Deriving and validating pedotransfer functions for some calcareous soils

The unsaturated soil hydraulic properties are needed for many different applications in soil hydrology. Pedotransfer functions (PTFs) have proven to be useful to indirectly estimate these parameters from more easily obtainable soil data. Until now no studies have been conducted to derive or verify PTFs for calcareous soils, which hydraulically may not behave the same as non-calcareous soils. The objectives of this study were to assess the influence of soil CaCO3 on the soil water retention characteristics of some calcareous soils, and to derive PTFs for these soils. Two data sets were used to derive and evaluate the established PTFs. Data set 1 containing 220 samples was employed as a calibration set for multiple linear regression. An independent data set containing 55 soil samples from a different location served to verify the derived PTFs. No significant difference in accuracy was found between the PTFs with and without CaCO3 in terms of estimating specific soil water retention values or the van Genuchten soil hydraulic parameters. Compared with the Rosetta PTFs of Schaap et al. (2001), the derived point and parametric PTFs provided better accuracy with average RMSE values of 0.028 and 0.107 cm(3) cm(-3), respectively. (C) 2010 Elsevier B.V. All rights reserved.