Chestnut soils are called soils, the condition for the formation of which are dry steppes. What properties chestnut soils have, how they were formed, where they are distributed, read in this article.
Where and how are chestnut soils formed?
The place of origin is dry steppes with an arid climate, insufficient rainfall, high levels of evaporation. Chestnut soils are formed under sparse vegetation, so the soddy process is poorly developed here in comparison with the chernozem zone. Moisture conditions determine how weakly or strongly the sod process will be expressed.
Its more intense manifestation is characteristic of the northern regions of the zone, where the formation of the richest humus soils - dark chestnut soils - is taking place. With the advancement to the south, the dryness of the climate increases. There is a transition of these soils to chestnut, and then to light chestnut, in which the humus content is low, the thickness of the horizon is small.
If there is little precipitation and the soil is poorly washed, the s alt products of soil formation cannot penetrate deep, so they remain on the surface. With intense decompositionvegetation, along with such compounds as calcium, silicon, magnesium, alkali metals are also released in large quantities. Due to their presence in the soil, solonetsity begins to develop. An important feature of soil formation in the steppe zone with a dry climate is that the solonetzic process is superimposed on the soddy one.
Soil types of dry steppes
- Southern and ordinary chernozems.
- Dark chestnut.
- Chestnut.
- Light chestnut.
Chernozems and chestnut soils stretch from the west to the Altai foothills in a continuous strip. To the east of Altai there are small isolated islands in the region of basins, in the Selenga and East Transbaikal steppes. These soils are widespread in the Caspian lowland and Kazakhstan, in the area of the small hills.
For comparison: chernozems occupy 8.5 percent of the territory of the Russian steppes, and chestnut soils - only 3. The main feature of chernozems is a high content of humus. Typical chernozems are characterized by deep groundwater. It is noteworthy that the upper layer of the soil is well wetted by precipitation, the lower one - by groundwater, and a dry horizon is located between them. It is these conditions that are suitable for the formation of chernozem and chestnut soils.
In each subtype of chestnut soils, depending on thermal conditions, the following groups are distinguished: warm, moderate, deep-cold. In addition, within a separate subtype, the soil is divided into genera. This iscommon, solonetzic, solonetzic-saline, residual solonetzic, carbonate, carbonate-saline. It should be noted that chestnut soils of different genera have an unequal manifestation of signs of both solonetzic and solonchakousness.
Dark chestnut soils
They occupy the northern part of the zone. Dark chestnut soils are characterized by a cloddy or cloddy-granular structure of the humus horizon on virgin lands, and silty-cloddy on arable lands. The occurrence of gypsum and easily soluble s alts occurs at a depth of about two meters. Characterization of chestnut soil is impossible without a description of the thickness of the humus horizon. In this soil, it reaches 50 centimeters. In solonetsous soils, the humus horizon is denser in the lower part. This is due to the fact that colloidal particles enrich it.
Dark chestnut soils have a lumpy and lumpy structure. Their properties are more pronounced with an increase in the solonetzization of the horizon. Structural edges have a brownish-brown lacquered crust. The genus of solonetzic dark chestnut soils is subdivided into the following types:
- Non-saline. They absorb up to 3 percent of sodium from the total absorption.
- Slightly saline soils - 3-5 percent.
- Medium saline – 5-10.
- Strongly solonetzic – 10-15.
Characteristics of dark chestnut soils
- Alkaline-saline soils of dark color are highly saline rocks. At a depth of one meter, the content of water-soluble s altsincreasing.
- In residual alkaline soils, the content of exchangeable sodium is imperceptible. Here, solonetzization is of a residual nature.
- In alkaline-s alty soils, the upper or lower part of the humus horizon has signs of solodization, which are represented by silica powder on the structural faces.
- Carbonate chestnut soils have high carbonate content on the surface. The place of their formation are heavy rocks.
- The formation of carbonate-alkaline soils occurs on saline rocks with a heavy mechanical composition. The soils have a high density and a fissured profile. When they are wet, they begin to swell and become very sticky.
Characteristics of chestnut soil
It is distinguished by the thickness of the humus horizon. In chestnut soils, this figure is 30-40 centimeters. Most carbonates accumulate at a depth of 50 centimeters, gypsum - 170, and water-soluble s alts - at a depth of two meters. These soils have the same generic characteristics as described above.
Light chestnut soils
The zone of their formation is the southern part of the dry steppes, occupied by wormwood and cereal plants. These soils form in a highly arid climate. The thickness of the humus horizon is small - 25-30 centimeters. It has a structureless composition and weak washing. Because of this, the carbonate layer lies close to the surface. The depth of the gypsum horizon is 1 meter 20 centimeters. In this soilEasily soluble s alts accumulate in large quantities, so the signs of solonetsity appear everywhere. Non-alkaline chestnut soils are extremely rare.
The upper horizon of this soil has a lighter color, its structure is loose. S alting influences this. Light chestnut soils are divided into genera in the same way as others. Alkaline and alkaline soils in light soil are more pronounced and have a zonal character.
Use
The soil of the steppes, especially dark chestnut, has sufficient reserves of nutrients. She has a high fertility. It grows wheat, millet, corn, sunflower, melons and horticultural crops. Productivity is greatly increased if phosphorus, potash, nitrogen fertilizers are introduced into the soil and moisture is retained in it.
Chestnut soil without dark or light shades is more often used for hayfields, pastures, arable lands. But it is also suitable for growing the above crops. On light chestnut soils, various crops can be grown only with regular irrigation.
Alkaline chestnut soils are distinguished by unenviable fertility. Therefore, to increase it, chemical and biological reclamation is used. Sometimes deep plowing is enough.
Flaws
- Light chestnut, chestnut and alkaline soils of the steppes have a humus layer of small thickness. This cannot provide normal conditions for the root layer.
- The compacted horizon is relatively shallow. This disrupts the water regime of the soil and prevents plant roots from penetrating deep.
- Alkaline soils have an increased concentration of alkali, which makes it necessary to acidify the soil before using it.
- Steppe soils lack moisture and nutrients, especially light chestnut soils.
Man must help chestnut, thin, low structure and alkaline soils become strong, rich in humus and nutrients. It is necessary to systematically irrigate the soil to replenish its water supply, apply organic and mineral fertilizers to it, and follow the latest agricultural practices.
