The DRAINMOD-N II, which is a based field scale model for predicting Nitrogen, was successfully calibrated and validated using data sets from two experimental plots located at the North-East of Egypt over a period of one year (2009–2010). Lateral drains were installed at 12 m spacing in the first plot and at 18 m in the second plot. Both plots were cultivated with cotton during the summer of 2009 followed by wheat during the winter of 2009/2010. The quantity and quality of irrigation and drainage water were monitored for both sites over the two cropping seasons. DRAINMOD-N II was calibrated using data from the first plot, while data set from the second plot was used for model validation over the two cropping seasons. The model simulation results were evaluated statistically by comparing the simulated and measured drain flows and nitrate–nitrogen (NO₃–N) losses in the subsurface drains.

The study results showed good agreement between the observed and simulated results for both plots. The mean absolute error (MAE) of the drainage rate was less than 0.08 cm for the calibration plot over the two cropping seasons. The MAE results for the prediction of NO₃–N drainage losses were 0.028 and 0.035 kg NO₃–N/Feddan during cotton season and wheat season, respectively for the calibration plot. During the same period, MAE of the drainage rate was less than 0.04 cm for the validation plot. The MAE of NO₃–N drainage losses was 0.024 and 0.013 kg NO₃–N/Feddan during cotton season and wheat season, respectively for the validation plot. These results prove the DRAINMOD-N II capability to simulate nitrogen losses from the newly reclaimed agricultural lands under the Egyptian conditions.