| 紫色土N2O排放及氨氧化微生物群落结构对玉米秸秆与化肥减量配施的响应 |
| 摘要点击 1889 全文点击 693 投稿时间：2018-05-15 修订日期：2018-06-20 |
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| 中文关键词 秸秆还田 化肥减量 N2O 氨氧化细菌(AOB) 氨氧化古菌(AOA) |
| 英文关键词 straw return reducing fertilizer N2O bacterial ammonia oxidizer (AOB) archaeal ammonia oxidizer (AOA) |
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| 中文摘要 |
| 以紫色土为研究对象，采用静态箱-气相色谱法，通过田间原位试验，设置了对照（CK）、常规施肥（F）、秸秆与全量化肥配施（100FS）、秸秆分别与化肥减量30%（70FS）、40%（60FS）、50%（50FS）处理，观测了玉米秸秆与化肥配施下的菜地土壤N2O排放动态变化特征，并利用克隆技术和实时荧光定量PCR技术，结合土壤理化性质和氨氧化微生物amoA功能基因丰度，分析了秸秆与化肥配施对土壤N2O排放及相关微生物的影响，以期为调控和减缓紫色土N2O排放提供理论依据.结果表明，玉米秸秆与化肥配施处理较F处理提高了土壤N2O排放量和试验期内的累积排放量，其中100FS处理的N2O排放量最高[57.59~6238.02 μg·（m2·h）-1]，累积排放量高达60.76 kg·hm-2.与F处理相比，秸秆与化肥配施处理降低了土壤铵态氮和硝态氮含量，提高了土壤有机质含量，但对土壤总氮和pH值没有显著的影响.本试验条件下，土壤AOB amoA基因拷贝数比AOA高出1~2个数量级，其中F处理的AOA amoA基因拷贝数（50.9×103 copies·g-1）明显高于其他处理，但AOB amoA基因拷贝数最低（1.36×105 copies·g-1）.100FS处理降低了AOA和AOB amoA基因多样性指数和均匀度，同时也显著降低了AOA amoA基因拷贝数，但秸秆与化肥减量配施可以提高AOA和AOB amoA基因多样性，同时显著增加了AOB amoA基因拷贝数.土壤AOA优势菌群OTU1可能是硝化作用的主要驱动者，直接和间接地影响N2O排放.通过冗余（RDA）分析，土壤铵态氮、有机质和有效磷含量对AOA群落结构存在显著影响（P<0.05，蒙特卡罗算法）；土壤可溶性有机氮、总氮、速效钾以及有效磷含量显著影响AOB群落结构（P<0.05，蒙特卡罗算法），其中AOB对不同环境因子的耐受性和生态位低于AOA.总体上，玉米秸秆配施60%~70%的化肥，在保证蔬菜产量的前提下，有效提高了AOA和AOB amoA基因多样性，在一定程度上减缓了土壤N2O排放. |
| 英文摘要 |
| Crop straw is an important agricultural source, which can replace chemical fertilizers. A field experiment with six different amounts of fertilization combined with maize straw residues was carried out in purple soil, including the control (CK), conventional fertilizing (F), straw return with conventional fertilizing (100FS), straw return with 70% conventional fertilizing (70FS), straw return with 60% conventional fertilizing (60FS), and straw return with 50% regular fertilizing (50FS), to determine the response of the soil N2O emission and ammonia-oxidizing microorganism community distribution to straw return with reducing fertilizer. The dynamic characteristics of the N2O emission in purple soil were observed using an in situ closed chamber and gas chromatography-based system. The ammonia-oxidizing microorganism community distribution was analyzed with multiple molecular techniques (DNA-based clone library and qPCR) linked to physical-chemical soil properties. The results show that the combination of straw with fertilizer increases the N2O emission and cumulative N2O emission. The highest N2O emission[57.59-6238.02 μg·(m2·h)-1]and cumulative N2O emission (60.76 kg·hm-2) were observed for the 100FS treatment. Compared with the F treatment, the soil ammonium nitrogen and nitrate nitrogen contents are reduced and the soil organic matter increases after crop straw return with chemical fertilizer. However, significant changes of the soil total nitrogen and pH were not observed. The bacterial ammonia oxidizer (AOB) amoA gene abundance is higher than that of the archaeal ammonia oxidizer (AOA). The AOA amoA gene abundance during F treatment (50.9×103 copies·g-1) is significantly higher than that of others, while the AOB amoA abundance gene of the F treatment is the lowest (1.36×105 copies·g-1). The 100FS reduces the community diversity and Pielou index of AOA and AOB amoA gene. Their amoA gene abundance significantly declines during 100FS treatment. However, the increment of the AOA and AOB amoA gene diversity and dominant increment of AOB amoA gene abundance are significant when applying straw with reducing fertilizer. The specific AOA indicator OTU1 may be most important with respect to the direct and indirect production of N2O in purple soil. The redundancy analysis (RDA) shows that the community structure of AOA is remarkably relevant to the soil ammonium nitrogen, organic matter, and available phosphorus (P<0.05) and that the community structure of AOB is remarkably relevant to the soil dissolved organic nitrogen, total nitrogen, available potassium, and available phosphorus (P<0.05). The tolerance to different environments and ecological niches of AOB is weaker than that of AOA. Our results illustrate that the maize straw return with 60%-70% regular fertilizing dramatically increases the community diversity and abundance of the AOA and AOB amoA genes and partly mitigates the soil N2O emission without significantly decreasing the vegetable yields. |
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