Lime nitrogen is a mixture of calcium cyanamide, calcium oxide and other insoluble impurities, which is gray-black in color and has a special odor. It is an alkaline fertilizer and one of the main raw materials of high-efficiency and low-toxicity carbendazim pesticide, which can be used as herbicide, fungicide, insecticide, etc.; additionally, it can be applied to manufacture cyanide melt and cyanide to make dicyandiamide, melamine and thiourea. Lime nitrogen is an important organic chemical material, which can be utilized as a metal heat treatment agent as well as for the elimination of schistosomes.

Lime nitrogen, also known as calcium cyanamide and black fertilizer, is a dark-gray oily particles with the chemical formula CaCN₂, which contains about 20% nitrogen. Lime nitrogen gets its name from the lime component it contains. It is a soil purifier that can be utilized both medicine and fertilizer, and has the dual role of soil disinfection and fertilization.