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THE IKRIGATION AGE. 



ARID AGRICULTURE 



BY 

 B. C. BUFFUM, M. S. 



Manager of the Wyoming Plant and Seed Breeding Company, 

 Worland. Former Professor of Agriculture in the -Uni- 

 versity of Wyoming and the Colorado Agricultural 

 College, and Director of the Wyoming 

 Agricultural Experiment 

 Station. 



PROF B. C. BUFFUM. 



For crops that must be worked 

 with horses and machinery, it is 

 not practical, as a rule, to make 

 the banks over one and one-half 

 to two and one-half feet high, as 

 there is liable to be damage to farm 

 machinery in crossing higher 

 banks. If the side slopes of the 

 banks are made slight, too much 

 area is taken from the land that 

 could otherwise be cropped. This 

 system entails a large first cost 

 and is also subject to the following 

 disadvantages: The top soil, 

 usually the best, is removed to 

 form the banks; even after level- 

 ling, the checks usually have 



enough slope so that the water stands considerably deeper 

 on the lower end of check than on the upper, which pro- 

 duces unevenness in the crop, some getting too much and 

 some too little water. Considerable area is withdrawn from 

 cultivation by the levees; it is hard to cross levees with 

 heavy machinery. The great advantage is in the ease of 

 irrigating and the large head of water that may be 

 quickly applied and thoroughly controlled by the irri- 

 gator. 



The "contour-check" method differs from the rect- 

 angular only in the way the levees are made. In this sys- 

 tem surveys are made of level, or "contour" lines, spaced 

 as far apart as it is practical to control the water when 

 irrigating. This system may be used on steeper slopes 

 than the preceding, in which case the checks are long 

 and narrow and usually somewhat curved in outline, 

 following the natural slope. 



Natural Sub-irrigation. 



This is a method that applies only where certain 

 rather unusual conditions exist. These are: First, an 

 impervious hardpan or rock stratum a short distance be- 

 low the surface and parallel with it. Second, a shallow 

 bed of gravel or coarse sand above this, through which 

 water can seep easily from a ditch at the upper end 

 of the field. Third, a rather fine soil not so deep, but 

 that the water from the saturated gravel bed below 

 may be drawn up to within a few inches of the surface, 

 and not so shallow as to be unsuited to cultivation or to 

 be kept too moist from the supply below. So many 

 requirements have to be met that the natural conditions 

 for the use of this method are rarely found, and the 

 system is uncommon. But where the conditions are 

 right perhaps no other practice is so advantageous and 

 cheap. The ground does not have to be so accurately 

 graded as in other methods -the irrigation ditches needed 

 are only the main laterals, made deep enough to let the 

 water they contain into the porous bed below and little 

 labor for irrigation is required. A further advantage is 

 that level, clean culture may be practiced. Nearly all the 

 advantages of the most expensive pipe sub-irrigation 

 system are obtained, and almost without expense. Soils 

 in which sub-soil is filled with free water are not suit- 

 able for deep rooted plants like alfalfa. 



Sub-Irrigation by Pipes. 



This is the most expensive and at the same time the 

 most economical of water of all the irrigation methods. 

 It is best, when putting in a system of this kind for 

 orchards or other very valuable crops, to get the services 

 "f a competent irrigation engineer. The details of this 



method are usually complicated and must be worked out 

 for each farm. 



The Basin Method. 



This is a flooding system used almost exclusively for 

 orchards. It is practiced more in California, perhaps, 

 than in any other state, though it has superseded to a 

 large extent the "check" method, which it very closely 

 resembles. The principal difference between this and 

 the check method of irrigation lies in the size of the 

 checks, the basin containing only enough ground for 

 one tree, while the check method used in orchards may 

 contain ground on which several or even a great many 

 trees are growing. The banks thrown up to retain the 

 water in the basins are usually somewhat better con- 

 structed and more permanent than those in the "check" 

 system. They are also usually much lower; as a less 

 area is irrigated in a check. In some instances they are 

 made so low that a cultivator may be run across them, 

 by little lifting, without much damage to either the 

 machine or the bank. It is commonly thought that, 

 especially where the weather gets very hot, it is in- 

 jurious to allow water to stand around the base of the 

 trunks of fruit trees. Most farmers concur in the opin- 

 ion that the heating of water in the basins by the sun 

 will tend to scald the bark of the trees and that it may 

 even produce wilting on hot days. To obviate this con- 

 dition, usually a small mound is thrown up surrounding 

 the trunk of the tree to prevent the water coming in 

 contact with it. When this is done the water is applied 

 where it is most needed, that is, not just at the base of 

 the tree, but some little distance out and surrounding the 

 tree. Under this area are the small roots that absorb 

 water and feed the tree. Unless cultivation is practiced 

 in the basins, where the ground contains much clay, it 

 is apt to bake badly, and crack. These cracks may even 

 extend through the banks and the basin may need some 

 attention to keep it from leaking. The main objection to 

 this method lies in the very large first cost of preparing 

 the land. The actual labor of irrigating is very small, 

 although it is necessary to let out the water from one 

 basin when it has stood long enough and turn it into 

 the next one, until all are irrigated. 



Methods for Clay Soils. 



The furrow method, or one of the sub-irrigation 

 methods, is best suited to all heavy soils which are not 

 so dense they will not absorb water readily, as there is 

 more crusting of the surface and cracking when they are 

 flooded. With the furrow methods it is also easy to 

 mulch either the whole surface, or that part lying be- 

 tween the furrows. Seepage or percolation through the 

 soil in the furrow method is aided by leaving the sur- 

 face of the furrow rough, with clods in it, so that the 

 water flows down slowly and has plenty of time to 

 soak to the roots of the plants. 



Methods for Sandy Soils. 



On sandy soils, and especially on soils that are 

 spotted with sandy or gravelly places, the flooding 

 methods are usually more satisfactory than the furrow 

 method. It is sometimes impossible to run a small 

 stream of water in furrows through a loose sandy or 

 gravelly soil, as it sinks into the soil almost as fast as 

 it can be turned into the furrow. For short distances 

 this may be satisfactory, but in general it is best on such 

 soils to use a large head of water and flood the ground 

 as rapidly as possible. The check method of flooding 

 makes this kind of ground especially easy to work. 



Methods for Steep Slopes. 



The contour check method may be used on steep 

 slopes. When the checks are made very narrow on this 

 kind of ground, this method is called terracing. Furrows 

 may be also used on moderately steep slopes, where they 

 are run on grades only slightly below contour lines. 

 Care must be taken with any method on steep ground, 

 that the water does not get a start down the steepest 

 slope, as it very quickly gathers force and volume and 

 may cut the ground badly. 



Methods for Slight Slopes. 



For very level ground the check method is often 

 found most advantageous. For slight slopes the furrow 



