Urea: Characteristics
Biuret, granule size and why granules beat prills
What this tab covers The physical and chemical properties that set its grade, price and uses, with the commercial grades and the standards that define them.Buyers judge urea on nitrogen content, biuret (a plant-toxic by-product), moisture, granule size and strength. Granular urea blends and ships better and earns a premium over prills. Technical and DEF grades need much lower biuret, formaldehyde and metals.
Properties that matter commercially
| Property | Value / specification | Why it matters | Source |
|---|---|---|---|
| Nitrogen content | at least 46% N | price per unit N | India Fertiliser (Control) Order 1985 |
| Biuret | at most 1.5% (fertiliser) | toxic to plants, especially in foliar sprays | India Fertiliser (Control) Order 1985 |
| Moisture | at most 1.0% | caking and flow | India Fertiliser (Control) Order 1985 |
| Granule size | prilled 1-2.8 mm; granular 2-4 mm (indicative) | blending, spreading and handling | nitrogen tile (indicative) |
| DEF specification | 32.5% urea solution to ISO 22241 with very low biuret and metals | protects SCR catalysts | ISO 22241; Transport Topics (2012) |
Commercial grades
- Granular fertiliser urea
- Prilled fertiliser urea
- Neem-coated urea (India)
- Technical/industrial grade (resins, melamine)
- Automotive grade for DEF/AdBlue
- Feed grade
- Inhibitor-treated and polymer-coated urea