196 



SOILS AND PLANT LIFE 



young corn to bury the tiny weeds and to prevent evapo- 

 ration of moisture. 



As the corn becomes larger, the discs are reversed and 

 the soil is drawn by successive cultivations about the 

 roots of the plants. Shovels are usually substituted for 

 the discs at the second and later cultivations. 



134. Harvesting the Crop. — One of the peculiarities 

 of every food-producing plant is that as food material 



Cutting corn with a binder. 



is stored in the seed, other parts of the plant become 

 graduallj- woody and indigestible. 



In the case of corn, for example, we find that while 

 the amount of dry matter in the plant increases steadily 

 until the crop is nearly or quite mature, the amount of 

 digestible matter increases only until the kernels become 

 glazed over and diminishes quite rapidly thereafter. Thus 

 the mature plants on an acre, yielding sixty bushels of 



