SOIL RELATIONS 243 



portion of the Republic, altitude, aridity, and humus 

 progress westward toward the mountains, as in the Great 

 Plains. 



255. Prairie and steppe cover. Grasses are the chief 

 native vegetation in prairie regions. In the Chernozem 

 a common species is the feather grass (Stipa pennata), 

 and the name " Feather Grass Steppe " is, consequently, 

 often applied to portions of it. In the Great Plains 

 feather grasses are also frequent, but the principal species 

 are blue-stems in the eastern, and gramma and buffalo 

 grasses in the western portion. 



256. Chemical composition of prairie soils. Many 

 analyses of Chernozem soils are reported, of which an 

 important series was made by Schmidt with samples 

 collected by Dokuchaev. Of the Great Plains soils, 

 analyses were made by Ladd of samples from two 

 points in the James River Valley and from Minot 

 and Sykeston, all in North Dakota. About the only 

 analyses of samples from the Canadian area of the 

 Great Plains were made by Shutt and Alway (1909). 

 From what depth Shutt's samples were taken is not stated. 

 The samples analyzed by Alway were taken from a ten- 

 acre fallow field on the Experimental Farm at Indian Head, 

 Saskatchewan, in November, 1904, which field produced 

 over 46 bushels to the acre of oats in 1905. These an- 

 alyses, being made by different parties on different bases, 

 do not, in some places, exactly harmonize, but all show 

 large to very large percentages of potassium, calcium, 

 and phosphorus, a large proportion of humus, and great 

 water-holding capacity. Often there is also a good per- 

 centage of magnesium. 



257. Mechanical analyses of prairie soils. The 

 fact that prairie soils are composed of a large proportion 



