798 



PRINCIPLES OF SOIL MICROBIOLOGY 



increase in the nitrifying power of a semi arid soil, upon which legumes 

 have previously grown; it was suggested that a growing crop may have 

 a different influence upon nitrate formation in different soils. 120 



TABLE 94 

 Effect of the second crop of wheal and of soybeans upon the oxidation processes in 



sand cultures 



* Including also the soil grains which adhered to roots. 



The growing crop may have a depressive effect upon the nitrate 

 content of the soil (not necessarily nitrate-producing capacity of the 



120 Kellerman, K. F., and Wright, R. C. Mutual influence of certain crops in 

 relation to nitrogen. Jour. Amer. Soc. Agr., 6: 204-210. 1914. 



