Influence of nitrogen fertilizer application on maize yield and nitrogen use efficiency in China

Maize (Zea mays L.) is a staple crop in China however, the excessive application of nitrogen fertilizer by farmers beyond crop requirement has led to a reduction in nitrogen use efficiency and environmental problems. To better understand these problems, we explored the differences in maize nitrogen management in China, this study uses a two-season field experiment conducted to test the effect of nitrogen rate on maize growth, yield, and NUE at Quzhou Experimental Station in the North China Plain in 2020-2021. The main results are shown below: Field experiment results indicated that the application of 200 kg N/ha led to a higher yield of 7685 kg/ha in 2021, while the application of 60 kg N/ha resulted in higher N use efficiency. Excessive application of N led to reduced Partial Factor Productivity (PFPN) and Agronomic Use Efficiency (AEN) when 200kg N/ha was applied compared to the application of 60 kg N/ha with a PFPN of 33.1 kg/kg and 128.1 kg/kg, respectively, in 2021. In summary, the high application of nitrogen has been found to increase yield, however, the excessive application beyond crop requirement for maximum maize yield led to low partial factor productivity and agronomy use efficiency of N. Therefore, it is paramount to reduce nitrogen application rate as the application beyond the optimal rate does not guarantee a steady increase in yield but rather causes a decline in nitrogen utilization of maize. Overall, the result indicates that for China to sustain maize production and improve N use efficiency, application rate needs to be optimized.