DRY-FARMING: A SYSTEM OF AGRICULTURE FOR COUNTRIES UNDER A LOW RAINFALL TEXT

independent of the composition of the seed or the nature of the soil, but depends primarily upon the prevailing climatic conditions, including the water supply. The weight of the wheat per bushel, that is, the average size and weight of the wheat kernel, and also the hardness or flinty character of the kernels, were strongly affected by the varying climatic conditions. It is generally true that dry-farm grain weighs more per bushel than grain grown under humid conditions; hardness usually accompanies a high protein content and is therefore characteristic of dry-farm wheat. These notable lessons teach the futility of bringing in new seed from far distant places in the hope that better and larger crops may be secured. The conditions under which growth occurs determine chiefly the nature of the crop. It is a common experience in the West that farmers who do not understand this principle send to the Middle West for seed corn, with the result that great crops of stalks and leaves with no ears are obtained. The only safe rule for the dry-farmer to follow is to use seed which has been grown for many years under dry-farm conditions. A reason for variation in composition It is possible to suggest a reason for the high protein content of dry-farm crops. It is well known that all plants secure most of their nitrogen early in the growing period. From the nitrogen, protein is formed, and all young plants are, therefore, very rich in protein. As the plant becomes older, little more protein is added, but more and more carbon is taken from the air to form the fats, starches, sugars, and other non-nitrogenous substances. Consequently, the proportion or percentage of protein becomes smaller as the plant becomes older. The impelling purpose of the plant is to produce seed. Whenever the water supply begins to give out, or the season shortens in any other way, the plant immediately begins to ripen. Now, the essential effect of dry-farm conditions is to shorten the season; the comparatively young plants, yet rich in protein, begin to produce seed; and at harvest, seed, and leaves, and stalks are rich in the flesh-and blood-forming element of plants. In more humid countries plants delay the time of seed production and thus enable the plants to store up more carbon and thus reduce the percent of protein. The short growing season, induced by the shortness of water, is undoubtedly the main reason for the higher protein content and consequently higher nutritive value of all dry-farm crops. Nutritive value of dry-farm hay, straw, and flour All the parts of dry-farm crops are highly nutritious. This needs to be more clearly understood by the dry-farmers. Dry-farm hay, for instance, because of its high protein content, may be fed with crops not so rich in this element, thereby making a larger profit for the farmer. Dry-farm straw often has the feeding value of good hay, as has been demonstrated by analyses and by feeding tests conducted in times of hay scarcity. Especially is the header straw of high feeding value, for it represents the upper and more nutritious ends of the stalks. Dry-farm straw, therefore, should be carefully kept and fed to animals instead of being scattered over the ground or even burned as is too often the case. Only few feeding experiments having in view the relative feeding value of dry-farm crops have as yet been made, but the few on record agree in showing the superior value of dry-farm crops, whether fed singly or in combination. The differences in the chemical composition of plants and plant products induced by differences in the water-supply and climatic environment appear in the manufactured products, such as flour, bran, and shorts. Flour made from Fife wheat grown on the dry-farms of Utah contained practically 16 per cent of protein, while flour made from Fife wheat grown in Lorraine and the Middle West is reported by the Maine Station as containing from 13.03 to 13.75 per cent of protein. Flour made from Blue Stem wheat grown on the Utah dry-farms contained 15.52 per cent of protein; from the same variety grown in Maine and in the Middle West 11.69 and 11.51 per cent of protein respectively. The moist and dry gluten, the gliadin and the glutenin, all of which make possible the best and most nourishing kinds of bread, are present in largest quantity and best proportion in flours made from wheats grown under typical dry-farm conditions. The by-products of the milling process, likewise, are rich in nutritive elements. Future Needs It has already been pointed out that there is a growing tendency to purchase food materials on the basis of composition. New discoveries in the domains of plant composition and animal nutrition and the improved methods of rapid and accurate valuation will accelerate this tendency. Even now, manufacturers of food products print on cartons and in advertising matter quality reasons for the superior food values of certain articles. At least one firm produces two parallel sets of its manufactured foods, one for the man who does hard physical labor, and the other for the brain worker. Quality, as related to the needs of the body, whether of beast or man, is rapidly becoming the first question in judging any food material. The present era of high prices makes this matter even more important. In view of this condition and tendency, the fact that dry-farm products are unusually rich in the most valuable nutritive materials is of tremendous importance to the development of dry-farming. The small average yields of dry-farm crops do not look so small when it is known that they command higher prices per pound in competition with the larger crops of more humid climates. More elaborate investigations should be undertaken to determine the quality of crops grown in different dry-farm districts. As far as possible each section, great or small, should confine itself to the growing of a variety of each crop yielding well and possessing the highest nutritive value. In that manner each section of the great dry-farm territory would soon come to stand for some dependable special quality that would compel a first-class market. Further, the superior feeding value of dry-farm products should be thoroughly advertised among the consumers in order to create a demand on the markets for a quality valuation. A few years of such systematic honest work would do much to improve the financial basis of dry-farming. CHAPER XIV MAINTAINING THE SOIL FERTILITY All plants when carefully burned leave a portion of ash, ranging widely in quantity, averaging about 5 per cent, and often exceeding 