A European test of pesticide-leaching models: methodology and major recommendations

Testing of pesticide-leaching models is important in view of their increasing use in pesticide registration procedures in the European Union. This paper presents the methodology and major conclusions of a test of pesticide-leaching models. Twelve models simulating the vertical onedimensional movement of water, solute, heat, and, in particular, pesticides, through the soil pro®le were used by 36 different modellers. The adopted modelling codes differ in terms of modelling concepts and modelling hypothesis. Modellers were af®liated to industry and to the scienti®c community as well. Four quality datasets were identi®ed to perform the analysis. The dataset included ®eld and lysimeter data, collected in the Netherlands, Germany, Italy and the UK. As well, non-structured as structured soils were available in the dataset. 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 dataset 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. Recommendations are formulated for Agricultural Water Management 44 (2000) 1±19 * Corresponding author. Tel.: ‡32-10-473710; fax: ‡33-10-473833. E-mail address: [email protected] (M. Vanclooster). 0378-3774/00/$ ± see front matter # 2000 Elsevier Science B.V. All rights reserved. PII: S 0 3 7 8 3 7 7 4 ( 9 9 ) 0 0 0 8 1 5 improving the quality of modelling datasets, and the process description of water, solute, and heat transport in a pesticide-leaching model, plus the process description of pesticide fate. Application of the principles of good modelling practice (GMP) is brie ̄y described. # 2000 Elsevier Science B.V. All rights reserved.