unplowed lands covered by natural vegetation. Compared to old plowed lands, the soils of virgin lands contain more humus, nitrogen, and other plant nutrients in the root zone. They also have a better texture and greater compactness. There are fewer weed seeds and a lower level of vital activity by microorganisms. The soils have a distinctive water regime: in arid regions they dry out more, but in moist regions they have a high water content.
There are four primary types of virgin lands in the USSR. Steppe virgin lands have chernozem and chestnut soils. In the European USSR they are almost exclusively in preserves (Aska-niia-Nova in Kherson Oblast and Kamennaia Step’ in Voronezh Oblast). Steppe virgin lands in Soviet Asia (northern, western, and northeastern Kazakhstan, Siberia, and the Trans-Ural region) are almost completely developed.
The virgin lands of the southern steppes and semideserts are confined to the extremely arid regions with light chestnut, brown semidesert, and gray soils (central and southern Kazakhstan, Middle Asia, Azerbaijan). Development of the virgin lands in these regions involves irrigation and special measures to improve salinized soils.
Floodplain virgin lands are widespread in the nonchernozem zone; they are less common in other natural zones. For development, they require drainage and soil cultivation.
The virgin lands of the marshes of the nonchernozem zone of the European USSR, Siberia, the Far East, and Transcaucasia (Colchis) also need preliminary drainage and cultivation.