10 per cent of the dry weight of the plant. This plant ash represents inorganic substances taken from the soil by the roots. In addition, the nitrogen of plants, averaging about 2 per cent and often amounting to 4 per cent, which, in burning, passes off in gaseous form, is also usually taken from the soil by the plant roots. A comparatively large quantity of the plant is, therefore, drawn directly from the soil. Among the ash ingredients are many which are taken up by the plant simply because they are present in the soil; others, on the other hand, as has been shown by numerous classical investigations, are indispensable to plant growth. If any one of these indispensable ash ingredients be absent, it is impossible for a plant to mature on such a soil. In fact, it is pretty well established that, providing the physical conditions and the water supply are satisfactory, the fertility of a soil depends largely upon the amount of available ash ingredients, or plant-food. A clear distinction must be made between the_ total _and _available _plant-food. The essential plant-foods often occur in insoluble combinations, valueless to plants; only the plant-foods that are soluble in the soil-water or in the juices of plant roots are of value to plants. It is true that practically all soils contain all the indispensable plant-foods; it is also true, however, that in most soils they are present, as available plant-foods, in comparatively small quantities. When crops are removed from the land year after year, without any return being made, it naturally follows that under ordinary conditions the amount of available plant-food is diminished, with a strong probability of a corresponding diminution in crop-producing power. In fact, the soils of many of the older countries have been permanently injured by continuous cropping, with nothing returned, practiced through centuries. Even in many of the younger states, continuous cropping to wheat or other crops for a generation or less has resulted in a large decrease in the crop yield. Practice and experiment have shown that such diminishing fertility may be retarded or wholly avoided, first, by so working or cultivating the soil as to set free much of the insoluble plant-food and, secondly, by returning to the soil all or part of the plant-food taken away. The recent development of the commercial fertilizer industry is a response to this truth. It may be said that, so far as the agricultural soils of the world are now known, only three of the essential plant-foods are likely to be absent, namely, potash, phosphoric acid, and nitrogen; of these, by far the most important is nitrogen. The whole question of maintaining the supply of plant-foods in the soil concerns itself in the main with the supply of these three substances. The persistent fertility of dry-farms In recent years, numerous farmers and some investigators have stated that under dry-farm conditions the fertility of soils is not impaired by cropping without manuring. This view has been taken because of the well-known fact that in localities where dry-farming has been practiced on the same soils from twenty-five to forty-five years, without the addition of manures, the average crop yield has not only failed to diminish, but in most cases has increased. In fact, it is the almost unanimous testimony of the oldest dry-farmers of the United States, operating under a rainfall from twelve to twenty inches, that the crop yields have increased as the cultural methods have been perfected. If any adverse effect of the steady removal of plant-foods has occurred, it has been wholly overshadowed by other factors. The older dry-farms in Utah, for instance, which are among the oldest of the country, have never been manured, yet are yielding better to-day than they did a generation ago. Strangely enough, this is not true of the irrigated farms, operating under like soil and climatic conditions. This behavior of crop production under dry-farm conditions has led to the belief that the question of soil fertility is not an important one to dry-farmers. Nevertheless, if our present theories of plant nutrition are correct, it is also true that, if continuous cropping is practiced on our dry-farm soils without some form of manuring, the time must come when the productive power of the soils will be injured and the only recourse of the farmer will be to return to the soils some of the plant-food taken from it. The view that soil fertility is not diminished by dry-farming appears at first sight to be strengthened by the results obtained by investigators who have made determinations of the actual plant-food in soils that have long been dry-farmed. The sparsely settled condition of the dry-farm territory furnishes as yet an excellent opportunity to compare virgin and dry-farmed lands and which frequently may be found side by side in even the older dry-farm sections. Stewart found that Utah dry-farm soils, cultivated for fifteen to forty years and never manured, were in many cases richer in nitrogen than neighboring virgin lands. Bradley found that the soils of the great dry-farm wheat belt of Eastern Oregon contained, after having been farmed for a quarter of a century, practically as much nitrogen as the adjoining virgin lands. These determinations were made to a depth of eighteen inches. Alway and Trumbull, on the other hand, found in a soil from Indian Head, Saskatchewan, that in twenty-five years of cultivation the total amount of nitrogen had been reduced about one third, though the alternation of fallow and crop, commonly practiced in dry-farming, did not show a greater loss of soil nitrogen than other methods of cultivation. It must be kept in mind that the soil of Indian Head contains from two to three times as much nitrogen as is ordinarily found in the soils of the Great Plains and from three to four times as much as is found in the soils of the Great Basin and the High Plateaus. It may be assumed, therefore, that the Indian Head soil was peculiarly liable to nitrogen losses. Headden, in an investigation of the nitrogen content of Colorado soils, has come to the conclusion that arid conditions, like those of Colorado, favor the direct accumulation of nitrogen in soils. All in all, the undiminished crop yield and the composition of the cultivated fields lead to the belief that soil-fertility problems under dry-farm conditions are widely different from the old well-known problems under humid conditions. Reasons for dry-farming fertility It is not really difficult to understand why the yields and, apparently, the fertility of dry-farms have continued to increase during the period of