Simulation of durum wheat (Triticum turgidum ssp. durum) growth under different water and nitrogen regimes in a mediterranean environment using CropSyst

Abstract

CropSyst, a cropping system simulation model, was evaluated for its ability to simulate growth, yield, and water and nitrogen use of two wheat cultivars (Cham I and Hourani). These cultivars were grown under different water (rainfed, 60% and 100% of crop water requirements) and nitrogen (without and with 100 kg N/ha) regimes in a Mediterranean type of environment at the Tel Hadya Research Station of ICARDA. Data from three contrasting growing seasons (1989/90 to 1991/1992) were used in these simulations. Soil characteristics, initial conditions of available moisture, N and organic matter, and daily weather data were input to CropSyst. Crop input parameters were mostly selected from the model documentation or determined from the experimental data. A few cultivar-specific parameters were adjusted within a narrow range of typical fluctuation by model calibration. Results showed that CropSyst was generally able to simulate evapotranspiration, crop N content, green leaf area, aboveground biomass, and grain yield as observed in the field experiments. Overall, the magnitude of the root mean square errors,vas about 10% of the observed means with two exceptions (25% and 32%). Index of agreement between predicted and observed values fluctuated from 0.90 to 0.98 (a value of 1.0 indicating excellent agreement), with most values equal or better than 0.95.