Herbicides are important for weed control but can severely impact ecosystems, causing soil and water contamination, biodiversity loss, and harm to non-target organisms. Tebuthiuron, widely used in sugarcane cultivation, is highly soluble and persistent, posing significant environmental risks. Microbial inoculation has emerged as a sustainable strategy to mitigate such damage. This study investigated the phytoremediation potential of Mucuna pruriens and Canavalia ensiformis in tebuthiuron-contaminated soils, enhanced by fungal and bacterial inoculants. Crotalaria juncea served as a bioindicator plant, and Lactuca sativa was used in ecotoxicological bioassays. During a 140-day greenhouse experiment from September 2021 to March 2022, M. pruriens showed faster growth than C. ensiformis in uncontaminated soils but was more affected by tebuthiuron. Bacterial inoculants improved M. pruriens growth under stress, while fungal inoculants mitigated tebuthiuron’s effects on C. ensiformis. C. juncea exhibited high sensitivity to tebuthiuron but grew beyond 100 cm with bacterial inoculants. Ecotoxicological assays showed that bacterial bioaugmentation significantly reduced soil toxicity. Natural attenuation further decreased tebuthiuron toxicity, and prior cultivation of M. pruriens enhanced soil detoxification. This integrated approach combining phytoremediation and bioaugmentation offers a sustainable method to degrade tebuthiuron, foster safer agriculture, and reduce environmental and health risks.

VIABILIDADE DA ATENUAÇÃO NATURAL EM SOLO DE MANEJO ORGÂNICO CONTAMINADO COM TEBUTHIURON                                                ALESSANDRA BARONI RODRIGUES NEVES¹, VICTOR HUGO CRUZ¹, BRUNO RAFAEL DE ALMEIDA MOREIRA¹, RONALDO DA SILVA VIANA¹, PAULO RENATO MATOS LOPES^{1   1} Departamento de Produção Vegetal, Faculdade de Ciências Agrárias e Tecnológicas, Universidade Estadual Paulista – Unesp, Câmpus de Dracena. Rodovia Comandante João Ribeiro de Barros, km 651, Bairro das Antas, CEP: 17900-000, Dracena, São Paulo, Brasil - alee_rodrigues06@hotmail.com; hugo.cruz@unesp.br; b.moreira@unesp.br; ronaldo.viana@unesp.br; prm.lopes@unesp.br   RESUMO: O presente trabalho visou avaliar o efeito da aplicação de diferentes doses de tebuthiuron associadas ou não à vinhaça em solo cultivado com cana-de-açúcar em sistema de manejo orgânico. Foi avaliado o efeito da atenuação natural de amostras de solo por 88 dias quanto ao metabolismo microbiano por respirometria, à comunidade microbiana por quantificação de unidades formadoras de colônias e o potencial ecotoxicológico por bioensaios com sementes de Lactuca sativa. Observou-se que a adição de vinhaça promoveu proporcional aumento na atividade microbiana, independentemente da dose de tebuthiuron presente no solo. Em consonância, houve maior presença bacteriana nas amostras com presença de vinhaça. Quanto à ecotoxicidade, a aplicação isolada do herbicida foi capaz de aumentar o efeito negativo para o organismo-teste, possivelmente pela geração de compostos intermediários mais tóxicos. Por outro lado, a presença da vinhaça no solo favoreceu a redução desse potencial ecotoxicológico, incluindo resultados de benefícios à germinação das sementes e ao desenvolvimento das plântulas. Portanto, concluiu-se que a presença de vinhaça foi o principal fator em relação a sua associação com tebuthiuron em solo de cultivo orgânico de cana-de-açúcar, revelando efeitos positivos quanto à respiração, comunidade microbiana e ecotoxicidade.   Palavras-chave: biodegradação, ecotoxicidade, herbicida, microbiota, respirometria.   FEASIBILITY OF NATURAL ATTENUATION IN ORGANIC MANAGEMENT SOIL CONTAMINATED WITH TEBUTHIURON   ABSTRACT: The present study aimed to evaluate the effect of different doses of tebuthiuron associated or not to vinasse in soil cultivated with sugarcane in organic management system. Natural attenuation of soil samples was evaluated for 88 days, regarding the microbial metabolism by respirometry, the microbial community by the quantification of colony forming units quantification and the ecotoxicological potential by bioassays with Lactuca sativa seeds. The results showed that vinasse addition promoted a proportional increase in microbial activity, regardless of tebuthiuron dose in soil. Accordingly, there was a higher bacterial presence in samples with vinasse. As for ecotoxicity, the isolated application of the herbicide was able to increase the negative effect for the test organism, possibly by the generation of more toxic intermediate compounds. On the other hand, vinasse presence favored the reduction of this ecotoxicological potential, which included results of benefits to seed germination and seedling development. Therefore, it was concluded that the vinasse presence was the main factor in relation to its association with tebuthiuron in soil of sugarcane organic management production, which revealed positive effects in respiration, microbial community, and ecotoxicity.   Keywords: biodegradation, ecotoxicity, herbicide, microbiota, respirometry.

Herbicides impact, particularly tebuthiuron (TBT), on agroecosystems and surrounding environments had been documented in scientific literature. This study investigated the hypothesis that areas exposed to TBT, a prevalent herbicide in Brazil's sugarcane crops, might harbour microbial consortia capable of degrading this compound, assessed through a Bayesian‐based colorimetric method. Soil samples from plant cane (pC), characterised by lower organic matter on the surface, and first‐cut ratoon cane (rC) fields, with higher organic matter due to crop residues deposition, were collected for analysis. Colorimetric assays with DCPIP (2,6‐Dichlorophenolindophenol) were performed with microorganisms isolated from these fields to evaluate their TBT‐degradation capacity. In an ELISA microplate, absorbance was measured at 600 nm as DCPIP is a redox indicator. Results confirmed the degradation potential of soil microbial consortia, particularly from rC samples, as evidenced by reduced absorbance relative to the control. The data deviated from the expected sigmoidal pattern, necessitating an alternative data interpretation method. A Bayesian factor estimation approach for kernel density curves of the logarithmic response ratio proved effective for handling non‐sigmoidal spectrophotometric data. The findings offered valuable insights into TBT‐degrading microorganisms and introduced an alternative analytical tool for interpreting variable data, potentially aiding in the development of bio‐based remediation strategies.