59 



duty out of tho water supply, for the reason that two .)r three crops 

 may l)e o-rowu on the same tieUl in one season. A farmer who is 

 entitled to the continuous use of 1 cubic foot per second for 80 acres 

 may thus ])e al>h» to supply water to three crops of alfalfa at the same 

 cost as to one ci'op of wheat. In doin^' this he may use more than 

 three times the amount of water, l)ut, assuming thiit he pa3's season 

 rates, the cost would not differ. 



It is only, however, on the diversified farm that a continuous stream 

 can be utilized to the fullest extent. When a dozen diti'erent crops 

 are grown on an 80-acre farm the proper time to irrioate is seldom the 

 same for any two, and so it is possil)le to keep a small stream flowing 

 continuously on first one and then another of the subdivisions. 



On account of the large size of the average farm and the plentiful 

 supply of water, the necessity for time rotation in the d(divery of 

 water has not been keenly felt in Montana up to the present. It is 

 only when a scarcity exists that neigh])ors arrange to use in turn the 

 supply which belongs to, say, three projjrietors. In this way each of 

 three farms can secure an effective irrigation head for one out of 

 every three days. As water l)econu\s scarce and of higher value and 

 as the farms ])ecome ivduced in size this method of delivering water 

 will graduall}' become more common. 



The subsoils of western lands when first l)rought under irrigation 

 contain little moisture. The most striking characteristics of these 

 formations are their great depths and the close similarit}^ which exists 

 between the surface and subsurface layers. Apart from their darker 

 color, due to decayed vegetable matter, there is little to distinguish 

 top soils from bottom soils, and the roots of })lants extend to great 

 depth through tfie latter. On account of these prevailing- physical 

 features a large part of the water which is applied for the first few 

 seasons is absorbed. Cases are common in which new land has absor))ed 

 in one season a quantity of water which would have covered the surface 

 to a depth of feet. To claim that this large volume correctly repre- 

 sents the dut}' for such land is a misrepresentation, l)ecause the open 

 space in the subsoil is gradually filled with water and the ground-water 

 level in time rises nearer the surface. It is a fact, however, that new 

 land requires much more water per acre than old cultivated fields, and 

 crops are likely to sufl'er if it is not supplied. 



Other conditions being similar, less water will be used on a farm 

 which has a good system of ditches and laterals and a well-cultivated 

 even surface. The beginner is not always posted as to the best way 

 to lay out and Imild farm ditches, and he may not possess sufficient 

 means to properly prepare his fields for irrigation. These defects 

 invariably prove quite costh^ in the end, when measured in waste of 

 water and small yields. In an arid country thorough cultivation serves 

 a double purpose in that it increases the yield and prevents the escape 



