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Abstract
Anoxic soil pores govern carbon retention and the release of potent greenhouse gases like N2O and CH4 in agricultural soils. Soil pore-size distribution (PSD) and pore continuity have been known to qualitatively impact oxygen diffusion, a key driver of potential soil anoxia. In this study, this effect was quantified. Soil moisture affected the relationship between PSD and oxygen diffusion and the contribution of pore sizes to potential anoxic volume (POV). Pores ≤ 1 micron contributed significantly to POV in the field, sustaining potentially anoxic conditions for at least 48 hours, while pores > 3 microns had negligible impact. Additionally, the dependence of oxygen diffusivity (OD) on soil structure was quantifiably characterized at different moisture contents. Results showed that van Genuchten’s parameters n1 and n2, representing soil PSD for a dual porosity system, successfully classified OD for low moisture contents. Results from this research can aid in promoting sustainable agricultural practices.