Abstract
The CERES-Maize of DSSAT model (Version 3.50) was evaluated under tropical conditions using data sets obtained from field experiments carried out on an acid sulphate soil in the central region of Thailand, in 1999 and 2000. The validation parameters were crop grain yield and N uptake. Nitrogen in the form of urea was applied via sprinkler irrigation at rates of 0 kg N, 100 kg N, 150 kg N, and 200 kg N ha-1. The soil was irrigated to field capacity based on 50% available soil moisture depletion regime throughout the season. Inputs to the model included site information, daily weather data, soil properties, soil initial conditions, irrigation and fertilizer management, and crop performance data. The weather data for 1999 and 2000 were collected from a weather station located 20 m from the field. The model performance was evaluated by comparing the observed and simulated values of grain yield and total N uptake using regression analyses and some error statistics such as average error (E) and relative error (RE). The results of the study showed that the regression coefficient (R2) values were 0.97 and 0.99 in both years for maize grain yield and total N uptake, respectively. The average for the simulated maize yield across all treatments were 106.2% and 103.4% of the observed yield values in 1999 and 2000, respectively. The average of simulated total N uptake across all treatments were 110.4% and 111 %, respectively, of the measured total N uptake values during 1999 and 2000. The results of the validation demonstrated agreement between the predicted and measured values. Although the study showed that the CERES-Maize of DSSAT model may be applied with confidence to study effects of N and irrigation management on maize yield and N uptake under irrigated tropical conditions, more validation under different soil and management conditions is recommended.
