In contrast to the unstable nature of the triammonium salts, the diammonium phosphate (NH4)2HPO4 and monoammonium salt (NH4)H2PO4 are stable materials that are commonly used as fertilizers to provide plants with fixed nitrogen and phosphorus.
[3] Ammonium phosphate is the main ingredient in pink fire retardant.
[4] Triammonium phosphate can be prepared in the laboratory by treating 85% phosphoric acid with 30% ammonia solution:[citation needed] (NH4)3PO4 is a colorless, crystalline solid.
The solid, which has the odor of ammonia, is readily soluble in water.
The salt converts to diammonium hydrogen phosphate (NH4)2HPO4.