Copper Toxicity To Crops Resulting From Land Application Of Sewage Sludge

Sewage sludge from the town of Fergus in Ontario exhibited moderate to severe toxicity to crops grown in lysimeter and greenhouse experiments. The Fergus sludge contained large amounts of Cu, Zn and Cr and increased the concentrations of these metals, particularly of Cu and Zn, in plant materials. Other sludges which exhibited no toxicity produced similar increases in the Zn and Cr concentrations of plant materials. These findings indicated that the Fergus sludge toxicity to crops probably was due to Cu. A large build up of Cu in the roots of annual ryegrass grown on soil treated with Fergus sludge was further evidence for Cu toxicity.