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. 



Kind of crop 



Year 



Yield per acre; 

 not irrigated 



Amt. of 



sewage 



water 



applied in 



irrigation 



Yield per acre 



irrigated 



area 



Increase 

 yield per 

 A. by irri- 

 gation 



Cabbage 



Corn 



Barley 



Rye grass 



Beets, sugar .... 



Potatoes 



Barley 



Alfalfa 



Blue grass 



Timothy 



Beets 



1907 

 1907 

 1907 

 1908 

 1908 

 1908 

 1909 

 1909 

 1910 

 1910 

 1910 



63840 lbs. 

 57.8 bu. 

 41.4 bu. 

 3.15 tons 

 11.25 tons 

 150.2 bu. 

 29. bu. 

 6.67 tons 

 .13 tons 

 1.42 tons 

 39.1 tons 



7 in. 

 7 in. 

 13.21 ft. 

 5.41 ft. 

 7.08 ft. 



70430 lbs. 

 59.8 bu. 

 54. bu. 

 3.49 tons 

 12.75 tons 

 181.5 bu. 

 34. bu. 

 5.6 



1.32 tons 



3. tons 



59. tons 



9.5% 

 3.4% 

 30.4% 

 10.7% 

 13.3% 

 20.8% 

 17.2% 

 —16.0% 



111.2% 

 50.9% 





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. 



