Evaluation and comparison of pesticide leaching models for registration purposes

The results of three Swedish lysimeter studies performed in the years from 1989 to 1991 were used to test the capability of the Pesticide Leaching Model (PELMO). This model is used in Germany within the registration procedure for pesticides. While the water movement in the soil was simulated satisfactorily, the simulated behavior of the pesticides bentazon and dichlorprop agreed with the lysimeter measurements only if preferential flow was not the dominant process. Prediction of rapid movement through macropores in the soil is not possible using PELMO.