most areas before Man developed the art of producing more 

 subsistence from a given area by tilling the soil. When the 

 drops of rain reach the earth they first strike the trees and 

 bushes, or the herb and grass cover of the soil. The water 



PRECIPITATION 



EVAPORATION 



TRANSPIRATION 



UTTER AND 

 HUMUS 



HUMIFIED 

 SOIL 



ROOT 

 ZONE 



SUBSOIL 

 STORAGE 



ROCK 



Figure 9. 



then trickles through the grass and is absorbed by the loose 

 soil about the grass roots; or, after dropping from the trees 

 and bushes, filters through any forest litter and is absorbed 

 by the loose soil underneath the trees and bushes. When this 



