Fig. 3. Comparison of the Buckingham–Burdine–Campbell (Eq. [5]) and the three-porosity model (Eq. [12] and [14]) gas diffusivity models with measured data for (a–g) seven Yellow soil layers from Japan, (h–m) 10 Latosol layers from Brazil, and (n–p) three Dutch soils (Freijer, 1994). Values of Campbell b for each soil are given. Values of ₁₀₀ are given or can be found from Table 1 (as total porosity minus soil–water content at pF 2). In (h–m) the open triangles denote compost-amended soil. UDP: Ultra-deep plowed, NP: Normal plowed.