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Forty million acres devoted to it; an annual crop of seventy million tons, valued at something like three-quarters of a billion dollars. Such is the record of hay in the United States. And of course this takes no account of the other millions of acres that are devoted to pasturage, the crop of which would be hay if it were not harvested directly by browsing live stock. Just how much this would add to the value of the crop it is difficult to say. But without attempting an exact computation, it will be clear that the value of forage crops in America reaches a colossal figure. There are many kinds of grass that may be found first and last in pasture and hay-field, but the one grass that over-shadows all others because of its universal popularity is that known as timothy in most regions, and in some regions as herd's grass. It may be of interest to recall that each name is merely borrowed from the name of the man who was instrumental in introducing this particular grass; one man being Timothy Hanson or Hanse, of Maryland, who is said to have brought the seed from England in 1720; the other being John Herd, who is alleged to have found the grass growing wild in a swamp in New Hampshire as early as 1700. One of these men distributed the grass through Virginia and Carolina, the other through New England and New York. From these regions it has spread in every direction, proving adaptable to all climates and soils, until it assumes pre-eminence in the pasture and hay-field quite unchallenged except by members of the clover family, with which it is commonly associated. The clovers, to be sure, are not grasses in the technical sense of the word. Nor, indeed, have they the appearance of grasses even to the eye of the most casual observer. But they rival the grasses in their importance as fodder plants. In certain regards, as for instance in the amount of protein they bear, they outrival the grasses. Also in their capacity to produce successive crops in the same season, some of the clovers, notably the more recently introduced alfalfa, are superior to the grasses proper. But in general clover and timothy are mixed to form the hay-crop, the clover growing densely near the ground, and the timothy rising above it, and the two making a blend that is found exceedingly palatable by all herbivorous animals. The fragrance of new mown hay suggests palatability to the human senses as well, and even though the hay-crop furnishes food for man only at second hand no one would be likely to question its wholesomeness.


There are certain of the clovers, nevertheless, that have a poisonous principle. Notable among these is a form of sweet clover not distantly related to the alfalfa, which grows in some of the States of the Middle West and produces an enormous crop which would have great value were it not that unfortunately the tissues of the plant contain a considerable percentage of a bitter alkaloid called brucine, which is highly poisonous, being closely related to the well-known drug strychnine. A few years ago I received from Kansas samples of this plant, with the request that I develop from it a variety in which the brucine is reduced to a minimum, or, if possible, wholly removed. The seeds that I received were of various colors. My first move was to have the seeds sorted, placing white ones, black ones, and green and brown by themselves. The seeds were then planted in separate lots; a fifth lot being reserved for a mixture of the seeds of uncertain shades. Thus it was possible at the outset to determine whether the production of plants having a large brucine content was associated with any particular color of seeds. Should such be found to be the case, the experiment would obviously be shortened, as only the plant bearing the minimum amount of brucine would be used for further testing. Experiments showed that the plants from the white seed apparently contained an appreciably less quantity of brucine than the black ones. As an additional element in the selection, I chose, as is my custom, the seed plants that started very early in the Spring. From among these the next selection was made of the plants that had broad foliage and continued to make a very strong growth. Thus several objects were attained almost from the outset. A second selection along the same lines showed that some plants have a much smaller brucine content than others, and that it will be quite possible to separate these out and thus produce a variety relatively free from poison. Some similar experiments in improving peas, beans, and other plants related to the clovers, gave assurance that I should be successful in the present instance, merely by selective breeding, in producing a plant with relatively low brucine content, and the experiments even in their initial stages justify this belief. Whether it may be necessary to resort to hybridizing experiments in order to eliminate the brucine altogether or to reduce it to a negligible minimum, remains to be seen. The experiments were begun only in 1910. It should be explained that the hybridizing of the plants of this group is relatively difficult, because the flowers are encased in a closed receptacle, as with the peas and beans, which belong to the same family with the clovers. All of these so-called leguminous plants-and they are outnumbered only by the composite flowers-bear the stamens and pistils thus guarded, and are normally self-fertilized. As already pointed out, this makes the experiment of hand-pollenizing these plants a rather tedious one. In the case of the clovers, the flowers being very small, it becomes a somewhat delicate operation as well. But the later stages of the experiment are greatly facilitated bly the fact that the flowers are self-fertilized. With these plants, as with the small grains, this becomes an important aid in fixing a type, and in maintaining a pure race once it has been developed. For the most part, my experiments with the clovers have been made through selection, and without resort to hybridization. But in exceptional cases I have cross pollenated these plant to test the possibilities of work in this line. I found that the process involves no great difficulties, notwithstanding the small size of the flowers. In practice I found it better to remove all but two or three flowers in a clover head. The remaining ones have the petals and stamens removed with a small pair of forceps, after which the application of pollen from another clover head presents no special difficulties; care being taken, of course, to see that the pistil is at the right stage of development.


