title: Effect of topography on nitrous oxide emissions from winter wheat fields in Central France.
abstract: We assessed nitrous oxide (N(2)O) emissions at shoulder and foot-slope positions along three sloping sites (1.6-2.1%) to identify the factors controlling the spatial variations in emissions. The three sites received same amounts of total nitrogen (N) input at 170kgNha(-1). Results showed that landscape positions had a significant, but not consistent effect on N(2)O fluxes with larger emission in the foot-slope at only one of the three sites. The effect of soil inorganic N (NH(4)(+)+NO(3)(-)) contents on N(2)O fluxes (r(2)=0.55, p<0.001) was influenced by water-filled pore space (WFPS). Soil N(2)O fluxes were related to inorganic N at WFPS>60% (r(2)=0.81, p<0.001), and NH(4)(+) contents at WFPS<60% (r(2)=0.40, p<0.01), respectively. Differences in WFPS between shoulder and foot-slope correlated linearly with differences in N(2)O fluxes (r(2)=0.45, p<0.001). We conclude that spatial variations in N(2)O emission were regulated by the influence of hydrological processes on soil aeration intensity.
authors.affiliation: INRA, UR 0272 Science du Sol, Centre de Recherche d'Orléans, CS 40001 Ardon, 45075 Orléans Cedex 2, France. Jiangxin.Gu@orleans.inra.fr
authors.forename: Jiangxin
authors.initials: J
authors.lastname: Gu
authors.forename: Bernard
authors.initials: B
authors.lastname: Nicoullaud
authors.forename: Philippe
authors.initials: P
authors.lastname: Rochette
authors.forename: Daniel J
authors.initials: DJ
authors.lastname: Pennock
authors.forename: Catherine
authors.initials: C
authors.lastname: Hénault
authors.forename: Pierre
authors.initials: P
authors.lastname: Cellier
authors.forename: Guy
authors.initials: G
authors.lastname: Richard
mesh_terms: D005602:France; D009609:Nitrous Oxide / Q000737:chemistry*; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D014908:Triticum / Q000254:growth & development* / Q000378:metabolism; D014835:Volatilization
chemical_list: D012987:Soil; D009609:Nitrous Oxide