CH. ii] Plough Soles and Pans 35 



ing to the same depth ; the weight of the plough pressing 

 on the bottom of the furrow causes a certain amount of 

 consoHdation which in course of time becomes very- 

 mar ked. 



In soils where water is near the surface a layer of rock 

 known as a pan sometimes occurs. It is formed by the 

 precipitation of soluble material through a process similar 

 to the formation of certain jeUies. 



Plough-soles and pans should be broken by occasional 

 deep cultivation so as to allow free movement of the 

 water and deep development of plant roots. 



32 



