IRRIGATION 



139 



include grasses, grains, potatoes and garden truck. Of 

 these, grasses is the most generally grown; Italian rye grass, 

 especially, thrives under this form of irrigation. The success 

 of sewage irrigation indicates that it could be practiced more 

 generally than it is at present. 



For several years, experiments in sewage irrigation were 

 conducted at the Iowa experiment station, in co-operation 

 with the irrigation investigations of the United States Depart- 

 ment of Agriculture. The following table is a summary of a 

 part of the results obtained. Two plots of each crop were 

 grown under the same conditions, except that one was irri- 

 gated with sewage water and the other was not irrigated at all. 



Summary of irrigation experiments in Iowa, showing increased yields by 

 the use of sewage water. 



During the years 1907 and 1908, irrigation was given 

 only when the crop seemed to be in need of moisture. In 

 1910 a larger amount of water was used. 



