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IRRIGATION PRACTICE 



tion of the light soils characteristic of arid regions. It 

 reduces evaporation; tends to prevent over-irrigation, 

 and, because of the ease with which the furrow may be 

 covered, soon after irrigation, the rise of alkali is delayed. 

 There is little disturbance of the top soil, and baking is 



FIG. 53. Standpipe supplying furrows with water. 



largely eliminated. The system once laid off requires 

 little attention; one man can irrigate a large number of 

 acres in one day. The method is inexpensive. 



The furrow method of irrigation also has some dis- 

 advantages. Large heads of water cannot be used in the 

 small furrows. It may be desirable, especially in the 

 spring, to apply quickly a large quantity of water to a 

 given field. This is practically impossible with the fur- 

 row method of irrigation. It is difficult to admit the 

 same quantity of water to each of the many furrows. 

 Special attention must, therefore, be given to establishing 

 checks in the supply ditch at suitable intervals, to force, 

 as nearly as may be, the same quantity of water into each 

 furrow. Tubes or lath boxes, connecting the furrows with 

 the supply ditch, are helpful in establishing a steady flow 

 in each furrow. (Fig. 56.) The uniform use of water 



