FRIENDLY WORKERS of the SOIL Ten Lessons A study of soil-bacteria, in relation to practical farming Published 1921 j= 0 M SCOTT & SONS " Marys-ville> Ohio C O N T E N TS LESSON I— An Invisible World LESSON II— Fighting the Destroyers LESSON I l l- Bacterial Armor LESSON IV— Friendly Helpers on the Farm LESSON V— The Food of Plants LESSON VI— Conditions of Bacterial Life LESSON VII— The Soil Factory LESSON VIII— The Waste of Nitrogen Page 3 4 6 7 9 10 13 16 LESSON IX— Putting Plant Food Into the Soil . .. 18 LESSON X— The Indispensable Condition 21 Copyright, 1921, O. M. Scott & Sons Co. The purpose of this booklet is to tell in a clear and concise manner the story of the bacterial life of the soil, par- ticularly in its relation to practical farming. LESSON I AN INVISIBLE WORLD Bacteria are minute living organ- isms, visible only under the eye of a powerful microscope, and so Defined3 s i mPle of structure that their classification as plants rather than animals long remained uncertain. A particle of matter may contain many thousands of bacteria. Water, earth and air are teeming with this unseen life in its infinite variety. Some bac- teria are harmful to higher forms of life; they are the disease producers. Others are the busy workmen of na- ture's bounty, enriching the earth and making possible life for plants and ani- mals. Many of the results of bacterial ac- tivity, such as putrefaction and fer- mentation, h a ve been Existence Of Bac- fa mi i iar to man since ,, tena First Discov- t he beginning of time, ered in 1675 b ut t he existence o f bacteria themselves became known only near the end of the seventeenth cen- • u * tury. Their discovery was made possi- ble by the perfecting of the compound microscope which made visible to man a new world of plant and animal life. Since then the petrified cells of bac- teria have been discovered in the rocks, making clear that they existed before the age of man, and in forms not very dissimilar from those of today. They were first definitely recognized in 1675 by a Dutch scientist, Leeuwenhoek, who called them "animalcules." The different forms of bacterial life are recognized not only by their ap- pearance under the mi- nizfng Bacteria^" ™ O p e, but also by the various chemical changes they produce in the matter in which they live. They are both de- stroyers and builders, transforming plant and animal matter into new sub- stances. LESSON II FIGHTING THE DESTROYERS is of absorbing The study of disease-producing bac- interest and teria has largely made pos- present-day Medical Science g i b le ofXCcttiay y achievements in medi- cal science. Antiseptic surgery by which amazing operations are performed was the result of this study. Today no surgeon would think of touching the human body with a o ur knife without first sterilizing it, that is, destroying such bacterial life as might carry infection to the wound. Our effective control of contagious dis- eases was made possible by the same study. Vaccination for smallpox and inoculation for typhoid, for example, have incalculably diminished the rav- ages of these diseases. It will be of interest to note the ap- pearance of bacteria as seen under the microscope. There are three Of Baecter?aS Pr i n c iPal types which have been described as reminding one of billiard balls, lead pencils and corkscrews. The first type is seen as chains or clusters of balls, the sec- ond as elongated cells often joined to each other at the ends, and the third frequently as twisted threads. The spherical bacteria average about one twenty-five thousandth of an inch in diameter, while the others may be as much as one thousandth of an inch in length. Some bacteria move about in a liquid medium; while others appear to be motionless. Bacteria propagate themselves by splitting into halves, thus forming two ™ u ^ r distinct organisms w h i ch a2a in h a ve Growth vide. As this process may be completed in as short a time as half an hour, it will be seen that bacterial life, t he P °w er t0 di- under favorable circumstances, may in- crease with amazing rapidity. The limitations of increase are pro- vided by two factors. First, the ex- f o od MeTroduNcSa r y?