Evaluation of soil pore-water salinity using a Decagon GS3 sensor in saline-alkali reclaimed tidal lands

This study develops general equations to extend the applications of a GS3 salinity sensor to a wide range of soils including critical saline-alkali reclaimed tidal lands. The GS3 sensor measures volumetric water content, temperature, and electrical conductivity independently. As a result of laboratory-based sensor calibration testing, it was determined that the electrical conductivity of soil pore-water solution (EC_p) with slight to moderate salinity can be computed from the bulk EC (EC_b) without calibration. The EC_b data obtained from the sensors were reconstructed via the calibration equation. We compared these results to EC_p observed from suction cup samples. A good correlation was observed between the calibrated EC_p and the observed EC_p, in low-to high-salinity soils. However, the calibrated EC_p at very high salinity underestimates the observed EC_p. Based on these results, we conclude that these sensors offer clear additional value in ensuring control of the root-zone salinity, and in compensating for weather influences.