Fig. 5. Log-transformed air permeability at matric potential of –100 cm H₂O [log(k_a,100)] as a function of air-filled porosity at matric potential of –100 cm H₂O (₁₀₀) for lysimeter soils and field soils (shallow and deep soil layers). Estimated and regression curves for k_a,100 (Eq. [12] with equivalent pore diameter for gas flow estimated by Eq. [10] = 150 µm and Eq. [13]) are given.