A WARM-SEASON ANNUAL GRASS GROWTH-MODEL PARAMETERIZED FOR MAIZE AND SUDANGRASS

A process-based, warm-season annual grass growth model named WANGRO was developed to simulate the grass component of a legume-grass rotation under water limiting conditions. The model is parameterized for maize (Zea mays L.) and sudangrass (Sorghum bicolor (L.) Moench var. sudanense Piper) dry matter production. The processes modeled are crop emergence, canopy light absorption and shoot growth, dry matter partitioning into above-ground plant parts, evapotranspiration, and root growth. Model detail is relatively limited to facilitate the goal of model use in management. Processes are simulated with daily integration time steps. A unique feature of the model is that maize and sudangrass are simulated from planting to physiological maturity by modifying only three crop specific parameters. The input requirements of the model are weather data (temperature, rainfall and solar radiation), soil parameters, and management data. The potential of the model for general applicability to the crop growing conditions of the Northeast is indicated by good agreement of the model yield predictions with the corresponding field data. Model predicted dry matter yields were within 15, 13 and 12% of the field-observed yields for maize grain, maize silage, and sudangrass above-ground biomass, respectively.