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Glossary

Biuret

Biuret is a by-product of urea synthesis that is toxic to plants; its content is strictly regulated in fertilisers.

biuret · C₂H₅N₃O₂ · NH₂-CO-NH-CO-NH₂

Biuret (C₂H₅N₃O₂) forms during the synthesis of urea through the condensation of two urea molecules, a reaction promoted by elevated temperatures and low NH₃ concentrations[1]. Being phytotoxic, it can scorch foliage when applied in foliar sprays.

The European regulation on fertilising products caps biuret at 12 g/kg of dry matter in solid inorganic macronutrient fertilisers and solid organo-mineral fertilisers[2]. Prilled urea and other fertiliser-grade urea should ideally keep levels below 1.2 %[1]. Technical urea destined for synthetic resins typically shows 0.3–0.4 %, with some buyers demanding under 0.15 %[1]. Organic fertilisers placed on the EU market must contain none at all[2].

Sources

  1. Commission européenne, BREF LVIC-AAF (2007), p. 352 · View the source
  2. Règlement (UE) 2019/1009 (produits fertilisants), ANNEX I · 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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