Ammonium Sulfate

About This Product

Ammonium sulfate has the formula (NH4)2SO4 and CAS number 7783-20-2, supplied as white to beige crystals or granules, freely soluble in water. Much of it is recovered as a co-product of caprolactam manufacture and of coke oven gas scrubbing rather than being made for its own sake. As a fertiliser it carries 21 percent nitrogen, lower than urea or ammonium nitrate, but it also delivers 24 percent sulphur, which has become agronomically important as atmospheric sulphur deposition has fallen with industrial emissions controls. Its acidifying effect is the property to understand. As soil bacteria nitrify the ammonium to nitrate they release hydrogen ions, and the sulfate anion remains behind, so the net effect lowers soil pH measurably over time. On calcareous and alkaline soils that is useful, improving the availability of phosphorus, iron, zinc and manganese, which lock up at high pH. On soils that are already acid it compounds the problem and requires liming. In biochemistry it is used quite differently, to precipitate proteins selectively by salting out. It is used in nitrogen and sulphur fertilisers, alkaline soil management, protein purification, fermentation media, flame retardants and as a herbicide adjuvant. Bio Green Chem supplies ammonium sulfate to specification on nitrogen and sulphur content, free acid, moisture, iron, insolubles and particle size.