ,tennessee's ,agricultural ,research ,laboratory for the ,atomic ,energy ,commission4 ,he has been in this work since #aiec4 ,but ,dr4 ,osborne is a teacher at heart4 ,hence when students wrote inquiring about the effects of radiation on seeds1 he took great interest in replying4 ,from these replies grew mimeographed literature suggesting experiments for students2 then this and other booklets4 ,dr4 ,osborne received his undergraduate degree from ,oklahoma ,state ,university and his doctorate from ,washington ,state ,university4 ,atoms in ,agriculture by ,thomas ,s4 ,osborne1 ,associate ,professor of ,agronomy1 ,university of ,tennessee4 ,to know what questions to put to ,nature--that is #ie per cent of scientific research4 --,whitehead ,if man's existence on the earth is compared to a calendar year1 then he began farming in the very early morning of ,december #cj and began applying systematic knowledge to agriculture at #aj3ae p4m4 on ,december #ca4 ,the first traces of man on the earth are dated at about one and three-quarter million years ago4 ,plant life then was very much like plant life today1 but the animal population was quite different4 ,man became a producer of plants and animals instead of merely a gatherer and hunter about #hjjj years ago4 ,he has applied systematic study to cultivated plants and animals for only #cjj years4 ,research in the ,united ,states ,estimates of crop losses in the ,united ,states each year are approximately #e billion to weeds1 #d billion to insects1 and #c billion to diseases4 ,this total loss of #ab billion a year is about #bb1ejj a minute4 ,in an effort to reduce these losses and to raise the standard of living1 agricultural research has become more specialized and more complex4 ,over the years it has gradually changed from trial-and-error attempts to increase production to the actual study of basic questions4 ,to study such intricate systems as the leaf of a plant or the liver of an animal1 agricultural science has had to draw from every other science4 ,the use of radioactive tracers and radiations in research looks especially promising to agriculture4 ,in fact1 agriculture has already begun to benefit from the applications of such research4 ,radioactive techniques have been used to study soils1 plants1 microbes1 insects1 farm animals1 and new ways to use and preserve foodstuffs4 ,radioactive atoms are not used directly by farmers but are used in research directed by the ,u4 ,s4 ,department of ,agriculture and ,atomic ,energy ,commission1 by the agricultural experiment stations of the various states1 and by numerous public and private research institutions4 ,from such research come improved materials and methods which are used on the farm4 ,in more highly developed countries agricultural research has brought a shift of emphasis from production to utilization4 ,in the ,united ,states today1 each farmer produces enough food for himself and #be other people4 ,moreover1 for every person who works on a farm1 there are two or three other people who sell him goods and services or process and distribute the things he produces4 ,in agriculture1 as in all areas of research1 the number of questions to be asked of ,nature seems infinite4 ,future generations seeking to answer these questions will probably rely more on techniques using radioactive isotopes than on any other methods known today4 ,how ,are ,radioisotopes ,used in ,research8 ,they ,may ,be ,used as 8,tracers0 ,man's attempts to describe the universe consist of finding answers to the questions he puts to ,nature3 ,how deep is a well8 ,toss in a rock4 ,where is the cat8 ,hang a bell on him4 ,how far does a wild duck fly8 ,put a marker on his leg4 ,where are the fireflies8 ,just watch at dusk4 ,is our satellite still up8 ,listen for the radio signal4 ,other questions arise in agricultural research3 ,how fast do roots grow8 ,how deep8 ,how soon does water get to them after a rain8 ,when does a mouthful of hay reach a cow's stomach8 ,how long until nutrients get into her blood8 ,her milk8 ,how far will pine pollen travel on the wind8 ,how deep does an earthworm burrow8 ,to answer these questions1 scientists need some kind of miniature genie1 one who will shout at the proper moment1 8,i'm here60 ,when the root has reached the fertilizer or the water has reached the root2 when the hay becomes transmuted to milk1 or the earthworm arrives at a particular spot--then this invisible little servant who has made the trip could announce1 8,i'm here60 ,such a helpful genie exists as the radioactive atom3 he is invisibly small1 obedient1 transportable1 digestible1 immune to fire1 flood1 or famine1 able to travel under his invisible cloak to the secret hiding places of ,nature's creatures and announce to waiting ,geiger tubes1 8,i'm here60 ,the physically unstable radioactive atom behaves chemically exactly like its stable counterpart until the instant it emits its radiation and becomes stable4 ,for example1 radioactive phosphorus behaves1 biologically and chemically1 like stable phosphorus until it emits a beta particle and becomes stable sulfur4 ,if the beta particle enters a gas-filled ,geiger tube1 it produces a tiny burst of electrical energy which is registered by the counter4 ,like fireflies which reveal themselves at dusk by flashes of light1 radioisotopes announce their numbers and locations to sensitive ,geiger tubes by flashes of invisible 8light40 ,how ,effective ,are ,radioactive ,tracers8 ,one way to see how valuable radioactive tracers are is to compare them to standard chemical techniques4 ,a sensitive chemical test can perceive molecules as dilute as #aj2 that is1 it can detect a molecule surrounded by #aj million molecules of another kind4 ,a good radioactive tracer technique1 by comparison1 can distinguish concentrations of #aj2 that is1 it can trace one in #ajj billion4 ,in other words by the chemical test you could find a person in metropolitan ,new ,york with a secret tattoo on the roof of his mouth4 ,by the tracer method you could find this same person anywhere in the world1 even if the world population were multiplied fiftyfold4 ,in the chemical test you could distinguish the equivalent of one kernel of corn in one-tenth of a boxcar load2 in the tracer1 one kernel in #hej boxcars4 ,plant ,nutrition and ,metabolism ,most studies of plant nutrition and metabolism pertain to the following questions4 ,what do plants need for their best growth8 ,how do they take in the materials they need8 ,what things are absorbed by roots and what things by foliage8 ,how does the plant turn water and other simple compounds into carbohydrates and proteins8 ,specific problems that atomic energy has helped to solve are listed4 ,what ,happens to ,fertilizer in the ,soil8 ,early research indicated that only #aj to #ab per cent of phosphorus fertilizers was taken up by plants in the first year2 the rest was 8locked into0 the soil or washed away4 ,with radioactive phosphorus-#cb scientists found that as much as #ej to #gj per cent of the phosphorus in a plant came from the fertilizer during the first two or three weeks of growth4 ,do ,plants ,absorb ,through ,roots ,only8 ,fertilizer applied to soil is largely wasted because it is either bound by soil particles or is washed out of the root zone4 ,if chemical elements could go directly into leaves and bypass the wastefulness of soils1 a tremendous saving would result4 ,botanists have learned in recent years that the foliage of plants can take in some nutrients much as roots can4 ,with tracers they discovered that many nutrients are readily taken up by foliage1 including bark of dormant trees1 even at temperatures below freezing4 ,as shown by isotopic tracers1 elements such as phosphorus1 nitrogen1 and potassium move both up and down from the point of application at rates similar to those following root absorption4 ,urea 7a nitrogen compound7 is now used as a nutrient foliar spray for many fruit and vegetable crops in this country4 ,where ,should ,fertilizer ,be ,placed8 ,even before the use of tracers1 agronomists realized the inefficiency of spreading fertilizer uniformly over a seed-bed4 ,they know the fertilizer should be placed somewhere near the seed1 but where8 ,above8 ,below8 ,beside8 ,below and beside8 ,how far away8 ,they had conducted some research1 but the methods were slow and tedious4 ,using tracers1 the researchers confirmed earlier findings that roots within two or three days reached fertilizer placed less than two inches directly below seeds1 but the roots tended to congregate there4 ,when the fertilizer was two inches below and two inches to the side1 roots reached it within a week and a better root system developed4 ,with three inches between seeds and fertilizer1 the desired seedling 8boost0 was delayed three or four weeks4 7,see ,fig4 #a47 ,do ,fertilizers ,move ,fast in ,plants8 ,the movement of radioactive phosphorus from root to leaf was found to be remarkably fast1 sometimes requiring less than twenty minutes4 7,see ,fig4 #b47 ,what ,else ,do ,radioisotopes ,tell ,us8 ,some plants take in chemicals that the plant probably cannot use3 for example1 the so-called locoweeds accumulate enormous amounts of selenium4 ,with tracer techniques1 we can see that the root uptake process has poor powers of discrimination4 ,fig4 #a--,soil tests tell how much of each fertilizer element is needed but not where to put it to give seedlings the much-needed 8push40 ,with tracers it is found that3 ,illustration3 7,a7 ,fertilizer mixed throughout the soil gives the least benefit to seedlings4 ,illustration3 7,b7 ,if placed in a band below and beside the seeds1 the fertilizer gives high uptake and good root distribution4 ,illustration3 7,c7 ,if the fertilizer is placed directly beneath the seeds1 highest uptake occurs but roots tend to 8bunch0--a handicap to later growth4 ,fig4 #b--,radioactive plant nutrients injected in soil roots ,illustration3 have not reached above ground parts in #e minutes ,illustration3 but have1 as indicated by ,geiger counter1 reached these parts in #bj minutes4 ,illustration3 ,tracer experiments reveal that roots cannot distinguish potassium 7needed in large amounts7 from other elements which are chemically similar but quite different in size4 ,once inside the plant1 only potassium