THIRD ANNUAL YEAR HOOK PART VI. 



261 



soil by making it finer and looser, thereby affording a larger feeding area 

 for the roots of the plants. Chemical improvement is brought about 

 by admitting a larger quantity of air into the soil. This process in- 

 creases the fertility by hastening the formation of available plant food. 

 An adequate supply of moisture is an essential condition for the growth 

 of corn. The amount of water used by the corn crop during the grow- 

 ing season is enormous. An idea of the total moisture needed is gained 

 from the fact that 310 pounds of water are required for every pound of 

 dry matter. During the hot summer months, the period of the least, 

 rainfall, the growing crop requires the major part of this vast quantity 



French Coach Stallion owned by Carroll French Coach Horse Co., Carroll, 

 Iowa, and shown at Iowa State Fair, 1902. 



of water, and it is during this time that the great reserve supply of 

 moisture in the soil finds its way to the surface by capillary attraction 

 and evaporates rapidly. Now the point is, will the corn grower permit 

 the loss of water which sustains such a vital relation to his crop? He 

 need not permit it, for this evaporation can be retarded by stirring the 

 surface of the soil and keeping it light and porous, the loose soil serving 

 as a mulch. The pores in this soil are far too large for capillary action 

 and the moisture fails to reach the surface. The corn grower, then, 

 must cultivate more frequently, and less deeply, too, as; we shall find, 

 in order that while killing the weeds, he may preserve the moisture 

 for the corn roots and spare the corn roots to gather the moisture 



