232 



Irrigation and Drainage 



underlaid by a reddish clay subsoil, which changed 

 through a sandy clay into a mixed sand and gravel, 

 at 4 or more feet. His photographs, reproduced in 

 Figs. 38, 39, 40 and 41, show to what extent the roots 

 of these fruits penetrate the soils and subsoils of 



ft 



Fig. 41. Penetration of roots of strawberry in matted rows in Wisconsin 

 soil. Depth 22 inches. (Goff.) 



Wisconsin, where the annual rainfall ranges from 28 

 to 40 inches. It will be seen from the legends that 

 the roots of the apple have extended to a depth of 

 fully 9 feet, the grape more than 6, and the raspberry 

 more than 5. It is plain, therefore, that even in the 

 soils of humid climates the roots penetrate so deeply 

 that the moisture of the surface 8 to 10 or 12 feet is 



