High sorption capacities of soils in respect to potassium enable the application of the latter in high doses to meet the nutritional requirements of all plants in crop rotation. However, overstepping a certain level and braking off buffering capacity of soil may appear unfavorable for both the plants and soil environment. Tests were performed on brown soil in profiles reconstructed in plastic tubes 7 cm in diameter and one meter high. Potassium (in KCl form) was introduced down to the level of ploughed humus of the soils in the equivalent quantities of: 0, 25, 50, 75, 100, 125, and 150% of sorption capacities at A_p level and water was poured to simulate 420 mm of precipitation. The applied doses of potassium had an unequal effect on the dynamics of chemical processes. Potassium in high doses strongly extracted magnesium and calcium cations from the surface layers to deeper levels and to the filtrates. It had no effect on hydrogen desorption or on the dynamics of bioavailable forms of phosphorus. The elements Mg>Ca>Na>K, in this order, were most washed out of the profile, whereas K>Mg>Na>Ca, in this order, exhibited the highest dynamics under the effect of fertilization.