Long-term organic manure substitution enhances soil carbon stability via organically complexed iron oxides: Evidence from a 12-year field experiment

作者：Yiming Xian, Xingyu Li, Rong Huang, Jiang Liu, Ni Zeng, Shiwei Li, Changquan Wang, Bing Li · 发表于：Geoderma · 年份：2026 · DOI：10.1016/j.geoderma.2026.117825 · 被引用次数：1 · 研究领域：Iron oxide chemistry and applications、Soil Carbon and Nitrogen Dynamics、Clay minerals and soil interactions

• MAOC plays a key role in SOC stabilization promoted by organic manure substitution. • Organic manure substitution enhances iron oxide amorphization in bulk soil and MAOM. • Organically complexed Fe oxides (Fe PP ) show higher C stabilization capacity than other Fe oxides. • Co‑precipitation with Fe PP enables carbon stability without elevated greenhouse gas emissions. Organic amendments regulate soil organic carbon (SOC) and mineral-associated organic carbon (MAOC) stability by altering iron oxides. However, most sequential extraction studies for iron oxides have focused on bulk soil instead of mineral-associated organic matter (MAOM), leaving fraction-specific responses within MAOM unclear under varying substitution ratios. Here, a 12-year field experiment was conducted with four treatments including conventional fertilization (CF), 25% organic N substitution (OS25), 50% organic N substitution (OS50) and 100% organic N substitution (OS100), to investigate the responses of iron oxides and associated organic carbon in bulk soil and MAOM. Results revealed that organic manure substitution markedly increased SOC and MAOC by 8.42%–23.73%, relative to CF. The application of organic fertilizer facilitated the transformation of crystalline iron oxides into poorly crystalline forms, notably promoting the formation of organically complexed iron oxides (Fe PP ), which became the dominant iron oxide phase. Notably, Fe PP -associated organic carbon (OC PP ) exhibited a non‑linear respon...