Runoff and soil loss from small plots of erosion-prone marl soil inoculated with bacteria and cyanobacteria under real conditions

Abstract

Land degradation is a major global concern that is exacerbated in the erosion-prone marl and calcium carbonate-rich mudstone slopes. Several studies have therefore focused on finding ways to inhibit soil erosion among which, soil inoculation has been recently introduced as a new technique. However, the success of such treatment has not been adequately taken into account. Following this, in this study, we assessed the hydrological responses of an erosion-prone marl soil due to surface inoculation of bacteria and cyanobacteria. The individual bacteria and cyanobacteria and their combination were inoculated (in three repetitions) on 0.5 m × 0.5 m-sized plots filled by marl soil from the Marzanabad Region in the north of Iran. The entire plots were thoroughly exposed to natural conditions in an open area at the campus of Faculty of Natural Resources of Tarbiat Modares University in Noor, Mazandaran Province, Iran. After 32 days of inoculation, five erosive natural rainfalls occurred on the experimental plots, from 10 to Jan. 29, 2018. The rainfalls on control plot led to a relatively high runoff yield (i.e., 223–2010 ml) and coefficient (i.e., 2.3–7.6%), a considerable soil loss (i.e., 1.32–17.96 g), and sediment concentration (i.e., 2.4–9 g l−1). Whilst, in the inoculated (i.e., bacteria, cyanobacteria, and bacteria + cyanobacteria) plots, the runoff volume, runoff coefficient, soil loss, and sediment concentration varied between 56 and 1116 ml, 2.3–9.4%, 0.16–4.04 g, and 1.01–3.61 g l−1, respectively. It, therefore, verified that the soil inoculation decreased the runoff yield and coefficient (29–77%), soil loss (77–89%), and sediment concentration (60–76%), as compared to the control. On the whole, we found that the soil inoculation technique could be considered as a bio-strategy to conserve/restore marl soil lands, where the viability of conventional methods is low.