THE EFFECTS OF SODIUM ADSORPTION RATIO AND ELECTROLYTE CONCENTRATION ON WATER-QUALITY - LABORATORY STUDIES

The effects of solution sodium adsorption ratio (SAR) and total electrolyte concentration (TEC) on the release of total organic carbon (TOC), total N and total P, and clay dispersion from three soils were studied in the laboratory. Solutions with high SARs and low TECs caused the greatest amount of clay dispersion, and these highly turbid solutions also had high concentrations of TOC and total P. Positive correlations were obtained between turbidity and TOC, turbidity and total P, and TOC and total P. Total N was positively correlated with turbidity and TOC for one of the soils studied, but not for the other soil for which these measurements were made. It follows from these results that SAR and TEC also have a significant influence on TOC and total P concentrations. Field data of other workers show similar relationships between these water quality factors. Decreasing the SAR and/or increasing the TEC of a solution in contact with soil will decrease the concentrations of organic carbon and total P released and decrease clay dispersion. For some soils, the concentration of N in solution may also decrease. Increasing salt concentrations substantially is not desirable, but a decrease in SAR can be achieved through the use of calcium compounds and their application to soils in a field situation may help to improve water quality.