Produção de biomassa e fitoextração de Cu e Zn pelo capim-elefante cultivado em lodo de esgoto puro

Abstract

The presence of high concentrations of Cu and Zn in sewage sludge may limit its agricultural use as an organic fertilizer. The aim of this work was to evaluate the production of biomass and phytoextraction of Cu and Zn by elephant grass cultivated in raw sewage sludge. The experiment was carried out in a greenhouse using a randomized blocks design. The treatments corresponded to five periods of elephant grass cultivation in plots of raw sewage sludge (30, 60, 90, 120 and 150 days), with five replications. The elephant grass demonstrated high development capacity in the raw sewage sludge, despite the adverse conditions faced, such as heating of the residue and high concentration of Zn. In the 120-day period elephant grass cultivated in sewage sludge produced 33.6 t ha-1 dry mass of the aerial part. The increase of the cultivation time provided increases in Cu and Zn extraction by the plant. However, the elephant grass presented a low phytoextraction capacity of Cu and Zn of the sewage sludge, even with longer cultivations.