Stability of Soil Aggregates as Affected by Electrolyte Concentration and Composition

Stability of soil aggregates was studied under different electrolyte concentration‐sodium adsorption ratio (SAR) combinations. The extent of slaking of soil aggregates was found to depend upon the level of SAR and electrolyte concentration. At SAR 0, 10, and 20 and electrolyte concentrations above 3.2, 15.9, and 19.4 mol m −3 , respectively, slaking into aggregates as small as 5 µm occurred without or with very little clay dispersion. At lower electrolyte concentrations, clay dispersion occurred as the fine aggregates broke down into their constituents. Slaking was attributed to the shearing stresses created by an expansion of the diffuse double layers (DDL). Dispersion was initiated as the DDL on the clay surfaces expanded to the point which permitted the clay particles to separate. Clay did not disperse from the peripheries of intact soil aggregates, rather clay dispersed at the ultimate stage of the slaking process.