Agronomic, environmental, and ecosystem economic benefits of controlled-release nitrogen fertilizers for maize production in Southwest China

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.