IOO SOILS AND FERTILIZERS 



supplied. Swampy, peaty, and muck soils contain 

 large amounts ; in fact, they are often overstocked 

 with humus. 



107. Active and Inactive Humus. — When soil has 

 been under long cultivation, and no manures have 

 been used, the nitrogen and mineral matters combined 

 with the humus are reduced. The humus from long 

 cultivated fields contains a higher per cent, of carbon 

 than that from well-manured or new land ; it is also 

 less active because of the higher per cent, of carbon 

 which does not readily undergo oxidation. 17 



Humus from Humus from 



new soil. old soil. 



Per cent. Per cent 



Carbon 44-12 50.10 



Hydrogen 6.00 4.80 



Oxygen 35.16 33.70 



Nitrogen 8.12 6.50 



Ash 6.60 4.90 



Total humus material "5.30 3.38 



108. Influence of Different Methods of Farming 

 upon Humus. — The general system of farming has a 

 direct effect upon the humus content and composition 

 of the soil. Where live stock is kept, the manure 

 properly used, and the crops systematically rotated, 

 the crop-producing power of the land is not decreased, 

 as in the case of the one-crop system. The influence 

 of different systems of farming upon the humus con- 

 tent and other properties of the soil may be observed 

 from the following table : 3 ° 



