Ammonium nitrate is a chemical compound with the chemical formula NH4NO3. It is a white crystalline solid. It is highly soluble in water and hygroscopic as a solid, although it does not form hydrates. It is predominantly used in agriculture as a high-nitrogen fertilizer. Ammonium nitrate is an important fertilizer with NPK rating 34-0-0 (34% nitrogen). Its other major use is as a component of explosive mixtures used in mining, quarrying, and civil construction.