CALIBRATION OF THE CERES–MAIZE MODEL FOR SIMULATING SITE–SPECIFIC CROP DEVELOPMENT AND YIELD ON CLAYPAN SOILS

Abstract

Crop simulation models have historically been used to predict field average crop development and yield underalternative management and weather scenarios. The objective of this research was to calibrate and test a new version of theCERESMaize model, modified to improve the simulation of sitespecific crop development and yield. Seven sites within afield located in central Missouri were selected based on landscape position, elevation, depth to a claypan soil horizon, andpast yield history. Detailed monitoring of crop development and soil moisture during the 1997 season provided data forcalibration and evaluation of model performance at each site. Midseason water stress caused a large variation in measuredyield with values ranging from 2.6 Mg ha1 in the eroded sideslope areas to 10.1 Mg ha1 in the deeper soils located in thelow areas of the field. The model was calibrated against measured data for root zone soil moisture content, leaf area index,and grain yield. The results demonstrated that modifications included in the model to simulate root growth and developmentare important in soils with a highclay restrictive layer such as the claypan soils. Although the model performed well insimulating yield variability, simulated leaf area indices were below measured values at five out of seven monitoring sites,suggesting a need for model improvements. Results showed that accurate simulation of crop growth and development for areasof the study field that receive runon or subsurface flow contributions from upland areas will require enhancement of themodel to account for the effects of these processes.