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

Ammonium sulfate is commonly added to bread products as a dough conditioner. It is also a component in fire extinguisher powder and flame-proofing agents. It is used for many applications in the chemical, wood pulp, textile, and pharmaceutical industries.