In the course of these experiments I have grown in the neighborhood of two hundred species of clover. Many of these are native species, some of which invaded my grounds unasked. Others have been received from far away regions, in particular from Peru, Bolivia, and Chile. Whereas the white clover in its common native forms is a relatively small plant, dwarfed beside the red and crimson clovers, there are South American species or sub-species that are of relatively gigantic growth. One of these that I received from South America was a seeming "sport"-possibly due to an accidental hybridizing with some other species-that grew several times as fast as any of the others in a lot of seedlings. A single plant of this giant variety would spread from four to six feet, the foliage being proportionately enlarged, while a neighboring plant would perhaps grow ten to fifteen inches. Selection among these rapid growers enabled me to develop several varieties that had the characteristic of growing to quite uncloverlike size. But there is no sale for new clovers unless the seed can be furnished by the ton, and as I had no opportunity to produce seed on a large scale, the giant races were ignored, when they had ceased to interest me from an experimental standpoint. I worked for a number of years also upon a clover that, without having exceptional qualities of stem, produced very large foliage. In this case also the development was made solely by selection, the largest leafed individuals of a fraternity being selected for preservation generation after generation. In the same way I produced a five-leafed strain of clover from a sport that appeared among plants of the usual three-leafed type of white Dutch clover. The four-leaved clover is of course well-known as an occasional sport. A five-leafed clover will appear in a lot of seedlings now and again, and there will be found a few five-leafed individuals among the plants grown from seed of this sport. It would, however, require many repetitions, seemingly, to fix a five-leafed race, the tendency to reversion to the familiar three-leafed type being very pronounced. Whether the five-leafed condition acts as a Mendelian unit character, is a matter that might be of some interest to determine. Another anomaly consisted of a clover with leaves beautifully colored-variegated in black, brown, crimson, scarlet, yellow, white and green, in different forms and figures, no two plants being closely similar in the coloring of the leaves. This plant was introduced as a new variety, but it did not thrive in the Eastern States and has probably been allowed to die out altogether. I have another stock of this which came from chance seedlings, but in no respect equal to the well-bred type formerly possessed. One of the clovers found on my Sebastopol place has the color intensified to a bright, rich crimson, which has been reproduced exactly from seed. This is probably a species introduced from South America. A very marked tendency to variation is shown by a large number of clovers when brought to California from distant regions.


Doubtless the most important of the clover importations of recent years is the plant that has become familiar as the alfalfa. This is a form of clover, of which there are several species and almost innumerable varieties, that is adaptable to relatively arid regions, inasmuch as it sends its roots to a depth of sometimes ten or even fifteen feet in search of moisture and nutriment. Such a plant, once it has attained a fair growth, is almost independent of the rainfall for months together. Moreover, the vigor of root of the alfalfa is duplicated by the complementary growth of its foliage, which develops so rapidly and so persistently that it may be cut three, four, and even five times in the season, depending upon climate. The enormous productivity of alfalfa, together with its adaptability to arid regions, led to glowing predictions as to the importance of this new forage crop, when it was first introduced a few years ago. In the southwestern part of the country the predictions have been more than justified, but alfalfa has failed to make its way in the Eastern and Northern States as- rapidly as had been expected. The probable reason for this is that our most common alfalfa was brought from Peru or Bolivia. Had the plant come from Patagonia or Southern Chile instead, or from Russia, its original home, being therefore represented by hardier varieties, it would probably have spread all over the Eastern States and have added vastly to the value of the forage crop everywhere. But now hardier types of alfalfa are making their way to the North, and even into Canada, and possibly selective breeding may develop races more resistant to frost than any that have hitherto been imported. A form known as Turkestan alfalfa has lately been introduced that is recommended for its hardiness. When grown side by side with the ordinary alfalfa on my place, it is difficult to distinguish the two plants. But the Turkestan variety may of course have qualities of hardiness that are not revealed in its appearance. There are other strains being grown that are said to be even more hardy. The alfalfa has so recently been introduced that it has not been extensively experimented upon. There is no plant, however, which can be taken up for development to better advantage by the Government than this thrifty and drought-resisting clover. With this plant, as with the cereals, work should be carried out on an extensive scale by the Government, or by some one who has opportunity to test the plants in a broad and comprehensive way. As already noted, it is useless to develop a small quantity of seed of a new variety, as the practical stock raiser will not be interested in the seed until it can be offered by the ton.


