Reduction in nitrogen fertilizer applications by the use of polymer-coated urea: effect on maize yields and environmental impacts of nitrogen losses: Nitrogen fertilizer applications via polymer-coated urea

Urea is commonly over-applied as a nitrogen (N) fertilizer to crops in southern China and has a low utilization efficiency as a result of the high precipitation and high temperatures in this region. This has led to a need to optimize the management of N fertilizer use in maize crops on the subtropical hilly uplands of southern China. RESULTS We investigated the effects of applying different amounts of N in the form of polymer-coated urea (PCU) on the yield of maize and gaseous losses of N from soils in the form of NH3 and ABO. The field plots used in this trial had zero-added N (0?kg?N?ha?1), the addition of urea (240?kg?N?ha?1) and four levels of fertilization with PCU (1 PCU, 0.9 PCU, 0.8 PCU and 0.7 PCU), which represented a 0%, 10%, 20% and 30% reduction, respectively, in the application of PCU-N relative to the urea plot. Compared to the urea plot, there was little variation in the yield of maize for all the PCU-N treatments, with a significant improvement in the utilization efficiency of N (up to 46.0?51.2%) with a 0?30% reduction in the application of PCU-N. Significant effects in the mitigation of the ABO emission flux and the accumulation of ABO-N were observed in the 0.8 PCU and 0.7 PCU plots. The application of PCU-N significantly reduced the flux and total amount of NH3-N lost to the environment: as the application rate for N decreased by 0?30%, the NH3 loss was significantly reduced by 12.7?36.1%. CONCLUSION The findings of the present study suggest that the use of PCU could allow a reduction in the application of N of 20?30% compared to traditional agricultural practices in this area with the same yield of maize, although with significantly decreased NH3 and ABO losses and the increased utilization of N. ? 2018 Society of Chemical Industry