COMMERCIAL FERTILIZERS 503 



factured in this country has about the following composi- 



tion:1 — Percent 



Calcium cyanamide .... CaCN 2 45.92 



Calcium carbonate .... CaC0 3 4.04 



Calcium sulfide CaS 1.73 



Calcium phosphide .... Ca 3 P 2 0.04 



Calcium hydroxide .... Ca(OH) 2 26.60 



Free carbon C 13.14 



Iron and alumina R2O3 1.98 



Silica Si0 2 1.62 



Magnesia ....... MgO 0.15 



Combined moisture .... 3.12 



Free moisture H 2 0.35 



Undetermined 1.31 



100.00 



According to this composition the material would con- 

 tain 16 per cent of nitrogen. Lime in the forms of carbo- 

 nate and hydroxide would add somewhat to its value, 

 and the residue of the calcium cyanamide, which upon 

 decomposition is also calcium hydroxide, is likewise ben- 

 eficial to the soil. 



425. Changes of calcium cyanamide in the soil. — 

 Calcium cyanamide must be decomposed in the soil be- 

 fore its nitrogen becomes available to plants. There 

 are several steps in the decomposition process by which 

 the nitrogen finally emerges in the form of ammonia. 

 These, according to Pranke in the work just cited, con- 

 sist first of hydrolysis, by which acid calcium cyanamide 

 and calcium hydroxide are formed : — 



2 CN . NCa + 2 H 2 = (CN . NH) 2 Ca + Ca(OH) 2 



calcium water acid calcium calcium 



cyanamide cyanamide hydroxide 



1 Pranke, E. J. Cyanamid, p. 8. Eastern, Pennsylvania. 1913. 



