Ecological-hydrological and genetic features of the soils of the Tambov Plain

Specific features of the genesis of chernozem-like, solonetzic chernozem-like soils, and hydromorphic chernozem-like solonetzes were investigated on the southern Tambov Plain. Typical chernozems occupy well drained areas. The yield of cereals is limited by the amount of precipitation. On the flat surface of weakly drained watersheds, deeply gleyed chernozem-like soils are formed under the influence of bicarbonate-calcium ground water and water stagnation on the plow sole. In closed depressions with the 1.5- to 2.0-month long stagnation of surface water on the compact lower horizons, podzolized gleyic chernozem-like soils are formed. They have favorable physical properties, weak eluvial differentiation, and rather high acidity. In humid and moderately humid years, the cereals on these soils are waterlogged; in dry years, their yield increases by 20% as compared to that on the typical chernozem. In the low undrained areas of the watersheds, solonetzic chernozem-like soils and hydromorphic chernozem-like solonetzes are formed under the influence of bicarbonate-sodium water. Despite the unfavorable physical properties of the solonetzic horizons, their better supply with moisture determines the possibility to obtain stable high yields of cereals on the solonetzic chernozem-like soils. The productivity of the gleyic chernozem-like solonetzes is low irrespective of the humidity of the year.