The presence of heavy metals in sewage sludge is one of the greatest restrictions to its application in agricultural areas. This study aimed to evaluate the effects of application rates of sewage sludge of 11 consecutive years on the distribution of Ba, Cd, Cr and Pb in three layers (0-10, 10-20 and 20-40 cm) of a Typic Hapludox soil, as well as to quantify these metals in maize leaf and kernels. The experiment was conducted under field conditions, using a randomized block design with four treatments (0, 5, 10 and 20 t ha-1 sewage sludge, dry basis) with five replications. The samples of plant leaf and kernels and soil were collected 60, 68, 80, and 123 days after seedling emergence, respectively. Rates of 10 and 20 t ha-1 sewage sludge increased soil Ba, Cr and Pb concentrations in the topsoil (0-10 cm). Leaf Cd, Cr and Pb concentrations were not affected by the treatments as well as the concentrations of Ba, Cd, Cr and Pb in whole maize plants. Barium concentration in the leaves decreased with waste application. The concentrations of Cd and Pb in the maize kernels did not reach the limits for human consumption, the Cr concentration could not be evaluated and no reference value was found for Ba comparison.
Zea mays L.; biosolids; heavy metals; waste; soil pollution
