Tecnologia sustentável e saberes tradicionais: implicações da produção e uso agrícola de biocarvão de lodo no solo do Quilombo Serra da Guia, Sergipe

Abstract

Research inspired by traditional knowledge can provide pathways to simple and effective solutions, consistent with a model of sustainable development. The “Terra Preta de Índio” found in the Amazon is a highly fertile soil with a dark colour due to the presence of charcoal particles. It has inspired investigations into the effects of biochar use in soils. In this context, the present study aimed to investigate the implications of producing and using sewage sludge biochar (SSB) in the Serra da Guia quilombo, in Poço Redondo/SE, Brazil, by articulating sustainable technologies and traditional knowledge. Biochar can be obtained through the thermal conversion of biomass, such as the sludge generated in wastewater treatment plants, which is rich in organic matter (~45%). Aligned with the Sustainable Development Goals (SDGs), the research addresses a dual challenge faced in the Brazilian semi-arid Northeast: food insecurity in traditional communities and the need for a sustainable destination for sewage sludge, a residue with high polluting potential. To this end, an interdisciplinary quali-quantitative approach was adopted, grounded in the hypothetical-deductive method and considering the socio-environmental complexities involved. The investigation was structured into four chapters. The first chapter addresses the conversion of sewage sludge into SSB and its physicochemical characterisation, demonstrating for the first time that the process promotes pesticide degradation, as well as it favours pollutant immobilisation and preserves nutrients, thereby confirming its suitability as a safe agricultural input. The second chapter highlights the potential longevity of biochar, showing that the transformations resulting from aging in the soil maintain or even enhance its functionalities as a biofertiliser and soil conditioner. The third chapter evaluates the effects of SSB on soil water retention and the cultivation of coriander (Coriandrum sativum L.), showing significant improvements in water availability and crop development, especially with applications of 40 t ha⁻¹. Finally, the fourth chapter presents the socio-economic context and diagnosis of the quilombola family farming, based on semistructured interviews, which revealed structural vulnerabilities, female protagonism, and agricultural practices rooted in social cooperation, as well as openness to adopting technologies compatible with community values. The results indicate that SSB can contribute to strengthening family farming, enhancing soil resilience, while offering a sustainable alternative for sewage sludge management. It is emphasised, however, that its use should not be regarded as an isolated solution, but as part of a broader strategy for sustainable development that values quilombola culture, promotes socio-environmental justice, and exemplifies the principles of the circular economy, requiring integrated public policies.