Lysimeterversuche zum Langzeitverhalten der Herbizide Metamitron (GOLTIX$^{R}$) und Methabenzthiazuron (TRIBUNIL$^{R}$) in einer Parabraunerde mit besonderer Berücksichtigung der Transport- und Verlagerungsprozesse unter Einbeziehung von Detailuntersuchungen

The demands made on the ecological compatibility of pesticides continue to increase. The intention on the part of the legislature to promote this development has been documented in the past few years by two far-reaching amendments. In the amended German Pesticides Act (Pflanzenschutzgesetz, 1986) the natural environment ("Natural Environment : Its Components of Soil, Water, Air, Animal and Plant Species and also their Mutual Interactions") has been recognized as requiring special protection on the same level as human and animal health. In the same year, a new extremely low threshold concentration for pesticides was laid down in the Drinking Water Ordinance (Trinkwasserverordnung, 1986), which since then has also been applied to the protection of the ground water against pesticide contaminations (FEDERAL DEPARTMENT OF HEALTH (BGA), 1989, KLEIN and DIETER, 1989; KLEIN, 1987). These legal standards require a comprehensive estimate and assessment of the behaviour of pesticides and their residues in soils, which proves to be particularly difficult due to the extremely complicated interactions of soil, plant and climate factors in their impact on the processes of bonding, sorption, degradation/mineralization, translocation and volatilization. Precise knowledge of the extent and velocity of these processes and the influencing factors are necessary in order to obtain a reliable evaluation. This requires extensive study programmes taking into consideration the very different conditions of natural sites under the influence of agricultural land use. Lysimeter experiments with $^{14}$C-labelled active ingredients represent one approach (FÜHR et al., 1989 and 1991). The intellectual combination and analysis of all these results to achieve an overall assessment is a further problem as reflected in this quotation from Prof. G. Miehlich (1989) in an essay on the subject "What is Soil?", "The human brain is only capable of dealing with relationship networks to a very limited extent, and traditional training in the natural sciences promotes monocausal thinking. The system of relationships between the processes taking place within the soil and also their interactions with the entire ecosystem can be only be recognized by means of an approach considering the whole ecosystem, which has to be carried out on an interdisciplinary basis including the application of computer modelling", However, itshould be noted here that from the present point of view computer models are unable to provide accurate forecasts due to a number of simplifications and destrictions, as [...