Calcium Cyanamide


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calcium cyanamide

[′kal·sē·əm sī′an·ə‚mīd]
(inorganic chemistry)
CaCN2In pure form, colorless rhombohedral crystals, the commercial form being a gray material containing 55-70% CaCN2; used as a fertilizer, weed killer, and defoliant.

Calcium Cyanamide

 

CaCN2, the calcium salt of cyanamide (H2N—C≡N, the amide of cyanic acid). Calcium cyanam-ide is a colorless crystalline compound that is soluble in water. It has a melting point of ~1300°C.

Technical-grade calcium cyanamide, which is produced by heating calcium carbide in a stream of nitrogen at 1000°C, is a dark gray powder consisting mainly of calcium cyanamide and carbon; the calcium cyanamide content is 57–60 percent. At 1400°–1500°C, technical-grade calcium cyanamide combines with sodium chloride (NaCl) to form cyanide flux, which in the recent past was the major source of hydrocyanic acid and cyanide salts. The salt sodium cyanide was formed by the reaction 2CaCN2 + 2C + 2NaCl ⇄ CaCl2 + Ca(CN)2 + 2NaCN. For a long time calcium cyanamide was used as a raw material in the production of melamine. Calcium cyanamide is toxic.

Calcium cyanamide is a nitrogenous fertilizer, a defoliant, and a herbicide. Fertilizer-grade calcium cyanamide, which has a nitrogen content of 18–22 percent, is effective in acidic and slightly basic soils when applied during autumn plowing. Calcium cyanamide is not used as a fertilizer in the USSR. It is used for the preharvest removal of leaves from cotton plants and for the elimination of shoots of orache, chickweed, daisies, shepherd’s purse, and other weeds from fields planted with grains and certain vegetables.

References in periodicals archive ?
The quicklime treatment was the most conducive to the growth of microbes with sugar, amino acids, amine, carboxylic acids and copolymers as substrates; the rhizospheric soil in the calcium cyanamide treatment was most conducive to the growth of microbes with copolymers, amino acids, amine and carboxylic acids as substrates and the rhizospheric soil in the CK treatment was the most conducive to the growth of microbes with phenolic acids as the substrate.
Of these, 2 types of carbon sources (D-galacturonic acid and a-D-lactose) were positively correlated with the principal component and soil microbes showed the most efficient utilisation of these carbon sources under calcium cyanamide treatment; the other 3 carbon sources (a-cyclodextrin, 2-hydroxy benzoic acid and L- asparagine) were negatively correlated with the principal component and soil microbes showed the most efficient utilisation of a-cyclodextrin and 2-hydroxy benzoic acid in the CK treatment (Table 5).
Under the four types of restoration techniques, 9 of the 14 carbon sources that played a major role were significantly positively correlated with the three principal components, including 7 types of carbon sources from the quicklime treatment and 2 types from the calcium cyanamide treatment; the remaining 5 carbon sources, which were mainly from CK, were significantly negatively correlated with the principal components.
The results showed calcium cyanamide and quicklime treatment resulted in a significant increase in these indices (e.
The highest enzymatic activity of cellulase and polyphenol oxidase was measured in the calcium cyanamide treatment and the polyphenol oxidase activity was higher under the quicklime treatment than under the calcium cyanamide or CK treatment.
In this study, the quicklime and calcium cyanamide treatments increased the microbial population and activity in tobacco rhizospheric soil.
However, the application of quicklime, calcium cyanamide and microbial agents were detrimental to the growth of these microbes, indicating that these treatments can reduce the content of phenolic compounds in the soil, which could alleviate the problems associated with consecutive tobacco monoculture.
In conclusion, the quicklime and, to a lesser extent, the calcium cyanamide treatment improved the tobacco rhizospheric microbial population and diversity.
The application of quicklime (900 kg/hm2) and calcium cyanamide (375 kg/hm2) to 6-year continuously cropped tobacco soil can improve the microbial population and microbial functional diversity.