Environmental fate of the herbicide glyphosate in the soil-plant system: Monitoring and modelling using large-scale weighing lysimeters.

Pesticide fate models are increasingly used as tools for risk assessment and registration purposes. The aim of the present research work was to assess and describe by mathematical modelling the environmental fate of the herbicide glyphosate in the presence of genetically modified (GM) soybean, as the introduction of the transgenic technology includes several new risks. Simulations and measurements indicate that the herbicide degradation process in field lysimeters was neither influenced by the cropping of GM soybean nor by repeated herbicide applications. The simulation results further indicate that glyphosate concentrations in beans of GM soybean can exceed recommended EU guideline values under commonly used herbicide treatments. The developed modelling system is a useful tool for risk assessment of GM soybean. Moreover, application of the model allows description and assessment of pesticide behaviour in various soils and plants