Ammonium sulfate is used largely as an artificial fertilizer for alkaline soils.

1) In the soil, the sulfate ion is released and forms , lowering the balance of the (as do other sulfate compounds such as aluminum sulfate), while contributing essential for plant growth.

2) In addition, it is used as an agricultural spray adjuvant for water soluble insecticides, , and fungicides.

3) There it functions to bind iron and calcium cations that are present in both well water and plant cells. It is particularly effective as an adjuvant for 2,4-D (amine), glyphosate, and glufosinate herbicides.

4) It is also used in the preparation of other ammonium salts.

5) Ammonium sulfate precipitation is a common method for purifying by precipitation. As such, ammonium sulfate is also listed as an ingredient in many vaccines used in the , according to the Centers for Disease Control and Prevention (CDC).

6) Ammonium sulfate is also a food additive.