354 



SOIL PHYSICS AND MANAGEMENT 



there in larger numbers, attracted by the favorable conditions for 

 obtaining food and moisture. An examination will show many of 

 the roots of cultivated plants within the surface three inches of 



Fio. 170. Yields of corn (field weight) with different methods of tillage. (1911) 



soil under favorable conditions and probably three-fourths of the 

 roots of the plants within the surface or plowed soil. 



Fio. 171. Yield of corn (field weight) with different methods of tillage. 



To preserve these roots from injury very shallow cultivation 

 must be practiced. Roots take nourishment from the soil for the 

 plant and if roots are cut off it lessens the food supply. Not only 

 this, but it takes energy from the plant to reproduce the roots de- 



