Soil physical properties of agriculturally reclaimed area after lignite mine: A case study from central Poland

• Reclamation variants diversely influenced the physical state of technogenic soil.
• All soils had favourable values of macroporosity and water available for plants.
• Application of lignite resulted in the lowest air and water permeability.
• Spontaneous succession contributed to the most preferred soil physical state.

For the assessment of the extent of post-mine land degradation, arranging management practices for sustainable land use, and evaluation of reclamation success research on soil physical properties plays a significant role. The aim of this study was to quantify and interpret the effects of varied agricultural reclamation methods in order to assess which of the treatments yielded higher soil quality with respect to its physical state. Basic physical and chemical parameters (texture, particle and bulk density, total porosity, total organic carbon and pH), soil water characteristic curves, water and air permeability, structure of the soil damaged by mining in the area of internal dumping ground Pątnów (Central Poland) were therefore measured. The soil samples were taken from the following 5 different variants of over 30-year-long reclamation: black fallow (BF), monoculture of winter wheat (WW), monoculture of winter wheat with a single application in 1992 of lignite dust (WW + L), monoculture of alfalfa with orchard grass in the proportion of 90/10% (A + G), and spontaneous succession (SS). We collected from each treatment: 12 soil cores for soil water and air properties; 6-kg composite bulk samples for basic physical and chemical properties of soil; 1 undisturbed soil block for structure analysis. The reclamation methods applied on the post-mining grounds influenced in a diverse manner the physical state of the 0–10 cm layer of the developed technogenic soil. Bulk density values generally decreased with the increase of number of factors potentially loosening the soil structure. The studied plots had sandy loam or loamy sand texture which determined their overall air and water properties. The soils were characterized by high macroporosity and favourable content of water available for plants. Less beneficial conditions of the soil were associated with air and water permeability. The present studies indicated that spontaneous succession, with the highest typological diversity of vegetation, contributed to the most preferred soil physical state. Remaining variants of reclamation (including black fallow without vegetation) also provided sufficient air and water relations in the soils. However, it should be emphasised that plants play an important role in TOC accumulation and ensuring relative stability of soil structure. Therefore rehabilitation of post-mining grounds involving vegetation is recommended.

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