«PPl^ and second, the accumulation m the medium surrounding the bacteria of injurious substances, as, for exam- ple, the excretions of the bacteria them- selves. haustion of LESSON III BACTERIAL ARMOR As a means of preserving life under adverse conditions, many bacteria have the power of producing Spores and Their Relation spores. The spores have To Bacteria been c a l l ed "bacterial eggs," but the use of the phrase must not lead to a misunderstanding. The spore is a bacterial body changed into a more resistant form by being sur- rounded by a tough cell wall. The spore may retain life amid unconge- nial surroundings for a long period, even years. When brought into favor- able conditions it bursts open, produc- ing a new bacterial cell which multi- plies in the usual manner. In pasteurizing liquids, as milk, suffi- cient heat is used to destroy bacterial cells but not the spores. Sterilization j. •> implies the destruction of cells and spores alike. A condition which affects, favorably or unfavorably, the life and growth of bacteria i s temperature. Aids to Bac- Active life, in some spe- terial Growth . • cies, may be found withm the range of only a few degrees, the bacteria protecting themselves against unfavorable heat or cold by spore for- mation. Some spores resist extreme heat, while others may be frozen in ice and resume activity when the ice is melted. An amount of water also is neces- sary. In the case of bacteria living in humus in the soil, activity practically ceases when there is only two or three per cent of moisture, and is most no- ticeable with twenty-five or thirty per cent. In vegetable or animal substances more water is necessary. Some bacteria require oxygen taken from the air, while for others the pres- ence of air is death. Sunlight, on the whole, is destructive to the bacterial world. Sunlight is na- ture's germicide. LESSON IV FRIENDLY HELPERS ON THE FARM The practical farmer who reads this booklet may naturally question what l i fe g r e a t ly g a i n i ng the subject of bacte- ri0lOgy h as to do w i t h%is a Why a Knowledge of Bacteriology? living from the soil. It has much to do with it. The study of bacteriology gives us a new insight into the reasons for soil fertility and aids in a very practical way in increasing the produc- ing power of our fields. The soil of the field is the medium in which lives a countless variety of bac- terial life, and upon Relation of Bacteria t h ig d e p e n ds To Soil Fertility t he ^a n s f o r_ mation of the soil into food for our growing crops. Our understanding of the bacteria aids us in maintaining and building up the soil capital of the farm. In a number of industries, such as treating milk and milk products, can- fish, tanning of ning, pickling of leather and curing of tobacco, the sci- ence of bacteriology has been found of inestimable v a l u e. Agriculture can profit by it no less. The bacteria of the soil are nature's scavengers, extracting from the humus, that is, the decaying Renovating Power of b o d i es of pla n ts and Bacteria in the Soil e l e_ ments as carbon, hydrogen, nitrogen and sulphur, and setting them free as food elements for another generation of plant and animal life. Without their a n i m a l s> g u ch activity, dead matter would accumu- late and life would fail for want of food. The number of these friendly work- ers in the soil depends upon several conditions. As a degree of moisture is necessary for their development, they are increase after rain. Warmth, too, is necessary. Spores ly- ing dormant in frozen earth must wait for the sun of springtime to rouse them to activity. In the warm and moist months of early summer they work most rapidly. found to LESSON V THE FOOD OF PLANTS e J e m e nt jg f o od Let us see more clearly how this transformation of dead material into plant food takes place, of Carbon 0 ne neCessary p l a n t- c a r b o n. lo me riant This enters largely into the construc- tion of the tissues. It is said that nearly a ton of carbon each year is re- quired as food by an acre of beech for- est. The fibre of rye straw contains forty per cent of carbon. This food is obtained by the green plant from the air in the form of carbon dioxide gas which it decomposes, building the car- bon in its tissues. It is evident that this gas must be constantly renewed in the in t he air or the plant food will be exhausted and the world of vegetation will starve. There are several ways in which this renewal is accomplished. Carbon is set free in the burning of WWch Carbon W 0°d a nd C O al a nd is Obtained°n breath of animals. More important, however, is the liberation of carbon dioxide gas in the decay of organic matter. In this process of decay, as we have seen, the bacteria have an essential part. The bacteria are the tireless de- stroyers of dead vegetable organisms. Stubble, roots, leaves, twigs and all the discarded material of field