为分析南水北调(中线)丹江口库区不同土地利用方式下土壤团聚体稳定性及其导水率,揭示人为活动对土壤结构和水力特性的作用与影响,以库区内3种不同土地利用方式(旱地、水田、林地)土壤为研究对象,经干筛测定团聚体的组成状况,探究了不同土地利用方式下土壤团聚体、土壤有机碳和土壤饱和导水率的相互关系。结果 表明:不同土地利用方式下土壤团聚体机械稳定性表现为旱地最高,林地次之,水田最低; 有机碳含量则表现为林地>水田>旱地。不同土地利用方式下各粒径团聚体中的有机碳含量分布也各不相同,旱地土壤有机碳在粒径<0.25 mm的团聚体中含量最高,水田土壤有机碳分布较为均匀,林地土壤有机碳主要集中在粒径<1 mm的团聚体中。饱和导水率表现为林地>旱地>水田。相关性分析表明饱和导水率与有机碳含量呈显著正相关关系,但与团聚体机械稳定性没有明显关系。同时土壤MWD值和GMD值与有机碳含量都呈现出显著的负相关关系,表明土壤有机碳在土壤团聚体机械稳定性和土壤导水率方面都起着重要的作用。
In order to analyze the aggregate stabilities and water conductivities of soils under different land use patterns in the Danjiangkou reservoir area of the South-to-North Water Diversion Project(middle route), and to reveal the effects of human activities on soil structure and hydraulic characteristics, three land use patterns including dry land, paddy fields and woodland in this area were studied. The composition of soil aggregates was determined by dry sieving to explore the relationships between soil aggregates, soil organic carbon and soil saturated water conductivity under different land use patterns. The results show that the mechanical stability of soil aggregates is the highest in dry land, followed by forest land, and the lowest in paddy field; the organic carbon content is the highest in the woodland, followed by the paddy field and the least in the dry land; the distributions of organic carbon in different particle size aggregates under different land use patterns are also different; the organic carbon content in aggregate with particle size <0.25 mm in dryland is the highest, and the distribution of soil organic carbon in paddy fields is relatively uniform; the organic carbon content mainly concentrates in agglomerates with a particle size of <1 mm in forestland; the saturated hydraulic conductivity decreases in the order: forest land>dry land>paddy field. Correlation analysis shows that there is significant positive correlation between saturated hydraulic conductivity and organic carbon content, but is not correlation between saturated hydraulic conductivities and the mechanical stabilities of aggregates. At the same time, soil MWD value and GMD value have the significant negative correlation with organic carbon content, indicating that soil organic carbon plays an important role in mechanical stability of aggregate and hydraulic conductivity of soil.
