a lowland in the central European part of the USSR, in Tambov Oblast and partially in Riazan’ and Voronezh oblasts, RSFSR. The Tambov Plain forms the main part of the Oka-Don Plain. It is composed of loess-like loams underlain by Dnieper moraine; still deeper are Neogene sandstone-clayey deposits. The plain is irrigated by the Tsna River and its tributaries (Oka River basin) and by the Don, Voronezh, Bitiug, and other rivers. It has forest-steppe landscapes, with chernozems and gray forest soils. Most of the plain is tilled; wheat, rice, sugar beets, sunflowers, and potatoes are grown.