Stabilizing sand from dried-up lakebeds against wind erosion by accelerating biological soil crust development

Abstract

Land degradation and the resulting desertification often lead to sand flowing from deserts and/or dried-up lakebeds and into habitable zones; a problem that has intensified in recent decades. We cultivated locally collected biological soil crust (BSC) bacteria (Bacillus subtilis strain) and cyanobacteria (Nostoc sp. and Oscillatoria sp.) from the dried-up bed of Lake Urmia, northwest Iran. To evaluate the ability of BSC to stabilize the sandy lakebed soil, bacteria and cyanobacteria were used to inoculate experimental trays of sandy soil from the same area, under laboratory conditions. After 120 days, we simulated winds at a speed of 72 km h−1 for three 10-min intervals (30 min in overall) to measure the sand transport rate as well as the durability and fragility of the BSCs during the wind erosion process, using an open circuit wind tunnel. We found that the bacteria, cyanobacteria, and cyanobacteria + bacteria inoculation reduced the sand flowing by 42.3, 96.6, and 95.9%, respectively, as compared to the control. We found that in addition to creating a protective cover on the soil surface, cyanobacteria created a strong bond between the soil particles through their exudation of exopolysaccharides and network of filaments, increasing the ability of the sand to withstand wind forces. Our inoculation technique was an effective and natural way to stabilize moving sand. Future research should replicate our methods under natural conditions to evaluate the potential for large-scale restoration.