THE FERMENTATIONS OF MANURE. 73 



loss. Some manure heats more rapidly than others, that from the 

 horse being especially subject to this destructive fermentation; a 

 fact due partly to the large amount of hay that it contains and partly 

 to its loose and porous nature, which allows a free access of air. It 

 suffers more loss for this reason than most other types of manure a 

 loss that may be lessened by mixing with it some of the moister, 

 denser cow manure. Liquid manure also is subject to heavy losses, 

 because it so rapidly undergoes the ammonical fermentation. 



There are two general methods of controling and reducing these 

 losses. The first is by chemical means. Since the ammonia is 

 volatile and a strong base, the addition to the manure of some 

 chemical to conbine with it will produce salts that will be more 

 likely to be retained in the manure. For this purpose quite a list 

 of substances has been recommended. Among them are, gypsum, 

 burned lime, shell lime, lime-stone, kainit, superphosphates and sul- 

 phuric acid. Each of these has a value when properly used, but 

 none of them will wholly prevent nitrogen loss and all are some- 

 what costly. The losses due to ammonia vaporization may be pre- 

 vented by these chemicals; but the losses caused by the liberation 

 of free nitrogen cannot be checked by any means short of stopping 

 bacterial growth, and this would check the beneficient as well as the 

 injurious fermentations. On the whole, the result of experience 

 seems at present to be against the use of chemical means of 

 preserving manure. 



The second method is mechanical and is more efficient. It is 

 based upon the facts already emphasized, viz., that the destructive 

 fermentations take place most vigorously in the presence of a large 

 supply of oxygen and that the volitilization is much more rapid 

 from a partly dry than from a wet mass. Hence manure that is 

 loosely piled loses much more nitrogen than that which is firmly 

 compacted. The practice of firmly compacting manure into conical 

 heaps with smooth sides is best calculated to reduce the losses to a 

 minimum. Experiment has shown that a lot of manure firmly 

 compacted may lose 15 per cent, of its nitrogen during storage, 

 while a similar lot loosely stored loses 35 per cent.; a very striking 

 testimony to the value of compacting. If, further, the manure be 

 7 



