Water and Wastewater Terms Beginning S
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SAR (sodium adsorption ratio)
A ratio that expresses the relative activity of sodium ions in the exchange reactions with soil. The ratio is defined as:
SAR = NA / [1/2(Ca + Mg)]1/2
where Na, Ca, and Mg are concentrations of the respective ions in milliequivalents per liter of water.
Na [meq/L] = (Na[mg/L]) / (23.0[mg/meq])
Ca [meq/L] = (Ca[mg/L]) / (20.0[mg/meq])
Mg [meq/L] = (Mg[mg/L]) / (12.15[mg/meq])