禹城市耕地土壤盐分与有机质的指示克里格分析

针对目前黄淮海平原盐渍土改良区存在的土壤盐碱、瘠薄等障碍问题，以该区域典型县域禹城市为研究对象，综合运用GIS和非参数地质统计学的指示克立格法，对0-20 cm深度的耕地土壤盐分和有机质的空间变异性进行了分析，并给出了土壤盐分和有机质满足一定阀值条件的概率分布图。结果表明，土壤盐分和有机质采用指示克里格方法都可以获得较为稳健的变异函数；受结构性因素与随机性因素共同影响，它们的指示半方差均表现为中等强度的空间自相关性，且单元指示克里格与多元指示克里格插值结果表明，土壤盐分、有机质的概率分布存在空间上的规律性与相似性；在空间分布上，研究区域土壤盐分含量高和有机质含量低的高概率区域主要分布在西北部的张庄镇、西部的房寺镇以及南部的莒镇乡等地区，该区域有一定的次生盐渍化风险；而土壤盐分含量高和有机质含量低的低概率分布区域主要分在徒骇河流经的河滩高地，土壤类型为褐土化潮土，是研究区域的主要高产区，基本无盐渍化。研究获取的综合指示概率分布图和概率风险评价对土壤可持续利用管理具有重要意义，为区域土壤质量的提高和土壤障碍因子消减提供参考。

Evaluation on spatial distribution of soil salinity and soil organic matter by indicator Kriging in Yucheng City

Soil salinization and low soil fertility are the key limiting factors for soil improvement in the Huanghuaihai Plain at present. To evaluate the spatial variation of soil salinization and fertility, we used GIS and indicator Kriging of nonparametric geostatistics to analyze the spatial distribution of soil salinity content and organic matter content in top 20cm soils for a typical county located in Huanghuaihai Plain, Yucheng City,northwest of Shandong province. The probability maps for soil salinity content and organic matter content that met the given thresholds(soil salinity threshold is 0.29 dS/m, organic matter threshold is 15 g/kg) were presented.The results indicated that the indicator Kriging method was able to produce stable semivariograms for both soil salinity content(greater than 0.29 dS/m) and organic matter content(less than 15 g/kg),which exhibited moderate spatial autocorrelation due to the combined effects of structural and stochastic factors in our study area. Both univariate indicator Kriging and multiple-variable indicator Kriging(soil salinity greater than 0.29 dS/m and organic matter less than 15 g/kg) interpolation maps showed that the probability distribution of soil salinity and organic matter was regular and similar in spatial variation. Specifically, high soil salinity content and low soil organic matter content occurred at northwest (Zhangzhuang Town), west (Fangsi Town) and south (Juzheng Town) of the study area, in which the soils to some degree suffered from secondary salinization risk. In addition, high soil salinity content and low soil organic matter content occurred at the high flood plain along the Tuhai river, the major high-yield region in the study area where the soil was classified as alluvial Cinnamon soil and suffered from low salinization risk. Since the integrative probability map as well as its risk assessments are significantly valuable to the management and sustainable use of soil resource, our results are of great use to the soil improvement in the study area.