Diversified crop rotation reshapes soil nutrients, microbial communities, and functions in sorghum fields

Introduction Long-term continuous sorghum cropping degrades soil environments and causes continuous cropping obstacles. This study investigated whether diversified crop rotation can maintain soil health and improve the soil microenvironment for sorghum growth. Methods Using continuous sorghum cropping as the control (SSS), three rotation systems were established: sorghum-potato-sorghum (SPS), sorghum-common vetch-sorghum (SVS), and sorghum-green pea shoots-sorghum (SGS). Soil physicochemical properties, microbial community structure and diversity were analyzed using Illumina NovaSeq high-throughput sequencing, and functional traits were predicted using FAPROTAX and FUNGuild. Mantel tests and co-occurrence network analysis were also performed. Results All three rotation treatments improved soil physicochemical properties to varying degrees, with SPS showing the greatest nutrient enhancement. SVS markedly increased bacterial richness and diversity, while SPS significantly enhanced fungal richness and diversity. β-diversity analysis revealed that rotation treatments differed significantly from SSS, with SVS and SGS showing similar bacterial structures and SPS and SVS showing similar fungal structures. Functionally important microbial groups increased in rotation soils, whereas the pathogenic genus Fusarium remained relatively high in SPS. Mantel tests indicated that soil pH, TN, TP, TK, and AK were key factors influencing microbial community structure, with AK showing the strongest correlation. Nitrogen fixation and cellulose degradation were the dominant bacterial functions, while saprotrophic and ectomycorrhizal fungi were enriched in rotation soils. Co-occurrence network analysis showed that the rotation network had higher average degree, network density, modularity, and a larger connected component than the continuous cropping network. Discussion These findings indicate that diversified crop rotation effectively elevates soil nutrient levels, reshapes microbial community structure and ecological functions, and supports high-quality and stable sorghum production.