108 THE POTATO 



This method is in general suitable for medium 

 slopes, soils which do not bake, grain pasture and 

 hay crops, and where lands are not of great value, 

 such as meadow lands at high altitudes. One 

 man can irrigate from two to five acres a day. As 

 a rule the irrigation by this method is more un- 

 even than with the other system. 



"Some system to care for waste water is a nec- 

 essary part of an irrigated farm. Especially 

 where the ranch is bordered by other irrigated 

 tracts or by public roads it is essential to have an 

 adequate system of waste ditches that will re- 

 ceive and care for whatever water is not used by 

 the irrigation. It often happens that draws or 

 coulees are so located that they will carry away 

 the waste water and in such cases no further at- 

 tention is necessary. The amount of waste water 

 is so variable that it is seldom satisfactory for 

 any one else to try to use it for irrigation, and be- 

 cause of the fluctuations in its flow is not best to 

 waste the water into another farm ditch. 



**The term 'duty of water' as used in irrigation 

 is accepted to mean the acreage of land that a 

 certain amount of water should sufficiently ir- 

 rigate. The standard measurement for running 

 water is in cubic feet per second — that is, a run- 

 ning stream is measured by the number of cubic 

 feet which pass a given point per second. In 

 Idaho a miner's inch of water is one fiftieth of a 

 cubic foot per second. The amounts used in ir- 

 rigation are commonly spoken of in acre feet or 

 acre inches. This is the amount covering an 

 acre of land one foot deep or one inch deep as the 

 case may be. 



"The amount of water needed to grow and ma- 

 ture a crop is dependent on a great variety of 



