Greenhouse Gas Emissions in Maize/Peanut Intercropping Under Water-Limited Semi-Arid Growing Conditions

Maize/peanut intercropping is increasingly promoted as a climate-smart strategy for enhancing resource use efficiency and reducing environmental impacts in dryland cropping systems. However, its effects on multi-gas greenhouse emissions and yield-scaled climate performance remain insufficiently understood in semi-arid regions with sandy soil. Here, a two-year field experiment was conducted in western Liaoning, Northeast China, to quantify soil CO2, CH4, and N2O fluxes, cumulative emissions, crop yield, global warming potential (GWP), and greenhouse gas intensity (GHGI) under sole maize (SM), sole peanut (SP), and two maize/peanut intercropping systems. SM produced the highest cumulative CO2 emissions, whereas SP generated the highest CH4 uptake and the highest N2O emissions. Compared with peanut monoculture, maize/peanut intercropping significantly reduced soil N2O emissions, indicating that the introduction of maize in the intercropping system provided an effective regulatory pathway for reducing N2O emissions. Peanut yields declined by approximately 47.29–49.41%, leading to total land equivalent ratio (LER) values of 0.83–0.99. Although no significant land use advantage was observed for maize/peanut intercropping at the field scale, when crop yields were taken into account for assessment, the global warming potential (GWP) and greenhouse gas emission intensity (GHGI) were lower than those of monoculture uniformity. CO2, CH4 and N2O fluxes were strongly correlated with soil temperature and moisture, underscoring the dominant role of microclimate rather than soil structure in regulating greenhouse gas (GHG) fluxes in monoculture, while in the intercropping system, the microclimate and the soil stucture together regulate the GHG fluxes. Overall, maize/peanut intercropping has the potential of reducing the climate cost per unit of production and represents a promising strategy for enhancing GHG mitigation potential in semi-arid agroecosystems.