Soil aeration (i.e., soil air content and composition) is of major importance in agricultural and environmental practices. Poor aeration reduces plant growth, development, yield, and resistance to diseases and other abiotic stresses (e.g., salinity). In many soils contaminated with hydrocarbons, low O₂ supply limits the rate of contaminant decomposition and prolongs remediation. Soil aeration is governed by diffusion of O₂ from the atmosphere and countercurrent diffusion of CO₂ to the atmosphere. Injection of air (with an atmospheric O₂ concentration of 20.9%) into poorly aerated soils is expected to improve soil aeration by enriching it with O₂ and extracting CO₂. In addition, air flow causes redistribution of soil water. Water redistribution is affected by operational (discharge rate, frequency, duty cycle) and geometrical (depth and distance between sources) air injection parameters, soil parameters (e.g., water retention and conductivity), and irrigation geometry and scheduling. We studied forced one‐ and three‐dimensional air (or N₂) and water injection into packed wet sand and analyzed the effect of air injection on soil aeration and water redistribution in granular media. The study demonstrates the applicability of the Darcy–Buckingham law to air flow at different degrees of water saturation and for a large relevant range of capillary numbers. We also suggest a simple method to measure the soil's conductivity to air (Darcy's constant) for different air contents and use a simple analytical solution to estimate O₂ diffusion from the atmosphere. We discuss the effect of operational air injection parameters on aeration's effectiveness and efficiency.

中文翻译：

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强制注气和水渗透到沙中—两相流桶和塔的实验

在农业和环境实践中，土壤通气（即土壤中的空气含量和组成）至关重要。通气不良会降低植物的生长，发育，产量以及对疾病和其他非生物胁迫（例如盐度）的抵抗力。在许多被碳氢化合物污染的土壤中，低的O ₂供应限制了污染物的分解速度并延长了修复时间。土壤通气由O ₂从大气中的扩散和CO ₂向大气的逆流扩散控制。空气的喷射（与大气ö ₂的20.9％浓度）到通气不良的土壤预计带O富集它来改善土壤通气₂和提取CO ₂。另外，空气流动导致土壤水的重新分配。水的再分配受到操作（排放率，频率，占空比）和几何形状（源之间的深度和距离）的空气注入参数，土壤参数（例如保水率和电导率）以及灌溉几何形状和调度的影响。我们研究了强制的一维和三维空气（或N ₂）和注水到填充的湿沙中，并分析了注水对颗粒介质中土壤通气和水分再分配的影响。该研究证明了达西-白金汉定律在不同程度的水饱和度和较大的相关毛细管数范围内对气流的适用性。我们还建议一种简单的方法来测量不同空气含量下土壤对空气的电导率（达西常数），并使用简单的分析解决方案来估算O ₂从大气中的扩散。我们讨论了操作空气注入参数对曝气效果和效率的影响。