Ammonium sulfate [(NH₄)₂ SO₄] was one of the first and most widely used nitrogen (N) fertilizers for crop production. It’s now less common but especially valuable where both N and sulfur (S) are required. Its high solubility provides versatility for a number of agricultural applications.

Ammonium sulfate (sometimes abbreviated as AS or AMS) has been produced for more than 150 years. Initially, it was made from ammonia released during manufacturing coal gas (used to illuminate cities) or from coal coke used to produce steel.