74 DRY-FARMING 



Soil divisions 



The dry-farm territory of the United States may 

 be divided roughly into five great soil districts, each 

 of which includes a great variety of soil ty])es, most 

 of which are poorly kn(jwn and mapped. These 

 districts are : — 



1. Great Plains district. 



2. Columbia River district. 



3. Great Basin district. 



4. Colorado River district. 



5. California district. 



Great Plains district. — On the eastern slope of 

 the Rocky ^lountains, extending eastward to the 

 extreme boundary of the dry-farm territory, are the 

 soils of the High Plains and the Great Plains. This 

 vast soil district belongs to the drainage basin of the 

 Missouri, and includes North and South Dakota, 

 Nebraska, Kansas, Oklahoma, and jiarts of ^ion- 

 tana, Wyoming, Ojlorado, New i\Iexic(3, Texas, and 

 Minnesota. The soils of this district are usually of 

 high fertility. They have good lasting po'\\'er, 

 though the effect of the higher i-ainfall is evident in 

 their composition. Many of the distinct types of 

 the plains soils have been determined with consider- 

 able care by Snyder and Lyon, and may be found 

 described in Baile>''s "Cyclojjedia of American Agri- 

 culture," Vol. L 



Columbia River district. — The second great soil 



