46 



so tliiit the furrows may carry the water witliout flooding; tlie expense 

 of furrowiiii; out before each irrigation and of cultivating afterwards, 

 and the necessity of jihinting far enough apart for horse cultivation; 

 the difficulty of applying water evenly in very sandy soil, and the loss 

 of water by seepage in head ditches, especially where the flow used is 

 small. 



In irrigating with a liose ])y hand many use no nozzle at all, simply 

 putting the tlunnb over the end of the hose to make a fine spray. A 

 cheap nozzle is often made by flattening the end of a piece of ordinary 

 pipe. Others use a fine-hole sprinkler or some forui of ]iatent adjust- 

 able nozzle. 



"\Miere s]:)rinklers are used, the simple forms shown in figures 5 and 6 

 are nnich in favor. One widely used type of water witch (fig. 6) con- 

 sists of a small revolving device with two concave 

 horns which revolve, owing to the reaction of the 

 water flowing Ijetw^een them. These sprinklers 

 operate with a pressure of 1 5 to .30 pounds, and 

 w411 cover a circle 15 to 30 feet in diameter. 

 Their simplicity and cheapness have led to their 

 wide adoption. The W'ater passages through the 

 sjirinkler are fairly large and not easily clogged. 

 Many irrigators use small brass plugs with one 

 small hole drilled in the center. Revolving-arm 

 sj)rinklers are very little used, being expensive 

 and too easily clogged. 



The various arrangements of multiple sprinklers 

 are described above in connection with the de- 

 tailed data regarding truck-irrigation plants, and 

 a few details are shown in figure 7. 

 Where pipe is laid on the surface, it is frequently taken up and 

 stored away during the w inter, making a gre^t deal of labor. It is 

 usually better to bury the pipes below^ the depth of cidtivation, pro- 

 vision being made to drain the water out, so as to prevent freezmg. In 

 many cases there is a tendency to buy" too small pipe for mains, wdiicli 

 needlessly increases the pumping head, and thus the fuel cost. 



THE COST OF IRRIGATION. 



The cost of irrigation includes, besides the cost of applying water 

 already discussed, both interest and repairs on the plant and fuel and 

 attendance for pumping. AVhere city water is used the fuel and 

 attendance are included in the rate paid for water. Interest and 

 taxes may be taken at 7 per cent of the cost of the plant, and deprecia- 

 tion, repairs, and renew^als at 13 per cent, or 20 per cent annually as 

 the total fixed charges on small pumping plants. This expense is 

 constant whether the plant is used or not. 



Fig. i). — Simple nuzzle. 



