136 



THE IRRI'GATION AGE. 



THE ECONOMIC USE OF IRRIGATION WATER 



By FRITZ KNORR 



Of the United States Experiment Farm at Scotts Bluff, Neb. 



THE economic use of irrigation water is a prob- 

 lem that should be given more consideration in 

 the future than it has received in the past. It seems 

 that an engineer's problem is far from solved when 

 the irrigation system is completed ; and the organi- 

 zation that finances the proposition does not meet 

 with the real grief until the entire system has been 

 in operation for several years. The cause of much 

 trouble is the call for more water on one side, and 

 the constant cautioning for a more economic use on 

 the other side, and sometimes the positive refusal 

 to supply more water. 



Each side is right when their reason and cause 

 is studied by itself, but let us make it a common 

 cause, a community problem, and the proposition 

 has a different aspect. The farmer's side is : We 

 must have more 

 water to grow 

 larger crops ; a 

 large head of 

 water in order 

 to be able to 

 cover a larger 

 area in less 

 time ; a constant 

 run instead of 

 an intermittent 

 supply, that we 

 may irrigate at 

 any or all times. 

 The water hold- 

 ing organization 

 says : Use less 

 water and your 

 crops will be 

 just as large; a 

 constant run and 

 a large head 

 means waste and 

 that will ulti- 

 mately lead to either seepage or alkali. 



The water user, on the other hand, feels that 

 the water furnisher wishes to protect his interest 

 in order to supply a larger territory with water, 

 which belief is often justified to a certain extent. 

 On the other hand, all land holders should be con- 

 sidered ; those on the low lands that are affected 

 by injudicious practices above should receive con- 

 sideration. 



All seepage cannot be prevented ; the contour 

 of the land, soil formation, and even some of the 

 soils are conducive to seepage, but vast areas have 

 been made worthless by negligent methods. Many 

 farmers have been accused of shiftless methods in 

 irrigation. It is true that many are shiftless and 

 careless in the application of water, but we believe 

 a far larger portion are not aware of the conditions 

 that they are bringing about by the methods they 

 employ, and it is also due to their lack of knowl- 

 edge of soil conditions and plant requirements, and 

 when once their attention has been called to this 

 they will realize the necessity as well as the ad- 



vantage of a decreased use of water. 



This year, more than ever, have we realized 

 our shortcomings, or lack of knowledge, if you will, 

 in the time and method of the application of irriga- 

 tion water. It would be folly for anyone to lay 

 down a rule stating that irrigations should be so 

 far apart and the water should be allowed to run a 

 certain time in order to. get the best possible re- 

 sults with irrigation. These factors depend entirely 

 upon the slope of the land, nature or texture of the 

 top and subsoil and, last, upon the nature of the 

 crop. 



It is not necessarily true, as many believe, that 

 the greatest economy of water is in the use of a 

 large head forced over the greatest possible area 

 that this watrr will carry. On the Scottsbluff (Neb.) 



Substation this 

 year it was 

 found that one 

 a n d one - half 

 second feet of 

 w a t e r turned 

 out and allowed 

 to run over an 

 area having ten 

 inches fall to 

 o n e hundred 

 feet, covered the 

 soil at a depth 

 of three to four 

 inches near the 

 turnout. This 

 v.us allowed to 

 r u n thirty-five 

 minutes. At an- 

 other point in 

 the same field a 

 similar head was 

 run one hour ; 

 near the tail end 

 of the hour run the water moved across the surface 

 very slowly for thirty-five minutes. In comparing 

 the amount of saturation of the thirty-five minutes' 

 run, that where the water ran fast and stood on 

 the surface, the soil was wetted down only to the 

 sixth foot, whereas at the other point, where the 

 water moved slow, the saturation was down to 

 seven feet. To be more accurate, water running 

 fast, the first six feet of soil contained an average 

 of 13.8 per cent of moisture: running slow, the 

 first six feet held an average of 20.7 per cent of 

 moisture. 



In another field water was run across a good 

 slope, having covered over one hundred and eighty 

 feet in about one and one-half hours' run : at the 

 turnout the soil contained an average of 15.1 per 

 cent moisture in six feet, one hundred and eighty 

 feet from the turnout, the six feet of soil contained 

 12.1 per cent of moisture. 



Tests made of our soil, a sandy loam, having 

 an average weight of eighty-five pounds to the 

 cubic foot, the following data was secured : 



of The Earth. 



