محمد را مصدقی

Soil structure is a key factor in soil functioning and its ability to moderate environmental quality. Aggregate stability is used as an indicator of soil structure. The objective of this study was to determine the most important factors affecting topsoil aggregate stability in Isfahan Province. Based on the geological map, 252 soil samples were collected from the 0–20 cm depth on a 20×20 km network. Stability of large aggregates was measured using the wet-sieving method, and mean weight diameter (MWD), geometric mean diameter (GMD) and percent of water-stable aggregates (WSA) were calculated. Some soil physical and chemical properties including texture, organic matter, carbonates, gypsum, pH, EC and SAR were also determined. The impacts of different properties on aggregate stability were evaluated using correlation and stepwise multiple linear regression analyses. Results showed that the highest correlations belonged to GMD, indicating aggregate-size distribution was predominantly log-normal in the studied soils. The correlation analysis showed that gypsum content has a significant influence on aggregate stability, whereas EC, SAR and silt content are among the important soil properties negatively affecting soil structural stability. In general, structure of the soils in Isfahan Province is unstable and erodible when compared to soils in semi-humid and humid regions. Arid and semi-arid climate and low age of the soils (i.e., early stages of genesis) could hinder structure formation and stability in the studied soils.