Abstract <p>The historical and modern concepts of fallow lands (abandoned croplands), the causes of their occurrence, and some features of their functioning are considered. The main stages of the development of abandoned cropland are highlighted in terms of succession of vegetation in agrophytocenoses arising after the cessation of soil cultivation. The literature data and existing approaches to assessing the land area of arable lands withdrawn from agriculture are analyzed. The prospects of using abandoned fallow lands both in the agricultural sector of agricultural production and on a broader ecosystem scale are considered. It is emphasized that fallow lands of different ages are actually chronological sequences of various dynamic biogeocenoses with highly variable plant and soil components, which make it possible to assess, among other things, the rate of soil formation and degradation processes.</p>