Classification of chernozem soils. What is black soil? Characteristics and features of soil use Basic information about chernozem soil
The first scientific provisions on the origin of chernozem are in the works of M.V. Lomonosov (mid-18th century), who believed that these soils were formed as a result of the decomposition of plant and animal organisms. At the end of the 18th - beginning of the 19th centuries. P. Pallas et al. put forward a hypothesis of the marine origin of chernozem and considered it as marine silt remaining after the retreat of the Caspian and Black Seas. This hypothesis only has historical significance; it reflects the concept of soil as a geological formation that existed at that time. The hypothesis of the swamp origin of chernozem also turned out to be untenable. Its supporters (E.I. Eichwald and others, mid-19th century) believed that in the past the zone of chernozem soils was tundra, heavily swamped spaces; The decomposition of swamp vegetation under the conditions of the subsequently established warm climate led to the formation of chernozem. The theory of the plant-terrestrial origin of chernozem (F.I. Ruprecht, V.V. Dokuchaev, etc.) connects their formation with the settlement and development of meadow-steppe and steppe herbaceous vegetation. This theory is most fully presented in the work of V.V. Dokuchaev “Russian Chernozem” (1883), which proved that chernozem was formed as a result of the close interaction of herbaceous vegetation, climate, terrain, parent rock and other soil-forming factors; the consequence of this process is the accumulation of humus.
Herbaceous vegetation leaves in the soil every year large number litter - plant residues, 75-85% of which are roots. The hydrothermal conditions of the steppe and forest-steppe zones favor the humification process, which results in the formation of complex humic compounds (mainly humic acids), which give the soil profile a dark color. Best conditions for the humification process are created in spring and early summer. At this time, the soil has a sufficient supply of moisture from autumn-winter precipitation and snowmelt, and a favorable temperature regime. During the period of summer drying, microbiological processes noticeably weaken, which protects humic substances from rapid mineralization. During the decomposition of plant residues rich in ash elements and nitrogen, bases are formed (especially a lot of calcium), which saturate humic substances. This contributes to their fixation in the soil in the form of humates and the preservation of a neutral or close to it reaction in the upper horizons of chernozem.
Chernozem formation occurs most intensively in the forest-steppe zone, where better moisture promotes more powerful development of herbaceous vegetation and active humification of its remains. In the steppe zone, insufficient moisture determines a shallower depth of root penetration, a decrease in the amount of litter entering the soil, and its more complete decomposition.
2. Types of black soil
Chernozem is divided into two gradations: according to the thickness of the humus layer and according to the humus content. Let's look at each gradation in more detail.
According to the thickness of the humus layer, chernozem is divided into:
· heavy-duty (thickness more than 120 cm);
· powerful (120 – 80 cm);
· medium-power (80 – 40 cm);
· low-power (less than 40 cm).
· obese (more than 9%) – black in color;
· medium humus (6 – 9%) – black color;
· low humus (6 – 4%) – dark gray color;
· low humus (less than 4%) – gray color;
· microhumus (less than 2%) – light gray color.
According to the type of chernozem there are:
· podzolized chernozems;
· leached chernozems;
· typical chernozems;
· ordinary chernozems;
· southern chernozems.
There are also mycelial-carbonate chernozems (Azov and Ciscaucasia), which are formed in areas with warm winters (the soil does not freeze), and chernozems that develop under conditions of winter freezing. Depending on the salinity, ordinary, carbonate, solonetsic, solonetzic-solonchakous and others are distinguished.
3. Layers of black soil
As mentioned above, chernozem can be divided into several types - layers: depending on the thickness of the humus layer (A and B1) - low-thick (less than 40 cm), medium-thick (40-80 cm), powerful (80-120 cm) and heavy-duty (more than 120 cm). We present the characteristics of the chernozem layers in the form of a summary table (Table 1).
