Fertilizer - Wikipedia
The large production of sulfuric acid is primarily motivated by this application. In the nitrophosphate process or Odda process (invented in 1927), phosphate rock with up to a 20% phosphorus (P) content is dissolved with nitric acid (HNO 3) to produce a mixture of phosphoric acid (H 3 PO 4) and calcium nitrate (Ca(NO 3) 2).