Soils 59 



difference between the surface and the subsoil is not great, 

 the subsoil being in many cases just as fertile and mellow 

 as the upper layer. In humid regions, on the other hand, 

 the subsoil is often compact and, on account of its lack 

 of aeration, seems "dead" when brought to the surface. 

 Such soils sometimes require a number of years to be- 

 come fertile. Sugar-beets, on account of their deep pene- 

 tration of roots and their high air requirement, find their 

 best growth only in soils having a subsoil condition that 

 is favorable. Any hardpan layer is particularly detri- 

 mental. 



SOIL TEXTURE 



Soils vary greatly in the size of particles composing 

 them. Some are made up almost entirely of coarse parti- 

 cles; others are composed entirely of fine. Most soils, 

 however, contain some fine and some coarse grains, the 

 relative number of each determining the texture, which 

 cannot be modified by the farmer. The texture of the 

 soil has a great influence on the method of tillage as well 

 as on a number of its properties, such as the water-hold- 

 ing capacity, the circulation of air, and the availability 

 of plant-food. These all help in determining the kind 

 of crop that should be grown. For example, peaches and 

 cherries thrive on a soil having a coarse texture ; the small 

 grains prefer a " heavier " soil ; sugar-beets and most other 

 crops do best on soils of intermediate texture, such as the 

 loams. 



The various sizes of particles composing the soil have 

 been classified by the United States Department of 

 Agriculture, Bureau of Soils, as follows : 



