Saturday, 15 July 2006

National Classification of “Hydromorphic” and Salt affected soils and their correlation with the WRB.

Marta Fuchs1, Erika Micheli1, Peter Hegymegi1, and Tibor Tóth2. (1) Szent Istvan University, Soil Science and Agrochemistry Department, Pater K. u. 1., Godollo, 2103, Hungary, (2) Research Institute for Soil Science and Agricultural Chemistry of the Hungarian Academy of Sciences, Herman O. u. 15., Budapest, 1022, Hungary

This poster is one of a series discussing the classification and correlation problems of soils of Hungary.

“Hydromorphic” soils are referred to as “azonal” soils that were formed under the influence of high ground water. Those that are influenced by ground water without high level of soluble salts belong to the “meadow soils” main type, those that have developed under the influence of groundwater containing high levels of soluble salts belong to the “salt affected soils” main type in the Hungarian Soil Classification System (HSCS). Although the influence of ground water is the differentiating criteria for meadow soils, gleyic properties and depth requirements are not defined making the separation from other units subjective. On the lower levels (types and subtypes) of classification, units are separated based on humification rate, presence and distribution of secondary CaCO3, inherited alluvial features and the presence of soluble salts in deeper horizons. These features also lack precise definitions and limits. In the WRB, soils influenced by ground water level are defined by “gleyic” properties at a shallow depth. In the WRB reference group, Gleysols, well developed soils are excluded. They are identified with the “gleyic” modifier in other reference groups.

Correlation of the Hungarian meadow soils with the WRB is difficult and allows several alternatives because of the missing definitions and limits. Further confusion is created by the fact that many of the meadow soils are heavy clay soils that satisfy the criteria of WRB Vertisols, while in the current HSCS there is no separate unit for high clay content soils.

Distinguishing salt-affected soil in the HSCS is less of a problem, as the limits for amount, depth and type of soluble salt are well defined. Correlation with the WRB, however, is a problem because methods of determination and limits of parameters are not the same.

The poster will give examples (with pictures and data) for the Hungarian meadow soil and salt affected soil units and will discuss their classification and correlation problems with the WRB. The conflict of national traditions with the need for harmonization with the WRB will be discussed. Suggestions will be provided for the improvement of the classification of Hungarian meadow soils with introduction of definitions and limits of horizons, properties and materials. A suggestion for the addition of a Vertisols unit and related diagnostics into the HSCS will be presented as well as suggestions for introduction of additional qualifiers in the WRB for better characterization of these soils.

Back to RB Developments in the World Reference Base (WRB), Soil Taxonomy (ST) and Other National Soil Classification Systems for Soil Resources - Poster
Back to WCSS

Back to The 18th World Congress of Soil Science (July 9-15, 2006)