Use and Wastk of \Vati:r 215 



night compared with the day time. It is a great mistake to shut 

 down pumping plants each evening. 



7. I'^limination of weeds. The waste of water to raise weeds 

 should be inchided with evaporation losses. Weed farming is 

 unprofitable. 



8. Windbreaks. They should be planted along the ditch banks 

 and the road sides. Every farmer should raise his own fence posts 

 and fire wood. W^ind movement in the Salt River Valley is greatly 

 reduced by the long rows of magnificent cottonwoods with which 

 the landscape is checkered. The nearby fringes of fields require 

 additional fertilization, but the net result of the windbreaks is 

 beneficial. 



SEEPAGE LOSS FROM IRRIGATED FIELDS 



As a rule, this loss is even greater than the preceding one. It 

 is particularly severe on light soils. It could be avoided to a large 

 extent if no moie water were ai)plied at each irrigation than the 

 amount that can be held by the soil within reach of the plant roots. 



An ideal irrigation consists in ap])lying the right amount of 

 water, evenly distributed over the field. Thruout the central and 

 southern portion of Arizona the practice for field crops is to lay out 

 the field in long strips or "lands." In many observed cases the 

 water, turned in at one end, requires from one to three hours to 

 traverse a land to its lower end. As soon as the water reaches the 

 lower end the ditch water is turned to another land. For one or 

 two hours, then, the head end of a land gets water, part of which 

 soaks downward beyond the reach of, and beyond the needs of, the 

 plant roots, while at the far end the land receives water for fifteen 

 to forty minutes. Surely, this is not an ideal irrigation. In 1913 

 the author made several tests of the evenness of distribution of the 

 water. In one case, on heavy loam, it w^as found that the per- 

 centage of soil moisture at the head of a land, for six feet depth, 

 was increased from 24.1 to 26.3 percent by a 4-inch average irriga- 

 tion, w^hile at the tail end the soil moisture w^as increased from 15.4 

 to 18.2 percent. In another case on sandy loam the soil moisture 

 at the head end was increased from 14.3 to 21.1 percent and at the 

 tail end from 8.3 to 12.2 percent. In both cases, therefore, the head 

 end had more soil moisture before irrigating than the tail end had 

 after irrigating — a preposterous condition. Inasmuch as the alfalfa 

 near the foot of each land was making excellent growth it follows 

 that the head ends of the land were getting unnecessarily large, 

 wasteful amounts of water. On one of the fields thus tested the 



