Soil erosion versus soil retention capacity: an impact assessment of regulating ecosystem service provision in Iran

The objective of this study was to determine the impact of erosion on soil retention as an ecosystem service and its relationship with soil quality in a mountainous catchment in Iran. In this regard, 42 soil samples were collected from rangelands, rainfed, and irrigated farming. Thirteen physical and chemical soil attributes were measured. Principal component analysis was applied to identify a soil quality index (SQI). The respective ranges of soil erosion rates from rangelands, rainfed farming lands, and irrigated farming lands were estimated to be 0.2 – 46.4, 0.18 – 0.20, and 0.00 – 0.18 t ha−1 yr−1. The SQI estimates ranged between 3.2 – 4.0 for the rangelands compared with corresponding respective estimates of 4.0 – 5.7 for the rainfed farming lands and 5.7 – 8.4 for the irrigated farming lands. Soil retention was estimated to range between 0 – 0.01 t ha−1 yr−1 (average = 0.005 t ha−1 yr−1) for rangelands, 0.01 – 0.03 t ha−1 yr−1 (average = 0.02 t ha−1 yr−1) for rainfed farmlands, and 0.03 – 3.5 t ha−1 yr−1 (average = 1.8 t ha−1 yr−1) for irrigated farming lands. Negative relationships were observed among soil erosion, soil quality, and soil retention emphasizing the sensitivity of soil quality to the soil erosion rates estimated for different land use types. This study provides evidence for the negative effects of soil erosion under different land uses regarding the degradation of soil quality and soil retention as an ecosystem service.