The Soil: Its Use and Abuse 



1355 



and thorough knowledge of all the processes and operations involved in 

 producing crops from the soil than is possible by the older " rule of thumb " 

 method. So broad are the relationships of good soil management that 

 no person may properly claim the right to be exempt from a certain fun- 

 damental knowledge of the soil and its conservation, however far he may 

 be removed professionally. 



THE NATURE OF THE SOIL 



The soil material — the superficial area of the earth — is so thin as to 

 be infinitesimal in thickness when compared with the diameter of the earth. 

 We commonly define the soil as the surface area of the earth's crust that 



Fig. 3. — The water from the melting of ice at the front of a glacier carries away and sorts 

 the rock materials and deposits them along its course, later to serve as soil. Much of the 

 land along the lakes and through the valleys in New York has been formed in this way 



is capable of supporting plant growth. The growth that it will support 

 may be ever so simple, as in the case of a few bacteria on some rock clifif, 

 or it may be a tall field of corn on a rich river plain, or a dense forest of 

 trees on a fertile plateau. 



We include in the soil all the material to the depth to which plant 

 roots are able to distribute themselves. It therefore includes a wide 

 range of material in depth and character. It may be deep or shallow, 

 coarse or fine, loose or compact, light or dark, wet or dry. It is all soil 

 because it is a medium for the growth of some kind of plant. In general, 

 the soil may be divided into two classes of material: (a) the particles 

 of mineral and fragments of rock, and (b) bits of organic matter of both 

 plant and animal origin that have become more or less decomposed. 



