Evaluating the influence of fungal growth on soil water repellency and soil aggregation for biogeotechnical slope stabilisation applications

Many slope failures globally are triggered by heavy rainfall, and the corresponding loss in shear strength as water infiltrates into initially partially saturated slopes. Here, we explore the potential use of saprotrophic fungi, in particular Pleurotus ostreatus (P. ostreatus) for biogeotechnical slope stabilisation. P. ostreatus has been previously shown to enhance water repellency, reduce water infiltration and hydraulic conductivity and improve resistance to erosion in sterile sands (Salifu, 2019; Salifu and El Mountassir, 2021; Salifu et al, 2022). Such modifications to soil behaviour could be beneficial in the treatment of granular slopes, to reduce water infiltration and thus enhance runoff without enhancing soil erosion.

In this study we investigated P. ostreatus growth in soils that were initially sterile and non-sterile to understand the influence of the pre-existing microbial community. Three soils were investigated compost, sand and a silty clay. P. ostreatus growth and its influence on water repellency and aggregate size distribution was measured over an 8 day period. Our results for the silty-clay indicate that it is possible for P. ostreatus growth to occur in non-sterile soil, with corresponding desirable modifications to soil properties, and at a similar level of modification to that achieved in sterile conditions, even within the short timeframe of this study (8 days).