Heavy metals in soils fertilized with poultry litter

The litter produced by the poultry industry is disposed of on agricultural land as a fertilizer considering its high nutrient content. Of concern, however, is the litter's heavy metal content. The possible fate of these metals in the soil include accumulation in the soil and/or plants, metal runoff in surface water and/or metal leaching through the soil profile to groundwater. The literature, however, does not contain information as to the concentration of these metals in the soil after long term land application of the litter. Soil was collected from three fields fertilized with poultry litter for over 10 years. The total metal concentrations of As, Cd, Cu, Mn, Pb and Zn in the soil were determined using a nitric acid extraction and Atomic Absorption Spectroscopy. Total As, Cu and Mn concentrations increased with litter application at all depths. Total concentrations of Cd increased within the first 10 cm of the littered soil. Lead and Zn total concentrations did not change significantly compared to those of the control fields at all depths signifying the possible operation of removal mechanisms. These results suggest the potential for As, Cu and Mn toxicity due to accumulation of these metals in the soil.