PHYSICAL AND CLIMATIC SETTING 55 



determinate factors in success is the summer rainfall 

 and curves showing the total rainfall in the summer 

 season and the yield of hay and corn correspond very 

 closely. Departures from the normal weather ele- 

 ments are large and in the case of rainfall raise the 

 question of the practicability of irrigation. This de- 

 pends on the actual frequency and extent of variation 

 of the rainfall, the nature and value of the crops and 

 the cost of applying water. In general, irrigation 

 will be practicable only on crops of high acre value 

 and then only on the coarser soils of low moisture ca- 

 pacity. 



