Fertilizers / DAP 18-46-0 / Specifications
DAP data sheet
DAP 18-46-0 Specifications and Data Sheet
Diammonium phosphate is sold on a well-known analysis, 18-46-0, but the details still differ between suppliers: granule size, moisture, strength and sulphur. Below are two typical DAP specifications from supplier data sheets, side by side, with the chemistry behind them.
- N 18% min
- P₂O₅ 46% min
- Granular
Chemistry
What diammonium phosphate is
DAP is diammonium hydrogen phosphate, made by reacting phosphoric acid with ammonia and granulating the result. As a pure compound it would analyse about 21-53-0. Fertilizer-grade DAP is made from phosphoric acid that carries impurities from the phosphate rock, so the standard commercial grade is 18-46-0.
DAP is the most concentrated phosphate-based fertilizer in common use. When a granule dissolves, it temporarily makes the soil solution around it more alkaline, which can help phosphorus uptake on acid soils.
(NH4)2HPO4
Chemical formula of diammonium hydrogen phosphate.
CAS 7783-28-0
The identifier used in safety data sheets and customs documents.
21-53-0 pure
Pure compound analysis; fertilizer grade is 18-46-0.
Water soluble
About 42% water-soluble P2O5 in typical analyses.
Specification A
Granular DAP, 1 to 6 mm
| Specification A: granular DAP | Result |
|---|---|
| Grade | NP 18-46 |
| Nitrogen (N) | 18% |
| Phosphate (P2O5) | 46% |
| Sulphur (S) | 2.5% |
| pH | 6.0 to 7.2 |
| Granulometry, 1 to 6 mm | ≥ 95% |
| Granule strength | 6.0 MPa minimum |
| Moisture | 1% maximum |
| Bulk density | About 1 t/m³ |
The supplier confirms this product meets the contaminant limits for cadmium, chromium, mercury, nickel, lead and arsenic in Regulation (EU) 2019/1009 on fertilising products.
Specification B
Typical analysis, 2 to 4 mm
| Specification B: typical analysis | Typical | Guarantee |
|---|---|---|
| Total nitrogen (N) | 18% | 18% minimum |
| Available phosphate (P2O5) | 46% | 46% minimum |
| Water-soluble phosphate (P2O5) | 42% | – |
| Moisture (H2O) | 2.2% | – |
| Bulk density, loose | 930 kg/m³ (58 lb/ft³) | – |
| Angle of repose | 37° | – |
| Sizing, 2 to 4 mm | ≥ 90% | – |
| Size Guide Number (SGN) | 295 | – |
| Uniformity Index (UI) | 55 | – |
Average properties of composite samples. Individual shipments may fall outside these typical values, and handling, transport or long storage can affect the analysis.
Reading the numbers
What to check in a DAP specification
Nutrients
Total N and available P2O5 as minimums, plus water-soluble P2O5 if your market requires it.
Granule size
A tight range blends and spreads evenly. Compare the size range and the share inside it.
Granule strength
Strong granules survive handling and long voyages with less dust.
Moisture
Low moisture reduces caking. Limits range from 1% maximum to about 2% typical.
Contaminants
Cadmium and other heavy metals, where your destination sets limits.
Packing
50 kg bags, 1,000 kg jumbo bags or break bulk, with the marking your country requires.
Enquiry
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- 50 kg bags
- 1,000 kg jumbo bags
- Break bulk
Frequently asked questions
What does 18-46-0 mean?
It is the nutrient analysis of DAP: 18% nitrogen (N), 46% phosphate (P2O5) and 0% potash (K2O) by weight.
What is the chemical formula of diammonium phosphate?
The formula is (NH4)2HPO4. Its chemical name is diammonium hydrogen phosphate, and its CAS number is 7783-28-0.
Why is fertilizer DAP 18-46-0 and not higher?
Pure diammonium hydrogen phosphate contains about 21% nitrogen and 53% P2O5. Fertilizer-grade DAP is made from phosphoric acid that contains impurities, so the commercial standard is 18-46-0.
What granule size is DAP?
Typical specifications ask for at least 95% of granules between 1 and 6 mm, or at least 90% between 2 and 4 mm.
Does DAP contain sulphur?
Some grades do. One of the specifications on this page lists 2.5% sulphur. Confirm the sulphur content in your contract if it matters for your crop.
Are the specifications guaranteed?
No. Typical properties are for information only. The contract specification and the inspection certificate at loading are what count.
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