Shuanglian

Production

Ammonium sulfate, often abbreviated as AS or AMS, has a long production history spanning over 150 years. Initially, it was derived from ammonia released during coal gas manufacturing processes or from coal coke used in steel production.

In contemporary manufacturing, ammonium sulfate is synthesized by reacting sulfuric acid with heated ammonia. The reaction conditions are carefully managed to produce crystals of an optimal size. These particles are then screened and dried, and some are coated with a conditioner to minimize dust and caking.

Today, most of the demand for ammonium sulfate is met using byproducts from various industries. For instance, the production of nylon generates ammonium sulfate as a co-product, and some byproducts that contain ammonia or spent sulfuric acid are also converted into ammonium sulfate for agricultural use.

Ammonium sulfate typically ranges in color from white to beige and is sold as highly soluble crystals known for their excellent storage properties. The particle size is adjustable depending on its intended application.

Chemical Properties

• Chemical formula: (NH₄)2SO₄
• N content: 21%
• S content: 24%
• Water solubility: 750 g/L
• Solution pH: 5 to 6

Agricultural Use

Farmers often apply ammonium sulfate to provide essential nitrogen (N) and sulfur (S) for crop nutrition. Although it contains only 21% nitrogen, making it less concentrated than other fertilizers, it is an excellent source of sulfur which is vital for various plant functions, including protein synthesis.

Given its nitrogen content in ammonium form, ammonium sulfate is particularly beneficial for rice cultivation in flooded soils, where nitrate-based fertilizers are ineffective due to denitrification losses.

A solution of dissolved ammonium sulfate is frequently added to post-emergence herbicide sprays to enhance weed control effectiveness. This practice is especially useful when the water supply contains significant concentrations of calcium (Ca), magnesium (Mg), or sodium (Na). Using a high-purity grade can prevent spray nozzle clogging.

Management Practices

Once incorporated into the soil, ammonium sulfate quickly dissolves into its ammonium and sulfate components. If left on the soil surface, the ammonium may be subject to gaseous loss in alkaline conditions. In such cases, it is recommended to integrate the material into the soil promptly or apply it before irrigation or predicted rainfall.

Most plants can utilize both ammonium and nitrate forms of nitrogen for growth. In warm soils, microbial activity rapidly converts ammonium to nitrate through the process of nitrification [2 NH₄⁺ + 3O₂→ 2NO₃^- + 2H₂O + 4H⁺]. This reaction releases acidity (H⁺), eventually lowering the soil pH with repeated use.

The acidifying effect of ammonium sulfate on soil is due to the nitrification process rather than the presence of sulfate, which has a negligible impact on pH.

For more details on ammonium sulfate granular and the differences between prilled urea and granular urea, explore further.