Use of a fractal model for determining soil water retention curves

In the light of the practical application of deducing soil water retention theta(h) and hydraulic conductivity functions K(theta) from some simply determined physical properties, due consideration was given to physico-empirical models in the literature based on the transformation of particle-size distribution into a retention curve. In particular, forecasting potentials were evaluated with regard to a fractal model proposed by Tyler and Wheatcraft, relative to 25 soils occurring in Southern Italy. The estimated water retention curves show good reliability only in the case of sandy-loam and loamy soils. The lack of perfect agreement between measured and calculated theta(h) function of clayey-structured soils suggests that the particle-size distributions alone do not contain an exhaustive information needed to define the water retention function. (C) 1998 Elsevier Science B.V. All rights reserved.