Resumen
Although sewage sludge (biosolid) provides nutrients for plant growth, its successive use may result in the accumulation of heavy metals to levels detrimental to the environment. Pb behaviour in red nitosol with twice-treated contaminated sewage sludge at interval of 18 months was analysed. Soil samples received five different treatments: one with biosolid without Pb (control); two with biosolid with Pb in concentration 2,500; 5,000 µg g-1; two with Pb plus cadmium (Cd) (as interferer) in the same concentration 2,500 + 2,500 and 5,000 + 5,000 µg g-1, respectively. Pots containing the treated soil were cultivated with maize in a green house for 75 days. Pb was extracted by nitric perchloric digestion and analyzed by atomic absorption spectrometry. Soil samples with sewage sludge and contaminated by Pb presented a higher concentration of lead at 0-20 cm deep. Metal concentration remained constant in all treatments at 20-60 cm deep. Low absorption of Pb by plants was detected