Ash from combusting a mixt. of wood chips, energetic willow, maize, and straw was applied in the 3 y. long exp. in doses 3.5-10.5 Mg/ha as a substitute for K mineral fertilizers to study its effect on soil pH and sorption properties and on contents of plant-available K, P and Mg macroelements. The ash addn. resulted in an increase in the content of assimilable P, K, and Mg forms and in the sorption capacity of the soil.