Applying the CSM-CERES-Wheat model for rainfed wheat with specified soil characteristic in undulating area in Iran

Models can provide researchers with an opportunity to understand the multidimensional relationships among factors affecting crop growth. All such factors, including field condition, must be tested using models. The main objective of this study was to apply the Cropping System Model (CSM)-Crop-Environment Resource Synthesis (CERES)-Wheat model to uneven areas for simulating rainfed wheat. First, the model was calibrated at a field cultivated with wheat variety Sardari. The model was then applied to different points at a ‘hummocky’ evaluation site. At this site, 69 sample points from 5 different slope positions (summit, shoulder, backslope, footslope, and toeslope) were specified and physical and chemical soil properties as well as final grain and total aboveground wheat biomass at each of 69 points were measured. The overall results showed that the normalized root-mean-square error varied between 15% and 34% for the top weight; this was considered to be good enough for undulating areas. The model efficiency (EF) also ranged from 0.35 to 0.26 both in simulation of final grain and in top weight. It can be concluded that CSM-CERES-Wheat model can be effectively applied for yield prediction in hills. It should be noted that use of the CSM-CERES-Wheat model is not recommended for estimation of grain yield in individual slope positions unless more detailed water and fertilizer data are also available.