FAEM MANURE 511 



pounds. Carbon dioxide is given off continuously during the 

 process. Some gaseous nitrogen as well as ammonia is prob- 

 ably lost because of the rapid alternations of conditions.^ 



289. Effect of decomposition on the value of manure. — 

 Because of the great loss of carbon dioxide and water dur- 

 ing the decay processes, there is considerable change in bulk 

 of the manure. Fresh excrement loses from 20 to 40 per cent, 

 in bulk by partial rotting and 50 per cent, by becoming more 

 thoroughly decomposed. This means that 1000 pounds of 

 fresh manure may be reduced to 800, 600, or 500 pounds, 

 according to the degree of change it has undergone. 



It is often argued that if the manure is properly stored, 

 this rapid loss of carbon dioxide and water will raise the 

 percentage amounts of the fertilizer elements. The simplify- 

 ing action of the anaerobic fermentation and putrefaction 

 is an additional reason for expecting better results from well- 

 rotted manure when it is compared, ton for ton, with the 

 fresh material. In practice, however, the losses in handling 

 due to leaching and fermentation are so dominant as to place 

 well-rotted manure at a disadvantage except on sandy land or 

 for garden and trucking purposes. At the Ohio Experiment 

 Station,^ yard and stall manure were compared in equal 

 amounts in a three-year rotation of maize, oats, and hay. The 

 yard manure was exposed for some months in the open, while 

 the stall manure came directly from the stable. The increase 

 due to yard manure is taken as 100 in each case. (Table CIX, 

 p. 512.) 



A change of a biological nature which sometimes takes 

 place in loose and rather dry manu.re is fire-fanging. Many 

 farmers consider this to be due to actual combustion, as the 



^UiKier the alternating aerobic and anaerobic conditions found in the 

 average maniare pile, gaseous nitrogen seems to be lost in considerable 

 amounts. This loss probably occurs through the oxidation of ammonia 

 to nitrites or nitrates with a later reduction of the nitrogen so carried 

 to a free state. 



^ Thome, C. E., The Maintenance of Fertility; Ohio Agr. Exp. Sta., 

 Bui. 183, p. 209, 1907. 



