Potassium Sulfate (SOP)
Also known as: Sulfate of Potash (SOP) Chemical Formula: K₂SO₄ Standard Grade: 0-0-50 + 17–18% S
Potassium Sulfate, commonly called Sulfate of Potash (SOP), is a premium chloride-free potassium fertilizer that supplies two essential nutrients — Potassium (K) and Sulfur (S). It is the preferred potassium source for chloride-sensitive crops and for situations where soil or irrigation water already contains high chloride levels.
SOP is produced either from natural mineral sources or through chemical processes (such as the reaction of potassium chloride with sulfuric acid). The final product is available in granular or crystalline form and is valued for its high purity and low salt index.
Technical Specifications
| Parameter | Unit | Standard / Typical Value |
|---|---|---|
| Potassium Oxide (K₂O) | % | 50 min (typically 50–52) |
| Sulfur (S) | % | 17–18 min |
| Chloride (Cl) | % | ≤ 0.5–2.5 max (low-Cl grades ≤ 0.5) |
| Moisture | % | 0.5 max (up to 1.5 in some grades) |
| Water Insoluble | % | ≤ 0.5–2.5 (depending on grade) |
| pH (solution) | — | Neutral to slightly alkaline |
| Appearance | — | White to off-white granules or crystals |
| Particle Size (granular) | — | Predominantly 1–4 mm or 2–4 mm |
| Bulk Density (approx.) | kg/m³ | 1,300–1,600 |
Typical Physical Properties
- Moderately to highly water-soluble (suitable for soil application and fertigation)
- Low salt index compared to MOP
- Free-flowing when dry
- Excellent compatibility for bulk blending
Key Benefits
- Chloride-free — Ideal for chloride-sensitive crops and saline soils.
- Dual nutrient supply — Delivers both potassium and sulfur in one product.
- Improves crop quality — Enhances fruit size, colour, sugar content, flavour, oil content, and shelf life.
- Supports plant resilience — Strengthens drought tolerance, disease resistance, and overall plant vigour.
- Lower risk of soil salinity — Safer option than MOP in areas with high chloride or sensitive crops.
- Sulfur contribution — Essential for protein synthesis, oil production, and enzyme activity (particularly valuable for oilseeds and legumes).
Note: SOP is generally more expensive than MOP (Potassium Chloride) due to its higher purity and chloride-free nature. It is therefore most cost-effective for high-value or chloride-sensitive crops.
Recommended Applications
Highly Recommended (Chloride-sensitive & high-value crops):
- Fruits: Grapes, berries, citrus, bananas, apples, pears
- Vegetables: Potatoes, tomatoes, carrots, lettuce, onions
- Cash crops: Tobacco, coffee, tea, almonds, nuts
- Oilseeds & legumes: Canola, sunflower, soybeans (where sulfur is also needed)
- Greenhouse, hydroponic, and fertigation systems
Also suitable for:
- Sulfur-deficient soils
- Areas with high chloride in soil or irrigation water
- Organic farming systems (certain certified grades available)
Application Methods:
- Soil application (broadcast or banded) — granular form
- Fertigation / drip irrigation — soluble grades
- Foliar spray (diluted solutions for quick correction of deficiencies)
- Bulk blending with other fertilizers
Typical rates depend on soil tests, crop, and growth stage (commonly 100–400 kg/ha for many high-value crops).
Packaging Options
- 50 kg polypropylene bags
- 1,000 kg jumbo bags (FIBC)
- Bulk (loose) delivery for large-scale operations
Storage & Handling Recommendations
- Store in a cool, dry, well-ventilated warehouse protected from moisture.
- Keep bags sealed and stacked on pallets to prevent caking.
- Avoid prolonged exposure to high humidity.
- Use standard personal protective equipment during handling.
Summary
Potassium Sulfate (SOP 0-0-50 + S) is the premium potassium fertilizer of choice when chloride sensitivity, crop quality, or sulfur supply are priorities. Its chloride-free composition and dual nutrient profile make it especially valuable for high-value horticultural crops, sensitive plants, and sulfur-deficient soils.
For commercial inquiries, current availability, soluble grades, or technical data sheets, please contact us.
