Brown soils: characteristics and conditions of formation, humus content and natural areas
The distribution of brown soils falls on the climatic zones of the temperate zone with relatively humid and warm conditions. Coniferous, broad-leaved and mixed forests grow in them, under them there is a cover of herbaceous vegetation. Consider the characteristics of brown forest soils, soil formation conditions, profile structure, classification, and species diversity of vegetation. How to improve brown soils for economic use.
Characterization of brown forest soils
Brown forests consist of three horizons. The thickness of the humus horizon, which has a brown color, is 20 cm. It consists of humus and mineral matter. The humus content is high - in percentage 4%, maximum - 8%, the natural fertility of the soil is well expressed.
The composition of humus is dominated by fulvic acids, not humic acids, especially this difference is noticeable in the lower part of the fertile layer. The humus layer is active, soil bacteria and plant roots mix organic matter with mineral particles. Because of this, the boundary between the upper and middle horizons may not be clearly defined.
The second horizon consists of mineral matter washed out of the soil-forming horizon. It also contains organics delivered by microorganisms and worms from the upper layer. The second layer of brown soils is often weakly leached, as a result of which only some s alts pass through the profile. The bottom layer is represented by loams. Looking at the acidity table, brown forest soils have a pH of 5.0 to 6.5.
| Features | Value |
| 20 cm | |
| 4-8 % | |
| Fulvic acids | |
| pH 5.0-6.5. |
Typical forest soils are characterized by the division of fractions of mechanical components along the profile at a uniform level. There is some increase in the amount of silt in the transition layer, which is due to the process of gleying.
Gleying is the process of transformation under the influence of biological and chemical factors of primary minerals into secondary ones, as well as the process of secondary formation of minerals in the process of mineralization from plant residues. During gleying, silt and minerals such as iron, manganese, magnesium, calcium, phosphorus, aluminum and other elements accumulate in the soil layers.
Soil formation conditions and distribution
Geographic location determines the processes that form brown-type forest soils. It is a temperate climate with average temperatures and high humidity (humidity factor greater than 1).
One of the main processes for the formation of brown soils is the gleying of the lower soil horizons, as well as the removal of mobile weathering products. Fertility is due to the presence of permanent organic matter obtained from the fallen leaves of broad-leaved forests and dead herbaceous vegetation.
Burozems are formed on the flat territory, in the foothills, in the valleys, in the mountain-forest regions. They are formed on clay, loam, sandy rock, sand with rubble. In all brown forest subtypes, the inclusion of a large amount of ferruginous minerals was noted.
The annual value of positive temperatures in the regions of brown forest distribution ranges from 2500 to 3000 °C. The amount of precipitation for the annual period is 60-100 cm. The soil freezes, but not deep and not for long. The formation of brown soils is characterized by a leaching water regime.
The natural zone of distribution of brown forest soils in Russia is the Caucasus Mountains, the Altai foothills and the south of the Far East. But they occupy a much larger territory in Central and Western Europe, England, cover the east coast of the United States and East Asia.
Profile structure
The upper layers of the profile are fertile - this is a loose litter, which is made up of tree litter, which is in varying degrees of decomposition, a humus horizon of dark brown color. The layer is loamy, lumpy-granular structure, loose, 20 cm thick. After that comes a transitional layer, gravel-loamy, lumpy structure, 20-30 cm thick. Then there is a yellowish-brown horizon, 30-70 cm thick, compacted, with multiple inclusions of crushed stone, rock fragments. It transitions into weakly weathered eluvium.
Classification
The following types of brown soils are distinguished: acidic, acidic podzolized, containing many acids, slightly unsaturated, slightly saturated podzolized. According to the state of the humus layer, they are divided into coarse-humus, illuvial-humus, gleyic.
Brown forest soils belong to young soils that have formed relatively recently and are still being formed. Therefore, a clear classification of them has not yet been developed.
Agricultural use
Brown forest trees are characterized by rather high natural fertility, so they can be used for growing agricultural plants. Used for sowing cereals, vegetables, vineyards and orchards, for growing conifers.
Mainly used as arable, for hayfields and pastures. Grain and industrial crops are grown in low foothills. These are also areas of developed vegetable growing and fruit growing. In the Far East, forest soils are also actively used for growing various types of crops.
Vegetation
Plants characteristic of the brown forest soil zone are represented by beeches, oaks, hornbeams, ash trees - tree species characteristic of temperate broad-leaved forests. Most of the forests have been cut down, this area is agricultural land.
Coniferous-deciduous forests grow in the Far East. They are dominated by spruces, pines, cedars, fir, hardwoods - lindens, maples and oaks. Highly moistened areas are covered with meadow-marsh and marsh plants.
How to improve the soil?
Despite the high agronomic value of forest soils, when plowing new territories, the humus layer is washed out. To prevent the loss of fertility, it is necessary to carry out reclamation and other agrotechnical measures that will contribute to the preservation of soils: sow green manure vegetation, restore the fertile layer, lime the soil, the acidity of which does not allow growing the main types of crops on it.
Measures for the rational cultivation of crops allow maintaining and even increasing the overall yield, preserving the properties of forest soils within the limits of natural fertility.
Since brown forest soils are usually characterized by the phenomenon of surface waterlogging, measures are required to improve their water-air regime, such as drainage, removal of excess water, improvement of the structure of the plowing layer, increasing its power, and others.
When used on slopes, you need to strengthen them by planting plants with strong roots. With increased moisture, it is necessary to carry out systematic drainage. The use of burozems in agriculture makes it possible to include fresh land in circulation and increase the productivity of the industry.
Proper cultivation of forest lands for arable land and meadow plots, their rational use leads to the preservation and even improvement of the properties of these soils, leaching is suspended, this is due to improved structure, increased bioactivity of microorganisms and under the influence of powerful roots of cereals.
For vegetation, forest brown soils are favorable chemically and biologically, despite the fact that they are not as fertile as black soils. This property is reflected by the lush forests that grow in abundance on them. The annual volume of leaf litter is significant, with approximately 8 tons of leaves falling per hectare. For the biological cycle, a sufficient amount is the mass of organic matter that falls on the ground and forms the forest floor.
For agricultural use, such soils are of interest, both freshly plowed and cultivated. Many important agricultural crops grow and bear fruit on them, and with the use of agrotechnical measures from agricultural fields and orchards, you can get a good harvest.
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