SOIL AND SUBSOIL. 139 



HUMUS AND NITROGEN-CONTENT OF RUSSIAN RIVER SOIL. 



Influence of the Original Materials on the composition of 

 Humus. The great variability of the composition of humus 

 formed from different substances is well shown in the sub- 

 joined table, representing the results of experiments made by 

 Snyder, 1 who caused various substances to humify by mixing 

 the pulverized material intimately with a soil poor in humus, 

 and allowing the process to continue for a year. At the end 

 of that time the humus formed was extracted by the method 

 of Grandeau, outlined above, and analyzed, with the following 

 results. 



While it may be questioned whether the process of humifica- 

 tion had in these materials really reached the point of sensible 

 completion in all cases (notably in those of sawdust and cow 



1 Bull. No. 5 "5, Minn. Kxp't Station, p. 12, Chem. of Soils and Fertilizers, p. 94. 



2 The figures for cow manure are so far out of range with any cithers thus far 

 observed, that it seems reasonable to suppose that they are influenced by un- 

 changed substances present in the excreta. 



