THEORY OF SOIL FERTILITY 177 



fertilization, and yearly the amount was grow- 

 ing, due to the teachings of the officially es- 

 tablished federal and state agricultural ex- 

 periment stations. The nations of western 

 Europe were using even more chemicals for 

 crop production than America. At length 

 economists, whose faith in the theory of ulti- 

 mate doom is guided solely by the teachings 

 of Liebig, have come to view with chagrin 

 the billions of dollars of food that the Ameri- 

 can nation has exchanged for gold in the last 

 century, and figure it as so much potential 

 fertility wasted. For gold, exchanged for 

 nitrogen, potash and phosphorus, in the shape 

 of grain and meats, has no nutrient value as 

 food. 



Thus Malthus is born again, and, with the 

 passing of free land, the United States has 

 found itself confronted by a cry of exhaustion 

 of the soil. The theory is, in short: 



The acreage, the floor space for food con- 

 sumption, is definite. 



The plant food, the innate fertility of the 

 soil, is limited. 



The three elements, nitrogen, potash and 

 phosphorus, available as commercial fertilizers, 

 have been blocked out by geological surveys. 



