86 DRY-FARMING 



ures 22-26 further give an idea of the degree to 

 which roots fill the soil. 



Depth of root penetration 



The earlier root studies did not pretend to deter- 

 mine the depth to which roots actually penetrate 

 the earth. In recent years, however, a number of 

 carefully conducted experiments were made hj the 

 New York, Wisconsin, Minnesota, Kansas, Colorado, 

 and especially the North Dakota stati(_)ns to obtain 

 accurate information concerning the dej^th to which 

 agricultural ])lants j^cnetrate S(jils. It is some- 

 what regrettal)le, for the purpof^e of dr3'-farming, 

 that these states, with the exception of Colorado, 

 are all in the humid or sub-humid area of the United 

 States. Nevertheless, the conclusions drawn from 

 the work are such that the}' ma}' be safeh' applied 

 in the development of the principles of dry-farming. 



There is a general belief among farmers that the 

 roots of all cultivated cro]:>s arc very near the surface 

 and that few reach a greater dej^th than one or two 

 feet. The first striking result of the American inves- 

 tigations was that every crop, without exception, 

 penetrates the soil deeper than was thought possible 

 in earlier days. For example, it was found that 

 corn roots penetrated fully four feet into the ground 

 and that they fully occupied all of the soil to that 

 depth. 



