Calcium Cyanamide. 765 



CALCIUM CYANAMIDE. 



Its Agricultural Use as a Fertilizer. 



Uv ('has. v. Jukitz. M.A., F.I.C.. AoTicultiual Research Chemist. 



Of all the varieties of fertilizers, good, indifferent, and bad, that are 

 usually applied to the soil, there is no class more important, and, at 

 the same time, more costly, than what has been termed the nitrogen 

 group. The fertilizers belonging to this class have the property of 

 stimulating the active growth of the plant and promote the formation 

 of its leaf system. They increase the size and weight of the ears in 

 cereal crops, but in the case of fruit-bearing plants they cause loss of 

 fruit by producing abnormal development of leaf and woody stem if 

 applied with too great liberality. While, therefore, it is essential 

 to be discreet in the use of the fertilizers of this group, it will easily 

 be realized that they are of great practical value to the crop. TJn- 

 fortunately the advantages of a proper use of nitrogenous fertilizers 

 are often as little understood as the caution necessary to prevent a 

 misuse. This, however, applies not merely in the case of fertilizers 

 of the nitrogen group, but wherever fertilizing of any kind has to be 

 practised, and hence has arisen the oft-quoted precept regarding the 

 need of " manuring with brains." 



From the time that the value of nitrogen compounds as fertilizers 

 of the soil began to be realized, up to recent years, agricultural 

 chemists have been continuously keeping their thoughts on the vast 

 i|uantities of 



Nitrogen ix tjik An;, 



and striving for some means of securing portion of that nitrogen and 

 liringing it into the soil for the benefit of the crops. That this could 

 he done for very many years Avithout affecting the quantity of nitrogen 

 remaining in the air was evident, because as much as seven tons of 

 nitrogen rest on every square yard of the earth's surface, that is to 

 say, in the air over the TJnion of vSouth Africa alone, there is no less 

 than lOj million of million tons of nitrogen. 



For a long time there seemed to be no way of utilizing this 

 stupendous store of nitrogen, and then, almost unexpectedly, after 

 much patient research, one method after another was announced and 

 practically applied. Amongst these was the process based on the use 

 of calcium carbide, the substance which had become prominent because 

 of its power of producing acetylene gas by mere addition of water, and 

 so affording an easy and portable ilium inant for bicycles, motor cars, 

 etc. When calcium carbide is heated to near 1200° C, and nitrogen 

 is passed over it, chemical combination takes place, and cyanamide or, 

 moire properly speaking, calcium cyanamide, is produced. The 

 article, as commonly purchased, contains about 50 to 55 per cent, of 

 pure calcium cyanamide, and this is the article which has lately come 



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