652 3 •py 1 UNIVERSITY OF SOUTHERN CALIFORNIA PUBLICATIONS Volu LOS ANGELES, CALIFORNIA MARCH 1915 Number 1 NITRATING THE SOIL BY INOCULATED LEGUMES Baileg UNIVERSITY OF SOUTHERN CALIFORNIA PUBLICATIONS Volume 2 LOS ANGELES, CALIFORNIA MARCH 1915 Number 1 NITRATING THE SOIL BY INOCULATED LEGUMES BY GILBERT ELLIS BAILEY, A.M., PH.D. Professor of Geology Copyright 1915, by Gilbert Ellis Bailey All Rights Reserved Printed by the University of Southern California Press 3474 University Avenue, Los Angeles / MAR 30 1915 (0)CI,A:iiV8 142 FOREWORD Agriculture is no longer simply a method of getting a liv- ing, but is a real business enterprise managed and controlled with scientific accuracy and all engaged in it are ever hunt- ing for new secrets of success. This paper has been prepared partially to answer numerous inquiries impossible to answer by mail, but mainly to call attention again to one of the duties everyone who tills the soil owes to the Nation, and in that sense it is an appeal to patriotism. The intention is to be practical rather than technical, for the man engaged in farming wants to know the points of practical value in a positive or negative way. No claim of originality is, nor can be, made in work of this kind, but some of the authorities consulted are referred to by num- ber for the benefit of those who wish to study some points more fully. All know that the soils of Palestine, which once flowed with milk and honey, are now a barren waste. Everyone realizes that the fertility of soils ought not to be reduced; that high civilization cannot be maintained unless there is an abundance of food products. Many know that NITRO- GEN is the most expensive and difficult plant food there is to get, especially at the present time when nitrate of soda is contraband of war. Some know that Nature has a remedy for the deficiency; that it is possible to obtain unlimited supplies of NITROGEN from the air at small cost, by means of inoculating legumes with nitrogen bacteria. Success with nitrogen bacteria is a simple and not difficult combination of science and sense and calls for only moderate thoughtfulness and care. Inoculation of soils has already passed the experimental stage and is established as an agricultural necessity. Farming without the aid of bacteria would be an impossibility for the soil would yield no crops. 4 University of Southern California The soil is the support of agriculture, and agriculture is the support of the nation. It is evident, therefore, that an in- telligent control of the beneficial bacteria is a matter of National importance. The wealth of a State lies in her soil, and her strength lies in its intelligent cultivation. The final destiny of America in fact rests upon the question whether the producing power of the soil shall be reduced, maintained, or increased; and this productiveness must not be temporary but perma- nent. The great sciences of physics, chemistry, geology, and bac- teriology are the servants of agriculture standing, as it were, with bared arms ready to serve our present and future needs. Agriculture is coming to be a scientific pursuit, and farming is now recognized as a learned profession. The successful farmer of tomorrow will be the one who knows how to han- dle most skillfully the micro-organisms in the soil. The imperfect methods of the past led to waste, and the culminating point of success in the future can only be reached under the most capable management. The brain farmer is slowly but surely crowding out the muscle farmer; for work and knowledge are a stronger team than work and work. The rate of progress is still too slow for there is scarcely an area in the world that is producing for man the quantity of food that it should. In the last ten years our population has increased 21 per cent, while the acreage of farm lands increased less than 5 per cent; and the average production per acre is far below that of European countries. Increased population has led to increased demands with- out an increased source of supply. The increased value of farm lands makes it necessary to get more out of the soil than ever before, yet the ten year average of wheat in the United States is only 14 bushels per acre. Compare this to the 29 bushels of wheat per acre raised in the older soil of Germany; the 33 bushels raised in Great Britain; and the more than 40 bushels raised in Denmark. (46.) Americans waste plant food. We do not return what we take from the soil. If we keep drawing from our capital. Nitrating the Soils 5 without making deposits from time to time, our drafts will not be perpetually'honored. The merchant sells and buys again keeping up his stock; the farmer sells, and sells, and sells, until he is practically gold out. The parable of the talents is as significant now as when it was uttered; and to us are given talents never given before. The fate of the Nation lies in the progressive farmers who do not bury their talents but keep them alive; the men whose public spirit, patience, and watchful care maintain the fertility of the soil. , ^' KEEP UP THE FERTILITY%TtHE SOIL! Do not leave your children with only a mernory or a tradition of the bountiful harvests of former times. The owner should in- crease the fertility of his land for his children's sake; the tenant should leave the farm better than he found it If he who "makes two blades of 'grass grow where one grew before is a benefactor," then he who reduces the fertility of the soil is a public curse. For the sake of humanity, for the sake of our own nation see that the land does not grow poorer but richer from year to year. THE BACTERIA All organic matter, that is all dead animal and vegetable material, begins to decompose, decay, or rot as soon as it is buried in the soil. This is Nature's method of sanitation, and of keeping per- fect the cycles of life. Everything is at once taken apart and each part made ready to use over again. (31.) This work is done by various kinds of bacteria, each hav- ing its specific task to perform. There are two varieties present in all soils, to a greater or less extent, whose work it is to separate the nitrogen from the complex organic com- pounds which are useless for plant food. One variety con- verts the nitrogen into nitrites, and the other converts these into soluble nitrates; a form that can be used by plants as food. U. S. Dept. Agriculture. COWPEA TUBERCLES Nitrating the Soils There is a still more valuable kind of bacteria that possess the peculiar and most valuable power of TAKING NITRO- GEN FROM THE AIR AND NODULE BACTERIA CONVERTING IT INTO NI- TRATES, ready for use by the plant as food. These bacteria live in nodules on the roots of leugmes, and are generally known as the nitrogen bacteria. (1, 5.) U. S. Dept. Agriculture. Roots of Red Clover Showing Nodules They are single-celled organisms somewhat closely allied to the yeast plant; and are as harmless to man, beast, or plant, as the yeast germ itself. They are classified as plants but are on the border line between the