‘Katja’ apple trees on M.9 Emla, M.9 751, M.9 984 and P 60 were planted on a silty loam alluvial soil, strongly fixing K, in autumn 1992. They were grown on non-irrigated and irrigated plots, with different potassium fertilisation applied since 1980. Leaf samples were taken in the years 1999–2001. Irrigation had not any significant effect on leaf mineral element content. However, a tendency to increasing leaf K concentration and decreasing Mg concentration in irrigated trees was noted. Fertilisation, irrespective of the dose and mode of application, significantly affected leaf mineral status. The annual doses of 200 kg K₂O·ha^-1 and cumulative dose of 800 kg K₂O·ha^-1, applied once in every four years, significantly increased K and P concentration. Leaves of non-fertilised trees contained more Mg. Leaves of P 60 contained more Ca and less Mg.

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