中文关键词氮素秸秆还田激发效应长期施肥同位素 英文关键词nitrogenstraw returningpriming effectlong-term fertilizationisotope

作者	单位	E-mail
徐学池	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 中国科学院大学, 北京 100049 中国科学院环江喀斯特农业生态试验站, 环江 547100	xuxuechi16@mails.ucas.ac.cn
苏以荣	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
王桂红	贵州大学农学院, 贵阳 550025
刘坤平	中国科学院环江喀斯特农业生态试验站, 环江 547100
胡亚军	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
陈香碧	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125
郑小东	武汉市水产发展有限公司, 武汉农业集团, 武汉 430014
何寻阳	中国科学院亚热带农业生态研究所, 亚热带农业生态过程重点实验室, 长沙 410125 中国科学院环江喀斯特农业生态试验站, 环江 547100	hbhpjhn@isa.ac.cn

中文摘要 秸秆还田配施氮肥是调控农田土壤有机碳转化的重要措施，为认知秸秆配施氮肥对秸秆和长期施肥土壤有机碳矿化的作用机制，选取喀斯特长期施肥定位试验3种土壤（不施肥、无机肥、秸秆与无机肥配施），采用室内培养结合¹³C示踪技术，设置不添加秸秆（对照组）及添加秸秆配施3种氮素水平处理（0、214.0和571.0 mg·kg^-1，以干基土计），研究¹³C标记的秸秆和土壤有机碳的矿化及其机制.结果表明，长期施肥土壤的秸秆CO₂排放量均显著高于不施肥土壤，且氮素水平显著影响不施肥土壤的秸秆有机碳矿化；长期施肥土壤激发效应均显著低于不施肥土壤，且低水平氮素配施降低秸秆添加引起的正激发效应，高水平氮素反而增大.PCA分析表明长期施肥、秸秆还田配施氮肥均显著改变土壤微生物群落，其中秸秆与氮素配施显著增加土壤总PLFAs、细菌和真菌PLFA摩尔质量浓度（与对照相比，增幅分别为40.3%~53.0%、41.1%~62.6%和60.5%~148.6%），但氮素水平影响不显著，土壤G⁺/G^-降低并稳定在0.8左右.结构方程模型结果表明，秸秆还田配施氮肥增加土壤DOC含量、影响土壤革兰氏菌群落结构，从而影响秸秆和土壤有机碳矿化.上述结果表明秸秆还田配施低水平氮肥有利于提升喀斯特农田土壤固碳能力. 英文摘要 The use of straw returning plus nitrogen fertilizer on farmland is one of the important agronomic practices for adjusting soil organic carbon (SOC) transformations. To explore the mechanisms of straw and nitrogen fertilizer application on straw and SOC mineralization in long-term fertilized soils, an incubation experiment with the ¹³C isotope tracing technique was conducted, which involved three long-term fertilized models in typical karst soils (no fertilization, inorganic fertilization, and a combination of inorganic fertilization and straw). To study the mechanisms of ¹³C-labeled straw and SOC mineralization, four treatments were designed as follows:no straw and nitrogen (control), and straw combined with three levels of nitrogen fertilizer (0, 214.0, and 571.0 mg·kg^-1 soil). The results showed that cumulative mineralization amounts of straw-derived organic carbon in long-term fertilized soils were markedly higher than those in non-fertilized soil. Straw-derived organic carbon mineralization was significantly affected by nitrogen fertilizer levels. The positive priming effects (PE) in long-term fertilized soils were much lower than those in non-fertilized soil. The PE was decreased at the low nitrogen fertilizer level but increased at the high nitrogen fertilizer level. The principal component analysis (PCA) of phospholipid fatty acids (PLFAs) indicated that the soil microbial community structure was greatly affected by the long-term fertilization models and combined straw and nitrogen fertilizer application. Moreover, the content of PLFAs in soil microorganisms, namely, bacteria and fungi, were remarkably increased by the straw plus nitrogen fertilizer (values increased by 40.3%-53.0%, 41.1%-62.6%, and 60.5%-148.6% compared with control), but levels were not significantly affected by nitrogen fertilizer levels alone. The ratios between PLFAs of soil gram-positive and gram-negative bacteria (G⁺/G^-) decreased and were stable at around 0.8. The structure equation models (SEM) demonstrated that the combination of straw and nitrogen affected the soil gram-positive and gram-negative bacteria structure and increased the soil DOC content, which promoted the decomposition of straw and affected the mineralization of SOC. These results indicate that straw returning plus low nitrogen fertilizer can improve the SOC sequestration capacity in karst farmland.

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