Enhancing soil properties, soil-borne diseases control, and quality through selecting high C/N agricultural waste during reductive soil disinfestation for continuous tobacco cropping

The addition of organic matter is crucial for achieving successful reductive soil disinfestation (RSD) for flue-cured tobacco cultivation. However, the effects of diverse organic materials and their application rates on soil-borne disease control and yield enhancement remain poorly understood. To address this, field experiments were conducted at two sites. Two organic materials, G and D, were employed with varying application rates (CK, G/D0.8, G/D1.0, and G/D1.2). The results demonstrated that adding these organic materials enhanced soil physicochemical properties, including pH, alkaline nitrogen, available phosphorus, available potassium, organic matter, and the C/N ratio. Furthermore, the relative abundance of Phytophthora nicotianae and Fusarium spp., with associated soil-borne diseases, was significantly reduced. Particularly, the G1.2 treatment exhibited a remarkable reduction in the relative abundance of the two pathogenic bacteria by over 20% at both experimental sites. Moreover, this treatment contributed to a reduction in disease incidence by over 21% and severity by over 72%. Increasing the application rates of these organic materials also enhanced nutrient content, agronomic traits, and biomass accumulation of flue-cured tobacco plants, improving the chemical composition of tobacco leaves and economic outcomes in cured-tobacco leaves. Notably, the G1.2 treatment at both experimental sites significantly enhanced the economic indices of tobacco leaves, respectively increasing the yield and output value by 10.6 kg ha−1 and 159.9 US$·ha−1. Overall, applying 15 t ha−1 (G1.2 treatment) of solid organic material during RSD was the optimal choice for sterilization, elimination of harmful substances, and enhancement of the economic characteristics of flue-cured tobacco. •Addition of organic materials in the RSD process significantly improves soil physicochemical properties.•Adding different organic materials reduced the relative abundance of pathogenic bacteria in the soil.•Organic materials improve the nutritional composition, agronomic traits, and biomass accumulation of flue-cured tobacco.•Organic materials increase the chemical composition content and economic yield of tobacco leaves.•The use of G1.2 treatment is the best way to achieve disease control and yield increase in flue-cured tobacco.