2oz-8oz Mono Potassium Phosphate (MKP) 99% Pure Fertilizer, Buffering Agent 100% Satisfaction guaranteed!!! Free Shipping Monopotassium phosphate Monopotassium phosphate is the inorganic compound with the formula KH₂PO₄. Together with dipotassium phosphate it is often used as a fertilizer, food additive, and buffering agent. The salt often crystallizes with the dipotassium salt as well as with phosphoric acid. Single crystals are paraelectric at room temperature. At temperatures below −150 °C (−238 °F), they become ferroelectric.