Table 1 – Comparative characteristics layers of black soil
4. Properties of chernozem
Chernozems have good water-air properties, are distinguished by a lumpy or granular structure, a content of calcium in the soil absorption complex from 70 to 90%, a neutral or almost neutral reaction, increased natural fertility, intense humification and a high, about 15%, content of humus in the upper layers .
Chernozem has the largest amount of humus in its composition, which determines its high fertile properties. Chernozem also contains a large number of other useful substances, necessary for plants: nitrogen, sulfur, phosphorus, iron. Chernozem has a dense lumpy structure; the most fertile southern chernozem is even called “fat.”
Because of its fertility, black soil has always been highly valued throughout the world. And now black soil is the best type of soil for growing vegetables, fruits, and berries. For some plants, peat, sand or compost should be mixed into the chernozem to loosen the soil, since chernozem itself is not very loose.
5. Areas of distribution
Black soil area globe about 240 million hectares. They are confined to Eurasia, North and South America. In Eurasia, the black earth zone (the largest) covers Western and South-Eastern Europe (Hungary, Bulgaria, Austria, Czech Republic, Yugoslavia, Romania), extending in a wide strip to Russian Federation and continues in Mongolia and China. In North America, chernozems occupy some states of the Western United States and the southern provinces of Canada; in South America they are located in the south of Argentina and in the southern foothills of Chile.
In Russia, chernozems are widespread in the central regions, the North Caucasus, the Volga region and Western Siberia. Very fertile and almost completely plowed. The black soil zone is the most important agricultural region, in which more than 50% (130 million hectares) of arable land in our country is located. Winter and spring wheat are grown here, sugar beets, sunflower, flax, buckwheat, beans, livestock farming, fruit growing, vegetable growing and viticulture are developed.
6. Application of black soil
Chernozem is ideal for any type of planting. It does not require additional processing and the use of organic and mineral fertilizers. In conditions of good moisture, chernozem is very fertile - it can be used for growing grain, vegetable and fodder crops, for growing gardens and vineyards, for landscaping work in landscape design.
Most often, chernozem is used to form a certain reserve of soil fertility. The addition of chernozem to even the most depleted soil leads to its improvement, restoration of all its characteristics, especially water permeability, and enrichment with nutrients. A particularly significant effect is noticeable when using chernozem on light sandy and sandy loam soils.
Chernozem can be used separately or as part of soil mixtures. It should be said that a single use of chernozem on a site does not solve the problem of fertility once and for all. Over time, the microbiological composition of the soil changes, and at the same time the content of nutrients decreases.
1. Akhtyrtsev B.P., Akhtyrtsev A.B. Soil cover of the Central Russian Black Earth Region. Ed. Voronezh University, 1993
2. Aderikhin P.G. Soils, their genesis, properties and brief agricultural characteristics. Ed. Voronezh University, 1993
3. Akhtyrtsev B.P., Efanova E.V. Humus of subtypes of Central Russian chernozems of different granulometric composition. Ed. VSU, 1999
5. Orlov D.S. Soil chemistry. M.: Publishing house. Moscow un-ta. 1992.
6. Shcheglov D.I. Chernozems of the center of the Russian plain and their evolution under the influence of natural anthropogenic factors. Ed. "Science", Russian Academy Sciences, 1999.
Aderikhin P.G. Soils, their genesis, properties and brief agricultural characteristics. Ed. Voronezh University, 1993
Shcheglov D.I. Chernozems of the center of the Russian Plain and their evolution under the influence of natural anthropogenic factors. Ed. "Science", Russian Academy of Sciences, 1999.
Glazovskaya M.A., Soils of the world, part 1-2, M., 2002-73.
Orlov D.S. Soil chemistry. M.: Publishing house. Moscow un-ta. 1992.
Akhtyrtsev B.P., Efanova E.V. Humus of subtypes of Central Russian chernozems of different granulometric composition. Ed. VSU, 1999
Glazovskaya M.A., Soils of the world, part 1-2, M., 2002-73.
