Ammonium sulphate is widely used as a sulphur (S) fertilizer, constituting about 50% of global S use.Ammonium sulphate is mainly used for the supplemental need of N and S to meet the nutritional requirement of growing plants. It is an excellent source of S, which also has several essential functions in plants. It is largely used as an artificial fertiliser for alkaline soils. The sulphate ion forms sulphuric acid in the soil and lowers the pH balance of the soil.

The primary use of ammonium sulfate is as a fertilizer for alkaline soils. In the soil, the ammonium ion is released and forms a small amount of acid, lowering the pH balance of the soil, while contributing essential nitrogen for plant growth.

Ammonium sulfate (American English and international scientific usage; ammonium sulphate in British English); (NH4)2SO4, is an inorganic salt with a number of commercial uses. The most common use is as a soil fertilizer. It contains 21% nitrogen and 24% sulfur.