Effects of Rice Straw Incorporation on Paddy Soil Microbiome and Metabolome Throughout the Crop Growth Period

Rice straw incorporation is a paddy soil management practice that can reduce environmental pollution, mitigate soil degradation, and minimize nutrient loss. In this study, temporal shifts in soil microbial communities and metabolic profiles were investigated across three key rice growth stages—pre-planting (BS), tillering (TI), and harvest (HA)—to elucidate the ecological effects of straw incorporation. The Shannon diversity and Pielou evenness indices were significantly higher under straw incorporation than under the control at the BS and TI stages, but significantly lower at the HA stage. Straw incorporation also increased the relative abundance of key bacterial taxa, including Polaromonas sp. AER18D145, Sphingomonas sediminicola, and Thiobacillus denitrificans. Functional annotation indicated that the microbial community was mainly associated with amino acid biosynthesis and glycolysis. Metabolomic analysis revealed significant changes in steroids and their derivatives, terpenoid lipids, and carboxylic acids and their derivatives. Three metabolites—3-hexa-isoprenyl-4,5-dihydroxybenzoic acid, LysoPE (16:1(9Z)/0:0), and stachyose—differed significantly across all stages, suggesting their potential as metabolic indicators of straw incorporation. KEGG enrichment analysis identified significant alterations in arachidonic acid, purine, galactose, and pyrimidine metabolism. Redundancy analysis further revealed positive associations of LysoPE (16:1(9Z)/0:0) and stachyose with Brevundimonas sp. Root608 and Polaromonas sp. AER18D145.