The article considers the change in the properties of Haplic Chernozems (Aric) on loesslike loams and Сalcaric Phaeozems (Aric) on Paleogene, Neogene red-colored sands with limestone eluvium of the Lipetsk region when they are transferred from cropland to fallow. The main attention is focused on the change in the carbonate status of soils. According to the results of the study, it was found that the transformation of both types of soils formed on different rocks obeys a single trend. Carbonates in Chernozems during their stay in fallow are washed down the profile; stable forms of carbonate pedofeatures gradually disappear. The content and stocks of carbonate carbon in the 0-200 cm layer in Haplic Chernozems (Aric) decrease by 27.5 t/ha by 25 years of fallow state. In Сalcaric Phaeozems (Aric), changes in the carbonate status are less pronounced; nevertheless, it was found that in the arable soil on the fragments of limestone, secondary carbonate films in the form of acicular calcite are formed on top of clay films, which was not observed in the abandoned soils. When the soil is in the fallow, the physical and mechanical properties of the soil improve: the structure of the arable horizons is improved, density decreases. The organic carbon content is reduced. This is an atypical result of postagrogenic transformation of Haplic Chernozems (Aric). In the fallow soils of other regions of steppe and forest-steppe, we observed the process of accumulation of organic carbon. The decrease in soil organic carbon while in the fallow is associated with the use of soil-saving technologies for agricultural use. The radiocarbon age of humus in subsurface horizons increases when soil is in the fallow. The radiocarbon age of carbonates in soils varies depending on the amount of lithogenic calcite inclusion.