Caracterização de biocarvão de lodo de esgoto e bagaço de cana-de-açúcar e efeitos no cultivo de beterraba

Abstract

The objectives of the study were to characterize biochars produced from sewage sludge (BSS) and sewage sludge mixed with sugarcane bagasse (BBSS) and to evaluate the effects on soil chemical properties and production and nutrition mineral of beets plants. The biochars were producing through pyrolysis process on 450º C. The experiment was conducted in greenhouse of the ICA / UFMG, from July to October 2015, in a completely randomized design, with seven treatments and five repetitions, corresponding to increasing levels of BBSS 0; 2.5; 5; 7.5 to 10% (volume / volume) and two controls: mineral fertilizer (NPK) and intermediate dose BL (5%). All the treatments with biochar had reactive phosphate "Bayovar" addition. The soil used was a Yellow Oxisol of low natural fertility. Initially, the soil with their respective treatments with biochar and natural phosphate were incubated for a period of 45 days in pots of 4 dm-3 capacity. The same process was adopted for treatment with mineral fertilizer, incubated only with corrective of soil acidity. After incubation, beet seedlings produced in commercial substrate were transplanted and cultured for 55 days. Soil samples were collected from each pot after 45 days of incubation and after 55 days of transplanting the seedlings. The biochars and soil were analyzed for nutrient content, Cr, Cd and Pb, physical fractionation of organic matter and 13C isotopic composition. Beets plants were divided into aerial part, tuberous roots and fine roots for the determination of dry matter and nutrient content, Cr, Cd and Pb. The nutrients contents, Cd and Pb of biochars were below the limits established by Brazilian legislation. The addition of sugarcane bagasse to sewage sludge increased the yield and quality of biochar. The application of biochars had corrective effect on the components of soil acidity, increased nutrient availability, soil organic carbon and change the isotopic composition of the soil. BBL doses increased the dry mass of beets plants and favored the production of fine roots. The contents of Fe, Mn, P, Mg in the plants for all treatments were above adequate reference values, but there was not symptoms of phytotoxicity. On the other hand, the Pb and Cd contents were below the detection limit. In this way, biochar had a positive effect in improving the chemical properties of soil and sugar beet productivity; it can be considered as proper waste management evaluated.