【摘要】 为阐明暴雨条件下，川中丘陵紫色土区碳源添加对土壤可溶性有机碳(DOC)迁移的调控效应及机制，以期为坡耕地碳素流失有效防控提供科学依据。以紫色土坡耕地为研究对象，采用野外径流小区与室内分析相结合的方法，以单施化肥(CK)为对照，设置有机肥(T1)、复合微生物肥(T2)、生物炭牛粪菇渣堆肥(T3)、玉米秸秆生物炭(T4)、升级版有机肥(T5)、有机改土基质(T6) 6个碳源添加处理，开展对紫色土坡面不同坡位土壤溶解性有机碳含量变化及光谱学特性研究。研究结果表明：外源碳添加显著提升了不同坡位土壤可溶性有机碳(DOC)含量。上坡位DOC含量较对照组提升51.53%～61.34%,其中有机肥处理对土壤DOC含量的提升效应最为显著；中坡位DOC含量增幅为16.73%～65.86%,生物炭牛粪菇渣堆肥与升级版有机肥处理与CK相比分别显著增加65.86%和61.81%,且较其他处理具有显著延缓DOC向下坡迁移的效应；下坡位DOC含量在各处理间未呈现显著差异。DOC芳香化程度呈现显著空间异质性：生物炭牛粪菇渣堆肥使上坡位DOC芳香化程度提高12.63%,而玉米秸秆生物炭与有机改土基质处理则分别显著降低10.10%和16.93%;中坡位DOC芳香化程度整体呈下降趋势；下坡位生物炭牛粪菇渣堆肥处理表现出最优的芳香化提升效应，DOC芳香化程度较对照组显著提高。可溶性有机碳组分占比为：类可溶性微生物副产物>类腐殖酸>类富里酸>类色氨酸>类酪氨酸。腐殖质成分主要来源于微生物分解的内源过程，玉米秸秆生物炭与生物炭牛粪菇渣堆肥处理分别使腐殖化指数显著提升56.93%和71.84%。生物炭牛粪菇渣堆肥还田不仅能有效提升土壤可溶性有机碳含量及芳香化程度，还可显著延缓其在坡面中的迁移过程，促使DOC富集于中坡位，从而实现土壤肥力提升、碳素迁移延缓及潜在污染风险降低的多重效应。更多还原

【Abstract】 To elucidate the regulatory effects and mechanisms of carbon source addition on the migration of soil dissolved organic carbon(DOC) in purple soil areas of hilly regions in central Sichuan under heavy rainfall conditions, this study aimed to provide a scientific basis for the effective control of carbon loss in sloping farmland.Taking purple soil sloping farmland as the research object, the study employed a combination of field runoff plots and laboratory analysis.Using chemical fertilizer alone(CK) as the control, six carbon source addition treatments were established: organic fertilizer(T1), compound microbial fertilizer(T2), biochar-cattle manure-mushroom residue compost(T3), corn straw biochar(T4), upgraded organic fertilizer(T5), and organic soil amendment matrix(T6).This study investigated the changes in soil dissolved organic carbon content and spectroscopic characteristics at different slope positions.The results showed that exogenous carbon addition significantly increased the DOC content at different slope positions.The DOC content at the upper slope position increased by 51.53%–61.34% compared to the control group, with the organic fertilizer treatment showing the most significant enhancement effect.At the middle slope position, the DOC content increased by 16.73%–65.86%, with the biochar-cattle manure-mushroom residue compost and upgraded organic fertilizer treatments significantly increasing by 65.86% and 61.81%, respectively, compared to CK.These treatments also exhibited a significant delaying effect on DOC migration to the lower slope.No significant differences in DOC content were observed among treatments at the lower slope position.The degree of DOC aromatization exhibited significant spatial heterogeneity: the biochar-cattle manure-mushroom residue compost treatment increased the DOC aromatization degree by 12.63% at the upper slope position, while the corn straw biochar and organic soil amendment matrix treatments significantly reduced by 10.10% and 16.93%, respectively.At the middle slope position, the DOC aromatization degree generally showed a decreasing trend.At the lower slope position, the biochar-cattle manure-mushroom residue compost treatment demonstrated the best enhancement effect, significantly increasing the DOC aromatization degree compared to the control.The proportions of DOC components were as follows: soluble microbial byproduct-like > humic acid-like > fulvic acid-like > tryptophan-like > tyrosine-like.The humic substances primarily originated from endogenous microbial decomposition processes.The corn straw biochar and biochar-cattle manure-mushroom residue compost treatments significantly increased the humification index by 56.93% and 71.84%, respectively.The application of biochar-cattle manure-mushroom residue compost not only effectively enhanced soil DOC content and aromatization degree, but also significantly delayed its migration along the slope, promoting DOC enrichment at the middle slope position.This approach achieved multiple benefits, including improved soil fertility, delayed carbon migration, and reduced potential pollution risks.更多还原