Nitrogen source and fertilizing rate are the important factors that affecting greenhouse gas emissions from cropland. In order to evaluate the potential of reduced nitrogen and combined application of different types of fertilizer to mitigate CH4 and N2O emissions, a field experiment was conducted to investigate CH4 and N2O emissions from paddy field and the relevant driving factors. Seven fertilizer treatments were applied in this experiment, including reduced nitrogen combined with increased potassium treatment (N190CF+U+K), reduced nitrogen plus topdressing urea ammonium treatment (N230CF+UA), formula fertilization treatment (N230CF+U), combined application of organic-inorganic fertilizer (N230OF+U), stability urea with dicyandiamide and hydroquinone treatment (N230UHD), urea formaldehyde treatment (N230UF) and conventional fertilization treatment (N270CF+U). The results showed that cumulative CH4 emissions from different fertilizer treatments ranged from 78.61~181.96kg/hm2. All fertilizer treatments except for N230UHD reduced CH4emissions by 32.0%~49.6% relative to the N270CF+U treatment. The reduced nitrogen plus topdressing urea ammonium treatment had the best CH4mitigation effect among all fertilizer treatments. Cumulative N2O emissions from the paddy field ranged from 0.28~0.46kg/hm2. With the exception of N230CF+UA, total N2O emissions for all fertilizer treatments were decreased by 15.4%~38.6% in comparison with conventional fertilization treatment. The combined application of organic-inorganic fertilizer showed the priority among all fertilizer treatments. Moreover, N2O emissions in paddy field were positively correlated only with the NH4+-N and NO3--N concentrations of field surface water (P<0.05). However, CH4 emissions were significantly and positively correlated with water depth and soil temperature (P<0.01), while being negatively correlated with NH4+-N value of topsoil (P<0.05). The aggregate emission of N2O and CH4in the CO2 equivalent (GWP) for the 100-year horizon of each treatment and greenhouse gas intensity (GHGI, defined as yield scaled GWP at the 100-year horizon) were also calculated. The N230UHD treatment increased GWP in the 100-year horizon, while the other treatments decreased the GWP, with a 32.2% reduction for N230UF, a 34.9% reduction for N230CF+U, a 37.2% reduction for N230OF+U, a 37.7% reduction for N190CF+U+K, a 47.9% reduction for N230CF+UA compared to N270CF+U. The N230CF+UA, N230OF+U, N230UF and N190CF+U+K treatments performed the best in reducing GHGI, and particularly the N230CF+UA and N230OF+U treatments decreased GHGI by more than 40%, may be the better agricultural practice for both trace gas mitigation and increasing crop yields.
姜珊珊, 庞炳坤, 张敬沙, 蒋静艳. 减氮及不同肥料配施对稻田CH4和N2O排放的影响[J]. 中国环境科学, 2017, 37(5): 1741-1750.
JIANG Shan-shan, PANG Bing-kun, ZHANG Jing-sha, JIANG Jing-yan. Effects of reduced nitrogen and combined application of different fertilizers on CH4and N2O emissions in paddy fields. CHINA ENVIRONMENTAL SCIENCECE, 2017, 37(5): 1741-1750.
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