Simulating Effects of Drought and Nitrogen Stress on Yield, Water and Nitrogen use Efficiency of Corn Using CERES-Maize Simulating Model

In order to simulate the effect of drought and nitrogen stress on grain yield, water and nitrogen use efficiency of corn CERES-Maize model was firstly calibrated and then validated. In the present research, t he CERES-Maize model was calibrated using field experiments which were conducted in 1995 and 2004 cropping years in Ahvaz and Ramin, respectively, then the model was evaluated using experimented data which was conducted in 2000 cropping year in Dezful (Safiabad). Normalized RMSE and index of agreement (d) were 4.2% and 0.97% for flowering date, 8.9% and 0.96 for physiological maturity and 12.6% and 0.70 for grain yield that the results showed that the model could reasonably work in this condition. Then the simulated model with six levels of drought stress (I) including irrigation after 30%, 40%, 50%, 60%, 70% and 80% depletion of field capacity and six levels of nitrogen application(N) including 50, 100, 150, 200, 250 and 300 Kg N ha-1 were assumed using Ahvaz long lasting barometer statistic was conducted. According to the simulation results drought stress has greater negative effect in high levels of nitrogen .Water use efficiency was increased a little due to decrease in used water. Through intensive drought stress, Nitrogen use efficiency decreased. Generally where irrigation water is limited and/or there is the probability of appearing of drought stress, reduction in nitrogen application can be very important for farmers for increase economical profit. Related to obtained results of this study, in Ahvaz climat condition and soil, in corn planting, it is recommended that irrigation conducted after 40%depletion of field capacity and 200kg Nitrogen used.