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Glossary

Phosphate solubility

Phosphorus solubility determines how readily this nutrient becomes available to plants, and is used to classify phosphate fertilisers by their immediate or delayed effectiveness.

P solubility · phosphate solubility · soluble P

Phosphorus solubility gauges the ability of phosphate compounds to dissolve in water or extracting solutions, which governs their accessibility to roots. Water-soluble fertilisers — SSP, TSP, DAP and MAP — are suited to slightly acidic through to neutral and alkaline soils, particularly for short-cycle crops[1]. Ground phosphate rock and Thomas slag, being poorly soluble, require soil acidity and biological activity; their low solubility restricts adsorption in soils high in iron or aluminium[1]. EU regulation mandates that 40% of total phosphorus (P) be water-soluble or 75% soluble in neutral ammonium citrate[2]. Only 15 to 20% of applied phosphorus is recovered by the crop[3].

Sources

  1. FAO, Plant nutrition for food security (2006), p. 217 · View the source
  2. Règlement (UE) 2019/1009 (produits fertilisants), ANNEX III · View the source
  3. FAO, Plant nutrition for food security (2006), p. 84 · View the source
  4. Commission européenne, BREF LVIC-AAF (2007), p. 415 · View the source

Original text by fertiliser-market.com. Facts and figures are taken from the documents cited, at the page given; no text, table or chart is reproduced from them.

Updated October 27, 2026

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