| 生物质炭对双季稻田土壤反硝化功能微生物的影响 |
| 摘要点击 2086 全文点击 674 投稿时间：2018-10-24 修订日期：2018-12-12 |
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| 中文关键词 生物质炭 反硝化微生物 双季稻田 土壤性质 N2O排放 |
| 英文关键词 biochar denitrification microbe double rice cropping system soil properties N2O emission |
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| 中文摘要 |
| 目前，基于田间条件下生物质炭添加对稻田反硝化微生物的调控效应还不甚明确.为此，本研究采用小区试验，通过在双季稻田添加不同量的小麦秸秆生物质炭（0、24和48 t·hm-2，分别用CK、LC和HC代表），结合实时荧光定量PCR（qPCR）和末端限制性片段长度多态性（T-RFLP）分析技术，研究了生物质炭添加对双季稻田休闲季和水稻季土壤反硝化微生物相关功能基因（调控硝酸还原酶的narG基因，亚硝酸还原酶的nirK基因和氧化亚氮还原酶的nosZ基因）的影响.由于生物质炭呈碱性，添加到土壤后，可提高稻田休闲季土壤pH 0.2~0.8个单位.生物质炭本身含有部分可溶性N，因此，添加生物质炭可增加休闲季土壤铵态氮（NH4+-N）和硝态氮（NO3--N）含量，增幅分别达21.1%~32.5%和63.0%~176.0%，但由于其吸附作用，降低了水稻季NH4+-N含量48.8%~60.1%.生物质炭添加增加了休闲季微生物生物量氮（MBN）含量，这可能是由于生物质炭较大的比表面积为微生物生存提供了适宜的环境，可利用养分的增加促进了微生物的生长.与对照相比，休闲季生物质炭引起的NH4+-N和NO3--N含量增加，促进NH4+-N向NO3--N的转化，进而增加narG和nosZ的基因丰度（P<0.05），同时，生物质炭处理pH的提高促进了nosZ的基因丰度的增加，显著改变了反硝化功能基因narG和nosZ的群落结构，并以此对反硝化作用产生影响，但未对休闲季氧化亚氮（N2O）排放产生影响.而在水稻季，生物质炭增加了土壤nosZ的基因丰度（P<0.05），HC处理增加了nirK基因丰度（P<0.05），这也是导致水稻季HC处理N2O排放增加的重要原因.生物质炭通过降低水稻季土壤NH4+-N含量，改变了nirK和nosZ基因的群落结构，而narG基因群落结构的变化影响了土壤N2O排放.综上所述，生物质炭可通过改变双季稻田土壤性质，来影响参与土壤反硝化作用的相关微生物，进而影响土壤N2O排放及NO3--N的淋失. |
| 英文摘要 |
| At present, it is not explicit how biochar regulates the microbial process of denitrification in paddy fields. Therefore, a field experiment was carried out in a double rice cropping system with three wheat straw biochar treatments:no biochar treatment (CK), added 24 t·hm-2 biochar (LC), and added 48 t·hm-2 biochar (HC). Real time PCR (qPCR) and terminal-restricted fragment length polymorphism (T-RFLP) technology were adopted to analyze the abundances and microbial community structures of denitrification functional genes (narG, nirK and nosZ) in the fallow season and rice season. Due to its alkalinity, biochar amendment increased soil pH by 0.2-0.8. Biochar amendment also increased soil NH4+-N and NO3--N contents by 21.1%-32.5% and 63.0%-176.0% in the fallow season due to the presence of soluble N. Nevertheless, it reduced NH4+-N content by 48.8%-60.1% in the rice season due to the adsorption of biochar. The amendment increased soil MBN content in the fallow season, which may be a result of the large surface of biochar supplying nutrients and a suitable survival environment for the microorganisms. In the fallow season, compared to CK treatment, the increased soil NH4+-N and NO3--N with biochar amendment promoted the conversion of NH4+-N to NO3--N, and thus increased the abundances of narG and nosZ (P<0.05). The higher soil pH with biochar addition increased the abundances of nosZ and altered the community structures of narG and nosZ in the fallow season. Biochar amendment altered the denitrification process, but it did not change N2O emissions in the fallow season, which might reduce NO3--N leaching losses. In the rice season, biochar amendment increased nosZ abundance (P<0.05). HC increased the nirK gene abundance, which contributed to increased N2O emission in the rice season (P<0.05). Biochar converted the community structures of nirK and nosZ by decreasing the NH4+-N content in the rice season. The changes of the narG community structure with HC treatment contributed to the increased N2O emission. In conclusion, biochar amendment can influence the microbes involved in soil denitrification by changing the soil properties, and thus impact the N2O emissions and NO3--N leaching. |
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