Gray forest soils: characterization, formation conditions, properties

In the green massifs, where the forests are of deciduous breeds, the formation of gray forest soils. Natural area of their location - the area of moderate continental climate. These are areas where there is an increased number of days of sunshine and no rainfall.

Distribution

Gray forest soils are located in the vast territories of Russia. The vast territory they occupy in Canada and the United States. This forest-steppe zone bordering in the North to taiga areas and in the South-steppe region.

Gray forest soils in the territory of Russia, constitute continuous strip of the European part of the country. They meet in a broad zone from the Ukrainian border to the Ural mountains. Capture of gray forest soil and the area situated somewhat to the East, to the Altai. This area of the West Siberian lowland. The gray area of the soil - this is 3.5% of the total area of the Russian Federation. Below we will consider what are gray forest soils. Characterization in Russia these lands and their primary use in agriculture will also be highlighted in this article.

Topography

In General, the character of the landscape territory of finding the grey soil is flat. In the European part of the forest-steppe plain is rolling and wavy. In Asia, furthermore, even with flat areas. In the forest there is a whole network of ravines and gorges. This relief also affects the characterization of grey soils, as it induces natural drainage of the territory.

Formation

How are gray forest soils? The conditions of education for them is optimal only under a continental climate. This is the average annual air temperature plus seven degrees in the West to minus four and a half to the East. Also on the shaping of the land affects a certain amount of shortfall during the year precipitation. In the territories West of the Ural mountains it is about 500-600 mm, and to the East of these ridges – 300 mm there is an equal balance of precipitation and evaporation. In all areas, which formed a gray forest soils, observed the same average July temperature. They are 19-20 degrees.

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Gray forest soils formed under vegetation represented by herbaceous deciduous forests. West of the Dnieper they have oak-hornbeam composition. To the East, to the Urals, in the forests grow limes and oaks. Sometimes found ash. East of the Ural ridges are dominated by aspen and birch forests. Further, the TRANS-Baikal region, there is a larch.

Due to the high weight of the litter of deciduous trees have certain properties of gray forest soils. Their composition indicates a high content of ash elements and calcium. All these substances enter the soil with litter, the weight of which, according to scientists, is from 70 to 90 quintals per hectare.

On the territory of forest-steppe there are soil-forming rocks are represented by loam. This carbonate deposits.

In terms of herbaceous broadleaf forests in the world there are two main processes. Without them there would be able to form a gray forest soil. Feature-forming layer is directly connected with these processes. The first of these occurs under the influence of a downward current of water from falling on the earth atmospheric precipitation. The result of this process is to make products of soil formation and weathering in the lower horizons of the rocks. Sometimes these substances in the layers of loam.

The Second, equally important process, due to the fact that the gray forest soil formed under deciduous trees and herbs. Dead vegetation, rich in minerals, deposited in the upper horizon in the form of organic residues. At the same time in the surface layers of the soil humus is formed. This layer is rich in organic minerals associated with calcium. To a small extent in the forest goes pozhalovalsya process. It enriches the upper layers of soil sesquioxides oxides and oxides of magnesium, calcium and many other elements.

Structure

Gray forest soil (photo below) represented by five layers.

The upper one has a thickness of 3 cm litter, consisting of naberegnaja dead grass and mortality. Next is the more powerful granular gray layer, whose thickness is 12 cm and It is formed from humus and has a loose structure. The depth of the third layer of 12 cm and the soil is painted in walnut or light grey. In this layer there are inclusions of silica and humus. Further, the soil acquires a brownish tinge. In this layer, where the accumulated organic ferrous compounds, often glossy blotches. Following is the source rock yellow-brown color.

The type of the gray soil there are the following subtypes:

• Light gray
• Gray;
• Dark gray.

This classification depends on the nature flowing in the earth's processes podsalivaya.

Chemical characteristics of grey soil

The Composition and quantity of micro and macroelements, depends on the conditions of formation of all layers of the horizon. Whatchemical properties are gray forest soils? The characteristics obtained in the study of their aqueous solution, allows to speak about present slightly acid and acid reaction. In addition, the results of laboratory analysis show low saturation of such soils by bases and reduced in the first two horizons of silty particles.

A chemical study can clearly identify which subtype are certain gray forest soils. Characteristics of them are different. So, dark-grey forest soils are distinguished by a large amount of accumulated humus. They found a predominance of humic acids over fulfokisloty. What differentiates dark gray forest soil? The characteristic given as the result of chemical analysis confirms the accumulation of calcium. This item is located in the upper horizon.

Characteristics of grey forest soil, obtained as a result of chemical studies, indicates the poverty of its upper horizons of poltorackiy and significant enrichment with silicic acid. This composition confirms the process of podsolennom. This is most clearly expressed in the light grey subtype of soils. Less dark gray. Depending on the subtype of soils have different chemical properties. For example, light gray have an acid reaction. However, they do not differ in the saturation of the base.

Characteristics of grey forest soil indicates that this subtype also has the acid reaction. While there is some unsaturation bases. However, this appears less than the light grey subtype.

The Third type of soil has the most favorable chemical properties. Dark gray soils have a weak acid reaction and greater base saturation. In addition, they have a high content of humus, phosphorus, calcium and nitrogen.

Plays an Important role for those who study the gray forest soil characteristics.

A table that lists all the properties of the various subtypes, allowing it to better memorize all the data obtained by researchers.

