412 



IRRIGATION PRACTICE 



lation of the irrigation plant and leave a margin besides. 

 Irrigation in humid climates probably always pays, unless 

 exceptional difficulties are encountered in securing and 

 distributing water. One drought, unprovided against, 

 frequently causes a loss that would pay for the irrigation 

 system and much else. 



244. Methods of applying water. The methods of 

 applying water in humid regions are those in general use 



Reservoir 



Public Road 



FIG. 120. An irrigation plant in Pennsylvania 



everywhere. Furrowing is probably best, except where 

 the soil is very clayey, or where meadows are flooded with 

 water. In humid regions, on many relatively small tracts 

 devoted to irrigation, specialized crops are usually grown, 

 yielding high acre returns. Under such conditions it is 

 often feasible to install special irrigation devices, such as 

 sprinkling from permanently fixed pipes or from the nozzles 

 of movable hose. Such methods are wasteful of invest- 

 ment, labor and water and are practically out of the ques- 

 tion for large areas. Sub-irrigation also is advocated under 

 humid conditions, but the arguments already urged against 

 sub-irrigation, unless natural, hold under humid condi- 



