2026-10-12T14:55:48Z https://api.figshare.com/v2/oai

oai:figshare.com:article/33990844 2026-09-24T20:16:29Z category_8 portal_316 item_type_3 month_year_09_2026

Table 2_A 20% nitrogen reduction threshold optimizes soil carbon stability and microbial functional resilience under long-term straw return in a rice–wheat rotation.docx Guohan Si (21684608) Huanqi Jiang (24868384) Chenglin Peng (21684605) Dabing Xu (18961138) Shujun Zhao (6541163) Microbiology aggregate stability carbon management index carbon sequestration metagenomics microbial carbon pump nitrogen reduction rice–wheat rotation soil organic carbon <p>Reducing synthetic nitrogen (N) fertilizer while maintaining soil fertility and crop productivity is a major challenge for sustainable rice production. Straw return has been widely adopted to enhance soil organic carbon (SOC) sequestration; however, the mechanisms by which reduced N input interacts with straw return to regulate SOC stabilization remain poorly understood. Here we evaluated graded N reduction (0, 20, and 30%) under continuous straw return in a nine-year rice-wheat double-cropping experiment in central China. Soil carbon pools, aggregate stability, organic carbon functional groups, and microbial community structure and function were assessed using carbon fractionation, wet-sieving, FTIR spectroscopy, and metagenomic analyses. We found that 20% N reduction (80%NR) maintained grain yield comparable to conventional N fertilization while significantly increasing readily oxidizable organic carbon (ROOC, +18–26%), water-soluble organic carbon (WSOC, +12–21%), microbial biomass carbon (MBC, +15–24%), and carbon management index (CMI, +42–58% relative to NR). Moderate N reduction also enhanced macroaggregate-associated SOC and the relative abundance of aliphatic and aromatic carbon functional groups. Metagenomic analyses revealed that 80%NR enriched Firmicutes (+26%), Actinobacteria (+50%), and Nitrospira, reduced methanogenic archaea, and triggered a metabolic shift from CO oxidation (coxL/cutL, −15 to −22%) toward reductive carbon fixation via the Wood–Ljungdahl pathway (hdrA2, +6 to +19%). In contrast, 30% N reduction (70%NR) undermined subsurface aggregate stability and eroded microbial functional diversity, identifying 20% N reduction as an optimal threshold within the tested gradients. These findings provide a mechanistic basis for optimizing nitrogen management in sustainable rice production systems.</p> 2026-09-24T20:16:29Z Dataset Dataset 10.3389/fmicb.2026.1928083.s002 https://figshare.com/articles/dataset/Table_2_A_20_nitrogen_reduction_threshold_optimizes_soil_carbon_stability_and_microbial_functional_resilience_under_long-term_straw_return_in_a_rice_wheat_rotation_docx/33990844 CC BY 4.0