团聚体大小分布对孔隙结构和土壤有机碳矿化的影响  

Effects of Aggregate Size Distribution on Soil Pore Structure and Soil Organic Carbon Mineralization

作　　者：荣慧 房焕 张中彬[1] 蒋瑀霁[1] 赵旭[1] 单军 彭新华[1,2] 孙波 周虎[1] RONG Hui;FANG Huan;ZHANG Zhongbin;JIANG Yuji;ZHAO Xu;SHAN Jun;PENG Xinhua;SUN Bo;ZHOU Hu(State Key Laboratory of Soil and Sustainable Agriculture,Institute of Soil Science,Chinese Academy of Sciences,Nanjing 210008,China;University of Chinese Academy of Sciences,Beijing 100049,China;College of Agricultural Science and Engineering,Hohai University,Nanjing 210098,China)

机构地区：[1]土壤与农业可持续发展国家重点实验室(中国科学院南京土壤研究所),南京210008 [2]中国科学院大学,北京100049 [3]河海大学农业科学与工程学院,南京210098

出　　处：《土壤学报》2022年第2期476-485,共10页Acta Pedologica Sinica

基　　金：国家自然科学基金委员会-中国科学院大科学装置科学研究联合基金项目(U1832188)资助。

摘　　要：土壤团聚体在外部和内部因素影响下发生团聚和破碎过程,形成不同大小分布的团聚体。团聚体大小分布的变化会改变土壤孔隙结构,影响各种土壤物理、化学和生物学过程,进而影响土壤有机碳(SOC)的周转。选择三种长期施用不同量有机肥的红壤(不施肥,CK;施低量有机肥,LM;施高量有机肥,HM),过不同大小孔径筛(5 mm,S_(5);2 mm,S_(2);0.5 mm,S_(0.5))改变团聚体的大小分布,然后填装土柱(直径2.9 cm、高度4 cm),填装容重为1.3 g·cm^(-3)。利用X射线显微CT(Computed Tomography)成像技术分析土壤的孔隙结构,采用室内培养法测定土壤有机碳矿化量。结果表明,团聚体大小对孔隙结构有极显著的影响。相较于S_(5)和S_(2)处理,S_(0.5)处理土壤的大孔隙度(>16μm)降低了83.0%~93.9%,孔隙连通性降低了95%以上。而S_(5)和S_(2)处理的大孔隙度和孔隙连通性只在HM土壤中有显著差异,在CK和LM土壤中无显著差异。团聚体大小分布对土壤有机碳矿化量有显著影响。团聚体破碎增加了土壤有机碳矿化量。在CK土壤中,S_(0.5)的有机碳累积矿化量较S_(5)和S_(2)分别高64.2%和79.1%;在HM土壤中,S_(0.5)的有机碳累积矿化量较S_(5)和S_(2)分别高19.3%和14.1%。与之不同的是,在LM土壤中,S_(0.5)的有机碳累积矿化量与S_(5)无显著差异,可能是受到孔隙结构的影响。相关分析发现,土壤有机碳累积矿化量与16~30μm孔隙的孔隙度呈显著的正相关关系。团聚体大小分布的变化改变了土壤的孔隙结构,大团聚体破碎降低了填装土柱的大孔隙度。团聚体破碎促进土壤有机碳的矿化,一部分原因是释放出了被保护的有机碳。此外,团聚体大小改变导致的孔隙结构变化可能是影响土壤有机碳矿化的另一个重要因素。【Objective】Soil aggregate size distribution evolves due to soil aggregation and breakdown processes that occur under natural and anthropogenic impact.A change in aggregate size distribution can alter soil pore structure,which might also influence soil water transportation,gas exchange and microbial activities.Thus,this may potentially affect soil organic carbon(SOC)mineralization.Therefore,this study aimed to investigate the effect of aggregate size distribution on soil pore structure and the SOC mineralization.【Method】Soil samples were collected from a long-term field experimental site with treatments receiving different amount of pig manure(No manure,CK;Low manure,LM;High manure,HM).The soil samples were passed through sieves with 5.0(S_(5)),2.0(S_(2)),or 0.5 mm(S_(0.5))openings to create different aggregate size distributions,with the maximum aggregate sizes corresponding to 5.0,2.0 and 0.5 mm,respectively.The sieved aggregates were repacked into soil columns(diameter 2.9 cm,height 4 cm)with a bulk density of 1.3 g·cm^(-3).Soil columns were incubated for 57 days and SOC mineralization was measured during this period.Also,the soil pore structure was quantified using X-ray micro-computed tomography(μ-CT)imaging.【Result】Sieving altered soil aggregate size distribution,which resulted in significantly different soil pore structure in the repacked columns.Compared to S_(5)and S_(2)treatments,the S_(0.5)treatment significantly decreased the image-based porosity(>16μm)by 83.0%-93.9%and pore connectivity by more than 95%.The differences in macroporosity and pore connectivity between S_(5)and S_(2)treatment were significant for the HM soil,but not for the CK and LM soil.Also,aggregate size distribution had a significant effect on SOC mineralization.The breakdown of aggregates increased SOC mineralization.The cumulative SOC mineralization amount of S_(0.5)treatment was 64.2%-79.1%and 14.1%-19.3%higher than that of S_(5)and S_(2)treatments for the CK and HM soils,respectively.However,there was no significan

关 键 词：红壤 土壤团聚体 孔隙结构 土壤有机碳矿化 X射线显微CT 

分 类 号：S152.4[农业科学—土壤学]