The method of utilization of biomass ash in agriculture as an agrochemical is considered. Studies have shown that biomass ash contains a number of macro- and microelements essential for agriculture, such as phosphorus, potassium, calcium, magnesium and sulphur. Based on the content of the main chemical components and physical and chemical parameters of wood and plant ash, conclusions are drawn regarding its use. Wood ash with a high calcium content is suitable for agromelioration of soils with a low pH value. Ash from agricultural crop straw with a high calcium and potassium content is suitable for the production of potash fertilizers, and with a high potassium and phosphorus content - for the production of phosphorus-potassium fertilizers.