福鼎茶园土壤团聚体有机碳分布与分子结构特征

Organic Carbon Distribution and Molecular Structure Characteristics of Soil Aggregates in Fuding Tea Garden

以福建省福鼎市白琳镇(BL)、点头镇(DT)、磻溪镇(PX)、管阳镇(GY)和太姥山镇(TMS)的茶园土壤为研究对象,研究其团聚体组成及稳定性,各粒级团聚体有机碳含量、固碳贡献率及有机碳红外光谱,旨在从团聚体尺度揭示茶园土壤有机碳分布及其分子结构特征。结果表明:(1)不同采样地土壤团聚体组成存在差别,但随土层加深,大团聚体(0.25~2 mm)和微团聚体(0.053~0.25 mm)含量均减少,而粉—黏粒团聚体(<0.053 mm)含量增大;(2)随土层加深,所有采样地平均重量直径(MWD)和几何平均直径(GMD)减小,分形维数(D)增大,团聚体结构稳定性降低;(3)各粒级团聚体有机碳含量随土层加深而减小,固碳贡献率主要受团聚体含量的影响,大团聚体固碳贡献率相对更大;(4)各粒级团聚体有机碳均主要来源于多糖碳或脂肪碳,0—15 cm土层土壤粉—黏粒团聚体比大团聚体和微团聚体有机碳更稳定,15—30 cm土层各级团聚体均比0—15 cm土层对应粒级团聚体有机碳更稳定。研究成果可为茶园土壤有机碳的科学管理提供理论参考。

The soil of tea garden in Bailin Town(BL),Diantou Town(DT),Panxi Town(PX),Guanyang Town(GY)and Taimushan Town(TMS)in Fuding City,Fujian Province were taken as the research object.The composition and stability of aggregates,organic carbon content,carbon sequestration contribution rate and infrared spectrum of organic carbon of each particle size aggregates were studied to reveal the distribution and molecular structure characteristics of soil organic carbon in tea garden soil from the aggregate scale.The results showed that:(1)The composition of soil aggregates differed among sampling sites,but with the deepening of soil layer,the content of macroaggregates(0.25~2 mm)and microaggregates(0.053~0.25 mm)decreased,while the content of silt-clay aggregates(<0.053 mm)increased in all sampling sites.(2)Decreased in mean weight diameter(MWD)and geometric mean diameter(GMD)and increased in fractal dimension(D)of all sampled sites with deepening of the soil layer and decreased in structural stability of the agglomerates.(3)The organic carbon content of the aggregates decreased with the deepening of the soil layer,and the contribution rate of carbon sequestration of aggregates was mainly controlled by the percentage of aggregates,and the contribution rate of carbon sequestration of macroaggregates was relatively larger.(4)The organic carbon of each size aggregates was mainly derived from polysaccharide carbon or aliphatic carbon.The silt-clay aggregates in 0—15 cm soil layer had more stable carbon than those in macroaggregates and microaggregates.The aggregates in the 15—30 cm soil layer had more stable carbon than the corresponding size aggregates in the 0—15 cm soil layer.The research results can provide theoretical reference for the scientific management of tea garden soil organic carbon.