Simulation of Climate Change Impacts On Wheat-Fallow Cropping Systems.

Agricultural system simulation models are predictive tools for assessing climate change impacts on crop production. In this study, RZWQM2 that contains the DSSAT 4.0-CERES model was evaluated for simulating climate change impacts on wheat growth. The model was calibrated and validated using data from the Free Air CO₂ Enrichment (FACE) experiment conducted at Maricopa, Arizona, USA from 1992 to 1997. The validated model was then used to simulate possible climate (temperature, CO₂, and precipitation) change impacts on wheat-fallow rotations under conventional tillage (CT) and no tillage (NT) at Akron, Colorado, USA. Historical climate (1912-2007) and General Circulation Model (GCM) projected climate change scenarios were used. Simulations of the FACE experiment demonstrated that the crop model reasonably simulated wheat responses to elevated CO₂ conditions. Enhanced water use efficiency under the elevated CO₂ was also correctly simulated. Simulation results with the historical climate showed that tillage affected crop growth more than CO₂. Under both CT and NT, simulations with the projected climate showed that production decline due to temperature change can dominate over the CO₂ fertilization effect on crop yield in the semiarid condition of Colorado. The study demonstrated the potential of RZWQM2 for climate change impact assessments.

Keywords: Climate change, CO₂, crop model, FACE, precipitation, temperature, yield