Occurrence and 15N-quantification of simultaneous nitrification and denitrification in N-fertilised soils incubated under oxygen-limiting conditions

Summary

This laboratory study employed 15N stable isotope tracing to quantify the contribution of simultaneous nitrification-denitrification (SND) to nitrogen loss in fertilised soils incubated under oxygen-limiting conditions. The work addresses a methodological gap in distinguishing between parallel nitrification and denitrification pathways operating concurrently in anaerobic soil microenvironments, which is critical for accurate prediction of nitrogen fate in waterlogged or poorly aerated agricultural soils. The findings provide mechanistic insights into nitrogen cycling in fertilised systems subject to periodic anaerobiosis.

UK applicability

The findings are relevant to UK agricultural soils, particularly in poorly drained clay soils and winter-waterlogged fields common in UK farming, where SND may represent a significant pathway for nitrogen loss from synthetic fertiliser applications. The quantitative data on SND contributions could inform nitrogen management practices and emission predictions under UK soil and climatic conditions.

Key measures

15N-labelled nitrogen transformations; nitrification rates; denitrification rates; proportion of total N loss attributable to SND pathway

Outcomes reported

The study quantified the relative contribution of simultaneous nitrification-denitrification (SND) to total nitrogen loss in nitrogen-fertilised soils under oxygen-limiting conditions using 15N isotope tracing. It measured the concurrent rates of nitrification and denitrification pathways operating within anaerobic soil microenvironments.

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