Analysis of pedotransfer functions to predict the effects of salinity and sodicity on saturated hydraulic conductivity of soils

Abstract

Soil sodicity and salinity are global issues associated with irrigated and non-irrigated land management. The combination of high sodium adsorption ratio (SAR) and low electrical conductivity (EC) of the soil solution decreases the saturated hydraulic conductivity of soils. Unfortunately, there have been few attempts to model the changes in saturated hydraulic conductivity in response to EC and SAR. The objectives of this study was to analyze previously developed functions to predict changes in saturated hydraulic conductivity (Ksat) with EC and SAR and to develop new simple functions to predict changes in Ksat with EC and SAR. The performance of previously developed functions were analyzed on 10 different soils. New pedotransfer functions (PTFs) were developed to predict the effects of EC and SAR on relative saturated hydraulic conductivity. The developed PTFs were able to predict the changes in relative Ksat with a geometric root mean squared error (GMRMSE) of 1.80 compared to 3.38 cm day−1 from the semiempirical function used as a module implemented by the Hydrus hydrological modeling application. A PTF was developed to predict the change in relative saturated hydraulic conductivity in soils with swelling clay minerals that does not require X-ray diffraction to quantify clay mineralogy and has the same prediction parameters used for every soil. The developed PTF can easily be used by agricultural and irrigation managers to predict the effects of irrigation water chemistry on relative saturated hydraulic conductivity.