Urea phosphate is a fertilizer having NPK formula 17-44-0. It is soluble in water, and produces a strongly acidic solution. Urea phosphate is sometimes added to blends which contain calcium nitrate, magnesium nitrate and potassium nitrate to produce water-soluble formulas such as 15-5-15 and 13-2-20. The acidity of urea phosphate allows Ca, Mg and P to co-exist in solution. Under less acidic conditions, there would be precipitation of Ca-Mg phosphates. Urea phosphate is often used in drip irrigation to clean pipe systems.