THE PRESERVATION OF MANURE 147 



March 29. Sept. 30. Loss. 



Lbs. L>bs. Per cent. 



Gross weight 226 222 



Nitrogen 1.04 i.oi 3.2 



Phosphoric acid 0.61 0.58 4.7 



Potash 1.20 0.43 35.0 



Value per ton $2.38 $2.16 



1 84. Losses by Fermentation. When rapid fer- 

 mentation takes place in manure, appreciable losses of 

 nitrogen may occur. When the manure is well com- 

 pacted and the pile is so constructed as to prevent the 

 rapid circulation of air through it, losses are reduced 

 to the minimum. Experiments have shown that 

 when leaching is prevented, the loss of nitrogen by 

 fermentation of the mixed manure is very small. 

 Under poor conditions losses by fermentation may 

 exceed 15 per cent. Hen manure, sheep man- 

 ure and horse manure suffer the greatest losses by 

 rapid fermentation. When extreme conditions, as ex- 

 cessive moisture, drought and high temperature, fol- 

 low each other, then the greatest losses occur. 



185. Different Kinds of Fermentation. The large 

 number of organisms present in manure all belong to 

 one of two classes : (i) aerobic, or (2) anaerobic. The 

 aerobic ferments require an abundant supply of 

 air in order to carry on their work. When deprived 

 of oxygen they become inactive. The anaerobic fer- 

 ments require the opposite condition. They become 

 inactive in the presence of oxygen and can thrive only 

 when air is excluded.- In the center of a well-con- 

 structed manure pile anaerobic fermentation takes 

 place while on the surface aerobic fermentation is act- 



