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We investigated the stability of 34 aridzone toil samples from 15 soil series, using clay dispersion and aggregate stability as structural indexes. The study evaluated clay dispersion and aggregate stability as affected by: pH, electrical conductivity, sodium adsorption ratio, soluble silica, cation exchange capacity, exchangeable sodium percentage, inorganic carbon, organic carbon, free iron oxide, free aluminum oxide, clay, surface area, quartz, kaolinite, illite, chlorite, vermiculite, and montmorillonite. The most significant single-variable linear regressions were obtained for percentage of clay dispersed versus log (montmorillonite) (r2 = 0.52**) and for percentage of aggregate stability versus organic carbon (r2 = 0.27**). Significant variables for multiple linear regression for percentage of clay dispersed were montmorillonite, exchangeable sodium percentage, and electrical conductivity (r2 = 0.67**). For percentage of aggregate stability, significant variables in the multiple linear regression were quartz, montmorillonite, and surface area (r2 = 0.49**). Principal factor analysis results indicated that the structural indexes were related most to the soil variables stabilizing structure by physically binding particles. These binding agents are aluminum and iron oxides and organic matter.
Goldberg et al. (Tue,) studied this question.