Chestnuts are called such soils, the condition for the formation of which are dry steppes. What properties chestnut soils have, how they 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, and a high level of evaporation. Chestnut soils are formed under sparse vegetation, therefore, the turf process here is poorly developed in comparison with the chernozem zone. From the conditions of moistening depends on how weakly or strongly the turf process will be expressed.
The northern regions of the zone, where the formation of the most humus-rich soils — dark chestnut — are characterized by its more intense manifestation. As you move south, dry climate increases. There is a transition of these soils to chestnut, and then to light chestnut, in which the humus content is low, the horizon thickness is small.
If there is little rainfall and the soil is poorly washed, there is no way to penetrate the salt products of soil formation deeply, so they remain on the surface. With intensive decomposition of vegetation, along with compounds such as calcium, silicon, magnesium, alkali metals are also released in large quantities. Because of their presence in the soil, alkalinity begins to develop. An important feature of soil formation in the steppe zone with a dry climate is that the brackish process is superimposed on the turf.
Types of dry steppe soil
- Southern and common chernozems.
- Dark chestnut.
- Chestnut.
- Light chestnut.
Black soil and chestnut soil in a continuous strip stretched from the west to the Altai foothills. To the east of Altai there are small separate islands in the basin region, in the Selenga and East Transbaikal steppes. These soils are widespread in the Caspian lowland and Kazakhstan, in the region of the small hills.
For comparison: chernozems occupy 8.5 percent of the territory of Russian steppes, and chestnut soils - only 3. The main feature of chernozems is the high humus content. Typical chernozems are distinguished by a deep occurrence of groundwater. It is noteworthy that the upper layer of soil is well soaked by precipitation, the lower - by groundwater, and between them there is a dry horizon. 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 single subtype, the soil is divided by genera. It is ordinary, solonetzic, solonetzic-solonchak, residual-solonetzic, carbonate, carbonate-solonetzic. It should be noted that chestnut soils of different genera have an unequal manifestation of signs of both solonetzic and saline.
Dark chestnut soil
They are occupied by the northern part of the zone. Dark chestnut soils are characterized by a lumpy or lumpy-granular structure of the humus horizon on virgin lands, and on arable ones - by a dusty-lumpy one. Gypsum and readily soluble salts occur at a depth of about two meters. A characteristic of chestnut soil is impossible without a description of the thickness of the humus horizon. At this soil it reaches 50 centimeters. In solonetzic soils, the humus horizon in the lower part is denser. This is because colloidal particles enrich it.
Dark chestnut soils have a lumpy and clumpy structure. Their properties are more pronounced with increasing salinity of the horizon. The structural faces have a brownish-brown lacquered crust. The genus of solonetzic dark chestnut soils is divided into the following types:
- Non-saline. They absorb up to 3 percent of the total absorption.
- Weakly saline soils - 3-5 percent.
- Medium-solonetzic - 5-10.
- Strongly saline - 10-15.
Characterization of dark chestnut soils
- Brackish-solonchak dark-colored soils are highly saline rocks. At a depth of one meter, the content of water soluble salts increases.
- In residual solonetzic soils, the content of metabolic sodium is imperceptible. Here, the salinity is residual.
- Upper or lower part of the humus horizon in solonetz-solodized soils has signs of malting, which are represented by siliceous powder on the structural faces.
- Carbonate chestnut soils have a high carbonate content on the surface. The place of their formation is heavy breed.
- The formation of carbonate-solonetzic soils occurs on saline rocks with a heavy mechanical composition. Soils have a high density and fractured profile. When they are wet, they begin to swell and stick strongly.
Chestnut soil characterization
It is distinguished by the power 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 salts - 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 are formed in a very arid climate. The thickness of the humus horizon is small - 25-30 centimeters. It is characterized by 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 soil, readily soluble salts accumulate in large quantities, so signs of solonetzism are manifested everywhere. Not saline chestnut soils can be met extremely rarely.
The upper horizon of this soil has a lighter color, its structure is loose. This is influenced by malting. Light chestnut soils are divided according to genera in the same way as others. Salt and salt marshes in light soil are more clearly manifested and are zonal in nature.
Using
The soil of the steppes, especially dark chestnut, has sufficient nutrient reserves. She has a high fertility. Wheat, millet, corn, sunflower, gourds and horticultural crops are grown on it. Productivity is much higher if phosphate, potash, nitrogen fertilizers are added to the soil and moisture is retained in it.
Chestnut soil without dark or light shades is more often used for grasslands, pastures, arable lands. But it is suitable for growing the above crops. On light chestnut soils, various crops can be grown only with regular irrigation.
Saline chestnut soils are characterized by unenviable fertility. Therefore, chemical and biological reclamation is used to increase it. Sometimes it’s enough to plow the earth deeply.
disadvantages
- Light chestnut, chestnut and saline soils of the steppes have a humus layer of small thickness. This cannot provide the normal habitat for the rooting layer.
- The compacted horizon lies relatively shallow. This violates the water regime of the soil and prevents the roots of plants from penetrating deeper.
- Saline soils have an increased concentration of alkali, which makes it necessary to oxidize the soil before using it.
- Steppe soils lack moisture and nutrients, especially light chestnut.
A person should help chestnut, low-power, low-structural and alkaline soils to become powerful, rich in humus and nutrients. It is necessary to systematically irrigate the soil to replenish its water supply, add organic and mineral fertilizers to it, and observe the latest agricultural techniques.