Organic carbon loss and sediment enrichment during interrill erosion influenced by simultaneous wind and rain

Interrill erosion is one of the most important types of erosion in agricultural lands, causing organic carbon (OC) loss from the soil surface. However, soil OC deficiency is a challenge facing agricultural production in most arid and semi-arid regions of Iran. In these regions, rainfall may be associated with high-speed winds that may remove large amounts of soil and OC. Therefore, the present study was carried out to investigate the role of wind and rain as erosive factors on the soil and OC losses and sediment enrichment during erosion events in some contrasting soils. For this purpose, using a simultaneous wind and rain simulator, combinations of three rain intensities (20, 40 and 60 mm h-1) and four wind speeds (0, 6, 9 and 12 m s-1) were introduced on three soils (sandy, sandy loam, and loam), each at three replicates. The results showed that the OC loss from the soils changed from 0.04 to 4.04 mg m-1 s-1. Synergistic interaction between rain and wind on OC loss was detected. In addition, a threshold limit (9 m s-1) was observed for wind velocity, above which soil and OC losses increased sharply. On the other hand, with increasing soil loss, the OC loss from each soil increased linearly. The contribution of OC loss in the total soil loss for sandy, sandy loam and loam soils was 0.36, 0.17 and 2.19%, respectively. Moreover, the enrichment ratio of OC in the sediments of soils was 8.2, 1.01 and 12.2, respectively. Based on the findings of this study, the wind speed reduction is recommended in agricultural lands, especially in windy areas to control the losses of OC due to interrill erosion.