Soil samples from the major horizons of three sandy Michigan spodosols of varying productivity were leached with water extracts of Populus grandidentata Michx. leaves. Laboratory leaching experiments were used to simulate natural weathering of soil minerals by H+ ions of organic acids and the complexing of cations by organic compounds in the extracts. All of the soil samples released significant amounts of Mg, K, Na, and Fe, and most released Ca. Using data for Fe released by the leachings and existing data for Fe accumulation in similar soils, an estimate was made of the number of years of field conditions simulated by the laboratory leaching. The annual elemental release through mineral weathering in the A horizon in each soil was then estimated. Ranges of elemental release from the A horizons, in kg/ha/yr, were: Ca, 0-0.8, Mg, 0.4-0.9, K, 1.3-3.1, Na, 4.0-5.7, and Fe, 1.7-5.8. These results can be used in the evaluation of potential impacts of forest harvest on biogeochemical cycles in similar sites.