This research reports and analyzes results of a field experiment started in 1984, when hard coal fly ash (HCFA) was added to soil at doses of 0 to 800 Mg·ha^-1. During the first years of the experiment, traditional crops were grown in the plots, which in 1992 were converted into permanent grassland. Twenty-nine years after the application of fly ash, soil samples from the 0-20 cm soil layer were collected to determine chemical properties of soil. The results showed an elevated soil reaction, and high contents of available forms of P, K, and Mg, plus mineral forms of nitrogen and high soil organic matter. Under increased ash doses, analysed soils increased the C:N ratio and shares of N-NO₃ and N-NH₄ in total nitrogen content. These results justify that fly ash from combustion of hard coal in a power plant can produce long-term impact on soil, contributing to a certain improvement of its chemical, physical, and biological properties, which stimulate the sequestration of carbon in soil.