CHAPTER II 

 SOILS AND FERTILIZERS 



SOIL 



SOIL is chiefly decomposed and disintegrated or 

 crumbled up rock. The main decomposing and disin- 

 tegrating agencies are air, rain, ice, and winds. These 

 agencies are aided by heat and chemical action. The 

 topsail extends only a few inches below the surface of 

 the ground, but the subsoil underneath it varies in 

 depth from a few feet to a hundred or more feet. 



Kinds of Soil as to Mechanical Composition. A* 

 soil made up of very fine particles, so fine that the 

 separate particles can be distinguished only by the help 

 of a microscope, is called a clay soil ; a soil made up of 

 particles in the form of grains is called sandy soil. 

 A clay soil is usually sticky when wet, does not disin- 

 tegrate readily on drying, and is hard to work, while a 

 sandy soil permits moisture to pass off readily and is 

 not sticky. Silt is soil made up of particles intermediate 

 in fineness between sand and clay. 



There is no so-called clay soil that does not contain 

 some granular particles. The ordinary soils as we find 

 them are mixtures of clay, sand, silt, and humus. This ' 

 may be readily seen by putting a small quantity of ordi- 

 nary soil in^ bottle partly filled with water and shaking 

 it thoroughly. When it is allowed to stand the coarser 



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