Long‐Term Fertilization Regulates Greenhouse Gas Emissions Through Soil Aggregate Carbon and Nitrogen in Paddy Fields

Background and aim Rice paddies are major agricultural sources of greenhouse gases (GHG), yet it remains unclear whether regulating carbon (C) and nitrogen (N) distribution among soil aggregate fractions can mitigate emission intensity. Methods Based on a long‐term paddy‐field experiment established in 1981 in Jiangxi, China, we examined four fertilization regimes: CK (unfertilized control), NPK (mineral nitrogen, phosphorus, and potassium), DNPK (double‐rate NPK), and NPKM (NPK combined with seasonal organic amendments). Soil‐surface fluxes of methane (CH 4 ), nitrous oxide (N 2 O), and carbon dioxide (CO 2 ) were measured using static chambers, and 0–20 cm soil was fractionated into >2 mm, 0.25–2 mm, 0.053–0.25 mm, and <0.053 mm aggregates to quantify soil organic carbon (OC) and total nitrogen (TN). Global warming potential (GWP), greenhouse gas intensity (GHGI), and C/N ratio were then calculated. Results Fertilization significantly increased grain yield, with NPKM producing the highest yield (16,777.68 kg ha −1 ), followed by DNPK. DNPK generated the greatest CO 2 emissions and the highest GWP (≈6524 kg CO 2 ‐eq ha −1 ). Although DNPK and NPKM increased absolute CH 4 and N 2 O fluxes, NPKM maintained a comparatively low GHGI because of its larger yield response. NPKM increased the proportion of >2 mm macroaggregates and enhanced OC (29.19%–167.15%) and TN (42.24%–137.57%) across multiple fractions, whereas DNPK primarily increased OC in the 0.053–0.25 mm fraction. Redundancy analysis revealed that GWP was mainly driven by C/N in 0.25–2 mm aggregates, TN in >2 mm aggregates, and OC in <0.053 mm aggregates. GHGI was more sensitive to TN and OC in the 0.053–0.25 mm fraction and OC in the 0.25–2 mm fraction. Conclusion These findings suggest that long‐term integrated organic–inorganic fertilization enhances macroaggregate structure while strengthening meso‐microaggregate buffering capacity and C with N coordination. This dual mechanism sustains higher rice yields while reducing GHGI.