Soils characteristic of natural areas. The main types of soils in Russia, their brief description. Stiff-leaved evergreen forests and shrubs

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THE SOIL- the most surface layer of the earth's land, resulting from changes in rocks under the influence of living and dead organisms (vegetation, animals, microorganisms), solar heat and atmospheric precipitation. The soil is a completely special natural formation with only its inherent structure, composition and properties. The most important property of the soil is its fertility, i.e. the ability to ensure the growth and development of plants. To be fertile, the soil must have a sufficient amount of nutrients and a supply of water necessary for plant nutrition; it is precisely by its fertility that the soil, as a natural body, differs from all other natural bodies (for example, barren stone), which are not able to provide the need for plants at the same time. and the joint presence of two factors of their existence - water and minerals.

Soil is the most important component of all terrestrial biocenoses and the biosphere of the Earth as a whole; numerous ecological connections of all organisms living on earth and in the earth (including humans) with the lithosphere, hydrosphere and atmosphere go through the soil cover of the Earth.

The role of soil in the human economy is enormous. The study of soils is necessary not only for agricultural purposes, but also for the development of forestry, engineering and construction. Knowledge of soil properties is necessary for solving a number of problems in health care, exploration and extraction of minerals, the organization of green zones in the urban economy, environmental monitoring, etc.

Soil Science: History, Relationship with Other Sciences.

The science of the origin and development of soils, the patterns of their distribution, ways of rational use and increasing fertility is called soil science. This science is a branch of natural science and is closely related to the physical and mathematical, chemical, biological, geological and geographical sciences, based on the fundamental laws and research methods developed by them. At the same time, like any other theoretical science, soil science develops on the basis of direct interaction with practice, which checks and uses the revealed patterns and, in turn, stimulates new searches in the field of theoretical knowledge. By now, large applied sections of soil science have been formed for agriculture and forestry, irrigation, construction, transport, prospecting for minerals, health care and environmental protection.

Since the systematic occupation of agriculture, mankind, first empirically, and then using scientific methods, studied the soil. The most ancient attempts to assess various soils are known in China (3 thousand BC) and Ancient Egypt. In ancient Greece, the concept of soil was formed in the process of the development of ancient natural-philosophical natural science. During the period of the Roman Empire, a large number of empirical observations of soil properties were accumulated and some agronomic methods of soil cultivation were developed.

The long period of the Middle Ages was characterized by stagnation in the field of natural science, but at the end of it (with the beginning of the disintegration of the feudal system), interest in the study of soils reappeared in connection with the problem of plant nutrition. A number of works of that time reflected the opinion that plants feed on water, creating chemical compounds from water and air, and the soil serves them only as a mechanical support. However, by the end of the 18th century. this theory was replaced by Albrecht Thayer's humus theory, according to which plants can only feed on soil organic matter and water. Thayer was one of the founders of agronomy and the organizer of the first higher agronomic educational institution.

In the first half of the 19th century. the famous German chemist Justus Liebig developed the mineral theory of plant nutrition, according to which plants assimilate minerals from the soil, and only carbon in the form of carbon dioxide from humus. Yuri Liebikh believed that each harvest depletes the supply of minerals in the soil, therefore, in order to eliminate this deficiency of elements, it is necessary to apply factory-prepared mineral fertilizers to the soil. The merit of Liebig was the introduction of the use of mineral fertilizers into the practice of agriculture.

The value of nitrogen for soil was studied by the French scientist J. Yu. Boussingo.

By the middle of the 19th century. accumulated extensive material on the study of soils, but these data were scattered, not listed in the system and not generalized. There was not even a single definition of the term soil for all researchers.

The outstanding Russian scientist Vasily Vasilyevich Dokuchaev (1846-1903) became the founder of soil science as an independent natural-historical science. Dokuchaev was the first to formulate the scientific definition of soil, calling the soil an independent natural-historical body, which is the product of the combined activity of the parent rock, climate, plant and animal organisms, soil age and, in part, the terrain. All the factors of soil formation that Dokuchaev spoke about were known before him, they were consistently put forward by different scientists, but always as the only determining condition. Dokuchaev was the first to say that the emergence of soil occurs as a result of the combined action of all factors of soil formation. He established a view of the soil as an independent special natural body, equivalent to the concepts of a plant, animal, mineral, etc., which arises, develops, continuously changes in time and space, and with this he laid a solid foundation for a new science.

Dokuchaev established the principle of the structure of the soil profile, developed the idea of ​​the regularity of the spatial distribution of certain types of soils covering the land surface in the form of horizontal or latitudinal zones, established vertical zoning, or zonality, in the distribution of soils, which is understood as the regular replacement of some soils by others as they rise from the foot to the top of the high mountains. He also belongs to the first scientific classification of soils, which was based on the entire set of the most important characteristics and properties of the soil. Dokuchaev's classification was recognized by world science and the names he proposed “black earth”, “podzol”, “saline”, “solonetz” have become international scientific terms. He developed methods for studying the origin and fertility of soils, as well as methods for mapping them, and even in 1899 compiled the first soil map of the Northern Hemisphere (this map was called the "Scheme of Soil Zones of the Northern Hemisphere").

In addition to Dokuchaev, a great contribution to the development of soil science in our country was made by P.A. Kostychev, V.R. Williams, N.M. Sibirtsev, G.N. Vysotsky, P.S. Kossovich, K.K. Gedroits, K. D. Glinka, S. S. Neustruev, B. B. Polynov, L. I. Prasolov and others.

Thus, the science of soil as an independent natural formation was formed in Russia. Dokuchaev's ideas had a strong influence on the development of soil science in other countries. Many Russian terms have entered the international scientific lexicon (chernozem, podzol, gley, etc.)

Scientists from other countries have also carried out important studies for understanding the processes of soil formation and studying the soils of different territories. They are E.V. Gilgard (USA); E. Ramann, E. Blank, V. I. Kubiena (Germany); A. de Sigmond (Hungary); J. Milne (Great Britain), J. Aubert, R. Menien, J. Durant, N. Leneuf, G. Hérard, F. Duchaufour (France); J. Prescott, S. Stephens (Australia) and many others.

For the development of theoretical concepts and the successful study of the soil cover of our planet, business contacts between different national schools are necessary. In 1924 the International Society of Soil Scientists was organized. For a long time, from 1961 to 1981, a large and complex work was carried out to draw up the Soil Map of the World, in the compilation of which Russian scientists played a large role.

Soil study methods.

One of them is comparatively geographical, based on the simultaneous study of the soils themselves (their morphological characteristics, physical and chemical properties) and the factors of soil formation in different geographical conditions with their subsequent comparison. Nowadays, in soil research, various chemical analyzes, analyzes of physical properties, mineralogical, thermochemical, microbiological and many other analyzes are used. As a result, a definite connection is established in the change of certain soil properties with a change in soil-forming factors. Knowing the patterns of distribution of soil-forming factors, it is possible to create a soil map for a vast territory. It was in this way that Dokuchaev made the first world soil map in 1899, known as the "Schemes of the soil zones of the Northern Hemisphere."

