ntJ A'PT'PT? "VVT 



Mro-Ctilttire 



AN OLD-KEW THEOBY. 



The inoculation of soil, like many other lately exploited 

 theories, has no doubt been known for hundreds of years. 

 There are evidences that it was practiced in England at 

 least a century ago, and it is thought to be an old custom 

 among the Chinese. Some space was given to "soil inoc- 

 ulation" in a preceding chapter, attention there being 

 devoted to the simple methods of infecting soil with 

 bacteria. 



IMPORTANT BXSCOVERDES. 



Some twenty years ago a German scientist, Nobbe, 

 discovered that the small nodules found on the roots of 

 the leguminous plants contained bacteria that took nitro- 

 gen from the air and transferred it to the plant It had 

 been known that cultivated soils were rapidly losing their 

 original supply of nitrogen and there seemed no practi- 

 cable way of restoring it in sufficient quantity. Commer- 

 cial nitrogen costs fifteen cents per pound and the 

 expense of applying it to the land to equalize the loss 

 from an ordinary farm crop is almost equal to the value 

 of a crop. Hence, the discovery that the legumes were 

 nitrogen-gathering, by means of these bacteria, was 



