生物质炭对紫色土耕地土壤中溶解性有机物含量和组成特征的影响

Effects of biochar application on content and characteristics of dissolved organic matter in arable land of purple soil

选取位于长江上游低山丘陵区的四川盐亭石灰性紫色土和重庆忠县中性紫色土的两种典型耕地(旱地和菜地)土壤,添加0.5%~3.0%生物质炭并经过老化作用,研究生物质炭添加对土壤中可水提的溶解性有机物(DOM)性质的影响。DOM的含量与组分特征分别以溶解性有机碳(DOC)浓度和光谱学特征参数表征。结果表明,石灰性和中性紫色土旱地不添加生物质炭的对照土壤中DOM的平均含量分别为43、65 mg DOC·kg^(-1),相应菜地的对照土壤分别为110、105 mg DOC·kg^(-1);加炭后DOM含量随投加量呈非单调性变化。石灰性和中性紫色土菜地土壤DOM的芳香性和腐殖化程度明显高于旱地土壤。三维荧光光谱的平行因子分析表明,土壤DOM由两种土壤有机质源的类腐殖质组分及一种类色氨酸组分构成,菜地土壤中各组分的含量都明显高于旱地土壤,也具有更高的芳香性和腐殖化程度。综合多种光谱学分析的结果发现,加炭并经过老化后,土壤DOM的组分特征并无明显变化。

This study characterized dissolved organic matter（DOM） in two typical arable lands of calcareous and neutral purple soil（dry land and vegetable field）that is abundantly distributed in Sichuan hilly area. Effects of biochar application（at rates of 0.5%~3.0%）on the concentration and composition of soil DOM was studied after three-months of dry-wet alternate aging process. The content and compositional characteristics of DOM were characterized by the concentration of dissolved organic carbon（DOC）and spectroscopic characteristics. Results show that concentrations of DOM extracted from calcareous and neutral purple soils are 43 and 65 mg DOC·kg^-1for dry land, and 110 and105 mg DOC·kg^-1for vegetable field, respectively. Changes in DOM contents due to biochar application vary from soils. Aromaticity and the extent of humufication of DOM in the vegetable field soils are significantly higher than the dry land soils. Two humic-like components and one tryptophan-like component are identified using fluorescence excitation-emission matrix combined with parallel factor analysis（EEMsPARAFAC）. All of these components in vegetable field soils have higher intensities, aromaticity and humification degree than that of dry land soils. Biochar application pose no significant effects on the characteristics of soil DOM according to the results of spectroscopic analyses.