Another method is the stationary research method. consists in the systematic observation of a soil process, which is usually carried out on typical soils with a certain combination of soil-forming factors. Thus, the method of stationary research clarifies and details the method of comparative geographical research. There are two methods for studying soils.

Soil formation.

The process of soil formation.

All rocks covering the surface of the globe, from the very first moments of their formation, under the influence of various processes, began immediately to collapse. The sum of the transformation processes of rocks on the Earth's surface is called weathering or hypergenesis. The collection of weathering products is called the weathering crust. The process of transforming the original rocks into the weathering crust is extremely complex and includes numerous processes and phenomena. Depending on the nature and causes of the destruction of rocks, physical, chemical and biological weathering is distinguished, which usually comes down to the physical and chemical effects of organisms on rocks.

Weathering (hypergenesis) processes spread to a certain depth, forming a zone of hypergenesis . The lower boundary of this zone is conventionally drawn along the top of the upper horizon of underground (stratal) waters. The lower (and most) part of the hypergenesis zone is occupied by rocks, to one degree or another altered by weathering processes. Here, the newest and ancient weathering crust is distinguished, formed in more ancient geological periods. The surface layer of the hypergenesis zone is the substrate on which the soil is formed. How does the process of soil formation take place?

In the process of weathering (hypergenesis), the original appearance of rocks, as well as their elemental and mineral composition, changed. Initially massive (i.e. dense and hard) rocks gradually turned into a fractured state. Examples of rocks crushed as a result of weathering are grit, sand, and clay. Becoming fragmented, the rocks acquired a number of new properties and features: they became more permeable to water and air, the total surface of their particles increased in them, increasing chemical weathering, new compounds were formed, including easily soluble in water compounds, and, finally, mountainous breeds acquired the ability to retain moisture, which is of great importance for providing plants with water.

However, the weathering processes themselves could not lead to the accumulation of plant food elements in the rock, and therefore could not turn the rock into soil. The easily soluble compounds formed as a result of weathering can only be washed out of rocks under the influence of atmospheric precipitation; and such an important biological element as nitrogen, consumed by plants in large quantities, is completely absent in igneous rocks.

Loose and water-absorbing rocks became a favorable environment for the life of bacteria and various plant organisms. Gradually, the upper layer of the weathering crust was enriched with the products of the vital activity of organisms and their dying off remains. The decomposition of organic substances and the presence of oxygen led to complex chemical processes, as a result of which the elements of ash and nitrogen food accumulated in the rock. Thus, the rocks of the surface layer of the weathering crust (they are also called parent, bedrock or parent rocks) became soil. Thus, the composition of the soil includes a mineral component corresponding to the composition of the bedrock, and an organic component.

Therefore, the beginning of the process of soil formation should be considered the moment when vegetation and microorganisms settled on the products of weathering of rocks. From that moment on, the crushed rock became soil, i.e. a qualitatively new body with a number of qualities and properties, the most essential of which is fertility. In this respect, all existing soils on the globe are a natural-historical body, the formation and development of which is associated with the development of all organic life on the earth's surface. Once it was born, the soil-forming process never stopped.

Factors of soil formation.

The development of the soil-forming process is most directly influenced by those natural conditions in which it proceeds, its features and the direction in which this process will develop depend on one or another combination of them.

The most important of these natural conditions, called factors of soil formation, are the following: parent (parent) rocks, vegetation, fauna and microorganisms, climate, terrain and soil age. To these five main factors of soil formation (which were also named by Dokuchaev) are now added by the action of waters (soil and ground) and human activity. The biological factor is always of leading importance, while the rest of the factors are only the background against which the development of soils in nature takes place, but they have a great influence on the nature and direction of the soil-forming process.

Parent rocks.

All existing soils on Earth originated from rocks, so it is obvious that they are most directly involved in the process of soil formation. The chemical composition of the rock is of the greatest importance, since the mineral part of any soil contains, basically, those elements that were part of the parent rock. The physical properties of the parent rock are also of great importance, since factors such as the granulometric composition of the rock, its density, porosity, and thermal conductivity directly affect not only the intensity, but also the nature of the ongoing soil-forming processes.

Climate.

The climate plays a huge role in the processes of soil formation, its influence is very diverse. The main meteorological elements that determine the nature and characteristics of climatic conditions are temperature and precipitation. The annual amount of incoming heat and moisture, the peculiarities of their daily and seasonal distribution, determine completely certain processes of soil formation. The climate affects the nature of the weathering of rocks, affects the thermal and water regimes of the soil. The movement of air masses (wind) affects the gas exchange of the soil and captures small particles of soil in the form of dust. But the climate affects the soil not only directly, but also indirectly, since the existence of one or another vegetation, the habitat of certain animals, as well as the intensity of microbiological activity is determined precisely by climatic conditions.

Vegetation, animals and microorganisms.

Vegetation.

The importance of vegetation in soil formation is extremely great and diverse. Penetrating the upper layer of the parent rock with the roots, the plants extract nutrients from its lower horizons and fix them in the synthesized organic matter. After the mineralization of dead plant parts, the ash elements contained in them are deposited in the upper horizon of the parent rock, thereby creating favorable conditions for the nutrition of the next generations of plants. So, as a result of the constant creation and destruction of organic matter in the upper horizons of the soil, the most important property for it is acquired - the accumulation, or concentration of elements of ash and nitrogen food for plants. This phenomenon is called the biological absorption capacity of the soil.

Due to the decomposition of plant residues, humus accumulates in the soil, which is of great importance in soil fertility. Plant residues in the soil are a necessary nutrient substrate and an essential condition for the development of many soil microorganisms.

In the process of decomposition of soil organic matter, acids are released, which, acting on the parent rock, enhance its weathering.

Plants themselves, in the process of their vital activity, secrete various weak acids with their roots, under the influence of which hardly soluble mineral compounds partially pass into a soluble form, and therefore into a form assimilated by plants.

In addition, the vegetation cover significantly changes the microclimatic conditions. For example, in the forest, compared to treeless areas, the summer temperature is lower, the humidity of the air and soil is increased, the wind force and evaporation of water above the soil are reduced, more snow, melt and rainwater accumulates - all this inevitably affects the soil-forming process.

Microorganisms.

Thanks to the activity of microorganisms inhabiting the soil, organic residues are decomposed and the elements contained in them are synthesized into compounds that are absorbed by plants.

Higher plants and microorganisms form certain complexes, under the influence of which various types of soils are formed. Each plant formation corresponds to a certain type of soil. For example, under the vegetation formation of coniferous forests, chernozem will never form, which is formed under the influence of meadow-steppe vegetation formation.

Animal world.

