The effect of exclosure management on the reduction of SOC loss due to splash erosion in gypsiferous soils in Southwestern Iran

An understanding of the effect of exclosure on soil organic carbon (SOC) content changes and its loss due to soil erosion in arid and semi-arid rangelands is essential to the establishment of stable ecosystem conditions. The aim of this study is to investigate the loss of SOC during natural rainfall due to splashed particles of gypsiferous soils. Accordingly, a three-factor factorial experiment is performed within a completely randomized design with a splash cup under natural rainfall over three replications. The first factor is exclosure at two levels (exclosure and non-exclosure); the second factor is rainfall erosivity factor at three levels (EI30: 1153.5, 4307.6, and 7714 J m− 2 cm− 1); and the third factor is slope percent at three levels (0%, 5%, and 15%). The results showed that exclosure had a significant impact on soil splash erosion rate in terms of upslope splash erosion (USE), downslope splash erosion (DSE), total splash erosion (TSE), and loss of SOC. In non-exclosure conditions, the USE, DSE, and TSE increased by 32.4%, 13.5%, and 17.8%, respectively, compared to exclosure conditions. The amount of organic carbon lost due to splash in non-exclosure conditions was 1.29 times higher than in exclosure conditions. In addition, by increasing the slope and the rainfall erosivity index, a significant reduction was observed in USE and a significant increase was observed in TSE, DSE, and the loss of SOC. As a result of increasing the index EI30 from 1153.5 to 4307.6, the loss of SOC increased by a factor of 1.3, and as a result of increasing the rainfall erosivity index (EI30) from 1153.5 to 7714, the loss of SOC increased by a factor of 1.4. Organic carbon loss in the slope of 0-5% was approximately 0.061%, and by increasing the slope to 5-15%, and then 15-30%, carbon loss increased by factors of 1.5 and 1.34, respectively. Therefore, the exclosure treatment had a significant impact on reducing soil and organic carbon loss in the fields. It seems necessary, therefore, to consider exclosure treatment as a major part of renewable natural resources projects, especially in watershed management plans involving the gypsiferous soils of Iran.