Effects of different remediation agents on soil herbicides, microbial community structure and tobacco leaf quality

Atrazine and quinclorac are commonly used herbicides in flue-cured tobacco preceding crops in Southwest China. Their residues often damage subsequent tobacco crops, seriously affecting their normal growth and development. Soil remediation could directly or indirectly regulate the degradation of herbicides by affecting soil physicochemical properties and soil microbial community activity. In this study, we analyzed the degradation characteristics of two high-risk herbicides in local tobacco soil and their effects on tobacco growth and development through a field trial in Bijie Guizhou, Southwest China. We applied three different soil remediations (biochar, quicklime, and shell powder) at the same dosage of 1.5 t/ha. The results show:the growth potential of tobacco in the biochar treatment was the best, with the degradation rate of atrazine reaching 90.22% and that of quinclorac reaching 69.10%. All remediations improved the structure and diversity of the soil bacterial community. The biochar treatment significantly enhanced the regulatory and restoration capacity of the soil microbial environment. Moreover, both biochar and lime have positive effects on improving the soil microbial environment of tobacco fields contaminated by herbicides, providing theoretical and practical guidance for controlling herbicide residues, enhancing tobacco quality and safety, and achieving sustainable production in tobacco fields.