Taking advantage of the long term field stationary experiments in Skierniewice started at 1922 based on fixed mono-fertilization, the mobility of the exchangeable cations Ca, Mg, K, Na was studied for the whole soil profile up at a depth of 100 cm. Mobility was studied using an electrodialysis method to remove and determine cations in the cathode solutions. Calcium proved to be most mobile element and sodium the least mobile and the mobility ranking of exchangeable cations in the soil under investigation is as: Ca > K > Mg > Na. The genetic horizons of the soils showed differentiated mobility for individual cations. Cations in the surface horizons (up to 50 cm) are more mobile than in the deeper horizons with trace amounts of humus.