Measurement of soil water retention curves (SWRCs) is time consuming, and there is no single laboratory device available to measure a SWRC over an entire range of relevant pressures. The van Genuchten (vG) model is commonly used to characterize the shape of the SWRC. Bulk soil electrical conductivity as a function of water content, σ(θ), has been used to estimate hydraulic properties of unsaturated soils, thus making it possible to relate σ(θ) and SWRC. The saturated and residual water content values, θ_s and θ_r, can be estimated from soil bulk density and particle size distribution. In this study, we present an approach to estimate vG parameters m and α from σ measured at saturated and residual soil water contents, as well as σ(θ) values measured at intermediate water contents. A thermo-time domain reflectometry (thermo-TDR) sensor is used to measure σ and θ of the same soil sample volume. SWRCs for three soils (Glassil 530 sand, Tennessee silt loam and Illinois clay loam with bulk densities ranging from 1.52 to 1.67 g cm⁻³, 1.05 to 1.25 g cm⁻³ and 1.05 to 1.2 g cm⁻³, respectively) are estimated from σ(θ) measurements and compared with direct SWRC measurements obtained with a tension table and pressure plate extractors. Additional comparisons are made using data obtained from the literature. The proposed method to estimate SWRCs performs well when compared to direct SWRC measurements (with an average RMSE and an average bias of 0.041 cm³ cm⁻³ and 0.008 cm³ cm⁻³, respectively). Results indicate that the new σ(θ) based method accurately estimates SWRCs.

测量土壤保水曲线（SWRC）非常耗时，并且没有一个单独的实验室设备可在整个相关压力范围内测量SWRC。van Genuchten（vG）模型通常用于表征SWRC的形状。土体电导率随含水量σ（θ）的变化已被用于估算非饱和土的水力特性，因此可以将σ（θ）和SWRC关联起来。饱和和残余水含量值，θ_小号和θ _[R ，可从土壤堆积密度和粒度分布进行估计。在这项研究中，我们提出了一种估计vG参数m的方法在饱和和残留土壤含水量下测得的σ和在中等含水量下测得的σ（θ）值。热时域反射法（thermo-TDR）传感器用于测量相同土壤样品体积的σ和θ。对于三种土壤（Glassil 530砂，田纳西州的粉砂壤土并伊利诺伊粘壤土与堆积密度范围从1.52到1.67 SWRCs克厘米^-3，1.05至1.25克厘米^-3和1.05至1.2克厘米^-3分别由σ（θ）测量值估算，并与使用张力表和压板提取器获得的直接SWRC测量值进行比较。使用从文献中获得的数据进行其他比较。与直接SWRC测量（分别具有平均RMSE和平均偏差分别为0.041 cm ³ cm ^-3和0.008 cm ³ cm ^-3）相比，所提出的估计SWRC的方法效果很好。结果表明，新的基于σ（θ）的方法可准确估算SWRC。