can be metabolized and similar but heavier elements 7rubidium1 cesium7 are useless4 ,this is like an absentminded builder who buys brick1 boulders1 and gravel indiscriminately for his wall and then finds he can use only part of his materials4 ,the process called photosynthesis whereby green plants use energy from the sun to convert simple compounds from air and soil into complex1 energy-rich substances has been termed the most important chemical reaction in the world4 ,it is the basis for man's entire food supply and1 except for nuclear energy1 all significant fuel as well4 ,tracer techniques have multiplied the research efforts on photosynthesis tremendously4 ,when only chemical tests were available1 food manufacturing in green leaves had to progress for hours before scientists could measure the products4 ,but with tracers and other new techniques they have narrowed the experimental time to minutes and finally to seconds4 ,today they know that a green leaf has formed sugars more complex than fructose1 8fruit sugar10 after exposure to light for only one second6 ,when the incredible complexities of photosynthesis are finally unraveled1 radioactive tracers1 especially radioactive carbon-#ad1 will have provided the significant clues4 ,plant ,diseases and ,weeds ,how ,can ,we ,combat ,plant ,diseases8 ,at one time to stop epidemic spread of plant diseases was virtually impossible2 farmers had to abandon fields and crops4 ,such catastrophes caused by microbes have changed the course of history4 ,for example1 the ,irish famines of the #ahdj's resulted from the potato blight and caused mass emigrations from ,ireland4 ,in this country today plant diseases result in losses estimated at #c billion a year4 ,so far1 the most economical means of reducing the ravages of plant diseases has been to breed resistant plant varieties4 ,although such a variety may cost #ajj1jjj to develop1 its cost is usually repaid within a year or two4 ,but the victory is only temporary4 ,although plants are bred to resist the pathogen 7fungus7 of the moment1 ,nature is constantly changing the microbial population by mutation and hybridization4 ,within a few years virulent strains of fungi which can attack the 8resistant0 variety increase to such an extent that the new variety must be replaced4 ,for crops that provide high per-acre income such as some vegetables and vine and tree fruits1 chemical control of fungous diseases is economically possible2 in fact1 it is a real necessity4 ,but such treatment is too costly for most field crops1 unless some cheap seed treatment or fertilizer additive can be found4 ,a general breakthrough in control of plant diseases is yet to come4 ,because of thousands of pathogenic species1 with hundreds of strains1 it does not seem possible that the following questions could be answered about each one4 ,what is the life cycle of the microbe8 ,what conditions of temperature and humidity encourage it to spread8 ,what plant species does it attack8 ,how does it enter8 ,what chemical changes within the cells of the plant determine whether they resist or succumb to the invader8 ,how long can germs remain potent8 ,how far can they travel by wind or water8 ,what combination of resistant varieties1 cultural methods1 and chemical treatment will control the disease8 ,with tracers it is possible for the first time to measure chemical uptake in single spores and to follow chemicals through the plant4 ,perhaps the most enlightening information from such studies is that some fungicides are #aj1jjj times less effective per unit of 8body weight0 than are other chemicals used to destroy weeds and insects4 ,obviously the breakthrough in chemical control of plant diseases is yet to come4 ,why ,do ,chemicals ,destroy ,some ,plants8 ,weeds cost this country an estimated #e billion annually1 which is more than the loss to either plant diseases or insects4 ,selective chemical weed killers such as 8#b1 #d-;,d0 have become so widely used that more than #ace million worth was sold in the ,united ,states in #aiei4 ,in proper concentration these compounds will destroy many unwanted plants without harming lawn grasses or crop plants4 ,illustration3 ,fig4 #c--,tagged weed-killing chemicals 7,a7 are taken in and transported alike in grassy 7,b7 and broad-leaved 7,c7 plants1 but only in the latter are killed4 ,as in many other instances1 beneficial use of the chemicals has far outreached an understanding of how they work4 ,the still scanty knowledge of the process has come almost entirely from tracer studies4 ,all plants readily absorb selective weed killers 78herbicides071 which are not destroyed within the plants4 ,resistant plants show no effect of the chemicals1 but sensitive plants suffer damage in actively growing roots and shoots4 ,sugar formation during photosynthesis is disrupted in these plants1 and phosphorus movement is retarded4 ,in order to predict what new classes of chemicals might be of value as herbicides1 we must await the results of research using radioactive tracers4 ,animal ,nutrition and ,metabolism ,how ,nutritious ,are ,various ,feedstuffs8 ,an endless phase of animal nutrition