2007 Annual Report 1a.Objectives (from AD-416) Build a framework for weed emergence models that is integrated with hydrothermal times and summed across soil depths, to generate more realistic weed emergence curves. 1b.Approach (from AD-416) Integrate soil microclimate through soil physical models with depth distributions of seeds. 3.Progress Report This report serves to document the accomplishments under a Reimbursable Agreement between ARS and USDA-CSREES-NRI. Additional details of research can be found in the parent project 3645-21220-003-00D. NRI supports a three-year $400,000 project to develop improved weed emergence models. This subordinate project is developing and integrating submodels of depth distributions in soil of seed placement (via tillage), soil burial tolerances of differing species, soil temperatures, and soil water potentials. Three 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. SolarCalc was published in the journal Weed Science in 2006. A second submodel, SolarCalcQ, was developed in cooperation with and funding from the University of Chicago. SolarCalcQ simulates radiation as SolarClac, but also estimates spectral quality at any geographical location on earth. It also contains necessary computer code to control artificial lighting in incubators to duplicate predicted spectra around the globe, as well as estimate air temperature and relative humidity at one-minute time steps. The third 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. SeedChaser was published in the journal Weed Science in 2007. Monitoring activities: Project team met and made site visits regularly to ensure that experiments and analyses were progressing at the expected pace. One team member transferred to another ARS location, but collaboration was frequent through e-mail. Team members were invited to make joint presentations on progress of project, which reinforced cross communication. 6.Technology Transfer Number of non-peer reviewed presentations and proceedings 5 Number of newspaper articles and other presentations for non-science audiences 4