92 SOILS AND FERTILIZERS 



Humic acid -f- calcium carbonate = calcium humate -f- C0. 2 . 

 Humic acid + potassium sulphate = potassium humate, etc. 



The fact that a union occurs between the organic 

 matter and the soil has been demonstrated by mixing 

 with soils known amounts of. various organic materials, 

 as cow manure, green clover, meat scraps, and saw- 

 dust, and allowing liumification to go on for a year or 

 more. After liumification has taken place, the humus 

 extracted from the soil contains more potash, phos- 

 phoric acid, and other elements than were present in 

 the humus of the original soil and humus-forming 

 material, showing that a chemical union has taken 

 place between the decaying organic matter and the soil. 

 The power of various organic substances to produce 

 humates is illustrated in the following table : 29 



Humic phos- Humic 



phoric acid. potash. 



LOW manure humus : Grams. Grams. 



In original manure and soil 1.17 1.06 



In final humus product (after liu- 

 mification) 1.62 1.27 



Gain in humic forms 0.45 0.21 



Green clover humus : 



In original soil and clover 3.21 5.26 



In final humus product 3.74 4.93 



Gain in humic forms 0.53 (Loss) 0.33 



Meat scrap humus : 



In original meat scraps and soil- • 1.07 0.25 



In final humus product 1.1S 0.36 



Gain o. 1 1 o. 1 1 



