2012 Annual Report 1a.Objectives (from AD-416): 1) Evaluate interactions among nitrogen, carbon, soil water, and crop growth response across a range of soil types in a production field; and. 2)Evaluate field scale decision support system for nitrogen and crop management. 1b.Approach (from AD-416): Field scale studies will be developed to evaluate nitrogen response to varying soil water regimes across a production field and the carbon dynamics in response to nitrogen management. Corn-soybean rotations will be evaluated over three growing seasons. Water, CO2, nitrogen and light exchanges will be measured at several field locations within the field. 3.Progress Report: This agreement has focused on the implementation and evaluation of farming systems which govern production efficiency in corn and soybean production systems. Measurements of energy balance, crop growth and yield, and production inputs across a production field have been made for 14 growing seasons. The current manipulation includes addition of side-dress nitrogen on corn coupled with fungicide applications. The addition of the side-dress nitrogen improved yields; however, the fungicide treatment did not increase yields above the non-treated areas. The field-scale experiments allow for an assessment of the impacts of different soils and in the side-dress nitrogen studies there was a greater effect on the soils with less organic matter.