Potassium phosphate is used as a medicine, food additive and fertilizer. As a medicine, potassium phosphate provides phosphates in a form usable by the human body. It is produced when phosphoric acid reacts with potassium carbonate.
When combined with urea and ammonium phosphate and used as a fertilizer, potassium phosphate works by lowering the pH of the soil, which then loses less ammonia. Potassium phosphate fertilizer is used in hydroponic gardens and greenhouses. It also has fungicidal properties; it inhibits unwanted fungal growth.
When used medically to treat a phosphate deficiency, potassium phosphate is administered intravenously. Because potassium phosphate can disrupt the body's calcium levels, patients must have their calcium and phosphorous levels measured before and during administration. The primary side-effect of potassium phosphate, aside from the preventable calcium imbalance, is a burning sensation at the injection site.
As a food additive, all forms of potassium phosphate are categorized under the additive number E340. Potassium phosphate is used as a stabilizer, as a desiccant and to increase antioxidant activity. Food-grade phosphate is vegan, kosher and halal, and it does not carry any warnings or side effects for consumers who do not suffer from calcium deficiency. People with calcium deficiencies should avoid potassium phosphate.