Diammonium phosphate, commonly referred to as (DAP 18-46), is the world's most used phosphate fertilizer. As a primary nutrient, DAP helps the plant to capture and convert the sun's energy into useful compounds for the plant. It also stimulates root development and enhances the durability of the stems. Usage: In addition to its wide usage in the agricultural sector, DAP is also used to impregnate matches, and as a flame-retardant (for fighting forest fires).