Fig. 7. Test of Eq. [6] to predict gas diffusivity (D_P,100/D₀) at -100 cm H₂O of matric potential, ₁₀₀ = macroporosity. Data for 18 undisturbed Andisols and four undisturbed Gray-lowland soils. Solid line is Eq. [6]. Dotted lines are 95% prediction interval obtained when applying Eq. [6] to data for 144 undisturbed European soils (Moldrup et al., 2001).