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

• Main Authors: Y. Wang, G. J. Sun, F. Zhang, J. Qi, C. Y. Zhao
• Format: Article
• Language: English
• Published: Copernicus Publications 2011-08-01
• Series: Biogeosciences
• Online Access: http://www.biogeosciences.net/8/2377/2011/bg-8-2377-2011.pdf
• ISSN: 1726-4170; 1726-4189

Agricultural ecosystems are major sources of greenhouse gas (GHG) emissions, specifically nitrous oxide (N<sub>2</sub>O) and carbon dioxide (CO<sub>2</sub>). An important method of investigating GHG emissions in agricultural ecosystems is model simulation. Field measurements quantifying N<sub>2</sub>O and CO<sub>2</sub> fluxes were taken in a summer maize ecosystem in Zhangye City, Gansu Province, in northwestern China in 2010. Observed N<sub>2</sub>O and CO<sub>2</sub> fluxes were used for validating flux predictions by a DeNitrification-DeComposition (DNDC) model. Then sensitivity tests on the validated DNDC model were carried out on three variables: climatic factors, soil properties and agricultural management. Results indicated that: (1) the factors that N<sub>2</sub>O emissions were sensitive to included nitrogen fertilizer application rate, manure amendment and residue return rate; (2) CO<sub>2</sub> emission increased with increasing manure amendment, residue return rate and initial soil organic carbon (SOC); and (3) net global warming potential (GWP) increased with increasing N fertilizer application rate and decreased with manure amendment, residue return rate and precipitation increase. Simulation of the long-term impact on SOC, N<sub>2</sub>O 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.