Relationship between SAR, wastewater quality, and soil dispersion

The electrolyte concentration of the wastewater (or, for example, irrigation water) required to prevent soil dispersion (deflocculation) is:

T S S > 0.56 (S A R) + 0.6

where TSS is Total Soluble Salts (in miliequivalents/L) and SAR is the Sodium Absorption Ratio, which here can be simplified to $N a / \sqrt{C a}$ by assuming that Mg behaves similarly to Ca.

Trench

In Trench, TSS is converted to approximate TDS (Total Dissolved Solids) by multiplying by 65, assuming that 1 milliequivalent/L is the same as 65 mg/L. The TDS thus calculated should be regarded as a guide only.

The relationship is discussed in Hart. B. T. (1974). A Compilation of Australian Water Quality Criteria. AWRC Technical Paper NO. 7 (Appendix F, pp 290-291).

Relationship between SAR, wastewater quality, and soil dispersion ​

Relationship between SAR, wastewater quality, and soil dispersion