Preparing land for irrigation and methods of applying water . PENING 6X8 ing years. In ordinary prac-tice the ditches forclover and alfalfaare located 100 feetapart, and the damsare made of manureinstead of time before afield is to be irrigatedand after the ditch-ing is done, manure,containing consider-able straw, is depos-ited in small heapsabout 60 feet apartalong each ditch. Aday or two* beforethe water is turnedon each heap is ar-ranged in a morecompact form andreceives a coveringof earth from 1 to 2inches thick on itsupper face. This manure and earth dam retains the water in th
Preparing land for irrigation and methods of applying water . PENING 6X8 ing years. In ordinary prac-tice the ditches forclover and alfalfaare located 100 feetapart, and the damsare made of manureinstead of time before afield is to be irrigatedand after the ditch-ing is done, manure,containing consider-able straw, is depos-ited in small heapsabout 60 feet apartalong each ditch. Aday or two* beforethe water is turnedon each heap is ar-ranged in a morecompact form andreceives a coveringof earth from 1 to 2inches thick on itsupper face. This manure and earth dam retains the water in the ditchsufficiently long to water the small intervening space. It is thenbroken and the water passes on to the next dam. After the first irrigation the coarse manure and straw are depositedon the edge of the ditch and may be used a second or even a thirdtime. Manure dams similar to these just described are frequently used forthe second irrigation of grain crops. It should be stated, however,that this practice is less generally used now than in former Fig. 2b.—Canvas dam with opening to divide an irrigating stream. 65 Steel dams are now quite commonly used instead of earth dams ingrain fields, and the ordinary canvas dam is being substituted formanure dams wherever clover and alfalfa are extensively grown. In some sections of Gallatin Valley, particularly under the WestGallatin Irrigation Companys canal,the field ditches are parallel and ex-tend down the steepest slope fromthe supply ditch at the top of thefield to the catch ditch at the bot-tom. In this method both earth andmanure dams are used in a mannersimilar to those of grade ditches,but the distribution of the water isdifferent. This may be seen by aglance at figure 30. Water flows outof the ditch from both sides and,the grade being steep, it is dis-tributed from openings made justabove each dam. The common practice of irrigat-ing from steep, parallel field ditchesin Beaverhead County. Mont., isthus described by
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