Simulating the Impact of Nitrogen Management on Rice Yield and Nitrogen Uptake in Irrigated Lowland by ORYZA2000 Model

This paper considers the implications of ORYZA2000 model in simulating physiological traits of rice at different nitrogen concentrations. The experiment was conducted over the course of the growing season in 2012 and 2013 in Rice Research Institute, Deputy of Mazandaran, Iran. The variety used was Shiroudi as a high yielding variety. The considered factors were the amount of nitrogen at four levels (40, 80, 120, 160 kg N ha^?1 and control) and nitrogen splitting in four levels. We compared simulated and measured grain yield, biomass, grain nitrogen, total plant nitrogen uptake, and leaf area index (LAI) by Student’s t-test of means and by absolute and normalized root mean square errors (RMSE). Results showed that grain yield was simulated with an RMSE of 411–423 kg ha^?1 and a normalized RMSE of 6%. RMSE was 671–910 kg ha^?1 for biomass on harvesting date. RMSE were 7–11 for grain nitrogen, and 10–13 for total plant nitrogen uptake. LAI was simulated with a normalized RMSE of 17–23%. Generally the model simulated LAI, an exceeded measured value for different nitrogen treatments. The most obvious finding that emerged from this study was that ORYZA2000 model can be applied as a supportive research tool for selecting the most appropriate strategies for rice yield improvement at various nitrogen fertilization concentrations.