Relationships between soil water repellency, physical and chemical properties in hydrophobic technogenic soils from the region of Maritsa-Iztok Coal Mine in Bulgaria

N. Poushkarov Institute of Soil Science, Agrotechnologies and Plant Protection, Sofia, Bulgaria


Atanasova, I. M. Banov, T. Shishkov, Z. Petkova, B. Hristov, P. Ivanov, E. Markov, I. Kirilov and M. Harizanova, 2018 relationships between soil water repellency, physical and chemical properties in hydrophobic technogenic soils from the region of Maritsa-Iztok coal mine in Bulgaria. Bulg. J. Agric. Sci., 24 (Suppl. 2): 10-17

Soil water repellency (soil hydrophobicity) is considered a key mechanism for sequestration of organic carbon. Technogenic soils from mine areas containing clays and irregularly distributed lignitic particles are heterogeneous materials exhibiting small-scale spatial variability of water repellency. Non-vegetated and pine-afforested spoils from the area of Maritsa-East lignite coal basin in Bulgaria were studied. The technogenic soils were characterized by severe to extreme hydrophobicity and heavier texture at the pine-vegetated site, as well as extreme acidity (pH 3-4). Principle Component Analysis (PCA) and cluster analysis were carried out, in order to study the simultaneous interaction of soil characteristics and properties with the aim to assess their role in the overall data variability in the process of data reduction to several unrelated components. The PCA was based on twelve factors: WDPT, sand, silt and clay contents, hygroscopic moisture, cation exchange capacity (CEC), organic carbon (total organic carbon TOC, humic organic carbon HOC and fulvic organic carbon, FOC), total nitrogen (N) and mineral nitrogen (MN) and electrical conductivity (EC). Three principle components were identified with eigenvalue > 1, describing 79% of the total variability. There was a significant positive correlation between WDPT and TOC, HOC, FOC, MN and a negative correlation with the % of hygroscopic moisture. The results obtained indicate that TOC comprised mainly of particulate organic carbon (POC) containing coal particles was significantly correlated with the sand fraction, CEC and MN, and was the main driver of soil water repellency in the studied mine soils.

Keywords: soil water repellency, technogenic soil, mine, soil properties, principal component analysis
Abbreviations: WDPT – Water Drop Penetration Time, OC – Organic Carbon, CEC – Cation Exchange Capacity
SWR – Soil Water Repellency, SOM – Soil Organic Matter, TOC – Total Organic Carbon, HOC – Humic Organic Carbon, FOC – Fulvic Organic Carbon, EC – Electrical Conductivity, MN – Mineral Nitrogen, PCA – Principle Component Analysis, CA – Cluster Analyses, PC – Principal Components

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