72 CULTIVATION AND TILLAGE 



in the subsoil by translocation. The best means of pre- 

 venting the loss of water is by cultivating the ground with 

 implements that will break up the soil as soon as possible 

 after a rain has fallen. Such a cultivation at the proper 

 time will leave the surface in a fine condition and will check 

 the evaporation of water from the ground. 



If the subsoil contains an ample amount of water, and 

 there is a minimum amount in the surface soil, a movement 

 of the subsoil water after a rain frequently occurs. This 

 movement is brought about by the capillarity of the soil, 

 and the surface tension of the film of water about each soil 

 particle becomes greater with the increase of the water in 

 the surface soil. 



Fig. 19. — A general purpose plow. (International Harvester Company 

 of America.) 



Spring Versus Fall Plowing. — Plowing is the process of 

 breaking up the soil and reducing it to a finer state of divi- 

 sion. Much depends upon this process. The difference 

 between loss and gain is sometimes found in the time a 

 soil is plowed. This difference is made possible because 

 the water-holding capacity of a soil is regulated largely by 

 the state of fineness to which it is reduced. It is a well- 

 recognized fact that crops cannot grow and develop with- 

 out the proper amount of water. This water is increased 

 if the plowing is done at the proper time and the water 

 content can largely be controlled in this manner. 



Certain types of soil will admit of fall plowing and they 

 will be greatly improved both in their physical proper- 

 ties as well as in their water-holding capacity. Soils that 



