<b>Transition metal availabilities in soil treated with sewage sludge</b> - DOI: 10.4025/actasciagron.v26i4.1805

Abstract

This study evaluates the transition metal availabilities when applying sewage sludge in soil. The experiment was developed under field conditions in a dystrophic red latosol of average texture. The sewage sludge was obtained at Sanepar, a state company of water treatment. The experiment used randomized blocks constituted by six treatments with sewage sludge (doses: 0, 6, 20, 40, 60 and 80 t ha-1) with four repetitions and five sampling periods (0, 30, 60, 90 and 120 days after the sewage sludge incorporation). The biosolid was applied in soil by throwing and incorporated by revolving mechanically the arable layer (0-20cm). The soil received dolomite limestone in the beginning of the experiment. Soil samples were collected in the incorporation periods in order to evaluate metal elements available in the soil in different sewage sludge doses. Each sample was dried in the air and sieved in a 2mm size frame. They were homogenized and the concentrations of the elements were determined by the atomic absorption spectrometric method in the DTPA extractor solution. The application of sewage sludge showed an increase of Fe, Mn, Cu, Zn, and CTC and at the same time showed a pH reduction. The concentrations of Cd, Ni, Co, Pb and Cr were not detected, because the method detection limit was not reached. The results showed that the Fe, Mn, Cu and Zn availabilities in the soil gradually increased as increased sewage sludge doses applied and were superior to the control treatment