【摘要】 土壤机械组成是土壤重要的性质之一,其空间变异研究主要在大尺度开展,小尺度的研究也具有重要意义,却较少受到关注。本研究采用吸管法测定河北坝上地区坡面尺度32个采样点6个深度的土壤机械组成,利用地统计与GIS相结合方法分析土壤机械组成的三维空间变异,探究坡面尺度土壤机械组成空间变异的主要影响因素。结果表明:坡面尺度土壤各粒级含量具有较强的空间自相关性。凸坡、坡上和坡中的砂粒含量较高,粉粒、黏粒则与之相反。随着深度的增加,土壤砂粒含量波动增加,粉粒含量波动下降,黏粒含量则比较稳定,且土壤机械组成空间变异性有增强趋势。研究坡共存在黏壤土等5种土壤质地类型。坡型和坡位是影响土壤机械组成空间分布的主要因素,该尺度存在与大尺度相当数量的土壤质地类型,表明小尺度土壤机械组成与土壤质地的空间变异信息不容忽视。更多还原

【Abstract】 [Background] Particle size distribution( PSD) is one of the most important properties of soil,and its spatial variability is important for soil erosion modeling and soil and water conservation planning. Previous studies mainly focused on the spatial variability of PSD at large scales and paid little attention to it at small scales. However,the spatial variability of PSD at small scales is an important and undissolved problem as it can effectively refine soil and water conservation practices. Bashang area is a typical agro-pastoral transition zone with serious soil erosion problem,and the spatial variability of PSD of this area is rarely reported and urgently need to be investigated. [Methods] In this study,PSD at 6 depths( 0-5 cm,5-10 cm,15-20 cm,25-30 cm,40-45 cm and 55-60 cm) from 32 sampling points which were located at different slope types and positions in a slope of Bashang area,Hebei province was determined by pipette method. Spatial variation of PSD was analyzed using geostatistics and spatial interpolation for each depth,and the vertical variation of PSD was also analyzed. Soil texture was determined based on the PSD,and its spatial variability was also investigated. The main influencing factors of the spatial variability of PSD and soil texture at slope scale were discussed. [Results] The results show that the spherical model and Gaussian model could be used to describe the semi-variograms of sand,silt and clay particles at all depths. Most of sand,silt and clay particles at most depths have a strong spatial autocorrelation at this slope scale. The sand particles in convex slope,upper slope and central slope are high,while the silt and clay particles are the opposite. With the increase of soil depth,the sand particles tend to increase,the silt particles tend to decrease,and the clay particles are relatively stable. Furthermore,the spatial variation intensity tends to increase with depth as well. There are totally five soil texture types in the slope including clay loam,silt clay loam,loam,sand clay loam and sandy loam,and the main soil texture is clay loam. The spatial variability of soil texture is strong at convex slope and deep layer. Topographic factors including slope position and slope type affect the intensity of soil erosion and lead to the redistribution of soil particles in the slope. Sand particles are less easily to be eroded,thus they are higher in the convex slope,upper slope and central slope. [Conclusions] Slope position and slope type are the main factors that influence the spatial distribution of PSD at slope scale.The number of soil texture types at slope scale is almost equal to that of large scale,and this verifies the importance of the study on spatial variation of soil texture at small scale. Such studies can provide important information for more reliable soil mapping and more precise land management.更多还原