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SOILS AND FERTILIZERS 



115. Comparative Value and Composition of Humates. 



The humus produced from a nitrogenous material, 

 as meat scraps, is more valuable than 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 humates. 

 There is also a great difference in soils as to their 

 humus-producing power. Soils deficient in lime or al- 

 kaline compounds possess only a feeble power to pro- 

 duce humates. There is too a marked variation in 

 the composition of the humus from different kinds of 

 organic matter. Straw, sawdust, and sugar, materials 

 rich in cellulose and other carbohydrates, yield a humus 

 characteristically 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 

 nitrogen and possessing the power to combine with the 

 potash and phosphoric acid of the soil to form humates. 



COMPOSITION OF HUMUS PRODUCED BY 