research deals with efficiency of rations1 that is1 the pounds gained by the animal per pound of feed consumed4 ,the standard form of such research is to feed groups of animals on different rations for several weeks or months and determine average change in weight per pound of feed used4 ,in recent years scientists have used chemical tests to compare the amount of calcium in the diet against the amount excreted4 ,the apparent digestibility of such minerals has thus been computed for different rations4 ,yet one important source of error in these chemical tests plagued researchers4 ,there is a 8turnover0 in nutrients fed to animals2 elements in feed are absorbed into the animal's body1 retained for a time1 and later excreted4 ,for example1 a cow actually loses more calcium 7through milk and excreta7 during the first six months of milk production than her normal ration contains4 ,as long as the amount of recycling was unknown1 scientists could not tell1 for instance1 how much calcium in alfalfa hay could be digested by simply measuring incoming and outgoing calcium4 ,formerly scientists could study the problem only by withholding all calcium from the diet4 ,under this unnatural condition all outgoing calcium came from the animal's body4 ,with radioactive calcium in a steer's diet 7or injected into the blood71 scientists can quickly tell how much of the excreted calcium comes from the animal's blood and organs under normal conditions4 ,in a typical instance a ration thought to have #bd per cent digestible calcium1 chemically determined1 was found to have #ch per cent by the tracer technique4 ,the tracer method shows that milk contains phosphorus1 only #bj per cent of which may come from the feed and #hj per cent from the cow's bones4 ,with eggs1 about #fe per cent of the phosphorus is provided by feed and #ce per cent by the hen4 ,radioactive tracers permit measurement of such 8biological pathways10 as the biochemist calls them4 ,can ,lean ,meat be ,estimated 8on the ,hoof08 ,the proof of the ration1 one might say1 is in the cutting4 ,that is1 the worth of a particular feed was formerly unknown until the carcass had been cut and priced4 ,because of the time and expense1 researchers in the past have merely tested groups of animals on a ration for a few weeks and then estimated the total gain by weighing and measuring4 ,the main drawback to such a method is that it measures total growth only4 ,in meat animals1 knowing total growth is less important than knowing how much gain is in the more valuable lean meat1 how much is in fat1 and how much merely water4 ,techniques based on atomic energy have provided a new approach without adding radioactive contamination to the animal4 ,of the 8background radiation0 that has existed since the earth was formed1 part comes from cosmic rays 7from outer space7 and part from radioactive materials in the earth itself4 ,one of these naturally radioactive isotopes is radioactive potassium1 which is present to a small but significant extent in food1 in human bodies1 and in construction materials4 ,while some chemicals such as carbon1 hydrogen1 and oxygen go into almost every kind of substance in living things1 potassium plays a special role in animals3 it lodges almost exclusively1 not in bone or fat or water1 but in lean meat4 ,biological and medical researchers are now cooperating to build 8whole-body0 radiation counters4 ,a human being or an animal is actually enclosed by these huge devices1 some of which are so sensitive they measure nearly every ray that emerges from the body4 ,these counters will help answer many questions1 but here only their use to measure radiopotassium in meat animals is explained4 ,the animal is fed a test ration containing no added radioactivity4 ,at intervals of a week or more1 the animal is weighed and is also tested for natural radioactivity4 ,weighing tells total gain1 while radiopotassium counting shows how much gain is in the desired lean meat4 ,this method is remarkably simple1 and since no radioactivity is added to its diet1 the animal can still be marketed4 ,does ,thyroid ,affect ,milk--,egg ,production8 ,recognition of the significance of the thyroid gland in animals1 the association of iodine with the thyroid1 and the availability of an excellent radioisotope of iodine have resulted in increased study of this important gland4 ,chemical tests had hinted at a link between the thyroid gland and the production of milk and eggs4 ,using radioactive iodine1 scientists learned that thyroid activity increases with the onset of milk and egg formation4 ,in hot weather1 when yield of milk and eggs decreases1 activity of the thyroid gland diminishes4 ,it may be that a dairy breeder can soon select calves for potential milk production because of thyroid activity as measured by radioactive iodine4 ,at present he must let the animals grow and produce milk for several years before he chooses those to use in herd improvement4 7,see ,fig4 #d47 ,more ,tracers in ,animal ,nutrition ,research ,female hormones in microgram amounts#a accelerate fattening of cattle and sheep4 ,before this method can be used on animals for human