Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: 4/9/2009
Publication Date: 5/19/2009
Citation: Castellano, M., Schmidt, J.P., Kaye, J., Walker, C., Lin, H., Dell, C.J. 2009. Hydrological controls on nitrous oxide and carbon dioxide emissions across an agricultural landscape [abstract]. Penn State Plant Biology Symposium. p.1 Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Changes in hydrological controls on soil greenhouse gas emissions could result in important climate change feedbacks. Water table fluctuations into surface soils are “hot moments” of soil CO2 and N2O emissions. Future global change may affect the frequency and magnitude of water table fluctuations in surface soils: Increases in atmospheric CO2 may lead plants to reduce transpiration, raising the water table. A rise in water tables may result in more frequent saturation of surface soils, increasing greenhouse gas emissions. We evaluated soil hydrology controls on CO2 and N2O emissions during experimental water table fluctuations in large (33 x 33cm), relatively undisturbed soil cores. Cores were collected at three locations across a ditch-drained agro-ecosystem on the coastal plain of Maryland, USA: in-ditch, near-ditch and middle-field. The soils from these three locations vary in hydrological properties. Simulating field data, cores were flooded from the bottom to the surface. Subsequently, the cores were drained while monitoring volumetric soil moisture, matric potential, CO2 and N2O emissions. As predicted by previous work, N2O emissions were a function of water filled pore space (WFPS). However, peak N2O emissions did not occur at a consistent WFPS (range: 64%-86% WFPS). In contrast, peak N2O emissions occurred at a relatively narrow range of matric potential (range: -3 to -5 kPa). These data suggest that water filled pore size distribution, rather than WFPS, controls the magnitude of N2O emissions.