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that through the loyalty of your Chamber of Commerce are waving above us today, renders almost anything possible. It will be the aim of every member of our staff to give to the utmost of his strength and ability to advance the agriculture of the state. When the war clouds clear away and peace once more has been established, I can see a vision of prosperity and development in southern California far greater than we have thus far imagined. Our dry lands must be developed; our worthless hill lands must be made to serve a useful purpose. Our whole state must go forward by leaps and bounds, and this station must and will play its part in the great advance.

IRRIGATION AND CROP CONTROL

JOHN A. WIDTSOE

President of the University of Utah, Salt Lake City

The work that will be directed from this building must concern itself largely with agriculture under a low rainfall. For that reason, particularly, will the results of the activities of the Citrus Experiment Station be of world-wide interest.

More than one-half, or more nearly two-thirds of the earth's surface receives an annual rainfall of less than twenty inches. Only a few of the hundreds of agricultural experiment stations devote themselves to the unraveling of the principles which will make possible the reclamation of the earth's arid places, in which perhaps lies the solution of many of the problems that now vex mankind.

Irrigation and dry farming are the twin arts devoted to the production of useful crops on lands under a low rainfall. Dry farming concerns itself with the growing of crops under the natural rainfall, however light it may be; irrigation implies the artificial application of water to lands for the purpose of producing large and steady crop yields whenever the rainfall is insufficient to meet the full water requirements of crops.

Since there is much more land than can be irrigated with the existing water supply, both dry farming and irrigation are indispensable in the conquest of the arid regions, and it may be said in passing that the practice of both may often be applied profitably in humid regions.

Though the agricultural conquest of the earth's large arid areas would mean tremendously much for the welfare of mankind, yet there are careful and sound thinkers who doubt the wisdom of giving any large attention to the study of arid agriculture and notably of

irrigation. These thinkers hold that a permanent civilization cannot be built under the ditch. For their proof they turn for us the pages of history to show that the great nations that have flourished under irrigation have fallen into decay and are almost forgotten. Our destiny under the irrigation ditch is that of Babylon-to be the hunting ground of the archeologist with his wielders of the pick and shovel.

I have no desire to take issue with those who can see no permanence of settlement under irrigation, however tempted I may be to remind them of the experience of China, India, Persia, and Egypt, and of two thousand years of irrigation in southern Europe. I would rather take sides with them to the extent of saying that conditions inevitably surround irrigation, which must be offset by a careful observance of proper cultural operations, else irrigation farming may become precarious.

The first cost of an irrigation system is usually very high; the annual maintenance, even with the cement-lined ditches of Riverside, is quite expensive; the application of the water to the fields involves another expense, and the depreciation of the whole system must always be considered. All of this is above and beyond the cost of farming in a humid region, for the ordinary cultural operations are the same with or without irrigation.

To offset all this, the irrigation farmer can claim usually a more favorable climatic environment and a peculiarly desirable social organization and understanding, both of high indirect value; and moreover he has a certainty of steady crop yields from year to year, which is seldom known in humid regions. To increase the margin of irrigation safety, however, irrigation communities are always on the lookout for new crops, new markets, or improved methods of culture and operation.

The actual success that has been attained under irrigation is attested by the fact that though the inherent disadvantages of irrigation are so well known, it is only within recent eyars that irrigation practice has been given serious attention by the experiment stations. Scientific irrigation knowledge has not kept pace with the advance in general scientific agriculture. This is chiefly due to the fact that agriculture was first studied in the light of modern science in humid regions, first in Europe and later in America.

The very nature of irrigation also tended to retard the feeling for any need of irrigation studies. Even if the soil is poorly ploughed and the seed badly planted, if water is applied a fairly good crop results. Moreover, irrigation seemed a simple matter-to let water flow over the ground. That was all the age-old practice of irrigation in Italy, Spain, and France had to teach.

It is scarcely twenty-five years ago that the first experiment station study of irrigation was undertaken; about twenty years since the Department of Agriculture began its irrigation studies, and most of our present scientific knowledge of irrigation practice is less than fifteen years old. Though almost the last great agricultural art to be studied, it has shown itself capable of responding in a very unusual degree to refinements of agricultural processes. The opinion may well be hazarded that as more scientific study is given the subject, irrigation will assume a strength that will render it superior in economic results to any other branch of agriculture. This, however, will necessitate a careful study of the underlying laws of irrigation practice.

Whether farming be irrigation or humid, the necessary sunshine, air and soil are under approximately the same small control. Under irrigation, however, the water factor is under very large control; whereas the humid farmer must be content to have it rain upon the just and the unjust alike, without the power to add to or take away from the quantity that descends. This is the great difference between the two kinds of farming. The irrigator may vary the quantity of water applied to the crops; he may apply it at various times and by different methods. When the quantity, time or method of application is varied, the crop is definitely affected. It may be that from this crop control will develop a permanent system of irrigation. It is to this thought that I would direct your attention.

