Diammonium Phosphate 18:46:00

Diammonium Phosphate Fertilizer is the world’s most widely used phosphorus (P) fertilizer. It is made from two common constituents in the fertilizer industry and it is popular because of its relatively high nutrient content and its excellent physical properties.

DAP fertilizer is an excellent source of phosphorus (P) and nitrogen (N) for plant nutrition. It is highly soluble and thus dissolves quickly in soil to release plant-available phosphate and ammonium. A notable property of DAP is the alkaline pH that develops around the dissolving granule. As ammonium is released from dissolving DAP granules, volatile ammonia can be harmful to seedlings and plant roots in immediate proximity. This potential damage is more common when the soil pH is greater than 7, a condition that commonly exists around the dissolving DAP granule. To prevent the possibility of seedling damage, care should be taken to avoid placing high concentrations of DAP near germinating seeds. The ammonium present in DAP is an excellent N source and will be gradually converted to nitrate by soil bacteria, resulting in a subsequent drop in pH. Therefore, the rise in soil pH surrounding DAP granules is a temporary effect. This initial rise in soil pH neighboring DAP can influence the micro-site reactions of phosphate and soil organic matter.

Product Properties
Chemical Formula(NH4)2HPO4
Composition18% N 46% P2O5 (20% P)
Solution pH7.5 to 8
Molar Mass 132.06 g/mol
Appearance White powder
Density1.619 g/cm3
Melting point155 °C (311 °F; 428 K) decomposes
Solubility in water57.5 g/100 mL (10 °C) 106.7 g/100 mL (100 °C)
SolubilityInsoluble in alcohol, acetone and liquid ammonia


Technical Specification
Moisture by weight>2.5
Total nitrogen18<
Ammonical nitrogen 15.5<
Total nitrogen in the form of urea >2.5
Neutral ammonium citrate soluble phosphates as P205 46.0 <
Water soluble phosphate as P20541.0<
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