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Poster Abstracts

Poster Title: Comparison of DAYCENT-simulated and measured nitrous oxide emissions from bioenergy cropping systems

Authors: Paul Adler, Curt Dell, Tamie Veith, Steve Del Grosso (USDA-ARS); Bill Parton (NREL)

Poster Abstract: The land use impacts, such as nitrous oxide (N2O) emissions and soil carbon sequestration, are associated with the largest changes in life cycle greenhouse gases from growing bioenergy crops. The biogeochemical model DAYCENT simulates fluxes of carbon (C) and nitrogen (N) between the atmosphere, vegetation, and soil. From weather, soil-texture class, and land-use inputs, DAYCENT simulates crop production, soil organic-matter changes, and trace-gas fluxes. The objective of this study was to evaluate the ability of DAYCENT to simulate measured N2O emissions, the largest greenhouse gas source, from 3 bioenergy cropping systems. Switchgrass, reed canarygrass, and a corn rotation with soybeans and alfalfa were grown in central Pennsylvania. Nitrous oxide emissions were measured weekly during the growing seasons (biweekly during extended dry periods) and periodically at other times of the year. Daily simulated N2O flux overlapped with observed interquartile and max-min ranges 40% and 80% of the time on average, respectively. Given the high variability of N2O fluxes in natural systems, DAYCENT captured the observed daily variability in N2O emissions and simulated the observed seasonal patterns within bioenergy crops and differences in annual mean emissions among systems reasonably well.