Saturday, 15 July 2006

National Classification of "Chernozem like" (steppe) soils and their correlation with the WRB.

Gabriella Sz Kele, Plant Protection and Soil Conservation Service, Ország út 23., Velence, 2481, Hungary, Erika Micheli, Szent Istvan University, Soil Science and Agrochemistry Department, Pater K. u. 1., Godollo, 2103, Hungary, and Judit Berényi Üveges, Central Service for Plant Protection and Soil Conservation, Budaörsi út 141-145, Budapest, 1118, Hungary.

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

“Chernozem like” soils are the most important and fertile agricultural soils of Hungary. They are distinguished from other units based on their humification processes / status, their natural high base content and the morphological evidences of high biological activity. These soils belong to the “csernozjom main type” in the Hungarian Soil Classification System (HSC). In general characterization dark and high organic matter content top horizon is a requirement for the unit, however there is no numerical limit set for the % and depth. On the lower level of the classification, units (subtypes) are separated based on the presence and distribution of secondary CaCO3, the influence of ground water and inherited alluvial features. Subtypes are further classified based on the presence of soluble salts. These listed features also lack the definitions and limits, making decisions subjective for the classifier.

In the World Reference Base for Soil Resources (WRB) most of the steppe soils belong to the Kastenozems, Chernozems and Phaeozems reference groups. All three require the presence of a mollic diagnostic horizon with well defined criteria for colour, organic matter content, base saturation, structure and depth. Many of the Hungarian “csernozjoms” fail one or more of those criteria and may key out as Cambisols or even Regosols in the WRB. The lower level correlation of the subtypes has also very broad choices, since gleyic properties and depth requirements are not defined. The same situation is with the lack of definition and depth requirements of fluvic soil material and secondary calcium carbonate accumulations.

The poster will give examples (with pictures and data) for the Hungarian csernozjoms units and will discuss their classification and correlation problems with the WRB.

Suggestions will be provided for the improvement of the classification of Hungarian csernozjoms, including changes and/or introduction of definitions and limits of horizons, properties and materials and the newly constructed key. It will be demonstrated that the new terms, definitions and limits were developed (to the extent possible) in harmony according to WRB, to allow better correlation. At the same time suggestions for new qualifiers in the WRB will be presented for better characterization of steppe soils.

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