animal and vegetable kingdom where any strict division must be a purely arbitrary one. Analysis shows that they are about 80 per cent water; tlie ash con- 8 University of Southern California sisting largely of phosphoric acid, with notable quantities of potash and lime; while there are only traces of sulphur, iron, magnesium, and silica. (8, 6, 14, 36, 37, 38,) In method of reproduction they are classed with the schizomycetes, or fission fungi, for they multiply by elongat- ing a little and then dividing into two equal halves; each half soon growing to mature size, ready in turn to divide. They are so minute that 25,000 of them would only make a line an inch long, and they must be magnified from 600 to 1200 times before the human eye can see them. The germ comes to maturity in 20 minutes and then divides, so that in 40 minutes there are four young germs that in 20 minutes more will be eight; and in a week billions will be in existence. This rate of growth is of course not maintained, but is checked by lack of food, by the substances they secrete, by temperature, and many other causes; yet they exist in num- bers beyond human comprehension, as a single nodule may contain more thousands of inhabitants than our largest cities. They grow and do their work in perfect darkness and are killed almost instantly when exposed to the full action of the sun's rays. This is due to the actinic and not to the heat rays. While they are easy to kill in some ways, in others they are very resistant, going into a spore or hibernating condi- tion which serves to tide the species over a period of dryness, famine, or unsuitable temperature, and to preserve alive in a hostile environment a sufficient number of individuals until favorable conditions return. (22, 1, 5, 4, 34, 55.) Hellriegel and Wilfarth in 1886 showed that the tubercles were associated with the assimilation of free nitrogen (30, 7) and since then the life history of the germs HISTORICAL has been worked out by scores of scientists such as Atwater in America; Lawes and Gilbert in England; Boussingault, Ville, Pasteur, Schlossing, and Muntz of France; Nobbe in Germany, and Winogradsky of Russia. Their work has been verified at Agricultural Experiment Stations all over the world, and the farmer can Nitrating the Soils 9 now utilize this method -of obtaining nitrogen, feeling that he is not experimenting, but using established, facts and well-known truths. (21, 13, 3, 7, 30, 18.) Legumes, such as soy beans, cow peas, vetch, alfalfa, etc., form a plant partnership with the nitrogen bacteria that is of immeasurable value to agriculture. PLANT PARTNERS It is not a parasitic relationship where one of the plants is injured while the other is benefiited; but it is one of mutual helpful- ness. The legume furnishes the home for the bacteria, and in its sap, or juice, most of the nourishment upon which the bacteria live. The bacteria gain entrance to the roots of Seed not Inoculated Courtesy Armour Fertilizer Works RED CLOVER Seed Inoculated with "Nitragin" legumes through the hair roots, causing a very definite tis- sue reaction at the point of invasion. Once having gained entrance they confer upon the plant immunity from other bacteria, as only bacteria of higher virulence than those in the nodules are able to enter the roots. (1,5,22.) 10 University of Southern California The nodule, or tubercle, found on the roots of legumes is the home of the bacteria somewhat as the ball on the willow- twig is the home of the insects within. THE NODULES The -nodule itself is an expansion, or excessive growth of the cells of the legume root, and varies in size from a pinhead to a pea ac- cording to the legume it grows upon. During the early stages of growth long thread-like sacs, or tubes, force their way through the root cells, and the bacteria live in these sacs. The nodules are home fertilizer factories where the bac- teria take the nitrogen from the air and convert it into solu- ble nitrates which pass at once into the plant circulation. It is the air IN the soil which the bacteria use, not the air above the soil, and the accumulation of nitrogen takes place first of all inside the nodule. It is evident, therefore, that the soil must be porous so that the air can get down to the root hairs, or the bacteria will have no nitrogen to work on. (30, 7, 9, 14, 22.) The permanence of the bacterial life is most important and the farmer should note carefully the things that affect their continued existence in his soil. While LONGEVITY they multiply rapidly, and die with almost equal rapidity, permitting the host plant to profit by the nitrogen they kave combined into nitrates; yet they are after all very persistent and maintain their con- tinued existence against great odds. There is only a scanty growth of the germs unless free oxygen is present, hence the soil must be deeply aerated. Since they feed during their growth they are affected by the food the plant feeds on, as well as effecting profound changes in the material upon which they feed. The soil must, therefore, be adapted to the host plant or the sap will not stimulate the growth of the germ. The bacteria are live, sensitive plants, requiring free oxygen and easily destroyed if contaminated with filth, and are, therefore, injured by some forms of organic matter such as .too fresh manure, and highly concentrated decomposing masses. (30, 27, 10.) Nitrating the Soils 1 1 The nodules are windowless little houses and the bac- teria live and work in darkness while unlocking the soil nit- rogen, and are easily destroyed by light. Inoculated seed should be kept in the dark until used, and protected from sun- light as far as possible while planting. A drought will not kill the nitrogen bacteria but renders them inactive for the time, and thus diminishes the percent of nitrogen gained; and a continued drought makes it diffi- cult to revive the germs from a dried condition. (19, 26.) Every organism, animal or vegetable, has what is known as its optimum, or best, temperature at which point it is most vigorous; and each has its maximum and minimum temperature at which its characteristic activities cease. The Seed not Inoculated Courtesy Armour Fertilizer Works COW PEAS Seed Inoculated with "Nitragin" optimum temperature for the nitrogen bacteria is 36.6° C, or 98° F; although nitrification may proceed in a measure from 4.4° C, or 40° F to 54.4° C, or 130° F. (12.) The lowering of the temperature affects the bacterial activity, yet they survive winter freezing, remaining dormant in their little nodule houses; but their activities are of no importance be- yond keeping the species alive. (41.) This is an advantage as no soluble nitrates are produced to be lost by the leach- ing of the spring rains. Bad soil conditions, and a lack of potash and phosphorous for the host plant may starve the bacteria into a degen- erative stage of branched and vacuolated forms that do not grow or form colonies. (19,20,27.) C^ y-*^ 12 University of Southern California Science does