Reducing greenhouse gas intensity using a mixture of controlled-release urea and common urea combining suitable maize...

The one-time application of common urea blended with controlled-release urea (CRU) is considered effective for improving nitrogen use efficiency and grain yield and reducing the greenhouse gas emissions of summer maize in intensive agricultural systems. However, the trade-off between the economic and environmental performances of different blended fertilizer treatments for different maize varieties remains unclear. Therefore, a consecutive two-year field experiment was conducted in the North China Plain to study the effects of different ratios of CRU and common urea on the yield, nitrous oxide (N₂O) emissions, yield-scaled total N₂O emissions, greenhouse gas intensity (GHGI), and net ecosystem economic benefit (NEEB) in 2021 and 2022. Four N fertilizer treatments with equal rate at 180 kg N ha^-1 were applied as N180U (all Urea), N180C1(1/3CRU), N180C2(2/3CRU), and N180C (all CRU), and two maize varieties (JNK728-yellow ripe variety and ZD958-green ripe variety) were used. The N180C1 and N180C2 treatments produced the highest grain yield in varieties JNK728 and ZD958 (9.4-11.5 t ha^-1 and 9.0-11.0 t ha^-1), respectively. Compared to the N180U treatment (conventional method), the N180C1 treatment reduced the GHGI (24.8 %-25.9 %) and increased the NEEB (33.1 %-33.4 %) in the JNK728 variety, whereas the N180C2 treatment reduced the GHGI (16.9 %-28.8 %) and increased the NEEB (27.2 %-48.1 %) in the ZD958 variety. The study concludes that a one-time application of blended nitrogen fertilizer in suitable varieties can minimize the GHGI and maximize the NEEB, which is an effective strategy for balancing yield and nitrogen efficiency in the summer maize system in the North China Plain.