2005 Annual Report 4d.Progress report. This report documents research conducted under a reimbursable agreement between ARS and National Research Initiative Competitive Grants Program (NRI-CGP). Additional details of research can be found in the report for the in-house associated project, 3645-21220-003-00D, "Biological and Management Strategies to Increase Cropping Efficiency in Short-Season and High-Stress Environments." USDA-CSREES-NRI supported a three-year $400,000 proposal to develop improved weed emergence models. The proposal was entitled "Integrating continuous soil depth distributions of hydrothermal time, seeds, and burial tolerances to improve weed emergence models." This subordinate project will develop and integrate submodels of depth distributions in soil of seed placement (via tillage), soil burial tolerances of differing species, soil temperatures, and soil water potentials. The subordinate project coincides closely with the parent project (3645-21220-002-00D) in that a major thrust of the larger project was development of crop and weed emergence models. Funds from the subordinate project, which began in January 2005, allowed the CRIS project to hire a post-doctoral research associate, a programmer, and technical support. Two empirical submodels already have been developed. The first, SolarCalc, is a simplified routine that aids the simulation of hourly values of solar radiation for sites lacking equipment to measure this variable. Solar radiation data are necessary to simulate soil temperatures and soil water potentials, which are the primary drivers of weed seed germination. A manuscript has been submitted for this work. The second submodel, SeedChaser, simulates the distribution and redistribution of weed seeds (and any other soil-borne objects, such as insect eggs and larvae, fertilizer granules, etc.) after one or more passes of a wide array of soil tillage implements. Estimates of seed placement in soil are needed to better simulate the depth-specific effects of soil hydrothermal time of weed seed germination and early seedling growth. An has been submitted for this work. Technology transfer and outreach activities included: Use of a preliminary emergence model to help a strawberry grower decide when to apply a herbicide, to control common groundsel, a pernicious weed in horticultural crops. The team also plans to work closely with NC-202 Regional Research Committee to incorporate emergence models into decision support systems.