and forest are transformed by them, and their food elements set free. LESSON VI CONDITIONS OF BACTERIAL LIFE He fields# l i fe of h is It will now be evident that of most practical interest to the farmer is the maintenance of the bacte- Maintaining r i al in thTsoil will need to understand the conditions upon which de- pend the number and activity of these friendly workers of the soil. First among these conditions, as we have said, is the presence of moisture. Pro- tracted drouth is a hindrance to bac- terial life. Their number and activity naturally increase after rain. Bacteria which require air for their nourishment thrive best in sandy soil which allows air penetration. Those which cannot live in air are naturally found in clay. Crops grown on the soil also affect materially the nature and number of bacteria in it. A p r i m a r y r e a s on for c r 0p rotation is to By Crop ° a l on create favorable conditions for a large variety of bacteria, thus insur- ing the proper transformation of hu- mus into plant food. A factor of great importance in bac- terial development is the application of fertilizers and manures. F^t i l i z e rs Barnyard manure, for ex- and Manures * ample, being rich m bacte- ria, greatly increases their number in the soil. The application of lime also has effects upon bacterial life which are long persistent. Humus, composed of decaying vege- table and animal organisms, is, in gen- eral, the food of the soil By Increasing bacteria. There is, how- Humus ever, one important excep- tion, that of certain nitrogen-fixing bacteria, which are to be spoken of later. The number of bacteria is af- fected not only by the amount of this humus food, but also by its character. The raw humus of swamps and peat lands, acid in character, is a poor food, • , • j.9 i <, • , . i of g a nd or it. Consider in l o am pe r s i s tent appli- It is evident that the nature of the soil will affect greatly the bacterial life t he Relation of Soil To Bacterial Life cation of fertilizers seems to have no lasting effect. The soil remains light and the crops thin. This is due largely to the too rapid transformation of the humus under the attacks of an intense Q bacterial life. Little water aanay Loam jg r e t a i n ed jn its looseness permits a rather free cir- culation of air. Under these conditions certain air-loving bacterial species mul- tiply greatly, and the decay of the hu- mus becomes a sort of slow burning and it is too rapidly exhausted. t h ig s o il a nd , T and for the proper increase of bacterial life such lands must be drained and limed. field g a n dy It is evident that such land, to be cropped profitably, must have large and repeated applications of humus- forming material. Green - manuring also is practicable, as the food elements of decaying vegetation are rapidly lib- erated. Again, here is a field of clay, its soil C1 fine-grained and compact. There ay is little space for the circulation of air. Bacterial life does not thrive under these conditions and the disinte- T gration of humus takes place too slowly. In the ease of water-logged soil and swamp land the presence of excessive . moisture accomplishes the 0 Swamp Land s a me r e s u lt Here organic matter tends to putrefaction rather than decomposition into plant food. But a small portion of the humus be- comes carbon dioxide. Part of it es- capes from the soil as marsh-gas, while some of it remains as humic acids, making the land sour. For the proper development of bacterial life in such land, drainage and liming are neces- sary. LESSON VII THE SOIL FACTORY s e n ü al vital interest to p l a n t_f o od Let us now consider those forms of life of most practical and bacterial t he Bacteria A Nitri- fa r m e r. Among the es- fymg Agent e l e_ ments is nitrogen. This element con- stitutes about f o u r - f i f t hs of the atmosphere surrounding the earth and permeating the soil. Most of the nitro- gen plant-food is derived from the dis- integration of humus, which is broken down by the bacteria of the soil and made available for the plant. This process must be noted with some care. The food of plants, as of , , . J y . animals, is composed of carbohydrates, fats and How Plants , Assimilate Food proteins. Plants do not feed directly upon soil-humus or even upon the elements of which soil-humus is composed. Unlike animals, the plant has power within itself to change ele- ments into food, but the humus must first be broken down and the elements set free. This is the work of one group of friendly bacteria. The breaking