230 



Irrigation and Drainage 



from the photograph, to have destroyed nearly all but 

 the main trunks, unless it was true that the active 



Fig. 39. Penetration of grape roots in Wisconsin soil. 

 Depth 6 feet. (Goff.) 



absorbing surfaces were chiefly still more deeply buried 

 in the soil than the excavation extended. This appears 

 quite likely to have been the case, for this penetra- 



