|Del grosso, Stephen|
Submitted to: Ecological Society of America Proceedings
Publication Type: Abstract only
Publication Acceptance Date: 6/2/2003
Publication Date: 7/22/2003
Citation: DEL GROSSO, S., MOSIER, A.R., OJIMA, D., PARTON, W., KEOUGH, C. USING THE DAYCENT ECOSYSTEM MODEL TO ASSESS GREENHOUSE GAS EMISSIONS FROM AGRICULTURAL SYSTEMS IN THE US.. ECOLOGICAL SOCIETY OF AMERICA PROCEEDINGS. 2003. Interpretive Summary:
Technical Abstract: As a signatory of the Framework Convention on Climate Change the US is required to conduct annual greenhouse gas (GHG) inventories. Agriculture is not a strong source of CO2 emissions, but is responsible for a significant proportion of anthropogenic emissions of N2O and CH4. Although the atmospheric concentrations of N2O and CH4 are small compared to CO2, they have a higher global warming potential than CO2 on a per molecule basis. Currently, GHG emissions from the agricultural sector are estimated using the Intergovernmental Panel on Climate Change (IPCC) emission factors. For example, 1.25% of total N fertilizer applied to crops is assumed to be lost as N2O emissions. To improve GHG flux estimates, we combined climate, soils, and land management data from various sources to make input files required by DAYCENT. DAYCENT is an ecosystem model used to investigate the effects of changes in land use and climate on C and N fluxes. The US was divided into 63 regions and the most common agricultural practice within each region was represented in the model. Direct N2O emissions from soil as well as indirect N2O emissions associated with NO3 leaching, NH3 volatilization, and NOx emissions were summed for each region. Simulated crop yields, N gas emissions, and NO3 leaching were compared with field data to test model performance. Comparisons of DAYCENT simulated N2O emissions with site level data show that DAYCENT matches observations better than N2 O emissions calculated using the IPCC method for most sites tested. Model results suggest that corn/soy cropping in the Midwest stores 25g C m-2 annually and wheat cropping stores about half as much C. However, the C equivalents of N2O emissions are higher for corn/soybean rotations ( 20g CO2-C m-2 yr-1) than wheat cropping (15g CO2-C m-2 yr-1).