Coupling effects of irrigation and nitrogen on spring maize yield and greenhouse gas emissions in Northwestern China

Abstract BACKGROUND This study explored the mechanism of irrigation and nitrogen (N) coupling on spring maize yield and soil greenhouse gas (GHG) emissions, with the objective of achieving water saving, high yield and emission reduction. Field experiments were conducted to analyze the effects of multiple irrigation and N management strategies on GHG emissions and to determine the optimal balance between GHG, water conservation and grain yield. The experiments were conducted on spring maize with three irrigation levels (low, IL; medium, IM; and high, IH) and 4 N application levels (N40, N80, N120 and N160 kg N ha −1 ). RESULTS The IL treatment exhibited the lowest N 2 O and CO 2 emission fluxes and the lowest CH 4 uptake fluxes. The N40 treatment exhibited the lowest N 2 O and CO 2 emission fluxes and the highest CH 4 uptake flux. Significant positive correlations were observed among N 2 O and CO 2 emission fluxes, CH 4 uptake fluxes, and soil moisture and inorganic N content. Maize yield initially increased and then decreased with rising levels of irrigation and N management. By employing the TOPSIS method to assess yield and greenhouse effects, we identified the IMN120 treatment as optimal given that this treatment achieved the highest yield (14 686.26 kg ha −1 ) and water use efficiency (3.51 kg m −3 ) while maintaining relatively low global warming potential (573.30 kg CO2 eq ∙ ha −1 ) and GHG intensity (0.0390 kg CO2 eq ∙ kg −1 ). CONCLUSION Irrigation optimization and N management are key to reducing GHG emissions, enhancing yield, and promoting both the sustainable development of agriculture and environmental protection. © 2024 Society of Chemical Industry.