Animal organisms, of which there are a lot in the soil, are of great importance for soil formation. The most important are invertebrates living in the upper soil horizons and in plant debris on the surface. In the course of their life, they significantly accelerate the decomposition of organic matter and often produce very profound changes in the chemical and physical properties of the soil. Burrowing animals, such as moles, mice, ground squirrels, marmots, etc., play an important role. Repeatedly digging through the soil, they contribute to the mixing of organic substances with mineral substances, as well as to increase the water and air permeability of the soil, which enhances and accelerates the decomposition of organic residues in the soil ... They also enrich the soil mass with the products of their vital activity.

Vegetation serves as food for various herbivores, therefore, before entering the soil, a significant part of organic residues undergoes significant processing in the digestive organs of animals.

Relief

has an indirect effect on the formation of the soil cover. Its role is mainly reduced to the redistribution of heat and moisture. A significant change in the height of the terrain entails significant changes in temperature conditions (it gets colder with height). This is associated with the phenomenon of vertical zoning in the mountains. Relatively small changes in altitude affect the redistribution of atmospheric precipitation: low areas, hollows and depressions are always moistened to a greater extent than slopes and rises. The exposure of the slope determines the amount of solar energy coming to the surface: the southern slopes receive more light and heat than the northern ones. Thus, the features of the relief change the nature of the impact of climate on the process of soil formation. Obviously, in different microclimatic conditions, the processes of soil formation will proceed in different ways. Of great importance in the formation of the soil cover is the systematic washout and redistribution of fine earth particles by atmospheric precipitation and melt water over the relief elements. The significance of the relief in conditions of abundant precipitation is great: areas devoid of a natural runoff of excess moisture are very often subject to waterlogging.

Soil age.

Soil is a natural body that is in constant development, and the kind that all soils existing on Earth have today is only one of the stages in a long and continuous chain of their development, and individual present soil formations, in the past, represented other forms and in the future may undergo significant transformations even without abrupt changes in external conditions.

There are absolute and relative soil ages. The absolute age of soils is called the period of time elapsed from the moment the soil was formed to the present stage of its development. The soil arose when the parent rock came to the surface and began to undergo soil formation processes. For example, in Northern Europe, the process of modern soil formation began to develop after the end of the last ice age.

However, within the limits of different parts of the land, which were simultaneously freed from the water or ice cover, the soil will not always go through the same stage of its development at every given moment. This may be due to differences in the composition of the parent rocks, relief, vegetation, and other local conditions. The difference in the stages of soil development in one common area, which has the same absolute age, is called the relative soil age.

The development time of a mature soil profile for different conditions is from several hundred to several thousand years. The age of the territory in general and the soil in particular, as well as changes in the conditions of soil formation in the process of their development, have a significant impact on the structure, properties and composition of the soil. Under similar geographic conditions of soil formation, soils with different ages and developmental histories can differ significantly and belong to different classification groups.

The age of soils is therefore one of the most important factors that must be taken into account when studying a particular soil.

Soil and ground waters.

Water is the environment in which numerous chemical and biological processes take place in the soil. Where groundwater is shallow, it has a strong effect on soil formation. Under their influence, the water and air regimes of soils change. Groundwater enriches the soil with chemical compounds that they contain, sometimes causing salinization. Waterlogged soils contain an insufficient amount of oxygen, which causes the suppression of the activity of some groups of microorganisms.

Human economic activity affects some factors of soil formation, for example, on vegetation (deforestation, replacing it with herbaceous phytocenoses, etc.), and directly on the soil by mechanical processing, irrigation, application of mineral and organic fertilizers, etc. As a result, often soil-forming the processes and properties of the soil change. In connection with the intensification of agriculture, the influence of man on soil processes is constantly increasing.

The impact of human society on the soil cover is one of the sides of the overall human impact on the environment. Now the problem of destruction of the soil cover as a result of improper agricultural soil cultivation and human construction activities is especially acute. The second most important problem is soil pollution caused by chemicalization of agriculture and industrial and household emissions into the environment.

All factors do not influence in isolation, but in close interconnection and interaction with each other. Each of them affects not only the soil, but also each other. In addition, the soil itself in the process of development has a certain effect on all factors of soil formation, causing certain changes in each of them. So, due to the inextricable connection between vegetation and soils, any change in vegetation is inevitably accompanied by a change in soils, and, conversely, a change in soils, in particular, their moisture regime, aeration, salt regime, etc. inevitably entails a change in vegetation.

Soil composition.

Soil consists of solid, liquid, gaseous and living parts. Their ratio is not the same not only in different soils, but also in different horizons of the same soil. A decrease in the content of organic substances and living organisms from the upper soil horizons to the lower and an increase in the intensity of transformation of the components of the parent rock from the lower horizons to the upper ones is natural.

The solid part of the soil is dominated by mineral substances of lithogenic origin. These are fragments and particles of primary minerals of various sizes (quartz, feldspars, hornblendes, mica, etc.), formed in the process of weathering of secondary minerals (hydromica, montmorillonite, kaolinite, etc.) and rocks. The sizes of these fragments and particles are varied - from 0.0001 mm to several tens of cm. This variety of sizes determines the looseness of the soil structure. The bulk of the soil is usually fine earth - particles with a diameter of less than 1 mm.

The mineralogical composition of the solid part of the soil largely determines its fertility. The composition of mineral substances includes: Si, Al, Fe, K, Mg, Ca, C, N, P, S, much less trace elements: Cu, Mo, I, B, F, Pb, etc. The vast majority of elements are in oxidized form. In many soils, mainly in soils of insufficiently moistened territories, there is a significant amount of calcium carbonate CaCO 3 (especially if the soil was formed on a carbonate rock), in soils of arid regions - CaSO 4 and other more readily soluble salts (chlorites); the soils of humid tropical regions are enriched in Fe and Al. However, the implementation of these general laws depends on the composition of the parent rocks, soil age, topography, climate, etc.

The composition of the solid part of the soil also includes organic matter. There are two groups of organic substances in the soil: those that have entered the soil in the form of plant and animal residues and new, specific humic substances arising from the transformation of these residues. There are gradual transitions between these groups of soil organic matter, in accordance with this, the organic compounds contained in the soil are also divided into two groups.

The first group includes compounds contained in large quantities in plant and animal residues, as well as compounds that are products of the vital activity of plants, animals and microorganisms. These are proteins, carbohydrates, organic acids, fats, lignin, resins, etc. These compounds in total make up only 10-15% of the total mass of soil organic matter.

The second group of soil organic compounds is represented by a complex complex of humic substances, or humus, which arose as a result of complex biochemical reactions from compounds of the first group. Humic substances make up 85–90% of the organic part of the soil, they are represented by complex high-molecular compounds of an acidic nature. The main groups of humic substances are humic acids and fulvic acids. . In the elemental composition of humic substances, carbon, oxygen, hydrogen, nitrogen and phosphorus play an important role. The humus contains the main elements of plant nutrition, which, under the influence of microorganisms, become available to plants. The humus content in the upper horizon of different soil types varies widely: from 1% in gray-brown desert soils to 12-15% in chernozems. Different types of soils differ in the nature of the change in the amount of humus with depth.

