| 摘要: |
| 【目的】分析添加秸秆对长期不同碳氮管理土壤团聚体尺度激发效应的影响，为揭示秸秆还田对土壤有机碳（SOC）固持能力的内在影响机理提供理论依据。【方法】以2002年开始的长期定位试验中碳氮管理水平不同的2种供试土壤（S0N0.秸秆不还田+不施氮肥；S1N1.高量秸秆还田+高量氮肥(240 kg/hm2)）为材料，采用室内恒温培养试验，利用干筛法得到3种粒级的团聚体（粗大团聚体、细大团聚体和微团聚体），分别在添加玉米秸秆和不添加玉米秸秆的条件下于25 ℃黑暗培养70 d，测定各粒级团聚体的CO2释放量、表观激发效应(PE)及有机碳（SOC）、可溶性有机碳（DOC）和微生物量碳（MBC）含量。【结果】未添加秸秆时，S0N0和S1N1土壤微团聚体的CO2累积释放量均高于大团聚体（粗大团聚体和细大团聚体）；添加等量秸秆后，2种土壤各粒级团聚体的CO2累积释放量均有提高；在S0N0土壤中，粗大团聚体与微团聚体产生的表观PE无显著差异，但均显著小于细大团聚体；而在S1N1土壤中，不同粒级团聚体表观PE由大到小依次为细大团聚体>粗大团聚体>微团聚体。与未添加秸秆相比，添加秸秆后2种土壤各粒级团聚体SOC含量均显著增加，且2种土壤中各粒级团聚体SOC含量表现为微团聚体>大团聚体。无论添加秸秆与否，在S1N1土壤中，大团聚体的DOC含量均显著高于微团聚体；而在S0N0土壤中，3个粒级团聚体的DOC含量无显著差异。在S1N1土壤中，未添加秸秆时，各粒级团聚体的MBC含量无显著差异；添加秸秆后，微团聚体的MBC含量显著高于大团聚体。在S0N0土壤中，未添加秸秆时，大团聚体的MBC含量显著小于微团聚体；而添加秸秆后，粗大团聚体的MBC含量显著小于微团聚体和细大团聚体。【结论】作物秸秆的投入会因产生激发效应,进而改变土壤各粒级团聚体中原SOC的矿化情况；不管土壤碳氮水平高低，微团聚体对SOC的保护作用均比大团聚体更好。 |
| 关键词: 土壤团聚体 表观激发效应 土壤有机碳 秸秆还田 |
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| 基金项目:国家重点研发计划项目（2016YFD0200308）；陕西省重点研发计划项目（2019ZDLNY01-05-01）；“十二五”国家科技支撑计划项目（2012BAD14B11） |
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| Priming effect of straw addition on different particle-size fractions of soil aggregates under long-term carbon and nitrogen managements |
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CAO Binbin,LI Yunuo,ZHU Yihui,et al
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| Abstract: |
| 【Objective】To provide basis for understanding effect mechanisms of straw return on soil organic carbon(SOC) sequestration,the priming effect (PE) of straw addition on soil aggregates under long-term and different carbon and nitrogen managements were analyzed.【Method】This study used incubation experiment with soils from two long-term experiment testing sites under continuous managements with different crop residues and nitrogen (S0N0 soil:no straw return+unfertilization;S1N1 soil:high straw return+high nitrogen fertilizer:240 kg/hm2).Two soil samples were separated into three aggregate size classes (large macro-aggregates,small macro-aggregates and micro-aggregates) and were incubated with or without maize straw for 70 days under 25 ℃.CO2 emission,apparent priming effect (PE),SOC,dissolved organic carbon (DOC) and microbial biomass carbon (MBC) of each aggregate size class were measured.【Result】Cumulative CO2 emission in micro-aggregates in S0N0 and S1N1 soil without straw addition was higher than in macro-aggregates (both large and small macro-aggregates).The same amount of straw addition can increase cumulative CO2 emissions of all size classes in both soils.There was no significant difference in apparent PE between large macro-aggregate and micro-aggregate in S0N0 soil after straw addition,but both were significantly smaller than those in small macro-aggregate.In S1N1 soil,the apparent PE between aggregate size classes were in the decrease order of small macro-aggregates>large macro-aggre gates>micro-aggregates.Meanwhile,straw addition significantly increased contents of SOC between size classes in both soils.Content of SOC was higher in the micro-aggregates than macro-aggregates,which was opposite to apparent PE.DOC in macro-aggregates was significantly higher than in micro-aggregates in S1N1 soil regardless straw addition.However,there was no significant difference in DOC among size classes in S0N0 soil.In S1N1 soil,MBC in micro aggregates was significantly higher than in macro-aggregates after straw addition,but there was no significant difference among sizes without straw addition.MBC content in macro-aggregates was lower than micro-aggregates without straw addition,but MBC in large macro aggregates was significantly smaller than in micro-aggregates and small macro-aggregates after straw addition in S0N0 soil.【Conclusion】The PE induced by crop straw addition affected mineralization of soil organic carbon in aggregate size classes.Micro-aggregates protected SOC against decomposition better than macro-aggregates regardless soil fertility. |
| Key words: soil aggregate apparent priming effect soil organic carbon straw return |
