superfosfater

Superfosfater are phosphorus-containing mineral fertilizers produced by treating phosphate rock with acids to convert insoluble phosphate into plant-available forms. They are mainly used to supply phosphorus, a critical nutrient for root development and early growth in crops.

There are two principal varieties. Single superphosphate (SSP) is made by reacting phosphate rock with sulfuric acid. It typically contains about 16–20% P2O5 and includes calcium sulfate, or gypsum, as a byproduct. Triple superphosphate (TSP) is produced by reacting phosphate rock with phosphoric acid, yielding a higher concentration of P2O5, typically around 40–46%, with less or no gypsum byproduct. SSP is more acidic and can also contribute calcium and sulfur, while TSP is more concentrated and generally more expensive.

Usage and application methods vary with soil conditions and crop needs. Superfosfater are usually applied as a basal fertilizer at planting or incorporated into the soil before seeding. They improve early root growth and establishment by supplying readily available phosphorus. On soils with adequate phosphorus, responses are limited, and excessive application can be wasteful and potentially contribute to environmental issues.

Advantages of superfosfater include relatively immediate phosphorus availability and ease of handling compared with raw phosphate rock. Limitations involve potential phosphorus fixation in certain soils, diminished efficiency in strongly acidic or alkaline conditions, and environmental concerns such as phosphorus runoff and eutrophication if over-applied. Storage requires protection from moisture, as both SSP and TSP can absorb water and degrade in damp conditions.

Historically, superphosphates played a key role in expanding agricultural yields since the 19th century and remain common in many regions as part of broader phosphorus management strategies.