Impacto dos subprodutos da industrialização do xisto sobre atributos biológicos do solo

Abstract

The impact of using oil shale byproducts in soil on biological activity is an aspect still little known. The aim of this work was to evaluate the oil shale byproducts impact on soil biological attributes. In 2010, experiments were conducted on soil Hapludalf under laboratory conditions and field. In the laboratory, the treatments consisted of seven different rates (0, 300, 450, 600, 750, 1500 and 3000 kg ha-1) of oil shale ash (OSA), calcareous of shale (CS) and fragments of shale (FS). In the field, in two crops of beans (Phaseolus vulgaris L.) in notillage system, the treatments were composed of the OAS, with four rates (0, 750, 1,500 and 3,000 kg ha-1) in combination with mineral fertilizer (NPK) and one treatment with only a single rate of OSA (1,500 kg ha-1). Other control treatment was beans cultivated without OSA and without NPK. The evaluations were: CO2 evolution, microbial biomass carbon (MBC), soil enzyme activity (acid phosphatase, arylsulfatase, β-glucosidase, urease, fluorescein diacetate hydrolysis, dehydrogenase) and ecotoxicological test. In the laboratory study, the data show a low degradability of organic fraction of solid byproducts of the oil shale industrialization. The application of the OAS reduces CO2 emissions without reducing the CBM. The OSA does not cause negative impacts on soil enzymatic activity even when reapplied to the soil at increasing rates. The results obtained with the enzymes activity under field conditions after two applications of OAS, combined with the results of MBC, the metabolic quotient (qCO2) and ecotoxicological test indicate that the solid byproducts of the oil shale industrialization (OSA, CS and FS) does not cause the biological degradation of soil.