Abstract
Effective fertilizer nitrogen (N) management plays an important role in reducing the environmental problems caused by its overuse in maize production systems. The use of enhanced-efficiency N fertilizers is an effective approach to increase crop productivity and N use efficiency. However, to the best of our knowledge, there have been no associated comprehensive evaluations of the environmental impacts using a life cycle assessment (LCA) and ecosystem economic benefits (EEB). In this study, a consecutive 2-yr plot-based field experiment was conducted in Southwest China with two N fertilizer sources, blended urea (BU) containing controlled-release urea and conventional urea (CU) at a 1:1 ratio and CU only at five N rates (0, 90, 180, 270, and 360 kg N ha−1) to determine the agronomic and environmental benefits as well as the EEB of BU in maize production. The results showed that among the five N rates tested, the N180 treatment (180 kg N ha−1) showed greater potential for maintaining a high yield (8.8 Mg ha−1) and reducing environmental impacts. The use of BU resulted in higher grain yield and agronomic efficiency compared to those with CU at 180 kg N ha−1 in 2018 but not in the following year. In addition, BU significantly reduced reactive nitrogen losses through nitrous oxide emission (−27%), ammonia volatilization (−18%), and N leaching (−24%), reducing the crop environmental footprint by decreasing the global warming, acidification, and eutrophication potential by 8%–13%, 4%–9%, and 8%–22%, respectively. Furthermore, the use of BU increased economic benefits and EEB by reducing agricultural (N fertilizer; labour) and ecological costs. Compared to CU, BU improved the EEB by 68%, 39%, 29%, and 25% at N rates of 90, 180, 270, and 360 kg N ha−1, respectively. These results demonstrated that replacement of CU with BU at the N rate of 180 kg N ha−1 is an effective strategy to improve sustainability of maize production in subtropical regions of China.
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