Assessing Electrical Conductivity and Sodium Adsorption Ratio as Soil Salinity Indicators in Reclaimed Well Sites

Electrical conductivity (EC) and sodium adsorption ratio (SAR) are the two most widely used indicators of soil salinity worldwide. However, concerns regarding the use of EC and SAR for assessing soil salinity have been raised by industry, scientists, and regulators. This study examines 22 well sites across two ecoregions, sampling soils from 0 to 1.5 m depths, and hypothesized that EC and SAR may be insufficient indicators of soil salinity during reclamation. Both ecoregions had distinct soil salinity profiles, with greater variability in the upper 0.3 m. Across ecoregions, EC was 1.0–8.4 dSm−1 and SAR was 0.7–9.1. In the dry mixed-grass ecoregion, EC was moderately correlated with SAR from 0 to 0.45 m depths and significantly correlated with all ions above 0.6 m. EC explained 44–56% of chloride variation and up to 51% of sulfate in topsoil. In central parkland, EC correlated with chloride and magnesium at all depths and with calcium at most depths. SAR was strongly correlated with sodium at all depths in both ecoregions, explaining 6–82% of variation, and poorly predicted chloride and sulfate. SAR and EC did not always represent potentially toxic sodium, chloride, and sulfate ions; thus, these ions could be included as indicators, and current reclamation criteria should be modified or interpreted differently based on ecoregions and soil depths.