Technical note: Saturated hydraulic conductivity and textural heterogeneity of soils

Abstract

Saturated hydraulic conductivity (Ksat) is an important soil parameter that highly depends on soil's particle size distribution (PSD). The nature of this dependency is explored in this work in two ways, (1) by using the information entropy as a heterogeneity parameter of the PSD and (2) using descriptions of PSD in forms of textural triplets, different than the usual description in terms of the triplet of sand, silt, and clay contents. The power of this parameter, as a descriptor of ln Ksat, was tested on a database larger than 19 000 soils. Bootstrap analysis yielded coefficients of determination of up to 0.977 for ln Ksat using a triplet that combines very coarse, coarse, medium, and fine sand as coarse particles; very fine sand, and silt as intermediate particles; and clay as fine particles. The power of the correlation was analysed for different textural classes and different triplets using a bootstrap approach. Also, it is noteworthy that soils with finer textures had worse correlations, as their hydraulic properties are not solely dependent on soil PSD.This heterogeneity parameter can lead to new descriptions of soil PSD, other than the usual clay, silt, and sand, that can describe better different soil physical properties, that are texture-dependent.