Potassium dihydrogen phosphate is a potassium salt in which dihydrogen phosphate(1-) is the counterion. It is a potassium salt and an inorganic phosphate. Monopotassium phosphate, MKP, (also potassium dihydrogenphosphate, KDP, or monobasic potassium phosphate), KH2PO4, is a soluble salt of potassium and the dihydrogen phosphate ion. It is a source of phosphorus and potassium as well as a buffering agent. It can be used in fertilizer mixtures to reduce escape of ammonia by keeping pH low.