recorded dry-farm history--nearly half a century. First, the intrinsic fertility of arid as compared with humid soils is very high. (See Chapter V.) The production and removal of many successive bountiful crops would not have as marked an effect on arid as on humid soils, for both yield and composition change more slowly on fertile soils. The natural extraordinarily high fertility of dry-farm soils explains, therefore, primarily and chiefly, the increasing yields on dry-farm soils that receive proper cultivation. The intrinsic fertility of arid soils is not alone sufficient to explain the increase in plant-food which undoubtedly occurs in the upper foot or two of cultivated dry-farm lands. In seeking a suitable explanation of this phenomenon it must be recalled that the proportion of available plant-food in arid soils is very uniform to great depths, and that plants grown under proper dry-farm conditions are deep rooted and gather much nourishment from the lower soil layers. As a consequence, the drain of a heavy crop does not fall upon the upper few feet as is usually the case in humid soils. The dry-farmer has several farms, one upon the other, which permit even improper methods of farming to go on longer than would be the case on shallower soils. The great depth of arid soils further permits the storage of rain and snow water, as has been explained in previous chapters, to depths of from ten to fifteen feet. As the growing season proceeds, this water is gradually drawn towards the surface, and with it much of the plant-food dissolved by the water in the lower soil layers. This process repeated year after year results in a concentration in the upper soil layers of fertility normally distributed in the soil to the full depth reach by the soil-moisture. At certain seasons, especially in the fall, this concentration may be detected with greatest certainty. In general, the same action occurs in virgin lands, but the methods of dry-farm cultivation and cropping which permit a deeper penetration of the natural precipitation and a freer movement of the soil-water result in a larger quantity of plant-food reaching the upper two or three feet from the lower soil depths. Such concentration near the surface, when it is not excessive, favors the production of increased yields of crops. The characteristic high fertility and great depth of arid soils are probably the two main factors explaining the apparent increase of the fertility of dry-farms under a system of agriculture which does not include the practice of manuring. Yet, there are other conditions that contribute largely to the result. For instance, every cultural method accepted in dry-farming, such as deep plowing, fallowing, and frequent cultivation, enables the weathering forces to act upon the soil particles. Especially is it made easy for the air to enter the soil. Under such conditions, the plant-food unavailable to plants because of its insoluble condition is liberated and made available. The practice of dry-farming is of itself more conducive to such accumulation of available plant food than are the methods of humid agriculture. Further, the annual yield of any crop under conditions of dry-farming is smaller than under conditions of high rainfall. Less fertility is, therefore, removed by each crop and a given amount of available fertility is sufficient to produce a large number of crops without showing signs of deficiency. The comparatively small annual yield of dry-farm crops is emphasized in view of the common practice of summer fallowing, which means that the land is cropped only every other year or possibly two years out of three. Under such conditions the yield in any one year is cut in two to give an annual yield. The use of the header wherever possible in harvesting dry-farm grain also aids materially in maintaining soil fertility. By means of the header only the heads of the grain are clipped off: the stalks are left standing. In the fall, usually, this stubble is plowed under and gradually decays. In the earlier dry-farm days farmers feared that under conditions of low rainfall, the stubble or straw plowed under would not decay, but would leave the soil in a loose dry condition unfavorable for the growth of plants. During the last fifteen years it has been abundantly demonstrated that if the correct methods of dry farming are followed, so that a fair balance of water is always found in the soil, even in the fall, the heavy, thick header stubble may be plowed into the soil with the certainty that it will decay and thus enrich the soil. The header stubble contains a very large proportion of the nitrogen that the crop has taken from the soil and more than half of the potash and phosphoric acid. Plowing under the header stubble returns all this material to the soil. Moreover, the bulk of the stubble is carbon taken from the air. This decays, forming various acid substances which act on the soil grains to set free the fertility which they contain. At the end of the process of decay humus is formed, which is not only a storehouse of plant-food, but effective in maintaining a good physical condition of the soil. The introduction of the header in dry-farming was one of the big steps in making the practice certain and profitable. Finally, it must be admitted that there are a great many more or less poorly understood or unknown forces at work in all soils which aid in the maintenance of soil-fertility. Chief among these are the low forms of life known as bacteria. Many of these, under favorable conditions, appear to have the power of liberating food from the insoluble soil grains. Others have the power when settled on the roots of leguminous or pod-bearing plants to fix nitrogen from the air and convert it into a form suitable for the need of plants. In recent years it has been found that other forms of bacteria, the best known of which is azotobacter, have the power of gathering nitrogen from the air and combining it for the plant needs without the presence of leguminous plants. These nitrogen-gathering bacteria utilize for their life processes the organic matter in the soil, such as the decaying header stubble, and at the same time enrich the soil by the addition of combined nitrogen. Now, it so happens that these important bacteria require a soil somewhat rich in lime, well aerated and fairly dry and warm. These conditions are all met on the vast majority of our dry-farm soils, under the system of culture outlined in this volume. Hall maintains that to the activity of these bacteria must be ascribed the large quantities of nitrogen found in many virgin soils and probably the final explanation of the