Ammoniated-decomposed rice straw return improves tobacco yield and reshapes the soil microbial community

Straw return with microbial agents and nitrogen fertilizer is a promising strategy for improving soil nutrient supply and productivity. However, the impact of this strategy on tobacco yield and the soil microbiome within tobacco-rice rotation systems remains unclear. A five-year field experiment was conducted to compare this integrated straw return approach, termed ammoniated-decomposed rice straw return (ADS), with conventional crushed rice straw return (CS) and rice straw removal (CK). Results showed that ADS significantly increased the five-year average tobacco yield by 7.07% compared to CK and enhanced yield stability by reducing the coefficient of variation by 21.63%. Straw incorporation primarily reshaped the fungal community, enriching key phyla such as Mortierellomycota and Basidiomycota. Functional predictions suggested that ADS reduced the relative abundance of potential plant pathogens, whereas CS increased them. Furthermore, co-occurrence network analysis revealed that ADS exhibited a higher relative abundance of module hubs in both bacterial and fungal networks. The abundance of these module hubs was significantly positively correlated with tobacco yield and soil nutrient availability in 2024. Overall, ADS represents a practical residue management strategy for tobacco-rice rotation systems. It consistently improved tobacco yield and yield stability and was associated with higher soil nutrient availability and yield-associated microbial network features. ● ADS significantly boosted tobacco yield by 7.07% and enhanced yield stability. ● Straw return shifted bacterial structure without changing bacterial richness. ● Fungal diversity and composition responded strongly; CS had the highest α-diversity. ● ADS enriched microbial network module hubs linked to higher yield and soil nutrients.