PESTICIDE SOIL TRANSPORT MODELS - MODEL COMPARISONS AND FIELD-EVALUATION

Using an experimental data set obtained in a field trial in Italy, thr ee models forecasting pesticide behaviour in root/vadose zone of the s oil were tested. PRZM, BAM and LEACHM were used simulating metolachlor and atrazine at different depth of the soil. Input model parameters f or the chemodynamic herbicide properties, were obtained from literatur e data base while weather and soil data were derived from the experime ntal field. In all cases the results from the models agreed with the o bserved data in particular for the top soil. In the 30-50 cm - soil de pth, the measured and predicted concentrations were much variable and they agreed only in few cases within a magnitude factor of 5-10. The d ifferences between the models were measured mainly in soil hydrologica l balance.