• 关键词：外源新碳  δ¹³C  水稳性团聚体  红壤

• 基金项目：国家科技支撑计划课题（No.2014BAL01B01）；国土资源部公益性行业科研专项（No.201411008-3）；陕西省重点科技创新团队计划项目（No.2016KCT-23）

• 刘哲
• 1. 陕西省土地工程建设集团有限责任公司, 西安 710075;2. 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075;3. 中国科学院南京土壤研究所, 南京 210008

• 韩霁昌
• 1. 陕西省土地工程建设集团有限责任公司, 西安 710075;2. 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075;3. 中国科学院南京土壤研究所, 南京 210008

• 孙增慧
• 1. 陕西省土地工程建设集团有限责任公司, 西安 710075;2. 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075;3. 中国科学院南京土壤研究所, 南京 210008

• 余正洪
• 1. 陕西省土地工程建设集团有限责任公司, 西安 710075;2. 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075;3. 中国科学院南京土壤研究所, 南京 210008

• 张卫华
• 1. 陕西省土地工程建设集团有限责任公司, 西安 710075;2. 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075;3. 中国科学院南京土壤研究所, 南京 210008

• 高红贝
• 1. 陕西省土地工程建设集团有限责任公司, 西安 710075;2. 国土资源部退化及未利用土地整治工程重点实验室, 西安 710075;3. 中国科学院南京土壤研究所, 南京 210008

• 摘要：以中国科学院长期定位试验站的红壤为研究对象，通过室内模拟实验，利用δ¹³C示踪方法，将稳定同位素碳（δ¹³C）标记的水稻秸秆添加入红壤，研究水稻秸秆添加对红壤水稳性团聚体分布及稳定性的影响，探索水稻秸秆腐解过程中有机碳在不同粒级团聚体中的动态变化以及分布规律.研究结果表明：未添加水稻秸秆的红壤（对照组），微团聚体（<250 μm）占主体，>2000 μm粒级水稳性团聚体含量最少.与对照相比，添加水稻秸秆后（试验组）促进了>2000 μm粒级水稳性团聚体的团聚.不同培养时期，>2000 μm水稳性团聚体增加了108.3%~270.3%，促使大团聚体占主体，显著提高了红壤水稳性团聚体的平均重量直径（MWD）、几何平均直径（GMD）、R_0.25值，降低了分形维数（D）值，土壤结构明显得到改善.各粒级团聚体有机碳含量也显著得到提高，>2000 μm团聚体有机碳含量比对照组增加了14.7%~41.5%.土壤有机碳在>53 μm粒级团聚体中分布随着粒级的增大而增大，即 > 2000 μm > 2000~250 μm > 250~53 μm.不同粒级团聚体δ¹³C值动态变化显著，有机碳的周转速率增大.外源新碳前期主要分配在>2000 μm、250~53 μm粒级团聚体中，并促进了原有机碳的分解，后期主要分配在微团聚体中.红壤大团聚体有机碳含量与团聚体稳定性呈极显著的相关关系（p<0.01）.

• Abstract：Using isotope tracer technique of the natural ¹³C, an indoor incubation experiment of red soil incorporated with rice straw with stable isotope (δ¹³C) was carried out at the ecological experiment station of red soil, Chinese Academy of Sciences. The purpose was to study effects of application of rice straw on distribution and stability of red soil water-stable aggregates, and to explore the dynamic variation and distribution of organic carbon in soil water-stable aggregates during straw decomposition. The results showed that in red soil of no-applied rice straw, the content of microaggregates (<250 μm) was the most and that of macroaggregates (>2000 μm) was the least. Compared with the control, the application of rice straw not only promoted the formation of >2000 μm red soil waterstable aggregates by 108.3%~270.3%, but also significantly increased the mean weight diameter (MWD), geometric mean diameter (GMD) and macro-aggregate content (R_0.25) of water-table aggregates. The value of fractal dimension (D) was lower than the control, while the macroaggregates (>250 μm) became the most and soil structure improved obviously. The concentrations of organic carbon in levels of aggregates significantly (p<0.05) increased after additions of rice straw and the organic carbon in >2000 μm macroaggregates increased by 14.7%~41.5%. The storages of SOC in different size fraction aggregates increased with increasing aggregates size except for the size group of <53 μm, showing a decreasing sequence of > 2000 μm > 2000~250 μm > 250~53 μm. The dynamic variation of δ¹³C in soil water-stable aggregates changed significantly with a faster turnover rate of soil organic carbon. After 60 days of incubation, the fresh carbon supplied by rice straw was mainly found in the >2000μm and 250~53 μm fraction of soil aggregates, the native organic carbon decomposition was promoted. In the later stage, rice strraw was mainly distributed in microaggregates. The macroaggregates organic carbon and aggregate stability showed an extremely significant correlation (p<0.01).

• Key words：fresh carbon  δ¹³C  water-stable aggregates  red soil

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