Urea is a highly concentrated nitrogen fertilizer with the chemical formula CO(NH₂)₂, containing 46% nitrogen—the highest nitrogen content among solid fertilizers. It is widely used in agriculture to promote healthy plant growth, leaf development, and higher crop yields. Urea accounts for over 50% of global nitrogen fertilizer consumption.
Chemical Composition
| Component | Content |
|---|---|
| Nitrogen (N) | 46% |
| Carbon (C) | 20.00% |
| Hydrogen (H) | 6.70% |
| Oxygen (O) | 26.60% |
| Molecular Weight | 60.06 g/mol |
| Chemical Formula | CO(NH₂)₂ |
✔ Neutral organic compound
✔ Highly nitrogen-dense
Key Physical Properties
| Property | Typical Value |
|---|---|
| Appearance | White crystalline solid |
| Physical Form | Granules / Prills |
| Bulk Density | 720–770 kg/m³ |
| True Density | ~1.32 g/cm³ |
| Melting Point | 133 °C |
| Decomposition Temperature | >135 °C |
| Solubility in Water | Very high |
| Hygroscopicity | Moderate–High |
| pH (10% solution) | ~7.0–7.5 |
Mechanical Properties
| Property | Typical Range |
|---|---|
| Hardness | Moderate |
| Crush Strength | 2–4 kg/granule |
| Abrasion Resistance | Moderate |
| Flowability | Good (granular grade) |
| Caking Tendency | Moderate–High |
| Dust Formation | Low–Moderate |
⚠ Mechanical integrity is critical for bulk handling
⚠ Granular urea preferred for blending
Industrial Production
Urea is produced by reacting ammonia and carbon dioxide under high pressure and temperature.
2NH₃ + CO₂ → NH₂COONH₄ (Carbamate)
NH₂COONH₄ → CO(NH₂)₂ + H₂O (Dehydration)
Process Conditions
Pressure: 140–250 bar
Temperature: 170–200 °C
Highly integrated with ammonia plants
Available Forms
Prilled urea
Granular urea
Neem-coated urea
Sulfur-coated urea
Urea briquettes
Liquid urea (UAN blends)
Applications
Agriculture: Paddy, wheat, maize, sugarcane, vegetables
Industrial: Melamine, urea-formaldehyde resins, DEF / AdBlue
Environmental: NOₓ reduction (SCR), wastewater treatment
Advantages
✔ Highest nitrogen concentration
✔ Lowest cost per kg of nitrogen
✔ Rapid plant availability
✔ Flexible application methods
✔ Essential for modern intensive farming
Urea vs Other Nitrogen Fertilizers
| Feature | Urea | Ammonium Nitrate | Ammonium Sulfate |
|---|---|---|---|
| Nitrogen % | 46% | 34% | 21% |
| Sulfur | No | No | Yes |
| Hygroscopicity | Moderate | High | Low |
| Cost per kg N | Lowest | High | Moderate |
| Volatilization Risk | High | Low | Low |
Urea fertilizer is the most efficient and widely used solid nitrogen fertilizer, offering maximum nitrogen concentration, flexibility, and cost efficiency when applied with proper handling and management.