Soil Conditions

 

A relatively wide spectrum of soil units have developed on the relatively small territory of the Podyjí NP, and these are concentrated in the predominantly forested areas, which make up around 84% of the total national park area. According to the currently valid “Taxonomic Classification System of Soils in the Czech Republic” (Němeček and Coll., 2001) the most represented category (more than 1/3 of the total area) are Oligotrophic and Mesotrophic Subvarieties of Cambisols (Brown Soils). These have developed on the acidic effusive and metamorphosed bedrocks (granites, granodiorites, gneisses, mica schists, phyllites, conglomerates, sands, sands and gravels) and the majority of these soils are shallow–medium depth, of small–medium grain size, stony (gravelly) in places, with low-medium nutrient levels and water-saturated in a few places. These soils cover the Dyje canyon, where they alternate with very shallow, skeletal and fast-drying Rankers and Lithosols (undeveloped soils), and also in the wider surroundings of the canyon. Rendzinas, which are humus-rich soils with a higher percentage of carbonates throughout the profile, have only developed on the weathered crystalline limestone close to the Hardegg border crossing. Deep soils of the brown earth and Luvisol types (Sod-Podzolic soils), with considerable evidence of waterlogging, which are medium heavy-heavy, without skeletal content and with high nutrient levels have developed on the blankets of loess and loess loams in the south-western and north-western corners of the national park and to the east of Podmolí. Periodically waterlogged Pseudogleys (gley soils) have developed on small areas (around 1% of the NP), on a base of polygenetic loams – especially between the villages of Lesná and Lukov. Narrow belts of Fluvisols (alluvial soils) and permanently waterlogged Gley soils have developed on the non-calcareous alluvial sediments around the smaller streams.

Agricultural lands cover around 16% of the total area of Podyjí NP. These are mostly covered with Cambisols on the acidic and neutral effusive and metamorphosed bedrocks, but form a narrower spectrum of varieties and subtypes when compared with the forest Cambisols, which are close neighbours with these forest-free agricultural zones. These are medium depth, quite heavy-light soils under permanent grassland cover, with low-medium nutrient levels and local waterlogging. The second most widespread soil type on the agricultural lands are brown earths on the loess and loess loams, and also on the polygenetic loams in places, with an admix of carbonate materials, and are mostly found all the way along the northern border of the national park. These are fertile and productive soils with good-high nutrient levels, but have a tendency to become waterlogged as a result of the grain heavy structure of the subsoil layer. In addition to the brown earths, Luvisols have also developed on the coarser-grained loess-and polygenetic loams. The most fertile soil in the national park is the deep, medium-heavy Chernozem (black earth), which is eroded in places and without skeletal content, has developed on the loess on a small area along the eastern and south-eastern border of the national park. Narrow belts of Fluvisols have developed on the non-calcareous alluvial sediments along the Dyje river and its tributary streams. These are accompanied in a few places on the non-calcareous deluvial sediments by Gley soils.

On the basis of the inventorisation of soil contamination by heavy metals and dangerous substances, and polycyclical aromatic hydrocarbons (PAH) in Podyjí NP, which was carried out in 1996 by the Agency for Nature Conservation and Landscape Protection, and from the available results of the monitoring of the pollution of agricultural soils by the Central Institute for Supervising and Testing in Agriculture in Brno, which involved 90 soil samples, no limits for the content of selected heavy metals and dangerous substances (Cd, Co, Cr, Cu, Ni, Pb, V and Zn) were exceeded. The acceptable limits (natural content) for selected PAH pollutants (Ministry of the Environment Decree No. 13/1994 Coll.) were only exceeded in the surroundings of Znojmo and along the road from Znojmo to Vranov nad Dyjí. The limits for these pollutants were not exceeded anywhere else in the national park. This evidence indicates that Podyjí NP is one of the least polluted protected areas in the whole Czech Republic.

From the standpoints of soil vulnerability, and the soil´s relationship to heavy metals and dangerous substances, the most widespread soil types (which cover around 70% of the park area), belong to the highly vulnerable category (No.4) (Podlešáková, 1992), which mostly includes light, shallow and acidic – highly acidic Cambisols to Rankers. These are characterised by a reduced capacity to bind to heavy metals and dangerous substances and a reduced resistance to the effects of acidic precipitation, meaning that they have a notable tendency towards acidification. On the other hand, the soils in the 1a and 1b classes display low vulnerability, as they have an increased to high capacity of binding to heavy metals and dangerous substances, as they contain clayey minerals and humus, and are highly resistant to acidification. These categories mostly include the agricultural soils (black earths, brown earths) with a low risk of contamination as the plants absorb heavy metals and dangerous substances from the soil.

The soil in the national park is at risk from water erosion, although wind erosion is less significant. These endangered soils are predominantly light and skeletal soils on the steep slopes and cliffs of the Dyje canyon and its deeply-incised side valleys. The soil cover of light soils on slopes of less than 5° and of medium-heavy soils on slopes of less than 6 - 10° are less at risk of erosion.

 

Author: Martin Škorpík