Use in Agriculture:

Growers apply ammonium sulphate primarily where they need supplemental N and S to meet the nutritional requirement of growing plants. Since ammonium sulphate contains only 21 percent N, other fertilizer sources more concentrated and economical to handle and transport often make a better choice for N-deficient fields. However, it provides an excellent source of S, which supports or drives numerous essential plant functions, including protein synthesis.

Because the N fraction is present in the ammonium form of ammonium sulphate, rice farmers frequently apply it to flooded soils, since nitrate-based fertilizers are a poor choice due to DE nitrification losses.

A solution containing dissolved ammonium sulphate is often added to post-emergence herbicide sprays to improve their effectiveness at weed control. This practice of increasing herbicide efficacy with ammonium sulphate works particularly well when the water supply contains significant concentrations of calcium (Ca), magnesium (Mg) or sodium (Na). A high-purity grade of ammonium sulphate often works best for this purpose to avoid plugging spray nozzles.