The soil also contains intermediate decomposition products of organic compounds of the first group.

When organic matter decomposes in the soil, the nitrogen contained in them is converted into forms available to plants. Under natural conditions, they are the main source of nitrogen nutrition for plant organisms. Many organic substances are involved in the creation of organo-mineral structural units (lumps). The resulting structure of the soil largely determines its physical properties, as well as water, air and thermal conditions.

The liquid part of the soil or, as it is also called, the soil solution Is the water contained in the soil with dissolved gases, minerals and organic substances that have entered it when passing through the atmosphere and percolating through the soil mass. The composition of soil moisture is determined by the processes of soil formation, vegetation, general characteristics of the climate, as well as the season, weather, human activities (fertilization, etc.).

Soil solution plays a huge role in soil formation and plant nutrition. The main chemical and biological processes in the soil can only take place in the presence of free water. Soil water is the environment in which the migration of chemical elements occurs in the process of soil formation, the supply of plants with water and dissolved nutrients.

In non-saline soils, the concentration of substances in the soil solution is low (usually does not exceed 0.1%), and in saline soils (salt marshes and solonetzes), it is sharply increased (up to as many as tens of percent). The high content of substances in soil moisture is harmful to plants, because this makes it difficult for them to receive water and nutrients, causing physiological dryness.

The reaction of the soil solution in soils of different types is not the same: acidic reaction (pH 7) - soda salt licks, neutral or slightly alkaline (pH = 7) - ordinary chernozems, meadow and brown soils. Too acidic and too alkaline soil solution negatively affects the growth and development of plants.

The gaseous part, or soil air, fills the pores of the soil not occupied by water. The total volume of soil pores (porosity) is from 25 to 60% of the soil volume ( cm... Morphological characteristics of soils). The ratio between soil air and water is determined by the degree of soil moisture.

The composition of soil air, which includes N 2, O 2, CO 2, volatile organic compounds, water vapor, etc., differs significantly from atmospheric air and is determined by the nature of many chemical, biochemical, and biological processes occurring in the soil. The composition of soil air is not constant, depending on external conditions and the season, it can change significantly. For example, the amount of carbon dioxide (CO 2) in the soil air changes significantly in the annual and daily cycles due to the different rates of gas emission by microorganisms and plant roots.

Constant gas exchange takes place between soil and atmospheric air. Root systems of higher plants and aerobic microorganisms vigorously absorb oxygen and release carbon dioxide. Excess CO 2 from the soil is released into the atmosphere, and the atmospheric air enriched with oxygen penetrates into the soil. Gas exchange of the soil with the atmosphere can be hindered either by the dense composition of the soil, or by its excessive moisture. In this case, the oxygen content in the soil air sharply decreases, and anaerobic microbiological processes begin to develop, leading to the formation of methane, hydrogen sulfide, ammonia and some other gases.

Oxygen in the soil is necessary for the respiration of plant roots, therefore, the normal development of plants is possible only under conditions of sufficient air access to the soil. With insufficient oxygen penetration into the soil, plants are inhibited, slow down their growth, and sometimes completely die.

Oxygen in the soil is also of great importance for the life of soil microorganisms, most of which are aerobes. In the absence of air access, the activity of aerobic bacteria stops, and in this regard, the formation of nutrients necessary for plants in the soil also stops. In addition, under anaerobic conditions, processes occur that lead to the accumulation of compounds harmful to plants in the soil.

Sometimes, some gases may be present in the soil air, penetrating through the strata of rocks from places of their accumulation; this is the basis for special gas geochemical methods of prospecting for mineral deposits.

The living part of the soil consists of soil microorganisms and soil animals. The active role of living organisms in the formation of soil determines its belonging to bioinert natural bodies - the most important components of the biosphere.

Water and thermal regimes of the soil.

The water regime of the soil is a combination of all the phenomena that determine the intake, movement, consumption and use of soil moisture by plants. Soil water regime – the most important factor in soil formation and soil fertility.

Precipitation is the main source of soil water. A certain amount of water enters the soil as a result of condensation of steam from the air, sometimes nearby groundwater plays a significant role. In areas of irrigated agriculture, irrigation is of great importance.

Water consumption is as follows. Part of the water entering the soil surface flows off in the form of surface runoff. The largest amount of moisture that has entered the soil is absorbed by plants, which then partially evaporate it. Some water is consumed for evaporation , moreover, part of this moisture is retained by the vegetation cover and evaporates from its surface into the atmosphere, and part evaporates directly from the soil surface. Soil water can also be consumed in the form of subsurface runoff - a temporarily existing phenomenon that occurs during periods of seasonal soil moisture. At this time, gravity water begins to move along the most permeable soil horizon, the aquiclude for which is the less permeable horizon. Such seasonally existing waters are called Finally, a significant part of the soil water can reach the surface of the groundwater, the outflow of which takes place through a waterproof bed-aquiclude, and leave in the composition of the groundwater runoff.

Atmospheric precipitation, melt and irrigation water penetrate into the soil due to its permeability (ability to pass water). The more large (non-capillary) intervals in the soil, the higher its water permeability. Of particular importance is water permeability for the absorption of melt water. If in the fall the soil is frozen in a highly moistened state, then usually its permeability to water is extremely insignificant. Under forest vegetation, which protects the soil from severe freezing, or in fields with early snow retention, melt water is well absorbed.

Technological processes during soil cultivation, the supply of water to plants, physicochemical and microbiological processes that determine the transformation of nutrients in the soil and their supply with water to the plant depend on the water content in the soil. Therefore, one of the main tasks of agriculture is to create a water regime in the soil that is favorable for cultivated plants, which is achieved by the accumulation, conservation, rational use of soil moisture, and, if necessary, by irrigation or drainage of land.

The water regime of the soil depends on the properties of the soil itself, climate and weather conditions, the nature of natural plant formations, on cultivated soils - on the characteristics of cultivated plants and their cultivation technique.

The following main types of soil water regime are distinguished: leaching, non-leaching, effusion, stagnant and permafrost (cryogenic).

Pririmyvny In the type of water regime, the entire soil layer is annually soaked to groundwater, while the soil returns to the atmosphere less moisture than it receives (excess moisture seeps into the groundwater). Under the conditions of this regime, the soil-subsoil stratum is, as it were, washed out by gravitational water every year. The flushed type of water regime is typical for humid temperate and tropical climates, where the amount of precipitation is greater than evaporation.

