"Black soils" in the Russian Soil Classification system, the US Soil Taxonomy and the WRB: quantitative correlation and implications for pedodiversity assessment

Authors: SOROKIN, ALEXEY - Lomonosov University; Owens, Phillip; LANG, VINCE - Szent Istvan University; ZHOU-DONG, JIANG - Shenyang Agricultural University; MICHELI, ERIKA - Szent Istvan University; KRASILNIKOV, PAAVEL - Lomonosov University

Submitted to: Catena
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/7/2020
Publication Date: 8/7/2020
Citation: Sorokin, A., Owens, P.R., Lang, V., Zhou-Dong, J., Micheli, E., Krasilnikov, P.V. 2020. "Black soils" in the Russian Soil Classification system, the US Soil Taxonomy and the WRB: quantitative correlation and implications for pedodiversity assessment. Catena. 196:104824. https://doi.org/10.1016/j.catena.2020.104824.
DOI: https://doi.org/10.1016/j.catena.2020.104824

Interpretive Summary: In most human cultures, black color of topsoil is considered to be evidence of high soil fertility and thus used for naming soils. We compared selected soil groups with organic matter–enriched horizons of the Russian Soil Classification System, the United States Soil Taxonomy and the World Reference Base for Soil Resources. It is important for the international community to discuss these black soils and the criteria these naming systems are using to group these soils. We found that the groups of the Mollisol Order in the US Soil Taxonomy had small taxonomic distances between each other, except the soils with shallow depth to the rock, duripan or permafrost. However, both the WRB groups and Russian soil types had large taxonomic distances realated to US Soil Taxonomy groups. We ascribed the difference to the geographical bias of the databases. Work is continuing to link these soil groupings to allow communication within the global scientific community.

Technical Abstract: This study addressed the recently proposed concept of “black soils” from the point of view of their correspondence to the taxa of existing soil classifications. We compared selected soil groups with organic matter–enriched horizons of the Russian Soil Classification System, the United States Soil Taxonomy and the World Reference Base for Soil Resources. The research evaluated the taxonomic distances between the black soils of the Russian classification, the Great Groups of the Mollisol order of the Soil Taxonomy and corresponding Reference Soil Groups with similar properties of the World Reference Base. With the process, we performed the taxonomic distance calculations using centroids which are the calculated mean values for several soil properties for each of the soil groups using legacy data derived from national and international databases. The results indicated that the Great Groups of the Mollisol Order in the 21 US Soil Taxonomy had small taxonomic distances between the order, except the soils with shallow depth to the rock, hardpan, or permafrost. The soil types of the “black soils” of the Russian soil classification had a short distance to the corresponding Reference Groups of the World Reference Base, and the relationship was well correlated from a pedogeographic point of view. However, both the Reference groups of the World Reference Base and Russian soil types had large taxonomic distances from the Soil Taxonomy Great Groups. We ascribed the difference to the geographical bias of the databases. Though “black soils” form a distinct cluster 28 that roughly corresponds to the Mollisol Order of the US Soil Taxonomy, the taxonomic distance within the group may be significant, contributing to the pedodiversity of soilscapes with “black soils”.