Majid Mahmoodabadi; Samira Zamani; Najme Yazdanpanah
Abstract
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 ...
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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.
Aghdas Sotoudehnia; Majid Mahmoodabadi; Majid Fekri
Abstract
Due to low plant cover in arid and semi-arid regions, surface gravel cover (SGC) plays an important role in soil erosion control. The aim of this study is to investigate the effect of SGC and slope gradient on splash as well as interrill erosion in two contrasting soils. For this purpose, a constant ...
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Due to low plant cover in arid and semi-arid regions, surface gravel cover (SGC) plays an important role in soil erosion control. The aim of this study is to investigate the effect of SGC and slope gradient on splash as well as interrill erosion in two contrasting soils. For this purpose, a constant rain was simulated on two soils namely sandy and cropland with different aggregate size distributions at four slope gradients including 0.5, 2, 5 and 10 % and five levels of SGC including 0, 5, 10, 20 and 40 % each at three replicates. Through producing a rain intensity of 35 mm/h for 35 min duration on a 0.35 m by 0.35 m test area, both splash (downward, upward and the total splashed material) and interrill erosion rates were measured. Result showed that with increasing SGC in both soils, the downward, upward and the total average splash increased, significantly. However, the downward splash rate was higher than the upward splash rate. With increasing SGC from 0% (control) to 5, 10, 20 and 40 %, the downward splash rate decreased for the sandy soil by 12.9%, 25.3%, 35.7% and 47.7%, and for the cropland soil by 13.9%, 25.4%, 37.0% and 49.4%, respectively. Regarding the interrill erosion rate, the corresponding reduction percentages for the sandy soil were 13.5%, 26.4%, 33.3% and 46.4% and for the cropland soil were 12.9%, 30.7%, 37.3% and 45.9%, respectively. Moreover, nonlinear increases in the interrill and splash erosion rates were found at steeper slopes. Due to lower cohesion and greater detachability of sandy soil, it exhibited higher erosion rates than those for the cropland soil. The findings of this study revealed that in the presence of SGC, both splash and interrill erosion rates will reduce, significantly.
