Improvement of DSSAT CSM‐CROPGRO‐Cotton model for response to water, nitrogen, weather, and management

The goal of this study was to update the CSM‐CROPGRO‐Cotton model for its ability to simulate cotton ( Gossypium hirsutum L.) lint yield and cardinal temperature effects on physiological processes, followed by a thorough recalibration against extensive data on seed‐cotton yield, lint yield and percentage, crop mass, and time series growth data collected on 11 cotton cultivars in 143 treatments over 21 site‐years in Arizona, Texas, Georgia, and North Carolina (where CSM is Cropping System Model). Model parameters were updated for seed‐cotton composition, cardinal temperatures for critical processes, and dependency of lint percentage on temperature, drought and N stress, and cultivar. The D ‐statistic for time series variables averaged over all site treatments was 0.947, 0.977, 0.896, 0.865, 0.937, 0.978, 0.955, and 0.974 for canopy height, total crop mass, leaf area index, leaf mass, stem mass, boll mass, boll harvest index, and vegetative stage, respectively. Additional data from 46 treatments in 10 site‐years in Mississippi were used for calibrating lint yield and percentage. For these treatments, relative root mean square error (RRMSE) was 16.5%, 20.0%, 20.7%, and 2.7% for crop mass, seed‐cotton yield, lint yield, and percentage, while respective D ‐statistics were 0.871, 0.822, 0.786, and 0.795. For end‐of‐season outputs across treatments in all 31 site‐years of experiments, RRMSE was 14.5%, 25.9%, 22.4%, and 6.0% for crop mass, seed‐cotton yield, lint yield, and percentage, while respective D ‐statistics were 0.950, 0.925, 0.955, and 0.869. The model was successfully evaluated against lint yield and percentage for the 1999–2019 Arkansas cotton variety trials. The improved model, its parameters, and appropriate experimental files will be included in a future release of DSSAT (Decision Support System for Agrotechnology Transfer).