A novel method to improve the soil erosion resistance with fungi

This study evaluated an innovative method to improve soil erosion resistance by fungi. An edible filamentous fungus, Pleurotus ostreatus, was included in the study. The result showed that Pleurotus ostreatus is able to grow and completely cover the circular surface of 60.20 mm diameter in 15 days when inoculated on the top surface and in 20 days when inoculated 5 mm under the soil surface. The erosion resistance of fungi mediated soil samples was evaluated by a Simplified Scour Resistance Test (SSRT). The results showed that fungi-mediated sand samples demonstrated much higher erosion resistance compared with control sand sample, both in terms of increasing the critical flow velocity and reducing the slope of erosion rate versus flow velocity curve. The mechanism of improved erosion resistance was investigated. The microstructure measured by SEM test showed that the sand particles were entangled by fungal fibers. Chemical precipitations were observed on sand surface and attached to fungal hyphae, which were identified as calcite, calcium oxalate monohydrate and calcium oxalate dihydrate by FTIR spectra and XRD analysis. The fungi mycelium surface showed hydrophobic behaviors with an average measured contact angle of 116.42°. The hydrophobicity generated slip along the interface. Analyses with computational fluid dynamics (CFD) model indicated that the slip due to the hydrophobicity of fungi reduced the shear stress at the water-soil interface, which also improved the erosion resistance by fungi-mediated sand.