Soil Water Retention Curve and Hydraulic Conductivity of Fungi-Treated Sand

Filamentous fungi in soil branch hyphae through pores, creating an interconnected fiber network, which is known as mycelium. Fungal mycelium can cross-link and entangle soil particles, which alters soil pore structures. Fungi can also secret hydrophobic compounds, changing the water wettability of soils. These fungal traits can affect hydraulic properties of soils. This study investigated the effect of fungi on soil water retention and hydraulic conductivity of the Ottawa 50/70 sand treated by a saprotrophic fungus, Trichoderma vixens (commonly existing in soil). Soil water retention curve (SWRC) and hydraulic conductivity tests were performed on fungi-treated and untreated Ottawa 50/70 sand. Water repellency of fungi-treated sand was also assessed by measuring contact angles (between water droplet and fungi on sand specimen) and water drop penetration time (WDPT). When compared to the untreated sand, an approximate 6-fold increase in air entry suction (S-AEV) and 2-fold reduction in hydraulic conductivity were observed in fungi-treated sand after growing fungi for 10 days. Scanning electron microscopy (SEM) imaging was conducted to assess the morphologies of sand matrix treated by fungi.