222 BuIv1vE:tin 88 



1. He can note with a watch the number of minutes during 

 which the head end and the center and the tail end of the lands or 

 furrows get water. 



2. Pits dug to a depth of six feet with a pesthole digger at 

 different points in a field will show whether or not the irrigation 

 is uniform, and whether the soil is wet amply or too much. The 

 pits should be dug about 12 hours after the irrigation. In lieu of 

 the pits, a sharp stick can be thrust into the ground at various 

 points and much can be learned thereby of the penetration of the 

 water. The Southwest Cotton Company uses a pointed metal rod 

 with a groove one foot long in the side near the point. By driving 

 the rod to any depth, rotating it there, and then withdrawing it, a 

 sample of the soil at that depth is obtained. A soil augur is a con- 

 venient and useful tool ; every farmer can well afford to own one. 



3. Observation of the water level in nearby wells may indicate 

 whether the groundwater plane is rising due to over-irrigation. 



4. Does the soil surface bake? If so, there must be a heavy 

 loss of water by evaporation. A farmer can easily demonstrate to 

 his own satisfaction how far evaporation losses can be reduced by 

 cultivation. 



Ditch losses are best measured by setting weir boards and meas- 

 uring the quantity of water at two points. 



The efficiency of irrigation can be defined as the ratio of that 

 portion of the water actually utilized by the crop to the total quan- 

 tity applied to the land. It is the farmer's province to endeavor to 

 make this ratio as high as possible, and thus to decrease the amount 

 of water needed for his ranch. 



The courts of Arizona have excellent opportunities in their 

 decisions in cases establishing water rights to limit the diversion 

 and applications of irrigating water to the real needs of crops, plus 

 a reasonable allowance for water losses which it is impractical to 

 prevent. Usually the courts have established the duty of water 

 much lower than it should be. The Kent decree in Maricopa 

 County and the Lockwood decree in Pinal County fix the limit of 

 application at 5.5 acre-feet per acre annually, the water to be 

 measured at the land. The records of the Salt River Valley Water 

 Users Association show that the average amount of water bought 

 and paid for by farmers during the past six years has varied from 

 2.36 acre-feet per acre to 3.67 acre-feet. The decree of 1905, adjudi- 

 cating water rights of Graham County, fixes the duty of water at 

 "one-half miner's inches continuous flow to the acre." This is 

 equivalent to 9 acre-feet per acre annually. Under the license of 



