强还原处理和生物炭对设施蔬菜土壤DOM数量和光谱特征的影响

土壤强还原处理（Reductive Soil Disinfestation，RSD）可以有效地修复设施蔬菜土壤的连作障碍，但实施过程中亦会引起可溶性有机质（Dissolved Organic Matter，DOM）数量和质量的变化.本研究通过培养实验，设置未修复对照（CK）、RSD修复（RSD）、生物炭修复（BC）及RSD与生物炭联合修复（RSD+BC）4个处理，对比研究不同修复处理对土壤DOM含量和光谱特征的影响.结果表明，与CK相比，RSD、BC和RSD+BC修复后土壤的DOC含量分别增加了142.9%、24.6%和127.0%；相较于RSD处理，RSD+BC处理的DOC含量显著降低（p<0.05）.土壤DOM组分以类富里酸和类腐殖酸物质为主，RSD处理增加了类腐殖酸组分，而RSD+BC处理更有利于类富里酸物质的增加.RSD、BC及二者联合修复显著增强了土壤DOM的芳香化和腐殖化程度.结构方程模型分析表明，土壤pH对DOC含量和腐殖化指数（HIX_em）产生直接正效应，土壤氧化还原电位（E_h）对DOC含量具有直接负效应，pH亦可通过影响DOC含量间接影响微生物量碳（MBC）和荧光指数（FI）.

Effects of reductive soil disinfestation and biochar on the quantity and spectral characteristics of dissolved organic matter in facility vegetable soil

Reductive soil disinfestation (RSD) is an effective management practice to restore degraded facility vegetable soil. However, the quantity and quality of dissolved organic matter (DOM) is also changed during the implementation of RSD, and there is a risk of DOM leaching. In this study, four treatments, i.e., soil without any organic material application as control (CK), soil with 2% (w/w) rice straw (RSD), soil with 2% (w/w) biochar (BC) and soil with 2% (w/w) rice straw and 2% (w/w) biochar (RSD+BC), were performed to compare their influences on the content and spectral characteristics of soil DOM. Results indicated that the contents of DOC in RSD, BC and RSD+BC treatments were increased by 142.9%, 24.6% and 127.0% in relation to CK. Compare with the RSD treatment, the RSD+BC treatment significantly reduced the DOC content (p<0.05). Soil DOM was mainly composed of fulvic acid-like and humic acid-like material, and RSD treatment improved the humic acid-like component, whereas RSD+BC treatment was more conductive to the increase of fulvic acid-like substances. RSD, BC and RSD+BC treatments significantly enhanced the degree of aromatization and humification of soil DOM. Structural equation model analysis also showed that soil pH had a direct positive effect on DOC content and humification index (HIX_em) and E_h had a direct negative effect on DOC content. Meanwhile, soil pH also indirectly affect microbial biomass carbon (MBC) and fluorescence index (FI) due to DOC change.