KINDS OF SOILS— THEIR CHARACTERISTICS 51 



than on clay, if enough plant food is provided. Compact 

 and sticky soils produce poor crops in wet seasons. The 

 farmer finds it easy to plow and cultivate a sandy field. It 

 is adapted to quick-growing crops, such as early vegetables; 

 and sweet potatoes do well on such a soil. It may be culti- 

 vated without injury when wet. When it lies over clay 

 under-soil or subsoil it may have a high degree of fertility. 





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Fig. 30. — Peach trees in rocky soil. After the soil is plowed, the rains soon wash 

 the fine soil away through the top of the rocks and leave the surface as shown in the 

 picture. The roots of trees are in the finer parts of the soil and the growth is good. 

 (Experiment Station, N. J.) 



Clay Soil. — Clay soil is much more finely divided than 

 sand. When wet it is plastic and sticky. The latter property 

 makes it useful for making bricks and tiles. Some farm soils 

 are largely clay; but clay alone does not make a good farm 

 soil and its plant-food is not readily available. 



Soil composed of as much as forty per cent of clay may 

 be good farm soil, and may be well adapted to the growth 

 of grains and grasses. It should not have over fifty per cent 

 of clay present. The finely divided particles of clay adhere 