consumption1 however1 it must be determined that no possible human injury can result from any residue4 ,with chemical tests the measurement of such tiny amounts was impossible4 ,even with radioactive carbon-#ad1 doses of hormone #ajjj times normal dosage were required before the hormones in the flesh were measurable4 ,fig4 #d--;,future high-producing milk cows may be selected as calves1 because of the measured activity of their thyroid glands4 ,a minute amount of iodine-#aca is fed and within minutes has concentrated in the thyroid4 ,high concentration means high thyroid activity1 which in older animals means high milk production4 ,illustration3 ,iodine-#aca fed 444 concentrates in thyroid4 ,recently an isotope of hydrogen 7tritium or ,h7 was linked to hormones1 and these were fed in normal amounts to cattle4 ,tests #ij days afterward showed less than one part per billion in the meat1 a big step toward cheaper fattening of meat animals with hormones4 ,the use of tranquilizers has been proposed for reducing the customary loss of weight in cattle being shipped to market4 ,these chemicals1 also1 are used in such minute quantities that residues could not be detected except with radioactive tracers4 ,tritium can now be used by health officials to study the effects of tranquilizers4 ,insects ,where and ,how ,fast ,do ,insects ,travel8 ,radioactive isotopes have been used to study insects1 their life cycles1 dispersion1 mating and feeding habits1 parasites1 and predators4 ,several hundred such studies have been made on dozens of insect species4 ,with radioactive tracers even the smallest insect becomes more easily followed4 ,as one example1 nearly half a million mosquito larvae were tagged with radioactive phosphorus in ,canada4 ,some of the adults from these larvae were later found as far as seven miles away1 but most were recovered within one-eighth mile4 ,in a companion study grasshoppers were labeled with the same isotope4 ,their average rate of movement was only twenty-one feet per hour1 and after seven days their position was based entirely on random motions plus prevailing winds4 ,it seems that grasshoppers have no ability to move toward food4 ,how ,far ,do ,insects ,carry ,pollen8 ,this question is of practical importance in knowing how far to separate seed-fields to maintain pure varieties of plants4 ,in the past it was studied by the laborious method of growing a plant having a dominant 8marker0 gene for some visible trait surrounded by plants without the marker4 ,seeds from plants at various distances from the marked plant were grown the following year to see how far the genetically marked pollen had been carried4 ,since such plants are normally cross pollinated1 it was difficult to obtain strains genetically pure for presence or absence of the marker gene4 ,also1 considerable testing and bookkeeping were involved4 ,with tracers the answer may be found in a few days4 ,a plant is injected with radioactive phosphorus2 after a few days its pollen is highly radioactive4 ,flowers at various distances from the tagged plant may be checked daily for radioactivity4 ,in one study with alfalfa1 radioactive pollen was carried as far as thirty feet by bees1 but more than one-third was deposited on plants adjacent to the labeled one4 ,are ,predators ,used to ,destroy ,insects8 ,with insect pests1 as with plant diseases1 biological control is more economical than artificial control4 ,the use of insecticides too often results in destruction of helpful insects along with pests4 ,limited success has been achieved in breeding certain plants for resistance to insects4 ,two important uses of biological control in agriculture have been made in recent years3 importing an insect from ,australia to eradicate a weed in ,california and disseminating ladybird beetles to control certain scale insects4 ,fig4 #e--;,identifying predators that destroy unwanted insects4 ,illustration3 ,aphids are made radioactive4 ,illustration3 ,larger insects found nearby are checked for radioactivity4 ,bumblebee has not eaten radioactive aphids1 but mantis has4 ,helpful parasites and predators must first be identified before they can be used4 ,in the case of small or nocturnal insects1 this can be exceedingly troublesome4 ,tagging the pests with radioisotopes in order to identify the predators which consume them is much simpler because the most efficient predators contain the most activity4 ,with such techniques entomologists have studied insects and animals which prey on unwanted aphids1 mosquitoes1 blackflies1 and roaches4 ,such experiments may lead to a deliberate increase of certain predators to control injurious insects4 ,radioactive labeling is also valuable in studying helpful insects4 ,in one case the indolence of drone bees was indicated by finding that even with adequate syrup in their cage they still received identical syrup from worker bees in an adjoining cage6 ,can ,tracers ,measure ,spray ,residues8 ,any material used on plants or animals to kill insects or disease organisms must pass rigid inspection to be sure it does not accumulate in foodstuffs4 ,this is particularly true of the 8systemic0 