Trace element accumulation by poplars and willows used for stock fodder

Poplars and willows can accumulate high concentrations of some trace elements. We investigated the extent and nature of B, Cd, Col Cu, Fe, Mn, and Zn accumulation in some commercial poplar and willow clones by using a lysimeter experiment and field collection of data. Trace element accumulation was a function of leaf age and the variety or species of tree. Leaf B, Cd, Mn, and Zn concentrations increased throughout the season, while Cu decreased and Fe remained unchanged. Poplars and willows accumulated high concentrations of the trace elements tested, relative to pasture. The accumulation of Cd is of concern, especially in willows. Stock exposure to Cd can be managed by judicious clone selection, harvesting young shoots, or harvesting early in the season. Poplars and willows may be used as feed supplements to increase Co and Zn intake by livestock. The varieties 'Yeogi' and 'Crow's Nest' accumulated the highest concentrations of Co, yet their Cd concentrations were not significantly higher than pasture.