CHAPTER IV 

 SOILS IN DRY AREAS 



The discussion of soils in dry areas will be essentially 

 popular in kind. The attempt will not be made to classify 

 these soils on what may be termed a strictly scientific 

 basis. They will be discussed on the basis of the popular 

 conception of their leading characteristics. Hillgard. 

 suggests the following classifications: (1) soils very 

 sandy; (2) ordinary sandy soils; (3) sandy loams; (4) 

 clay soils, and (5) heavy clay soils. The first of these 

 has from 0.5 to 3 per cent, of clay ; the second 3.0 to 10.0 ; 

 the third 10 to 15 and the fourth 15 to 35. The present 

 discussion will regard them as: (1) clay; (2) sandy; (3) 

 silt ; (4) volcanic ash ; (5) gumbo, and (6) alkali. It will 

 be preceded by the consideration of some of the 

 characteristics peculiar to western soils and subsoils 

 and followed by the discussion of natural production as 

 an index of soils. 



Some characteristics of western soils. The -soils in 

 dry areas frequently differ from those in humid areas : (1) 

 in color; (2) in their mineral constituents; (3) in the 

 supply of organic matter, and (4) in their moisture- 

 holding power. In other respects they may be similar 

 to the latter, as in their physical constituents. 



The average soil of the Mississippi valley is dark in 

 its color. This is essentially the outcome of the large 

 amount of organic matter which it contains in one or 

 the other of its forms. One who is familar only with 

 such soils, looks suspiciously on those of the semi-arid 

 west. He is much prone, to conclude that they are lack- 

 ing in fertility and that they are also difficult to till. 

 These conclusions are far from correct. These soils, which 

 are usually brown in color, with variations, of course, that 

 are lighter and darker, are much richer in the essential 