not yet know what different species there may- be among the nitrogen bacteria, but it does know that there are different types or varieties each adapted VARIETIES to its particular legume. Cow peas demand one variety, soy beans another, alfalfa still another, and so on. Courtesy Armour Fertilizer Works ALFALFA Seed Inoculated Seed not with "Nitragin" Inoculated Varieties adapted to one legume may be unable to produce nodules on another species, and germs that were very active when associated with one species of plant may refuse to Nitrating the Soils 1 3 form nodules on the roots of a closely allied species. (54, 22.) By selecting legumes having vigorous growths of tubercles many of the most useful varieties have been segregated and the breeding of pure germs has PURE BRED BACTERIA become a business, a science, and as much of an economic necessity as the breeding of high-grade cattle. The high-bred germs are more vigorous, and therefore more resistant to drought, and other unfavorable conditions. Courtesy Armour Fertilizer Works ALFALFA Seed not Seed Inoculated Inoculated with "Nitragin" They give the quickest and shortest road to success and it is always wisest to depend upon pure cultures for inocu- lating the seed. Most soils are not naturally supplied with the nitrogen bacteria; and there are other soils in which they are already present but not in sufficient quantities, NOT PRESENT or of good grade. It is like a man hav- IN MOST SOILS ing some mongrel range cattle on his ranch. He must invest in blooded stock in order to bring his ranch up to th.e grade necessary for making the most money. The clover bacteria were not orig- inally found in Illinois soils, causing a failure of red clover under otherwise normal conditions. Alfalfa was pro- nounced a failure for years in Illinois because there were no alfalfa bacteria naturally in the soil; but the crop is now a success wherever the bacteria have been introduced. The 14 University of Southern California soy bean bacteria did not exist in Connecticut soils and had to be introduced; and the investigations made in many other states give additional illustration of this fact. (53, 54, 49.) Only such plants as develop tubercles are able to increase the amount of nitrogen in their tissues. No leguminous plant is able of itself to secure nitrogen NO NODULES, from the air, but each legume must be NO NITROGEN provided with the particular variety of bacteria which has the power to live upon its roots and gather nitrogen from the soil atmosphere. The marked effect of inoculation is seen on the growth, color, and composition of the plant even though only half a dozen large nodules form on the roots. The greater the number of the nodules the better the growth. Plants with- out nodules show no increase; those with a moderate num- ber show a slight increase; while those with abundant tubercles grow luxuriously and show the largest increase in nitrogen. (23, 19,20.) There is no time when plants are so susceptible to injury by unfavorable soil conditions as in the early period of their growth. Plants sprout readily and for THE NITROGEN a short time grow, vigorously, then the HUNGER STAGE vigorous growth ceases and the plant seems to be suffering for lack of food. This is the nitrogen hunger stage, a period in which the plant not inoculated has used up all the nitrogen in its seed; and unless the seed was inoculated the baby roots have to begin searching through the soil in all directions for the nitrogen the plant must have. In the meantime the top growth has to wait and starve until the supply has been found and the nitro- gen begins to come to the plant. The uninoculated plant leads a struggling existence until supplies of soluble nitrogen have been found in the soil. If the seed has been inoculated, as soon as it sprouts and the roots begin to grow the bacteria begin to supply the nitrogen which the baby plant at once assimilates, giving a vigorous growth from the start, and abso- lute protection from the nitrogen hunger. (53, 46.) Nitrating the Soils 15 THE SOIL Primitive methods have led to the belief in lack of soil fertility. The record of the human race in the past has been one of ruined lands, in Palestine, in southern FERTILITY Europe, in Russia, and in the eastern part of the United States. The slogan of the present is increase the fertility of the soil. We must not be satisfied with a temporary system of agriculture in which the available food steadily decreases; but we must demand a permanent system in which all the available plant food is perpetually maintained. It will not do to drift with the tide waiting for something to turn up. We must be alert to seize every discovery of science and utilize it. We must know the inner mysteries of the soil as we know the inner mysteries of plant life. Soil fertility is the crop producing power of a soil, under the best conditions; and this fertility depends largely upon three factors: first and most important, the physical charac- ter: second, the bacteriological character: and last the chem- ical composition. The soil has two functions; first, it furnishes a home, a mere lodging place for the plant in which it lives and moves and has its being; second, it furnishes food for the nourish- ment, growth, development, and maturing of the plant. If the physical condition of the soil is poor, or the chemical composition unusual, no amount of inoculation will pro- duce crops equal to those grown on fertile soils. Maintain- ing the fertility of the soil means that there shall be pre- served within the soil sufficient amounts of soluble plant food of the various kinds necessary to produce maximum crops. The growing of inoculated legumes is absolutely es- sential for maintaining the nitrogen supply, and necessary as a part of any economic system which shall maintain the fertility of the soil; of any system that will make a poor soil fertile, and keep a good soil fertile. (54, 26, 17, 39, 6.) U. S. Dept. Agriculture. Hairy Vetch and Rye Growing Together Nitrating the Soils 1 7 The absolute essentials in the growing of crops are: I, the seed; 2, the soil, or home and lodging place; 3, the food; 4, the drink, or moisture; 5, ABSOLUTE ESSENTIALS the heat; 6, the light; 7, free- dom from weeds; 8, freedom from disease. Any one of these factors may limit the yield of crop. Poor seed is poor economy. Proper soil conditions are as essen- tial to the life and activity of the bacteria as they are to the growth of the plant. The inoculation of the seed is only one step towards suc- cess, and no matter how carefully carried out, will fail if the other things just as essential are not looked after. Each type of soil is specially adapted to specific crops and this adaptation should be closely studied. There should be reason and moderation in all CROP ADAPTATION things. Some want to grow alfalfa and other crops on soils not adapted to them, by applying bacteria, and then complain of lack of success. Such ideas, and such practice are not a part of intelligent farming. The quantity of active nitrogen furnished the plant de- pends more upon the physical condition of the soil than on its nature and corhposition. Nitrification is a AERATION process of oxidation as well as combining nitrogen, and the soil must contain oxygen. As all the nitrogen obtained must come from the air in the soil, the soil must be porous so that the atmosphere may penetrate it. The deeper the air penetrates the soil the deeper the nodules will be found and the greater the quantity of nitrogen obtained. Thorough cultivation of the soil and DEEP PLOWING are necessary to thoroughly aerate it. This aeration also reduces in number certain other kinds of soil bacteria that are inimical to the nitrification process. (19,42,6.) 