Physico-chemical properties of biomass ashes and biochar were significantly different. Strong differences were also caused by the choice of feedstock materials for incineration, which is demonstrated by different composition and solubility of wood and straw ashes. Availability of nutrients was the highest for K among all tested macronutrients. The application of ash did not adversely affect the growth and yield of plants, neither the accumulation of nutrients in plants and soil. The inoculation of soil by bioeffectors did not affect plant yield but positively influenced the solubility of P. Ash and biochar support sorption and immobilization of toxic metals in soils causing either their lower accumulation in biomass or promoting the growth on the extremely contaminated soil. Both applied materials showed their ability to improve soil properties and support plant growth.