The development of focus scenarios for assessing pesticide leaching to groundwater in EU registration

A workgroup established under FOCUS (FOrum for Go-ordination of pesticide f ate models and their USe) has chosen nine scenarios as representative of th e range of climatic and soil conditions in agriculture regions in the EU wh ere groundwater recharge occurs. These scenarios, to be used in initial eva luations for Annex listing under the Directive 91/414/EEC, are considered t o be reasonable worst cases (approximately 90(th) percentile) with the vuln erability split evenly between soil and weather properties. The workgroup h as identified 26 crops as representative of EU agriculture, and agronomic p arameters for those crops appropriate to each scenario have been obtained. The MARS database has been used to provide 20 years of weather data for eac h scenario. Computer shells containing the weather data, soil properties, c rop parameters, acid irrigation schedules have been developed for three mod els (PELMO, PESTLA, and PRZM) and for one of the nine scenarios also for th e MACRO model. User input is limited to providing information on pesticide properties and application. All model shells provide pesticide concentratio ns leaching below 1 m depth averaged over periods of one, two or three cale ndar years. Some models also provide averages at greater depths when approp riate soil and pesticide information are available. The scenarios will beco me available during the course of 2000.