Ectomycorrhizal (EM) fungi are known to colonize minerals in forest soil, and in many laboratory experiments it has been confirmed that EM fungi stimulate dissolution of minerals such as apatite, biotite and feldspars. However, due to the low number of experiments performed in the field, and in forests with different soil fertilities, it is difficult to conclude whether this effect has any ecological significance for the overall cycling of nutrients in forest soils. A key question is to what extent EM-induced weathering can compensate for a developing nutrient deficiency situation by increasing dissolution of certain minerals in the soil. We have used ingrowth mesh bags amended with various minerals to study the interaction between EM fungi and minerals. Our results so far indicate that EM fungi were stimulated by the phosphorus (P) containing mineral apatite in a forest with low P status but not in a forest with adequate P. This could be either an effect of an increased allocation of carbon to external mycelium within each fungal taxa or a result of a changed EM community towards species that produce more external mycelium. Furthermore, the EM-induced dissolution of the apatite was more intense in the forests with low P status. We used rare earth elements as marker elements for quantifying transport from the mineral to the ectomycorrhizal roots. In contrast we found no indication that EM mycelia interacted with the potassium (K) containing mineral biotite whether in forests with deficient K or adequate K supply. To confirm these results we suggest that future studies include a larger number of sites and investigate the influence of nutrient status of the trees on EM induced weathering. Such studies will increase our understanding of how forests will respond to a change from nitrogen (N) limitation to limitation by other nutrients such as P or K, a potential consequence of nutrient removal through intensified biomass harvesting and excessive N availability through anthropogenic deposition.