CHAPTER VII 



SOILS AND THEIR USES 



Whoever will be perfect in the science of agriculture must be well 

 acquainted with the qualities of soils and plants, and must not be ignorant 

 of the various climates, so that he may know what is agreeable and what is 

 repugnant to each. COLUMELLA. 



ALL elements or substances found in plants or animals are 

 from either the soil or the air. Plants are produced from the soil 

 and air; animals, in turn, secure their food from plants. The 

 grower of field and garden crops is interested directly in soils; and 

 the stock raiser is only slightly less interested in them. Both must 

 know what kinds of soil are best for their special lines of farming. 



What the Soil Really Is. Soil has often been defined as the 

 surface part of the earth in which crops may grow; but this gives 

 us very little idea of its real nature. To understand it better let us 

 follow the suggestion of I. P. Roberts and put a sample of good 

 black soil to different tests. It will usually be found to contain 

 insect life and other animal life in different forms. The bacteria 

 present are not only abundant but are of too many kinds to be 

 all known by the bacteriologist. Seeds and spores are usually 

 present in countless numbers. The dark color is chiefly due to 

 the presence of decayed organic matter the result of both animal 

 and vegetable matter which has begun decay soon after death. 

 Much moisture is there and with it different chemicals in suspen- 

 sion. Oxygen, nitrogen and other gases constitute the air of the 

 soil. The greatest bulk is probably made up of particles of clay 

 and sand which have resulted from the disintegration of rocks 

 through the long ages past. 



In the study of soil, formation through the crumbling of rocks 

 of different kinds, a student must not lose sight of the real nature 

 of soil and the multitude of organisms and substances in it. 



The best farm soil is made up of a proper mixture of sand, clay, 

 and decaying organic matter called humus, in just the right pro- 

 portions. With it must be plenty of moisture in the best form. 

 It must be in such physical condition as to allow the proper degree 

 of ventilation for the supply of oxygen and the removal of injuri- 

 ous gases, and to supply heat at the proper seasons. It must 

 have an abundant supply of useful bacteria and similar organisms. 



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