calcium cyanamide

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun A white or colorless crystalline solid, CaCN₂, that is used as a fertilizer and weed killer and impairs ethanol metabolism in humans who are exposed to it. The presence of impurities can cause it to appear grayish-black.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun inorganic chemistry The compound CaCN2 produced by reacting calcium carbide with nitrogen; it is used as a fertilizer