I have received a large number of alfalfas and clovers from the mountains and plains of Chile, and have been struck with the close similarity between some of these and the clovers that have invaded my gardens. Others, however, are individual in appearance and differ markedly from any that I have seen elsewhere. Among the Chilean clovers that I am testing is one that is a giant in its proportions as to leaves, foliage, growth, and blossoms. Another of the Chilean clovers has a heart-shaped brown spot on the leaf. The bloom and seed of this variety closely resemble the common burr clover, but the leaves are several times as large as those of that plant. The burr clover is of peculiar interest because it produces enormous quantities of seed that fall from the stalks when ripe, and in our dry climate may remain edible for some months. The plant was at first thought to be a nuisance, but its value in a region where there is no rain for months together soon came to be recognized. To any one who is not acquainted with the burr clover it is matter for astonishment to see a herd of sheep, cattle, or horses, or a drove of hogs pastured in a field where there is not a vestige of green herbage; and yet to note that these animals are well-conditioned and even fat. They feed on the burr clover seed, the pods of which sometimes cover the ground half an inch or more in depth. The plant itself has withered or disappeared, but the seed-bearing pods furnish a forage crop that has no substitute in this region, although it would probably be of no special value in the East. The burr clover has a small leaf and small blossoms. It runs and spreads by long, wiry, slender stalks, and does not stand upright, so that it could never be profitably cut for hay, making only a tangle of tough thread-like stalks. Yet its peculiar property of producing an abundant crop of pods makes it in some localities quite as valuable a pasture plant as the common red clover is in the East. Neither the crimson clover nor the common red clover is extensively grown on the Pacific Coast. White clover is cultivated for lawns, mostly in combination with blue grass. It will often cover a bare spot under a tree where the blue grass does not thrive. The Alsika clover is another form that is seldom seen in California, partly perhaps because it does not tend to send its roots deeply into the soil, and hence is not as well adapted to a dry climate as are the alfalfas. On the other hand it thrives on a clay soil, and in regions to which it is adapted it is a valuable product. There are numerous other species of clover that have as yet been almost neglected by the plant developer, which offer inviting opportunities. Even without hybridization, plants grown from a given lot of seed will vary greatly. Selection among the most familiar races of clovers would readily result in the development of new varieties that might be of enormous value. The fact that the plant thrives more or less under disadvantageous surroundings has partly accounted, no doubt, for its neglect by the plant developer. But now that year by year there is a growing recognition of the need of intensive cultivation of farm crops, the clovers are sure to come in for a larger share of attention. The leguminous plants, including the peas and beans as well as the clovers, have long been known to be characterized by the unusual amount of their protein or nitrogenous content.


