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Gu 2011 Env Polln N2O topography

By khof - Posted on 28 October 2011

Effect of topography on nitrous oxide emissions from winter wheat fields in Central France
Jiangxin Gu, Bernard Nicoullaud, Philippe Rochette, Daniel J. Pennock, Catherine Hénault, Pierre Cellier, Guy Richard

We assessed nitrous oxide (N2O) 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 170 kg N ha−1. Results showed that landscape positions had a significant, but not consistent effect on N2O fluxes with larger emission in the foot-slope at only one of the three sites. The effect of soil inorganic N (NH4+ + NO3−) contents on N2O fluxes (r2 = 0.55, p < 0.001) was influenced by water-filled pore space (WFPS). Soil N2O fluxes were related to inorganic N at WFPS > 60% (r2 = 0.81, p < 0.001), and NH4+ contents at WFPS < 60% (r2 = 0.40, p < 0.01), respectively. Differences in WFPS between shoulder and foot-slope correlated linearly with differences in N2O fluxes (r2 = 0.45, p < 0.001). We conclude that spatial variations in N2O emission were regulated by the influence of hydrological processes on soil aeration intensity.

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