Scaling the saturated hydraulic conductivity of a vertic ustorthens soil under conventional and minimum tillage

With the aim of setting up a simplified method to measure hydraulic conductivity of structured soils at saturation, a method reported by Ahuja at al. (Soil Sci. Sec. Amer. J. 48 (1984) 699-702; Soil Sci. 148 (1989) 404-411), which also refers to the generalised equation of Kozeny-Carman and the scaling theory, is tested in this paper. Data were elaborated from hydraulic conductivity measurements K-s on undisturbed soil cores taken from three plots of a sloping vertic soil which underwent various tillage practices for many years. In particular, following the proposed methodology, the spatial distribution effective soil porosity phi was first obtained. Once the distributions of hydraulic conductivity at saturation were obtained, it was possible to correlate the spatial variability of hydraulic conductivity with the variability of the unique factor a scaled by effective soil porosity. Statistical elaboration indicated that the log-normal law is the one which best approximates the frequency distribution of scale factors alpha(k) and alpha(phi). No significant differentiations were noted between the distributions of parameters relative to different soil tillage systems. (C) 2000 Elsevier Science B.V. All rights reserved.