122 DRY FARMING 



91. Why We Till Prairie Sod.— The function of tilling 

 prairie sod in semi-arid climates is threefold: 



1. To store and conserve moisture in the soil. 



2. To kill the native vegetation, and 



3. To prepare a suitable seed bed. 



92. How Moisture is Stored and Conserved in New Lani. 

 —The storage and conservation of moisture is necessary 



Fig. 44. — Breaking with Tractor. 



No skips or misses but land too dry for a smooth job.— Courtesy 

 Dominion Experimental Farms. 



before profitable crops can be raised on new land. This 

 is accomplished by (1) killing the native vegetation 

 early in the growing season, (2) by preventing the "run- 

 off'', and (3) by preventing the excessive drying out of 

 the furrow slice. 



All prairie land is covered with a growth of grass and 

 other plants native to the district. These use up moist- 

 ure in just as large quantities as weeds or domestic 

 crops. (See Sec. 168). Most of them make their greatest 



