长期施氮和覆膜对土壤溶解性有机质含量及其结构特征的影响  

Effects of long-term film mulching and nitrogen application on soil dissolved organic matter content and structure characteristics in different soil layers

作　　者：张方方 高娜 吴锁智 白炬 李阳 岳善超[2] 李世清[2] ZHANG Fangfang;GAO Na;WU Suozhi;BAI Ju;LI Yang;YUE Shanchao;LI Shiqing(College of Life Science,Luoyang Normal University,Luoyang 471934;State Key Laboratory of Soil Erosion and Dryland Agriculture on Loess Plateau,Northwest A&F University,Yangling 712100;Wuyi Meteorological Bureau of Hengshui,Hengshui 053499;College of Resources and Environment,Shanxi Agricultural University,Taiyuan 030024)

机构地区：[1]洛阳师范学院生命科学学院,洛阳471934 [2]西北农林科技大学黄土高原土壤侵蚀与旱地农业国家重点实验室,杨凌712100 [3]河北省衡水市武邑县气象局,衡水053499 [4]山西农业大学资源环境学院,太原030024

出　　处：《环境科学学报》2023年第11期300-313,共14页Acta Scientiae Circumstantiae

基　　金：国家重点研发计划(No.2021YFD1900700);国家自然科学基金(No.42077102);洛阳师范学院高层次人才科研启动基金(No.DT2200003512)。

摘　　要：溶解性有机质(DOM)是监测土壤质量短期动态变化的重要指标.本研究基于长达12年的春玉米长期定位试验,探究了长期施氮和覆膜对0~20、20~40和40~60 cm土层土壤DOM含量和结构特征的影响,田间试验包含施氮水平和覆膜2个因子,在不覆膜和覆膜条件下设置施氮量分别为0(N0)、100(N100)、250(N250)和400(N400)kg·hm^(-2).结果表明,长期施氮显著提高了0~20和20~40 cm土层土壤溶解性有机碳(DOC)和溶解性有机氮(DON)含量,长期覆膜显著降低了0~20 cm土层土壤DOC含量,长期施氮和覆膜对各土层DOC/DON均无显著影响.无论是否覆膜,表层土壤DOC含量随施氮量呈先增加后减少趋势,在施氮量为250 kg·hm^(-2)时土壤DOC含量最高,而土壤DON含量随施氮量的增加而增加.长期施氮和覆膜均导致土壤紫外吸收曲线红移,表明长期施氮能够提高土壤DOM的共轭双键物质含量和腐殖化程度,但覆膜的作用与施氮相反.无论是否覆膜,长期施氮均能显著提高0~20和20~40 cm土层土壤DOM的SUVA_(254)、SUVA_(260)、SUVA_(280)和CDOM、CDOM/DOC,表明长期施氮提高了该土层的芳香度、疏水性、分子量和生色团浓度及相对比例.不同土层的SUVA_(254)均小于3、S_(R)均大于1、E4/E5均小于3.5,表明各土层DOM具有低芳香性、低分子量、内源性和以腐殖酸为主的特征.Pearson相关性分析结果表明,SUVA_(254)、SUVA_(260)、SUVA_(280)、CDOM、CDOM/DOC是评价土壤DOM结构组成的重要指标,而CDOM是其中的核心指标.土壤DOM及其特征光谱参数与施氮量的关系分析表明,DOC、SUVA_(254)、SUVA_(260)、SUVA_(280)、CDOM、CDOM/DOC均与施氮量在0~20和20~40 cm土层显著相关,最佳施氮量均为250 kg·hm^(-2).综上所述,无论是否覆膜,最有利于提高DOM含量和结构组成的施氮量均为250 kg·hm^(-2),且同一施氮量下,不覆膜好于覆膜.Dissolved organic matter(DOM)is an important indictor of short-term soil quality dynamics.Based on 12 years of spring maize field experiment,the effects of long-term nitrogen(N)application and film mulching on soil DOM content and its structure characteristics in 0~20,20~40 and 40~60 cm soil layers were investigated.There were two factors included in this study,namely,N application and film mulching.The N application levels were set at 0(N0),100(N100),250(N250)and 400(N400)kg·hm^(-2)under no mulching and film mulching,respectively.The results showed that long-term N application significantly increased the contents of DOC and DON in 0~20 and 20~40 cm soil layers,while long-term film mulching significantly decreased the contents of DOC in 0~20 cm soil layers.Long-term N application and film mulching had no significant effect on DOC/DON in each soil layer.Soil DOC content increased firstly and then decreased with N application rate,independently from film mulching.Soil DOC content was the highest at N application rate of 250 kg·hm^(-2),while soil DON content increased continuously with increasing N application rate.Long-term N application and film mulching resulted in redshift of soil UV absorption curve,indicating that long-term N application could increase the content of conjugated double bonds and the degree of humification of soil DOM,but the effect of film mulching was opposite to that of N application.SUVA_(254),SUVA_(260),SUVA_(280),CDOM and CDOM/DOC of DOM in 0~20 and 20~40 cm soil layers were significantly increased by long-term N application,regardless of whether the soil was mulched by a film or not.This indicates that long-term N application increased the aromatics,hydrophobicity,molecular weight,and the concentration and relative proportion of chromophores in the soil layers.The average SUVA_(254) values were less than 3,the average S_(R) values were more than 1,and the average E4/E5 values were less than 3.5,indicating that DOM in each soil layer was characterized by low aromatics,low molecular weigh

关 键 词：地膜覆盖 施氮 溶解性有机质 特征光谱参数 紫外-可见吸收光谱 

分 类 号：X833[环境科学与工程—环境工程]