Natural Fertility of the Soil 19 



purchased in the form of commercial fertilizers. This 

 estimate is certainly conservative, and clearly demon- 

 strates the serious drain upon our resources of fertility ele- 

 ments, due to the lack of care in the handling of farm 

 manures. 



The conditions, as here pointed out, not only suggest 

 the need of imported plant-food, but that there are oppor- 

 tunities for reducing this need by careful saving and use 

 of the constituents that are subject to waste. 