The quantity of water necessary for the production of plants has been given much study. The results from actual irrigation practice have been found very misleading, for in general wherever water is abundant, much is used; wherever scarce, little is used. On some of the remote ranches, near large rivers, the use of ten acre feet is not at all uncommon, whereas in the neighborhood of Riverside, water has a service higher than was thought possible a few years ago. For the ordinary agricultural crops the pounds of water required to produce one pound of dry matter, vary from 150 to 2000 or more, under varying field conditions. The only general law that seems to govern is that the crops with heaviest acre yields use less water for each pound of dry matter than do those with smaller acre yields. Consequently, corn, carrots, sugar beets, barley and alfalfa, all high yielders use less water for a pound of dry crop than do oats, wheat and potatoes. In times of famine this law, should it be found to be correct, might show the way to safety.

When the quantity of water offered a crop is varied, there is a corresponding variation in the yield obtained. In general, the old idea holds, that the more water is applied the larger the yield of the crop, but only within narrow limits. The outstanding fact is, that the

more water is applied, the less the crop return for the additional water used. For example, one investigator found on a deep fertile soil, in a district where the annual precipitation is about thirteen inches, that five inches of irrigation water yielded thirty-eight bushels of wheat to the acre, and that twenty-five inches, or five times as much water, gave a yield of forty-seven bushels, or only nine bushels more. In other words, if the twenty-five inches of water had been spread over five acres of land, 190 bushels of wheat might have been harvested, as against forty-seven bushels, when the same quantity of water was applied to one acre.

In one experiment, one acre of potatoes receiving five acre inches of water gave 154 bushels of potatoes; on another acre, thirty inches of water were applied with a yield of 244 bushels. If these thirty inches of water had been spread over six acres of land, the yield from the water so used would have been 924 bushels, as against 244 bushels from the one acre, but with the same quantity of water.

The variation is the same with all crops, whether in the field or orchard. The more water applied, the smaller the return in crop for each unit of water used. This law, which has been confirmed by several investigators, offers an excellent illustration of the crop control made possible by irrigation. Just how it is to be applied is yet to be determined. Students of farm management must consider all the factors involved, and determine for us the quantity of water which, economically, should be used on one acre, also whether a community should use the water at its disposal on a larger or smaller area than is now irrigated.

I leave you to consider our duty in connection with this law, in this hour of great national concern. Over the irrigated area probably not less than twenty-five acre inches of water are used per acre for the production of the common crops. If that quantity were made to cover two or three acres, the total yield of foodstuff from the irrigated West would be more than doubled.

As stated, the more water is used the smaller becomes the relative crop return. At last there comes a point, at which there is an actual diminution of the yield. A vigorous stand of corn yielded ninetyone bushels of grain with five inches of water. The yield increased slowly until twenty-five inches had been applied, when it began to diminish, and with forty inches of water only ninety bushels of grain were obtained-a little less than with five inches of water. This also is a law generally found to be true. The curse of the early days of irrigation in the West was over-irrigation. None has dared to compute the loss in crops alone, due to the application of water sufficient to hinder the growth of plants. The water-logging of irrigated lands might measurably be overcome, if every irrigation farmer

were content to use reasonable quantities of water. In this matter again, the irrigation farmer has a definite control over his crop.

However, this is not the end of the story. As the application of water is varied, every part of the plant is affected. When little water is used, the proportion of roots is large. As more water is applied, the stems and leaves develop more rapidly. Increasing the water, within definite limits, lengthens out the plant, and in the case of the grains, increases the number of seed-bearing stalks from the seed. Even the shape of the leaves is determined by the quantity of water used. Corn leaves are narrow and pointed when produced with little water, wide and rounded when more water is added. Potato leaves are thick and long-celled with little water, thin and short-celled with much water. The color, stiffness and very shape of the plant may be changed by changing the quantity of irrigation water used throughout the season.

Of more direct interest is the fact that the relative proportion of leaves, stalks and other plant parts may be controlled by irrigation, since seeds and fruit are usually more valuable than leaves, and leaves more valuable than stalks. Forage plants grown with little water are usually leafy but the judicious application of water may increase the proportion of leaves. It seems possible by varying irrigation to produce, for instance, leafy or stalky alfalfa.

In cereal crops, the seeds are of chief importance. It has been repeatedly demonstrated that the proportion of grain in the whole plant becomes smaller as more water is applied. In one set of experiments, wheat grown with five inches of water yielded 46 per cent of grain; when twenty-five inches of water were used, the yield of grain fell to 33 per cent. That is, water may be made to produce wheat or straw at the will of the farmer. The fruits are likewise affected by irrigation. By proper use of water the edible portion of cherries was increased 5 per cent, of plums 10 per cent, of prunes and apples about 2 per cent, and the proportion of small potatoes was in one case reduced from one-fourth to one-tenth of the whole crop. Such results are far reaching once they become part of our agricultural practice.

It is clear that the development of the crop in all of its parts may be controlled by the irrigation farmer, who may apply at will much or little water to the land. In these later days, however, we are not placing all emphasis on the quantity of the crop harvested. The quality is rapidly becoming a first consideration. Wheat, sugar beets, potatoes, tomatoes, fruits and many other crops must already meet quality tests in order to command the best prices. An increasing popular understanding of the laws of nutrition will more and more establish food demands based upon quality.

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