Physical and soil water properties of technosols developed from lignite fly ash

The aim of this study was to determine the influence of reclamation on selected soil water properties in soils developed from lignite fly ash, deposited as a dry landfill, twenty years after forest reclamation was initiated. Five soil profiles, classified as technogenic soils (Technosols) within the fly ash disposal site of the Adamów (central Poland) power plant, were selected for this study. Disturbed and undisturbed samples (V=100 cm3) were collected from depths of 5–15 cm and 30–60 in each soil profile. The following physical properties were determined: particle size distribution, particle density, bulk density, soil moisture, hygroscopic water content, and the soil-water potential. Readily available water (RAW; difference of water content at pF=2.0 and at pF=3.7) and total available water (TAW; difference of water content at pF=2.0 and at pF=4.2) were calculated based on soil moisture tension (pF) values. The following chemical properties were determined: soil reaction, total organic carbon, total nitrogen content, carbonate content. Statistical analyses were conducted using the GenStat 18 statistical software package. The soils under study were characterized by very low bulk density, high total porosity, high field water capacity and maximum hygroscopicity. The RAW/TAW ratio values indicate very effective water retention in the soils, thereby ensuring a satisfactory water supply to the plants. However, statistical analysis did not show any clear trends in variability of any determined properties. The small differences in observed outcomes probably resulted from the original variability of the fly ash deposited on the studied landfill. Obtained results show the strong similarity of fly ash derived soils and Andosols in respect of physical and soil-water properties