ISRIC Report 2021/03: How well does Digital Soil Mapping represent soil geography? An investigation from the USA: Case Study

We present four case studies in the continental USA illustrating the application of methods, developed in a companion paper in the journal SOIL Discussions (https://doi.org/10.5194/soil-8-559-2022), to evaluate the spatial patterns of the geographic distribution of soil properties as shown in gridded maps produced by Digital Soil Mapping (DSM) at global(SoilGrids v2), national (Soil Properties and Class 100m Grids of the USA), and regional (POLARIS soil properties) scales, and compare them to spatial patterns known from detailed field survey (gSSURGO). These case studies reveal substantial differences in the performance of DSM due to (1) study area and its soil geomorphology; (2) soil property being predicted; (3)depth slice being predicted. Each case is unique and reveals different aspects of the reference and DSM products. A set of R Markdown scripts is referenced so that readers can apply the analysis for areas of their interest.