BiogeochemistryISI Document Delivery No.: EF0NGTimes Cited: 0Cited Reference Count: 66Buysse, Pauline Flechard, Chris R. Hamon, Yannick Viaud, ValerieNational Research Agency (France) [ANR-12-AGRO-0005]This research was funded by the National Research Agency (France) within the MOSAIC project (ANR-12-AGRO-0005). The investigations benefited from the support of INRA and CNRS for the Research Observatory ORE AgrHys, and from Allenvi for the SOERE RBV. Data are available at http://geowww.agrocampus-ouest.fr/web/. The authors also thank Armelle Racape (INRA Rennes-Agrocampus-Ouest-UMR 1069) and Patrice Petitjean (University of Rennes I, Geosciences-Rennes UMR6118) for DOC sample preparation and analysis.SpringerDordrecht ; Within the context of climate change, it is necessary to improve our mechanistic understanding of processes that release CO2 to the atmosphere. This study was designed to investigate spatial variation of soil CO2 efflux (F-CO2) at the landscape (catchment) scale, which has received less attention so far in comparison to more homogeneous, smaller areas. More specifically, this study investigated the impacts of water regime, land-use and crop rotation on F-CO2 in a small temperate agricultural catchment. F-CO2 was measured manually with closed dynamic chambers over a 1 year period (36 weekly to bi-weekly measurement dates) at 22 sites that were selected to represent most of the diversity of drainage classes, soil types and land-uses in a small catchment in North-Western France. F-CO2 was modelled empirically at each site as a function of soil temperature and soil water content. As a secondary step, impacts of water regime, land-use and crop rotation on heterotrophic respiration (HR) were also sought, with HR being estimated empirically as a fraction of F-CO2 on the basis of partitioning coefficients taken from the literature. Results showed that water regime, land-use and crop rotation all had significant impacts on F-CO2 on an annual scale. Poorly-drained sites emitted less CO2 than well-drained and moderately-well drained sites, which could be explained by reduced soil CO2 production and/or limitations in soil transport in more saturated environments. In addition, larger annual F-CO2 were measured on grasslands compared to croplands (wheat and maize crops), which is likely due to the presence of larger amounts of available soil carbon and nutrients and to the presence or denser rooting systems. Due to the literature-based determination of partitioning coefficients, the results related to HR estimates were affected by more uncertainties than those related to F-CO2 but they showed that the water regime tended to impact them similarly as F-CO2, while HR was likely less affected by land-use. Altogether, the results of this study, performed at scale of a small agricultural temperate catchment, confirm that specific patterns of F-CO2 result from varying soil CO2 production and transport processes, resulting from complex interactions between soil environment characteristics (soil carbon content, water regime,aEuro broken vertical bar) and land-use/crop rotations.