Fig. 3. Soil-gas diffusivities D_p/D₀ as a function of air-filled porosity : (a) all matric-potential () measurements for lysimeter soils (Rønhave, Foulum, and Jyndevad); (b) all measurements for field soils (Gjorslev and Mammen); (c) measurements from C horizon samples with different soil textures at Mammen; and (d) measurements from sandy clay loam layers from Foulum, Gjorslev, and Mammen. Note different axes and log scale.