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Potassium Sulphate (00-00-50): Composition, Benefits, and Dosage

Potassium Sulphate (00-00-50), also known as Sulphate of Potash (SOP), is a 100% water-soluble fertilizer containing 50% Potash (K2O) and 17.5% Sulphur. It provides chloride-free potassium essential for fruit sizing, color development, and drought resistance under the Fertilizer Control Order (FCO).

Last reviewed: 10 November 2026

Nutrient Composition and Agronomic Importance

SOP supplies high concentrations of bioavailable potassium alongside sulfur without introducing chloride ions. Potassium regulates stomatal opening, enzyme activation, and carbohydrate translocation from leaves to reproductive sinks (fruits, grains, tubers).

Its virtually chloride-free profile makes it indispensable for intensive fertigation in high-value horticulture.

  • Chloride-sensitive crops: Ideal for grapes, potatoes, onions, tobacco, pomegranates, and berries that suffer leaf burn and quality reduction from chloride in MOP (Muriate of Potash).
  • Quality enhancement: Improves fruit size, brix (sweetness), shelf life, uniform color, and mechanical strength of skin.
  • Sulfur synergy: Sulfur supports essential amino acid synthesis (methionine, cysteine) and enhances oil content in oilseeds.

Fertigation and Foliar Application Best Practices

Potassium Sulphate dissolves cleanly in water, making it suited for drip fertigation and foliar spraying during fruit development, bulking, and maturation stages.

Managing water solubility parameters prevents nozzle precipitation and optimizes plant uptake rates.

  • Timing: Apply primarily during reproductive, fruit-filling, or tuber-bulking phases when crop potassium demand reaches its peak.
  • Tank mixing: Compatible with most soluble fertilizers; avoid mixing directly with highly concentrated calcium salts in the same mother tank to prevent calcium sulfate precipitation.
  • Drip fertigation: Flush drip lines with clean water after fertigation to maintain line hygiene and avoid emitter clogging.

Official source

Check the latest rules, benefits and forms here. KisanPe is an independent platform and is not a government website.

Department of Fertilizers ↗

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Common questions

What nutrients are present in 00-00-50 fertilizer?

It contains 50% water-soluble Potassium (as K2O) and approximately 17.5% bioavailable Sulphur (S) with minimal chloride.

How is 00-00-50 different from 00-00-60 (MOP)?

00-00-50 is Sulphate of Potash (SOP), completely free of harmful chloride and containing sulfur, whereas 00-00-60 is Muriate of Potash (MOP) containing around 47% chloride.

When should 00-00-50 be applied to crops?

It is best applied during fruit enlargement, grain filling, or tuber maturation to improve size, sugar content, color, and post-harvest shelf life.

General guidance, not personal advice. For your farm, ask your local Krishi Vigyan Kendra or agriculture officer.

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