Straw return and nitrogen fertilization regulate soil greenhouse gas emissions and global warming potential in dual...

Abundant nitrogen (N) fertilization is needed for maize (Zea mays L.) production in China because of its huge residual biomass return. However, excessive N fertilization has a negative impact on the soil ecosystem and environment, which contributes to climate change. Soil incorporation of maize residues is a well-known practice for reducing chemical N fertilization without compromising maize yield and soil fertility. Thus, residues incorporation has the capacity to minimize N fertilization uses and hence mitigate soil greenhouse gas emissions by improving plant N uptake and use efficiency. There is still a research gap regarding the effects of maize residues incorporation on maize yield, soil fertility, greenhouse gas emissions, and plant N and carbon (C) contents. Therefore, we conducted a field experiment during spring and autumn involving four different N fertilization rates (N0, N200, N250, and N300 kg N ha^-1), with and without maize residues incorporation, to evaluate grain yield, soil fertility, plant N and C contents, and greenhouse gas emissions (GHGs). Compared to N0, N fertilizer application at 300 kg N ha^-1 with residues incorporation significantly increased area-scaled global warming potential (GWP) compared to other N fertilization rates in both spring and autumn seasons, but soil nutrient contents and plant N and C contents were not statistically different from the N250 treatment. In contrast, the N recovery use efficiency (NRUE), physiological N use efficiency (PNUE), and agronomic N use efficiency (ANUE) were significantly lower in the N300 treatment than in the lower N treatment groups. Nitrous oxide (N₂O) and carbon dioxide (CO₂) fluxes, area-scaled GWP, and greenhouse gas intensity (GHGI) were significantly lower in the N200 treatment with straw incorporation than the N250 and N300 treatments of the traditional planting system. Thus, we concluded that N200 treatment with residues incorporation is optimal for improving grain yield, soil fertility, plant N uptake, and mitigating greenhouse gas emissions.