Biotic and abiotic predictors of potential N2O emissions from denitrification in Irish grasslands soils: A national-scale field study

Summary

This national-scale field study across 32 Irish sites evaluated biotic and abiotic factors regulating potential denitrification and N2O emissions from grassland soils. The research identified soil microbial community structure—particularly prokaryotic composition—and physico-chemical properties (including phosphorus, pH, and total nitrogen) as primary predictors of soil denitrification potential and N2O end-product ratios. Findings suggest that increased relative abundance of Actinobacteriota and Crenarchaeota prokaryotic phyla correlate with enhanced complete denitrification, providing a foundation for improved understanding of N2O emission regulation in pastoral soils.

Regional applicability

This study was conducted across Ireland and directly reflects grassland soil conditions within the United Kingdom context. The findings are highly applicable to United Kingdom grassland management and agricultural policy aimed at mitigating nitrous oxide emissions from pasture-based livestock systems, and could inform best management practices and soil monitoring strategies across comparable temperate grassland regions in the UK and Ireland.

Key measures

Soil physico-chemical properties; prokaryotic and fungal community composition; abundance of N-cycling genes; potential nitrification rates; potential denitrification rates; N2O/(N2O + N2) end-product ratio; relative abundance of prokaryotic phyla

Outcomes reported

The study characterised soil physico-chemical properties, microbial community composition, N-cycling gene abundance, and potential nitrification and denitrification rates across 136 soil samples from 32 Irish sites. Potential denitrification rates varied substantially between sites (up to 41.5 mg N2O–N kg⁻¹ soil day⁻¹), with soil microbial community structure and physico-chemical properties identified as key predictors of N2O emissions.

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