18 Universii'^ of Southern California The number of bacteria in a soil is closely related to the moisture conditions, and even slight differences in the amount and kind of moisture present may read- MOISTURE ily cause differences in crop production and in bacterial activity. The soil must not be too wet, or water-logged; and it must not be too dry. There should be a good supply of water vapor and film, or hygroscopic water, maintained by good capillary conditions. If the voids are filled with water the air cannot penetrate the soil. The root hairs feed in the films of moisture clinging to the soil particles, and this supply is kept replenished by capillary action drawing up water from below. (19,20, 11.) The number of bacteria in soils decreases as the temperature is lowered, being practically at a minimum when the soil is frozen. When the soil temperature does TEMPERATURE, not go far below the freezing point the mineral matter in the film water may keep it from freezing and bacteria may multiply to some extent, keeping the species alive without hibernation. Thor- ough cultivation of the soil admits air, warming the soil as well as draining off excess water. The great difficulty in cultivation is that plows and other implements do not go deep enough. This has led to the introduction of plowless agriculture, or loosening up the soil by means of explosives. As nearly all legumes will send their roots very deep if per- mitted by the soil conditions the use of explosives is of special benefit when inoculating with nitrogen bacteria. (7, 12, 6.) The use of explosives sets free plant food; plows deep without mixing the subsoil with the top soil; admits oxygen of the atmosphere to the organic matter THE USE OF in the soil hastening decomposition; ad- EXPLOSIVES mits nitrogen of the atmosphere to the roots, promoting bacterial nitrification; makes all the soil available by fining it; breaks up hard pan; makes a reservoir for water; warms and dries the soil; saves the rain by taking it into the soil; prevents evap- Nitrating the Soils 19 oration and conserves moisture; permits the roots to go deep down into the soil; makes the moisture of the subsoil available; makes the plant food in the subsoil available; and converts subsoil into fertile soil, deepening the feeding zone of the roots. (74.) PLANT FOODS Crops are not made out of nothing but are built up from food elements just as a building is made of wood, iron, brick, stone and mortar; for without materials nothing material can be made. A few simple facts should be kept in mind, viz: that 95 per cent of most plants consist of carbon, hydrogen, and oxygen; and that the remainder consists mainly of nitrogen, potassium, and phosphorous; with minute quantities of iron, lime, magnesium, silica, etc. There is no market value to the carbon which the plant inhales through its leaves; or to the hydrogen and oxygen which they obtain from water; or NO MARKET VALUE to the calcium, magnesium, iron and sulphur because only minute amounts are required and because they are practically present in ALL SOILS in sufficient quantities for plant growth. There is a high market value to nitrogen, potash, and phosphorous because all plants re- A MARKET VALUE quire considerable quantities, and they are naturally present in soils in rather limited quantities. Plants require balanced rations as much as cattle, and adding nitrogen to a plant starv- BALANCED RATIONS ing for potash or phosphorous will do no good and only tends to still further unbalance the food supply. 20 University of Southern California Potash is obtained largely from the mineral deposits of potassium salts, from wood ashes, and should also be obtained from the inexhaustible supplies of sea FOOD SOURCES kelp. Phosphorous is obtained from rock phosphates, slag phosphates, bone meal, etc. Small quantities of nitrogen oxides are formed by electrical discharges through the air and are washed down by the rains. Organic nitrogen exists united with carbon, hydrogen, oxygen and other elements in the form of partially decayed vegetable and animal matter, but is insoluble in that form and unavailable for plant food. It is contained in ammonium salts, in dried blood, and .cottonseed meal, and other sources. The principal source, however, has been sodium nitrate, also known as niter, and Chili saltpeter, the main supply coming from the deserts of Taramaqual in Chili. Sodium nitrate contains 15 to 16 per cent of nitrogen; am- monium sulfate 20 to 21, and dried blood 12 to 15 per cent. The manufacture of calcium nitrate by uniting atmos- pheric nitrogen with lime by means of powerful electrical discharges was started abroad a few years ago, but this supply is now shut off by the war. The cost is excessive and no farmer can afford to purchase a pound for general farming. Only market gardeners who take off several crops of high DISADVANTAGES OF market value a year, or those MINERAL NITRATES raising special crops like oranges and lemons can afford to use the commercial forms of nitrogen fertilizers. Mineral nitrates are easily lost because they are very solu- ble, and if left in the soil in the fall or formed during the winter may be largely lost before spring by percolating waters unless the land is covered by a crop that will take them up. It is often difificult and expensive to apply them at just the proper time, when the plant, tree, or crop needs them most. U. S. Dept. Agriculture. Roots of Peanut Vine, Showing the Value of this Plant as a Nitrogen Gatherer. The Nodules on the Roots are formed by the Bacteria which collect the Nitrogen. 