The non-flushing type of water regime is characterized by the absence of continuous soaking of the soil mass. Atmospheric moisture penetrates into the soil to a depth of several decimeters to several meters (usually no more than 4 m), and between the wetted soil layer and the upper boundary of the capillary border of groundwater there is a horizon with constant low moisture (close to wilting moisture), called the dead horizon of desiccation ... This mode differs in that the amount of moisture returned to the atmosphere is approximately equal to its intake with precipitation. This type of water regime is typical for a dry climate, where the amount of precipitation is always significantly less than evaporation (a conventional value characterizing the maximum possible evaporation in a given area with an unlimited supply of water). For example, it is typical for steppes and semi-deserts.

Effusion the type of water regime is observed in a dry climate with a sharp predominance of evaporation over precipitation, in soils that feed not only on precipitation, but also on the moisture of shallow groundwater. In an effusion-type water regime, groundwater reaches the soil surface and evaporates, which often leads to land salinization.

The stagnant type of water regime is formed under the influence of the close occurrence of groundwater in a humid climate, in which the amount of atmospheric precipitation exceeds the amount of evaporation and absorption of water by plants. Due to excessive moisture, a perch is formed, as a result of which waterlogging of the soil occurs. This type of water regime is typical for depressions in the relief.

Permafrost (cryogenic) type of water regime is formed on the territory of continuous permafrost. Its peculiarity is the presence at a shallow depth of a constantly frozen water-resistant horizon. As a result, despite the small amount of precipitation, the soil is oversaturated with water in the warm season.

The thermal regime of the soil is the sum of the phenomena of heat exchange in the system of the surface layer of air - soil - parent rock; its characteristics also include the processes of transfer and accumulation of heat in the soil.

The main source of heat entering the soil is solar radiation. The thermal regime of the soil is determined mainly by the ratio between the absorbed solar radiation and the thermal radiation of the soil. The features of this ratio determine the differences in the regime of different soils. The thermal regime of the soil is formed mainly under the influence of climatic conditions, however, it is also influenced by the thermophysical properties of the soil and its underlying rocks (for example, the intensity of absorption of solar energy depends on the color of the soil, the darker the soil, the greater the amount of solar radiation it absorbs) ... Permafrost has a special effect on the thermal regime of the soil.

The thermal energy of the soil is involved in the phase transitions of soil moisture, being released during ice formation and condensation of soil moisture and wasted during ice melting and evaporation.

The thermal regime of the soil has a secular, long-term, annual and daily cyclicity associated with the cyclicity of the solar radiation energy entering the earth's surface. On average, long-term terms, the annual heat balance of a given soil is equal to zero.

Daily fluctuations in soil temperature cover the soil thickness from 20 cm to 1 m, annual - up to 10-20 m. Soil freezing depends on the climatic characteristics of the site, the freezing temperature of the soil solution, the thickness of the snow cover and the time of its fall (since the snow cover reduces cooling the soil). The depth of soil freezing rarely exceeds 1–2 m.

Vegetation has a significant effect on the thermal regime of the soil. It traps solar radiation, as a result of which the soil temperature in summer can be lower than the air temperature. Forest vegetation has a particularly noticeable effect on the thermal regime of soils.

The thermal regime of the soil largely determines the intensity of mechanical, geochemical and biological processes in the soil. For example, the intensity of the biochemical activity of bacteria increases with an increase in soil temperature to 40–50 ° C; above this temperature, the vital activity of microorganisms is inhibited. At temperatures below 0 ° C, biological phenomena are abruptly inhibited and stopped. The thermal regime of the soil has a direct impact on the growth and development of plants. An important indicator of the supply of plants with soil heat is the sum of active soil temperatures (i.e. temperatures above 10 ° C, at these temperatures active vegetation of plants takes place) at a depth of the arable layer (20 cm).

Morphological characteristics of soils.

Like any natural body, the soil has a sum of external, so-called morphological features, which are the result of the processes of its formation and therefore reflect the origin (genesis) of soils, the history of their development, their physical and chemical properties. The main morphological features of the soil are: soil profile, color and color of soils, soil structure, granulometric (mechanical) composition of soils, soil composition, new formations and inclusions.

Soil classification.

Each science, as a rule, has a classification of the object of its study, and this classification reflects the level of development of science. Since science is developing all the time, the classification is being improved accordingly.

In the pre-Dodokuchaev period, they studied not the soil (in the modern view), but only its individual properties and aspects, therefore, the soil was classified according to its individual properties - chemical composition, particle size distribution, etc.

Dokuchaev showed that the soil is a special natural body, which is formed as a result of the interaction of soil formation factors, and established the characteristic features of soil morphology (first of all, the structure of the soil profile) - this gave him the opportunity to develop a soil classification on a completely different basis than was done previously.

Dokuchaev took genetic soil types formed by a certain combination of soil formation factors as the main classification unit. This genetic classification of soils is based on the structure of the soil profile, which reflects the process of soil development and their regimes. The modern soil classification used in our country is a developed and supplemented classification by Dokuchaev.

Dokuchaev identified 10 soil types, and in the updated modern classifications there are more than 100.

According to the modern classification used in Russia, soils with a single profile structure, with a qualitatively similar process of soil formation, which develops under conditions of the same thermal and water regimes, on parent rocks of a similar composition and under the same type of vegetation, are combined into one genetic type. Depending on the moisture content, the soils are combined into rows. Rows of automorphic soils are distinguished (i.e., soils that receive moisture only due to atmospheric precipitation and on which groundwater does not have a significant effect), hydromorphic soils (i.e. soils that are significantly affected by groundwater) and transitional automorphic soils. -hydromorphic soils.

Genetic soil types are subdivided into subtypes, genera, species, varieties, categories, and they are combined into classes, series, formations, generations, families, associations, etc.

The genetic classification of soils developed in Russia for the First International Soil Congress (1927) was adopted by all national schools and contributed to the elucidation of the main laws of soil geography.

Currently, a unified international soil classification has not been developed. A significant number of national soil classifications have been created, some of them (Russia, USA, France) include all the soils of the world.

The second approach to soil classification was developed in 1960 in the United States. The American classification is not based on an assessment of the conditions of formation and the associated genetic characteristics of various soil types, but on the basis of easily detectable morphological characteristics of soils, primarily on the study of certain horizons of the soil profile. These horizons were called diagnostic .

The diagnostic approach to soil taxonomy turned out to be very convenient for compiling detailed large-scale maps of small areas, but such maps practically could not be compared with survey small-scale maps based on the principle of geographic and genetic classification.

Meanwhile, by the early 1960s, it became clear that a global soil map was needed to define a strategy for agricultural food production, the legend of which should be based on a classification that eliminated the gap between large and small-scale maps.

Experts from the United Nations Food and Agriculture Organization (FAO), together with the United Nations Educational, Scientific and Cultural Organization (UNESCO), have begun to create an International Soil Map of the World. Work on the map lasted more than 20 years and more than 300 soil scientists from different countries took part in it. The map was created through discussions and agreements between various national scientific schools. As a result, a map legend was developed, which was based on a diagnostic approach to the definition of classification units of all levels, although it also took into account certain elements of the geographic-genetic approach. The publication of all 19 sheets of the map was completed in 1981, since then new data have been obtained, certain concepts and formulations in the map legend have been clarified.

