Fig. 8. Comparison between the model-predicted and measured grain N uptake for the 200, 400, 600, and 800 kg N ha^–1 yr^–1 (WC200N, WC400N, WC600N, and WC800N, respectively) treatments during 2001 to 2003. Error bars represent ± one standard deviation of the measured grain N uptake from the mean of replications.