Single superphosphate

SSP is manufactured by treating phosphate rock with sulfuric acid, producing a mixture of water-soluble monocalcium phosphate and calcium sulfate. Its guaranteed analysis is typically around 16% P₂O₅, along with roughly 18–21% calcium and 11–12% sulfur, depending on the source rock and process.

Phosphorus content

About 16% P₂O₅, largely water-soluble

Calcium content

Substantial, from calcium phosphate and gypsum

Sulfur content

Substantial, from the gypsum co-product

Manufacture

Phosphate rock acidulated with sulfuric acid

SSP supplies phosphorus in a largely water-soluble form, together with meaningful amounts of both calcium and sulfate-sulfur, making it a multi-nutrient product despite its lower phosphorus concentration relative to triple superphosphate.

• Phosphorus is water-soluble and plant-available soon after application
• Calcium and sulfate-sulfur are supplied as substantial secondary nutrients
• No nitrogen or potassium is supplied

SSP is valued where a combined supply of phosphorus, calcium, and sulfur is useful, such as on legumes and oilseed crops with a sulfur requirement, and in cropping systems where its lower analysis and bulkier form are not a significant handling constraint.

• Supplies three nutrients — phosphorus, calcium, and sulfur — in one product
• Useful on crops and soils with a sulfur requirement alongside phosphorus need
• Long-established product with a well-understood soil behaviour

As with other phosphate fertilizers, placement near the root zone improves phosphorus uptake efficiency because phosphorus is largely immobile in soil, while the sulfur and calcium components behave more like the sulfate and calcium supplied by other sources.

Phosphorus loss through erosion and runoff remains the main environmental concern common to phosphate fertilizers, while the sulfate component behaves similarly to other soluble sulfate sources, being mobile in the soil solution.