Gray Forest Soil

a type of soil that forms primarily in a continental, moderately humid climate in forests (usually hardwood) with grassy vegetation. Gray forest soils form on loesslike cover loams, carbonate moraines, and other parent materials that are usually rich in calcium and have an elutriate water regime. All gray forest soils are podzolized to some extent, but the process of podzol formation is weaker than in podzol soils owing to the parent material’s low water permeability and saturation with calcium. The movement of humates of potassium from the top horizons to deeper ones and precipitation on the surface of structural partings in the form of humus films are especially typical of gray forest soils.

The following horizons are identified: A₀—forest litter (only in forest soils); A₁—gray humus horizon measuring 12–30 cm thick (humus content of 2–8 percent); A₂—gray podzolized horizon with plated structure; A₂B—dark gray transitional horizon measuring 12–30 cm thick and having a lumpy or coarse grainy texture (humus films on structural partings); B—eluvial horizon; and C—parent material.

Gray forest soils are mostly acidic, especially in the A₂B horizons and the upper part of the B horizon; alkaline or neutral soils are typical of the lower part of the B horizon. Gray forest soils have relatively good physical properties and are biologically active and fertile. They are divided into the following subtypes: light gray (similar to soddy podzols), gray, and dark gray (resembling leached chernozems).

Gray forest soils are found primarily in the USSR, in the northern part of the forest steppe, where they form a discontinuous band from the Carpathians to Transbaikalia. They are also found in Canada and adjacent regions of the United States. The soils are used for the cultivation of grains, industrial crops, vegetables, and fruits.