Soddy Calcareous Soils

(rendzina), soils formed on carbonate rocks (limestone, chalk, dolomite) beneath coniferous, deciduous-coniferous, or broad-leaved forests. Such soils are water permeable. A typical soddy calcareous soil consists of a humus layer 10-15 to 30-40 cm thick and the carbonate rock underlying it; it is dark gray and effervesces because of acid from the surface. Typical properties of soddy calcareous soils are a weak alkaline or close to neutral reaction in the humus layer and a weak alkaline reaction in layers B and C; a high humus content (6-15 percent); complete saturation of the absorbing complex with bases (Ca and Mg); in the cross section, a lack of differentiation in mechanical composition; a water-resistant granular or nutlike-granular structure; high biological and microbiological activity; and significant reserves of nutrients (phosphorus, potassium, and nitrogen). Three types of soddy calcareous soils may be distinguished: typical, leached, and podzolized. On the basis of humus content the following types may be identified: humus (more than 12 percent), high-humus (5-12 percent), medium-humus (3-5 percent), and low-humus (less than 3 percent). In terms of the depth of the humus layer they are classified as shallow (less than 15 cm) and medium-depth (more than 15 cm) soils. Soddy calcareous soils are divided into varieties according to mechanical composition (clayey, loamy, and sandy) and degree of stoniness (high, medium, and low). In the USSR soddy calcareous soils are common in the taiga and forest-steppe zones of the European USSR and of Siberia. The largest concentrations of soddy calcareous soil are found in the Baltic region and in Leningrad, Pskov, Novgorod, Vologda, Perm’, and Kirov oblasts.