Australian pedogenons in the global context

Soil is inherently a complex and dynamic system. Evaluating its capacity and condition within the soil security assessment framework requires approaches that can account for soil change over time. The pedogenon concept provides such a framework by classifying soils according to homogeneity in soil-forming factors at a defined reference time. This study compares two existing pedogenon maps that are available for Australia: a national pedogenon map (NPM) and a recently developed global pedogenon map clipped to the Australian extent (CGPM). Comparative analysis was undertaken to evaluate pedogenon classes composition and variability. Reclassification between the two maps were performed using: (i) weighted closest centroid method, and (ii) dominant centroid method, enabling the projection of Australian pedogenon classes into a global context. The number of pedogenon classes were comparable (N_NPM = 1370; N_CGPM = 1406). The NPM exhibited greater between-cluster variance than the CGPM, while within-cluster variance was similar between maps. Reclassification using the dominant centroid method was more interpretable and suitable for broad-scale applications. Similar pedogenon classes identified in Australia were also observed globally, supporting the development of harmonised and scalable soil assessments across national and international contexts. • National and clipped global pedogenon maps show comparable class distributions in Australia. • National pedogenon map has higher between-cluster variance than the clipped global pedogenon map. • Dominant-centroid reclassification method is more interpretable than the weighted closest centroid method. • Australian pedogenon classes can be projected into the global context.