Soil profile distribution of water repellency and relationships with properties and characteristics of Technosols from open-cast mining

Irena Atanassova, Plamen Ivanov, Toma Shishkov, Emil Dimitrov and Martin Banov

Abstract: The present paper presents a study of soil water repellency in Technosols, formed on spoils with Pliocene clays after open-cast mining in the area of Maritsa-Iztok Mines, Bulgaria. At present, different soil properties and characteristics have been studied in areas of the mine spoils from Obruchishte village to establish their relationships with soil hydrophobicity and its spatial distribution in the surface and subsurface soil layers. To obtain complete information, the present study characterizes soil water repellency in vertical direction by assessing the similarity and differences in its appearance in depth of the soil profile. The effect of laboratory heating on hydrophobicity in the individual soil layers has been assessed. Extreme water repellency (water drop penetration time (WDPT) 10160 – 13391 s) is found in the 10–80 cm depth of the soil profile, which decreases abruptly after laboratory heating of the soil samples. Extreme acidity pH and high carbon content are reported. Assumptions for the presence of impurities of coal particles in the substrates were checked. Humic organic carbon correlates positively with water drop penetration time (RWDPT-HOC = 0.440*), which confirms its determination so far, as one of the main factors influencing the soil water repellency in the studied technogenic soil profile. A significant correlation between residual fraction of soil organic matter and clay (< 0.001 mm) in soil layers (Rclay- C res. = 0.579**), as well as regarding cation exchange capacity (RCEC- C res. = 0.433*) was found.

Keywords: soil organic matter; soil profile; soil water repellency; Technosols; water drop penetration time

Date published: 2020-10-19