Humic Substance Sources on the Mobility of Residual Flubendiamide and Soil Microbial Diversity in Capsicum chinense Fields

Abstract

The persistence of pesticide residues in agricultural soils poses significant challenges to soil health, environmental safety, and crop productivity. This study investigates the influence of different humic substance sources on the mobility of residual flubendiamide and soil microbial diversity in Capsicum chinense cultivated fields. A field-based experiment was conducted in which distinct humic inputs, derived from composted organic matter, vermicompost, and commercial humic formulations, were applied to soils previously exposed to flubendiamide. The results demonstrated that humic substances significantly altered the sorption–desorption dynamics of the pesticide, thereby influencing its mobility and bioavailability. Treatments with organic-derived humic substances enhanced pesticide immobilization, reducing its potential leaching and environmental dispersion, while simultaneously improving soil physicochemical properties. In addition, these treatments promoted a marked increase in soil microbial diversity and activity, as reflected by higher microbial biomass and functional diversity indices. Enhanced microbial communities contributed to partial biodegradation of residual flubendiamide, indicating a synergistic role of humic substances in mitigating pesticide persistence. Although analytical and data-driven approaches were employed to assess microbial dynamics and residue behavior, the primary focus of the study remained on soil–plant–microbe interactions and sustainable soil management. The findings highlight the potential of humic amendments as an effective agronomic strategy to reduce pesticide risks while improving soil biological health and crop production systems. This research aligns with sustainable agricultural practices by integrating soil amendments to enhance environmental resilience and maintain agroecosystem stability.