VALUE AND COMPOSITION OF HUMATES 89 



Humic phos- Humic 



phoric acid. potash. 



Meat scrap humUS : Grams. Grams. 



In original meat scraps and soil- 1.07 0.25 



In final humus product 1.18 0.36 



Gain o.n o.n 



Sawdust humus : 



In original sawdust and soil 0.85 0.67 



In final humus product 0.78 0.70 



Oat straw humus : 



In original straw and soil 1.02 2.42 



In final humus product 1.03 2.41 



105. Comparative Value and Composition of Hu- 

 mates. The humus produced from nitrogenous 

 bodies as meat scraps, is more valuable than that pro- 

 duced from cellulose bodies, as sawdust, because the 

 former has greater power of combining with the 

 phosphoric acid and potash of the soil. The non- 

 nitrogenous compounds, as cellulose, starch, and sugar, 

 undergo fermentation but seem to possess little, if any, 

 power to form tuimates. There is also a great differ- 

 ence in soils as to their humus-producing powers. 

 Soils deficient in lime or alkaline compounds possess 

 only a feeble power to produce humates. There is 

 also a marked variation in the composition of the 

 humus produced from different kinds of organic matter. 

 Straw, sawdust, and sugar, materials rich in cellulose 

 and other carbo-hydrates, yield a humus characteris- 

 tically rich in carbon and poor in nitrogen. Materials 

 rich in nitrogen, like meat scraps, green clover, and 

 manure, produce a more valuable humus, rich in nitro- 

 gen and possessing the power to combine with the 



