Evaluation Of The PRZM2 Model For TransportOf Metamitron In Undisturbed Soil Monoliths

The predictive capability of the PRZM-2 model for the herbicide Metamitron under our agricultural conditions was investigated. Model predictions were compared with data on percolation and herbicide concentration collected in undisturbed soil monoliths during 1995 in Valladolid (Spain). Soil temperature, evapotranspiration, percolation and net pesticide flux past the maximum root depth were used to evaluate the model response. The results suggests that the hydrologic components of the model are relatively accurate, but percolation was overpredicted in months where evapotranspiration was high. Our special experimental conditions are assumed to be the responsible for this overprediction during the summer months. Despite of this overprediction, the model provided reasonably predictions for the concentrations and mass of the herbicide recovered below the root zone.