22 University of Southern California Very large quantities of nitrate of soda are necessary to bring crops, from barley to oranges, upon a par with those supplied by legumes. The crop uses only the nitrogen and does not need the soda, and the continued use of nitrate of soda may have an in- jurious effect on the soil, even to producing an alkali condi- tion. With mineral nitrates one does not get the benefit of added humus and organic matter as when the legumes arc plowed under and decompose in the soil. (49, 42, 45.) Nitrogen is removed frorrnthe soil not only by crops grown, and by drainage waters, but also by the blowing oflf of the surface soil; and by the action of denitrifying germs, and the losses this way may be several times the amount used by the crops. If any question pertaining to the science and practice of agriculture is settled it is this — that the atmosphere is the most economical source of nitrogen NITROGEN FROM for all general farming. THE AIR The atmosphere consists of a mixture — not a combination — of 79 volumes of nitrogen to 21 of oxygen; or by weight, 77 per cent of nitrogen to 23 of oxygen. In the air nitrogen is inert, combining with nothing, and only serving to dilute the oxygen. The atmosphere gives an inexhaustible supply, for all that is drawn from it returns again in the cycles of plant and ani- mal life. It has been estimated that if the population of the earth was 1000 million it would take 3800 years for their respiration to use up one per cent of the oxygen of the air. if none was returned in the meantime; and there is about four times as much nitrogen to draw from as there is oxygen. There are about 75 million pounds of nitrogen resting on every acre of soil, pressing down upon it nearly 15 pounds per square inch, or more than a ton to the square foot. The air over each acre of land contains sufficient nitrogen for a hundred bushel crop of corn every year for 40,000 years; and owing to the cycle of life from soil to plant, from plant to animal, and from animal back to the soil, the supply is per- Nitrating the Soils 23 manent. This free and inexhaustible supply cannot be used by any plants except legumes, and they cannot use it unless the nitrogen gathering bacteria are present. (54, 50, 23, 25, 34, 42, 55.) U. S. Dept. Agriculture. Roots of Soy Beans, Showing Nodules Varro wrote before the Christian era that lupines were plowed into a poor soil in lieu of manure; but agriculture has had to wait for centuries to know why THE LEGUMES and how the lupines fertilized the soil. All plants which bear their seed in a capsule or pod, such as clover, alfalfa, peas, beans, vetch, peanuts, etc., are known as legumes. The legume itself has no power to fix nitrogen. This power rests wholly with the bacteria in the nodules on the 24 University of Southern California roots of the legume, which do have the power to take the free nitrogen from the air and unite it with othe' elements forming nitrates which are dissolved in *b(: juices of the legume. The farmer secures the presence of these bacteria by in- oculating the seeds of the legume before planting them. A legume that has no. bacteria nodules is a soil robber, for inoculated legumes grow just the same as other plants and must get their nitrogen from the soil the same as non- leguminous plants. Each legume must have its own particular variety of bac- teria. In fact one of the most dominant causes of failure or unsatisfactory growth of some of the most valuable legumes is the absence of the proper nitrogen gathering bacteria. Today the farmer can get all the germs he wants and sow them with the legume seed, thus taking a most important step towards insuring a perfect stand and stocking the soil with nitrogen. It is easy to see if the bacteria are present, for all that one has to do is to pull up a few plants and see if the nodules are there on the roots. Where the plants are sparsely infected the individual nodules develop to an enormous size, but few in number. Where the soil is well infected the individual nodules are much smaller and more numerous. Legumes are deep rooted plants and require thorough and deep tillage of the soil. This increases their value to the farmer for it carries nitrification deep down, fertilizing the soil to depths that no other method can. As the legumes approach maturity the nitrogen is largely absorbed from the tubercles and stored in the tops and roots of the host plant; then if the legumes are plowed under all this nitrogen, together with millions of the germs are distributed in the soil. They should be plowed under before the crop fully matures so that thorough decomposition may quickly occur. (53, 54, 49, 2, 4, 28, 33, 57, 59.) Nitrating the Soils 25 Nitrogen bacteria cannot live in an acid medium and are absent from acid soils. The decay of leaves and the decom- position of organic matter usu- NONE IN ACID SOIL ally produces acids that kill oflf the little workers and put an end to their usefulness. Even soils which overlie limestone may be acid in their first foot or two. The soil should be tested with litmus, or other reagents, to be sure that it is not acid. (1,5.) There is a class of bacteria that are denitrifiers setting soil nitrogen free again. They do not live in nodules, but are abundant in manure heaps and in all DENITRIFIERS de(composing heaps, and jdimimsh rap- idly when the manure is well rotted. Only well-rotted manure should be used where legumes are planted, and then only in limited quantities. Denitrifying germs are particularly active in soils carrying a limited amount of air, and in water-logged soils. These facts again emphasize the necessity for thoroughly and deeply culti- vating the soil. (1, 5.) If no alkaline element like lime, potash, or magnesium is present in the soil no nitrate can be formed. The lime sup- plies the base for uniting with the LIME NECESSARY nitrogen and oxygen in forming the soluble nitrates. Its presence is necessary also to neutralize any acid in the soil. Old air slacked lime, fine ground limestone, and marl are the most economical forms to use. Fresh burned lime, or fresh slacked lime are not advisable as they tend to attack and destroy the organic matter in the soil, or "burn the land." Fifty-six pounds of lime will furnish 74 pounds of perfectly dry slaked lime. The amounts required vary widely accord- ing to local conditions. In some soils 1000 pounds of lime- stone per acre is ample, in others three tons per acre are required. Lime helps to conserve the moisture and aid in carrying the bacteria through a period of drought. It is also of indi- 26 Univefsiiy of Southern California rect benefit in unlocking potash and phosphorous that are present in the soil but unavailable. (54, 19, 49, 29, 32, 56, 75.) All soils are not adapted to the same legumes. One soil may be specially adapted to beans, producing a large crop, developing quantities of nodules and fix- VARIETIES OF ing an abundance of nitrogen, yet the LEGUMES same soil may not support alfalfa or other species of legumes nearly as well. Fortunately there are a large number of legumes that have been bred to a high state of perfection, together with their specific bacteria, giving an assortment covering nearly every peculiarity of soil and climate. Alfalfa, the queen of forage plants, is a muscle-building feed, while corn is a fattening and heating feed, and to- gether they make an excellent ration for any animal on the farm. Alfalfa roots go down to great depths, 12 to 20 feet being common; while 65 feet has been noted in California. This deep rooting habit enables it to stand drought, and is of special value because large quantities of mineral plant food are brought