Soil Enzyme Activity Regulates the Response of Soil C Fluxes to N Fertilization in a Temperate Cultivated Grassland

Exogenous nitrogen (N) inputs greatly change the emission and uptake of carbon dioxide (CO2) methane (CH4) from temperate grassland soils, thereby affecting (C) budget regional terrestrial ecosystems. Relevant research focused on natural grassland, but effects N fertilization C exchange fluxes different forage soils driving mechanisms were poorly understood. Here, a three-year addition experiment was conducted cultivated planted with alfalfa (Medicago sativa) bromegrass (Bromus inermis) in Inner Mongolia. The soil-atmospheric CO2 CH4; content total dissolved (TDN); organic (DON); (DOC); NH4+–N NO3−–N soil; enzyme activity; auxiliary variables (soil temperature moisture) simultaneously measured. results showed that (>75 kg ha−1 year−1) caused more serious soil acidification for planting than brome planting. stimulated P-acquiring hydrolase (AP) growing Bromus inermis did not affect C- N-acquiring hydrolases (AG, BG, CBH, BX, LAP, NAG). oxidase activities (PHO PER) higher Medicago sativa, regardless N, whether applied or not. Forage species flux, whereas high rate (150 significantly inhibited CH4 sativa. A synergistic effect between found over short term. Our findings highlight activity response to fertilization. Soil may be an important regulatory factor artificial