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  Sodium Adsorption Ratio advert image shown if present

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A measure of the concentration of sodium and its relationship with calcium and magnesium in irrigation, especially extracted from bore holes or from recycled water, or soil water to determine soil or water salinity. The SAR value is the ratio of the amount of sodium (measured in meq/L) divided by the square root of one-half of the amount of calcium and magnesium.
SAR=〖Na〗^+/√((〖Ca〗^(+2)+ 〖Mg〗^(+2))/2)

The hazard presented from the water will depend not just on the SAR value but also the value of the electrical conductivity of the water.