Assessment of the structure, composition, and agrochemical properties of fly ash and ash-and-slug waste from coal-fired power plants for their possible use as soil ameliorants

Coal combustion byproducts—fly ash (FA), bottom ash (BA), and ash and slag waste (ASW)—are of considerable interest for the development of their application as soil ameliorants since these harmful wastes are produced in large quantities and need to be utilized or processed. Moreover, if FA is studied quite well in this respect, much less data exists on the BA and ASW, with fewer opportunities for their other economically justified use. Thus, this research focused on the possibility of FA and BA (ASW) application as soil ameliorants. Ash samples from power plants in European Russia were selected since they are not studied in detail before. To estimate the impact of ash application, changes in key indicators reflecting the soil quality, its suitability for growing safe products were assessed: particle size distribution , acidity, nutrient, and potentially toxic elements (PTEs; heavy metals and metalloids) concentration, and their potential availability for plants. The application of ash samples to soddy-podzolic soil contributed to pH normalization, confirming the possibility of using these wastes as a stabilizer of soil acidity at the optimum ratio of ash to the soil of 1:2 or 1:5. ASW samples can aggregate with soil particles, contributing to agrophysically valuable aggregates 250–2000 μm. Despite the contents of PTEs, ASW can be considered a safe material as the legislatively established standards are not exceeded.