Akhtyrtsev B.P., Akhtyrtsev A.B. Soil cover of the Central Russian Black Earth Region. Ed. Voronezh University, 1993
The conditions necessary for the formation of these soils are created within the steppe and forest-meadow-steppe regions of the subboreal belt of Eurasia and North America. In Europe, they are common on the Danube low-lying plains, stretching in a strip through Moldova, Ukraine, the central parts of the Russian Plain, the North Caucasus and the Volga region. To the east of the Urals, vast areas of black soil extend into the southern part of Western Siberia and northern Kazakhstan. Some areas of these soils are confined to the plains and foothills of Altai, the Minusinsk Basin, and also to the basins of Transbaikalia. In North America, chernozems are mainly formed in the Great Plains.
The climate of the chernozem distribution zone is continental or moderate continental with warm summers and moderately cold or even cold winters. The annual temperature range is 30-50 0 C. During the year, precipitation falls from 300 to 600 mm, in the North American steppes - up to 750 mm. Maximum atmospheric humidity occurs at summer period However, at this time the highest average monthly temperatures are observed (in July 20-25 ° C), as a result of which a significant proportion of summer precipitation evaporates. Precipitation is uneven throughout the summer, with heavy rainfall followed by long periods of drought. The average annual moisture coefficient is in the range of 0.8-0.5, and in the warm period of the year it sometimes drops to 0.3. Thus, in summer, chernozems are characterized by periodic drying, but in spring and autumn, due to the infiltration of melt and rainwater, a significant part of their profile is noticeably moistened. In a number of regions (in Western Siberia, Transbaikalia, etc.) chernozems freeze to great depths in winter.
For the most part, chernozems develop on loamy rocks - loess or loess-like sediments, which are characterized by fairly good water permeability, porosity and carbonate content. Black soils of the European part of Russia, Ukraine, Western Siberia and the Central Plains of the USA are mainly confined to such rocks. In Canada, the chernozem zone penetrates the boundaries of ancient glaciation, where glaciolacustrine and moraine deposits serve as soil-forming rocks. In Kazakhstan and the Urals, these soils are sometimes formed on carbonate-free eluvium of dense rocks.
The most characteristic relief in the areas where chernozems are formed is flat, with varying degrees of development of the ravine-gully network. Chernozems are widespread in the uplands (Central Russian, Dnieper, etc.), lowlands (Middle Danube, West Siberian), in the foothills (Altai, Sayan) and in extensive depressions (in Transbaikalia). As a rule, the terrain conditions provide fairly good soil drainage.
Chernozems develop under herbaceous steppe associations. The nature of the vegetation cover in areas where chernozems are distributed changes due to the peculiarities of hydrothermal conditions. Areas with relatively high atmospheric humidity include meadow steppes, the tall and dense grass of which is represented by various types of forbs, legumes and cereals. In moderately arid steppes, feather grass-forbs and forbs-feather grass vegetation predominates. Dry steppes are formed by feather grass-fescue (or fescue-feather grass) more sparse associations.
Steppe vegetation supplies the soil with a large amount of organic matter. Herbaceous plants in the steppe die off annually entirely or in a significant part; in annuals, both aboveground and underground organs die off; in perennials, the entire aboveground part and a significant proportion (about one third) of the root systems die off. Especially a lot of organic residues end up in the soil in meadow steppes.
When moving to feather grass-forb and feather grass-fescue steppes, the amount of plant residues entering the soil consistently decreases.
Ground and root litter of steppe vegetation is rich in nitrogen and ash elements. Compared to forest litter (especially coniferous), it contains less waxes, resins, tannins, and more calcium, magnesium, phosphorus, which favors humification processes in steppe soils.
