生物炭添加对旱作农田土壤溶解性有机质及其动态影响的定位研究

Effects of Biochar on Soil Dissolved Organic Matter and Its Dynamics Studied by Located Experiment in Dryland

为揭示生物炭添加对旱作农田土壤溶解性有机质(DOM)及其动态的影响,通过定位试验,探讨了不同生物炭施用量小区土壤在2012—2017年间溶解性有机碳、溶解性无机碳和DOM的荧光光谱组分及其紫外光谱特征的变化特征。结果表明:添加生物炭总体上能够提高土壤DOC和DIC含量,且随着添加量的增加而递增。相同生物炭添加量处理中,DOC含量随施用时间增加显著降低,而DIC含量呈逐渐升高的趋势。DOM芳香化程度随施用时间延长而显著增大,施用3年后3%和5%添加量处理的芳香化程度较CK显著降低,而1%添加量处理与CK无显著差异。DOM分子量在不同施用年限之间呈增大趋势。随着生物炭添加量的增加,分子量在不同施用年限间的差异逐渐减小。土壤DOM主要由UVC类腐殖酸(C1)、UVA类腐殖酸(C2)、土壤富里酸(C3)和类色氨酸(C4)4种物质组成,其中以C1和C2为主。整体而言,除添加1%生物炭时C2随施用年限增加而降低之外,不同处理中C1及C2均随着施用年限的增加而逐渐增加,而C3和C4则显著降低。不同处理下DOM的来源以外源输入为主,微生物内源输入为辅,添加生物炭在一定程度上增强了DOM的生物可利用性。生物炭的长期施入会引起旱作农田土壤DOM组分变化,总体趋势是大分子量腐殖酸类物质在增加,而小分子量蛋白类物质在减少。

In order to reveal the effects of biochar addition on soil dissolved organic matter(DOM)and its dynamics in dryland,a located experiment was conducted to investigate the change characteristics of dissolved organic carbon(DOC),dissolved inorganic carbon(DIC)and fluorescence spectra components of DOM and its UV spectra characteristics in different soils with different biochar additions during2012to2017.The results showed that the application of biochar increased DOC and DIC contents in soil as a whole,and the contents increased with the increasing of the biochar addition amount.In the same amount of biochar treatment,the DOC content decreased significantly with the increasing of application time,while the DIC content increased gradually.The degree of DOM aromatization increase dsignificantly with the extension of application time.After three years of application,the aromatization degree of3%and5%addition amount treatments was both significantly lower than that of CK,but there was no significant difference between1%addition amount treatment and CK.The molecular weight of DOM showed an increasing trend in different application years.With the increasing of the biochar amount,the difference in the molecular weight between different application years gradually decreased.The soil DOM mainly includes four kinds of substances:UVC humic-like(C1),UVA humic-like(C2),Soil fulvic acid(C3)and Tryptophan-like(C4),of which the C1and C2components dominated.In general,except for the addition of1%biochar,the C2component decreased with the increasing of the application years,the C1and C2components in different treatments gradually increased with the increasing of the application years,while the C3and C4components decreased significantly.The fluorescence indices of soil revealed that DOM was mainly terrestrially derived rather than microbial derived.The addition of biochar enhanced the bioavailability of DOM to some extent.The long-term application of biochar could result in changes of DOM components in the dryland.The general trend was that macromolecular humic-like substances increased,while small molecular proteins-like substances decreased.