IRRIGATION 275 



longer irrigation period than small grains, therefore requires more 

 water. Cultivation alter each irrigation, is very essential. An appli- 

 cation of 25 inches gave !)!>.! bushels per acre at the Utah Station. 



Rice is a crop that is grown under humid, semi-tropical con- 

 ditions, but irrigation or flooding is necessary The check system is 

 used. Levees are thrown up sufficiently high to retain a layer of 

 water to a depth of three to ten inches. The water is nearly always 

 applied by pumping from wells or canals. 



Forage Crops. Alfalfa is not only the most important crop for 

 forage purposes, but it is the most valuable of all crops grown 

 under irrigation (Fig. 12(>). Its value is enhanced by the fact that 

 it is a nitrogen gatherer and actually builds up the soil during its 

 growth. 



Water may be applied by furrows, flooding, or by checking. 

 When water is abundant flooding is the method used. If the soil 

 bakes or tends to run together, the furrow method is preferable. In 

 this case the land is marked off or furrowed immediately after seed- 

 ing and the furrows become permanent. Alfalfa requires somewhat 

 more water than cereals, and 18 to 24 inches should be applied. 

 Fortier found that 30 acre-inches applied to one acre produced 

 14,400 pounds of hay. while when the same amount of water was 

 applied to five acres (54,100 pounds were produced. 



If seed is to be produced but little water should be applied to 

 the growth that is to produce the seed. 



Olhcr Forage Crop*. Timothy, orchard yraxs and bronic ///v/.w 

 are crops that thrive under irrigation, but are very inferior to 

 alfalfa in this respect. Clover does well under irrigation, but pro- 

 duces much less hay than alfalfa. 



The sugar beet is one of the most profitable of irrigated crops. 

 It prefers a deep clay loam soil and dry summers. Three to five 

 irrigations are sufficient and on some soils only t\vo are deemed 

 necessary. From four to six inches are applied at each irrigation. 



Potatoes are a very important crop on irrigated land. Their 

 water requirements are somewhat like sugar beets. The furrow 

 method is practiced. Fifteen to twenty-four inches of water should 

 I'e sufficient. 



Peas, beans, melons, tomatoes, onions, cotton, and manv 

 other crops may be grown very successfully under irrigation. 



Fruits of nearly all kinds may he grown where climatic con- 

 ditions are right. 



Irrigation in Humid Climates. An annual precipitation of 



