Effect of Sewage Sludge Amended Soil on Maize Crop. II. Influence on metal accumulation

Abstract

The aim of the present study was to evaluate the influence of sewage sludge application on metal accumulation (Cu, Mn, Zn, Cd, Ni, Pb) at maize (Zea Mays L.). It was applied different doses varying from 0-600 kg/ha of sewage sludge associated with mineral fertilization. The results indicated that copper and manganese contents increase with fertilization and rates equivalent to 200 kg N/ha resulted in statistically significant copper content in the maize leaves. The highest accumulation of manganese in the leaves was recorded at the sludge rate equivalent to 300 kg N/ha, meanwhile in the maize kernels after the increasing sludge rate, the manganese content recorded a decreasing tendency. The zinc content in the maize leaves significantly increased with the increasing rate of sludge, starting with a rate equivalent to 200 kg N/ha, sewage sludge application being a promoter of zinc accumulation but without becoming excessive. As concerns the zinc content in the maize kernels, sewage sludge rates higher than 300 kg N/ha resulted in statistically assured increases. The cadmium level in the maize leaves increased directly proportional with the rate applied and the values were statistically assured at rates higher than 200 kg N/ha. The cadmium content in the maize kernels was not affected by the treatments applied, as the very low values obtained were below the detection limit of the analytical method. The lead content in the maize leaves increased under the influence of sludge fertilization, but the accumulation was generally low, all values in leaves being under 10 mg/kg and in kernels under 1 mg/kg Pb.