Soil Taxonomy Proposals for Acid Sulfate Soils and Subaqueous Soils Raised by the 8th International Acid Sulfate Soils Conference
The 8th International Acid Sulfate Soils Conference presented examples and discussions for classification of ‘acid sulfate soils’ and related issues for ‘subaqueous soils’. When these soils are disturbed or exposed, the sulfides (predominantly pyrite) react with oxygen to produce sulfuric acid; soil materials that do this to a great extent are recognised as ‘sulfidic materials’ in Soil Taxonomy. Soil Taxonomy describes physical and chemical properties and thresholds for incubation of sulfidic materials for acidification, and has developed definitions for features and materials commonly seen in these soils. However, based on discussions and examples from field tours the conference has several proposals to modify and add to existing definitions, such as adding new subgroups, defining sulfuric materials and editing the definition of the sulfuric horizon. These changes are centred on improving the interpretative value of taxa in Soil Taxonomy as well as use and management recommendations and their value in soil survey products.