CHAPTER III 



DRY-FARM AREAS. RAINFALL 



The annual precipitation of rain and snow deter- 

 mines primarily the location of dry-farm areas. 

 As the rainfall varies, the methods of dry-farming 

 must be varied accordingly. Rainfall, alone, does 

 not, however, furnish a complete index of the crop- 

 producing possibilities of a countr}'. 



The distribution of the rainfall, the amount of 

 snow, the water-holding power of the soil, and the 

 various moisture-dissij^ating causes, such as winds, 

 high temj^crature, abundant sunshine, and low humid- 

 ity, freciuently combine to offset the benefits of a large 

 annual precipitation. Nevertheless, no one climatic 

 feature represents, on the average, so correctly 

 dry-farming ])ossibilities as does the annual rainfall. 

 Experience has already demonstrated that wherever 

 the annual precipitation is above 15 inches, there is 

 no need of crop failures, if the soils are suitable and 

 the methods of drj'-farming are correctly employed. 

 With an annual precipitation of 10 to 15 inches, 

 there need be very few failures, if proper cultural 

 precautions are taken. With our present methods, 

 the areas that receive less than 10 inches of atmos- 



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