Usefulness of models for the prediction of run-off events - comparison with experimental data

Considerable amounts of pesticides can be transported to adjacent areas with surface run-off when adsorbed to eroded soil. Within an assessment scheme considering the pesticide's hazard for the non-target area, apart from basic information on agricultural and chemical properties (e.g. sorption, water solubility), predictive modelling is important. To predict the amount of pesticides attaining to adjacent ecosystems computer models have been developed. Usually, soil and climate data as well as geometric data of the agricultural field (e.g. slope and slope length) are required for a simulation. To compare the quality of the results of computer models with field data run-off experiments (rainfall simulation on small plots of about 7 qm shortly after application) using the pesticides bifenox, dichlorprop-p and isoproturon were carried out. Based on these results the modules of the computer model PELMO (Pesticide Leaching Model) calculating the pesticide's transport were improved by modific ations.