What Is Superphosphate (SSP) Fertilizer and Why Is It Important for Crop Growth?

Technical Introduction

Superphosphate (SSP, Single Superphosphate) is the first commercial phosphorus fertilizer ever produced, developed in the mid-19th century.
It is made by treating phosphate rock with sulfuric acid (H₂SO₄), producing a mixture of monocalcium phosphate [Ca(H₂PO₄)₂] and gypsum (CaSO₄·2H₂O).

SSP typically contains 16–20% P₂O₅ in water-soluble form, along with valuable secondary nutrients like calcium and sulfur, making it a multi-nutrient fertilizer.

Applications

1. Agriculture

• Field Crops: Especially effective for oilseeds, pulses, wheat, maize, and sugarcane.

• Sulfur-Loving Crops: Crucial for crops like onion, garlic, mustard, and legumes that require sulfur.

• Soil Conditioner: Provides calcium and sulfur in addition to phosphorus.

• Direct Application or Blending: Used as a straight fertilizer or as a raw material in blends.

2. Industrial Uses

• Raw material for producing other phosphate fertilizers.

• Feed supplements (after processing).

Advantages

• Multi-Nutrient Supply: Provides phosphorus, calcium, and sulfur simultaneously.

• Cost-Effective: Lower price compared with TSP, MAP, and DAP.

• Soil Amendment: Improves soil structure with added gypsum.

• Suitable for Sulfur-Deficient Soils: Corrects dual nutrient deficiencies.

Typical Parameters

FAQs

Q1: How is SSP different from TSP?
A1: SSP has 16–20% P₂O₅ while TSP has 44–48% P₂O₅. SSP also provides sulfur and calcium, whereas TSP is almost pure phosphorus.

Q2: Which crops benefit most from SSP?
A2: Oilseeds, legumes, onion, garlic, and crops grown in sulfur-deficient soils.

Q3: How should SSP be applied?
A3: Typically applied at planting in bands near the seed or broadcast and incorporated into soil.

Q4: Is SSP suitable for acidic soils?
A4: Yes, but continuous use may slightly increase soil acidity due to the presence of gypsum.

Q5: Why is SSP still used when TSP, DAP, and MAP exist?
A5: Because SSP is cheaper and provides multiple nutrients (P, S, Ca) in one application.