218 FIELD, FOREST AND FARM 



land. Wherever the soil is too clayey, or even where 

 the surface soil is good but the subsoil clayey, rain- 

 water cannot drain off readily and the ground re- 

 mains soggy and cold. Eventually, however, it dries 

 up, but there being no way for the air to permeate 

 the soil, the latter is left hard and unyielding, so 

 that the roots are by turns drowned in liquid mud 

 and held fast in a tenacious paste that has been 

 baked by the sun. Drainage overcomes these diffi- 

 culties, and consequently all rich soils that hold rain- 

 water for some time before infiltration are much 

 improved by being properly drained." 



