From the 3rd to the 7th year after straw return, different straw-returning practices drive shifts in soil fungal community composition, functional differentiation, and the reconfiguration of community assembly processes

Introduction: In long-term straw-returning systems, a year-scale understanding of how contrasting tillage practices shape soil fungal succession and community assembly remains limited. Methods: Based on a long-term field experiment, we investigated soil fungal communities using ITS sequencing during years 3-7 after straw return (2020-2024) under farmer shallow rotary tillage (CK) and three treatments: deep ploughing return (DPR), subsoiling straw return (SSR), and no-tillage mulching return (NTR). Fungal diversity, community composition, functional guilds, and assembly pathways were evaluated by integrating functional guild assignment, co-occurrence network analysis, and null-model metrics (βNTI) with a neutral community model. Results: = 0.5132), with greater deviation under NTR. Soil microbial biomass, enzyme activities, soil organic matter, and moisture were key drivers of community shifts. Discussion: These results demonstrate that contrasting straw-returning practices regulate fungal succession through compositional turnover, functional differentiation, and assembly reconfiguration, providing insights for optimizing straw-return management and promoting sustainable cropland systems.