Pedochemical evaluation of soils, characterizing the pastoral localities of the National Nature Reserve Mohelno Serpentine Steppe. II. The content of potentially risk elements and micronutrients

The aim of our paper is primarily to characterize the contents of chromium, nickel and cobalt in the "serpentine soils" of the National Nature Reserve Mohelno Serpentine Steppe. A part of this reserve area (permanent grassland) is used for sheep and goats grazing in order to maintain and expand xerothermic plant and animal communities, while respecting the specific (in particular qualitative) animal feed requirements (forage). Increased concentrations of Cr, Ni and Co are typical for serpentine soils, and it is necessary to verify the probability of the risk accumulation of Cr, Ni and Co in above-ground biomass of pasture in particular. The analysis of (pseudo)total soil form of Cr, Ni and Co (aqua regia extract) within representative pasture areas shows their content on average 515 mg/kg, 1,318 mh/kg and 112 mg/kg, resp. Hence, so called Preventive values for Cr, Ni and Co have been exceeded almost 6-fold and nearby 4-fold, resp. Simultaneously, the Trigger value indicating the posiible risk of given element entering the food chain with a negative consequence for the crop, or for the consumer, was exceeded only for Ni. In the Aqua regia soil extract has been this Trigger value exceeded approximately 7 times and simultaneously in the 1M NH4NO3 extract (i.e. biomobile form) 4 times. Taking into account the contribution of biomobile soil fraction to (pseudo)total one, and simultaneously the legislative criteria, it can be assumed that only nickel may accumulate more significantly in above-ground biomass of permanent grassland. On the other hand, analysis results of Cu, Fe, Mn and Zn soil content within the same areas do not lead probably to suspicion of an increased uptake of these elements by above-ground biomass.