This has led the plant physiologist to regard the clovers as having an exceptionally high food value. As compared with timothy grass, for example, clover contains, pound for pound, a very much larger amount of nitrogen. As nitrogenous foods are the muscle-builders, the value of this is obvious. There has been a tendency in recent years, to be sure, to question whether the nitrogen content has quite the significance that was formerly ascribed to it. It has been pointed out that horses do not need a very large amount of protein foods unless they are exercising actively, and that in this event they usually secure an adequate amount of protein in the grains, chiefly oats, that are fed them. Cattle that are being fattened may thrive as well on foods that are less rich in protein. Milch cattle, and growing cattle, on the other hand, need a nitrogenous diet. And, indeed, all along the line, it is not to be denied that a protein food has exceptional nutritive value. It is partly at least with this in mind that the intelligent agriculturist mixes clover with the timothy in his pastures and in his hay-field. At least a partial explanation of the high nitrogen content of the leguminous plants has been furnished by the discovery that these plants have the very unusual capacity to extract nitrogen from the air. Most plants, as we have seen, are quite powerless to take even the most infinitesimal quantity of nitrogen from the air, and would starve to death for lack of nitrogen even while their tissues are perpetually bathed in it-as the tissues of all aerial plants necessarily are-inasmuch as the atmosphere contains nitrogen as its most abundant element. But the leguminous plants are able to extract nitrogen from the air directly; not, however, with the aid of their leaves or stems, but only by way of the roots, and there only with the aid of the little tubercles that develop under the influence of micro-organisms. It is, indeed, the micro-organism that extracts and fixes nitrogen and makes it assimilable for the plant. The tissues of the plant itself have no direct share in the work, beyond giving hospitable refuge to the micro-organisms themselves. The little tubercles that form on the clovers and the allied plants vary in size and shape with the species of plant, although the micro-organisms that produce the tubercles and that assist the plant in securing a supply of nitrogen are closely related. There are, however, different groups of micro-organisms that are able to produce the tubercles and help in nitrogen-fixation. As micro-organisms are not always present in any given soil, it has been found sometimes desirable to inoculate the soil in which various clovers are to be grown. This may be done by scattering over the field soil from a field in which tubercle-bearing plants of the same species have been grown in the previous year. It has been clearly demonstrated that such inoculation of the soil may lead to much freer growth of tubercles than would otherwise take place, and to the increased vigor and growth of the clover crop. The use of artificial cultures of nitrifying bacilli has also been recommended. It is necessary, however, to treat the solution in a particular way in order to insure that the micro-organisms may maintain vitality. If they are dried slowly under the usual atmospheric conditions, the microbes die. It has been found possible to preserve them by rapid drying of pieces of cotton dipped in a solution containing the microbes. The Department of Agriculture at Washington has experimented with a method of distributing liquid cultures in glass tubes. Special packages of minerals, including phosphate of potassium, sulphate of magnesium, and ammonium phosphate, are sent with the culture tube to make a nutrient medium in which the culture may be developed. The clover seeds are moistened with this liquid culture, dried rapidly, and sown as quickly as practicable. Another method is to sprinkle the liquid on a portion of soil and scatter this over the land. This inoculation of the soil with the nitrogen-fixing microbes constitutes a new departure in agriculture that would have been quite incomprehensible to any one before the day of the modern bacteriologist. But so much has been learned in recent years about the bacteria and their almost universal prevalence and share in the vital activities of animals and plants that the sprinkling of the soil with bacteria seems almost as commonplace a performance as the sowing of seed. This method, however, is obviously only an accessory to the methods of the plant developer. It has exceptional interest as illustrating the application of science to the art of agriculture, but it has no direct association with the work of the experimenter who develops plants by hybridizing and selection. Just how the leguminous plants came to develop this anomalous habit of serving as hosts for the particular types of bacteria that can aid them by the extraction of nitrogen from the air, it is difficult to understand. But the fact that they have developed the habit is of very great importance, because it enables these plants to enrich the nitrogen content of the soil in which they grow, instead of impoverishing it as do other plants. By turning the clover under with a plow, the farmer is enabled to restore to the soil an equivalent of the nitrogen that was taken from it in a preceding season by other crops. The importance of this will be obvious to anyone who is aware that nitrogen is an absolute essential as a constituent of a soil on which good crops of any cultivated plant are to be grown, and who further understands that the available supply of nitrogenous salts with which a depleted soil may be restored has until recently been very limited. Some readers may recall the prediction made not many years ago by the English chemist, Sir William Crookes, to the effect that the world would presently suffer from a nitrogen famine that would greatly reduce the wheat crop, and perhaps subject the entire race to danger of starvation. At that time the chief supply of nitrates came from the nitrate beds of Chile; and it had been estimated that in less than twenty years these beds would be exhausted. No one then could say just how the need of the agriculturist would subsequently be met. But the discovery that leguminous plants extract nitrogen from the air gave partial answer. And almost simultaneoulsy a more complete answer was supplied by scientific workers, headed by the Swedish chemist, Professor Christian Birkeland, in association with a practical engineer, Mr. S. Eyde, who discovered that it is possible to convert atmospheric nitrogen into nitric acid with the aid of electricity. Another method of fixing atmospheric nitrogen was soon afterward developed in Italy. Thus the inexhaustible sources of the atmosphere were made available. So there is no longer any danger of a nitrogen famine, and the developer of plants no less than the consumer of plant-products may look forward without apprehension, so far as the danger of the starvation of plants for lack of nitrogen is concerned. But the mechanical processes of nitrogen fixation are necessarily expensive, and the aid of the clovers and their allies will no doubt continue to be sought for a long time to come by the agriculturist who wishes to restore nitrogen to his fields in the most economical manner. The first crop of clover is usually cut for hay, and a second crop used to turn under in the fall to fertilize the soil. Thus this plant occupies a unique place among farm products. It not only supplies a valuable forage food, but it also helps the farmer to keep his land in a condition of perennial fertility.

-There is nitrogen, worth millions of dollars, in the air over every farm in America-and by the simple process of raising inoculated legumes, we can extract and employ it - not only without expense, but at the same time producing crops of unusual profit.

This text is from: Luther Burbank: his methods and discoveries and their practical application. Volume 8 Chapter 3