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THE IRRIGATION AGE. 



THE SUPPLEMENTAL VALUE OF IRRIGATION. 



DR. JOHN A. WIDTSOE, 



Director Department of Agriculture, B. Y. University, 

 Provo, Utah. 



THE TWO PHASES OF IRRIGATION DEVELOPMENT. 



There are two distinct phases to the work of re- 

 claiming our desert lands by irrigation. The impound- 

 ing and distribution of the waters by mighty dams and 

 canals form the first; and the proper and economical 

 use of the water on the farms, the second. The former 

 of necessity precedes the latter, but when the labor ex- 

 pended on the vast irrigated areas, and the possible 

 resulting crops, are stated in dollars and cents, it can 

 not be denied that the proper use of the irrigation 

 water is, financially, superior to the money invested in 



crops can not be produced profitably on our western 

 deserts without irrigation. It is only within the last 

 few years that this idea has been shown to rest on un- 

 reliable foundation. Rain and snow fell upon the 

 western deserts. Along tbe edges of the Great Basin, 

 for example, the annual precipitation varies from twelve 

 to eighteen inches, and it seldom falls lower than eight 

 inches at any place in the Basin region. Over a large 

 district surrounding the Navajo Indian Eeservation, 

 including portions of Utah, Colorado, New Mexico and 

 Arizona, that ordinarily are looked upon as being hope- 

 lessly desert, the rainfall during the last twelve months 

 was a little more than eighteen inches the average 

 there is perhaps fourteen inches. Over large portions 

 of Wyoming, Idaho and Montana, the annual average 

 precipitation is even higher. More water is needed in 

 arid than in humid regions to produce one pound of 



Tunnel Showing Sage Brush Country in Nevada. 



the construction of the dams and canals. The accumu- 

 lated effect of errors in the use of water, in one year, 

 may easily equal a large proportion of the total cost 

 of the works under which the lands lie. 



At the present time much is said about the reser- 

 voirs and canals to be built; unfortunately, much .less 

 is said about the relation of water to soils and crops. 

 The extension of our knowledge of the farmer's side 

 of irrigation should go hand in hand with the engi- 

 neer's work. If this be not done much loss will in- 

 evitably follow. 



It is not true that all is known of the proper use 

 of irrigation water that needs be known. The prin- 

 ciples of the practice of irrigation are not well devel- 

 oped ; many are not at all known ; the science of irri- 

 gation is yet to be built. This paper is a contribution 

 to the farmer's side of irrigation. 



THE VALUE OF THE NATURAL PRECIPITATION. 



Especially in the far East, but also among our 

 own western people, the myth has become current that 



dry matter. The amount of water represented by an 

 annual precipitation of eight to eighteen inches, if 

 properly conserved, is sufficient to produce profitable 

 crops of many of the useful plants. To illustrate: 

 If 750 pounds of water are required to produce one 

 pound of dry matter, a little less than four-tenths of 

 an acre inch would be sufficient to produce one bushel 

 of wheat per acre. With a precipitation of twelve 

 inches a little more than thirty bushels of wheat per 

 acre should be produced, if all the water that falls 

 soaks into the soil. Naturally, this is far from being 

 true, and the crop producing power of the natural pre- 

 cipitation is correspondingly decreased. Yet, by proper 

 methods of soil treatment one-half to three-fourths of 

 the precipitation should easily be stored in soil and 

 be kept there until required by plants. Demonstrations 

 in Utah and Colorado have shown that it is possible, 

 with proper methods of cultivation to produce as high 

 as thirty-five bushels of wheat every other year with 

 an annual rainfall of about fourteen inches. 



Keeping in mind this rather high crop-producing 



