Assessment of potential groundwater pollution by winter wheat herbicides using MACRO-DB model.

Risk assessment of groundwater pollution has increased in importance in rec ent yeats. Few studies have been carried out to consider the impact of agro nomic management on groundwater pollution, especially in risk areas. In thi s work the risk assessment of an area near Assisi (Umbria, Italy), where dr inking water wells for the city of Perugia are located, was carried out usi ng MACRO-DB pesticide leaching model. To reduce the number of simulations o ne crop and nine representative soil profiles belonging to five subgroups w ere selected. MACRO-DB was run for all soil profiles, simulating seven stra tegies for the herbicide treatment of winter wheat over a period often cons ecutive years. Herbicide loss and average yearly concentration in the leach ate at groundwater level are reported. The herbicides producing most pollut ion to groundwater were isoproturon and MCPA. Least pollution was observed applying post-emergence low dosage, slightly persistent herbicides. However , each strategy showed a different pollution impact in each soil, indicatin g that strategies need to be chosen according to the soil type.