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Mountain pastures can be improved by the application of wood ash, but its effectiveness as a source of N, P and other elements requires improved management practices. Two application rates of wood ash (6 and 12 t ha-1) were tested in a 4-year trial on a low-input fertilized pasture. Ash was complemented with mineral P, and N fixation was encouraged by sowing white clover. Wood-ash application led to increased pasture yield (by 100%) and to increased proportions of white clover and ryegrass (60%), thus improving pasture feed value. N fixation by white clover, and possibly increased mineralization because of higher pH, may have compensated for lack of N in the wood ash. Addition of mineral fertilizer improved the supply of P, although incorporation of the wood ash into the soil may also have enhanced release of P from non-extractable components. High amounts of compounds containing Ca and Mg contributed to the long-term maintenance of soil reserves of these elements. Despite high inputs of K (175–350 mg kg-1) from wood ash, annual additions of K are required to counteract depletion via plant uptake and leaching. Increased Mn availability after the treatment (up to 400 mg kg-1) may limit repeated applications of wood ash, at least on poorly aerated soils.