Arbuscular mycorrhizal fungi alleviate erosion-induced soil nutrient losses in experimental agro-ecosystems

Erosion-induced nutrient losses from agricultural soils are crucial for agricultural and environmental sustainability. Arbuscular mycorrhizal (AM) fungi have the potential to enhance nutrient uptake by crops and immobilization by soil particles, and improving soil structure, which together reduce overall nutrient losses from soils. Despite their importance, the mechanism(s) by which AM fungi ameliorate erosion-induced nutrient losses have not been reported. This understanding is urgently needed for management of nutrient in agricultural systems and for ecosystem sustainability. In this study, we conducted simulated erosion experiments to determine the effects of exogenous AM fungal inoculation (Glomus mosseae) on erosion-induced soil nutrient losses, and how such effects vary with erosion intensities (light vs heavy erosion) and cropping systems (maize vs soybean). We show that AM fungal inoculation decreased the total loss of nitrogen (N) (-18.4% and -14.1% in maize and soybean, respectively) and phosphorus (P) (-27.6% and -38.8% in maize and soybean, respectively) in runoff and sediment compared to control treatments. The positive effect of AM fungal inoculation on reducing soil nutrient losses was consistent with crop systems, it increased with erosion intensity. Some of the positive effect of AM fungal inoculation on nutrient losses was likely due to enhanced plant nutrient uptake (33.1–128.2%) and decreased runoff and sediment loss (3.4–49.7%). Taken together, these results demonstrate that AM fungal inoculation significantly reduced erosion-induced soil nutrient losses, and highlight the potential of using AM fungal inoculation as a means to support sustainability of agriculture systems and other environments.