Comparison study of Normal-Kriging interpolation method on different nutrient characteristics under the same spatial scale | 普通克里金模型对同尺度下不同土壤肥力指标的空间解析力比较

Chinese. 分析相同空间插值方法对不同肥力指标在空间解析力上的差异和适用性，为测土配方施肥提供技术指导。以浙江温岭市为研究区域，采用正态QQ图的方法，对1 926个样点的有机质、碱解氮、有效磷和速效钾4项指标数据均进行预处理检查，剔除异常值；应用普通克里金插值模型及SPSS、GS+和ArcGIS等软件，通过正态转换、半方差函数模型拟合分析和交叉验证分析等方法，对有机质、碱解氮、有效磷和速效钾4项肥力指标进行的插值结果进行比较，判断普通克里金模型对4项常规肥力指标的空间解析力差异。剔除异常值后，有机质、碱解氮、有效磷和速效钾4项肥力指标的有效样本数分别为1 926，1 923，1 924和1 925个，满足县域范围内空间插值研究的要求。在县域测土配方项目高密度取样条件下，使用普通克里金法进行地统计空间插值，其结果精度可满足要求；在既定尺度下，普通克里金插值模型对4项肥力指标的空间解析力从高到低依次为有机质＞碱解氮＞速效钾＞有效磷；当研究指标的变异系数相近时可选择同样的方法进行地统计空间插值，而在变异过于强烈的情况下对插值方法和模型拟合的选择会有更严格的要求。普通克里金插值模型可用于不同养分指标的空间解析力差异分析，以指导实施测土配方施肥。

English. The study was done to reveal the spatial resolution of Normal-Kriging on different soil nutrient characteristics. Interpolation of organic-matter (OM, n=1 926), alkali-hydrolyzable-nitrogen(AN, n=1 923), available-phosphorus(AP, n=1 924) and readily-available-potassium(AK, n=1 925) were studied Via normal-transfer, Semi-variance-fitting-analysis and Cross-validation. The result precision of Normal-Kriging interpolation method was acceptable under conditions of high-density-sampling in the county-based soil-testing-and-fertilizer-recommendation projects; The predicted results’ precision was OM, greater than AN, AN greater than AK, AK greater than AP under the same spatial scale; The soil nutrient characteristics can be interpolated in the same method only while they had a similar coefficient of variation, otherwise the more stringent requirements would be needed. Through comparative study, we clear the resolution of Normal-Kriging on the 4 soil nutrient characteristics, which also provides a beneficial reference for scientific soil-testing-and-fertilizer.