苏南山丘区小流域土壤养分特性空间分布

采用地统计学与GIS相结合的方法，以苏南山丘区邓下小流域为研究区，研究了表层土壤(0~20 cm)的pH值、全氮、全磷和速效钾等4种养分的空间变异特征。结果表明：(1)土壤养分的变异系数大小是全磷＞速效钾>全氮＞pH值，存在中等程度的空间变异性。土壤pH的半方差函数理论模型为线性模型，全氮、全磷和速效钾均为指数模型。土壤全氮、全磷和速效钾具有强烈的空间相关性，结构性因素是影响其空间变异的主要因素。土壤pH值存在中等的空间相关性，随机因子引起的空间变异性所占比重较大。(2)土壤pH值自北部向东南部总体趋势递减，中部波动较大。全氮条带状分布明显，自北部向东南部递减。全磷含量具有南北部低，中部较高的趋势，中部波动较大，高值中心出现在这一区域。速效钾在研究区波动较大，高值区域主要集中在中北部，低值区域主要分布在中南部。研究结果可为小流域综合治理中土壤养分管理与植被恢复提供理论依据.

SPATIAL VARIABILITY OF SOIL NUTRIENTS AT A CATCHMENT OF HILLY AREA IN SOUTHERN JIANGSU PROVINCE

Using geostatistical and GIS methods,a case study on Dengxia catchment of hilly area in southern Jiangsu Province was conducted to examine the spatial variability characteristics of soil nutrients in the topsoil(0~20 cm).The indicators of soil nutrients included the pH,total nitrogen(TN),total phosphorus(TP)and available potassium(AK).The results showed:（1）The spatial variability of soil nutrients at the studied area was significant difference,and the variance coefficients followed the order of as total phosphorus>available potassium>total nitrogen>pH.The theoretical semi variogram model of pH was linear model,but TN,TP and AK of which all were exponential model.(2)The spatial distribution of pH and AK also was higher in the north part than that in the southeast,but there were several high value centers existing in the middle and south part just as small block,and they fluctuated acutely.The distribution of TN presented obviously belt shape and was higher in the north than in the southeast,with several lowest value centers embedding in the middle and south part of the area.But the distribution of TP was higher in the middle part than that in the north and southeast part,with several high centers embedding in the middle part.These results provide theoretical foundation for soil nutrients management and vegetation restoration in the studied area.