Chapter 6 Modern Soil Classification Systems Logical and Cognitive Science in Soil Science • What are we trying to do? • How are we going to do it? • What standards must be established? Soil Classification • Organize soil categories for efficient information – Storage – Retrieval – Communication • Parent material origins and genetic information help guide Cognitive Science Classification Soil Classification • How do we classify soils? – Cognitive Economy – provide maximum information with least cognitive effort – Population Structure – what is important to us and why? – Expertise effect – recognized experts in area of study will influence to their benefit – Culture and Environment -dependant on location, different features maybe placed on higher level of importance – Prototype Concept – collection of samples to determine what are categories Indigenous Soil Classification • Local or Folk Classification – No formal categorical structure – Limited geographical scope – Focused on production soils • Beneficial for relating knowledge to local communities Regional and National Soil Classification Systems • Early European System – – Strongly influenced by Russians – Used chemical analysis approach – Low emphasis on Bt Horizon (B horizon with an accumulation of silicate clays) – Centuries worth of continuous use – Kubiena System (1953) – focuses on moisture, chemical properties, humus type, pedogenic processes, and micro morphology Russian Soil Classification • Started by Dokuchaev and Sibirtsev • Uses strong genetic (parent material emphasis) and pedogenic processes • Hierarchical structure includes – – – – – – – – Trunk Section Type Subtype Genus Class Subclass Sort Russian Soil Cont. • Trunk – Postlithogenic – soils formed on previous parent material with negligible modern accumulation on the surface – Synlithogenic – soils formed with periodic or continuous accumulation of new material on the surface – Organogenic – soil formation on organic material Dutch Soils • Half of the country is below sea level and is protected by dykes and dams • Intensively cultivated • Sandy and Peat type soils • Classifications – Order – Suborder – Group – Subgroup New Zealand Soil • Structured after US System, but developments in Andisol and Inceptisol series drove New Zealand to develop own system. • Contain only soils in New Zealand • Contains 15 orders focusing in on volcanic activity focusing on Allophanic and Pumice soils Canadian Soil • A system that is used only to classify soils present in Canada • Hierarchy includes – Order – Great Group – Subgroup – Family – Series • 10 orders and 31 great groups Canadian Soil • Order – soil properties reflecting the effects of the dominant soil-forming processes and the soil environment • Great Group – properties reflecting the strength of dominant pedogenic processes in addition to the major one • Sub-group – taxa based on congruence with the central concept of a group and the associated kind arrangement of horizons • Family – taxa seperated on the basis of minerology, texture, and climatic factors within each family Aussie Soil • • • • Wide range of soil Wide range of climates Wide range of precipitation Hierarchy – Horizon Pedounit – a combination of similar horizons – Group – a collection of pedounits that are similar to soil mapping characteristics equivalent to US soil series – Subclass – groups placed together because of similarities in two or three kinds of horizons – Class – highest level of generalization Brazilian Soil • 13 Classes • Based of the 1938 US soil series • Emphasis placed on chemical aspects because relative low fertility and focus on soil amending Chinese Soil • 33 horizons • 25 diagnostic properties – Soil temperature – Soil moisture regime • Focus on soils which have been cultivated for thousands of years in flood irrigation of rice paddy • Incorporates indigenous names and current to improve understanding World Reference Base • An effort to standardize world wide soil taxa • 32 groups • Next tier has group of prefixes and suffixes to modify terms Numerical Classification of Soils • Ideal natural taxonomy is one in which taxa have greatest information • Every natural feature is of equal wieght in construction • Affinity is a function of proportion of features in common • Affinity is independent of phylogeny (evolution) • Negatives – Potential loss of information – Selection, measurement, and coding are subjective – Complex Indigenous Soil Classification