The significant contribution of fungi to soil N2O production across diverse ecosystems

Abstract Sporadic observations from pure culture study and direct soil measurement have indicated that fungi can substantially contribute to soil N 2 O production. Yet, it is still uncertain whether this fungal significance is a more general ecological phenomenon. In this study, relative contributions of fungi and bacteria to soil N 2 O production were examined in five ecosystems, including conventional farming (CON), integrated crop and livestock system (ICL), organic farming (ORG), plantation forestry (PF), and abandoned agriculture field subjected to natural succession (SUCC). Soil N 2 O production was measured at 90% water-filled pore space from antibiotic-free controls and soils amended with streptomycin, cycloheximide, or both. Streptomycin and cycloheximide additions significantly reduced soil N 2 O fluxes from the five systems, ranging from 31% to 54% and 40% to 51%, respectively. Fungi contributed more to soil N 2 O fluxes than bacteria in PF, whereas fungi and bacteria made comparable contributions in other four systems. Furthermore, soil pH was correlated positively with the percentage of bacterial contribution to soil N 2 O flux, but negatively with the percentage of fungal contribution to soil N 2 O flux as well as the ratio of fungal-to-bacterial contributions. Our results showed that fungi could potentially contribute to soil N 2 O production in diverse agroecosystems and their contribution might be more pronounced in the acidic plantation forestry.