Biochar influences the cane fields’ microbiota and the development of pre-sprouted sugarcane seedlings

This research investigates the soil conditioning effect of sugar cane fields with biochar produced from sugarcane bagasse. Its influence on the physicochemical and microbiological conditions of the soil and the agronomic performance of sugarcane seedlings was verified. To this end, the biochar from sugarcane bagasse was produced by pyrolysis in a double drum oven and mixed with soil at rates of 0, 1%, 3%, and 5% (in weight). The experiment was installed in a greenhouse with two evaluation periods (30 days and 60 days) and five replicates. Each pot received a pre-sprouted cane seedling, and the analysis of colony-forming units (bacteria and fungi), physicochemical characteristics of the soil, and growth and development of sugarcane were performed per pot. The biochar showed a high fixed carbon content (72%) and a specific surface area estimated by the adsorption of methylene blue of 50 m² g⁻¹. Furthermore, its structure is porous and contains important nutrients (e.g., CaO, K₂O, and P₂O₅). In the periods evaluated, the applications of the 3% and 5% (in weight) rates of biochar reduced most of the soil fertility parameters. However, the chemical analyses indicated that the sugarcane field soil collected already possessed high fertility. The microbiota was influenced, but only the application of the 3% (in weight) rate at 60 days after planting showed a significant positive effect on the number of bacteria forming units, with an increase of approximately 385%. On the other hand, no significant positive effect on sugarcane development was found. Therefore, biochar application in high-fertility sugarcane plantation soil did not result in gains for sugarcane development in the periods evaluated.