Integrated anaerobic soil disinfestation and bio-organic fertilizers to alleviate continuous cropping obstacles: Improving soil health and changing bacterial communities

Abstract

Bacterial wilt, a soil-borne disease exacerbated by continuous cropping obstacles, poses a significant threat to tomato cultivation. Anaerobic soil disinfestation (ASD) and bio-organic fertilizers are widely employed in agricultural production due to their roles in disease suppression and soil health improvement. However, the comprehensive role and mechanism of these management strategies in remediating soil obstacle and controlling soilborne disease remain poorly understood. In this study, we simulated disturbance to the indigenous microbial community through ASD treatment, followed by the application of Bacillus subtilis and Trichoderma harzianum bio-organic fertilizers (BS and TH treatments) to restore soil microorganisms and improve soil health in a field experiment. The results showed that the combination of ASD and bio-organic fertilizers was more effective in reducing the abundance of Ralstonia solanacearum (R. solanacearum) in rhizosphere soil, lowering the incidence of tomato bacterial wilt, and increasing tomato yield compared to single ASD or bio-organic fertilizer treatments. The treatments of ASD+TH and ASD+BS significantly increased soil health index (SHI) by 31.9 % and 30.4 %, respectively. In addition, ASD+BS and ASD+TH treatments increased the abundance of B. subtilis and T. harzianum in rhizosphere soil, respectively, increased the the diversity and richness of bacterial communities, and reduced the negative correlation of bacterial communities in the co-occurrence network. Variation partitioning analysis and principal coordinate analysis revealed that ASD treatment was the primary driver of changes in bacterial community composition and structure. Microbial function prediction analysis showed that ASD combined with bio-organic fertilizers increased the relative abundance of carbohydrate metabolic pathways in the bacterial community, but decreased the relative abundance of plant pathogen function. Overall, the effective control of tomato bacterial wilt through combined ASD and bio-organic fertilizers may be attributed to the direct reduction of R. solanacearum, or to the improvement of soil health and the optimization of soil bacterial community.