186 THE FARMER OF TO-MORROW 



The resources of the soil are the one im- 

 mutable asset of the nation. They can be im- 

 paired by abuse, but never destroyed. 



If by any chance he encounters this 

 hypothesis, it will only serve to puzzle him the 

 more, so thoroughly soaked is he in the doc- 

 trines that have actuated the teachings in 

 agriculture and established the chemical fer- 

 tilizer industry. The chances, however, are 

 that he has not heard of this theory, or, if he 

 has, that it has been laughed out of his head 

 by his neighbors' sons who are home from 

 college where they received farm training, and 

 anticipate practicing teaching according to 

 Liebig. It was first announced by the United 

 States Department of Agriculture in 1908. 

 We will examine it in detail later. It is suffi- 

 cient to say now that China, after forty cen- 

 turies of intensive farming, such as even 

 western Europe does not practice, has not yet 

 learned the use of, or even acknowledged the 

 necessity for chemicals as "plant food." 



If, as the accepted hypothesis of soil re- 

 sources states, the number of crops that can be 

 taken from a given cubic foot of soil can be 

 ascertained mathematically, simply by dividing 



