THE POTATO 387 



proverbial that **a limestone country is a rich 

 count^}^" The average per centage of lime in 

 clay soils is .617. In the lava ash soil of the 

 Twin Falls North Side tract there is 4.5 per cent. 

 x\n acid soil is almost invariably a hard soil to grow 

 crops on. As a general statement, all good soils 

 show an alkali reaction — that is, they contain more 

 alkali salts than acids. 



The fact that the soil of the Snake River plains 

 IS partly an seolian or wind deposit classes it with 

 the richest soils in the world. It is the deposits 

 of the dust of ages swept from a desert country in 

 addition to the lava dust from volcanic eruptions. 

 The fine particles of soil are those from which the 

 rootlets of the plant obtain their chief food supply. 

 The Twin Falls North Side soil classes as 100 per 

 cent. fine. In the regions embracing these fine, 

 rich deposits there are dust storms while the coun- 

 try is a desert, but after irrigation and cultivation, 

 with the consequent filling of the soil with moisture 

 and vegetation, dust storms do not occur. The 

 great plains of North America, including a large 

 part of the Mississippi Valley, is a wind deposited 

 loess or loam. The fertile loess soil region in 

 northwestern China, which supports a dense 

 population, is of seolian origin. The soil of the 

 Twin Falls country consists of a mixture of the 

 finest particles of the deposits from the disintegra- 

 tion of the rock of the mountains and plains, the 

 wash of the same, and dust blown off the lake de- 

 posits to the west and south. 



The altitude of the Twin Falls country is from 

 2,800 to 4,800 feet. It Hes just south of the 43d 

 degree of north latitude, almost centrally north and 

 south in that section around the globe in which has 

 been made the major part of the world's prog- 



