The Iron Index has been developed to permit its application to the diagnosis and correction of iron chlorosis in culture growth. The stress in the ratio Fe‐Mn‐Zn enables us to diagnose deficiences with respect to some of these elements in the absence of visual signs. Both Iron Index and ratio Fe‐Mn‐Zn, P/Fe, Ca/Fe, Mn/Fe and Zn/Fe were applied to the nutritional research into several lots of walnuts (Juglans regiaL.) autochthonous from Sierra Nevada, Spain, in the same climatic and edaphologic conditions. These walnuts were sampled from the time their leaves were completely developed to their old age. Leaves were analysed and the mentioned index and equilibriums determined, being possible to verify the metabolic fluctuations and their correspondence with the morphological state in which the plants were every instant. There are no significant differences among each lot. They initially present very high nutritional levels, then they get stabliized, and decline abruptly later on. We deduce that during the autumn‐winter season the trees don't interrupt the absorption of nutrients, since at the beginning of the new cycle they presentveryhigh levels again. The equilibrium period coincides with that of the fruit formation.