Effects of the application of sewage sludge and petrochemical residue in maize culture as source of micro-nutrients on soils of Paraná state

Abstract

An evaluation of the potential of two organic residues as source of micro-nutrients in three soils of Paraná state was studied. Treatments consisted of one dose (38 t.ha-1) of sewage sludge and residue of purified used motor oil both neutralized with CaO+MgO mixture in 3:1 rate. Maize (Zea mays L.) was used as reference plant. After 30 days of seeding, the aerial parts of the plants were cut. They were dried at 70ºC till constant weight and ground. Analysis was undertaken after nitric-perchloric digestion. Micro-nutrients levels in the soils and in the aerial parts of the plants were determined by atomic absorption spectrometry. The results showed a production of the aerial parts of the plants treated with sewage sludge higher than those in other treatments. The micro-nutrients in Terra Roxa - TR were higher than those of Latossolo Vervelho Escuro - LE (Deep Red Latisol) and Podzólico Vermelho - PV (Red Podzolic) soils, respectively. In the aerial part of the maize plants in treated soils concentrations of micro-nutrients Cu, Fe, Mn and Zn were higher than those without treatment.Em casa de vegetação avaliou-se a potencialidade de dois resíduos orgânicos como fonte de micronutrientes em três solos do Estado do Paraná. Os tratamentos consistiram de uma dose (38 t.ha-1) de resíduo petroquímico e de lodo de esgoto neutralizados. O milho safrinha (Zea mays L.) foi utilizado como planta teste. Após 30 dias da semeadura, cortou-se a parte aérea das plantas. Estas foram secadas a 70°C, até se obter peso constante, moídas e analisadas após a digestão nitro-perclórica. Os teores de micronutrientes nos solos e nas plantas foram determinados por espectrometria de absorção atômica. Os resultados mostraram que a produção de material seco foi superior com o lodo de esgoto. Os teores de micronutrientes no solo TR (Terra Roxa) foram superiores aos dos solos LE (Latossolo Vermelho Escuro) e PV (Podzólico Vermelho), respectivamente. Na parte aérea das plantas de milho dos solos tratados as concentrações dos elementos Cu, Mn, Fe, Zn foram maiores que as do solo testemunha, com exceção do Mn no solo PV.

Keywords

• Sewage sludge
• oil residue
• environmental pollution
• micro-nutrients