212 Agricultural Bacteriology. 



weather, but they never fire fang. This difference is 

 primarily due to the physical condition of the manure 

 and to its water content. The horse manure is dry and 

 open, allowing the air to penetrate into the pile, while 

 cow manure, even when large amounts of bedding are 

 used, is of such a physical texture that air cannot enter. 

 The large amount of air in the horse manure permits the 

 growth of aerobic bacteria and molds. The heat evolved 

 by their respiration is great and the decomposition they 

 produce very complete. The organic matter is practi- 

 cally burned, the carbon, hydrogen, and nitrogen pass- 

 ing into the air. Where decomposition occurs under an- 

 aerobic conditions the process is much slower and less 

 complete. If a pile of horse manure is well packed, so 

 as to exclude the air, the usual aerobic fermentation will 

 not occur, but will be supplanted by anaerobic action. 

 In such a case the loss of nitrogen and organic matter 

 will be much less. 



In handling any manure, the activity of aerobic organ- 

 isms should be excluded as far as possible by piling the 

 manure in large compact piles of considerable depth. If 

 the man are is allowed to accumulate in the stalls or feed- 

 ing sheds in which the animals run loose, the loss will be 

 reduced to the minimum, since the constant tramping of 

 the animals excludes the air, and the manure is protected 

 from leaching. 



If the manure is hauled directly to the field from the 

 stall the decomposition goes on to some extent on the sur- 

 face, but the soluble products formed pass into the soil. 

 There may be some loss of nitrogen as ammonia, but it is 

 certain that the losses are much smaller than when the 

 manure is allowed to rot in piles. If it is not possible to 

 apply it directly, the piles should be thoroughly packed 



