Black Soils Outside of the INBS Criteria in Slovakia

Abstract

The distribution of black soils in Slovakia can be divided into the two basic groups: distribution of black soils according to the International Network of Black Soils (INBS) and distribution of black soils outside of the INBS specified criteria. Black soils outside of the INBS criteria on selected soil profiles are evaluated in this contribution. Indicators of black soils outside of the INBS criteria are very common in comparison with the first group – existence of mollic horizon – but the depth of mollic horizon is often less than 25 cm where the soil properties are practically the same as in black soils using the INBS criteria (represented by Chernozems and Phaeozems). Other special group of black soils without mollic horizon can be also included in the “black soils” category with low soil reaction (pH/H2O < 5.5 and pH/KCl < 5.0), low base saturation (< 50%) with high content of SOM (10–20%) represented mostly by Andosols and Umbrisols in Slovak conditions. The aim of this paper is to emphasize the significance of black soils outside of the INBS criteria on selected examples of soil profiles in Slovakia. The basic chemical (pH/H2O, pH/KCl, soil organic carbon (SOC), total nitrogen, humic acids, fulvoacids, colour quotient Q46, available nutrients P and K, melanic index) and physical (fractional mechanical composition) procedures were conducted in NPPC – Soil Science and Conservation Research Institute in Bratislava. Based on the obtained results, the black soils outside of the INBS criteria in Slovakia belong mostly to the most fertile soils with the existence of mollic horizon but often shallower than in black soils according to the INBS criteria (< 25 cm) and cultivated mostly as arable land (represented by Chernozems and Phaeozems). Only a smaller part of these soils – without mollic horizon (Andosols, resp. Umbrisols) – belong to the soils with low fertility and are mostly situated in forest protected areas on some volcanic rocks, especially with the occurrence of volcanic glass. Total area of these soils is about 8.7% of soil cover in Slovakia. All the groups of black soils (within and outside of the INBS criteria) have to be strongly protected.