Phytoremediation potential of biochar in the context of soil reclamation after hydromechanized ilmenite mining

Purpose. The aim of this study is to substantiate the effectiveness of biochar as a sorption-buffer additive for agroecological reclamation of soils degraded due to hydromechanized ilmenite mining. Methodology. Four representative soil samples were collected within the reclaimed tailings of the Valky section of the Hatskivske deposit, each quartered into laboratory samples weighing 0.5 kg. Biochar (pyrolytically carbonized biomass) was added to three samples in proportions of 5%, 10%, and 15%. The fourth sample received a combined additive of 5% biochar and 5% sphagnum peat. After thorough mixing, initial pH values were measured, followed by monitoring at 14-day intervals over a period of 42 days. Results. An increase in pH over time was observed in all four samples. The most significant rise occurred with the 15% biochar addition, while the 10% and 5% doses were less effective. The combination of 5% biochar and 5% peat produced an effect comparable to the maximum biochar dose, indicating synergy, thus enabling reduced material usage without compromising effectiveness. Scientific novelty consists in the first quantitative evaluation of biochar efficiency for the reclamation of ilmenite tailings, and the identification of a synergistic effect from its combined application with peat. This allows for reduced usage of carbonized biomass without loss of buffering activity in alluvial-eluvial sandy-loamy substrates and demonstrates the potential for heavy metal stabilization under these conditions. Practical significance lies in developing technological recommendations for mining enterprises regarding the application of biochar. These guidelines ensure rapid soil restoration and improvement of hydro-physical soil properties, shortening reclamation cycles and reducing the cost of land restoration, thus making reclaimed lands suitable for agricultural use and mitigating anthropogenic environmental impacts. Key words: biochar, phytoremediation, soil reclamation, ilmenite tailings, soil acidity, peat.