THEORY OF SOIL FERTILITY 197 



examined and compared with the older soils 

 of Europe. The suspicion that our soils were 

 breaking down after two or three generations 

 of cropping, and that the European soils were 

 increasing in productiveness after a thousand 

 years of cropping, was a popular superstition. 

 Surely, if the capacity of the soil is so simple 

 a thing that it can be reduced to fractions, an 

 examination of the older soils of Europe would 

 reveal that fact. 



Accordingly, thousands of samples of farm 

 soils were secured from Europe and subjected 

 to analysis. The result is found entire, in 

 Bulletin 57, Bureau of Soils, for any reader 

 who cares to pursue this element of the sub- 

 ject. 



A result rather startling to those who believe 

 in the book-keeping theory of soil fertility was 

 forced upon the investigators. In mineral 

 content (which was the only problem to be 

 solved) they found no appreciable difference 

 between the older soils of Europe and our own. 



Commenting on the results of the researches, 

 Director Milton Whitney said: 



"Two points will be mentioned to show the 

 futility of the bookkeeping system of estimat- 

 ing the future resources of the soil. 



