Evaluation of European hydraulic pedotransfer functions for boreal agricultural soils against Finnish data

Abstract

Soil hydraulic properties are essential information for sustainable agriculture and environmental management, yet their measurement is time-consuming and costly. Pedotransfer functions (PTFs) are widely used to estimate these properties from basic soil data, but few have been developed or validated for boreal conditions. This study evaluated two sets of European PTFs for boreal arable soils using a Finnish dataset of 800 water retention curves (5530 measurements) and 293 saturated hydraulic conductivity (Ksat) measurements. To assess PTF performance in modelling context, a functional evaluation with HYDRUS-1D was conducted for clayey fields, comparing simulations using measured and PTF-predicted water retention data. Performance of PTFs was reasonable in terms of water retention (RMSE 0.07–0.09 cm³ cm⁻³ and R2 0.63–0.79) and functional evaluation (R2 0.56–0.97). These results were comparable to previous studies, indicating suitability for boreal arable soils. A hierarchy of PTF performance is provided to guide their selection, while highlighting the importance of considering soil texture in their application. Ksat PTFs performed poorly and systematically underestimated measured values (R2 -2.17 – -0.86), which highlights the demand for further development before reliable application to boreal soils.