MAP - Monoammonium phosphate

Application:

Agricultural use

MAP has been an important granular fertilizer for many years. It’s water-soluble and dissolves rapidly in adequately moist soil. Upon dissolution, the two basic components of the fertilizer separate again to release ammonium (NH₄⁺) and phosphate (H₂PO₄^-), both of which plants rely on for healthy, sustained growth. The pH of the solution surrounding the granule is moderately acidic, making MAP an especially desirable fertilizer in neutral- and high-pH soils. Agronomic studies show that, under most conditions, no significant difference exists in P nutrition between various commercial P fertilizers under most conditions.

Growers apply granular MAP in concentrated bands beneath the soil surface in proximity of growing roots or in surface bands. It’s also commonly applied by spreading it across the field and mixing it into the surface soil via tillage. In powdered form, it’s an important component of suspension fertilizers. When MAP is made with especially pure H₃PO₄, it readily dissolves into a clear solution dispersed as a foliar spray or added to irrigation water. The P₂O₅ equivalent content of high-purity MAP is usually 61 percent.

Non-agricultural uses

MAP is used in dry chemical fire extinguishers commonly found in offices, schools and homes. The extinguisher spray disperses finely powdered MAP, which coats the fuel and rapidly smothers the flame.