Avaliação do potencial de uso do resíduo lama concentrada de altos-fornos como fonte de zinco em cultura de arroz (Oryza sativa L.)

Abstract

This study was done in a greenhouse at the Universidade Federal Rural do Rio de Janeiro campus, and it was initiated on April, 2005 and completed on March, 2006. The objective was to verify the effects of an addition of a steelmaking waste from a zinc concentration process, to establish if the element zinc was delivered in sufficient quantity to a good plant development, and if zinc, cadmium and lead were not delivered in such quantities to turn impossibly the usage of this residue as a commercial fertilizer. It was used two soil classes Red Yellow Oxisol (horizons A and B) and a Fluvic Entisol (A horizon), sampled in Pinheiral municipality, state of Rio de Janeiro and rice (Oryza sativa, var. BRS Curinga) as indicator plant. There were applied four treatments (four doses of residue - 94; 281; 844 and 2531 kg ha-1), and a testimony, with three repetitions in casualized blocks. The soils were analyzed for zinc, lead and cadmium, before the beginning of the study, and in their phases: soluble; exchangeable; precipitated; sorbed by organic matter and, total; zinc, lead and cadmium were quantified also at 30 and 90 days of incubation. The determination of these metals in the plants were made in the roots, leaves and grain after 145 days from sow. The soil form Oxisol A horizon showed the greatest biodisponibility for all metals along the experiment. The Entisol showed biggest dry matter production, bigger accumulation of zinc, and smaller accumulation of cadmium in the plant. The soil from Oxisol B horizon had the smallest dry matter production and zinc accumulation, and bigger accumulation of lead. Zinc and lead accumulated in roots, and cadmium in leaves. By the characteristics shown in the three soils materials studied, and the toxicity levels of lead in the plants cultivated in the soil from B horizon of Oxisol, it is not recommended the utilization of this residue as a source of zinc to rice crop.