HR: 1340h
AN: B43A-0259    [Abstracts]
TI: Soil Surface CO2, CH4 and N2O Fluxes in Relation to Ecosystem Respiration and Global Warming Potential in Great Plains Agroecosystems
AU: * Arkebauer, T J
EM: tja@unl.edu
AF: University of Nebraska-Lincoln, 106 KCR Bldg. Department of Agronomy and Horticulture, Lincoln, NE 68583-0817 United States
AB: Recent changes in global climate have been characterized by increasing atmospheric concentrations of CO2, CH4 and N2O. The maize-based cropping systems that dominate the Great Plains region of the United States may possible have significant carbon sequestration potential; however, potentially adverse effects from altered trace gas fluxes must also be considered. The primary goal of our program is to quantify ecosystem respiration and global warming potentials in maize-based agroecosystems through continuous year-round measurements of soil surface CO2, CH4 and N2O fluxes combined with estimates of canopy respiration based on single leaf gas exchange measurements. Preliminary results show significant variability in soil surface gas flux on diel, seasonal, and annual time scales. Measured soil surface CO2 fluxes varied more on a diel scale than did CH4 and N2O fluxes. The diel CO2 flux variability was associated with near-surface soil temperature. Seasonal variability in surface gas exchange was related to patterns of crop growth and biomass production. Soil moisture content also affected surface gas exchange. The ratio of daily soil respiration to nighttime canopy respiration was always above one which implies that soil respiration is the largest component of ecosystem respiration in these agroecosystems.
DE: 0402 Agricultural systems
DE: 0428 Carbon cycling (4806)
DE: 0438 Diel, seasonal, and annual cycles (4227)
DE: 0490 Trace gases
SC: Biogeosciences [B]
MN: Fall Meeting 2005