u 



f. 



THEORIES CONCERNING SOIL FERTILITY 313 



Liebig so emphasized the importance of the mineral plant food, 

 as established by De Saussure's careful work, that it has ever since 

 been referred to as " Liebig's mineral theory of plant nutrition." 



In recent years, Whitney and Cameron have revived Decandolle's 

 theory of toxic excreta from plant roots, in support of another more 

 radical theory announced by them, to the effect that soils do not 

 wear out or become depleted by cultivation and cropping. While 

 this theory is advanced with no adequate foundation and in direct 

 opposition to practical experience and to so many known facts of 

 mathematics, chemistry, and geology, that it is in itself quite 

 unworthy of further consideration, the fact is that it has been pro- 

 mulgated by Professor Whitney as Chief of the United States 

 Bureau of Soils, and by Doctor Cameron, as the chief chemist of the 

 same Bureau; and, consequently, it cannot be ignored. 



The author finds practically no support for these radical theories, 

 either in the American Experiment Station bulletins or in the 

 publications from the older scientific bureaus at Washington, 

 such as the United States Geological Survey, the Bureau of Chem- 

 istry, and the Bureau of Plant Industry; while they are directly 

 contrary to the teachings of all recognized European authorities. 

 But even above any so-called authorities, we must recognize facts, 

 if there are any, for an opinion contrary to the facts is of no per- 

 manent value by whomsoever it may be held. 



The following statements from Whitney and Cameron will give 

 a clear idea of the plain teachings of the Bureau of Soils, so far as 

 represented by its leaders. 



Thus, on page 64 of Bulletin 22 of the Bureau of Soils, published 

 by Whitney and Cameron in 1903, we read: 



" That practically all soils contain sufficient plant food for good crop yields, 

 that this supply will be indefinitely maintained," jetc. d 



Again, on pages 21 and 22, Farmers' Bulletin 257, published in 

 1906, we have the following definite statements from Professor 

 Whjtney: 



a' There is another way in which the fertility of the soil can be maintained, 

 viz., by arranging a system of rotation and growing each year a crop that is not 

 injured by the excreta of the preceding crop; then when the time comes round 

 for the first crop to be planted again, the soil has had ample time to dispose of the 

 sewage resulting from the growth of the plant two or three years before. This, I 