Powerful root system steppe vegetation is a kind of biological barrier that retains in the soil many of the ash nutrition elements necessary for plants. They are actively involved in the biological cycle of substances, and thus their leaching from the sphere of soil formation is prevented. Unplowed chernozems are abundantly populated by diverse soil fauna. The upper horizons are inhabited by worms, larvae of beetles, weevils and other insects. The upper horizons of the soil are loosened and mixed by small diggers, voles, etc. Large diggers also live here - marmots, gophers, which make the soil even more air- and water-permeable.
Chernozems are characterized by high microbiological activity, the maximum of which occurs in spring and autumn periods when optimal hydrothermal conditions are created in the soils. In summer, microbiological activity is sharply reduced due to drying out of the soil, and in winter - as a result of its freezing.
Thus, in areas where chernozems are distributed, the following set of soil formation conditions develops:
a) the presence of herbaceous vegetation, which supplies the soil with a large amount of organic residues rich in ash elements and nitrogen;
b) the richness of soil-forming rocks in calcium carbonates or primary calcium-containing minerals;
c) continental climate with alternating periods of wetting and drying, warming and freezing of soils.
The morphological profile of typical chernozems includes the horizons indicated below.
A horizon of steppe felt lies on the surface (if the soils are plowed, this horizon is absent).
Below, a powerful humus-accumulative horizon Al t is developed - dark gray, almost black, fine-grained or lumpy-grained, loose, densely penetrated by roots herbaceous plants(especially in the upper part) and worm passages.
A1B - transitional humus horizon, brownish-gray, gray color weakens towards the bottom, granular-lumpy, less loose than the overlying one; in the lower part it boils and contains carbonates in the form of pseudomycelium and tubes;
In sa - illuvial-carbonate horizon, brown or pale-brown with whitish spots of nodular carbonate formations (white-eyes); has a lumpy-nutty structure, compacted;
WITH sa - soil-forming rock, distinguished by a decrease in the content of carbonate accumulations and deterioration of the structure.
According to the total thickness of the A1 h and A1B horizons, chernozems are divided into types: thin - less than 40 cm, medium-thick - 40-80 cm, thick - 80-120 cm and super-thick - more than 120 cm.
Based on the depth of the carbonate horizon, subtypes of chernozems are distinguished: typical (the profile described above), leached and podzolized (between the A1h and Bca horizons there is a horizon leached from carbonates, and sometimes with signs of podzolization), as well as ordinary and southern (in which carbonates are present respectively in the middle part of the A1B horizon and in the lower part of the A1 horizon).
According to the humus content, chernozems are divided into: high-humus, or fat (more than 9%), medium-humus (6-9%) and low-humus (less than 6%). Within the humus profile, organic matter gradually decreases with depth (Fig. 17.3). Chernozems are soils with the widest possible ratio of humus C g / C f - from 1.5 to 2.0 and even slightly more. Among the humus fractions, humic acids associated with calcium predominate. The humus horizon contains significant amounts of nitrogen, potassium and phosphorus.
The reaction of the soil solution in the upper part of the profile of typical chernozems is close to neutral. In carbonate horizons it becomes slightly alkaline. The absorption capacity due to the large number of organic colloids is very high, especially in the upper horizons (from 30 to 60-70 mg. × eq. per 100 g of soil). The soil absorption complex is completely saturated with bases, among which calcium predominates (75-80%). The remaining 20-25% comes from absorbed magnesium. Gross chemical composition is practically the same in all soil horizons, as is the chemical composition of the clay fraction. A small maximum of silt is found in the upper part of the profile. In the Bca horizon, the accumulation of calcium carbonates is analytically confirmed.
Rice. 17.3. Chernozem profile. Genetic horizons: 1 - humus-accumulative humate-calcium; 2-transitional; 3 - illuvial-carbonate; 4 - siallitic-carbonate soil-forming rock. Composition of the clay fraction: 5 - illite-montmorillonite
Chernozems have good physical properties: water-resistant structure, high air and water permeability, significant water-holding capacity.
