Super phosphate

Phosphorus is an essential nutrient and therefore is a common component of agricultural fertilizers. Tricalcium phosphate Ca3(PO4)2, a major component of phosphate rock such as phosphorite,[1] apatite, and other phosphate minerals, is too insoluble to be an efficient fertilizer. Therefore it can be converted into the more soluble monocalcium phosphate, generally by the use of sulfuric acid H2SO4. The result is hydrated to turn the calcium sulfate into the dihydrate gypsum and sold as superphosphate of lime. Alternately phosphate rock may be treated with phosphoric acid to produce a purer form of monocalcium phosphate and is sold as triple phosphate.