Monopotassium phosphate, MKP, (also potassium dihydrogen phosphate, KDP, or monobasic potassium phosphate), KH₂PO₄, is a soluble salt of potassium and the dihydrogen phosphate ion which is used as a fertilizer, a food additive and a fungicide. It is a source of phosphorus and potassium. It is also a buffering agent. When used in fertilizer mixtures with urea and ammonium phosphates, it minimizes escape of ammonia by keeping the pH at a relatively low level.