• 关键词：水旱轮作  N₂O排放  油菜季  施肥  环境因子

• 基金项目：中央高校基本科研业务费专项资金（No.2662016PY098）

• 徐鹏
• 华中农业大学资源与环境学院, 武汉 430070

• 蒋梦蝶
• 华中农业大学资源与环境学院, 武汉 430070

• 邬磊
• 华中农业大学资源与环境学院, 武汉 430070

• 吴限
• 华中农业大学资源与环境学院, 武汉 430070

• 赵劲松
• 华中农业大学资源与环境学院, 武汉 430070

• 胡荣桂
• 1. 华中农业大学资源与环境学院, 武汉 430070;2. 华中农业大学环境生态中心, 武汉 430070

• 摘要：设置了水稻季与油菜季均不施用氮肥（N_0-0）；水稻季施用氮肥150 kg·hm^-2（以N计，下同），油菜季不施用氮肥（N_150-0）；水稻季与油菜季均施用氮肥150 kg·hm^-2（N_150-150）；水稻季不施用氮肥，油菜季施用氮肥150 kg·hm^-2（N_0-150）4种施肥处理，采用静态箱/气相色谱法对旱作油菜季N₂O的排放进行了原位观测（2016年9月-2017年4月），研究了华中地区水旱轮作模式下水稻季施肥对油菜季土壤N₂O排放的影响.结果表明，油菜季N₂O排放主要集中在施基肥后1周内.N_0-0、N_150-0、N_150-150和N_0-150处理N₂O排放通量变化范围分别为-10.81~181.26、-20.48~95.61、-8.87~638.56和-21.76~827.86 μg·m^-2·h^-1，平均排放通量分别为4.58、3.89、21.06和27.24 μg·m^-2·h^-1，N₂O累积排放量分别为0.20、0.17、0.92和1.19 kg·hm^-2，施氮肥处理（N_150-150和N_0-150）N₂O排放量显著高于不施氮肥处理（N_0-0、N_150-0）（p<0.05）.N_150-150和N_0-150处理N₂O排放通量与土壤孔隙充水率（WFPS）具有显著正相关关系（p<0.05）；N_150-150和N_0-150处理N₂O排放通量与土壤可溶性有机氮（DON）和无机氮（NO₃^--N和NH₄⁺-N）具有显著正相关关系（p<0.01）.以上结果表明，油菜季N₂O排放与稻季施用氮肥无关，施氮肥对土壤活性氮含量的影响是导致N₂O排放差异的主要原因，而土壤孔隙充水率也是影响油菜季N₂O排放的重要环境因子.

• Abstract：Farmland is a main source of nitrous oxide (N₂O) which is an important greenhouse gas next to carbon dioxide (CO₂) and methane (CH₄), but the effects of agricultural measures on N₂O emission are unclear. To study the effects of nitrogen fertilization during rice growing season on N₂O emission from the subsequent rapeseed season in central China, a static/gas chromatography method was used by situ observation with no nitrogen fertilizer in two seasons (N_0-0); nitrogen fertilizer of 150 kg·hm^-2 in rice season and no nitrogen fertilizer in rapeseed season (N_150-0); nitrogen fertilizer of 150 kg·hm^-2 in each season (N_150-150) and no nitrogen fertilizer in rice season and nitrogen fertilizer of 150 kg·hm^-2 in rapeseed season (N_0-150) four kinds of fertilization carried out in a long-term fertilization experiment platform (between September 2016 and April 2017). The results showed that N₂O emissions mainly concentrated within 1 week after basal dressing. N₂O fluxes from treatments of N_0-0,N_150-0,N_150-150 and N_0-150 varied from-10.81~181.26,-20.48~95.61,-8.87~638.56 and-21.76~827.86 μg·m^-2·h^-1, with average fluxes of 4.58, 3.89, 21.06 and 27.24 μg·m^-2·h^-1 and cumulative emissions were 0.20, 0.17, 0.92 and 1.19 kg·hm^-2, respectively. Cumulative N₂O emissions of nitrogen treatments were significantly higher than no nitrogen treatments (p<0.05). N₂O fluxes from N_150-150 and N_0-150 treatments both had a significant positive correlation (p<0.05) with soil water filled pore space (WFPS) and a very significant positive correlation (p<0.01) with soil dissolved organic nitrogen(DON) and inorganic nitrogen. The above results showed that the differences of reactive nitrogen content resulted from nitrogen fertilization in soil is the key to soil N₂O emissions and the water filled pore space is also a important environmental factor affecting N₂O emissions.

• Key words：paddy rice-upland crop rotation  N₂O emission  rapeseed season  fertilization  factors

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