| 生物质炭对双季稻水稻土微生物生物量碳、氮及可溶性有机碳氮的影响 |
| 摘要点击 2099 全文点击 643 投稿时间：2019-01-22 修订日期：2019-02-21 |
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| 中文关键词 生物质炭 水稻土 双季稻 微生物生物量碳、氮 可溶性有机碳、氮 |
| 英文关键词 biochar paddy soils double rice cropping system microbial biomass carbon, nitrogen dissolved organic carbon, nitrogen |
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| 中文摘要 |
| 生物质炭可影响土壤微生物量，但生物质炭对双季稻田土壤微生物生物量碳、氮（MBC、MBN）及可溶性有机碳、氮（DOC、DON）的影响还不清楚.基于此，本研究选取亚热带2种典型双季稻田土壤（花岗岩母质发育的水稻土S1和第四纪红壤发育的水稻土S2）作为研究对象，开展室内培养试验来研究不施氮肥条件下生物质炭添加对土壤微生物生物量碳、氮及可溶性有机碳、氮的影响.每种土壤设置3个小麦秸秆生物质炭添加量，即土重的0%、1%和2%，分别用CK、LB和HB表示.培养70 d后，2种水稻土的MBC均值：S1为877.03、832.11和849.30 mg·kg-1，S2为902.94、874.19和883.22 mg·kg-1.S1+LB、S1+HB和S2+LB均显著降低了土壤MBC均值（P<0.05），这可能是由生物质炭吸附土壤有机碳及其他有机物，阻碍了微生物的生长而造成的.S1土壤中低生物质炭添加量较对照显著降低了土壤MBN均值（P<0.05），降幅达9.45%.生物质炭对S1土壤MBC/MBN均值影响不明显，但LB降低了S2土壤MBC/MBN均值（P<0.05）.由于生物质炭本身含有部分可溶性有机碳及其高pH值，添加到2种水稻土中均增加了土壤DOC均值，增幅分别达4.42%~22.20%和10.57%~35.47%.但生物质炭（除S2+HB处理）显著降低了土壤DON均值，这可能归因于生物质炭对土壤有机氮的吸附作用及生物质炭本身有机碳分解过程中对N的消耗作用.生物质炭显著增加了2种水稻土的DOC/DON均值，且随着生物质炭添加量的增加而增加.综上所述，在双季稻田土壤中单施生物质炭虽然可增加土壤可溶性有机碳，但对土壤微生物量有一定的降低作用，且会加重土壤氮亏缺状况.因此，在亚热带双季稻田中生物质炭应与化肥等配合施用. |
| 英文摘要 |
| Biochar can influence soil microbial biomass. It is not clear how biochar amendment affects soil microbial biomass carbon and nitrogen (MBC and MBN) and dissolved organic carbon and nitrogen (DOC and DON) in double-cropping rice soils. To address this problem, two subtropical double-cropping rice soils (S1 and S2) were selected for an incubation experiment. S1 is developed from granite-weathered red soil and S2 is developed from Quaternary red clay. The following three wheat straw-derived biochar application rates were used, without N fertilizer, in each paddy soil:0%, 1%, and 2% of soil weight, represented by CK, LB, and HB, respectively. After a 70 d incubation, soil mean MBC was 877.03 mg·kg-1, 832.11 mg·kg-1, and 849.30 mg·kg-1 in S1 for the three application rates, and 902.94 mg·kg-1, 874.19 mg·kg-1, and 883.22 mg·kg-1, respectively, in S2. S1+LB, S1+HB, and S2+LB treatments reduced soil mean MBC compared to the CK treatment (P<0.05). This may be attributed to biochar inhibiting microbial growth by adsorbing soil organic carbon and other low-molecular-weight organic matter. Low biochar application rates decreased mean soil MBN by 9.45% compared to the CK treatment in S1 (P<0.05). No significant differences in mean MBC/MBN were observed among the S1 treatments, but LB reduced MBC/MBN in S2 (P<0.05). Due to the soluble organic carbon content and strong alkalinity of biochar, biochar amendment increased mean soil DOC by 4.42%-22.20% and 10.57%-35.47% in S1 and S2, respectively (P<0.05). However, biochar amendment (except for the S2+HB treatment) decreased mean soil DON in both paddy soils. This may have resulted from the adsorption of soil organic nitrogen by biochar and N consumption during the decomposition of the organic carbon within biochar. Biochar amendment increased mean soil DOC/DON in both paddy soils (P<0.05) and mean DOC/DON increased with an increase in the biochar application rate. Based on these results, biochar amendment increased soil dissolved organic carbon, decreased soil microbial biomass, and enhanced the nitrogen deficit in double-cropping paddy soils. Therefore, biochar should be combined with the application with fertilizer in double-cropping rice systems in subtropical central China. |
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