Answer: superphosphates

AnswerCrossword Clue
superphosphatesSUPERPHOSPHATE, acid phosphate
superphosphatesmixture prepared with phosphoric acid and containing about 45 percent of soluble phosphates, used as a fertilizer
superphosphatesmixture of calcium acid phosphate and calcium sulfate prepared by treating phosphate rock with sulfuric acid: used chiefly as a fertilizer