346 IRRIGATION PRACTICE 



United States it varies from 60 to 300 acres; where water 

 is most abundant it varies from 60 to 120 acres; where 

 water is less plentiful it varies from 100 to 150 acres, 

 occasionally rising to 200 acres; where water is very scarce, 

 as in southern California, it rises to 300 acres. There are 

 records to show that the duty of water has reached even 

 1,000 acres to the second-foot of water, but such figures 

 are as yet exceptional and need not be given serious con- 

 sideration as part of present-day practical irrigation 

 agriculture. 



Elwood Mead, one of the world's chief irrigation 

 authorities, declares that the duty of water in the United 

 States is on the average quite as high as in the older 

 countries, but predicts that the duty will be doubled as 

 more perfected methods of agriculture are adopted. 



F. H. Newell, the illustrious director of the Recla- 

 mation Service of the United States, believes that for good 

 farming an average of 12 acre-inches for each acre, during 

 the irrigation season, should be enough, except for alfalfa 

 and certain similar crops. This, for a four month's irri- 

 gation, is a duty of 206 acres. Newell further states that 

 the duty of water often reaches 250 to 500 acres to the 

 second-foot of water. 



209. The Utah results. The careful studies of the 

 Utah Station on the water requirements of crops indicate 

 that, when the natural precipitation is properly conserved, 

 even 6 acre-inches an acre will produce fairly good yields 

 of all the ordinary crops. If more water be applied the 

 yield is smaller in proportion. The Utah results would 

 lead to the belief that where the annual rainfall is from 

 12 to 15 inches a depth of water from 10 to 20 inches is 

 best for ordinary farm crops, and that the best quantity 

 lies nearer the smaller figure. A depth of 12 inches prob- 



