110 



THE PRINCIPLES OF AGRICULTURE 



SUGGESTIONS ON CHAPTER VII 



170a. Tap-roots (Fig. 33) extend the benefits of root aotfon 

 to great depths. They drain, aerate and comminute the soil; 



Pig. 33. The deep root-system of 

 red clover. 



Fig. 34. The shallow root-system 

 of orchard grass. 



and the plant-food which they bring from the subsoil is left, 

 when the plant decays, in such place and condition that sur- 

 face-rooted plants can get it. With the clover, compare a 

 grass (Fig. 34). 



171a. In many countries definite efforts are made to hold 



