Submitted to: Meeting Proceedings
Publication Type: Abstract Only
Publication Acceptance Date: 4/3/2008
Publication Date: N/A
Citation: N/A Interpretive Summary: An interpretive summary is not required.
Technical Abstract: Artificial drainage systems can effectively transport excess water from agricultural soils. However, they can also affect the transport of biologically available nitrogen (N) to open waters and the emission of greenhouse gases from nearby soils. Using 12 large (30 x 33 cm) undisturbed soil columns, we examined N transport and transformation in three landscape positions (middle-field, near-ditch, in-ditch). Simulating field conditions, we raised the water table to the surface and then lowered it over 24 hours while monitoring volumetric soil water content, N leaching and carbon dioxide and nitrous oxide emissions. During water table rise and fall, soils from the ditch consistently emitted more nitrous oxide and carbon dioxide than the near-ditch and middle-field soils. The middle-field soils’ nitrous oxide emissions did not significantly differ from zero. At approximately 40 hours after the onset of the water table manipulation all landscape positions converged upon similar carbon dioxide and nitrous oxide emission rates. Traditionally, water filled pore space (WFPS) has accurately predicted nitrous oxide emissions in both models and the field. Consistent with this, our data demonstrated a significant Gaussian relationship between WFPS and nitrous oxide emissions. However, our data additionally indicated that field capacity, rather than a consistent per cent WFPS across landscapes, predicted peak nitrous oxide emissions regardless of landscape position or soil type. Furthermore, we found that WFPS at 10 cm better-predicted nitrous oxide emissions than WFPS at 20 cm or the mean for both depths.