Soil physical properties may determine the fate of nitrous oxide (NO) in soil, but little is known about how soil compaction affects specific properties and their interactions. This study aimed to assess the impact of compaction on the soil pore functionality and architecture, and the effects on NO diffusion. Intact soil cores were sampled from lysimeters previously subjected to induced topsoil or subsoil compaction, as well as from uncompacted lysimeters. The soil cores were drained, sequentially, to −30, −50, and −100 h Pa to examine gas phase characteristics, each time followed by NO diffusion measurements after injecting NO at the bottom of the soil cores to simulate hotspots. Pore architecture was determined with X-ray microtomography. Results showed that soil compaction decreased pore volume, gas flow (convection and diffusion), and pore connectivity, and increased water-filled pore space, isolated pore ratios, and solid-to-pore distance, with a concomitant effect on NO diffusion. Changes in soil matric water potential did not influence the NO diffusion ratio (NO in the headspace/NO injected into the reservoir). The algorithmic evaluation of interacting effects revealed that pore connectivity was the best predictor for NO diffusion. In hierarchical order, the NO diffusion ratio could be explained by air permeability, pore connectivity and relative gas diffusivity. Multivariate analysis of functional and architectural pore characteristic parameters provided a comprehensive selection of factors driving NO diffusion within the soil layers. This is essential to understand the contribution of NO produced in agricultural soil to atmospheric emissions under climate change scenarios.

中文翻译：

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土壤孔隙网络对一氧化二氮命运的影响受土壤压实度、深度和水势的影响


土壤物理特性可能决定土壤中一氧化二氮（NO）的命运，但人们对土壤压实如何影响特定特性及其相互作用知之甚少。本研究旨在评估压实对土壤孔隙功能和结构的影响，以及对 NO 扩散的影响。完整的土芯是从先前经过诱导表土或底土压实的蒸渗仪以及未压实的蒸渗仪中取样的。将土芯依次排水至-30、-50和-100 h Pa以检查气相特征，每次在土芯底部注入NO以模拟热点后进行NO扩散测量。孔结构通过X射线显微断层扫描确定。结果表明，土壤压实降低了孔隙体积、气体流动（对流和扩散）和孔隙连通性，并增加了充水孔隙空间、孤立孔隙比率和固体与孔隙的距离，同时对 NO 扩散产生影响。土壤基质水势的变化不影响NO扩散比（顶部空间的NO/注入水库的NO）。相互作用效应的算法评估表明，孔隙连通性是 NO 扩散的最佳预测因子。按照层次顺序，NO 扩散率可以通过透气性、孔隙连通性和相对气体扩散率来解释。功能和结构孔隙特征参数的多变量分析提供了驱动土层内 NO 扩散的因素的综合选择。这对于了解气候变化情景下农业土壤中产生的 NO 对大气排放的贡献至关重要。