down of the humus into the nitrogen food element is a complex matter, con- sisting of three distinct operations, and for these three operations at least three distinct sorts of soil bacteria are neces- sary. No one species is competent to do the entire work. . ~ ®, We may liken the soil to a factory in which humus is manufactured into t he plant - food e 1 e - The Soii-A Plant m e nt n i t r o g e n. In Food Factory ,, . this factory the raw material passes successively through three operations at the hands of three sets of workmen. These workmen are specialists in their own craft and those of one trade cannot do the work of the others. of the raw material The first process is the transforming into ammonia. There are many kinds of bacteria that can do this. Plant Food T h is transformation is a To Ammonia chemical c h a n ge pro- duced in the process of digestion. While bacteria must digest their food, like animals, they do this outside the body cavity. As the digestive organs of the animal produce pepsin, so the bacteria may produce chemical fer- ments called enzymes which pass out through the cell wall, causing a chem- ical change in such protein food sub- stances as may be adjacent. This di- gested food is then assimilated by the organism. In the digestive process am- monia is produced. The second operation in food-element production performed by a different set of workmen, is the trans- Nitrite and forming of ammonia into ni- trite. The difference between a nitrite and a nitrate is that the nitrate contains three parts of oxygen to one of nitrogen, and the nitrite only two. The third operation effected by a third set of workmen is the transfor- mation of nitrite into nitrate. This is an element which the plant can change into its own food. The bacteria necessary to these three operations are called the nitrifying Friendly Workers of the Soil bacteria. We need The Difference Between to carefully d i s- , ¿ ¿v»^™ Nitrogen-freeing and Nitrogen-fixing Bacteria 11 n g U 1 S fl tnem from the nitrogen- ñxing bacteria to be considered later. The nitrifying bacteria are busy work- men in nature's factory, but they use only the material at hand. The nitro- gen-fixers are the wealth accumulators of the soil store-house, importing nitro- gen from the air and enriching the earth with their merchandise. They are thus indispensable, and the study of their habits and the conditions under which they thrive is of great practical use to the farmer. LESSON VIII THE WASTE OF NITROGEN Not all of the nitrogen produced by the bacteria becomes nourishment for the crop growing in the Chief Means is soil. M u ch 0 f it °f Valorization w a s^ed a n (i o ne problem of practical farming is 2! Leaching 10n the prevention of this waste. There are two ways in which waste takes place. One is the setting free of gaseous nitrogen to return to the atmosphere. This happens when, as in sandy soil, the humus transfor- mation takes place too rapidly. The other notable means of waste is the SPf leaching out of nitrates in soluble In this case excessive rainfall form. washes the nitrates into the subsoil where they cannot be reached by the roots of surface-growing plants. Of primary importance is the char- acter of the soil bacteria. It has been S?en t h at C e r t a in Waste Through Unfriendly Bacteria c i es a re necessary to the formation of ni- trates, and upon the number and strength of these species the amount of the available nitrogen food-element largely depends. Other species make use of considerable quantities of the nitrates in the building of their own bodies, thus becoming actual competi- tors of the plants for the nitrogen of the soil. Still other species return nitrogen to the air in a gaseous form, thus working to the detriment of the crop. The importance of the presence in the soil not only of bacteria, but of the right kind of bacteria, is thus evi- dent. LESSON IX PUTTING PLANT FOOD INTO THE SOIL k ti We come now to the consideration of ^ * a^- „ practical methods by ™ Nitrogen to the^Sofl which the farmer can add to the nitrogen food value of the soil. The first is the direct application to the land of nitrogen salts, such as n i t r a te of soda. i t^- , i . 