Estimation of soil hydraulic parameters for different land-uses

Water retention capacity and saturated hydraulic conductivity are important soil hydraulic properties that affect soil productivity and the environment. The knowledge of soil water properties and land-use effects on these properties are important for efficient soil and water management. The aim of this work was to evaluate the effect of cultivation of rangelands on soil water retention. Furthermore, the use of the van Genuchten equation to estimate soil saturated water content (θs) and water content (θh) was assessed. The comparison of the parameters of this equation [water release parameters (α and n) and residual water content (θr)] obtained in cultivated and rangelands was also evaluated. Moreover, a comparison between measured and estimated soil saturated hydraulic conductivity (Ks) by several selected pedotransfer functions (PTFs) was performed. The study showed that the land-use effect on soil water retention was significant only at water potentials of −33 and 0 kPa in the top 15 cm of the soil. At the −1500 kPa pressure head, water content was not affected by the land-use type at soil depths of 0–15 cm and 15–30 cm. In this study, α, n, and θr values were not significantly different between the two land-use types. The fit of the van Genuchten model to water retention data resulted in a low sum of squared errors and high coefficient determination values. Overall, the van Genuchten equation can be used as a physically based model for soil water retention characterization in the studied area. However, this model was not able to accurately estimate Ks. No distinct trend for estimated Ks by the selected PTFs in the studied area was observed. Thus, it is essential to evaluate the model applicability for different soils at various sites. © 2016, Springer International Publishing Switzerland.