Reductive soil disinfestation alleviates continuous cropping obstacles in tobacco by reshaping microbial communities...

Reductive soil disinfestation (RSD) shows potential for alleviating continuous cropping obstacles in greenhouse agriculture. However, its effects remain unclear in dryland tobacco cropping systems. A field experiment was conducted in continuous cropping tobacco fields in Bijie City, Guizhou Province. The study evaluated RSD treatments with different amounts of organic material (0, 140, and 280 kg per 667 m²) combined with a 20% reduction in chemical fertilizer. Soil physicochemical properties, microbial community structure, tobacco growth, and disease control were assessed. RSD treatments significantly increased soil pH and available nutrient levels. These improvement effects persisted until the tobacco maturation stage. RSD treatments significantly reshaped soil microbial communities, increasing fungal diversity while reducing the abundances of soil-borne pathogens such as Fusarium and Gibberella. RSD promoted the proliferation of beneficial functional groups. These included Acidobacteriota, Chloroflexi, and Bacillus. Functional predictions indicated a decline in plant pathogenic fungi. Conversely, saprophytic fungi and nitrogen-cycling bacteria functions were enhanced. The 280 kg treatment (T3) performed best, reducing bacterial wilt incidence by 93.3% and tobacco mosaic virus incidence by 76.5%, while improving leaf potassium-to-chlorine ratio. The treatment with 140 kg organic material (T2) showed weaker effects. RSD with high organic material input is an effective green strategy for managing continuous cropping obstacles in karst tobacco regions.