Sugarcane Bagasse Ashes Characterization Aiming Application in Soils.

Sugarcane bagasse has been used for electric energy production in Brazil.  As result of the process, a large amounts of sugarcane bagasse ashes (SBA) are produced, which requires proper handling and disposal. The objective of the present work was to characterize physically and chemically SBA, aiming application in soil.  X-ray fluorescence, Boehm titration, infrared analysis, C^-13 nuclear magnetic resonance, scanning electron microscopy, specific surface area (BET method), x-ray diffraction, nuclear magnetic resonance of ²⁹Si, and C-CO₂ release from soil were measured. The results showed that the SBA presents: 82.2% of SiO₂, with predominance of crystalline quartz and lower concentration of microcline (potassium feldspar) (KAlSi₃O₈); 19% of total C, being mainly constituted by labile C (36%) (alkyl groups) and part of a more stable C (37%) (aryl groups); C mineralization fraction (C-CO₂) less than 1.6% in 182 days of soil incubation; predominantly basic character (pH 8.9); low surface area (39.77 m² g^-1); predominance of macro pores in the ash particles.  The results indicate that, if applied in the soil, SBA might increase C soil stock, increase pH, and might be a source of K for plants. Indeed,  the macro pores in the ash particles may improve air and water movement in the soil and could perform as habitat for soil microorganisms. Therefore, the results indicate potential use of SBA application in soil. However, studies involving application in soil and effects on different plants species should be developed.