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Influence of soil aeration status on denitrifier gene expression and denitrification gas fluxes (N2O and N2) from repacked pasture soils
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Influence of soil aeration status on denitrifier gene expression and denitrification gas fluxes (N2O and N2) from repacked pasture soils

Juan Liu, Timothy Clough, Sam Carrick, Jiafa Luo, Andriy Podolyan, Naomi Wells, Jupei Shen, Peng Li, Lianfeng Du, Hong Pan, …
Soil biology & biochemistry, Vol.222, pp.1-12
11/2026
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Published (Version of record) Open CC BY-NC-ND V4.0

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Abstract

denitrifier expression N2 flux N2O flux Soil aeration status soil matric potential soil relative gas diffusivity (Dp/Do)
Pasture soils are major sources of nitrous oxide (N2O), a potent greenhouse gas mainly produced through microbial denitrification. However, interactions between soil aeration status and microbial responses involved in regulating N2O emissions remain poorly understood. We investigated denitrifier gene expression together with N<sub>2</sub>O and dinitrogen (N<sub>2</sub>O) emissions using repacked cores of three pasture soils with contrasting bulk densities incubated across ten matric potentials (−1 to −10 kPa). Peak N<sub>2</sub>O fluxes occurred at matric potentials of −1 to −2 kPa and were strongly related to relative gas diffusivity (D<sub>p</sub>/D<sub>o/sub>) and water-filled pore space (WFPS). In contrast, the expression of nirS, norB, and nosZ was more closely associated with matric potential and volumetric water content than with (D<sub>p</sub>/D<sub>o/sub>) and WFPS. However, denitrifier gene transcription alone did not explain the observed gaseous N emissions, indicating that microbial transcriptional responses and measured N fluxes were decoupled under changing soil aeration conditions. These findings suggest bulk soil aeration indices (e.g. (D<sub>p</sub>/D<sub>o/sub>) or WFPS) do not fully represent the local conditions regulating microbial response, whereas measured gaseous N emissions are additionally constrained by soil physical processes governing gas transport. Overall, these results highlight the importance of integrating microbial responses with soil physical processes to improve our mechanistic understanding of N<sub>2</sub>O emissions from grazed pasture soils.

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