Potassium Nitrate (KNO₃) is a high-purity, fully water-soluble potash fertilizer supplying two immediately available nutrients—potassium (K) and nitrate nitrogen (NO₃⁻). Being completely chloride-free, it is ideal for fertigation, foliar feeding, hydroponics, and high-value, chloride-sensitive crops.
Product Identification
| Parameter | Specification |
|---|---|
| Chemical Name | Potassium Nitrate |
| Chemical Formula | KNO₃ |
| Fertilizer Grade | 13-0-46 |
| Category | Fully water-soluble, chloride-free potassic fertilizer |
| Nature | Chemically refined inorganic salt |
Chemical Composition & Structure
| Component | Typical Content |
|---|---|
| Nitrogen (as NO₃⁻-N) | 12.5 – 13.5% |
| Potassium (as K₂O) | 44 – 46% |
| Chloride (Cl⁻) | Nil |
| Sodium (Na) | ≤ 0.5% |
| Moisture | ≤ 0.3% |
Potassium nitrate is an ionic compound composed of potassium (K⁺) and nitrate (NO₃⁻) ions. Nitrate nitrogen is immediately available to plants, and the fertilizer exhibits a neutral reaction in soil solution.
Physical Properties
| Property | Typical Value |
|---|---|
| Appearance | White crystalline solid |
| Bulk Density | 1.05 – 1.10 g/cm³ |
| Particle Form | Crystalline / prilled |
| Solubility in Water | ~31 g/100 g at 20 °C |
| Hygroscopicity | Low |
| Melting Point | ~334 °C (decomposes) |
Mechanical Properties (Handling Behavior)
✔ Moderate crush strength
✔ Medium abrasion resistance
✔ Low dust formation
✔ Low caking tendency under dry storage
📌 KNO₃ is less mechanically robust than MOP or SOP but suitable for bag handling and precision application systems.
Crystallization & Structural Stability
✔ Orthorhombic crystal structure
✔ Strength dependent on crystal size and drying conditions
✔ No metallurgical behavior (non-metallic salt)
Thermal & Chemical Behavior
Thermal Behavior:
Decomposes above ~334 °C
Releases oxygen and nitrogen oxides
Acts as an oxidizing agent at elevated temperatures
Chemical Reactivity:
Highly soluble and non-volatile
Compatible with most water-soluble fertilizers
Key Agronomic Characteristics
✔ Supplies two immediately available nutrients
✔ Nitrate nitrogen ensures fast vegetative response
✔ Potassium enhances fruit development and stress tolerance
✔ Improves fruit size, color, sugar accumulation, and firmness
✔ Enhances calcium and magnesium uptake
Manufacturing & Processing
Manufacturing Routes:
✔ Double decomposition (NaNO₃ + KCl → KNO₃ + NaCl)
✔ Nitric acid neutralization
✔ Crystallization and purification
✔ Drying and screening
Process Controls:
Crystal purity
Moisture removal
Particle size control
Available Forms
Crystalline KNO₃ (fertigation & foliar use)
Prilled potassium nitrate
Fertilizer-grade water-soluble KNO₃
Technical-grade potassium nitrate
Applications
Agriculture:
Fruits (grapes, apple, citrus, banana)
Vegetables (tomato, capsicum, cucumber)
Floriculture, greenhouse crops, hydroponics
Commonly used in fertigation, foliar spray, and precision nutrient programs
Industrial:
Specialty glass
Fireworks and pyrotechnics
Pharmaceuticals
Food preservation (regulated)
Advantages of Potassium Nitrate
Agronomic:
✔ Fully water-soluble
✔ Chloride-free
✔ Nitrate nitrogen avoids soil acidification
✔ Rapid crop response
✔ Ideal for drip irrigation
Commercial:
✔ Premium fertilizer category
✔ Consistent quality
✔ High demand in protected cultivation
✔ Easy nutrient management
Limitations & Considerations
Higher cost than MOP and SOP
Nitrate nitrogen prone to leaching
Not suitable as a sole nitrogen source
Requires careful fertigation scheduling
KNO₃ vs SOP vs MOP
| Parameter | KNO₃ | SOP | MOP |
|---|---|---|---|
| K₂O (%) | 46 | 50 | 60 |
| Nitrogen | Yes (NO₃) | No | No |
| Sulfur | No | Yes | No |
| Chloride | Nil | Nil | High |
| Best Use | Fertigation | Soil application | Bulk field crops |
| Cost | Very High | High | Low |
Why Choose Potassium Nitrate?
✔ Best fertilizer for fertigation and foliar feeding
✔ Immediate nutrient uptake
✔ Ideal for high-value and export crops
✔ Improves fruit quality and yield
✔ Safe for chloride-sensitive crops
Storage & Handling
Store in cool, dry, well-ventilated areas
Avoid contact with combustible materials
Use moisture-proof bags
Follow FIFO practices
Soil Suitability Summary
| Soil Type | Suitability |
|---|---|
| Neutral soils | Excellent |
| Acidic soils | Excellent |
| Saline soils | Very good |
| Sandy soils | Good (split doses) |