Long‐Term Biosolids Application Effects on Metal Concentrations in Soil and Bermudagrass Forage

ABSTRACT The long‐term application of biosolids that periodically contained elevated metal concentrations has raised questions about potential effects on animal health. To address these concerns, we determined metal concentrations (As, Cd, Cu, Pb, Hg, Mo, Ni, Se, and Zn) in both soil and bermudagrass [Cynodon dactylon (L.) Pers.] forage from 10 fields in the following categories of biosolids application: six or more years (>6YR), less than six years (6YR group produced forage that was at or near the MTL for Cd and Mo, and one field in the 6YR group at a proposed 5:1 Cu to Mo ratio limit to protect ruminant health. Sulfur concentrations in the forage from all three groups was near the MTL of 4 g kg−1 The study indicated that toxic levels of metals have not accumulated in the soils due to long‐term biosolids application. Overall forage quality from the biosolids‐amended fields was similar to that of commercially fertilized fields; however, due to the relatively high S and potential for a low Cu to Mo ratio, Cu supplements should be used to ensure ruminant health.