黄土沟壑区小流域土壤pH值的空间分布及条件模拟

Spatial distribution and conditional simulation of soil pH values in small watershed of loessial gully region

土壤pH值是影响土壤养分有效性和化学物质在土壤中行为的主要因素,研究土壤pH值的空间分布特征对于土壤养分管理和土壤污染预测具有重要意义。该文用地统计学方法研究了环境因素复杂的黄土高原小流域土壤pH值空间分布特征。结果表明,黄土沟壑区小流域土壤pH值具有球形—指数套合模型的空间结构特征,其空间异质性主要来源于流域内土地利用和土壤侵蚀等随机因素。与有机质协同的Kriging法能较好地对土壤pH值进行估值,其估值范围小于实测数据,估值误差来源于复杂的环境因素。序贯高斯条件模拟的土壤pH值范围与实测数据接近,模拟的平均值低于实测数据,模拟误差来源于模拟过程中独特的Kriging算法及高斯特性。

Soil pH value is the major property influencing the availability of soil nutrients and behaviors of agricultural chemicals. Understanding the spatial distribution of soil pH values has vital significance for nutrient management and soil pollution prediction. Geostatistical method was used to study the distribution of soil pH values in a watershed in the gully region of the Loess Plateau where landforms, landuse patterns and soil types vary greatly. The results showed that soil pH values in the watershed presented the Spherical-Exponential combined variogram models. The spatial heterogeneity was mainly derived from the random factors such as landuse patterns and soil erosion in the watershed. Crossed Kriging on soil pH value, using organic matter as auxiliary variables, was consistently more effective than Kriging on soil pH value alone and could be used to estimate soil pH value distribution in watershed. The error of crossed Kriging was existed in the complicated environmental factors. Simulated values by sequential Gaussian conditional simulation had the same range but lower average soil pH values compared with measured data. The error was derived from the special Kriging method and the Gaussian treat during the simulation.