FtB 



6 





Issued January IT, WIS 



U. S. DEPARTMENT OF AGRICULTURE, 



BUREAU OF SOILS CIRCULAR No. 74. 



MILTON WHITNEY, Chief of Bureau. 



THE ORGANIC CONSTITUENTS OF SOILS. 



BY 



OSWALD SCHRETNER, 



Scientist in Charge, Soil Fertility Investigations. 



WASHINGTON: 



GOVERNMENT PRINTING OFFICE. 

 1913 



