Alders, as an N-fixing species, are widely used as a phytomelioration species at post-industrial sites. The paper presents the effects of litter decomposition of different alder species-black alder, gray alder, and green alder-on changes to the soil solution chemistry of Technosols developed from two types of substrates: lignite combustion waste and sandy substrates from a former sand quarry. Under controlled conditions, the 13-week experiment investigated pH, electrical conductivity (EC), and the chemical parameters-dissolved organic carbon (DOC), dissolved nitrogen (DON), and macroelements S, Ca, Mg, K, and Na content-of filtrates in composites consisting of substrate and litter from alder species was investigated. Alder litter accelerated nutrient leaching processes from soil substrates and had the greatest impact on sandy substrates because fast leaching was possible at low absorption capacity characteristics. Higher leaching rates in sandy substrates were also observed, especially in the cases of DOC, DON, K, and P, in comparison to combustion waste substrates. In the first phase of the experiment in sandy soil substrates, the dominant process is the leaching of DOC from dead organic matter, while in the case of combustion waste, calcium leaching prevails in the first phase. Among the investigated species, black alder had the greatest impact on the chemistry of substrates and solutions, and the dynamic of these processes has a different path at various substrates.
Keywords: Dissolved carbon; fly ash; litter decomposition; reclamation; soil solution chemistry.