2005 Annual Report 4d.Progress report. This report serves to document research conducted under Specific Cooperative Agreement #58-5402-4-0387 between ARS and Colorado State University. Additional details of research can be found in the report for the parent project 5402-11000-007-00D Interactions Between Land Use Land Management, and Climate Change: Relations to Carbon and Nitrogen Cycling, Trace Gases and Agroecosystems. The 2006 U.S. Agriculture and Forestry Greenhouse Gas Inventory and subsequent inventories will incorporate new methodologies that apply the most recent advances in the DAYCENT computer simulation model. DAYCENT will be used to estimate greenhouse gas emissions from major cropping systems and rangelands in the U.S. CSU has the computing resources and programming personal required to run DAYCENT that the Soil Plant Nutrient Research Unit lacks. SPNR has worked with CSU to improve the crop growth submodel in DAYCENT and to acquire climate, soils, and land use data needed to drive the model at the county and sub-county levels. Programming staff and computer hardware housed at CSU have also assisted SPNR in developing a prototype SQL database which can be also be adapted for use in developing the ARS GRACEnet data base.