The article analyses the effect of sewage sludge application on the content of total nitrogen and its mineral forms (NH₄⁺, NO₃⁻) in light cultivated soil, indicating the potential of sewage sludge as a source of nitrogen and the environmental risk associated with its excess. The study was conducted in a 3-year pot experiment. The light soil was fertilized with sewage sludge at fertilizer (10 Mgꞏha-1) and reclamation (100 Mgꞏha-1) rates applied alone and with the addition of mineral wool. The study showed that fertilizing light soils with sewage sludge, especially at a high rate combined with mineral wool, effectively increased organic matter and total nitrogen. The high total nitrogen content persisted throughout the study period. The dose of applied sludge had an impact on the content of mineral forms of nitrogen in light soil. The highest values of NH₄⁺ and NO₃⁻were observed in soil fertilized with sludge reclamation dose. No significant increase in the proportion of mineral forms of nitrogen in its total content was observed. The addition of mineral wool in combination with sewage sludge further enhances the fertilizing effect, which can be practically used for the reclamation and enrichment of soils with low humus content.