title: In-season root-zone N management for mitigating greenhouse gas emission and reactive N losses in intensive wheat production.
abstract: Although both the grain yields and environmental costs of nitrogen (N) fertilization are gaining more public and scientific debate, the complex linkages among crop productivity, N application rate, environmental footprints, and the consequences of improved N management are not well understood. We considered the concept of linking greenhouse gas (GHG) emission, reactive N losses, and N fertilizer application rates with crop productivity to determine the response of the GHG emission and reactive N losses to N surplus and further evaluated the potential to reduce these N environmental footprints by in-season root-zone N management. A meta-analysis suggested an exponential increase in the response of direct N2O emissions and nitrate leaching to an increasing N surplus, while NH3 volatilization increased linearly with an increasing N application rate for intensive wheat production in north China. The GHG emission and reactive N losses during N fertilizer application increased exponentially with an increasing N surplus. By pooling all 121 on-farm experimental sites, an in-season root-zone N management strategy was shown to reduce the N application rate by 61% from 325 kg N ha(-1) to 128 kg N ha(-1) compared to the farmers' N practice, with no loss in wheat grain yield. As a result, the intensity of GHG emission and reactive N losses were reduced by 77% and 80%, respectively. The intensity of GHG emission and reactive N losses can be further reduced due to the improved N recovery and increased grain yield achieved by best crop management. In conclusion, N recovery efficiency and yield improvements should be used to reduce future agricultural N environmental footprints, rather than reducing the N application rate.
authors.affiliation: Center for Resources, Environment and Food Security, China Agricultural University, Beijing 100193, China.
authors.forename: Zhenling
authors.initials: Z
authors.lastname: Cui
authors.forename: Shanchao
authors.initials: S
authors.lastname: Yue
authors.forename: Guiliang
authors.initials: G
authors.lastname: Wang
authors.forename: Fusuo
authors.initials: F
authors.lastname: Zhang
authors.forename: Xinping
authors.initials: X
authors.lastname: Chen
mesh_terms: D000383:Agriculture / Q000379:methods; D002681:China; D005308:Fertilizers; D017752:Greenhouse Effect; D009566:Nitrates; D009584:Nitrogen; D009589:Nitrogen Oxides; D018517:Plant Roots; D014908:Triticum / Q000254:growth & development*
chemical_list: D005308:Fertilizers; D009566:Nitrates; D009589:Nitrogen Oxides; D009584:Nitrogen