Modelling herbicide treatment impact on groundwater quality in a central Italy area

A simulation study, using the MACRO-DB pesticide leaching model, was carrie d out to determine the impact of different weed control strategies on groun dwater quality in a Central Italy area (Umbria) where the drinking water we lls for the city of Perugia are located. The simulations considered nine re presentative soil profiles and two different crop rotations. Weather condit ions were those of ten years. Thirty herbicides and twenty-two weed control strategies were tested for their groundwater concentrations. Two maps repo rting the risk of groundwater contamination were made from simulations of t he two crop rotations applying the strategy with the least groundwater poll ution risk for each crop. As even the less polluting strategy in the four-c rop rotation exceeds the EU Directive 414/91 limit for drinking water, only the three-crop rotation is recommended. The present findings testify that crop selection is an effective way to minimise groundwater pollution risk.