State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China.
State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, 210008, China; University of Chinese Academy of Sciences, Beijing, 100049, China.
Environ Pollut. 2020 Feb;257:113489. doi: 10.1016/j.envpol.2019.113489. Epub 2019 Oct 31.
Ammonia emission is one of the dominant pathways of nitrogen fertilizer loss from rice fields in China. It is difficult to measure ammonia emissions by high-frequency sampling with the chamber methods widely used in China, which is of great significance for investigating the environmental effects on the ammonia emissions. The chamber methods also can not accurately determine the ammonia emissions. In this study, the backward Lagrangian stochastic dispersion model, with ammonia concentrations continuously measured by the open-path tunable diode laser absorption spectroscopy technique, was used to determine ammonia emissions from a rice field after fertilizer application at excessive (270 kg N ha) and appropriate (210 kg N ha) rates in the Taihu Lake Region of China. High temporal resolution measurements of ammonia emissions revealed that high intraday fluctuations of ammonia emissions were significantly affected by the meteorological conditions. Multiple regression analysis showed a dominant solar radiation dependence of intraday ammonia emission cycles, especially during the rice panicle formation stage. The NH-N concentrations of the surface water of the rice field were found to be the decisive factor that influenced interday dynamics of ammonia emissions. Accurate quantifications of ammonia emissions indicated that the total ammonia losses under appropriate nitrogen application rate were 27.4 kg N ha during the rice tillering stage and 11.2 kg N ha during the panicle formation stage, which were 29.4% and 17.0% less than those under traditional excessive nitrogen application rate used by the local farmers, respectively. The ammonia loss proportions during the rice panicle formation stage were significantly lower than those of the tillering stage, which might be due to different nitrogen application rates and environmental effects during the two stages. This study indicated that the open-path tunable diode laser absorption spectroscopy technique could facilitate the investigation of high temporal resolution dynamic of ammonia emissions from farmland and the environmental influence on the ammonia emissions.
氨气排放是中国稻田氮素损失的主要途径之一。中国广泛使用的气室法进行高频采样很难测量氨气排放，这对于研究氨气排放对环境的影响具有重要意义。气室法也不能准确确定氨气排放。本研究采用后向拉格朗日随机扩散模型，结合开放路径可调谐二极管激光吸收光谱技术连续测量氨气浓度，用于确定太湖地区过量（270kgNha）和适当（210kgNha）施肥后稻田的氨气排放。高时间分辨率的氨气排放测量结果表明，氨气排放的日内高强度波动受气象条件的显著影响。多元回归分析表明，日内氨排放周期与太阳辐射有明显的依赖关系，尤其是在稻穗形成阶段。稻田地表水的 NH-N 浓度被发现是影响氨排放日内动态的决定性因素。准确量化的氨排放量表明，在适当的氮肥施用量下，水稻分蘖期的总氨损失为 27.4kgNha，在穗形成期的总氨损失为 11.2kgNha，分别比当地农民传统过量氮肥用量（33.6kgNha）减少了 29.4%和 17.0%。穗形成期的氨损失比例明显低于分蘖期，这可能是由于两个阶段氮素施用量和环境效应不同所致。本研究表明，开放路径可调谐二极管激光吸收光谱技术可以促进对农田高时间分辨率动态氨排放和环境对氨排放影响的研究。
