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基于全国第二次土壤普查的1 491个水稻土剖面数据,研究了行政区幅度(行政大区、省级、地区级)和土壤区幅度(土壤区、土壤带、土区)下水稻土氮密度的变异情况及其对幅度拓展的响应。结果表明,中国水稻土0~20 cm和0~100 cm土壤平均氮密度为18.7 t.hm-2和12.4 t.hm-2,土壤氮素的空间变异性总体随幅度拓展而增大。在不同土壤区幅度下,0~20 cm全氮密度组内和组间变异性随研究区幅度的减小而减小;从土壤区到土区尺度,0~100 cm全氮密度组间变异率从250%左右下降至不足50%,而在行政大区和省级尺度时全氮密度的组间变异性没有太大变化,变异率都小于100%,到地级市尺度时,组间变异率又达到了400%,说明同一地区所选择的研究幅度尺度不一样氮密度变异率差异也很大。因此,在今后的水稻土调查采样设计时,根据不同幅度尺度的变异率大小来选择合适的布点方式和样点数是十分必要的。
Based on the data of 1 491 paddy soil profiles from the Second National Soil Survey, the effects of administrative area (administrative area, provincial and district level) and soil bulk density (soil area, soil zone and soil area) on soil nitrogen density Variation and its response to amplitude expansion. The results showed that the average nitrogen densities of paddy soil at 0-20 cm and 0-100 cm in China were 18.7 t.hm-2 and 12.4 t.hm-2, respectively. The spatial variability of soil nitrogen generally increased with the increase of soil depth. In different soil regions, the variability within and between 0 ~ 20 cm total nitrogen density group decreased with the decrease of the amplitude of the study area. From the soil area to the soil area scale, the variation of 0 ~ 100 cm total nitrogen density Rate dropped from about 250% to less than 50%, while in the administrative area and the provincial scale when the total nitrogen density variability between the groups did not change much, the mutation rate of less than 100% to the prefecture-level city scale, The rate of variation reached 400% again, which indicates that the study area of the same area is not the same. Therefore, in the future sampling design of paddy soil survey, it is necessary to choose the appropriate distribution method and sampling points according to the variation rate of different amplitude scales.