Effects of Gully Erosion on Soil Quality Indices in Northwestern Iran

Gully erosion affects soil properties in different ways. One of the most important effects of gully erosion is destruction of soil structure and reducing its quality. The objective of this research was to study the effects of gully development on soil properties and quality indices in areas adjacent to the gullies. For this purpose, 15 soil properties and 5 soil quality indices including Integrated Quality Index (IQI), Nemero Quality Index (NQI), Cumulative Rating (CR), and Sustainability Index (SI) were compared between gully wall and outside gully lands in three sites of Ardabil province, northwestern Iran. T-test method with three replications was used for comparison. The results showed that in all three sites, 8 out of 15 soil properties changed near the gully walls, mainly indicating the reduction of soil structure, organic carbon, and S index (slope of retention curve at inflection point) and increasing the Cation Ratio Of soil Structural Stability (CROSS) and soil erodibility index. Also, near the gullies, most of the soil quality indices decreased due to gully development in the study sites. Therefore, gully formation and development in these sites reduced soil quality near the gully walls.