Long-term impacts of straw and biochar applications on microbial diversity and soil functions in paddy soils.

The combined application of straw and biochar represents an established approach for soil improvement. However, its long-term effects on microbial diversity and soil functions remain poorly understood. In this decade-long field study, we evaluated the sustained impacts of straw and biochar amendments on microbial diversity and carbon/nitrogen-cycling functions in paddy soils. Our findings demonstrate that prolonged straw and biochar inputs increased bacterial diversity but reduced archaeal diversity. Temporal changes primarily drove this trend rather than alterations in soil parameters induced by management practices. Although bacterial diversity declined over time, potential soil functions remained stable-except for increasing nitrification potential and decreasing methanotrophy, which were primarily mediated by soil pH. Notably, annual biochar application progressively enhanced potential methanotrophy. Collectively, these results provide robust evidence for the long-term benefits of straw and biochar amendments, underscoring their critical role in maintaining microbial vitality, enhancing essential soil functions, and promoting sustained soil resilience and ecological stability.