INFLUENCE OF STABLE MANURE 



211 



apparent that, in the transformation of the manures, the hemi- 

 celluloses and cellulose disappear most rapidly. The crude protein 

 increases in proportion to the rest of the materials, because of the 

 growth of microorganisms. The relative amount of Hgnin increases 

 as a result of its greater resistance to decomposition and as a result 



15 30 



Time (Days) 



Fig. 78. — Amount of carbon dioxide evolved from soils treated with organic 

 matter (after Potter and Snyder). 



of the microbial synthesis of materials included in the lignin com- 

 plex. Some of the Hgnin actually decomposes, but so slowly as 

 compared to the rest of the constituents that its relative abundance 

 is greatly increased. 



Decomposition of the sugars, hemicelluloses, and cellulose, 

 of the urea and proteins, and of the fats and lignin, represents a 

 definite series of changes brought about by microorganisms. On 