1. Direct Application TT t h is H o w e v e r, method is costly, unnecessary and usu- ally inadvisable, except for very poor land or in intensive gardening. The second method is that of return- ing humus to the soil in the form of barnyard manure. The farmer thus conserves and uses a part of the hu- ~ „ mus-forming mate- 2. Barnyard Manure ^ h i f l* c r o p S- The value and necessity of this sort of fertilization is so well understood as to require no emphasis. However, this is to be said. The farmer cannot possibly hope to return to the land by this method alone as much plant-food mate- rial as has been removed by the grow- ing crop. It is asserted that, on tight floors, 75 per cent of the fertilizing ele- ments contained in feed may be recov- ered in manure. It is evident that 25 per cent must be lost to the soil. Be- , ,, Qf . ^vw sides, there is inevitably some loss by leaching after the manure has been ap- plied to the soil. Every product sold off the farm„ whether in grain or live stock, means the removal of soil value. Manuring must be supplemented by some other means of enriching the land. The third method is one of simple co-operation with nature. It is the * o ^ process of drawing 3- S S S S t t S Sr nitrogen from the air to supply the soil. This is accomplished by the grow- ing of legume crops, a familiar and generally used method. Among the legumes used for this purpose are the clovers, alfalfas, soy beans and cow peas. The peculiar value of clover in enriching the soil was well understood in the eighteenth century, but the reason for this value yj AAA w as a s u b j e ct of How Legumes Add Nitrogen to the Soil speculation. It was a supposition that roots brought food from the subsoil and made it available in surface humus for succeeding crops. The problem began to work toward its right solution in 1886, when it was observed that peas grown in artificial soil, containing no nitrogen compounds, usually died after the nitrogen of the the deeply penetrating ,. popular j . °Ti_ seed itself was exhausted and that those which survived to maturity inva- riably had developed nodules on the roots. Nodules are tubercle-like swell- ings, rather small on clover and larger on other legumes. It had been pre- viously found that the root nodules were formed and occupied by colonies of bacteria. These discoveries led to the conclu- sion that the bacteria of the root nodules have the power of Nodules11 °f acQu*r*n9 ^he free nitrogen of the air contained in the soil and transforming it into food ma- terial for the plant. They penetrate the root hairs from the soil, and, find- ing a favorable place for development, pass from one cell of the plant to an- other, reaching the interior of the root. The root then enlarges and the nodule is formed. The plant supplies the bacteria with sugar and with other needed food-sub- stances and in return the bacteria make the nitrogen of the air available as a food element for the plant. The le- gumes are thus able, with the assist- ance of the bacteria, to derive nitrogen from the air, a peculiarity possessed by no other plant family. This nitrogen is eventually given by the plant to the soil. It is estimated that the quantity of nitrogen thus utilized would be worth from sixteen to thirty dollars per acre if bought in the form of nitro- gen salts. The bacteria which perform this op- eration are nitrogen-fixing bacteria. ^a ve a l r e a dy Function of SymbioticBacteria Pointed out their dis- tinction from nitrify- ing bacteria, which only transform the they have already material which found waiting their labor in the soil factory. The bacteria associated with the legumes, called the symbiotic bac- teria, are not the only bacteria of the soil which have the power of taking nitrogen from the air, but, for the pur- poses of practical farming, they are the ones requiring special consideration. LESSON X THE INDISPENSABLE CONDITION o ne f a ct fertilization of ja n d) ig In the growing of legume crops such as clover, alfalfa, peas or beans for the t he The Necessity of of Roots of Legumes prime importance. The legume bacteria must be in the soil. Unless there are nodules on the roots, the crop has no fertilizing power. It does not enrich and may actually impoverish the soil. No no- dules will be borne on the roots unless the particular species of nitrogen-fix- ing bacteria adapted to the particular plant is in the soil. There is no one species of bacteria capable of working with all the leguminous plants. The clover bacteria do not work with soy- beans. The bacteria of sweet clover and alfalfa do not form nodules on the roots of peas. Among agricultural plants there are recognized six groups of legumes, each Classification depending upon a distinct of Legumes species of bacteria. These (1) Alfalfa, groups are Sweet Clover and Burr Clover, (2) the true clovers, Red, Alsike, White