THE IRKIGATION AGE. 



265 



First. The great problems pertaining to the storing 

 of the mountain waters in large reservoirs, to be led to 

 the farms during the growing season when the plants 

 most require moisture. These problems are almost 

 wholly of an engineering nature, though some of them 

 concern themselves directly with the questions regarding 

 the maintenance of the forest and range growth upon 

 the mountains. 



Second. Following the building of reservoirs, is the 

 construction of the canals through which water may be 

 carried to the farms. Here again numerous problems 

 are involved, but these are also almost exclusively of an 

 engineering nature. 



Third. The farmer who receives water from the 

 canal to be applied upon his farm also finds himself 

 confronted by numerous problems of the most vital 

 nature, so far as the profitableness of his operations is 

 concerned. These problems are, in complexity and dif- 

 ficulty of solution, no whit behind those of the first two 

 classes. 



The problems of the first two divisions are much 

 better understood than those of the third. This is due 

 largely to the fact that dams, reservoirs and canals have 

 been built in all countries and in all ages for purposes 

 other than those involved in the art of irrigation. 



SOME SOIL PROBLEMS OF IRRIGATION. 



It is to the problems that confront the farmer in the 

 actual application of water on the farm that the in- 

 vestigations undertaken by the Utah Experiment Station 

 in 1900 have concerned themselves. In the experiments 

 it has been clearly kept in mind that, in an arid region, 

 the land itself has little value unless accompanied by a 

 water right; and, moreover, that the amount of availa- 

 ble water, even when all possible reservoirs shall have 

 been built, will be sufficient to cover only a small frac- 

 tion of the arable land. Water has been studied, there- 

 fore, in its relations to both soils and crops. 



The water applied to different soils sandy, loamy, 

 clayey and calcareous has been followed in its down- 

 ward movement and it has been shown that by proper 

 precautions clrainage may be avoided and the danger of 

 forming alkali in the lowering lands diminished or al- 

 together eliminated. The lateral movement of water has 

 likewise been investigated to determine to what extent 

 the water applied to a field disappears by the lateral flow 

 of soil moisture. The upward movement of soil water, 

 after an irrigation, has been traced, with reference to the 

 nature of soils found in the arid regions, the total 

 moisture in the soil and the kind of crop growing on 

 the soil. It has been found that the rate of loss of 

 water from bare soils depends upon the nature of the 

 soil, the depth of the soil, the hardpan or gravel bottom, 

 the per cent of moisture in the soil, the meteorological 

 factors, including temperature, sunshine and showers, 

 the time after irrigation, the condition of the top soil, 

 and the method of irrigation. The rate of loss 

 from soils on which crops are growing has been found 

 to depend upon the same factors, and in addition, upon 

 the kind of crop grown and the age of the crop. In 

 studying all of these conditions it has been found that 

 there is a method of treatment which is better than all 

 others in the conservation of soil moisture. 



The relations of soil fertility to irrigation has also 

 been studied with reference to the composition of the 

 irrigation water, the nature of the soil, the addition of 

 various natural and commercial fertilizers and artificial 

 drainage. The results of this branch of the work have 



also been very interesting in showing that there is a 

 mutual dependence between soil fertility and use of 

 water by plants. In connection with the question of soil 

 fertility, the reclamation of alkali lands by means of 

 under-drainage has here been investigated briefly, with 

 the result that it seems probable that alkali lands may 

 be reclaimed by under-drainage, and that, by proper 

 methods of irrigation, they need not again be subjected 

 to alkali conditions. 



The conservation of the moisture, already in the soil, 

 has been studied with reference to the stirring of the 

 top soil, the addition or removal of soluble salts, the 

 quantity of water to be added at each irrigation, sub- 

 irrigation, standing water near the surface, and the 

 crops. The consideration of these problems has led to 

 conclusions which, if applied by the farmer, may lead 

 to the saving of one-third to one-half of the water now 

 ordinarily used for the production of the common field 

 crops. 



The various methods of irrigation, flooding, fur- 

 rowing and sub-irrigation, have been tested with results 

 that indicate plainly the relative merits of these methods 

 of supplying water to soils. 



THE CROP PROBLEMS OF IRRIGATION. 



The relation of water to crops has also been investi- 

 gated systematically and exhaustively. The total yield 

 of crops has been found to depend not only upon the 

 total amount of water, but also upon the time of appli- 

 cation, the frequency of application and the manner of 

 application. The results of this investigation, which 

 will be published in a later article, have been of a more 

 surprising nature, and show the way to an economical 

 use of water in the arid regions. However, there is 

 much to be considered by the farmer besides the actual 

 yield of crops obtained. For instance, with certain crops 

 it may be very desirable to be able to hasten the ma- 

 turity and the question of being able to delay or hasten 

 the ripening of crops has been studied with most im- 

 portant results. 



In another investigation, the relative proportion of 

 the different plant parts leaves, stalks and roots as af- 

 fected by irrigation has been determined, and it has been 

 found possible to produce plants at will with a larger or 

 smaller proportion of any one of these parts than is 

 ordinarily found. 



Of prime importance, also, have been the results ob- 

 tained in the study of the quality of various crops as in- 

 fluenced by irrigation. It has been discovered that the 

 various constituents of plant parts, such as gluten in 

 wheat, starch in potatoes and sugar in beets, may be in- 

 creased or diminished at will by suitable methods of 

 irrigation. Incidentally, the milling quality of grains 

 grown with different amounts of water, and the cooking 

 quality of potatoes, cabbage, carrots and other vegeta- 

 bles as depending upon irrigation, have been deter- 

 mined. 



Of even greater interest than the questions already 

 mentioned are the attempts to breed certain characteris- 

 tics into plants by controlling irrigation. For instance, 

 the best flour for human food is that which contains a 

 high per cent of gluten, and by irrigation it is possible 

 to increase or diminish this per cent. The attempt has 

 been made to produce grain so rich in gluten that when 

 grown in countries of abundant rainfall where irrigation 

 is not practiced it will yield seed that is also rich in 

 gluten. Can this be done in the case of wheat and other 

 crops, and it seems very probable that it can be, it will 