Basic laws of soil geography.

The study of the regularities of the spatial distribution of different types of soils is one of the fundamental problems of earth sciences.

Revealing the regularities of soil geography became possible only on the basis of V.V. Dokuchaev's concept of soil as a result of the interaction of soil formation factors, i.e. from the standpoint of genetic soil science. The following basic patterns were identified:

Horizontal soil zoning. In large flat areas, soil types arising under the influence of soil formation conditions typical for a given climate (i.e., automorphic soil types developing on watersheds, provided that atmospheric precipitation is the main source of moisture), are located in vast stripes - zones elongated along strips with close atmospheric humidification (in areas with insufficient moisture) and with the same annual sum of temperatures (in areas with sufficient and excessive moisture). Dokuchaev called these types of soils zonal.

This creates the main regularity of the spatial distribution of soils in flat areas - horizontal soil zoning. Horizontal soil zoning does not have a planetary distribution; it is typical only for very extensive flat areas, for example, the East European Plain, parts of Africa, the northern half of North America, Western Siberia, and the flat areas of Kazakhstan and Central Asia. As a rule, these horizontal soil zones are located latitudinal (i.e., extended along the parallels), but in some cases, the direction of the horizontal zones changes sharply under the influence of the relief. For example, the soil zones of western Australia and the southern half of North America stretch along the meridians.

The discovery of horizontal soil zoning was made by Dokuchaev based on the theory of soil formation factors. This was an important scientific discovery, on the basis of which the doctrine of natural zones was created. .

The following main natural zones replace each other from the poles to the equator: polar zone (or zone of arctic and Antarctic deserts), tundra zone, forest-tundra zone, taiga zone, mixed forest zone, deciduous forest zone, forest-steppe zone, steppe zone, semi-desert zone, zone deserts, a zone of savannas and woodlands, a zone of variable wet (including monsoon) forests and a zone of moist evergreen forests. Each of these natural zones is characterized by completely specific types of automorphic soils. For example, on the East European Plain, latitudinal zones of tundra soils, podzolic soils, gray forest soils, chernozems, chestnut soils, and brown desert-steppe soils are clearly expressed.

Areas of subtypes of zonal soils are also located within zones in parallel stripes, which makes it possible to distinguish soil subzones. So, the zone of chernozems is subdivided into subzones of leached, typical, ordinary and southern chernozems, the zone of chestnut soils - into dark chestnut, chestnut and light chestnut.

However, the manifestation of zoning is characteristic not only of automorphic soils. It was found that certain zones correspond to certain hydromorphic soils (i.e. soils, the formation of which occurs under a significant influence of groundwater). Hydromorphic soils are not azonal, but their zoning is manifested differently than in automorphic soils. Hydromorphic soils develop next to automorphic soils and are geochemically related to them; therefore, the soil zone can be defined as the territory of distribution of a certain type of automorphic soils and hydromorphic soils in geochemical conjugation with them, which occupy a significant area - up to 20-25% of the area of ​​soil zones.

Vertical soil zoning. The second regularity of soil geography is vertical zoning, which manifests itself in the change of soil types from the foot of the mountain system to its peaks. With the height of the terrain it becomes colder, which entails regular changes in climatic conditions, flora and fauna. Soil types change accordingly. In mountains with insufficient moisture, the change in vertical belts is determined by a change in the degree of moisture, as well as the exposure of slopes (the soil cover here acquires an exposure-differentiated character), and in mountains with sufficient and excessive moisture, it is due to a change in temperature conditions.

At first, it was believed that the change of vertical soil zones is completely analogous to the horizontal zonation of soils from the equator to the poles, but later it was found that among mountain soils, along with types common both on plains and in mountains, there are soils formed only in mountainous conditions. landscapes. It was also found that a strict sequence of vertical soil zones (belts) is very rarely observed. Separate vertical soil belts fall out, mix, and sometimes even change places, so it was concluded that the structure of the vertical zones (belts) of a mountainous country is determined by local conditions.

The phenomenon of facies. I.P. Gerasimov and other scientists have found that the manifestation of horizontal zoning is corrected by the conditions of specific regions. Depending on the influence of oceanic basins, continental spaces, large mountain barriers on the path of air masses movement, local (facies) climatic features are formed. This is manifested in the formation of the peculiarities of local soils up to the appearance of special types, as well as in the complication of horizontal soil zoning. Due to the phenomenon of facies, even within the distribution of one soil type, the soil can have significant differences.

Intrazonal soil subdivisions are called soil provinces . A soil province is understood as a part of a soil zone that is distinguished by the specific features of soil subtypes and types and by the conditions of soil formation. Similar provinces of several zones and subzones are combined into facies.

Mosaicity of the soil cover. In the process of detailed soil-survey and soil-cartographic work, it was found that the idea of ​​the homogeneity of the soil cover, i.e. the existence of soil zones, subzones, and provinces is very conditional and corresponds only to the small-scale level of soil research. In fact, under the influence of meso- and micro-relief, variability of the composition of soil-forming rocks and vegetation, and the depth of groundwater, the soil cover within zones, subzones and provinces is a complex mosaic. This soil mosaic consists of different degrees of genetically related soil areas, which form a certain pattern of the soil cover and create its structure, all the components of which can only be shown on large-scale or detailed soil maps.

Natalia Novoselova

Literature:

Williams V.R. Soil science, 1949
Soils of the USSR... M., Thought, 1979
Glazovskaya M.A., Gennadiev A.N. , M., Moscow State University, 1995
Maksakovsky V.P. Geographic picture of the world... Part I. General characteristics of the world. Yaroslavl, Verkhne-Volzhsky book publishing house, 1995
Workshop on General Soil Science... Moscow State University Publishing House, Moscow, 1995
Dobrovolsky V.V. Soil geography with the basics of soil science... M., Vlados, 2001
Zavarzin G.A. Lectures on natural history microbiology... M., Science, 2003
Eastern European forests. Holocene history and modern times... Book 1. Moscow, Nauka, 2004



Climatic conditions in different regions of the world vary considerably. As a result of these differences, various types of soils were formed, each of which has its own agrotechnical characteristics.

Soil structure, fertility and origins determine the basic characteristics that make it possible to organize soil classification.

In the classification of soils, it is customary to distinguish several nested structural units: type, subtype, genus, species, variety and category.

Soil types and their characteristics.

The main soil types are represented by the following variations:

• Soils of the tundra zone.
• Soils of the taiga-forest zone.
• Soils of the forest-steppe zone.
• Soils of the steppe zone.
• Soils of the dry steppe zone.
• Soils of the semi-desert zone.
• Soils of dry subtropics.
• Soils of humid subtropics.
• Intrazonal soils.
• Soils of river floodplains.

What are the characteristics and features of the main soil types?

1) Soils of the tundra zone.

