不同植茶年限土壤团聚体有机碳的分布特征

【目的】探索和了解茶园土壤有机碳的稳定性及碳固持能力。【方法】采用野外调查和室内分析相结合的方法，开展植茶年限为15 a、22 a、30 a和50 a土壤团聚体有机碳分布特征研究。【结果】随着土壤团聚体粒径的减小，团聚体总有机碳、活性有机碳、颗粒有机碳、水溶性有机碳和可矿化碳含量增加，最大值主要集中于＜0.25 mm、0.5—0.25 mm团聚体中，而团聚体微生物量碳含量则随粒径减小而先增加再减小，最大值分布于5—2 mm团聚体中，团聚体中各组分有机碳占总有机碳比例随团聚体粒径减小而减小；随植茶年限的延长，团聚体中总有机碳含量增加，活性有机碳和颗粒有机碳先降低再增加，植茶22 a时含量最低，而水溶性有机碳、可矿化碳和微生物量碳则呈现先增加再降低的趋势，植茶30 a时含量最高，且团聚体中各组分有机碳占总有机碳比例均随着植茶年限的延长呈现下降的趋势；土壤团聚体总有机碳以及各个碳组分含量均为0—20 cm土层大于20—40 cm土层，而土壤团聚体各组分有机碳占总有机碳的比例均为20—40 cm土层大于0—20 cm土层。【结论】较小粒径团聚体有机碳稳定性较强，土壤有机碳固持能力存在临界植茶年限；0—20 cm土层碳汇效应较20—40 cm土层强。

Distribution Characteristics of Organic Carbon Fractions in Soil Aggregates Under Tea Plantation of Different Ages

【Objective】The purpose of this study was to explore and learn about the soil organic carbon stability and carbon sequestration capacity.【Method】 Based on the method of field investigation and laboratory analysis, the distribution of organic carbon fractions in soil aggregates was studied under tea plantation of different ages.【Result】The content of total organic carbon (TOC), labile organic carbon (LOC), particulate organic carbon (POC), water soluble organic carbon (WSOC) and potential mineralized carbon (PMC) in soil aggregates comparatively increased as soil aggregates particles diameter reduced, the maximum value concentrated was found at ＜0.25 mm or 0.5-0.25 mm diameter. But the content of soil aggregates microbial biomass carbon(MBC) comparatively decreased when soil aggregates particles diameter reduced, the maximum value was found at 5-2 mm diameter. The proportion of organic carbon fractions to total organic carbon in soil aggregates decreased as soil aggregates particles diameter reduced. The content of TOC in soil aggregates increased when the age of tea plantation addition, the content of LOC and POC in soil aggregates first decreased and then increased as the age of tea plantation addition, the maximum value was found at tea plantation of 22 age. The content of WSOC, PMC and MBC in soil aggregates first increased and then decreased as the age of tea plantation increased, the maximum value was found at tea plantation of 30 age. The proportion of organic carbon fractions to total organic carbon in soil aggregates decreased as the increase of tea plantation age. The contents of TOC and organic carbon fractions in soil aggregates in 0-20 cm layer were greater than in 20-40 cm layer and the proportion of organic carbon fractions to total organic carbon in soil aggregates in 20-40 cm layer was greater than in 0-20 cm layer. 【Conclusion】 The stability of organic carbon was strong for the smaller particle size aggregates, and there was the critical age of plant tea for the soil organic carbon sequestration abilities. The carbon sink effect in 0-20 cm soil layer was stronger than that in 20-40 cm soil layer.