Are humic substances soil microbial residues or unique synthesized compounds?A perspective on their distinctiveness  

作　　者：Sen DOU Jun SHAN Xiangyun SONG Rui CAO Meng WU Chenglin LI Song GUAN 

机构地区：[1]College of Resources and Environmental Sciences,Jilin Agricultural University,Changchun 130118,China [2]State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China [3]College of Resources and Environment,Qingdao Agricultural University,Qingdao 266109,China [4]Jiangsu Key Laboratory for Eco-Agricultural Biotechnology around Hongze Lake,Huaiyin Normal University,Huaian 223300,China

出　　处：《Pedosphere》2020年第2期159-167,共9页土壤圈（英文版）

基　　金：supported by the National Natural Science Foundation of China(Nos.41571231 and 41201221);the National Key Research and Development Program of China(No.2016YFD0200304);the Scientific Instrument and Equipment Development Project of Chinese Academy Sciences(CAS)(No.YJKYYQ20170058);the Natural Science Foundation of Jiangsu Province,China(No.BK2012496);the Youth Innovation Promotion Association,CAS(No.2017362);the Natural Science Foundation of the Jiangsu Higher Education Institutions of China(No.19KJB180010)。

摘　　要：Humic substances(HS),which are defined as a series of highly acidic,relatively high-molecular-weight,and yellow to black colored substances formed during the decay and transformation of plant and microbial remains,ubiquitously occur in nature.Humic substances represent the largest stable organic carbon pool in terrestrial environments and are the central characteristic of the soil.However,the validity of the HS concept and the justification of their extraction procedure have been recently debated.Here,we argue that the traditional humic paradigm is still relevant.Humic substances are distinctive and complex because the extracted HS formed during the humification are chemically distinct from their precursors and are heterogeneous among soils.By reviewing the concept,formation pathways,and stabilization of HS,we propose that the key question facing soil scientists is whether HS are soil microbial residues or unique synthesized compounds.Without revealing the distinctiveness of HS,it is impossible to address this question,as the structure,composition,and reactivity of HS are still poorly known owing to the heterogeneity and geographical variability of HS and the limits of the currently available analytical techniques.In our view,the distinctiveness of HS is fundamental to the soil,and thus further studies should be focused on revealing the distinctiveness of HS and explaining why HS hold this distinctiveness.

关 键 词：heterogeneity HUMIC acid HUMIFICATION HUMUS microbial biomass soil organic matter 

分 类 号：S153.622[农业科学—土壤学]