Animal manure is a valuable source of major plant nutrients and
organic matter. However, care must be taken to ensure that manure
applications containing elevated levels of potentially toxic elements
do not lead to long-term soil contamination. In areas where animal
manure (especially pig manure) has been applied for many years
and where applications are expected to continue, it is likely that
soil heavy metal accumulation rates (including Cd) will be at their
greatest.