Potassium (K+) is a macronutrient essential for plant growth which is derived from mineralogical sources. Well-established deep rooting profiles govern the nutrient cycling of K+, yet past research has demonstrated that rooting profiles are not reestablished for over eighty years following land use change. This research investigates consequences for K+ cycling dynamics after changes in land use by comparing the effects of the hardwood Acer rubrum on soil exchangeable potassium (EK) and clay mineralogy against the effects of the pine Pinus taeda. Both species had similar effects on EK, but A. rubrum imparted structural changes to the clay minerals which were not observed after the growth of P. taeda. These findings demonstrate that different chemical pathways may be used by various tree species as part of their K+ uptake strategies, contributing to changing nutrient cycling dynamics over periods of changing land use.