Application of Blended Controlled-Release and Normal Urea with Suitable Maize Varieties to Achieve Integrated Agronomic and Environmental Impact in a High-Yielding Summer Maize System.

The use of blended controlled-release urea (CRU) with normal urea has appeared to effectively improve grain yield and nitrogen use efficiency in summer maize systems. Nevertheless, the environmental impacts based on a life cycle assessment (LCA) and the ecosystem economic benefits with different maize varieties and ratios of CRU and urea remain unclear. In our study, a consecutive two-year field experiment was designed in the North China Plain (NCP) using two nitrogen (N) rates (0 and 180 kg N ha⁻¹), four N resources (urea-N, CRU-N:urea-N = 1:2, CRU-N:urea-N = 2:1 and CRU-N), and two maize varieties (ZD958 and YH988) in 2019 and 2020. The results showed that a once-off application of basal fertilizer in N180C2 (CRU-N:urea-N = 2:1) and N180C1 (CRU-N:urea-N = 1:2) achieved high grain yields in ZD958 and YH988 (11.0–13.5 Mg ha⁻¹ and 11.3–13.2 Mg ha⁻¹), respectively. Compared to treatment N180U, treatment N180C2 reduced reactive N losses through N leaching (−34.6%), ammonia volatilization (−17.1%), and nitrous oxide emissions (−42.0%) in variety ZD958, whereas treatment N180C1 reduced reactive N losses through N leaching (−20.3%), ammonia volatilization (−13.2%), and nitrous oxide emission (−24.2%) in variety YH988. The N180C2 and N180C1 treatments achieved the lowest C footprint (267.4 and 267.9 kg CO₂ eq Mg⁻¹) for ZD958 and YH988, respectively. Furthermore, N180C2 and N180C1 achieved the highest ecosystem economic benefits for ZD958 and YH988 of 831 and 1101 $ ha⁻¹, respectively. In summary, the application of the mixture of controlled release urea and standard urea at appropriate N rates not only achieved a high grain yield but also enhanced the ecological economic benefits while mitigating the negative environmental impacts. To sum up, using the correct CRU-N management practices coordinated with suitable genetic varieties is an effective way of achieving sustainable and environmentally friendly maize production in a high-yielding summer maize system. [ABSTRACT FROM AUTHOR]