Gray forest soils: characteristics and conditions of formation, fertility and vegetation

Gray forest soils are soils that form in the south of the forest zone and in the forest-steppe. In the European part of Russia, their formation occurs under broad-leaved forests, and in Siberia - under small-leaved forests. These types of soils are formed on clayey and loamy deposits of various origins - mostly loess-like. Also, these lands are localized in the southern mountain systems.

Features and location

Gray forest soils are located in the forest-steppe under conditions of periodically flushing water regime, under broad-leaved mixed or small-leaved forests with abundant herbaceous vegetation.

Such soils are common in the temperate zone. The parent rocks in Russia are presented in the form of loess. There are also loess-like and cover loamy soils. Moraine deposits are sometimes observed in this natural zone.

The relief is wavy. In the European part it is strongly dissected by water erosion, in Western Siberia it is flat, and in Eastern Siberia it is gently ridged or hilly.

Geographic location determines the properties of such lands. Most of this type of soil is found in the northern hemisphere. They are located in places with a temperate climate. Gray forest soils have become widespread in Canada, the USA, Russia and other countries.

Characteristic

Gray forest soils are characterized by special properties. They differ in profile structure and soil formation conditions.

Profile structure

Gray soils have a fairly complex morphological structure and high fertility. Level A0 represents the forest floor. Its formation is associated with the presence of woody deciduous matter and the mass that remains from herbaceous plants. The thickness of this layer does not exceed 20-40 millimeters.

After it is a humus-accumulative horizon. It has a gray color. In this case, the saturation of the layer may differ. It is characterized by a lumpy-nutty structure. Power parameters reach 150-200 millimeters.

In the deeper layers there is a humus-eluvial layer, which is also called podzolized. It has a white color, which is caused by silica powder. Such a horizon takes 100-150 millimeters.

For the next level - A2B, a dark color and an acute-angled-small walnut structure are characteristic. Sometimes this layer is missing. The boundaries of the structural layers are dark gray or black and white.

Then the following layers are observed:

1. Illuvial level B - has a brownish-brown color and includes streaks of humus components. It is characterized by a nutty-prismatic structure.
2. Transition layer.
3. Parent rock - has a yellowish tinge and includes carbonates.

Soil formation conditions

Such soils are located in the south of the forest zone and in the forest-steppe. The main condition for their appearance is the powerful development of herbaceous vegetation. It is mainly localized in deciduous forests.

These soils are characterized by large amounts of useful elements and low acidity parameters. The decomposition of wood litter is caused by fungi and bacteria. As a result of these processes, a lot of humic acids are produced, and the humus content increases. It ranges from 3 to 8%. At the same time, the thickness of the humus horizon reaches 25-30 centimeters.

Climate and vegetation

Gray forest soils form in temperate continental climates. It is characterized by the absence of heavy precipitation. An increase in the number of sunny days and light forests provoke a decrease in the process of soil podzolization, as well as accelerate and stimulate the process of turf formation.

The process of soil formation is influenced by the average daily temperature parameters in July and January. In July they are 19.5-20 degrees in the west and 17.5-18.5 degrees in the east. The growing continentality of the climate leads to significant differences in January temperatures.They can range from -4 to -25 degrees.

Linden, oak, maple, and other types of trees are considered the basis of broad-leaved forests. They consume a lot of magnesium, calcium and silica.

Types of gray forest soils

Such soils are considered one of the most fertile. However, they have several varieties.

Light forest gray

This group of soils is characterized by low podzolization and limited thickness of the humus layer. This subtype is distinguished by the presence of the A2 horizon. The surface litter mainly consists of brown foliage, which rots little. The structure also includes branches and other fragments of plant litter. Below is a mass resembling felt. In it, the vegetation, which is partially rotted, mixes with the ground.

Next are the following horizons:

• humus-accumulative - is 150-250 millimeters, less often it reaches 350;
• intermediate - its size is 120-200 millimeters;
• illuvial.

Intermediate horizon can be podzolized. It can also be humus-podzolized. This layer has a lighter color compared to the surface earth. This layer is characterized by a large amount of silica powder. The transitions between the illuvial and intermediate horizons cannot be called clear. At a depth of about 2 meters, carbonates are present.

Grey Forest

These types of soil are characterized by weaker podzolic processes compared to light masses. The content of the clay fraction at different vertical levels differs by at least 20%. The depth of carbonate deposits is 1200-1400 millimeters.

The rest of the indicators include the following:

• different mechanical condition - the spread is from sandy loam to loam;
• fulvic acid variety of humus;
• bulk density in arable structure - 1.32-1.4 grams per 1 cubic centimeter.

Dark forest gray

This type of soil is characterized by an uneven location in the forest-steppe. It is predominantly concentrated in the low slopes of river floodplains. Colloids almost do not move along the soil profile. The soil is characterized by a pronounced structure. But it is easily washed out under the influence of water. The dark gray soil contains many mobile nutrients.

Other characteristics include the following:

• weight of arable structure - 1.2-1.42 grams per 1 cubic centimeter;
• part of humus in plowed places - 4.9%, on virgin lands it can reach 10%;
• presence of grounds - 80-95%.

Economic use

Such soils are actively used in agriculture. They are suitable for growing cereals, corn, potatoes, beets and other crops. Dark gray soils are considered the most fertile. In gray and light gray types of soil, it is required to introduce organic matter and mineral supplements, deepen the arable layer, and perform liming.

Gray forest soils are considered very fertile. They contain quite a lot of humus and are actively used in agriculture. However, sometimes it is necessary to apply additional nutrients to increase yields.

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