Experiments were conducted where pig slurry was applied to grassland that were subsequently grazed or harvested. Soils and plant were sampled to determine their copper content. Pot experiments were also performed to help analyze the results. The copper in herbage from field that received manure varied from less than 4ug/g to greater than 100ug/g (4 to 100 ppm). Different factors influenced copper content such as practices’ management, season, precipitation patterns following manure spreading and herbage composition. Copper build-up from slurry application occurred near or at the soil surface.

Lower manure application would result in lower copper concentration in soils. Conclusion on copper toxicity are not presented other than to mention that the copper coming from manure is not more toxic than mineral copper when considering the experiment done to verify the ryegrass seedlings.