Arbuscular mycorrhizal fungi richness reduces soil N 2 O emissions while increasing maize grain nitrogen uptake

Arbuscular mycorrhizal fungi (AMF) can improve plant nutrient uptake, especially nitrogen, which may affect soil nitrogen cycling and nitrous oxide (N₂O) emission. However, little is known about how different AMF species or their richness may influence the production of N₂O, a greenhouse gas. Three AMF species were selected in this study: Funneliformis mosseae, Acaulospora scrobiculata, and Gigaspora margarita, and eight treatments were used to determine the effect of each AMF species and combinations of AMF species on soil N₂O emission. Maize (Zea mays L.) was used as a host plant. The results showed that AMF inoculants alone and in combination increased maize root length, root surface area, grain yield, and nitrogen uptake compared to the uninoculated control (without AMF), and simultaneously reducing soil N₂O emission. Soil N₂O emission declined with increasing AMF species richness, but there was no difference in maize nitrogen uptake between mixtures of two or three AMF species. The presence of multiple AMF species also reduced the relative abundance of Sphingomonadales, revealing that AMF species richness influences bacterial community composition. Taken together, soil N₂O emission was negatively related to maize root surface area, root volume, root weight, and plant nitrogen uptake, but positively related to the abundance of Sphingomonadales. These results suggest that the presence of different AMF species could reduce N₂O emission by regulating plant nitrogen uptake and soil bacteria composition, having vital implications in the field of restoration ecology and mycorrhizal technology.