504 SOILS: FB0FEBTIE8 AND MANAGEMENT 



The acid calcium cyanamide quickly loses its calcium, 

 leaving free cyanamide. Investigators differ as to the 

 process involved in this change, but the ultimate condi- 

 tion of the calcium is carbonate. The three explanations 

 of the process may be represented by the following re- 

 actions : — 



1. (CN . NH)2Ca + CO2 = 2 CN . NH2 + CaCO^, 



In this reaction the carbon dioxide of the soil water is 

 supposed to cause precipitation of the calcium. 



2. (CN . NH)2Ca + 2 H2O = 2 CN . NH2 + Ca(0H)2 



In this case hydrolysis occasions the reaction. The 

 hydroxide would, of course, be converted into carbonate 

 in the soil. 



3. (CN . NH)2Ca + CO2 = CN . NH2 + CaCNsCOs 



acid calcium carbon free calcium 



cyanamide dioxide cyanamide cyanamide 



carbonate 



CaCNaCOa + H2O = CN . NH2 + CaCOs 



free calcium 



cyanamide carbonate 



By this reaction calcium cyanamide carbonate is an in- 

 termediate product, but is at once hydrolyzed and free 

 cyanamide produced. 



The next step in the process is the formation of urea by 

 hydrolysis of the free cyanamide : — 



CN . NH2 + H2O = CO(NH2)2 



free cyanamide water urea 



The changes up to the production of urea are independent 

 of bacterial action. The urea is converted through bac- 

 terial action into ammonium carbonate : — 