Most of the properties of chernozems are determined by the peculiarities of the processes of humus formation and humus accumulation occurring in these soils. Significant quantities of herbaceous residues entering the soil annually, their high ash content and the richness of ash in bases are among the determining factors for the deep humification of organic matter. In relatively humid and fairly warm spring and autumn periods, when microflora (mainly bacterial) is maximally activated in chernozems, intensive transformation of organic residues occurs in the direction of producing mainly humic acids. In the soil at this time, a neutral reaction of the environment predominates; the area of humus formation contains a large amount of alkaline earth bases and, as a result, stable organo-mineral compounds of humic acids, primarily calcium humates, are formed. Fulvic acids are formed significantly less and only in the form associated with humic acids. There are no free, aggressive fulvic acids in chernozems.
In parallel with the humification of organic matter in the spring and autumn periods, its very intense mineralization occurs. However, the results of the latter process do not manifest themselves in a sharp decrease in humus content, since it is significantly inhibited in summer and winter. In dry summer and cold winter time chemical transformations of newly formed humic substances stop. Drying and freezing of the soil mass lead to the fact that these substances are strongly dehydrated, coagulate and pass into a sedentary state, almost irreversibly losing solubility. It is the alternation of periods of dormancy and active humus formation that contributes to the formation of large reserves of humus in chernozems.
The development of accumulative phenomena in chernozems is also favored by other features of the genesis of these soils. The combination of a large number of organic colloids with a high absorption capacity and the almost complete saturation of the soil absorption complex with doubly charged cations (calcium and magnesium) lead to the fact that the colloids are in a stable, strongly coagulated state. They are consolidated into structural units and do not move along the profile.
The formation of a water-resistant lumpy-grained structure in chernozems is also facilitated by the abundant root system of herbaceous plants, which densely penetrates the upper soil horizons. The roots of grasses divide the soil mass into numerous small lumps and compact them. When dead roots decompose, the humic substances formed from them glue the soil particles together.
The structuring of chernozems is also associated with the activity of abundant soil fauna, especially earthworms. Many structural aggregates in these soils are zoogenic in nature.
The good structural condition of soils creates water and air soil regimes that are very favorable for plant life: inside soil aggregates, capillary-suspended moisture can be retained in the capillary spaces between parts, while the spaces between lumps can be filled with air at the same time.
The genesis of chernozems is largely determined by the processes of movement and transformation of mineral water-soluble salts in the soil profile. As mentioned earlier, black soils steppe zone exist in conditions of non-flushing water regime. The usual soaking depth is about 2 m. As a result of this upper part The profile of chernozem soils turns out to be devoid of water-soluble salts, and at a certain depth illuvial salt horizons are formed. The illuvial carbonate horizon is especially characteristic of chernozems. Its formation involves both biogenic calcium carbonates and carbonates inherited by the soil from the rock. The mechanism of this process is as follows.
Carbon dioxide released during the decomposition of organic residues in the upper part of the soil profile combines with calcium released during the mineralization of plant residues and forms calcium bicarbonate. Part of the produced carbon dioxide, dissolving in soil moisture, contributes to the conversion of insoluble rock carbonates into more soluble bicarbonates according to the scheme CaC0 3 + C0 2 + H 2 0 -> Ca (HC0 3) 2. With downward moisture flows, bicarbonates move down the profile, where they turn into various shapes carbonate neoplasms (white eye, lime deposits, pseudomycelium, etc.).
Many researchers believe that the amount of carbonates in chernozems depends on the degree of initial carbonate content of the source rocks. However, there is a point of view according to which the carbonate content of rocks is not the root cause, but a consequence of chernozem and more in a broad sense steppe soil-forming process (JI.C. Berg, S.S. Neustruev, B.B. Polynov). Various facts are cited to prove this. Thus, on the primary carbonate-free eluvium of granites in a steppe climate and under steppe vegetation Soils with a carbonate horizon are formed. In this case, the entire thickness of the loose substrate is calcified during the process of soil formation due to the weathering of aluminosilicate calcium-containing minerals and the entry a certain amount calcium carbonates onto the soil surface with precipitation and dust masses.
