Relative efficacy and stability of biological and synthetic nitrification inhibitors in a highly nitrifying soil: Evidence of apparent nitrification inhibition by linoleic acid and linolenic acid

Summary

This laboratory study evaluated the relative efficacy of two plant-derived biological nitrification inhibitors (linoleic and linolenic acids) against the synthetic inhibitor dicyandiamide in a highly nitrifying soil. Whilst the biological compounds reduced soil nitrate concentrations, they operated through apparent indirect mechanisms—promoting microbial immobilisation rather than direct nitrifier suppression—and at high application rates increased gaseous emissions. The authors recommend future research distinguish carefully between direct and indirect inhibitory pathways when evaluating nitrification inhibitor compounds.

UK applicability

These findings are relevant to UK agricultural research on nitrogen loss mitigation, particularly for intensively managed soils prone to rapid nitrification and associated nitrate leaching. The work could inform evaluation of plant-derived nitrification inhibitors as alternatives to synthetic compounds in UK farming practice, though field validation would be needed before practical recommendation.

Key measures

Soil ammonium and nitrate concentrations, cumulative N₂O and CO₂ emissions, ¹⁴C-labelled inhibitor mineralisation rates over 38 days

Outcomes reported

The study compared the efficacy of biological nitrification inhibitors (linoleic and linolenic acids) versus synthetic inhibitor (dicyandiamide) on soil nitrogen dynamics, nitrous oxide and carbon dioxide emissions in a highly nitrifying soil. Researchers tracked inhibitor mineralisation and differentiated between direct nitrification inhibition and indirect effects on microbial nitrogen immobilisation.

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