The main type of soil in this climatic zone is tundra-gley. Formed in low temperatures, with little precipitation. Moisture evaporation is negligible due to low temperatures. Because of this, there is an excess of water on the soil surface.

The depth of soil warming is low, as a result, soil formation processes take place only in the upper layers of the soil, and permafrost is located at a greater depth.

Vegetation is poorly developed on tundra-gley soils. These are mainly dwarf shrubs and trees, lichens, mosses. Some types of cereals are present. There are no forests in the tundra zone, which is hidden in the very word "tundra" - in the translation "treeless".

Excessive moisture content in tundra-gley soils in combination with low temperatures has a depressing effect on the vital activity of microorganisms. The humus layer is thin; over time, peat accumulates.

2) Soils of the taiga-forest zone.

There are podzolic, sod-podzolic and gley-podzolic soils.

The climate is moderately humid and cold. A large number of forests and swamps. The soils are mostly acidic with high humidity. The humus content is low.

3) Soils of the forest-steppe zone.

They are subdivided into gray forest, brown forest, podzolized and leached chernozems.

The climate is moderately humid and moderately warm. The amount of precipitation is insignificant. Forests alternate with steppe expanses. The humus content is quite high, the soils have good fertility.

4) Soils of the steppe zone.

The traditional soils for this zone are chernozems.

The climate is characterized by warm summers and not very cold winters. The rate of precipitation is average. Most of the territories are plains.

The humus horizon has an impressive depth, but a good supply of moisture to the soil is required to achieve high yields.

5) Soils of the dry steppe zone.

The main soils of dry steppes are chestnut.

The climate is arid with low rainfall. The relief structure is flat.

6) Soils of the semi-desert zone.

Represented by brown arid soils.

The climate is very dry with little rainfall. The relief mainly consists of plains, there are mountains.

7) Soils of dry subtropics.

Traditional soils are gray soils.

The climate is dry and hot. The relief is represented by plains and foothills.

8) Soils of humid subtropics.

For this zone, the most common soils are red soils. The climate is warm, with high humidity and high rainfall, the temperature is stable throughout the year.

The relief is low mountains and foothills.

The amount of humus is not very large. The soil is often deficient in phosphorus and nitrogen.

9) Intrazonal soils.

Usually the climate is arid and very warm, and the relief is flat.

The fertility level is very low.

10) Soils of river floodplains.

A feature of floodplain soils is that they are often flooded when nearby rivers flood. There are alluvial (floodplain) sod, bog and meadow soils.

The main types of soils in Russia.

On the territory of Russia, the most common soils are:

• Soils of the tundra zone.
• Soils of the taiga-forest zone.
• Soils of the forest-steppe zone.
• Soils of the steppe zone.
• Soils of the dry steppe zone.
• Soils of the semi-desert zone.

Soil

The Russian Federation is characterized by a wide variety of bioclimatic conditions, which determines the diversity of soils on its territory. In addition to differences in the specifics of the climate and modern ecosystems, the diversity of soils in Russia is determined by the complexity of the geological structure and history of the upper sediment cover on the earth's surface. As a rule, each type of natural biogeocenoses corresponds to a certain type or group of soil types. Together with the climatic parameters of the soil, they determine the nature of land use in agriculture. The geographic distribution of soils is governed by the laws of soil geography, primarily latitudinal zoning and vertical zoning. Below is a description of the soils of the main natural zones of Russia.

Soils of the arctic zone. The Arctic zone occupies a relatively small territory in Russia: it is distributed on the islands of the Arctic Ocean, such as Franz Josef Land, Novaya Zemlya, Severnaya Zemlya, the northern part of the Novosibirsk Islands, as well as on the northern tip of the Taimyr Peninsula (Cape Chelyuskin). In the Arctic zone, soils occupy only ice-free places where lichens and mosses grow, and in some places - clumps of cereals. They thaw for 2–3 months a year to a depth of 20–30 cm. The granulometric composition of these soils is dominated by gravelly and coarse sandy fractions. The content of organic carbon in soils does not exceed 1.0–1.5% in the surface horizon, the reaction of the environment is close to neutral. The soils that form on the coasts of the ocean are characterized by the accumulation of salts, in some places salt efflorescence on the surface.

Tundra and forest-tundra soils. The tundra zone stretches along the coast of the Arctic Ocean throughout the Russian North. It is characterized by milder climatic conditions than the Arctic zone and a relatively continuous soil and vegetation cover, which is absent only on rock outcrops (so-called rocks) and on glaciers.

The tundra is subdivided into three subzones: arctic tundra, typical (lichen-moss) tundra, and southern (shrub) tundra.

The Arctic tundra occupies a narrow strip along the ocean coast immediately south of the Arctic zone. Typical landscapes are spotty fractured-polygonal tundras, where spots devoid of soil and vegetation cover can occupy up to 40–80% of the total area. The main areas are occupied by the so-called. arct-tundra soils. They are formed under shrub-herb-lichen-moss vegetation on loamy and clayey sediments of different genesis and have a thin (3–6 cm) humus-accumulative horizon, under which lies a brown-colored middle horizon with bluish spots. This color diagnoses gleying - the process of iron and manganese reduction under conditions of oxygen deficiency due to prolonged saturation of the soil with moisture. For many soils of this zone, cryoturbation is typical in their profile - signs of soil mixing as a result of its freezing and thawing. The soils are characterized by a relatively high content of organic carbon in the surface horizon (2.0–3.5%) and its deep penetration into the soil layer, the reaction of the environment - neutral or close to neutral, a high content of exchange bases, among which calcium predominates.

Typical tundra occupies vast areas in the north of the country, especially in its Asian part, and is characterized by more diverse and developed soils than the arctic tundra. A significant part of the soil cover is made up of tundra gley soils (see Gleezems), which differ from arct-tundra soils by a deeper profile, thawing up to 40–100 cm, and a more vivid manifestation of gleying, which indicates prolonged waterlogging. For the tundra soils of the European part of Russia, surface gleying is characteristic, and for the soils of Eastern Siberia, suprapermafrost. In contrast to the soils of the arctic tundra, the tundra gley soils of the typical tundra are characterized by an acidic reaction of the medium in the upper horizon, which is replaced by a slightly acidic one with depth. In addition to tundra gley soils, tundra bog soils and podburs occupy large areas in this zone. Tundra bog soils are formed on low, poorly drained relief elements. They are characterized by a constant stagnant water regime and slow decomposition of plant residues, which leads to the formation of peat on the soil surface; the thickness of the peat deposit in the tundra, as a rule, is insignificant due to the low biological productivity of tundra ecosystems. On gravelly and sandy rocks with good water permeability, podburs are formed - acidic, without signs of gleying, soils with a rusty-brown horizon under moss and shrub vegetation. A common feature of the soil cover of the tundra is its variegation and complexity, that is, the frequent alternation of small patches of different soils and bare areas devoid of vegetation, which is associated with severe climatic conditions. The fertility of the tundra soils is low, but the mosses and lichens growing on them serve as food for the reindeer.

