Zinc availability for corn grown on an oxisol amended with flue dust

Abstract

The costs related to the construction and maintenance of industrial landfills, and the environmental risks that they may represent, have increased the interest of several types of industries in studying the possibility of applying residues to agricultural soils. This study evaluates the efficiency of flue dust as a zinc source for corn, and the zinc availability for corn evaluated by four methods. A greenhouse experiment carried out at Campinas, SP, Brazil, evaluated the effect of two zinc sources (flue dust and zinc sulphate), at three rates (5, 50 and 150 mg dm -3 ), in one soil (Rhodic Hapludox) under two pH conditions (5.0 and 6.0). The treatments were arranged in a randomized factorial scheme design with three replications. Zinc availability indexes were determined by the pH 7.3 DTPA, Mehlich-1, and Mehlich-3 methods. The free Zn 2+ activity in soil solution was calculated by the MINTEQ computer model. The extraction methods and the activity of the free ion Zn 2+ were equally reliable to evaluate zinc availability in the soil amended with flue dust. More than 70% of the total Zn present in the saturation extract was in the free ion form, and the remainder was mainly complexed to SO 4 2-and OH -, independent of soil pH. Flue dust is a zinc supplier to plants. All tested methods were efficient in evaluating Zn availability for corn, independently of soil pH. ) e um solo (Latossolo Vermelho) com dois valores de pH (5,0 e 6,0). Os tratamentos foram distribuídos em esquema fatorial com três repetições. A disponibilidade de zinco foi determinada por DTPA pH 7.3, Mehlich-1 e Mehlich-3 e a atividade do Zn 2+ livre na solução do solo foi calculada pelo modelo MINTEQ. Nos dois valores de pH estudados, tanto a atividade do Zn 2+ como os três métodos de extração foram igualmente eficientes em avaliar a disponibilidade de zinco para as plantas em solos tratados com pó de aciaria. Mais que 70% do Zn total presente no extrato de saturação estava como íon livre e o restante complexado com SO 42-e OH -, independente do pH do solo. O pó de aciaria é uma fonte de zinco para as plantas. Todos os métodos testados foram eficientes em estimar a disponibilidade de Zn para o milho, independente do pH. Palavras-chave: DTPA, metal pesado, resíduo industrial, especiação, pH do solo