乡村小流域不同土壤景观表土有机质团聚体分布与分子组成变化  

Changes in aggregate distribution and molecular composition of organic matter of topsoil across soil landscapes within a small watershed in a rural area

作　　者：刘纯 赵正[1,2] 刘晓雨 龙国刚[1,3] 陈硕桐[1,2] 林清美 陈敬龙 包旭华 卞荣军 郑聚锋 李恋卿[1,2] 潘根兴[1,2] LIU Chun;ZHAO Zheng;LIU Xiao-yu;LONG Guo-gang;CHEN Shuo-tong;LIN Qing-mei;CHEN Jing-long;BAO Xu-hua;BIAN Rong-jun;ZHENG Ju-feng;LI Lian-qing;PAN Gen-xing(Institute of Resource,Ecosystem and Environment of Agriculture,Nanjing Agricultural University,Nanjing,Jiangsu 210095,China;Department of Soil Science,College of Resources and Environment Sciences,Nanjing Agricultural University,Nanjing,Jiangsu 210095,China;Agro-Technical Extension Service,Jingqiao Township,Lishui District,Nanjing,Jiangsu 211224,China)

机构地区：[1]南京农业大学农业资源与生态环境研究所,江苏南京210095 [2]南京农业大学资源环境科学学院土壤学系,江苏南京210095 [3]江苏省南京市溧水区晶桥镇农业技术推广站,江苏南京211224

出　　处：《植物营养与肥料学报》2022年第5期798-811,共14页Journal of Plant Nutrition and Fertilizers

基　　金：国家自然科学基金项目(41771332)。

摘　　要：【目的】探讨丘陵山区乡村不同土壤景观表土有机质积累的团聚体分布及其化学组成的变化,为认识自然条件和人为利用下土壤有机质的空间变化特点提供新视角。【方法】选取江苏省南京市溧水区芳山小流域内保护林地、园地、旱地和稻田等景观样地,采集0—20 cm土壤样品,分析有机碳(SOC)总量。将土壤样品通过湿筛法分出宏团聚体(2000~250μm)、微团聚体(250~53μm)和粉黏粒(<53μm) 3个粒径组,测定其中有机碳含量,计算土壤中各团聚体结合态碳的比例。再者,对土壤样品依次进行总溶剂(TSE)提取,碱水解(BHY)提取和氧化铜氧化(CUO)提取,分别主要得到游离脂、结合态脂和木质素酚,采用气相色谱–质谱联用仪(GCMS)测定各组分中生物标志物有机分子丰度,计算分子多样性指数。【结果】与林地相比,园地、旱地和稻田表土本体有机碳含量分别降低70%、57%和51%,其中宏团聚体结合有机碳的含量分别降低了85%、81%和71%,微团聚体结合有机碳分别降低了74%、79%和67%,粉黏粒结合有机碳则分别降低了48%、18%和3%。表土中提取得到游离态脂类、结合态脂类和木质素酚类的有机分子丰度分别介于2.24~6.74、4.81~14.87和3.51~6.16 mg/g SOC;不同土壤景观间,这些提取态生物标志物分子丰度的变化趋势均表现为林地>稻田>园地>旱地。而木质素酚类丰度表现为林地和稻田相近。相对于林地,园地、旱地和稻田的脂肪酸丰度、烷醇、甾类及萜类等生物标志物分子丰度显著降低,但烷烃分子丰度明显增加,同时微生物来源有机质对土壤有机质的贡献提高;林地及园地土壤中结合态脂类组分以羟基酸丰度较高,而旱地和稻田则以烷酸为主。通过计算的生物标志物分子多样性指数的变化,发现游离态脂类和结合态脂类是林地和稻田高于旱地和园地,而木质素酚是稻田高于旱地,旱地又高于园地和林地。�【Objectives】We explored the changes in distribution among aggregate fractions and in chemical composition of soil organic matter of topsoil across different soil landscapes within a small watershed in a rural hilly region. This is to provide a new insight for the dynamics of soil organic carbon at different degradation levels in this region.【Methods】Undisturbed topsoil(0–15 cm) cores were sampled in protected forest land(FL),orchard(OR), dry cropland(DL) and paddy field(PF) within a small rural watershed in Lishui District, Nanjing Municipality, Jiangsu Province, China. Soil organic carbon(SOC) content was measured for bulk sample,macroaggregates(2000–250 μm), microaggregates(250–53 μm), silt-clay fraction(<53 μm). Subsequently,bulk topsoil was subject to extraction sequentially by total solvent(TSE), base hydrolysis(BHY) and cupric oxidation(CUO) to obtain free lipids, bound lipids and lignin phenols, which were analyzed for biomarker molecules abundances with GC/MS detection and Shannon diversity index. 【Results】Compared to FL, bulk topsoil SOC content in OR, DL and PF decreased by 70%, 57%, and 51%, respectively;macroaggregate SOC decreased by 85%, 81% and 71%, respectively;microaggregate SOC decreased by 74%, 79%, and 67%,respectively;silt-clay fraction SOC decreased by 48%,18%, and 3%, respectively. The range of molecular abundance of free lipids, bound lipids and lignin phenols were 2.24–6.74, 4.81–14.87 and 3.51–6.16 mg/g SOC,respectively. Across the studied soil landscapes, the total abundance of biomarker molecules in these extractions was generally in an order: FL>PF>OR>DL. Although total abundance of biomarker molecules of lignin phenols was similar between FL and PF. Furthermore, relative to FL, the molecular abundance of fatty acids, alkanols, steroids and terpenoids reduced in OR, DL and PF, while those of alkanes, contribution of microbial derived organic C and alkanols significantly increased. Of the bound lipids, there was a higher abundance of hydroxy acids in FL and O

关 键 词：土壤有机质 水稳性团聚体 土壤景观 生物标志物 分子多样性 

分 类 号：S153.621[农业科学—土壤学]