The carbon budget of a winter wheat field: An eddy covariance analysis of seasonal and inter-annual variability

Schmidt, M.; Reichenau, T.; Fiener, P.; Schneider, K.

doi:10.1016/j.agrformet.2012.05.012

Journal Article

PreJuSER-22446

The carbon budget of a winter wheat field: An eddy covariance analysis of seasonal and inter-annual variability

Schmidt, M.FZJ* ; Reichenau, T. ; Fiener, P. ; Schneider, K.

2012
Elsevier Amsterdam [u.a.]

Agricultural and forest meteorology 165, 114 - 126 (2012) [10.1016/j.agrformet.2012.05.012]

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Please use a persistent id in citations: doi:10.1016/j.agrformet.2012.05.012

Abstract: Arable land occupies large areas of global land surface and hence plays an important role in the terrestrial carbon cycle. Therefore agro-ecosystems show a high potential of mitigating greenhouse gas emissions while optimizing agricultural management. Hence, there is a growing interest in analyzing and understanding carbon fluxes from arable land as affected by regional environmental as well as management conditions. The major goal of this study is to use a two year data set of eddy covariance measurements (October 2007 to October 2009) on a winter wheat field located in Western Germany to assess the seasonal and inter-annual variability of carbon fluxes as affected by meteorological variables and land management. During the study period, which was comprised of two full growing seasons, eddy covariance measurements together with measurements of various soil, plant, and meteorological data were performed. Flux partitioning and gap filling methods including uncertainty estimates were applied to derive complete time series of net ecosystem exchange (NEE), gross primary production (GPP), and ecosystem respiration (R-eco). Despite different management dates and slightly different meteorological conditions, annual NEE resulted in 270 g C m(-2) in both years. Although the period from sowing to harvesting was more than 20 days shorter in the first year, due to the later start of senescence, GPP was higher by 220 g C m(-2). In the annual carbon budget this was compensated by a stronger heterotrophic respiration after the harvest of sugar beet grown on the field before the study period. Taking into account the carbon losses due to removal of biomass during harvest, the winter wheat field acts as a carbon source with respective net biome productivities (NBP) of 246 and 201 g C m(-2) a(-1). To complete the carbon balance, releases due to energy consumption associated with crop production are taken into account. However, the relatively large carbon loss was probably, to a large extent, compensated by carbon input from plant residues left on the field after preceding sugar beet harvest. This underlines the importance of multi-annual measurements taking full crop rotations into account. (C) 2012 Elsevier B.V. All rights reserved.

Keyword(s): J ; Winter wheat (auto) ; Crop carbon balance (auto) ; Net ecosystem exchange (auto) ; Gross primary production (auto) ; Ecosystem respiration (auto) ; Eddy covariance (auto)

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Note: We gratefully acknowledge financial support by the project GLOWA-Danube, funded by the German Federal Ministry of Education and Research (BMBF-No. 56404005) and the SFB/TR 32 "Pattern in Soil-Vegetation-Atmosphere Systems: Monitoring, Modelling, and Data Assimilation" funded by the Deutsche Forschungsgemeinschaft (DFG). We also would like to thank A. Knaps from the Forschungszentrum Julich for the provision of meteorological data. Special thanks go to our students for their assistance during field work, to farm manager F. Moes for granting access to his field, to Regine Spohner for cartography and figure layout, and to Karen Schneider for proofreading.

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