Review of recent progress for predicting gas transport parameters in undisturbed andisols: Campbell b dependent models for gas diffusivity and air permeability

This paper reviews and connects recent studies on gas transport parameter models for Japanese volcanic ash soils (Andisols). Soil water retention from +kPa to +./MPa of matric potential for di#erently-textured, undisturbed Andisols from three prefectures in Japan was well described by the simple Campbell (+31.) model. Gas di#usivity in the same matric potential range was well predicted by two recent soil type (Campbell b) dependent models, while the classical Millington and Quirk (+30+) model markedly under-predicted gas di#usivity for all Andisols. Air permeability (ka) in wet to medium moist soil (from + to +**kPa of matric potential) was also well predicted by a Campbell b dependent model, provided that ka at +*kPa of matric potential was measured and used as a reference point in the model. In conclusion, Campbell-based models appear highly useful for describing pore characteristics and predicting gaseous phase transport parameters in Andisols.