Measures to diminish leaching of heavy metals to surface waters from agricultural soils

Historical accumulation of heavy metals in agricultural soils has caused an increased leaching to shallow groundwater in the Netherlands. The elevated concentrations of metals like copper and zinc in shallow groundwater, causes problems to meet target levels in surface waters. Important sources for metal loads to soils are manure (derived from fodder and mineral supplements), fertilisers, sulphate in disinfecting footbaths and atmospheric deposition. In general, agriculture sources are important for the total loads to surface water for cadmium, lead and zinc. Although metal contents in manure have decreased, these metals still accumulate in agricultural soils. Leaching to groundwater and surface waters will therefore continue to increase in the future. To eventually diminish these heavy metal loads to surface waters, measures at the source are necessary. To accomplish effective measures, several steps have to be taken.