The aim of this work was to ascertain the levels of some selected chemical and physico-chemical properties in the fallow soils and in the neighbouring fields under cultivation. The studied fields were located on heavy brown fen soil, uncultivated for 4 and 8 years and rusty soil that lay tallow tor 8 years. Fallow soils, in comparison to arable soils, were characterized by a lower content of organic carbon and available potassium forms as well as phosphorus and magnesium. Changes in the properties of arable soils under cultivation and the soils allowed to lie fallow were much clearer in the clay soils (heavy fen soil) than in sandy rusty soils. Humus horizon in the 8-year tallow clay soil was characterized by an increased hydrolytic acidity and decreased exchangeable calcium level in the sorption complex.