Learn about salinity and related concepts

Learn about salinity and water quality

Chart: SAR vs. EC from Ayers and Westcot

Chart using SAR and EC together to assess an irrigation water

Advanced topics in water chemistry and salinity

Using both ECw and SAR to evaluate a water

The tendency of an elevated sodium concentration in a water to cause dispersion of soil particles, impairing the soil's permeability, is counteracted somewhat by a high electrolyte concentration — high salinity. Because of this counteractive effect, one must consider a water's total salinity when assessing the water's potential sodium hazard.

The best way to do this is to evaluate two parameters at once: the water's SAR, together with the water's ECw. The diagram below provides a useful guideline for assessing a water and determining what level of reduction in soil permeability, if any, is likely to occur.