364 



SOILS. 



ANALYSES OF BLACK SOILS, 



It will be seen that the Russian soil is of high fertility ac- 

 cording to the standards given above, and that the nitrogen- 

 content of the abundant humus is amply within the limits of 

 adequacy suggested by the experience in California and Ha- 

 waii. The humus-content of the arid California soils is char- 

 acteristically low as compared with the Russian tchernozem 

 as well as with the Houma back-land of humid Louisiana; 

 but its nitrogen-content is doubtless at least three times that of 

 the latter, as is that of the humus of similar lands in which 

 it has been determined. 



