Nitrous Oxide and Methane Fluxes During the Maize Season Under Optimized Management in Intensive Farming Systems of the North China Plain

Addressing concerns about mitigating greenhouse gas (GHG) emissions while maintaining high grain yield requires improved management practices that achieve sustainable intensification of cereal production systems. In the North China Plain, a field experiment was conducted to measure nitrous oxide (N2O) and methane (CH4) fluxes during the maize (Zea mays L.) season under various agricultural management regimes including conventional treatment (CONT) with high N fertilizer application at a rate of 300 kg N ha(-1) and overuse of groundwater by flood irrigation, optimal fertilization 1 treatment (OPT1T), optimal fertilization 2 treatment (OPT2T), and controlled-release urea treatment (CRUT) with reduced N fertilizer application and irrigation, and a control (CK) with no N fertilizer. In contrast to CONT, balanced N fertilization treatments (OPT1T, OPT2T, and CRUT) and CK demonstrated a significant drop in cumulative N2O emission (1.70 v.s. 0.43-1.07 kg N ha(-1)), indicating that balanced N fertilization substantially reduced N2O emission. The values of the N2O emission factor were 0.42%, 0.29%, 0.32%, and 0.27% for CONT, OPT1T, OPT2T, and CRUT, respectively. Global warming potentials, which were predominantly determined by N2O emission, were estimated to be 188 kg CO2-eq ha(-1) for CK and 419-765 kg CO2-eq ha(-1) for the N fertilization treatments. Global warming potential intensity calculated by considering maize yield was significantly lower for OPT1T, OPT2T, CRUT, and CK than for CONT. Therefore, OPT1T, OPT2T, and CRUT were recommended as promising management practices for sustaining maize yield and reducing GHG emissions in the North China Plain.