CHAPTER II 

 The Fertility of the Common Fields 



Up to this point attention has been given chiefly to the 

 theory that the enclosure movement waxed and waned in 

 response to supposed fluctuations in the relative prices of 

 wool and grain, and it has been found that this theory is un- 

 tenable. It is now necessary to consider more closely the 

 true cause of the conversion of arable land to pasture^^the 

 declining productivity of the soil — and the cause of the 

 restoration of this land to cultivation — the restoration of 

 its fertility. 



The connection between soil fertility and the system of 

 husbandry has been explained by Dr. Russell, of the Rotham- 

 sted Experiment Station : 



Virgin land covered with its native vegetation appears to alter 

 very little and very slowly in composition. Plants spring up, 

 assimilate the soil nitrates, phosphates, potassium salts, etc., 

 and make considerable quantities of nitrogenous and other or- 

 ganic compounds : then they die and all this material is added to 

 the soil. Nitrogen-fixing bacteria also add to the stores of 

 nitrogen compounds. But, on the other hand, there are losses : 

 some of the added substances are dissipated as gas by the de- 

 composition bacteria, others are washed away in the drainage 

 water. These losses are small in poor soils, but they become 

 greater in rich soils, and they set a limit beyond which accumu- 

 lation of material cannot go. Thus a virgin soil does not be- 

 come indefinitely rich in nitrogenous and other organic com- 

 pounds, but reaches an equilibrium level where the annual gains 

 44 . [200 



