Depth of Root Penetration 



229 



its needs in a dryer soil, it is evident that a much 

 higher duty of water is possible, for the simple reason 

 that none can be lost by percolation, and much less 

 will be lost by surface evaporation, even with deficient 

 tillage. 



We have already called attention to the probable 

 deeper rooting of plants in soils of arid regions, where 



Fig. 38. Penetration of apple root in Wisconsin, 7 years planted. 

 Depth 9 feet. (Goff.) 



there is less distinction between the soil and subsoil, 

 than in those of humid climates. Since writing that 

 section, we have received Professors Hilgard and 

 Loughridge's Bulletin 121, in which they emphasize 

 this point by placing in evidence a photo -engraving 

 of a prune tree on a peach root exposed in the soil 

 to a depth of 8 feet, and represented in Fig. 37. The 

 method they have used in exposing the root appears, 



