Soil-gas diffusivity plays a fundamental role in diffusion-controlled migration of gases which is important in relation to soil aeration and climate gas emissions. Gas diffusivity is a function of soil type and soil structure (e.g., density) and therefore typically shows a depth-dependent behaviour. This study investigated the gas diffusivity in repacked soils taken from past literature studies. The soils were pre-characterized for particle-size distribution, organic matter content, dry density and particle density. Soil-gas diffusivity and soil-water characteristics were measured using one-chamber diffusion apparatus and sandbox, respectively. The measured diffusivity of selected repacked soil data from literature were tested against the existing predictive gas diffusivity models. A descriptive parametric two-region model was developed considering scaling factors and shape factors representing two-region behaviour of each selected soil. This two-region model performed statistically better than other predictive models for all the repacked soils.
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