Comprehensive tracer studies on the environmental behavior pesticides: Thelysimeter concept

The environmental behaviour of pesticides is investigated with C-14- labell ed active ingredients in lysimeter experiments simulating good agricultural practice. These microplots with an area of 0.5 to 1.0 m(2) and an undistur bed soil column of at least 1.1 m are taken from field sites representing d ifferent soil types. The C-14-labelled compounds are applied as in agricult ural practice to plants, seeds and soil. The results yield information abou t uptake and metabolism in plants, volatilization and mineralization, trans location in the soil and leaching and the status of residues in the soil. O n the basis of radioactivity and mass balances, detailed studies are design ed to contribute to the concept of studying the long-term behaviour of orga nic chemicals in the agroecosystem. The results can lead to practical recom mendations for the improved use of pesticides in general, and they are now also used as part of the registration requirements. Since all leading compa nies engaged in pesticide development now have lysimeter stations available , no new compound will be introduced into the market without already having been tested in lysimeter experiments at an early stage of development. Thi s chapter gives an introduction to the different contributions compiled in this volume.