Dazomet fumigation with black film mulching improves soil microecology, reduces the abundance of antibiotic resistance genes, and increases yield of Panax notoginseng.

Continuous cropping obstacles constitute a major constraint on sustainable agricultural development, particularly in intensive cultivation of Panax notoginseng (Sanqi). Dazomet fumigation, an effective strategy for managing continuous cropping obstacles, has been widely adopted in practice. In this three-year field study, we systematically evaluated the effects of dazomet fumigation combined with black or white film on soil ecology and crop growth. The results showed that, compared with white film mulching, black film mulching after fumigation significantly accelerated dazomet degradation, shortening its half-life by 42.78%, and effectively reduced the abundance of soil-borne pathogens such as Fusarium. At harvest, compared with the white film treatment, black film increased the proportion of healthy plants by 1.35% and yield by 31.88%. Microbial analyses revealed that the black film enhanced the complexity and stability of the soil microbial co-occurrence network and enriched beneficial fungi, particularly Penicillium and Trichoderma, the relative abundance of which was positively correlated with yield of Sanqi. Furthermore, although dazomet fumigation combined with film mulching significantly increased the relative abundance of soil ARGs, black film mulching (B40) significantly decreased ARG abundance compared to white film mulching (W40). These findings provide theoretical and practical support for the green management of soil continuous cropping obstacles and sustainable production in protected agriculture.