Organic–Inorganic Fertilization Sustains Crop Yields While Mitigating N 2 O and NO Emissions in Subtropical Wheat–Maize Systems

Balancing food security with fertilizer-driven climate impacts remains critical in intensive agriculture. While organic–inorganic substitution enhances soil fertility, its effects on nitrous oxide (N 2 O) and nitric oxide (NO) emissions remain uncertain. This study evaluated N 2 O/NO emissions, crop yields, and agronomic parameters in a subtropical wheat–maize rotation under four fertilization regimes: inorganic-only (NPK), manure-only (OM), and partial substitution with crop residues (CRNPK, 15%) or manure (OMNPK, 30%), all applied at 280 kg N ha −1 yr −1 . Emissions aligned with the dual Arrhenius–Michaelis–Menten kinetics and revised “hole-in-the-pipe” model. Annual direct emission factors (EF d ) for N 2 O and NO were 1.01% and 0.11%, respectively, with combined emissions (1.12%) exponentially correlated to soil nitrogen surplus ( p < 0.01). CRNPK and OMNPK reduced annual N 2 O+NO emissions by 15–154% and enhanced NUE by 10–45% compared with OM, though OMNPK emitted 1.7–2.0 times more N 2 O/NO than CRNPK. Sole OM underperformed in yield, while partial substitution—particularly with crop residues—optimized productivity while minimizing environmental risks. By integrating emission modeling and agronomic performance, this study establishes CRNPK as a novel strategy for subtropical cereal systems, reconciling high yields with low greenhouse gas emissions.