none A concept is presented to evaluate pesticides in soil-plant systems and in sections of agro-ecosystems, using ecochemical data obtained from standardized, closed and controlled ventilated cultivating chambers. These consist of special constructed cultivating containers and attachments for ad- and absorption of portions of volatile organic compounds and the degradation product 14C-CO-2 which is formed from a pesticide due to mineralization of the radiolabeled compound. A balance account can be obtained from a pesticide's distribution pattern in various compartments after application of the 14C-labeled compound on the plants or on the soil towards the end of the experiments. Important points on the metabolism of a pesticide are included. The efficiency and limits of using the closed cultivating systems is shown with an example of foliar spray application of 14C-dichlofluanid (Euparen) used to control fungal diseases on fruits of strawberries. A further development of the closed cultivating container led to development of a closed, controlled ventilated vegetation chamber. This may accommodate a section of an agro-ecosystem, providing the possibility to determine the pathway and fate of a chemical quantitatively in parts of the food-chains present in the section of the agro-ecosystem. Because of the size of the vegetation chamber it is necessary that a large air flow through the chamber is guaranteed which is 60 air-exchanges/h. The outlet air leaving the chamber is split into a ratio 1:10. From these constant and defined air flows the 14CO-2 liberated as a mineralization product of the test chemical is absorbed from the smaller part and determined quantitatively. Considering the air split ratio it is possible to determine quantitatively 14CO-2 along with the other organic volatile components. By utilizing a section of the agro-ecosystem cabbage field with the central parasite-beneficial relationship, Pieris brassicae (large cabbage butterfly) and Apanteles glomeratus (wasp of large cabbage butterfly) the fate of 14C-monolinuron was determined. This was followed quantitatively in different trophic levels of the model section of the agro-ecosystem to establish the suitability of the chamber system and to derive the ecochemical and ecotoxicological data.