Biomass ash and biochar emerge from the present analysis as promising and sustainable soil amendments that can partially substitute for conventional mineral fertilizers. Biomass ash, generated as a residue from the combustion of woody and herbaceous biomass, contains significant amounts of macronutrients such as calcium, potassium, phosphorus, and magnesium. Its alkaline nature enables effective neutralization of acidic soils. For this reason, biomass ash is often considered functionally comparable to liming agents. In nutrient-poor soils, it provides essential elements that are readily available to plants. Biochar, by contrast, is produced through the pyrolysis of biomass under limited oxygen conditions. It is characterized by a high proportion of stable organic carbon that resists biological degradation, making it an efficient long-term carbon sink in soils, potentially lasting hundreds or even thousands of years. Its porous structure and large surface area enhance the soil’s cation exchange capacity and water retention potential, thereby improving fertility and reducing nutrient losses from the soil profile.