title: A review of nitrous oxide mitigation by farm nitrogen management in temperate grassland-based agriculture.
abstract: Nitrous oxide (N2O) emission from grassland-based agriculture is an important source of atmospheric N2O. It is hence crucial to explore various solutions including farm nitrogen (N) management to mitigate N2O emissions without sacrificing farm profitability and food supply. This paper reviews major N management practices to lower N2O emission from grassland-based agriculture. Restricted grazing by reducing grazing time is an effective way to decrease N2O emissions from excreta patches. Balancing the protein-to-energy ratios in the diets of ruminants can also decrease N2O emissions from excreta patches. Among the managements of synthetic fertilizer N application, only adjusting fertilizer N rate and slow-released fertilizers are proven to be effective in lowering N2O emissions. Use of bedding materials may increase N2O emissions from animal houses. Manure storage as slurry, manipulating slurry pH to values lower than 6 and storage as solid manure under anaerobic conditions help to reduce N2O emissions during manure storage stage. For manure land application, N2O emissions can be mitigated by reducing manure N inputs to levels that satisfy grass needs. Use of nitrification inhibitors can substantially lower N2O emissions associated with applications of fertilizers and manures and from urine patches. N2O emissions from legume based grasslands are generally lower than fertilizer-based systems. In conclusion, effective measures should be taken at each step during N flow or combined options should be used in order to mitigate N2O emission at the farm level.
authors.affiliation: Key Laboratory of Agro-ecological Processes in Subtropical Region, Institute of Subtropical Agriculture, Chinese Academy of Sciences, Changsha, Hunan, China. dejunl@gmail.com
authors.forename: Dejun
authors.initials: D
authors.lastname: Li
authors.forename: Catherine J
authors.initials: CJ
authors.lastname: Watson
authors.forename: Ming Jia
authors.initials: MJ
authors.lastname: Yan
authors.forename: Stan
authors.initials: S
authors.lastname: Lalor
authors.forename: Rashid
authors.initials: R
authors.lastname: Rafique
authors.forename: Bernard
authors.initials: B
authors.lastname: Hyde
authors.forename: Gary
authors.initials: G
authors.lastname: Lanigan
authors.forename: Karl G
authors.initials: KG
authors.lastname: Richards
authors.forename: Nicholas M
authors.initials: NM
authors.lastname: Holden
authors.forename: James
authors.initials: J
authors.lastname: Humphreys
mesh_terms: D000383:Agriculture / Q000379:methods*; D000818:Animals; D002980:Climate; D005308:Fertilizers; D017752:Greenhouse Effect; D060434:Herbivory; D006799:Housing, Animal; D006863:Hydrogen-Ion Concentration; D058751:Livestock; D008372:Manure; D009584:Nitrogen; D009609:Nitrous Oxide; D006109:Poaceae
chemical_list: D005308:Fertilizers; D008372:Manure; D009609:Nitrous Oxide; D009584:Nitrogen
keywords: Mitigation options; N management; Nitrous oxide; Temperate grassland