MAP vs DAP: what is the difference?
VBT Global · Published
Short answer: MAP and DAP are both ammonium phosphates made from phosphoric acid and ammonia. MAP carries more phosphorus and less nitrogen and reacts acidic in soil. DAP carries more nitrogen and less phosphorus and reacts alkaline. MAP suits neutral to alkaline soils and situations close to the seed. DAP suits neutral to acidic soils, applied away from the seed.
Same family, different ratio
Both are made by reacting phosphoric acid with ammonia. With less ammonia you get monoammonium phosphate (MAP, NH₄H₂PO₄). With more ammonia you get diammonium phosphate (DAP, (NH₄)₂HPO₄). The extra ammonia is why DAP has more nitrogen and why it releases ammonia as it dissolves.
Nutrient content in Vietnam's regulation
Vietnam's fertilizer quality regulation QCVN 106:2025/BNNMT sets the minimums:
| Total N, min (% by mass) | Available P₂O₅, min (% by mass) | |
|---|---|---|
| MAP | 10 | 50 |
| DAP | 15 | 42 |
These are legal floors. Commercial grades are agreed per contract and shown on the certificate of analysis.
How they behave in soil
- MAP gives an acidic reaction around the dissolving granule. In alkaline or calcareous soils this helps keep phosphorus available to roots for longer.
- DAP gives a temporary alkaline reaction and releases some free ammonia. On acidic soils that is harmless or even helpful. But placed directly with the seed, the ammonia can damage germinating seedlings.
- Over a season both acidify the soil slightly, because the ammonium is converted to nitrate.
Which one to choose
- Alkaline or calcareous soils, or a starter fertilizer near the seed: MAP
- Neutral to acidic soils, broadcast or banded away from the seed, where extra nitrogen is welcome: DAP
- NPK blending: both work. Many blenders choose by the N:P ratio they need and by landed cost.
- Fertigation: use water-soluble crystalline MAP, not granular DAP
Trade details
| HS code | Usual packing | |
|---|---|---|
| MAP | 3105.40 | bulk, jumbo bags, 50 kg bags |
| DAP | 3105.30 | bulk, jumbo bags, 50 kg bags |
Buying MAP or DAP from Vietnam
VBT Global sources MAP and DAP from plants in Lào Cai province and trucks them to the port of loading on its own fleet. We quote bulk export lots to business buyers. MAP · DAP · Request a quotation