Soil N cycling processes in a pasture after the cessation of grazing and CO2 enrichment

摘要: Abstract The effect of elevated CO2 (eCO2) on nitrous oxide (N2O) emissions is important as it could negate some the potential benefits eCO2 carbon sink activity and thus affect concentration greenhouse gases in atmosphere. Grazed grassland a significant source N2O but no studies have so far measured effects processes related to production grazed by animals. Here we examine microbial functional genes that had received 14 years enrichment. measurements were made 18 months after enrichment was stopped areas allowed us distinguish between grazing with without return animal excreta. Our results showed excreta compared soil pH, positive total nitrogen (TN), NO3− concentration, nosZ (nitrous reductase) gene abundance, NEA/DEA (nitrifying enzyme activity/denitrifying activity). Elevated significantly increased NH4+ abundance (in area where returned) reduced NEA ANEA (autotrophic nitrifying enzymes) DEAN2 (the flux N2 from denitrification). In addition, HNEA (heterotrophic activity) only evident under eCO2. These responses indicate long-term promoting production.