Balancing Maize Yield, Greenhouse Gas Emissions, and Soil Functions Through Nitrogen Fertilizer Reduction and Microbial Network Regulation

Excessive nitrogen (N) fertilization accelerates agricultural greenhouse gas (GHG) emissions and leads to soil degradation, yet the potential of reduced N inputs to balance crop yield, GHG emissions, and soil multifunctionality—and the underlying mechanisms—remains unclear. Through a 2‐year field experiment, we found that a 25% reduction in N fertilizer (R25) reshaped the soil microbial co‐occurrence network, resulting in a topology with higher connectivity (avgK) and shorter path distances (GD) compared to conventional fertilization (CF, 200 kg ha −1 ). This restructuring increased the abundance of functional microbes associated with aromatic compound degradation, aerobic ammonia oxidation, and nitrification, thereby maintaining soil carbon and nitrogen cycling capacity and sustaining crop productivity. Mechanistically, the enhanced microbial network facilitated more efficient nutrient transformation and transfer, leading to a 30.66%–32.94% increase in nitrogen use efficiency (NUE) and a 13.87%–35.72% reduction in greenhouse gas intensity (GHGI). In contrast, a 50% N reduction (R50) restricted nutrient availability and decreased yield by 10.08%–11.10%. Partial least squares path modeling revealed that N‐induced changes in soil multifunctionality were primarily driven by microbial network topology. Our findings identify an optimal N reduction range of 22.50%–34.00% (132–155 kg ha −1 ) for sustaining maize yield and soil multifunctionality while reducing GHGI, highlighting the regulation of microbial network as a key strategy for sustainable maize production.