Estimating soil water suction from texture, bulk density and electrical resistivity

• Published in: Geoderma Vol. 409; p. 115630
• Main Authors: Liu, Lin, Lu, Yili, Fu, Yongwei, Horton, Robert, Ren, Tusheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.03.2022
• Subjects: Formation factor; Soil electrical resistivity; Soil water retention curves; Soil water suction; Soil electrical resistivity; Formation factor; Soil water suction; Soil water retention curves
• ISSN: 0016-7061; 1872-6259
• DOI: 10.1016/j.geoderma.2021.115630

•Soil electrical resistivity (ρ) and water suction (h) depend on texture, porosity and water content (θ).•A model was developed to estimate h lower than air entry value from measured θ and ρ values.•The two model parameters are linearly related to soil texture and porosity.•The model was validated against laboratory and field measurements. Information on soil water suction (h) is essential to study water flow and solute transport in soils, and to understand engineering behaviors of unsaturated soils. Due to limited availability of field methods that can accurately measure h, numerous studies have been performed to estimate h from more readily available soil properties. In this study, a new relationship between h and soil electrical resistivity (ρ), developed from the Gardner water retention model and Archie’s second law, was used to estimate h values lower than the air entry value and a formation factor (expressed on log-scale) less than 1. The two model parameters (A and B), which are functions of soil texture and bulk density, were obtained by fitting the model to ρ and h data measured on soil columns of eight textures and various bulk densities. Laboratory and field evaluations with independent h and ρ data showed that the model estimated h values agreed well with the measured values, with root mean square errors less than 0.85 kPa. The model provides a new opportunity to evaluate in situ h dynamics and study coupled transport of water and solutes in the field.