SOILS IN DRY AREAS 69 



these particles may adhere to one grain, and in so far 

 as they do they lessen the tendency to leaching. 



Sandy loam soils and also sandy soils cover much of 

 the surface of the semi-arid areas. In the eastern portion 

 of this area these are usually sectional, and in some in- 

 stances the silt particles in them are so light that they 

 lift more or less with the wind. In the Inter-mountain 

 region these areas are more pronounced. In some parts 

 of the valley of the Columbia they cover wide areas, 

 and the same is more or less true of the Big Basin coun- 

 try. In many instances sandy soils maintain but little 

 growth while yet untilled, hence oftentimes they have 

 a barren aspect. 



In dry areas sandy loam soils are among the best, 

 whether viewed from the standpoint of production or 

 from that of tillage. These soils encrust and compact 

 less readily than other soils and they do not lose water 

 so readily by evaporation. They may be tilled at al- 

 most any season of the year not locked with frost. They 

 warm more quickly in the spring, and are therefore more 

 favorable to early growth. Their value, however, is 

 much influenced by the degree of the clay which they 

 possess. When too lacking in clay or silt particles, they 

 become leachy. 



* Silt soils. Silt soils are composed of soil grains that 

 have been deposited mainly through the action of wa- 

 ter. The particles of which they are composed are usu- 

 ally small and fine, much smaller and finer than the 

 average sand particles and larger than the particles of 

 clay soils. They are of varying degrees of fineness, de- 

 pendent on the extent of the reduction of the sand par- 

 ticles which compose them. In some instances they are 

 possessed of much uniformity in texture, and this may 

 extend to a great depth. In other instances they are in- 

 termixed with gravel more or less coarse and they are 

 not infrequently underlaid with a subsoil of coarse gravel 



