Particle size distribution is an important soil parameter—therefore precise measurement of this characteristic is essential. The application of the widely used laser diffraction method for soil analysis continues to be a subject of debate. The precision of this method, proven on homogeneous samples, has been implicitly extended to soil analyses, but this has not been sufficiently well confirmed in the literature thus far. The aim of this study is to supplement the information available on the precision of the method in terms of reproducibility of soil measurement and whether the reproducibility of soil measurement is characterized by a normal distribution. To estimate the reproducibility of the laser diffraction method, thirteen various soil samples were characterized, and results were analysed statistically. The coefficient of variation acquired was lowest (3.44%) for silt and highest for sand (23.28%). Five of the thirteen tested samples were characterized by a normal distribution. The fraction content of eight samples was not characterized by normal distribution, but the extent of this phenomenon varied between soils. Although the laser diffraction method is repeatable, the measurement of soil particle size distribution can have limited reproducibility. The main cause seems to be small amounts of sand particles. The error can be amplified by the construction of the dispersion unit. Non-parametric statistical tests should be used by default for soil laser diffraction method analysis.

中文翻译：

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激光衍射法测量各种土壤材料的粒径分布—重现性问题

粒径分布是重要的土壤参数，因此精确测量此特性至关重要。广泛使用的激光衍射法在土壤分析中的应用仍然是一个争论的话题。这种方法的精度已在均质样品上得到证明，已隐含地扩展到土壤分析，但是到目前为止，在文献中还没有充分证实这一点。这项研究的目的是就土壤测量的可重复性以及土壤测量的可重复性是否具有正态分布特征补充有关方法精度的可用信息。为了评估激光衍射法的重现性，对13种不同的土壤样品进行了表征，并对结果进行了统计分析。淤泥获得的变异系数最低（3.44％），而沙子最高（23.28％）。13个测试样本中有5个的特征在于正态分布。八个样品的分数含量没有以正态分布为特征，但是这种现象的程度在土壤之间有所不同。尽管激光衍射法是可重复的，但土壤粒径分布的测量可重复性有限。主要原因似乎是少量的沙粒。误差可以通过分散单元的构造来放大。默认情况下，应使用非参数统计检验进行土壤激光衍射法分析。八个样品的分数含量没有以正态分布为特征，但是这种现象的程度在土壤之间有所不同。尽管激光衍射法是可重复的，但土壤粒径分布的测量可重复性有限。主要原因似乎是少量的沙粒。误差可以通过分散单元的构造来放大。默认情况下，应使用非参数统计检验进行土壤激光衍射法分析。八个样品的分数含量没有以正态分布为特征，但是这种现象的程度在土壤之间有所不同。尽管激光衍射法是可重复的，但土壤粒径分布的测量可重复性有限。主要原因似乎是少量的沙粒。误差可以通过分散单元的构造来放大。默认情况下，应使用非参数统计检验进行土壤激光衍射法分析。误差可以通过分散单元的构造来放大。默认情况下，应使用非参数统计检验进行土壤激光衍射法分析。误差可以通过分散单元的构造来放大。默认情况下，应使用非参数统计检验进行土壤激光衍射法分析。