THEORIES CONCERNING SOIL FERTILITY 321 



of which the President soon afterward withdrew from entry the re- 

 maining government lands that were known to contain phosphate 

 deposits, acting upon the advice of the United States Geological 

 Survey and the National Conservation Commission; while on 

 December 10, 1908, the daily press of the country very generally 

 published a Washington dispatch headed " SOIL WON'T WEAR 

 OUT," in which Professor Whitney was credited with the following 

 statements : 



"There is a general impression among economists that soil fertility is declin- 

 ing through loss of mineral plant food, but the Bureau of Soils, through the 

 extensive soil surveys and investigations made in the laboratories and from the 

 study of world-wide records, has determined that this impression of the decline 

 of soil fertility is erroneous. 



"It is not unreasonable to expect that as this country becomes more thickly 

 settled and our people are forced to cultivate smaller areas, with more intelli- 

 gent and more intensive methods, the actual amount of crops obtained from 

 the land now in crops can be increased two and one half times over what we 

 are now producing. 



"But the amount of land in crops is only about one fourth of the amount in 

 farms. Applying this ratio to the whole amount in farms, it is apparent that, 

 the land in farms at present can be expected to produce in time something like 

 ten or twelve times the amount of crops that are now produced on these farms. 



"So far as the present outlook is concerned, the nation possesses ample 

 resources in its soils for any conceivable increase in population for several 

 centuries. 



"The Bureau of Soils finds that the decline in yield is due generally to the 

 accumulation of organic products in the soil which are not eliminated through 

 proper cultural methods as fast as they have accumulated, and that the failures 

 that are reported are, therefore, due to improper methods of cultivation and 

 crop rotation. 



"Our own government statistics show that during the last forty years the 

 yields per acre of all our cereal crops have shown a tendency to increase. Statis- 

 tics of all the European countries show that the yields in recent years have con- 

 sistently increased." 



Of course this press dispatch would not be quoted here except 

 that it is in strict accord with the persistent teaching of Whitney 

 and Cameron, which will be found of greatest interest for compari- 

 son with that of Jethro Tull or Doctor Hunter, and with Liebig's 

 nitrogen theory. 



Since the above was written, Bulletin 55 of the Bureau of Soils, 

 " Soils of the United States," by Milton Whitney, has been pub- 



