Bone ash can be used alone as an organic fertilizer or it can be treated with sulfuric acid to form a "single superphosphate" fertilizer which is more water soluble:
:Ca(PO) + 2 HSO + 5 HO → 2 CaSO·2HO + Ca(HPO)·HO
Similarly, phosphoric acid can be used to form triple superphosphate, a more concentrated phosphorus fertilizer which excludes the gypsum content found in single superphosphate:
:Ca(PO) + 4 HPO → 3 Ca(HPO)