Ammonium sulfate is an inorganic nitrogen–sulfur fertilizer with the chemical formula (NH₄)₂SO₄. It supplies nitrogen in ammoniacal form and sulfur in sulfate form, making it highly effective in sulfur-deficient soils, alkaline regions, and rice-based cropping systems.
Chemical Composition
| Component | Typical Content |
|---|---|
| Total Nitrogen (N) | 20.5–21.0% |
| Ammoniacal Nitrogen | ~21% |
| Sulfur (S) | 23–24% |
| Sulfate (SO₄²⁻) | ~60% |
| Hydrogen (H) | ~6% |
| Oxygen (O) | ~53% |
| Molecular Weight | 132.14 g/mol |
| Chemical Formula | (NH₄)₂SO₄ |
✔ Dual-nutrient fertilizer
✔ 100% water-soluble nutrients
Key Physical Properties
| Property | Typical Value |
|---|---|
| Appearance | White to off-white crystalline solid |
| Physical Form | Crystals / Granules |
| Bulk Density | 960–1,100 kg/m³ |
| True Density | ~1.77 g/cm³ |
| Melting Point | Decomposes >235 °C |
| Solubility in Water | High |
| Hygroscopicity | Low |
| pH (aqueous solution) | ~5.0–5.5 |
| Thermal Stability | High (non-volatile) |
📌 Stable under humid conditions
📌 Suitable for long-term storage
Mechanical Properties
| Property | Typical Behavior |
|---|---|
| Granule Hardness | High |
| Crush Strength | 3–5 kg/granule |
| Abrasion Resistance | Good |
| Flowability | Excellent |
| Caking Tendency | Very Low |
| Dust Formation | Low |
✔ Excellent mechanical stability
✔ Ideal for bulk handling and blending
Production & Processing
Ammonium sulfate is produced by neutralization of ammonia with sulfuric acid or recovered as a by-product from caprolactam production, coke oven gas processing, and flue-gas desulfurization.
2NH₃ + H₂SO₄ → (NH₄)₂SO₄
Applications
Agriculture: Paddy rice, oilseeds, pulses, sugarcane, tea, coffee, vegetables, sulfur-deficient soils
Industrial: Fertilizer blends, water treatment, specialty chemicals
Advantages
✔ Supplies sulfur along with nitrogen
✔ Very low nitrogen loss
✔ Excellent storage stability
✔ Suitable for alkaline & calcareous soils
✔ Safe, non-explosive fertilizer
Ammonium Sulfate vs Other Nitrogen Fertilizers
| Feature | Ammonium Sulfate | Urea | CAN |
|---|---|---|---|
| Nitrogen % | 21% | 46% | 26% |
| Sulfur Supply | Yes | No | No |
| Volatilization Loss | Very Low | High | Low |
| Hygroscopicity | Low | Moderate | Low |
| Soil Reaction | Acidifying | Neutral | Neutral |
| Safety | Very High | High | High |