Dutch and Crimson, (3) Soy Bean, (4) Cow Pea, Jap Clover, Lima Bean and Velvet Bean, (5) Garden and Field Bean, (6) Garden and Field Pea, and Vetch. Even if grown not as a fertilizer but as a forage crop, the legumes are not depended upon un- Need of t he Proper bacteria Proper Bacteria l e ss are present in sufficient number to adequately supply the plant with nitrogen. There is always a pos- sibility that crop failure may be due to the absence of nodule bacteria. The plant may be starving, even with its yellowing leaves bathed in the element which it craves. True, this is not always the case, for the legume may get nitrogen from the . ^ T h at soil, as do other crops. On very rich soil a fair crop of legumes may be pro- duced even if there are few legume bacteria present. In this case the seem- ingly satisfactory crop would be mak- ing no addition to the wealth of the soil, but instead would diminish it. The only way to judge of the success of a fertilizing crop is by observing the quantity of nodules on the roots. There follows a natural question. May it not be possible to supply the nitrogen-fixing bacteria 0 .1T Soil Inoculation t o t h|g o i l? this may be done without difficulty has been conclusively established, both by scientific experiment and by actual practice on the farm. The process is called "soil-inoculation." In early experimentation bacteria were placed in sterile soil by leaching. In 1887 the inoculation of field-soil was first attempted at Bremen, Germany. The land used was reclaimed swamp which had never produced leguminous vegetation. It was treated by being sown broadcast with soil taken from a legume-bearing field, 350 pounds to the acre. A vigorous growth resulted, whereas similar land not so treated produced oyly small and yellow plants. But the use of legume-bearing earth as an inoculating material was found fth ka ve ^s disadvantages Pure°Cukure as ^ involved much labor and, too often, the intro- duction of weeds and plant diseases. Inoculation is now made by means of a pure culture, that is, an uncontami- nated growth of one kind of nodule- producing bacteria. This growth is ob- tained by removing the bacteria from nodules and transferring them to a sterile solution in which they are free to multiply. Bacterial cultures were first pre- pared on a commercial scale and in Germany in s o ld T h ey however, Failure of Gelatin 1 8 96 , As a Medium proved a disappoint- ment, largely owing to the unsuitable character of the medium in which the bacteria were grown. This medium was a gelatin, already so rich in nitrogen that the growth of the bacteria was discouraged. Also a process called plasmolysis was likely to take place, that is, the medium being denser than the protoplasm of the cell, the mois- ture of the cell flowed out into the me- dium, causing the death of the bacteria. Discredit was thus cast upon the use of pure cultures. Eventually the study of pure-culture methods was undertaken by the United States Department of Agriculture. European methods seemingly having J\. . failed, attempts were made along new lines. The need for this undertaking was particularly felt owing to the in- troduction into this country of two Asi- atic legumes, alfalfa and soy beans. In the first propagation of soy beans it had been found necessary to import humus material from Japan to supply the plants with their characteristic nodule-forming bacteria. Soil for the raising of alfalfa, it was found, could be inoculated with humus from old al- falfa or sweet clover fields. Inocula- tion by such means, however, always had its disadvantages and a pure-cul- ture method was greatly desired. ^ „ In 1905 the Bureau of Plant Industry produced the so-called "cotton cul- rpU g^ ture," a m e t h od The Cotton Culture Good in Theory Only which, it was at first supposed, had solved all difficulties. Pieces of absorbent cot- ton were moistened in a liquid culture and dried. This cotton was supposed to be placed by the user in a liquid salt which would provide a medium in which the bacteria would rapidly mul- tiply. The method, however, did not work out in practice. There was al- ways danger of contamination of the culture by bacteria and moulds from the air and, moreover, the drying of the cotton had already destroyed a large part of the desired bacteria. Thus such cultures failed to produce satisfactory results. Various other methods of distribu- tion have been tried. Notable among these are the dried cul- Other Methods tures w h i ch were tried out by the U. S. Depart- ment of