Volume IX APRIL, 1919 Part II 



DECOMPOSITION OF CYANAMIDE AND DICYANO- 

 DIAMIDE IN THE SOIL 



By G. a. COWIE, M.A., B.Sc, A.LC. 

 {Rolhuin.sted Experimenlal Skdion, Harpenden.) 



The present investigation was undertaken to study the decomposition 

 of cyanamide and dicyanodianiide in the soil and their specific action on 

 plant growth. Their close chemical relationship necessitated a com- 

 parison of their respective behaviour in the soil. Dicyanodiamide is a 

 polymer of cyanamide to which the formula CgH^N^ is assigned. Morrell 

 and Burgen(i) and Werner (2) have shown that the polymerisation is 

 caused by acids or alkalis, even in small amount, but a weak alkali is 

 substantially more effective than a correspondingly weak acid ; the rate 

 of the change is greatly increased by raising the temperature. The 

 process does not appear to be reversible. 



According to Werner cyanamide can be represented by either of the 

 formulae (1) CNNHj, (2) NH = C = NH. According as the equilibrium 

 assumed to exist between these tautomeric forms in a neutral solution 

 is displaced by an acid or base, so the polymerisation may give rise to 

 isomeric forms of dicyanodiamide, thus: 



.N. NH 



H„NCf iCNHjj HN = C< \c = NH 



\^^ \nh/ 



Hofmann's formula (3) Baumann's formula (4) 



In contrast to the closed-chain formulae, however, the following 

 open-chain structures have been proposed for dicyanodiamide : 

 /NH, /NH, /NHj 



c=nh" c=nh" c=n - c=n 



\nhcn \n = c=nh \NH2 



by Bamberger (5) Rathke(6) Pohl(i) 



The decomposability of dicyanodiamide in the soil may throw some 

 light upon its chemical structure; if it showed little tendency to form 

 ammonia under these conditions, it might be more probably an imino 

 than an amino grouping^. 



' Miyake (8) has shown that, fatty amino compounds are ammonified much more 



easily than aromatic compounds, while aromatic imino compounds are much more 

 difficultly ammonified than aromatic amino compounds. 



Joum. of Agric. Soi. ix 8 



