名山河流域不同土壤类型和土地利用方式下有机碳的分布特征

以名山河流域不同类型土壤为研究对象,研究了不同土地利用方式下土壤有机碳和团聚体中有机碳含量的分布特征。结果表明:(1)名山河流域3种类型的土壤有机碳含量在17.50~34.70g/kg之间,含量高低表现为水稻土黄壤紫色土,水稻土含量分别是黄壤和紫色土的1.32,1.39倍;从不同的土地利用方式看,水田土壤有机碳及活性有机碳含量显著高于旱地、茶园和果园,土壤活性有机碳与土壤有机碳呈极显著正相关(R2=0.884 6);(2)土壤有机碳含量在土壤剖面中表现出随着土层深度的增加而降低的趋势,表层土壤(0—20cm)有机碳含量由高到低依次为水稻土黄壤紫色土,下层土壤(20—40cm)有机碳含量为水稻土紫色土黄壤,土壤活性有机碳含量的分布具有相似规律;(3)在不同土地利用方式下,表层土壤(0—20cm)有机碳含量大小关系表现为水田旱地果园茶园,下层土壤(20—40cm)有机碳含量表现为水田果园茶园旱地,水田表层、下层土壤活性有机碳含量均极显著地高于旱地、果园、茶园,再次证明活性有机碳是表征有机碳特性的重要指标;(4)3种类型土壤的团聚体在不同的利用方式下的有机碳含量表现出随着土壤剖面加深而降低的趋势,土壤团聚体的单位有机碳含量随着粒径的减小呈现波浪形的变化趋势,各粒径团聚体中的有机碳含量与土壤有机碳含量呈正相关关系。综上可知,土壤类型的差异和土地利用方式的不同会对土壤有机碳及各粒径团聚体中有机碳的含量及分布特征产生一定的影响。

Distribution of Organic Carbon under Different Soil Types and Utilization Patterns in Mingshan River Watershed

The distribution of soil organic carbon was studied under different soil types and land use patterns,samples were collected in Mingshan River watershed and analysed in the laboratory.The results showed as follows:(1) Organic carbon content of the three types of soil was 17.50-34.70 g/kg,and followed the order of paddy soil ＞ yellow soil ＞ purple soil;From the way of land use,the content of paddy soil organic carbon and active organic carbon were significantly higher than those of the dry land,tea gardens and orchards,soil active organic carbon and soil organic carbon were significantly positively correlated (R2=0.884 6).(2) The content of organic carbon of soil decreased gradually with the increase of soil depth.Soil organic carbon content showed the order of paddy soil ＞ yellow soil ＞ purple soil at the depth of 0-20 cm,and paddy soil ＞ purple soil ＞ yellow soil at the depth of 20-40 cm,and active organic carbon showed a similar pattern.(3) Under different land use patterns,organic carbon content in the surface soil followed the order of paddy field ＞ dry land ＞ tea garden,and that in the subsoils (20-40 cm) was in the order of paddy field ＞ tea garden ＞ dry land.Active organic carbon contents in both in the upper and the lower layers of the paddy field were significantly higher than those of the dry land,orchard and tea garden.It is proved again that active organic carbon is one of the important indicators of organic carbon.(4) Organic carbon content of soil aggregates decreased with the increase of soil depth,at the same time,the organic carbon content of soil aggregates showed a wavy changing trend with the decreasing particle size.Organic carbon content of soil aggregates was positively correlated with total soil organic carbon content.In conclusion,organic carbon contents in the soil and soil aggregates of different particle sizes were influenced by soil types and different utilization pattern,the distribution characteristics of organic carbon in the soil and soil aggregates were different.