Fragipan in Slovakia and possibilities of its inclusion in the soil classification system

Abstract

The fragipan horizons due to their high bulk density significantly affect the water infiltration and retention in soil. They significantly influence the hydrophysical properties of the soil, the plant´s roots, and all processes taking place in the soil – water – plant system. However, up to now in Slovakia fragipan horizons were not recognised and they were not considered in Slovak soil classification. In last period this question starts to be discussed and there is emerging demand to investigate the occurrence of fragipan horizons in Slovak soils. This paper aims on identifying fragipan horizons in several locations in Slovakia based on field research and to define basic criteria for their diagnostics in the classification system. All available information on fragipan horizons existing so far in Slovakia was reviewed and a correlated with the USDA Soil Taxonomy. The results of the survey pointed out that fragipans are typically associated with two soil types – Pseudogleyic Luvisol and Luvic Pseudogley. They are characterized by a gradual increase in the clay content with depth and the collapse of soil structure (they are brittle) in connection with a significant decrease in porosity and the content of non-capillary pores. Significant feature is the absence of structural pores other than planar pores of large prismatic aggregates. The results of this paper provide database and photographic documentation, which allows us to consider inclusion of fragipan into the new updated version of the Morphogenetic Soil Classification System of Slovakia, which is recently in preparation phase.

Keywords: fragipan, soil classification, hydro-physical properties