Classification of acid sulphate soils of Finland according to Soil Taxonomy and the FAO/Unesco legend

Authors

• Markku Yli-Halla Agricultural Research Centre of Finland, Institute of Resource Management, FIN-31600 Jokioinen, Finland

DOI: https://doi.org/10.23986/afsci.72788

Abstract

In order to place acid sulphate soils (a.s. soils) of Finland in an international context, five pedons from cultivated a.s. soils from Liminka, Ylistaro and Laitila on the western coast of Finland were analyzed and classified according to Soil Taxonomy and the revised legend of the FAO/Unesco Soil Map of the World. Three of the pedons (Liminka 1 and 2, Laitila 1) had sulfuric horizons within 50 cm of soil surface and qualify as Typic Sulfaquepts. One pedon (Ylistaro) had a sulfuric horizon at the depth of 100-150 cm and was classified as a Sulfic Cryaquept. The fifth pedon (Laitila 2) did not have either a sulfuric horizon or sulfidic materials, but it had a pH<4.0 and enough SO4-S to be classified as a Sulfic Cryaquept. According to the FAO/Unesco legend, all pedons were classified as Thionic Gleysols. Thus Typic Sulfaquepts and Sulfic Cryaquepts (Soil Taxonomy) and Thionic Gleysols (FAO/Unesco classification) occur commonly on the western coast of Finland. As a result of artificial drainage and leaching, they gradually fail to meet the requirements of a.s. soil classes and will be classified as Typic Cryaquepts. In terms of the FAO/Unesco nomenclature, Thionic Gleysols become Dystric Gleysols or Gleyic Cambisols over time.