Effects of mycorrhizal Bermuda grass on low-range soil matric suction

Abstract

Soil matric suction, or negative water potential, contributes to soil physical stability (e.g., slope). Plants retain soil matric suction as they take up and transpire water in soil. This study investigated the effects of the common plant root-fungi symbiosis on the changes of the low-range matric suction (i.e., 0–100 kPa), which is relevant to slope stability. Bermuda grass (Cynodon dactylon) was grown in compacted soil (dry density ~ 1680 kg m−3) with and without the inoculation of an arbuscular mycorrhizal fungus (AMF) (Rhizophagus intraradices). Matric suction along the soil depth was measured during wetting and drying. Biomass, fungal colonization rate, and wet-aggregates size distribution were investigated subsequently. AMF association did not exert significant effects on the matric suction (range 0–80 kPa) distribution compared with the control, during wetting and drying. AMF significantly decreased the root biomass compared with the control. Significantly, higher proportions of 2–5-mm wet-aggregates were observed in the inoculated treatment than the control. AMF can hinder root growth, and the choice of plant-fungus combination should not be neglected. Higher root biomass is preferred during drying in order to achieve a higher initial suction before the rainfall. Promoting root biomass would be more essential than shoot biomass during wetting (heavy rainfall). The application of AMF should be considered for soil erosion control during the early stage of restoration works.