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.
The CropSyst modeling platform is being modified to better simulate multispecies pastures. Pasture plant competition for water is being incorporated using the approaches demonstrated in previous pasture models, and based on greenhouse tests of model predictions using both model (corn/sunflower) and forage species (white clover/orchardgrass). Field variety trial data from New York and Pennsylvania were collected, and used to assess the accuracy of the CropSyst predictions. The addition of plant competition for nutrients, planned for FY2014, will improve simulation accuracy. The improved CropSyst model will be used to simulate water and nutrient cycling and the impact of conservation practices in pastures.