In some chernozems of the driest part of the steppe zone, at the very bottom of the profile, easily soluble salts such as gypsum, chlorides and sulfates of sodium and magnesium can also be found. The formation of such illuvial-salt horizons is associated, as a rule, with the initial salinity of the rocks and the leaching of these salts from the upper and middle parts of the profile during the process of soil formation.
Depending on the depth of soil wetting and the frequency of relatively wet years, gypsum and salt illuvial horizons are located either directly below carbonate horizons, marking the boundary of the soil and the parent rock, or are located below the soil boundaries, already in the thickness of the parent rock, as is observed in most chernozems.
The age of chernozems is estimated at several tens of thousands of years. In order for a more or less mature chernozem soil profile with a characteristic thick humate-calcium horizon to be formed, according to various estimates it takes time from 3-5 thousand to 10 thousand years. Some researchers believe that such properties of chernozems as high humus content, the presence of nodular carbonate formations and a general high calcification of the profile, at least in a number of territories, are of a relict nature and inherited from past periods of development of these soils in conditions of close occurrence of mineralized soils. groundwater, i.e. chernozems have signs of paleohydromorphism (V.A. Kovda, E.M. Samoilova, etc.).
Chernozems are some of the most fertile soils in the world. They have chemical properties favorable for agriculture (rich in humus, elements mineral nutrition) and physical properties (good structure, air and water permeability). These soils produce the highest yields of grains, sugar beets, sunflowers and many other crops. At the same time, their irrational exploitation often leads to degradation - loss of humus, overcompaction, erosion and secondary salinization.
Chernozem is a highly fertile land, dark in color, chernozem is rich in humus, with a pronounced granular-lumpy structure, usually chernozem is formed in forests, loams or clays, in a temperate continental climate.
Chernozem is rightfully considered the best soil for agriculture, and chernozem is formed under perennial herbaceous vegetation, in climatic conditions steppe and forest-steppe territorial zones.
On the territory of our country, chernozems are found in the central chernozem regions, the Volga region, Western Siberia and the North Caucasus, there are many chernozems in Ukraine, as well as in some European countries, China, South and North America.
Chernozem, as a soil, is rich in humus, formed on loess-like loams or clays, usually in a temperate continental climate, with periodic precipitation, under perennial vegetation, usually herbaceous.
Conditions of soil formation of chernozems
For persistent soil formation of chernozems, the following conditions are necessary: the climate is temperate, or moderate continental, there must be an alternation of moistening and drying, with a predominance of positive temperature regime. The average annual temperature should not be lower than +3 +7 degrees Celsius, and the annual precipitation amount should be 300-600 mm.
The relief of the chernozems is undulating-flat, in some places cut by depressions, ravines, and river terraces.
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The vegetation on chernozems is perennial herbaceous, meadow-steppe. In appropriate climatic conditions, its decomposition occurs, as a result of which humus compounds are formed, which, accordingly, accumulate in the upper layers of the soil.
Together with humus in chernozem soil, in the form of complex organic and mineral compounds, plant nutrients such as nitrogen, iron, phosphorus and sulfur are formed, etc. site/node/2879
About the properties of black soil
Chernozems in their properties - have fairly good water-air qualities, but chernozem is distinguished by a lumpy or granular structure, a high calcium content in the soil from 70 to 90%, and is characterized by a neutral or almost neutral reaction.
Chernozem on earth is valued - increased fertility, natural and intense humification, quite high, about 15%, humus content in the upper layers of the soil.
What types of black soil are there?
