不同种植年限红壤柑橘园土壤腐殖质化学组成和结构特征差异  

Differences in Chemical Composition and Structural Characteristics of Soil Humus along Different Cultivation Chronosequence of Citrus Orchards

作　　者：张雅雯 刘灿 郭新春 郑太辉 ZHANG Yawen;LIU Can;GUO Xinchun;ZHENG Taihui(College of Land Resources and Environment/Key Laboratory of Agricultural Resources and Ecology inPoyang Lake Watershed of Ministry of Agriculture and Rural Affairs in China,Jiangxi Agricultural University,Nanchang 330045,China)

机构地区：[1]江西农业大学国土资源与环境学院/农业农村部鄱阳湖流域农业资源与生态重点实验室,江西南昌330045

出　　处：《江西农业大学学报》2023年第6期1575-1587,共13页Acta Agriculturae Universitatis Jiangxiensis

基　　金：国家自然科学基金项目(42167047);江西省自然科学基金项目(20202BABL203029)

摘　　要：【目的】长时间序列尺度上监测果园土壤有机碳化学组成和分子结构,深入了解果园土壤固碳增汇功能对人类种植活动的响应规律,可以为农业固碳减排提供理论依据,助力双碳目标实现。【方法】以长期种植的红壤柑橘园为研究区,采集不同种植年限(10年、30年、50年)土壤(0~20 cm)样品,分离纯化得到胡敏酸(HA)馏分(F1~F10)、低碳胡敏素(HuL)和高碳胡敏素(HuH)等腐殖质组分,利用元素分析、红外光谱、核磁共振3种手段,综合分析HA、HuL、HuH化学组成及结构变化。【结果】(1)化学组成:胡敏酸馏分与胡敏素元素组成以C、O为主,随种植年限延长C含量增大(除F9~F10),种植年限为50年的F1~F2、F3~F8、HuL、HuH C含量较种植年限为10年的增大36.1%、38.34%、61.69%、72.25%;HA的F1~F2、F3~F8馏分随种植年限的延长C/N分别下降40.84%、44.33%,HuH、HuL增大62.33%、42.55%,种植年限越长越有利于HA含氮基团的形成而不利于胡敏素含氮基团的形成;F1~F2、F3~F8、F9~F10脂化度分别增加12.8%、5.7%、6.6%,芳化度随之降低相应比例;HuH、HuL脂化度降低7.2%、0.9%,芳化度增大相应比例;芳香碳含量随种植年限延长HA馏分,分别下降10.9%、5.38%、3.83%、而HuL、HuH分别增加2.59%、5.68%。(2)结构特征:不同种植年限腐殖质组分红外光谱峰型、峰位相似,但吸收强度有差异,HuH的结构与HA结构相似,但HuL的结构更为简单,并且C骨架未发生变化;HA的H/C,F1~F2、F3~F8馏分随种植年限的延长下降30.03%、16.16%,随种植年限的延长HA的化学结构逐渐以芳香结构为主且不饱和程度和芳香性越高。【结论】柑橘果园土壤不同腐殖质组分化学组成、相对应的结构单元、官能团数量及各有机碳比例会因种植年限而改变,土壤有机碳含量逐年增加,柑橘的连年种植有利于土壤腐殖质结构稳定,进而增强土壤碳汇能力。[Objective]Long-term monitoring the chemical composition and molecular structure of soil organic carbon in orchards is helpful in understanding the responses of orchard soil carbon sequestration and sink enhancement function to human cultivation activities,thus providing theoretical basis for agricultural carbon sequestration and emission reduction,and achievement of the double carbon goal.[Method]The long�term planted red soil citrus orchard was taken as the research area.The surface soils(0-20 cm)of citrus orchards with different cultivation chronosequence(10,30,and 50 years)were collected.Humic acid(HA)fractions(F1-F10),and HuL and HuH fractions from humus were isolated and purified.Besides,elemental analysis,FTIR and CP/TOSS 13C-NMR were used to analyze comprehensively the content and structure changes of HA,HuL and HuH under different cultivation chronosequence.[Result](1)Chemical composition:HA fraction and humin element composition is dominated by C and O.With the extension of planting age,the C content increased(except F9-F10),The C content of F1-F2,F3-F8,HuL and HuH in soils with 50 planting years increased by 36.1%,38.34%,61.69%and 72.25%,compared with soils with 10 planting years;With the extension of planting age,F1-F2 and F3-F8 fractions of HA decreased by 40.84%and 44.33%,respectively,while HuH and HuL increased by 62.33%and 42.55%.The longer the planting period,the more favorable it was for the formation of nitrogen-containing groups of HA and less favorable for the formation of nitrogen�containing groups of humin.The aliphaticity of F1-F2,F3-F8,and F9-F10 increased by 12.8%,5.7%,and 6.6%respectively,and the aromaticity decreased by the corresponding proportions.The aliphaticity of HuH and HuL decreased by 7.2%and 0.9%,and the aromaticity increased correspondingly.With the extension of planting years,the aromatic carbon content of HA fractions decreased by 10.9%,5.38%and 3.83%,respectively,while that of HuL and HuH increased by 2.59%and 5.68%.(2)Structural characteristics:the infrared spectral

关 键 词：种植年限 腐殖质组分 元素分析 红外光谱 固态13C核磁共振 

分 类 号：S153.6[农业科学—土壤学]