Soil characteristics is very important in water erosion processes. The present investigation was conducted in gully lands of Ardebil Province, Iran, to assess the role of soil texture and structure on aggregate stability using wet sieve method. To achieve the study purposes, mean weighted diameter of aggregates was calculated, and its relationships with lime and clay percentages, sodium absorption ratio and soil organic matter were then determined. The research results showed, in the first and second depth, the organic matter had the highest direct and positive effect on aggregate stability. In first depth, clay and lime had a direct and positive effect on aggregate stability. In both depths, sodium absorption ratio had the highest but negative effect on aggregate stability. Organic matter and clay had the highest direct and positive effect on aggregate stability in the second depth. The highest indirect effect of the parameters on aggregate stability was in second depth due to effect of clay and organic matter on each other. In second depth, lime had the direct and positive effect on aggregate stability. Sodium absorption ratio had a direct and negative effect on aggregate stability in both study depths.
