Optimized agronomic management as a double-win option for higher maize productivity and less global warming intensity: A case study of Northeastern China

Agriculture is facing great challenges toward increasing crop productivity per unit area but also reducing the global warming intensity, especially in context of the need for a higher future food supply under changing and uncertain climate. Based on 45 site-year field experimental data in rainfed areas of Northeastern China supplemented with results from the DNDC model and combined with life cycle assessment (LCA), the study reported herein evaluated the grain yield and global warming effects of optimized maize (Zea mays) agronomic management systems. In comparison with farmers' practices (FM), the improved agronomic management (OM-1), including dense planting, reduced N fertilizer rate, split fertilizer application, and subsoiling, significantly increased grain yield, nitrogen use efficiency, and net energy ratio by 23.7%, 80.9%, and 58.1%, respectively. In contrast, the global warming potential (GWP) and global warming potential intensity (GWPI) decreased by 18.8% and 34.3% based on average of research sites. Adoption of additionally improved management system (OM-2), involving OM-1 system plus denser planting and use of organic amendments, achieved even higher grain yield while further decreasing GWP and GWPI by 31.6%, 24.9%, and 42.8% relative to FM system. In addition, OM-2 system had positive effects on soil carbon sequestration at the annual rate of 250.6 kg CO2-eqha(-1) on a 20-year prospective, which is pertinent to mitigating global warming and improving soil fertility. Furthermore, negative correlation between grain yield and GWP and GWPI indicates a double-win option of obtaining higher maize productivity and reducing global warming intensity by optimizing agronomic management system.