376 THE PRINCIPLES OF SOIL MANAGEMENT 



of their passing off from the heap into the air. The drier 

 the heap, the more apt these substances are to escape. 



The production of ammonia is very rapid from some 

 of the compounds in farm manure. Urea, in which form 

 the nitrogen of urine is largely found, undergoes con- 

 version into ammonia very rapidly, and some loss in 

 this way is inevitable even under the best management. 

 Chemically the process is a simple one, which may be 

 represented by the following equation: 



CON 2 H 4 + H 2 = 2 NH 3 + C0 2 . 

 2 NH 3 + CO, + H 2 = (NHJ, C0 3 . 



The use of certain preservatives makes it possible 

 to decrease the loss of ammonia from manure. The 

 preservatives are intended to convert the ammonia into 

 a less volatile compound. For this purpose gypsum, 

 kainit, superphosphates and ground phosphate rock are 

 used. The action of gypsum, for instance, in the manure, 

 is to convert ammonia or ammonium carbonate into 

 the form of ammonium sulfate, which is not volatile. 

 The reaction is as follows: 



(NH 4 ) 2 C0 3 + CaS0 4 - (NH 4 ) 2 S0 4 + CaC0 3 . 



It is customary to sprinkle the preservative in the 

 stall of the animal, where it comes in contact with the 

 excreta as soon as they are voided. Salts of calcium 

 other than the sulfate, cannot be used, on account of 

 their action in decomposing ammonium salts. 



The decomposition of proteins forming, among other 

 products, hydrogen sulphide, which becomes oxidized 

 to sulfuric acid, causes a part of the ammonia to natu- 