Chernozems are divided into the following types:
Podzolized chernozem - these chernozems are common in broad-leaved grassy forests;
Leached chernozem - such chernozems are formed under the meadow forb-grass steppes of the forest-steppe zone;
Typical chernozem - the formation of this type of chernozem occurs under forb-grass soil, i.e. meadow-steppe, vegetation in forest-steppe zones, loess-like and cover loams;
Ordinary chernozem - these chernozems can be found in the northern part of the steppe zone, and they are formed under forb vegetation;
Southern chernozems - these chernozems are formed under fescue-feather grass vegetation; they can be found in the southern part of the steppe zone.
Having a large amount of humus in its composition, chernozem is valued as a highly fertile soil that produces a high and stable harvest. It also contains a fairly large amount of other useful substances for fertility, so necessary for plants: nitrogen, sulfur, iron and phosphorus. Chernozem in its structure has a dense lumpy structure, and southern chernozem is considered one of the most fertile, it is even called “fat chernozem”.
Because of their fertility, black soils have always been valued throughout the world. And now, in modern times- black soil is best view land for growing vegetables, fruits, berries, trees and shrubs on it. Although it is worth knowing that for some plants, when planting them in the ground (chernozem), peat, sometimes sand or compost should be mixed in to loosen the earth (soil), because chernozem itself is quite dense, it is not very loose.
Application of chernozem
As we already know, black soil is the best soil for plants. As the name suggests, chernozem is dark-colored land (soil) that is very fertile.
Chernozem is used as plant soil and is used when laying out lawns, in gardening and as garden soil, etc. Chernozem is also used when cultivating land with a high clay content, land with poor drainage, to create a favorable air-water regime, and also, if necessary, to create a loose, lumpy soil structure.
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All about the composition and properties of chernozem
Black soil is the richest soil in nutrients. In such a plot there are always high yields of vegetables, berries, and ornamental plants delight with lush growth and flowering.
Soil composition
Chernozems vary in composition, but are always dark and charcoal in color. Formed over thousands of years in places with high humidity and moderate air temperatures. The fertile layer is formed by the remains of vegetation, which is processed by microorganisms and enzymes for hundreds of years.
Source: Depositphotos. Chernozem soil is black and lumpy
Fertile soils are formed in forests, forest-steppe zones, meadows and even on loams. They differ in the content of useful substances and a high percentage of vermicompost.
Composition of chernozem:
- humus up to 9%;
- humic acids;
- minerals (calcium, phosphorus, potassium);
- other organic compounds.
Due to the percentage of humus, chernozem is also called fatty soil, implying nutritional value for plants. If you squeeze a lump of earth in your hand, it will leave a greasy mark. The best fertile lands are formed naturally in the southern regions, where there has been an abundance of vegetation for centuries.
Properties and characteristics
Nutritious soils are valued not only for their content of humus and other components valuable for plants. This is also an ideal consistency - granular-lumpy, which allows air to pass through and retains moisture without petrification.
Special soil properties:
- neutral ph;
- resistant to weathering, washing out and compaction;
- optimal balance of living microorganisms;
- Suitable for growing most cultivated plants.
The only negative is the need to additionally add loosening mixtures to improve the structure and looseness. Add sand, peat or vermiculite.
Nutrient dark soils are prone to depletion when long-term use. Therefore, after a few years they require fertilization. The difficulty lies in determining the dose of nutrients. If chernozem is brought to a site from another region, its fertility decreases in the new place, and life cycle microorganisms slow down before adaptation.
In plant growing, soil rich in vermicompost is considered ideal for obtaining high yields. Chernozem is added to poor areas carefully, dug up from the existing soil with a fork, avoiding compaction. This procedure is carried out in the fall in order to obtain the basis for the harvest by the new season.
INTRODUCTION
Russia contains more than 10% of the world's farmland. According to media reports, our country remains the last large reserve of agricultural land on the planet, at least in the “civilized” world. Therefore, knowledge about our land resources suitable for farming agriculture, purchased in lately exceptional importance. According to the founder of Russian soil science V.V. Dokuchaev, “our plant-terrestrial soils (of which chernozem is a representative) are not some kind of mechanical, random, lifeless mixtures, but, on the contrary, are independent, definite, natural-historical bodies subject to known laws” (1).
