Key Laboratory of Nonpoint Source Pollution Control, Ministry of Agriculture, Institute of Agricultural Resources and Regional Planning, Chinese Academy of Agricultural Sciences, Beijing 100081, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing 210008, China.
Environ Pollut. 2018 Apr;235:482-488. doi: 10.1016/j.envpol.2017.12.103. Epub 2018 Jan 8.
Excessive nitrogen (N) fertilizers are often used in China, and a large proportion of the N can be lost as ammonia (NH). However, quantifying the NH emission from paddy fields is always affected by large uncertainties due to different measuring methods and other factors such as climate. In this study, using a standardized method, we measured the NH emissions in three typical annual rice cropping systems: single rice, double rice and rotation with other crops. The measurements were conducted for 2 years with a total of 3131 observations across China. Results showed that NH emissions accounted for 17.7% (14.4-21.0%) of the N applied under current farm practice, which was 33.1% (10.6-52.6%) higher than previous estimates. Nitrogen application rate was the dominant factor influencing NH emission rate, which exponentially increased with the N fertilizer rate (p < .001). Total NH emissions from paddy fields were estimated at 1.7 Tg N yr in 2013 in China, several times the amount of N lost through leaching or runoff. This suggests that mitigation measures for non-point source pollution from cropland should take into account not only the N lost to water, but also to air, thereby improving air quality.
过量的氮肥（N）在中国经常被使用，其中很大一部分会以氨（NH）的形式流失。然而，由于不同的测量方法和气候等因素，量化稻田的 NH 排放总是受到很大的不确定性影响。在这项研究中，我们使用标准化的方法，测量了三种典型的年度水稻种植系统中的 NH 排放：单季稻、双季稻和轮作其他作物。这 2 年的测量共在中国进行了 3131 次观测。结果表明，NH 排放占当前农业实践中施用氮的 17.7%（14.4-21.0%），比以前的估计高出 33.1%（10.6-52.6%）。氮施用量是影响 NH 排放率的主要因素，它与氮肥率呈指数增长（p<.001）。2013 年，中国稻田的总 NH 排放量估计为 1.7TgN yr，是通过淋溶或径流损失的 N 量的数倍。这表明，农田非点源污染的缓解措施不仅应考虑到流失到水中的 N，还应考虑到流失到空气中的 N，从而改善空气质量。
