Using half-straw return to tackle trade-offs among Grain Yield, Multiple Soil Gas Emissions, and Soil Health in Rice-Based Rotations

Sustainable intensification of rice systems requires strategies that synergize productivity, environmental, and economic goals. This study presents a comprehensive, multi-dimensional evaluation of eight rice-based cropping systems (including straw-return and diversified green manure rotations) in the Yangtze River region, China. We uniquely integrated field measurements of greenhouse gases and reactive nitrogen (N_r) species (CH₄, N₂O, NH₃, HONO) with agronomic and soil health indicators. The climate impacts were assessed using multi-temporal metrics (GTP₂₀, GTP₁₀₀). A Comprehensive Evaluation Index (CEI) quantified system-level synergies and trade-offs. The medium rate straw-return system (NPKS2) achieved the highest CEI score (0.63), representing the optimal balance among evaluated systems. A fundamental trade-off was identified: economic benefits and crop yield showed strong positive correlations with net GHG (r = 0.6 & 0.61, P ≤ 0.001) and N_r gas emissions (r = 0.54, P ≤ 0.001and r = 0.45, P ≤ 0.05, respectively), but were negatively linked to soil organic carbon (SOC) sequestration and biodiversity. This reveals an inherent conflict between short-term productivity and environmental sustainability. Critically, by including short-lived N_r species, our assessment shows that the climate impact is highly time-dependent. For instance, NH₃-induced aerosol cooling offset 8–70% of N₂O -induced warming over 20 years, but less than 0.1% over a century. We conclude that moving beyond single-gas or single-timescale assessments is essential to reveal the true costs and benefits of management practices, thereby informing strategies that are genuinely climate-smart and sustainable.