Fjölrit RALA - 15.06.2004, Side 151

Soils developed on volcanic material and their erodibility in Hungary
B. Madarász, Á. Kertész
Department for Physical Geography, Geographical Research Institute, Hungarian Academy of Sciences
Volcanic activity took place in two main phases in the Carpathian Basin. The older phase
occured in the Middle Miocene approximately 20 to 10 million years ago. This phase can be
characterised by calc-alcaline silicic pumice and ash flow deposits (ignimbrites), and
andesite-dacite lavas. The Pliocene-Pleistocene phase produced alcaline basalt lavas and tuff.
This phase began some 7 million years ago and finished only about 500 thousand years ago.
The absence of typical Andosols in Hungary can be explained by the relatively old volcanic
material in the region.
In the framework of the COST 622 action in Hungary three soil profiles were selected for
detailed analyses. These profiles represent different types of volcanic bedrock because of the
large variety of soils developed on volcanic rocks.
Brown earth (Cambisol) can be found in the lower areas, mostly on pumice-and-ash flow
deposits. Forests soils are present in the mountainous region, where the parent material of the
soil is mainly lava or block-and-ash flow deposit. The most common forest soil is the
lessivated brownforest soil (Luvisol).
The soil type closest to the Andosols in Hungary developed either in hilltop or in pediment
position. The hungarian soil-classification system calls this soil erubáz■ People call it black
wet soil, which refers to its dark colour and high clay (mostly smectite) content. The erubáz
soils are caracterised with an intense humification, almost neutral pH values, friable or
polygone structure and they are weakly leached. Their water retention capacity is very low
and their heat-regime is extreme. In springtime their water content is high, which decreases
rapidly in the first part of the summer.
Majority of the Hungarian wine-regions are situated in volcanic areas with erubáz or
erubáz-like soils, therefore the cultural and economic significance of this soil is considerable.
According to the COST 622 analyses, these soils proved to be similar humic Umbrisols.
On hillsopes and pediment surfaces these soils can be significant by erodid. The erodibility,
or K-factor is determined according to the USLE method (WlSCHMEIER and Smith 1978) by
Copecki rings. The results of these measurements are expected for May 2004.
References
Wischmeier, W.H., and D.D. Smith. 1978. Predicting rainfall erosion losses. A guide to
conservation planning. USDA Agriculture Handbook. No. 537. Washington
Stefanovits, P. 1992. Soil Sience (in Hungarian, Talajtan), Mezögazda Kiadó
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