triple superphosphate TSP A fertilizer that is obtained by acid chemical attack of a phosphate rock with phosphoric acid. It contains around 46% P2O5 A product made from phosphate rock and phosphoric acid, usually containing 19 to 21% P (44 to 48% P2O5), and composed of monocalcium phosphate monohydrate, Ca(H2PO4)2 . 2H2O. calcium dihydrogen phosphate monocalcium phosphate concentrated superphosphate treble superphosphate phosphorus fertilizer