Monopotassium Phosphate, MKP, (also potassium dihydrogenphosphate, KDP, or monobasic potassium phosphate), KH2PO4, is a soluble salt of potassium and dihydrogen phosphate ions used as fertilizers, food additives and fungicides. It is a source of phosphorus and potassium. It is also a buffering agent. When used in fertilizer mixes with urea and ammonium phosphate, it minimizes ammonia escape by keeping the pH at a relatively low level.