See more from this Session: Soil Carbon and Nitrogen: Microbial Transformations and Fluxes
Wednesday, October 19, 2011: 9:00 AM
Henry Gonzalez Convention Center, Room 006A, River Level
Models have been a useful tool for examination of possible impacts of management strategies and their impact in different climate change scenarios. The objectives of this work were: 1) to interpret and synthesize field observations of different management strategies on N2O fluxes at the local level; and 2) to perform simulations at the regional level under current conditions and at the IPCC emission scenario A2. The Denitrification DeComposition (DNDC) model was tested against annual data sets of N2O flux from corn at North Farm Experimental Station, Manhattan, KS. For regional modeling the USGS level 14 hydrologic unit code boundaries (HUC14 watersheds) were used as the mapping unit. A baseline scenario was evaluated based on meteorological data of the year 2000 from the Daymet model. Future N2O fluxes (2038-2070) predicted under the A2 emission scenario (IPCC,2007) were based on NARCCAP output from the HRM3 run using Hadley Global Climate Model (HadCM3) boundary conditions. Overall the predicted flux of N2O had a good fit with measured data (r2=0.84) in till and no-till corn systems, however predicted flux was poor for measured sub-surface and surface banded application of urea. In terms of cumulative flux the relative deviation of the predicted flux was 12%. Average N2O emissions ranged from 6.0 to 11.1 kg N-N2O/ha/yr for the baseline scenario. At the statewide level, for systems with no irrigation, modeled N2O emissions were lower by 4.6% for no-till comparing with till corn. The potential reduction for corn under irrigation was 6.6%. Under the emission scenario A2 the average N2O emissions were between 5.17 and 38 kg N-N2O/ha/yr in which till system had higher emissions than the no-till system. In summary, at site and regional level DNDC was able to detect reduction in N2O emissions due to conversion of conventional tillage to no-till in corn.