Reversibility of Saturated Hydraulic Conductivity under Soil Sodicity and High Electrolyte Concentration

Abstract

We investigated the effect of sodicity on the reversibility of saturated hydraulic conductivity (Ks) under high electrolyte concentration (HEC) EC ≥16 dS/m. This laboratory investigation consisted of measurment of Ks using the permeameter of McNeal and Reeve (1964) by varying sodicity. We increased sodicity, expressed by Sodium Adsorption Ratio (SAR), in steps from a min of 0 to a max of 30, and then we followed the same procedure, but then backwards. Measurement of soil dispersion was carried out for all the SAR values used in the measurement of Ks using the method of Velasco-Molina et al. (1971). Under HEC Ks decreased as sodium adsorption ratio (SAR) increased. SAR increment of +/- 15 causes the most important decrease. However, when decreasing the SAR again, Ks does not show an increase, it is irreversible for these conditions of experimentation.In contrast; soil dispersion (SD) shows an increase with increasing SAR, but then also decreases again when SAR is lowered. This decrease is not sufficient to compensate the irreversibility of Ks.

Keywords

• saturated hydraulic conductivity
• reversibility
• sar
• dispersion
• electrical conductivity