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Modeling impacts of farming management practices on greenhouse gas emissions in the oasis region of China

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Author(s): Y. Wang | G. J. Sun | F. Zhang | J. Qi | Z. D. Feng | C. Y. Zhao

Journal: Biogeosciences Discussions
ISSN 1810-6277

Volume: 8;
Issue: 2;
Start page: 3121;
Date: 2011;
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ABSTRACT
Agricultural ecosystems are major sources of greenhouse gas (GHG) emissions, specifically nitrous oxide (N2O) and carbon dioxide (CO2). An important method of researching GHG emissions in agricultural ecosystems is model simulation. Field measurements quantifying N2O and CO2 fluxes were taken in a summer maize ecosystem in Zhangye City, Gansu Province, in northwestern China in 2010. Observed N2O and CO2 fluxes were used for validating flux predictions by a DeNitrification-DeComposition (DNDC) model. Then the validated DNDC model was used for sensitivity tests on three variables under consideration: climatic factors, soil properties, and agricultural management. Results indicate that: (1) the factors that N2O emissions are most sensitive to nitrogen fertilizer application rate, manure amendment and residue return rate; (2) CO2 emission increases with increasing manure amendment, residue return rate and initial soil organic carbon (SOC); and (3) net global warming potential (GWP) increases with increasing N fertilizer application rate and decreases as manure amendment, residue return rate and precipitation increase. Simulation of the long-term impact on SOC, N2O and net GWP emissions over 100 yr of management led to the conclusion that increasing residue return rate is a more efficient method of mitigating GHG emission than increasing fertilizer N application rate in the study area.
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