up from the depths. (40,44,47.) There is a world-wide demand for Peas and Beans as food for the human race, and they can also be readily converted into milk, pork, mutton, beef, and other cash money prod- ucts. (58, 60.) The Cowpea and the Soy Bean will grow upon land too poor to grow anything else. They are used in the rotation of crops to maintain fertility; and as a supplementary feed to balance other rations in feeding animals. They may be sown with grain and corn or used after oats as a fertilizer or catch crop, or as an orchard cover crop cultivated during the season and then pastured of? with hogs. Inoculated cowpeas contained 4.09 to 4.33 per cent of nitrogen jn their tops and 1.42 to 1.53 per cent in the roots, while those not infected contained only 2.32 to 2.69 per cent in the tops and .88 in the roots. (54, 35, 48, 51, 61, 62, 64, 72.) It is often difificult to get at catch of Clover on new land be- cause its bacteria are not present in the soil, but a good catch or stand is secured if the clover seed is inoculated. Nitrating the Soils 11 Clovers make potash and phosphoric acid in the soil available; protect the soils from blowing and washing; change loose sand into a compact loam with greater mosture holding capac- ity; tind make stifif clays more open and friable, allowing better aeration. They make good cover crops for fields in the winter, from corn to cotton. (15,16,63,66,71,73.) % fc ^ V t^J tf""^j^ i A ^^ / . 1 -«»^T'- ! "if,' ^^ ' ^ w am ^ '^'v! ■ '"'"'■■J^i^- -^' t-i" i \ '^^^^M U. S. Dept. Agriculture. Peanuts Growing in the Alleys Between Rows of Corn The common, or summer vetch is extensively used on the Pacific coast and in the southern states as a winter hay crop being sown with oats, rye, or wheat; and in the citrus groves as a winter green manure crop. The winter, or hairy vetch is more resistant to cold than any other annual legume grown. It is used as a green manure and cover crop on tobacco lands and in orchards. (69, 70.) The lupines make a rank growth and are exten- 28 University of Southern California ively used in Germany for putting humus and nitrogen into sandy soils. The sanfoin, or esparsette is similar to the clovers in some respects. It may be sown with any of the grains as a Hurse crop, and later cut for hay or turned under for humus and nitrogen. One of the most valuable annuals is the serra- della as it remains green under the snow in winter, giving winter pasture. It is also valuable for recovering sandy wastes, for cover and nurse crop, for feeding stock, and as a green manure being plowed under in the spring to be fol- lowed by potatoes, corn, or cereals. Nitrogen germs will not develop on the roots of non-legu- minous crops and it is useless to inoculate their seed. They must be furnished with nitrogen by NON-LEGUMINOUS the legumes. Cowpeas, crimson CROPS clover, vetch, etc., are inoculated and planted between the rows of corn or cotton, and plowed under after the harvest. The clovers, sainfoin, serradella, etc., are often sown with wheat, oats, rye and other cereals, and the whole crop is sometimes turned under as a green manure. Alfalfa, clover, vetches are inoculated and planted between the rows of orchards and small fruits and plowed under for the humus and nitrogen. Some legumes, like the black-eyed bean, peanuts, etc, are made a source of income while the young orchard is grow- ing. Legumes do not make a sod difficult to work and may be planted ahead of crops such as hops, cotton, tobacco, as- paragus, potatoes, and grain, or in fact of any crop that needs nitrogen. The benefits derived from inoculating legume seed with the nitrogen bacteria are threefold: 1, it increases the crop; 2, it increases the food value of the crop; 3, it BENEFITS increases the fertility of the soil. Evidence on these points is readily obtained from any of the many agricultural stations. It is well known that inoculated crops sprout quicker, grow faster, have a darker, richer green color, and larger blossoms. Bacterial nitrogen is better dis- tributed through the soil than mineral or organic nitrogen. Nitrating the Soils 29 and two tons of clover or cowpeas plowed under may have greater power to liberate plant food than 20 tons of old, inactive matter in the soil. Bacteria can put from 150 to 200 pounds of available nitrogen in each acre, where the legumes are properly used; and this is worth from $25 to $30 per acre according to the market value of nitrates. In New Jersey the increase in dry matter by inoculation was, for alfalfa 500 per cent; beans 75 per cent; while cowpeas more than doubled. (24.25.) The University of Illinois says: By proper inocula- tion we have grown a crop of alfalfa which contained as high as 17 times the quantity of nitrogen as was contained in a crop grown without inoculation but otherwise under exactly the same conditions. (52.) The same authority says $1 of lime made more than a $10 increase per acre in alfalfa hay, and $4 of phosphorus made an additional increase of hay, while the presence or absence of alfalfa bacteria made the crop a success or failure respectively. (50.) Canada field peas inoculated by pure culture supplied more than seven times the amount of nitrogen furnished by those not inocu- lated. The increase in corn in Iowa was from 52 to 68 bushels, and in oats from 33 to 55 bushels. (19) In Alabama the inoculation increased the yield of hairy vetch 89 per cent, of Canada field peas 138 per cent, and of crimson clover 146 per cent. (2.) In Arkansas, legumes were grown and turned under on cotton land and corn land with the following results: Cowpeas gave 1335 pounds of seed cotton per acre; soy beans gave 1448 pounds; and velvet beans gave 1550 pounds of seed cotton; the corn land§ gave with the cowpea 37 bushels per acre; and with the soy beans 42 bushels of corn per acre. (4.) Protein is the general name for a series of organic com- pounds that contain nitrogen in addition to oxygen, carbon and hydrogen. One group consists of the INCREASE IN final nitrogenous organic compounds called PROTEIN PROTEIDS, which constitute the FLESH, (not the fat) and VITAL ORGANS of animals, and the protein of mature plants. The number of proteids is very large, and all contain nitrogen, usually about 30 University) of Southern California 16 per cent, and some of them also contain phosphorous and sulfur. The high cost of living is already calling attention to the special value of peas and beans, as they contain as much protein as meat, and the best way to insure this supply is by inoculating the seed. The more protein there is in the crop, the more beef it makes when fed to stock. Soils are never so rich but that their quality may be im- proved, or so poor but that they may be made to produce good crops. Where there is a de- BENEFIT TO THE SOIL ficiency of humus or decompos- ing organic matter in the soil a green manure crop of inoculated legumes should be plowed un- der, increasing the fertility of the soil; increasing the yield and food value of succeeding