| 秸秆还田、地膜覆盖及施氮对冬小麦田N2O和N2排放的影响 |
| 摘要点击 1804 全文点击 511 投稿时间：2021-05-11 修订日期：2021-08-07 |
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| 中文关键词 冬小麦田 秸秆还田 覆膜栽培 氮肥 土壤N2O和N2排放 |
| 英文关键词 winter wheat straw retention film mulching nitrogen fertilizer soil N2O and N2 emissions |
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| 中文摘要 |
| 为探究不同耕作方式及施氮水平下黄土高原地区旱地冬小麦田N2O排放规律，运用静态箱-气相色谱法研究了冬小麦田N2O排放动态.以冬小麦‘小偃22’为材料，采取双因素裂区试验设计，主区为3种耕作模式：常规耕作（CT）、秸秆还田（SM）和平膜覆盖（FM）；副区为3种氮水平处理：不施氮、减氮20%（144 kg·hm-2）和常规施氮（180 kg·hm-2）.以常规耕作（CT）为对照，探讨不同施氮水平下FM和SM对土壤N2O排放产生的影响，同时分析环境因子与N2O排放通量的相关性，并根据经验公式估算N2排放量.结果表明，各施氮处理的土壤N2O的排放主要集中在施肥后20 d内，且N2O排放通量峰值出现在施肥后两周之内.冬小麦田的平均N2O通量为1.92~22.75 μg·（m2·h）-1，累积排放量为0.10~0.46 kg·hm-2；肥料氮的N2O排放系数为0.05%~0.28%，N2O全球增温潜势为26.72~122.15 kg·hm-2，N2年排放总量为0.70~1.82 kg·hm-2.施肥和覆膜可以显著提高土壤N2O排放通量（P<0.05）；SM有降低N2O排放总量的趋势.FM下的肥料氮的N2O排放系数和全球增温潜势均显著高于CT和SM（P<0.05）.不施氮处理的N2O排放只与土壤充水孔隙度（WFPS）显著正相关（P<0.05）；施氮处理的N2O排放与WFPS、ω（NO3--N）、ω（NH4+-N）和5 cm地温均呈显著正相关（P<0.05）.因此，不施肥条件下水分是控制旱地冬小麦田土壤氮素转化和N2O排放的主要因素；施肥条件下硝化作用和反硝化作用均对N2O排放有贡献.地膜覆盖和施氮显著增加了旱地N2O排放、肥料氮排放系数和全球增温潜势，秸秆还田有降低N2O排放的趋势. |
| 英文摘要 |
| In order to explore the characteristics of N2O emissions from winter wheat fields in the Loess Plateau under different farming methods and nitrogen levels, the dynamic changes in N2O emissions from rain-fed winter wheat fields were quantified using static box-gas chromatography. Winter wheat ‘Xiaoyan22’ was used as the material, and a two-factor split area design was adopted. The conventional tillage (CT), straw incorporated into soil (SM), and flat film mulching (FM) were assigned as the main plot, and three nitrogen fertilizer rates (no nitrogen fertilization, 20% nitrogen reduction (144 kg·hm-2), and conventional nitrogen application (180 kg·hm-2)) were assigned as a split plot. Taking CT as a control, the effects of FM and SM on soil N2O emissions under different nitrogen rates were assessed. Furthermore, the correlation between relevant environmental factors and N2O emission flux were analyzed, and N2 emissions were estimated using empirical formulas. The results showed the following:the N2O emissions from the soil of each nitrogen treatment occurred within 20 days, and N2O emission flux peaked within two weeks post-fertilization. The average N2O flux, the total N2O emissions, and the global warming potential of N2O were 1.92-22.75 μg·(m2·h)-1, 0.10-0.46 kg·hm-2, and 26.72-122.15 kg·hm-2, respectively. The N2O emission coefficient of fertilizer nitrogen was 0.05%-0.28%. The total N2 emissions ranged from 0.70-1.82 kg·hm-2. The N fertilization and film mulching significantly increased the N2O emission flux (P<0.05) and the cumulative N2O emissions (P<0.05); however, SM marginally reduced the total N2O emissions. The N2O emission coefficient and global warming potential of fertilizer nitrogen under FM were significantly higher than those under CT and SM (P<0.05). The N2O emissions without nitrogen treatment were only significantly positively correlated with soil water-filled pore spaces (WFPS) (P<0.05); the N2O emissions in the N fertilization condition were significantly positively correlated with WFPS, ω(NO3--N), ω(NH4+-N), and 0-5 cm soil layer temperature (P<0.05). Overall, under the condition of no fertilization, water was the main factor to control the nitrogen transformation and soil N2O emission; nevertheless, under the N fertilization condition, both nitrification and denitrification contributed to the N2O emissions in the rain-fed winter wheat fields. Film mulching practice and nitrogen application markedly increased the N2O emissions, fertilizer nitrogen emission coefficient, and global warming potential in the rain-fed winter wheat fields. Nonetheless, straw incorporated into the soil resulted in a marginal reduction in N2O emissions. |
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