What Is Single Super Phosphate? | Fertiliser Guide

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Fertiliser Guide: What Is Single Super Phosphate?

Single super phosphate (SSP) is a widely used phosphorus-based fertiliser, commonly applied in agriculture and gardening to promote healthy root development and improve crop yield. It contains about 16–20% available phosphate (P₂O₅) and small amounts of calcium and sulphur, making it a valuable source of essential nutrients for plants.

SSP is one of the oldest chemical fertilisers still in use and is particularly effective in phosphorus-deficient soils.

How Is Single Super Phosphate Made?

SSP is manufactured by reacting phosphate rock with sulphuric acid. The chemical reaction produces monocalcium phosphate, which is water-soluble and therefore available for plant uptake, along with gypsum (calcium sulphate) as a by-product.

Chemical reaction:

Ca₃(PO₄)₂ + 2H₂SO₄ → Ca(H₂PO₄)₂ + 2CaSO₄

This process yields a greyish or brownish powder or granular product that can be easily applied to soil.

What Is SSP Used For?

SSP is used to:

  • Improve root growth, especially in young plants

  • Support flower and fruit development

  • Increase crop yields, particularly in cereal, oilseed, and vegetable crops

  • Provide sulphur, which is vital for protein synthesis in plants

  • Correct phosphorus deficiencies in soil

It’s often used in pastureland, arable farming, and home gardening, especially in soils low in phosphorus.

Pros and Cons of SSP

Pros:

  • Cost-effective phosphorus fertiliser

  • Contains sulphur, which many crops also need

  • Easy to apply and compatible with other fertilisers

  • Suitable for a wide range of soil types

Cons:

  • Has a lower phosphorus content compared to modern alternatives like triple super phosphate (TSP)

  • Not ideal for acidic soils, as SSP can further lower pH

  • Overuse can lead to phosphorus run-off, contributing to water pollution


How to Apply SSP

SSP is usually applied before or during planting, mixed into the soil, or used as a basal fertiliser. Application rates vary depending on crop type and soil condition, but a typical guideline is:

  • 200–400 kg per hectare for field crops

  • 20–50 grams per square metre for garden use

Always follow local agronomic advice or a soil test report to avoid over-fertilising.

Final Thought

Single super phosphate (SSP) remains a reliable, affordable fertiliser option for farmers and gardeners looking to improve phosphorus levels in the soil. While newer products offer higher concentrations, SSP still delivers a balanced dose of phosphorus, sulphur, and calcium — essential for strong, productive plants.