360 IRRIGATION PRACTICE 



If the volume is very small, too large a proportion of the 

 water is lost by evaporation during the long time required 

 to cover the land with water. The method of continuous 

 flow, which means that a stream of the same volume 

 enters the farm from the beginning to the end of the irri- 

 gation season is successful only if the stream has a suffi- 

 cient head, say from 1 to 2 second-feet. If smaller than 

 this the method of continuous flow is not usually satis- 

 factory. A large farm of from 100 to 300 acres may 

 utilize so large a continuous stream. On small farms with 

 small water supplies, the method of continuous flow is 

 utterly unsatisfactory. A chief objection, even on large 

 farms, to the method of continuous flow, is that, under it, 

 irrigation must always be going on. The method of con- 

 tinuous flow is of real value only when the farm is a mini- 

 ature complete irrigation system, representing the diver- 

 sity of crops and conditions under the whole canal system; 

 for only when this condition exists can the water be used 

 to advantage from the beginning to the end of the season. 

 There is always more land than water in the irrigated 

 sections. A man having a continuous stream of water 

 throughout the season would probably plant one-half of 

 his farm to grains N and other early-maturing crops, and the 

 other half to potatoes, beets or other late-maturing crops. 

 In the early season the water would be used chiefly on the 

 early crops; in the later season on the later crops. By such 

 methods, the continuous flow may be made to cover larger 

 areas than can the intermittent method. In practice, the 

 distribution of water by continuous flow is carried on as 

 follows: Ten second-feet are carried by a canal for the 

 use of 1,500 acres divided into several farms. Laterals 

 are made to each farm, in which is carried the proper pro- 

 portion of water for that farm. Thus, a farm of 150 acres, 