crops; restoring fertility to land that now produces little or nothing; and by stocking the soil with nitrogen increasing the CASH VALUE OF THE FARM. The masses of the fine roots of the legumes penetrate and hold the soil together during the heavy winter rains and prevent surface washing, saving the fertile top soil. They also regulate the moisture supply, and modify the ill effects of extreme temperature. They keep the soil in good physical condition, the turned under legumes binding together loose sandy soils, loosening up stiff clay soils, and making loams loose and friable. They are a safeguard against injury to fruit at harvest time. They insure against the wearing out of the soil. Plants not only secrete food but excrete waste material, poisoning the soil with these toxins, and finally checking their own growth. Some crops are not in- CROP ROTATION jured by the toxins left by preced- ing crops in the soil; other crops are injured; and a few thrive. The secret of successful crop rotation lies in selecting a crop that will remove or neutralize the toxins left by the preceding crop. The object of rotation is to preserve the fertility of the soil; to maintain its good physical condition; and to put back ALL the plant food re- moved from it. Nitrating the Soils 31 It helps to maintain the organic matter in the soil, and is aided by the use of all farm manures, and a liberal use of green manures. Rotation, however, is not enough, as for example in Ohio a five years' rotation of corn, wheat, clover and timothy did net secure sufficient nitrogen for maximum crops. The rotation must contain legumes. It is not assumed that the bacteria can replace other plant foods, or do away with the proper cultivation of the soil; but inoculation with the nitrogen bacteria is the secret of success in sticcessful crop rotation. Courtesy Armour Fertilizer Works SOY BEANS Seed inoculation is not a new discovery, and there is noth- ing mysterious about it. It is admitted by all authorities that it can be successfully performed by any NO MYSTERY careful farmer who will take the neces- sary time and pains. IT IS NOT A CURE-ALL, and no sensible man will claim it as such; it does not take the place of potash or phosphorous; sweeten sour or acid soils; or remove the necessity of thorough culti- vation; but it can double the yield of crops where all the other conditions given are favorable. 32 University of Southern California The best method is to inoculate the seed by treating it with a proper culture of the special germ adapted to the legume before planting. The most sci- INOCULATE THE SEED entific method is to obtain a pure culture, for specialists have succeeded in breeding strong, healthy, vigorous germs which can be sent by mail to the farms and orchards; and are as clearly an economic necessity as pure-bred cattle or pure-bred sugar beets. The cultures should be fresh, as they then contain a larger number of active organisms and are better for inoculating than old cultures. Use only the best seed, and get them free from weeds. Poor seed is worse than none at all; and bacteria are not weed killers. Follow the directions of the parties you buy the germs from, only seeing that the seed is thoroughly wet; and then spread it out to dry where it will not mould or sprout, or lose its vitality by exposure to sunlight; or be subject to any of the conditions mentioned that weaken or destroy the bac- teria. Remember especially that the bacteria are minute, delicate plants that live and work in the dark, and should no more be exposed to direct sunshine than a photograph plate. They should be mixed with the seed when the sun is not shining, or in the evening; and should be planted mornings and evenings, unless the sky is clouded. Be sure of your dealer, as it has been found in a few instances that some cultures did not contain the nodule-forming germ at all, a mistake easily made by anyone not a specialist, as there are soil bacteria that produce colonies VERY SIMILAR in appearance to the tubercle-forming ones. (15, 26, 23.) Tubercle-forming bacteria will disappear from some soils in a few years if the legume upon which they grow is not grown occasionally; while in other soils PERMANENCE they seem to remain, becoming nor- mally present. Bacteria growing in soil richly stocked with organic nitrogen lose much of their power to fix new nitrogen, and the nodules seem to dwindle away Nitrating the Soils 33 and lose their peculiar function, seeming to follow the gen- eral law that unused organs suffer atrophy. Inoculation is a benefit wherever nitrogen is needed in the soil; where the soil has not previously borne legume crops; TNOCTIT ATTON wherever the legumes previously grown AN ADVANTAGE showed only a few nodules, or a weak growth of crop; where the legumes to be grown belong to a species not closely related to the one previously grown on the same soil. If you have bad spots in a field, take good, sweet, inoculated soil from the same field, and never from some other field, and spread it on the bad spots. Every teacher knows that it is easier to teach 20 men what is good to do than to persuade one man to do it. Be the one man in your district to do the right CONTROLLING thing, and that is to find out for LOCAL CONDITIONS yourself if there is any deficiency of any element in your soil; and to prove the benefit of all new material by means of test plats. TEST PLATS ARE A NECESSITY ON EVERY FARM; and are far better than any analysis, chemical or physical. They give the prudent method and the cheap- est method of checking results. The one-twentieth of an acre is a handy size. Plant one plot with the legume with- out using any germs or fertilizer of any kind; on another plant the legume and use inoculated seed, without using potash and phosphorus; on another use inoculated seed and potash and phosphorous. Each plot should be treated with lime to neutralize any acidity in the soil. Be careful that water from the inoculated ground does not drain onto plats not inoculated and thus make comparison impossible. When full grown cut an equal area from each plat and weigh each separately and compare; but do not trust the eye alone, as a 25 per cent increase may not show unless you weigh. Dig samples of roots from each plot, going deep enough to get the entire roots; wash carefully until the roots are white; 34 University of Southern California put the bunches of roots into separate glasses and let the roots float apart, noting the form, size and number of the nodules. Each nodule means so much nitrogen for the land. Do the work carefully, as the nodules strip ofiF easily and may be lost, especially where small but numerous. Normally, seasonal and climatic conditions vary, and changes in local temperatures and in moisture are constant and one must make allowance for them in his methods of cul- tivation. Use test plots for checking seed, crops, fertilizers, and dififerent methods of cultivation on your own soil. Inves- tigations of local peculiarities are not experiments