2012 Annual Report 1a.Objectives (from AD-416): 1) Develop a model of pasture management incorporating multiple forage species and mechanistic nutrient cycling;. 2)test model predictions against measured data collected on farms in the northeastern United States; and. 3)employ the model in the context of Grazingland CEAP to understand and predict the environmental implications of conservation practices in temperate pastures of the northeastern United States. 1b.Approach (from AD-416): Existing rangeland models are widely used, but are inadequate for the very different climatic conditions, dominant species, and management strategies used in temperate humid pastures. Existing mono- and multi-species models will provide the initial framework for development of a new mechanistic pasture model simulating plant growth, competition, and nutrient cycling in pastures. The model will be validated using on-farm data collected as part of ongoing ARS research. Model findings will contribute to both Grazingland CEAP efforts and to developing recommendations for pasture management. 3.Progress Report: A doctoral student has been employed on this project, and has begun research on model plant species needed to modify an existing model of cropping systems for use with multispecies perennial pastures. Preliminary research results will be presented at the Crop Science Society of America meeting.