Which formula correctly represents the calculation of the Sodium Absorption Ratio (SAR)?

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SAR = Na / sqrt(Ca + Mg) × 2SAR = (Na / Cation Exchange Capacity) × 100SAR = Sodium divided by CEC multiplied by 100No correct formula listedNot applicable

Explanation

The Sodium Absorption Ratio (SAR) is calculated using the formula SAR = Na / sqrt(Ca + Mg) × 2, where Na, Ca, and Mg are the concentrations of sodium, calcium, and magnesium respectively. This formula helps assess the sodium hazard in irrigation water. Other options incorrectly use Cation Exchange Capacity (CEC) or are invalid.