Agriculture and the cultures on "agar" which were used by the On- tario Agricultural College, Guelph, Canada. The latter method gave fairly satisfactory results if the fresh cul- tures were used. Others evolving the use of liquid or humus as a medium were eventually produced and are used today with a considerable degree of success. A dry medium fails to supply moisture to the bacteria, which, as be- fore stated, is of vital importance. A dry humus is certain to lower the vital- ity and shorten the life of the bacteria. T he m o st thoroughly successful method, and one which is now widely o ^ a nd satisfactorily used, Sand the Sue- cessfui Medium w a s perfected a f e w years ago. This is the method used exclusively in the prepa- ration of Scott's bacteria. The medium in which the bacteria are colonized is sterilized sand of a very fine texture, to which is added water and various nutrient substances. The advantages of the sand medium is that it absorbs the poisons given off by the bacteria, , •» * o * » which, in other types of culture, such as humus and gelatin, accumulate and destroy the bacterial life. Sand per- mits the growth of more bacteria per ounce and per unit volume than humus and the vitality of the organism is re- tained for a longer time. If humus is used as a medium the organic content is apt to permit the development of other bacteria and fungi. The sand used is first sterilized by heat, thus rendering it impossible for plant dis- eases or weeds to be transmitted. This culture, as sold, is efficient during the entire season for which it is made, and even longer. The general advantages of Scott's bacteria are that the cultures contain c , a particularly large num- Superiority of , ^ Scott's Culture t>er of bacteria, r e t a in their efficiency for a long time and are economical to use. The cultures are sold in packages at one dollar each, postage paid. For all small seeded legumes, one culture suf- fices for thirty pounds of seed, while for large seeds like soy beans, one cul- ture is sufficient for sixty pounds of seed. If soy beans are planted with corn, one culture is enough for six acres, and the cost of inoculation is less than seventeen cents per acre. The method of applying the culture to the seed is simple. The seed is first * , , . .. . , spread on a clean floor ^M} ïo _ 1 Memou oi Method of placed in a tub. The cultu^r Application Placed is then poured from the con- tainer into a clean vessel, one container of water added for clover or vetch, or two for beans or peas, and the culture stirred thoroughly. The mixture is then sprinkled over the seed, which is stirred with the hand or a rake until each seed is slightly moistened. The bacteria will adhere to the seed. When the seed is dry it is sown in the usual way. The efficiency and value of soil-in- oculation with the pure culture has been abundantly demonstrated both by experiment and practical use. Experiments with soy beans at the New Hampshire Experiment Station in 1917 showed that in- Results of oculated seed yielded Some Experiment 7.2 tons green weight Station Tests per acre, while unin- oculated seed yielded only 4.7 tons. In Ohio it was shown that seeds of inocu- lated plants contained 42.47 per cent protein and the uninoculated only 35.26 per cent protein. Nitrogen is the prin- cipal constituent of protein, hence the more nitrogen a plant contains, the richer it is in protein and the more val- uable feed. Inoculation causes legumes to have a larger nitrogen content. At the C a n a d i an Experimental Farms in 1909 an inoculated field pro- duced per acre 2,560 pounds of cured alfalfa. A similar inoculated field pro- duced 7,200 pounds. At the Alabama Experiment Station an acre of hairy vetch, uninoculated, p r o d u c ed 900 pounds of green forage. A similar acre, inoculated, p r o d u c ed 9,136 pounds. In Minnesota it was found that an acre of uninoculated sweet clover produced 11 pounds of nitrogen per acre, while a similar acre, inocu- lated, produced 128 pounds. At the Illinois Experiment Station it was found that the tops of cowpeas which had not been inoculated con- tained 2.48 per cent of nitrogen, while the inoculated had 4.24 per cent. The inoculated plants contained about twice as much dry matter as the plants not inoculated. From such experiments it is safe to draw the conclusion:—It is unwise to attempt to grow leguminous crops for either forage or fertilization without suitably inoculating the soil. O. M. SCOTT & SONS CO. Marysville, Ohio ROGERS & HAUL CO.. PRINTERS. CHICAGO