poisons1 those which are fed to plants via leaves or roots and are carried internally to all parts of the plant4 ,such chemicals can be used widely with nonfood plants such as cotton to kill insects feeding on them4 ,combining radioactive labeling with other techniques has permitted the researchers to show that some compounds are soon broken down into harmless chemicals--a big step toward acceptance for their use on food plants4 ,radioisotopes as ,radiation ,sources ,earlier in this booklet radioisotopes were compared to fireflies because they emit flashes of 8light40 ,isotopes serve research in another important way1 other than as tracers4 ,suppose you collected all the fireflies within a #ajj-mile radius and put them into a glass jar4 ,instead of an occasional twinkle1 you would now have a steady glow of light4 ,similarly immense numbers of radioactive atoms can be compressed into a small volume to produce steady1 intense sources of radiation4 ,agricultural research has answered many questions with the use of such radiation sources4 ,can ,radiation ,produce ,new ,plants8 ,perhaps no biological aspect of atomic energy has so caught the fancy of the public as the prospect of creating new plant varieties4 ,there is something mysterious about pouring invisible energy into seeds or buds and watching for changes in the emerging leaves and flowers4 ,there is also the challenge of the lottery in being unable to predict where1 when1 or in what form the alterations will appear4 ,although the claims of over-enthusiastic gardeners and seed dealers about astonishing new plants 8created0 by atomic radiation are doubted1 clear proof exists even in the restrained scientific journals of hereditary changes caused by radiation4 ,from more than #cj years of scientific study1 certain conclusions have emerged4 ,high-energy radiations can cause sudden hereditary changes 7mutations7 in any living thing3 man1 animal1 microbe1 or plant4 ,any feature of a plant subject to hereditary control--root1 shoot1 leaf1 flower1 or fruit--can be altered by radiation4 ,most of these changes are undesirable2 they interfere with the normal state of biological affairs4 ,a very small percentage of mutated organisms is improved in some way4 ,so far changes cannot be controlled or predicted4 ,to date fourteen new strains of crop plants improved by radiation have been put into production in various parts of the world4 ,these varieties with their places and dates of release follow3 #a4 8,primex0 white mustard1 ,sweden1 #aiej #b4 8,chlorina ,mutant0 tobacco1 ,indonesia1 about #aiej #c4 8,shafer's ,universal0 bean1 ,germany1 about #aiej #d4 8,regina ,,ii0 summer oil rape1 ,sweden1 #aiec #e4 8,weibull ,stralart0 fodder pea1 ,sweden1 #aieg #f4 8,sanilac0 navy bean1 ,michigan1 #aieg #g4 8,pallas0 barley1 ,sweden1 #aieh #h4 8,n4 ,c4 #d,x0 peanut1 ,north ,carolina1 #aiei #i4 8,florad0 oats1 ,florida1 #aifj #aj4 8,seaway0 bean1 ,michigan1 #aifj #aa4 8,alamo-,x0 oats1 ,texas1 #aifa #ab4 8,gratiot0 bean1 ,michigan1 #aifc #ac4 8,pennrad0 barley1 ,pennsylvania1 #aifc #ad4 8,yukon-#a0 carnation1 ,connecticut1 #aifc ,in these instances no desirable changes appeared in the plant grown directly from treated seeds1 but they appeared several generations later4 ,in most cases hundreds of thousands of plants were examined before the desirable ones were found4 ,the desired changes were almost always accompanied by undesirable ones1 and years of cross-breeding and 8purifying0 were necessary to obtain usable varieties4 ,the technique of radiation breeding can be used on any form of life where large numbers can be grown and discarded at little cost4 ,the output of penicillin has been increased a thousandfold by repeated mutations caused in the microorganism producing this antibiotic4 ,several studies on radiation breeding of poultry have been started4 ,an ingenious reverse twist of induced mutation is being applied in the field of plant diseases4 ,while some scientists are irradiating seeds and plants in an effort to obtain disease-resistant mutations1 others are irradiating the fungi which cause the diseases4 ,they hope in this way to foresee the new strains of pathogenic microbes that will occur naturally in order to breed resistant plants before the new diseases appear4 ,some claims have been made that radiation can stimulate plant growth1 germination1 earlier maturity1 and so on4 ,similar benefits are sometimes claimed for human health4 ,these allegations are almost never proved in reputable laboratories4 ,it seems likely that radiation is stimulating1 in the words of one authority1 8only in the sense that a pruning knife is stimulating40 ,can ,radiation ,destroy ,germs and ,insects8 ,food technologists have studied ways of preserving food with radiation for more than ten years4 ,their findings indicate that complete sterilization of food with radiation requires doses so high 7#b to #f million roentgens#b7 that cost is prohibitive at present1 and the food often becomes distasteful4 ,these amounts of energy completely destroy the microbes and enzymes which normally cause food to putrefy4 ,if radiation is to be used in preserving