Pesticide leaching modelling validation -: A recent European experience

Testing of pesticide leaching models is important in view of their increasing use in pesticide registration procedures in the European Union. This paper summarises the major conclusions and recommendation of a recent experience on pesticide-leaching models and modelling validation. Twelve models simulating the vertical I-dimensional movement of water, solute, heat, and, in particular, pesticides, through the soil profile were used by 36 different model users. The models differ in terms of modelling concepts. Four quality data sets were identified to perform the analysis. The data set included field and lysimeter data, collected in the Netherlands, Germany, Italy and the United Kingdom. Non-structured as well as structured soils were available in the data set. To elucidate the ability to model correctly water transport, solute transport, heat transport and pesticide transport in soils, a stepwise evaluation approach was followed. Splitting up the experimental data set enabled us to quantify the calibration capability and the prediction capability of the models. The simulations were performed by different model users enabling us also to characterise output variability in terms of user dependent interpretation of the model input and parameters. This paper resumes the major conclusions and recommendations. Details of the modelling exercise are given in [30].