Soil is a very important natural feature for human existence. It represents a geochemical sample medium, which determines the contents of soil components that can be of natural or geogenic origin, but they can also be a result of human activity. The composition of soils is very similar to the one of the rocks. Therefore, parent material is the most important factor for chemical composition of soil. Due to the wide range of sampling purposes, it is impossible to give uniform guidelines on the method of soil sampling, as the method of sampling depends on the purpose of the examination. Unfortunately, the different sampling approaches are not completely comparable. Using several types of parent material, soils were sampled from soil profiles by horizons (pedological sphere) and from the upper 15 cm of soil (geological sphere). Our goal was to find the differences in soil chemistry. We used calculations and graphs to represent the best characteristics of both approaches.
A very good match was observed for most oxides (SiO2, Al2O3, Fe2O3, MgO, CaO, Na2O and K2O). The depth sampling method for potentially toxic elements (As, Cd, Co, Cr, Cu, Ni, Pb, Zn) gave us slightly lower values compared to the horizon sampling method. The largest differences between the two approaches were noticed for Cd. The most significant deviations were found in P2O5 and TOT/C due to binding to organic matter. The increased content of organic matter in the sample material results in a poor match between the approaches in all cases, but most visibly in the sampling point with the highest amount of organic matter (Osankarica - Kebelj). Both approaches correctly reflect the geochemical and mineral characteristics of the parent material and also point out the increased amounts of potentially toxic elements. We found that good cooperation between the pedological and geological departments is key in any sampling, as determination and knowledge of the horizons is crucial in interpreting the results.
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