Nitrous oxide (N2O), a greenhouse gas, contributes to stratospheric ozone depletion. Agricultural fertiliser use and animal excreta dominate anthropogenic N2O emissions. Soil relative gas diffusivity (Dp/Do) has been used to predict the likelihood of soil N2O emissions, but limited information exists about how soil N2O emissions vary with soil type in relation to Dp/Do. It was hypothesised that, regardless of soil type, the N2O emissions would peak at the previously reported Dp/Do value of 0.006. Four pasture soils, sieved and repacked to three different bulk densities, were held at nine different soil matric potentials between near saturation and field capacity. Soil nitrate and dissolved organic matter concentrations were adequate for denitrification at all soil matric potentials. Increasing soil bulk density and soil matric potential caused Dp/Do to decline. As Dp/Do declined to a value of 0.006, the N2O fluxes increased, peaking at Dp/Do ≤ 0.006. This study shows that the elevation of N2O fluxes as a Dp/Do threshold of 0.006 is approached, holds across soil types. However, the variability in the magnitude of the N2O flux as Dp/Do declines is not explained by Dp/Do and is likely to be dependent on factors affecting the N2O : (N2O + N2) ratio.

中文翻译：

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土壤类型、容重和排水对相对气体扩散率和 N2O 排放的影响

一氧化二氮 (N2O) 是一种温室气体，会导致平流层臭氧消耗。农业肥料使用和动物排泄物在人为 N2O 排放中占主导地位。土壤相对气体扩散率 (Dp/Do) 已被用于预测土壤 N2O 排放的可能性，但关于土壤 N2O 排放如何随土壤类型相对于 Dp/Do 而变化的信息有限。假设无论土壤类型如何，N2O 排放都会在先前报告的 Dp/Do 值 0.006 处达到峰值。四种牧场土壤，过筛并重新包装成三种不同的体积密度，保持在接近饱和和田间持水量之间的九种不同土壤基质势。土壤硝酸盐和溶解有机质浓度足以在所有土壤基质势下进行反硝化。增加土壤容重和土壤基质势导致 Dp/Do 下降。随着 Dp/Do 下降到 0.006 的值，N2O 通量增加，在 Dp/Do ≤ 0.006 处达到峰值。该研究表明，当 Dp/Do 阈值接近 0.006 时，N2O 通量的升高适用于所有土壤类型。然而，随着 Dp/Do 下降，N2O 通量大小的变化不能用 Dp/Do 来解释，并且可能取决于影响 N2O : (N2O + N2) 比率的因素。