Changeability of rill erosion properties due to microorganism inoculation

Abstract

This study aimed to assess the impacts of using soil microorganisms onrill erosion prosses. Consequently, the efficacy of individual bacteria (Ba) and combined inoculation of bacteria and cyanobacteria (Ba + Cy) extracted from a Marl region's soil microorganism bank in changing rill erosion processes was investigated. The experiment was carried out on mid-sized plots (1 × 6 m) with a 30 % slope and three replicates. Plots were subjected to a design simulated rain with an intensity of 50 mm.h−1 and a duration of 30 min. A supplementary runoff with a discharge of 2 L.min−1 was also used to mimic more extended slope conditions to motivate the rilling phenomenon. The results of the study disclosed that the control (i.e., not inoculated) and treated plots (i.e., Ba and Ba + Cy) behaved differently in the viewpoint of runoff, soil loss, flow hydraulics, and rill morphometry. Statistical analyses revealed that Ba and Ba + Cy treatments controlled all runoff and soil loss components, flow hydraulic characteristics, and rill morphologic factors significantly (p < 0.05) except the infiltrated water (p = 0.56) and the Froude number (p = 0.11) compared to the control plots. The findings implied that Ba and Ba + Cy inoculations, compared to control plots, increased infiltrated water by 1.73 and 1.55 folds and reduced soil loss by 100.31 and 273.94 folds, respectively. The Froude and Reynolds numbers declined by 2.34 and 5.77 folds when Ba was applied. At the same time, Ba + Cy decreased the Froude and Reynolds numbers by 1.24 and 20.08 folds, respectively. Furthermore, rill frequencies in the treated plots by Ba and Ba + Cy were tobogganed by 3.67 and 2.20 folds with a high effect on increasing initiation times by 17.80 and 28.29 folds compared to the control treatment. Our findings suggest endemic microorganism inoculation as an effective bioengineering technique for managing rill erosion-prone regions.