Uso de biocarvão em solo arenoso reduz a lixiviação de carbono orgânico dissolvido e não de nitrato oriundo de torta de filtro de cana-de-açúcar

Abstract

The addition of filter cake in sandy textured soils has the potential to increase fertility, increase carbon and improve the chemical, physical and biological resilience of the soil. However, the rapid mineralization and subsequent leaching of carbon and No3 - generate environmental problems for the use of these materials in agricultural soils. The application of biochar has been suggested to mitigate the leaching of carbon and nutrients in agricultural soils, but there are still few studies evaluating the ability of biochar to reduce and stabilize the leaching of nutrients from natural residues. The study aimed to investigate the effect of different doses of biochar, filter cake, and a combination of filter cake + biochar, on the leaching of dissolved organic carbon (DOC) and nitrate in sandy textured soil. The treatments were: BC05 (5.0 t.ha-1 of biochar), BC010 (10.0 t.ha-1 of biochar), BC10TF30 (10 t.ha-1 of biochar + 30 t.ha-1 filter cake), TF15 (15.0 t.ha-1 of filter cake) and TF30 (30.0 t.ha-1 of filter cake). Soil columns were filled and subsequently leached with ultrapure water twice a week for 4 weeks. The concentrations of No3 - and DOC were measured in parallel with characterization through fluorescence spectroscopy with parallel factor analysis (PARAFAC) of DOC. Biochar was able to reduce the leaching of COD and No3 - from the soil, however the same did not occur when applied together with filter cake. The soil corrected with biochar retained the humic-type COD already existing in the soil, while in the filter cake treatments there was an increase in the leaching of labile components of biological origin. In summary, the application of biochar together with the filter cake was not able to reduce the leaching of No3 - and COD, but when applied alone, the biochar attenuated the leaching of these nutrients, possibly due to the stabilization of humic type C, more complex, already present in the soil.