退耕典型草地土壤饱和导水率及其影响因素研究

Study on Soil Saturated Hydraulic Conductivity and Its Influencing Factors in Typical Grassland of Farmland Conversion

土壤饱和导水率Ks(soil saturated hydraulic conductivity)反映土壤水分入渗能力,是重要的水力参数。通过对云雾山典型草原区不同年限退耕地0~40cm土层的土壤饱和导水率进行测定,并对土壤饱和导水率及其影响因子进行了方差和通径分析。研究表明:退耕过程有利于提高土壤饱和导水率,退耕第3-22年,饱和导水率从4.16mm·min^(-1)增加到6.74mm·min^(-1),提高了61.9%。在这一阶段0~40cm土层土壤团聚体稳定性整体得到改善,其中20~40cm土层土壤团聚体稳定性改善更为明显。退耕开始阶段(3年)土壤有机质含量下降至最低,仅为17.79g·kg^(-1),随后有机质迅速积累,到退耕24年时含量达52.49g·kg^(-1),增加了195.1%。土壤水稳性大团聚体含量和有机质含量是影响饱和导水率的主要因素,水稳性团聚体直接作用更显著,有机质间接作用更显著。每增加1个单位水稳性大团聚体含量,饱和导水率提高2.4%,而土壤有机质含量增加1个单位,土壤饱和导水率只提高1.2%。

Soil saturated hydraulic conductivity is an important parameter to reflect the infiltration capacity of soil water.In this study,the soil saturated hydraulic conductivity（0~40cm）and its influencing factors in typical grassland of farmland conversion in the Yunwu Mountain were investigated by field investigation and laboratory test.The variation of soil saturated hydraulic conductivity was revealed through variance analysis and path analysis.Research showed that the soil saturated hydraulic conductivity significantly increased from 4.16mm·min^（-1） to 6.74mm·min^（-1） in the period of first 3to 22 year,61.9%increase.In this stage,the stability of soil aggregates in 0~40cm soil layer was improved significantly,especially in20~40cm soil layer.In the first three years,content of soil organic matter showed a downward trend,and reached the minimum of 17.79g·kg^（-1） at the third year.Then,the content began to increase,and reached 52.49g·kg^（-1） at the twenty-fourth year,195.1% increase.The content of organic matter decreased with the increase of soil depth.Contents of soil water-stable aggregates and organic matter were main impact factors to the water saturated hydraulic conductivity.When the contents of water-stable aggregates and organic matter increased one unit,the soil saturated hydraulic conductivity increased 2.4%and 1.2%,respectively.