Optimizing crop rotation increases soil carbon and reduces GHG emissions without sacrificing yields

Enhancing soil organic carbon (SOC) while concurrently reducing greenhouse gas (GHG) emissions and without compromising yield is a contemporary challenge for many agricultural sectors across the globe. In China, resolving the "carbon- food" nexus is a key pillar of government policies aimed at constraining “Carbon Peak” and delivering “Carbon Neutrality”. The present study explores the potential to increase SOC stocks while reducing GHGs emissions, without sacrificing crop yields considering crop rotation optimization under different irrigation managements in the North China Plain (NCP) based on a 6-year experiment. We found higher crop yields for the irrigated treatments compared with the rainfed treatments, demonstrating that rainfed crops were constrained by water deficit stress in the region. Yield was highest in the winter wheat-summer maize rotation (WM), followed by yields of the winter wheat-summer soybean (WS), while the average yields of winter wheat-summer maize-spring maize (WMMs) were lowest. SOC stocks in the surface soil (0–20 cm) increased for the irrigated treatments, but soil carbon sequestration (i.e. the rate of SOC stocks change over time) for the rainfed treatments decreased for all treatments. SOC stocks for WMMs was greatest of all treatments, leading to the highest carbon sustainability index (CSI) for this treatment. Nitrous oxide (N2O) emissions were 23–57% higher in the irrigated treatments than the rainfed treatments for the three rotations, which was highest in WMMs and lowest in WS. Carbon footprints (CFs) were highest in WS and lowest in WMMs. Overall, we found that increasing SOC stocks reduced CFs and increased yield. WMMs with irrigation was the most effective treatment for promoting SOC sequestration and mitigating GHG emissions with relatively high yield in this study, suggesting that crop rotations that are (1) more intensive and (2) grow more aboveground biomass are more likely to promulgate lower CFs and contribute towards national emissions abatement targets, such as those aimed at Net Zero.