The effect of aggregation on diffusion of gases and vapours through soils

The effect of aggregate size upon the relationship between diffusion coefficient of gases through porous media and the porosity has been investigated. Over the range of aggregate sizes used, no differences were found. The presence of moisture in the soil was found to exert an influence directly related to the amount of water present, irrespective of the degree of aggregation of the soil. When the reduction in porosity due to the presence of water is calculated, the observations made fit the curve for air‐dry soils with fairly good agreement.