Evaluation of soil salinity using the dielectric sensor WET-2

Abstract

Context The electrical conductivity of the soil saturated paste extract (ECe) is used to estimate the soil salinity. Aims This study aims to develop simple or multiple linear regression models to estimate the ECe using soil properties measured by a dielectric sensor in the field. Methods The measurements of bulk electrical conductivity (ECb), soil temperature (T) and dielectric permittivity (εb) in agricultural fields were conducted using the WET-2 sensor. A total of 105 soil samples were obtained from agricultural fields in three regions of Greece. Key results A very strong positive correlation between ECb and ECe (r > 0.6 and P < 0.001) was obtained by using the Spearman’s correlation coefficients. Multiple linear regression models (MLR) were developed using only the parameters εb, ECb and T measured by the WET-2 in estimating ECe. Considering that the MLR models are site specific, the ECe could be reliably estimated by applying MLR models in regions with coarse textured soils. Contrarily, in regions with finer textured soils characterised by ECb values <1 dS m−1, additional soil parameters are required to be included in MLR models to estimate of ECe more accurately. In regions with soils characterised by high salinity (4 dS m−1 < ECe < 25 dS m−1), a simple linear regression model seems to be sufficient. Conclusions and implications As the WET-2 sensor measures simultaneously three soil properties in situ, it might be a valuable tool for estimating ECe, for the first centimetres of soil, in the case that the soil is not dry with relatively low clay content.