food1 it will probably be as a supplement to conventional methods of heating and freezing4 8,pasteurizing0 with radiation to destroy most 7but not all7 of the microbes in meat or fruit or vegetables is accomplished with less than five per cent of the dosage required for sterilizing4 ,such treatment does not alter flavor or texture appreciably and could be used to prolong the refrigerated 8life0 of many fresh foods4 ,it is the responsibility of the ,federal ,food and ,drug ,administration to determine that no threat to human welfare could possibly result before approving the use of high-energy radiation to preserve foods4 ,with agricultural products stored dry1 such as grain1 tobacco1 and wool1 the chief agents of damage are not microbes1 but insects4 ,the loss of stored field crops caused by insects is estimated at #bjj million annually in the ,united ,states4 ,deinfesting such goods with radiation doses in the 8pasteurizing0 range promises to be practical and causes no apparent change in the product4 ,like many other foodstuffs1 potatoes are often stored for months between harvest and use4 ,precaution must be taken to prevent their deterioration during storage not only from decay but also from sprouting4 ,cold storage inhibits sprouting but is costly and has another serious drawback4 ,in the making of potato chips1 tubers held at low temperature contain excess sugar and result in darkened chips4 ,storage at higher temperatures prevents conversion of starch to sugar but encourages sprouting4 ,atomic energy promises to resolve this dilemma4 ,given low doses of gamma rays 7#ejjj to #aj1jjj roentgens71 potatoes may be kept at room temperature for a year or more without sprouting4 ,similar doses inhibit sprouting of onions4 ,the estimated cost of irradiating tubers and bulbs at such doses is as low as #ad cents per ton4 ,no chemical changes have yet been found in irradiated potatoes that would make them unsafe for eating4 ,in fact1 health officials in ,canada have recently approved the use of gamma rays on potato tubers that will be stored and later used for human food4 ,our own ,food and ,drug ,administration has given similar approval for applying gamma rays to bacon and fast electrons to wheat 7for killing insects74 ,an ingenious application of atomic energy to agriculture concerns the screwworm fly1 which inhabits large areas of southern ,united ,states1 ,mexico1 and the ,caribbean4 ,the fly lays eggs in open wounds of livestock1 including navels of newly born1 and the burrowing maggots inevitably kill the animal4 ,in the southeastern ,united ,states1 damage from this insect amounted to #ae to #be million annually4 ,in the years #aieh and #aiei more than two billion screwworm flies were deliberately released from airplanes over the entire state of ,florida and parts of ,georgia and ,alabama4 ,this astonishing act was a major step in successful eradication of the pest from southeastern ,united ,states4 ,the entomologists who conceived this remarkable scheme had the following information from basic studies3 the insect produces a generation about every three weeks4 ,in the pupal stage males can be sterilized by #bejj roentgens of ,x or gamma rays1 females by #ejjj roentgens4 ,the insect can be reared in large numbers4 ,sterile males are fully competitive with normal males for mates4 ,and1 of course1 sterile eggs do not hatch4 7,it was helpful1 though incidental1 that females mate only once47 ,after initial tests on an island in the ,caribbean1 a large fly-producing plant was set up4 ,flies were grown to the pupal stage1 irradiated with #hjjj roentgens of gamma rays1 permitted to mature1 and released from airplanes4 ,with #ej million flies being released weekly over ,florida1 ,georgia1 and ,alabama1 the area was smothered with sterile flies1 and the number of eggs that hatched 7from the normal native flies7 rapidly diminished to zero4 ,the program was continued for #ah months1 and in this time the insect was completely eliminated4 ,certain other insects are being considered for the sterility-eradication technique4 ,among them are the boll weevil1 ,european corn borer1 mosquito1 and tsetse fly4 ,oriental scientists are using gamma rays instead of the conventional heating to kill silkworms inside cocoons4 ,how ,does ,radiation ,affect ,farm ,animals8 ,at a few colleges of agriculture in this country1 radiation effects on farm animals are being studied4 ,although it may not be flattering to be likened to a pig or a donkey1 the fact remains that human beings are physiologically very similar to swine and burros4 ,these animals are mammals with simple stomachs and have the same general size1 shape1 and placement of organs as do humans4 ,radiation studies with swine and burros1 although slow and expensive1 should give information more applicable to humans than the more rapid and inexpensive studies with small laboratory animals4 ,what ,else ,can ,radiation ,tell ,us8 ,two characteristics of soils besides fertility are vitally important and difficult to measure4 ,these characteristics are moisture and density4 ,moisture must be determined frequently for efficient irrigation4 ,density controls the pore space available for water and oxygen2 the possible damage to the soil from tillage and harvesting machines is revealed by before-and-after tests of density4 ,both soil moisture and density were formerly determined by laboratory methods1 which had two drawbacks3 the methods were laborious1 and they tested soil in an unnatural state4 ,today a sort of double-barreled radiation method can be used to measure these two soil characteristics4 ,neutrons are readily scattered by water but not by soil2 gamma rays are absorbed by both soil and water4 ,in practice the experimenter drills two holes in the soil a few feet apart4 ,into one he puts a gamma-ray source2 into the other1 a radiation detector4 ,the reading on his detector dial tells him the amount of gamma rays absorbed by both soil and water4 ,replacing the gamma-ray source with a neutron source1 he obtains a reading on absorption by water only4 ,the difference between the two readings is ascribed to the density1 or degree of compaction1 of that soil in its native state4 ,conclusion ,radioactive tracers and radiation sources have become indispensable to all phases of agricultural research4 ,they have helped answer questions that seemed unanswerable4 ,but there will always be more questions to put to ,nature4 ,the physicists-philosophers of #ahij were confident that they had obtained all significant knowledge of the physical universe4 ,discoveries of the next twenty years revealed the immaturity of that conviction4 ,the modern poet ,archibald ,mac,leish has dramatized the meagerness of knowledge3#c ,i will tell you all we have learned 444 the lights in the sky are stars ,we think they do not see we think also ,the trees do not know nor the leaves of the grasses hear us4444 ,perhaps the most characteristic realization of the scientist today is that the universe is too complex to be fully described1 that concepts must change repeatedly to absorb new findings1 and that the recurring miracle of life is more majestic than any formula1 any computer1 or any rocket that man's brain can devise4 ,suggested ,references ,applications of ,radioisotopes and ,radiation in the ,life ,sciences4 ,hearings before the ,subcommittee on ,research1 ,development and ,radiation of the ,joint ,committee on ,atomic ,energy1 ,congress of the ,united ,states1 ,march #bg-cj1 #aifa4 ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office1 ,washington #be1 ,d4 ,c4 #aifa1 #eac pages1 #a4ej4 ,experiments with ,radiation on ,seeds4 ,thomas ,s4 ,osborne4 ,u4 ,s4 ,atomic ,energy ,commission1 ,division of ,technical ,information ,extension1 ,oak ,ridge1 ,tenn4 ,no4 #a1 #aa pages2 ,no4 #b1 #cj pages1 free4 ,oklahoma ,conference--,radioisotopes in ,agriculture4 7,proceedings of a conference held at ,oklahoma ,state ,university1 ,april #b and #c1 #aiei47 ,,tid-#gegh4 ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office1 ,washington #be1 ,d4 ,c4 #aiei1 #bhg pages1 #b4jj4 ,radioactive ,isotopes in ,agriculture4 7,proceedings of a conference held at ,michigan ,state ,university1 ,january #ab-ad1 #aief47 ,,tid-#geab4 ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office1 ,washington #be1 ,d4 ,c4 #aief1 #daf pages1 #c4jj4 ,radioisotopes in ,science and ,industry4 ,u4 ,s4 ,atomic ,energy ,commission4 ,superintendent of ,documents1 ,u4 ,s4 ,government ,printing ,office1 ,washington #be1 ,d4 ,c4 #aifj1 #agf pages1 #a4be4 ,what ,can ,you ,expect from ,atomic-,irradiated ,seeds8 ,james ,l4 ,brewbaker4 ,u4 ,s4 ,atomic ,energy ,commission1 ,division of ,technical ,information ,extension1 ,oak ,ridge1 ,tenn4 ,not dated1 #h pages1 free4 ,motion ,picture 7,available for loan without charge from the ,division of ,public ,information1 ,u4 ,s4 ,atomic ,energy ,commission1 ,washington #be1 ,d4 ,c47 ,harvest of an ,atomic ,age1 #bj minutes1 #afmm1 color and sound1 #aifc4 ,footnotes #a;,a microgram bears the same relationship to a #ajjj-pound steer as a penny does to #d billion4 #b,the roentgen is a measure of ionizing radiation1 as the foot-candle is a measure of light4 ,in simple terms the roentgen is that amount of ,x or gamma radiation which produces one electrostatic unit 7esu7 of electricity in one cubic centimeter 7cc7 of dry air at standard conditions of temperature and pressure4 ,this may sound like a trivial amount of energy1 but it amounts to more than two billion ionizations in each cubic centimeter4 #c;,from 8,epistle ,to ,be ,left in the ,earth40 ,transcriber's ,notes --,retained publication information from the printed edition3 this e,book is public-domain in the country of publication4 --,where possible1 ,,utf superscript and subscript numbers are used2 some e-reader fonts may not support these characters4 --,in the text version only1 underlined or italicized text is delimited by underscores4 --,in the text version only1 superscript text is preceded by caret and delimited by brackets4 --,in the text version only1 subscripted text is preceded by underscore and delimited by brackets4 --,in the text version only1 added a brief label to each illustration2 and for graphs1 provided tabular summaries of the data where possible4