Usage - agriculture. Chemical formula - (NH4)2HP04. Form - granules. Colour - brown / dark brown. Diammonium phosphate is a highly concentrated granular complex nitrogen-phosphorus fertilizer. Produced by neutralizing phosphoric acid with ammonia. Diammonium phosphate is a highly effective fertilizer used on all types of soils for the main and pre-sowing application for all crops. The product is used in spring or for plowing the soil, as well as for top dressing during the growing season.