Abstract
Excessive use of synthetic nitrogen (N) fertilizer and lower nitrogen use efficiency (NUE) are threatening the wheat production in the middle and lower reaches of Yangtze River. Excess input of N fertilizers also results in severe environmental pollution, climate change and biodiversity loss. However, the study on reasonable nitrogen application and NUE improvement with the prerequisite of stable and high yield remains unexplored. In our study, the four different levels of nitrogen were applied to find out the nitrogen threshold which could be both friendly to environment and promise the stable and high yield. The experiment was carried out in Yangzhou University (Yangzhou, China). The wheat cultivar Yangmai 23 was selected as the research material. The four nitrogen levels were as follows: 0, 189, 229.5, and 270 kg ha-1. The results showed that the grain yield under the application of 229.5 kg ha-1 N was as high as that under 270 kg ha-1 N level, with the observation of 20.3% increase in agronomic efficiency. The N2O emission of 229.5 kg ha-1 N application was as low as that of 189 kg ha-1 N, but the grain yield and agronomic efficiency were significantly higher (11.9%) under 229.5 kg ha-1 treatment than the lower one. Taken together, this indicated the nitrogen level at 229.5 kg ha-1 could be identified as the fertilizer threshold, which will be beneficial for the future fieldwork.
Highlights
Wheat is a dominant crop used for human food and livestock feed in temperate countries [1]
Compared to the HN plot, the grain yield in the MN plot was almost the same (2014/2015 growing season) or even higher (2013/2014 growing season); the N application rates (NAR) could be efficiently reduced by 15%
The wheat yields in the two growing seasons significantly decreased by 13.5% and 13.0%, respectively, when the NARs were reduced by 30% in the LN treatment, which negatively affected wheat production
Summary
Wheat is a dominant crop used for human food and livestock feed in temperate countries [1]. China is the largest wheat producer in the world, with an annual sowing area of approximately 23.4 million ha and production of 105 million tons [2]. Due to the ubiquitous utilization of synthetic nitrogen (N) fertilizer, it is easier for China to feed 22% of the world’s population using only 9% of the available arable land [3]. The high input of synthetic N fertilizer has contributed to a substantial increase in wheat production in China [4]. China has become the largest consumer of N fertilizer in the world, and over 30% of the world’s total consumption is used by China [5].
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