Using LEACHM to predict NO₃-N in monolith lysimeters

Leaching Estimation And Chemistry Model (LEACHM) was modified by introducing a macropore flow component from Root Zone Water Quality Model (RZWQM). NO3-N concentration data obtained from field scale monolith weighing lysimeter experiments were used to calibrate and validate the nitrogen version of LEACHM model in its original form and with the addition of macropore flow component to it. Simulated profile of NO3-N concentrations were compared with the measured data collected from five different depths of the lysimeter profile. Though addition of the macropore flow component improved the predictions, the difference between predicted and observed data was still large. Discrepancy between measured and predicted data may be attributed to the large spatial variability of the measured data and possible errors Involved with the estimation of important soil physical properties.