90 SOILS AND FERTILIZERS 



potash and phosphoric acid of the soil to form hu- 

 mates. 



COMPOSITION OF HUMUS PRODUCED BY SO 



Cow Green Meat Wheat Oat Saw- 

 manure, clover, scraps, flour. straw. dust. Sugar 



Carbon 41.95 54.22 48.77 51.02 54.30 49.28 57.84 



Hydrogen 6.26 3.40 4.30 3.82 2.48 3.33 3.04 



Nitrogen 6.16 8.24 10.96 5.02 2.50 0.32 0.08 



45-63 34-14 35-97 40.14 40.72 47-7 39-4 



Total 100.00 100.00 100.00 100.00 100.00 IOD.OO 100.00 



Highest. Lowest. Difference. 



Carbon 57.84 41.95 15.89 



Hydrogen 6.26 2.48 3.78 



Nitrogen 10.96 0.08 10.88 



Oxygen 47.07 34.14 12.93 



Variations in composition are noticeable. The 

 humus produced from each material as green clover, 

 oat straw, or sawdust, is different from that produced 

 from any other material. The humus from green 

 clover is very complex in nature. It contains both 

 nitrogenous and non-nitrogenous compounds, and 

 each class has a different action in humification 

 processes, hence it follows that the humus from the 

 green clover must be a complex mixture of both 

 nitrogenous and non-nitrogenous bodies. 



The nature of the humus, whether nitrogenous or 

 non-nitrogenous, is important. Humus produced from 

 sawdust and humus from meat scraps may be taken 

 respectively as types of non-nitrogenous and nitroge- 

 nous humus. 



106. Value of Humates as Plant Food. Various 

 opinions have been held regarding the actual value, 

 as plant food, of this product from partially decayed 

 animal and vegetable matter. Humus was formerly 

 regarded as composed only of carbon, hydrogen, and 



