Hydraulic behaviour of fungal treated sand

Engineered growth of the saprotrophic fungus Pleurotus ostreatus has recently been observed to induce water repellency in sands. As such, there is potential for the deployment of fungi to reduce water infiltration in granular soils. In this study, we investigate the influence of the growth of P. ostreatus on the hydraulic behaviour of a sand amended with organic matter (lignocellulose) over a 12-week period. This includes investigation of the water retention and quasi-saturated hydraulic conductivity properties and the response to ponded infiltration. Furthermore, we investigate alterations to soil microstructure due to fungal growth using X-ray micro-computed tomography. Fungal treatment resulted in a shift in the wetting curves to lower suctions and drying curves to higher suctions, lower quasi-saturated hydraulic conductivity, and lower ponded infiltration rates. These alterations to the hydraulic behaviour are attributed to combined biochemical and biophysical effects of fungal growth leading to clogging of some soil pores by fungal hyphal biomass. These results illustrate the potential for the deployment of fungal treatment as a low-cost technology suitable for application at catchment-scale which could be used to enhance the stability of shallow slopes, cut slopes and retaining walls by maintaining higher soil suction and shear strength after rainfall events.