Quantitative evidence for the fundamental spectral shape similarity existing between different soils is presented utilizing Pearson's correlation and SAM (Spectral Angle Mapper) analysis in-between signatures representing thousands of soil samples collected from different environments around the world. A universal quadratic soil line (UQSL) was found to highly fit these representative signatures as well as spectra from the ISRIC (International Soil Reference and Information Center) global database including soil samples collected from 58 countries. K-means clustering of ISRIC spectral reflectance deviations from the UQSL facilitated identification of 5 characteristic deviation patterns. Significant correlation was found for a set of 1000 soil samples between changes in multiple chemical properties and corresponding reflectance changes between these clusters. Future availability of large global soil data bases may allow improved determination of the UQSL and generalization of its deviation patterns relationships with PBC (Physical, Biological and Chemical) properties for wide areas monitoring of soil conditions.

利用 Pearson 的相关性和 SAM（光谱角映射器）分析，代表从世界各地不同环境收集的数千个土壤样本之间的特征，提供了不同土壤之间存在的基本光谱形状相似性的定量证据。发现一条通用二次土壤线 (UQSL) 与这些代表性特征以及来自 ISRIC（国际土壤参考和信息中心）全球数据库的光谱高度吻合，该数据库包括从 58 个国家收集的土壤样本。与 UQSL 的 ISRIC 光谱反射偏差的 K 均值聚类有助于识别 5 个特征偏差模式。在一组 1000 个土壤样品中，发现多个化学性质的变化与这些簇之间相应的反射率变化之间存在显着相关性。大型全球土壤数据库的未来可用性可能允许改进 UQSL 的确定并推广其偏差模式与 PBC（物理、生物和化学）特性的关系，以广泛监测土壤状况。