2008 Annual Report 1a.Objectives (from AD-416) Assess how converting Conservation Reserve Program lands to grasslands managed for domestic livestock grazing and no-till croplands effects elements of C Cycling, particularly system CO2 exchange and hydrology. This research will be conducted at the USDA-ARS Rangeland Resources Research Unit, Crops Research Lab, Ft. Collins, CO, the Dept. of Soil and Crop Sciences and the Natural Resource Ecology Lab., Colorado State University. Projects will be collaborative efforts, in which both the Cooperator and ARS co-lead in the preparation, planning, and the execution of experiments. 1b.Approach (from AD-416) Eddy-covariance towers will be operated for a final year on the Jim Curtis ranch to better evaluate inter-annual variability in grassland carbon and water dynamics in grazed and un-grazed treatments, and the change in carbon stocks, and carbon and water fluxes, during restoration of the dry-land agricultural treatment to grassland. During this project the long-term flux data base will be processed and analyzed and results will be summarized and interpreted in regard to the impacts of grazing and cropping system practices on ecosystem functioning, with an emphasis on the C Cycle. Results will be disseminated via peer-reviewed publications and meetings and through outreach effort to land owners and public land managers. 3.Progress Report The objective of the research is to assess how converting Conservation Reserve Program (CRP) lands to grasslands managed for domestic livestock grazing and no-till croplands effects elements of C Cycling, particularly system CO2 exchange and hydrology. All field measurements were concluded in this final year of the project. The eddy flux towers were dissembled and removed from the three pastures (non-grazed CRP, grazed CRP, and CRP land that had been converted to winter wheat) where the effects of grazing and conversion of CRP land to cropland on C fluxes had been monitored. Data from this project are currently being analyzed, and manuscripts prepared for submission to journals for publication. Over the course of the project, we observed little net effects of livestock grazing on land-atmosphere exchanges of energy and CO2 of CRP lands. The results suggest that CRP lands could be converted to other uses (occasional grazing; cropping) with minimal effects on C balance. To ensure accountability of funds utilized in this collaboration, the ADODR corresponds at least quarterly with Colorado State University collaborators to discuss research findings, deal with issues at the experimental site, including managing the CRP lands that were converted to crops or grazing, and planning for a manuscript.