Click on “Download PDF” for the PDF version or on the title for the HTML version.

If you are not an ASABE member or if your employer has not arranged for access to the full-text, Click here for options.

In this study, DRAINMOD-N, a mathematical model for simulation of nitrate-nitrogen (NO3-N) concentration in water outflows (runoff and subsurface drain water) and shallow ground water, has been tested based on the field data collected from paddy rice fields consisting of a controlled drainage (CD) system in north of Iran during 2008 and 2009. The model performance was evaluated first by comparing the observed and simulated water table depth (WTD), that is an essential prerequisite for the model to obtain a proper prediction of NO3-N movement, and then by comparing the observed and simulated NO3-N concentration in shallow groundwater using two statistical indices, lowest root mean square error and the highest correlation coefficient. The lowest root mean square error and the highest correlation coefficient were determined to be 94.4 mm and 0.8 for water table differentiations, and 1.32 (mg/l) and 0.93 for NO3-N concentration, respectively. Therefore, it was found that DRAINMOD-N can be used to simulate soil hydrology and NO3-N concentration in shallow ground water of paddy rice field under controlled drainage CD management practices in north of Iran.