Physical characteristics

Properties land plots of forest-steppe zone is largely dependent on the content of humus. On the physical properties of grey soils influences the mechanical composition of the initial parent rocks.

The Upper layers of these areas are of high porosity, up to 60%. As you move down the profile density of the soil increases. This is due to the decrease in the concentration of humus. The data of physical properties are some differences depending on the subtype of the examined soil. So, in the dark gray rocks of the density even lower horizons of the small. It is quasirandomly and more pronounced structure.

One of the physical characteristics is the density of the illuvial horizons. All subtypes of the grey soil, it is quite high. Its value ranges from 1.5 to 1.65 grams per cubic centimeter. As for the total porosity, it is in the range from 50 to 60%. And in the upper horizons – 40 to 45%. Characterization of porosity in light grey subtype is inclined to the capillary type. This feature leads to a decrease in soil permeability.

As for the dark grey of the subtype, then its physical properties are most favorable. This soil features a large water capacity that allows the whole plant to obtain much-needed water. Gray and light gray subtypes of land of forest-steppe zone, they have little favourable physical characteristics. This low content of humus, and a small percentage of silt, and the large number of silty fractions. All these qualities contribute to obstructioni the upper layers of the horizon after their plowing. Such land swim quickly, and on their surface, the formation of crusts.

The Microstructure of the different subtypes of grey soils different from each other and vodorodnoi. For example, light-grey appearance after plowing quickly compacted. This is due to the fact that this subtype of soil is observed the presence of water stable aggregates larger than 0.25 mm.

Biological features

Humus grey soil accumulates in the upper horizons and is a whole group of high molecular weight congeners. This biological component-the main organic material of the first layer of the profile. It has a lot of phosphorus, nitrogen and other elements. The formation of humus comes from deciduous and vegetable dips, as well as from dead plant roots, with the active participation of microorganisms.

Heat treatment

According to this indicator, grey forest soil properties are quite favorable. For a long period, lasting from April to December, around the their profile there is a positive temperature. Freezing comes with the onset of winter, and sometimes in January. By April, the layer depth from 50 to 70 cm is entirely thawed.

In the Central and Western zone of forest-steppe soils are attributed to the facies subtype of heat provision. Here you can watch the periodic freezing and thawing of the upper layer throughout the winter period.

A Different thermal regime of soils typical of Western Siberia. Here is a longthe freezing of the layers of horizon. In addition, with the onset of spring soil thaw slowly. This is due to severe frosts and low snow cover. Field work in these areas are beginning to hold in may. However, at this time at the lower level still has a negative temperature.

Air

This feature is a collection of a large number of phenomena. All related to entering the soil air, its further movement along it, as well as consumption. This same attribute and the phenomenon of gas exchange that takes place between the layers of the horizon and the surrounding atmosphere.

The Soil air with the arrival of the next season is undergoing some changes of its composition. And in the upper layers this process is much more intense.

Water treatment

Gray forest soils characteristic of periodically flushing type of the indicator. Usually falling in the autumn heavy rainfall moistened the earth, only 50 see More deep moisture penetrates at the time of spring thaw. In this regard, the thickness of the drenching of the soil depends on the capacity of winter cover and runoff of meltwater.

Certain characteristics of the water regime observed in the areas with rugged terrain. Here, the maximum flow rate of moisture in summer can be 20% to cover the soil layer with the thickness meter.

A Completely different water regime of the soil located in forest. Here in winter there is a big accumulation of snow. In this regard, in the spring the soil is moistened much more intense. Subsequently, however, it uses the deep root system of trees. It drains the soil to a depth of 4 to 5 meters.

Nutritious

The Most favorable properties for this measure have dark-gray forest soils. They have high natural fertility due to the large volume of their humus, phosphorus and nitrogen.

The Nutrient status of the soil depends on its culturenet and fertilizer use. In such cases, the upper layers of the horizon will contain a greater amount of nutrients.

On the nutrient status of soils is affected by the content of hydrolysis nitrogen. Especially poor in this element of light-gray soil. One of the indicators of the fertility of land is the presence of mobile phosphorus. The maximum number of this item is in residual-carbonate soils.

The Summer helps to activate chemical, biological and other processes that occur in arable soils. In the middle of the warm season occurs increase of hydrolytic and exchange acidity. In this regard, reduced saturation of soil bases.

Economic activity

In the agricultural sector of the country widely applied area in which there are gray forest soils. The fertility of the land allows people to successfully grow various crops. In addition, gray forest soils occupy its place in the structure of pastures and pastures as well as hayfields.

The undeveloped, agricultural forest-steppe zones are grown winter and spring wheat, corn and sugar beets, flax, potatoes, etc. In the European part of the steppes, widespread gardening.

In the economic turnover included all subtypes of gray soils. This person strives to improve their fertility, using a whole range of activities. A powerful fertile topsoil is created using fertilizer and grass cultivation. It improves the physical characteristics and nutrition of the soil, and reduces the ability to form crust on the surface layer. Moreover, land with high acidity to improve their performance subjected to liming.

The Process of domestication of the forest gray, and light gray soils is possible in the deepening of the plow layer. This event is accompanied by application of fertilizers. If necessary, carry out liming land.

The Fertility of dark-grey soils increases the systematic application of fertilizers. And to eliminate their increased hydrolytic acidity of the used phosphate fertilizer.

The Agricultural use of the gray soils should be accompanied by anti-erosion measures. This is especially true of the European territory of the steppe zone. For adoption such measures treat the soil across the slope, arrange the earthen ridges, etc.