1. CHARACTERISTICS OF CHERNOZEM
Compound
Chernozem is a rather heterogeneous mass: here you can find pieces of quartz, flakes of humus, and sometimes fragments of limestone, feldspar and even granite pebbles.
It is very rich in humus (dark organic matter, one might say, natural manure) and the most important easily soluble plant nutrients, such as: phosphoric acid, nitrogen, alkalis, etc. Typical chernozem is usually fine-grained, crumbly and always reveals a close relationship (both in structure and composition) with the underlying soil rocks (subsoil), which themselves (loess) in the vast majority of cases are very rich in soluble nutrients and are endowed with excellent physical properties.
Structure
Chernozem is a plant-terrestrial soil whose thickness on average is about 60 cm. Under the turf, 5–8 cm thick, there is a dark, homogeneous, loose mass - humus, consisting of grains or grains, sometimes round, but more often representing irregular polyhedra. This horizon in unplowed, virgin places is overcrowded with hundreds of thousands of living and dead underground parts of herbaceous plants. The average thickness of the A horizon (accepted designation according to V.V. Dokuchaev) is 30–45 cm. Below, the soil horizon merges completely imperceptibly with the transition horizon, which indeed, in all its features (physical and chemical), represents a gradual transition from the upper (A) horizon to the lower (C) subsoil. The thickness of horizon B is also 30-45 cm. The subsoil - the base (C) in the vast majority of cases consists of loess (light yellow, very loose, carbonate-rich loam), but often it also consists of sandy loam, chalk, limestone, marl, etc. ., and always the subsoil (C) gradually passed into the upper soil horizons (A and B), giving them a strictly defined mineral character. Thus, chernozem in all natural sections, not disturbed (in one way or another) represents a gradual, closest genetic connection with the subsoil, whatever its composition.
Types
The following subtypes of chernozem soils are distinguished:
Podzolized chernozems,
Leached chernozems,
Typical chernozems,
Ordinary chernozems,
Southern chernozems.
Properties
1. Due to its composition, chernozem always has more or less dark color and relates favorably to heat and moisture. Color is a typical external feature: the color of chernozem, whether it contains humus up to 15% or no more than 3–4%, always turns out to be more or less dark,
2. Replenishment of chernozem, that is, the ability to become much more ripe (in the agricultural sense), that is, one whose subarable horizon is approximately the same composition in structure as the arable one.
3. Another typical constant feature is the average thickness of chernozem, which ranges from 60 to 140 cm.
2. AREAS OF DISTRIBUTION
According to V.V. Dokuchaev chernozem is always and everywhere the result of cumulative activity:
a) bedrock (subsoil), on which it currently lies;
b) the climate that surrounds this soil now and surrounded it in the past (latitude and longitude, the nature of precipitation, temperature, winds);
c) wild vegetation that grew there and still grows to this day in places untouched by culture.
The areas of distribution of fertile plains in the world are: the steppes of Europe and Asia, the savannas of Africa, Australia, the Northern prairies and the pampas South America, Venezuela, Brazil.
On the territory of Russia, chernozems are widespread in the regions of the Volga region, the Urals, North Caucasus, Lower Don and Western Siberia. The heart of the black earth strip is Voronezh and Saratov region. The volume of chernozem soils in the world is 48%, in Russia - 8.6%, which is 1.53 million km 2.
3. APPLICATION
Chernozem soils can withstand long-term cultivation without any fertilizer and, whenever climatic conditions are favorable, they produce excellent harvests rice, grains, sunflowers, beets, feed, fruits, grapes and other technical and vegetable crops. The natural fertility of chernozem soils makes it possible to fully satisfy the population's need for food, provides a significant part of the raw materials for light industry, and ensures livestock breeding.