but invest- ments, a guide towards success, and a protection against loss. Trifles noted may give success, and SUCCESS IS NO TRIFLE. Test and know with your own knowledge before condemning anything new in agriculture. The dangers of inoculation by soil transfers are not imag- inary but clearly established at many of the state experiment stations, and it is now considered SOIL TRANSFERS folly to try such a haphazard method. It may, and has, transferred plant diseases, noxious weeds, and insect pests. The cost of trans- ferring 400 to 500 pounds per acre from one locality to an- other is large, and the task is laborious. Many bacteria are killed by the sunshine during the transfer, and the germs are often weak and lack strength to penetrate the roots of the legumes. The inoculation with pure cultures leads to better results. (30.) Success is a matter of brain, not brawn. Have faith in the investigations at experiment stations and do not condemn the principle, but study the methods that PRECAUTIONS lead to success. The dealer can only guarantee the purity and vigor of his bacteria, he cannot force the farmer to guard himself against failure caused by not closely observing the other factors of success. Most failures come from neglect to follow directions. Do not open the cultures until ready to use. Use them only for-the crop and acreage as directed. Sow the treated seed as Nitrating the Soils 35 soon as possible. Do not try to keep some over for future use, as they drj' out, and a too long dried condition reduces vigor. Use fresh vigorous cultures, and keep the germs in a cool, clean, dark place such as a cellar. Do not let treated seed come in contact with commercial fertilizers. Do not spread seed in the sun to dry. Do not plant the seed' when the sun is very bright, or hot. Plant on a rainy or cloudy day, or in the morning or evening. Do not use on an acid soil, but neutralize first with lime. See that the soil contains enough potash and phosphorous. See that the soil is well aerated, well drained, and warm. See that the crop is adapted to your soil, and your local climatic conditions. See that foul grass and weeds are kept out. Do not leave things to your hired help. Success lies in yourself, for to him that hath gumption big crops shall be given. REFERENCES. 1. Agricultural Bacteriology. Lyon & Fippin. Macmillan. 1909. 2. Alabama Agr. Exp. Sta. — Southern burr clover. Bull. 165. 3. Archives des Sciences biologiques, Vol. III. 4. Arkansas Agr. Exp. Sta. Legume manuring. Bull. 58. 5. Bacteriology. Jordan. Saunders Co. 1908. 6. California Soils. Bailey. Lmiv. S. Calif. Press. 1914. 7. Centralbl. f. Bakt. 1887. 8. Centralbl. f. Bakt. 1897. 9. Centralbl. f. Bakt. 1900. 10. Centralbl. f. Bakt. 1904. 11. Centralbl. f. Bakt. 1909. 12. Centralbl. f. Bakt. 1910. 13. Chimie Vegetale et Agricole. — Berthelot. 14. Delaware Agr. Exp. Sta. Tubercle bacteria. Bull. 73. 14. Delaware Agr. Exp. Sta. Tubercle bacteria. Bull. 78. 15. Delaware Agr. Exp. Sta. Crimson clover. Bull. 86. 16. Delaware Agr. Exp. Sta. Crimson clover. Bull. 89. 17. Dry farming. Widtsoe. Macmillan. 1913. 18. Hellriegel — "LTntersuchungen uber die Stickstoffnahrung der Gramineen und Leguminosen.'' — Zeitscher, des Vereins fur Rubenzuckerin- dustrie .d, D. R. Nov. 1888. 19. Iowa Agr. Exp. Sta. — Soil bacteriology. Bull. 4. 20. Iowa Agr. Exp. Sta. — Soil bacteriology. Bull. 5. 21. Maze. — "Fixation d I'azote libre par le bacille des nodosites de legumineuses. Inst. Pasteur. Vol. I. 0897. 22. System der Bakterien. Jena. 1897. Migula. 23. Michigan Agr. Coll. — Bacterial activity in the soil. Bull. 16. 36 University of Southern California 24. New Jersey Agr. Exp. Sta. Nitrate of soda on crops. Bull. 16. 25. New Jersey Agr. Exp. Sta. Atmospheric nitrogen in the soil. Bull. 180. 26. Oklahoma Agr. Exp. Sta. — Soil inoculation. Bull. 68. 27. Oklahoma Agr. Exp. Sta. — Soil inoculation. Bull. 69. 28. Oregon Agr. Coll. — Green manure crops. Bull. 120. 29. Ohio Agr. Exp. Sta. — Liming the soil. Bull. 159. 30. Pesn. State Coll. x\gr. Exp. Sta. — Commercial cultures for legumes. Bull. 78. 31. Rettger— Jour. Biol. Chem. 1908. -4. 32. Rhode Island Agr. Exp. Sta. — Lime, nitrogen and soda. Bull. 47. 33. Rhode Island Agr. Exp. Sta. — Legumes. Bull. 49. 34. Rhode Island Agr. Exp. Sta. — The nitrogen problem. Bull. 50. 35. Rhode Island Agr. Exp. Sta. — The soy bean. Bull. 92. 36. Soils. Hilgard. Macmillan. 1911. 37. Soils. Fletcher. Doubleday. 1910. 38. Soil Fertility. Hopkins. Ginn Co. 1910. 39. Soil Management. Lyon & Fippin. Macmillan. 1909. 40. South Dakota Agr. Exp. Sta.— Alfalfa. Bull. 94. 41. Studien uber de Bakterienorfla des Ackerbodens, etc. Berlin. 1903. 42. Texas Agr. Exp. Sta. — Active nitrogen in the soil. Bull. 7. 43. Univ. Calif. Agr. Exp. Sta. Annual Report. 1913-1914. 44. Univ. Calif. Agr. Exp. Sta. Alfalfa. Circular 87. 45. Univ. Illinois Agr. Exp. Sta. — Commercial fertilizers. Circular 129. 46. Univ. Illinois Agr. Exp. Sta. — Plant food and ^oil fertility. Circular 155. 47. Univ. Illinois Agr. Exp. Sta. — Alfalfa. .Circular 4. 48. Univ. Illinois Agr. Exp. Sta. — Cowpea and soybean. Circular 5. 49. Univ. Illinois Agr. Exp. Sta. — Soil investigations. Circular 64. 50. Univ. Illinois Agr. Exp. Sta. — Soil investigations. Circular 68. 51. Univ. Illinois Agr. Exp. Sta. — Cowpea and soy bean. Circular 69. 52. Univ. Illinois Agr. Exp. Sta. — Soil investigations. Circular 72. 53. Univ. Illinois Agr. Exp. Sta. — Inoculation of legumes. Circular 86. 54. Univ. Illinois Agr. Exp. Sta. — Nitrogen bacteria and legumes. Bull. 94. f 55. Univ. Wisconsin Agr. Exp. Sta. — Nitrates in soils. Bull. 85. 56. U. S. Dept. Agr. Farmers' Bull. — Liming of soils. No. 77. 57. U. S. Dept. Agr. Farmers' Bull. — -Beans and other legumes. 121. 58. LT. S. Dept. Agr. Farmers' Bull.- — Canadian field peas. 224. 59. v. S. Dept. Agr. Farmers' Bull.- — Leguminous crops for manuring. 278. 60. U. S. Dept. Agr. Farmers' Bull. — Beans. 289. 61. U. S. Dept. Agr. Farmers' Bull. — Cowpeas and soy beans. 309. 62. v. S. Dept. Agr. Farmers' Bull.— Cowpeas. 318. 63. U. S. Dept. Agr. Farmers' Bull. — Clover farming. 323. 64. U. S. Dept. Agr. Farmers' Btill.- — Soy beans. 372. 65. U. S. Dept. Agr. Farmers' Bull. — The peanut. 431. 66. U. S. Dept. Agr. Farmers' Bull. — Red clover. 455. 67. U. S. Dept. Agr. Farmers' Bull. — Sweet clover. 485 68. U. S. Dept. Agr. Farmers' Bull. — Forage crops for cotton. 509. 69. U. S. Dept. Agr. Farmers' Bull.— Vetches. 515. 70. U. S. Dept. Agr. Farmers' Bull. — Vetch growing. 529. 71. LT. S. Dept. Agr. Farmers' Bull. — Crimson clover. 550. 72. U. S. Dept. Agr. Farmers' Bull. — Cowpeas. 559. 73. v. S. Dept. Agr. Farmers' Bull. — Crimson clover. 579. 74. Univ. S. Calif. — Use of explosives in agriculture. Bull. 7. 1913. 75. LTtah Agr. Coll. — Nitrogen fixation. Bull. 114. -tmmm ^irmmH' 1 ^iT^^a Photographed Feb. 24th, 1915 Courtesy Armour Fertilizer Works Corn Stimulated with Inoculated Beans Corn not Stimulated Common Vetch 16 days old LIBRARY OF CONGRESS ^^H0002 756 632 7 TB -