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Ecotoxicological information

Toxicity to soil macroorganisms except arthropods

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Description of key information

Application of urea (in common with other nitrogen fertilisers) releases ammoniacal-N which is nitrified to nitrate: an acidic species that causes gradual lowering of soil pH unless the effect is counteracted by lime application.  This is not a direct effect of exposure to urea.  

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Effects of long term use of urea fertiliser at 60, 120 and 180 kg N/ha/year was assessed on lumbricid earthworms in uncultivated turfgrass on loamy sand soil. The test sites were treated twice yearly for 20 years. Urea fertiliser reduced earthworm numbers and biomass and lowered pH. It was concluded that application of nitrogenous fertilisers for long periods may have a deleterious effect on earthworms in the absence of liming (Wei-Chum et al, 1990).

The substances urea and phosphoric acid do have a very high water solubility and its chemical properties do not indicate bioaccumulation and/or adsorption to soil. Therefore, the study is not considered necessary. In addition, Phosphoric acid will infiltrate and migrate downward due to its high water solubility. In the process they can dissolve some soil materials and be partially neutralized in the process. On reaching the ground water phosphoric acid will be dispersed and diluted.