Ammonium nitrate fertilizer, whether applied in spring, summer or autumn, resulted in a rapid increase in the total N content of most tree tissues, although autumn‐applied N remained mainly in the tree roots through the winter. The total P content of the trees was increased by added N fertilizer but the total K content was decreased. Analysis showed that significantly more N was lost in the leaves abscissing from the spring and summer‐N trees than from the autumn‐N trees or controls; also more P was lost from trees given spring N.