FERTILIZERS 143 



under continuous cropping and ordinary cultivation, and this 

 yield can be increased by rotation of crops, and still more by 

 improved methods of cultivation. Fertilizing is also a factor 

 which generally increases the yield, whether utilized by itself, 

 or in conjunction with other factors. The use of commercial 

 fertilizers must, however, be accompanied by intensive methods 

 of cultivation in order to be profitable, and now and then the 

 returns seem to diminish with continued use. Mr. Whitney, 

 chief of the bureau of soils in the United States department of 

 agriculture, maintains that he never saw a case of soil exhaus- 

 tion which was probably due to the actual removal of plant 

 food. He considers the so-called worn-out soils of the United 

 States due to conditions which make the plant food unavailable, 

 and holds that the primary object of fertilizing is the adaptation 

 of soils to any desired crop or crops. Fertilizing can also be 

 practiced to force growth, even on rich soil. Texture and 

 drainage of soils can be improved, the ratio of soil constituents 

 balanced, and acidity neutralized. Attention is called to the 

 facts that "the soils of India, which tradition says have been 

 cultivated for 2,000 years, under primitive methods, without 

 artificial fertilizing, still give fair returns. In Egypt, lands 

 which have been cultivated since history began are as fertile as 

 ever. In Europe there are records of cultivation of soils for 

 500 years.' 71 



Tradition is not always scientific, however, and soil is not 

 greatly taxed by such primitive methods of culture as have ex- 

 isted in India for 2,000 years. The sediment which is de- 

 posited by the waters of the Nile at every annual overflow is 

 entirely adequate to maintain the fertility of the cultivated 

 lands of Egypt, while fertilizing, improved methods of culti- 

 vation, and crop rotation have greatly increased the yield of 

 European soils. On some of the fields in France 28 bushels of 

 wheat are raised per acre where 17 bushels were raised 50 

 years ago. The soil of France is more fertile today than it was 

 in the time of Cresar. The fertility of the soil in Germany has 

 increased proportionately. In England, land on which wheat 

 was grown continuously for 50 years without fertilization yield- 

 ed 12 to 13 bushels per acre, while adjacent plots to which fer- 

 tilizers were applied averaged about 30 bushels per acre. Mr. 

 1 Industrial Commission, 10: clxxxviii, cxcii. 



