262 



IRRIGATION PRACTICE 



second-foot, flowing for ninety days, will cover 180 acres 

 to a depth of 12 inches. This corresponds closely to the 

 duty of water as given for wheat. As in the case of the 

 small grains, the duty for corn is steadily increasing. 



FIG. 66. Irrigated corn in Arizona. 



164. Rice. Rice is a semi-tropical plant, best devel- 

 oped in moist climates. Certain varieties of upland rice 

 thrive in dry climates, but these are practically unknown 

 in the United States. The rice of commerce requires 

 moist conditions, and, therefore, heavy irrigation. It is 

 grown chiefly on the delta and marsh lands of the South 



