Fig. 4. Soil-gas diffusivities D_p,100/D₀ as a function of air-filled porosity ₁₀₀ for (a) lysimeter soils (Rønhave, Foulum, and Jyndevad), (b) field soils (Rønhave, Foulum, and Jyndevad) (Schjønning, 1985b), and (c) field soils (Gjorslev and Mammen). For (c), matric potential () = –100 cm H₂O data are plotted in both normal (left axis) and log scale (right axis). ₁₀₀ = air-filled porosity at  = –100 cm H₂O; D_p,100/D₀ = soil-gas diffusivity at  = –100 cm H₂O.