316 Manures, Composts, Green Manures 



Formula 1 



AiuLuonium sulfate 67.5 pounds 



Acid phosphate 22 . 5 



Ground limestone 60 



Use 150 pounds of this mixture per ton 

 of straw. 



Other sources of nitrogen may be employed, such as urea, calcium 

 cyanamide, or ammonium phosphate. The amounts of phosphate 



1 *1S:~^J»*^ Jf*;^ 



Fig. 126. Effect of temperature upon composting: 1, 7°C; 2, 7°C; 3, 18°C; 4, 



27°C; 5, 37°C. All except 1 received supplementary additions of nitrogen and 



mineral salts (from Waksman and Gerretsen). 



and lime added are adjusted according to the nature of the nitrogen 

 source used. 



When the moisture content of a heap of plant residues is not high 

 enough to allow normal decomposition and is not low enough to 

 prevent it, a phenomenon known as self-heating may occur. Animal 

 manures as well as plant residues, especially hay, kept in heaps, may 

 undergo limited decomposition; this may lead to the formation of 

 certain volatile substances, which, on coming in contact with the 

 air, ignite spontaneously. This is also true of heaps of peat. The 

 heap acts as an insulator, preventing radiation of heat from the inside 

 and penetration of oxygen from the outside. The lack of sufficient 