The southern shrub tundra, turning to the forest tundra to the south, is characterized by widespread shrub thickets in the river valleys. In the European part of Russia, these thickets consist of polar willow, bushy alder, and in the Far East, they are represented mainly by dwarf pine. The soils of the southern tundra are generally similar to the soils of a typical tundra, but the thickness of the active layer and, accordingly, the thickness of the soil profile is greater here.

The forest-tundra, which receives more heat than the more northern zones, is characterized by the penetration of sparse and oppressed forest stands into the treeless tundra space. This leads to the formation of gley-podzolic soils under these conditions, which prevail in the soil cover of the northern taiga. In these soils, against the background of gleying, thin clay particles are also removed from the upper soil horizons down the profile. Podburs and dwarf podzols prevail on rocks of light grain-size composition.

Soils of the taiga-forest zone. Traditionally in Russia, the taiga zone is subdivided into northern, middle and southern taiga.

This is true for most of the territory of Russia, except for Western Siberia, where a clear border between the northern and middle taiga is not observed both in geobotanical and soil terms. The soil cover varies greatly in the European and Asian parts of the country.

The taiga of the European territory of Russia is characterized by the formation of podzolic soils, in which the removal of silty material from the upper horizons to the middle horizons of the soil occurs. Due to this process, a bleached horizon with a light grain size distribution is formed in the upper part of the profile. The middle horizon (horizon B) is enriched with clayey material, which forms films and incrustations on soil aggregates and in pores. The clay-enriched (textural) horizon is characterized by yellowish-brown or reddish-brown colors, compaction and a well-defined prismatic structure.

In the northern taiga, with a small amount of solar heat and excessive moisture, gleying is observed in the profiles of gley-podzolic soils formed here, associated with stagnation of moisture in the upper horizons. The soil cover also contains peat bog and gley soils. Taiga gley soils are represented by rather diverse soils, the common feature of which is either gleying of the entire profile, or the presence of a pronounced gley horizon lying directly under the peat forest floor or peat surface horizon. Mineral horizons of gleyzems on loamy rocks are usually structureless, waterlogged, with clear signs of permafrost deformations of the soil profile. On sandy and gravelly rocks, illuvial-humus and humus-ferruginous podzols are widespread. Their feature is the presence of a clearly defined bleached podzolic horizon and a dark or rusty-brown humus-ferruginous horizon underneath. Although podzolic soils and podzols have features of similarity and therefore were previously included in one type, these two groups of soils differ significantly both in the processes that form them, and in properties and use.

For vast areas of the middle taiga, podzolic soils are most typical. They form here under spruce, spruce-fir and mixed spruce-birch forests on loamy deposits. Due to the insignificant participation of herbaceous vegetation in the ground cover of middle taiga forests, typical podzolic soils lack sod and humus horizon. Directly under the forest litter lies a light, slightly colored so-called. acidic podzolic horizon with streaming humus.

Soddy-podzolic soils prevail in the soil cover of south-taiga mixed coniferous-deciduous forests, in the profile of which there is both a humus-accumulative and a clarified podzolic horizon (see in the article Podzolic soils). On loamy rocks, they contain 3-5% humus(its content rapidly decreases with depth). These soils are characterized by an acidic reaction of the soil solution, while the acidity is maximum in the forest litter and in the upper mineral horizons of the soil.

Sod-podzolic soils constitute the main fund of arable land in non-chernozem areas and, with an appropriate fertilization system, are successfully used in agriculture to grow a variety of grain, vegetables, fruit and berry and fodder crops.

Podzolic soils are common in a number of regions of Siberia, but in general these soils are not predominant in the taiga of the Asian part of Russia. In Central and Eastern Siberia, taiga permafrost soils (cryozems) are widespread, the profile of which consists of peat forest litter, a thin humus or coarse humus horizon, which turns into a grayish-brown horizon mixed as a result of freezing and thawing; the lower part of the soil profile is saturated with moisture, in a wet state it is thixotropic, that is, it liquefies under mechanical action, structureless. The depth of summer thawing does not exceed 1 m. The permafrost-taiga pale-pale soils of the Central Yakutsk lowland in Yakutia are peculiar. Here they occupy large areas under larch forests and are characterized by a poorly differentiated soil profile. Under the upper humus horizon, there is a light, yellowish-brown horizon, gradually transforming into a loess-like carbonate loam. The reaction of soils is neutral or slightly acidic in the upper horizons and slightly alkaline in the lower ones. With proper reclamation and fertilization, they are suitable for growing grains, vegetables and herbs.

On rich in mineralogical composition of sandy rocks in well-drained conditions, taiga podburs are formed without signs of gleying and podzolization. They are distinguished by the presence of a peat forest floor, directly under which lies a brown illuvial-ferruginous-humus horizon, which gradually turns into the parent rock. There is no clarified podzolic horizon in their profile.

In the Middle Urals, in the foothills of the Altai and Sayan Mountains, in the Far East, under south-taiga, partly and middle-taiga forests, peculiar brown-taiga soils are widespread. The profile of these soils is poorly differentiated into genetic horizons. They are distinguished by a high content of humus (up to 7–15%) and mobile iron compounds in the upper horizon, and an acidic reaction of the soil solution. In landscapes with difficult drainage, contributing to the stagnation of surface waters and the development of the eluvial-gley process, gleyed brown soils are formed.

The volcanic ocher layered ash soils of Kamchatka are even more unique. A characteristic feature of their genesis is the periodic interruption of soil formation by the fallout of new portions of volcanic ash. As a result, their profile consists of superimposed elementary profiles, in each of which the organogenic and middle horizons are distinguished; the latter can be dyed with humus in coffee tones or with iron hydroxides - in ocher. Volcanic soils They are distinguished by light particle size distribution, high water permeability, predominance of weakly crystallized aluminosilicate and ferruginous minerals. The reaction of volcanic ocher soils is acidic, and the absorption capacity of cations is low. Effective use of these soils in forestry.

Swamp soils occupy huge areas in the northern regions of Russia, especially in Western Siberia and the Far East. They are excessively moist throughout the year and therefore are characterized by slow decomposition of plant residues, which leads to the formation of a peat mass.

Peat soils are subdivided according to the thickness of the peat deposit, according to the botanical composition of peat, according to the content of the mineral part (ash part) and according to the degree of decomposition of organic residues. Boggy lowland and raised peat soils are fundamentally different. Low-lying peatlands are formed during flooding with mineralized groundwater, they have a high ash content, peat is composed mainly of sedges and wood, the degree of decomposition of organic residues is high, the reaction of the environment is slightly acidic or neutral. High-moor peat soils are formed when saturated with low-mineralized rainwater: the ash content of peat is low, it is mainly composed of poorly decomposed sphagnum mosses, and the reaction of the medium is acidic.

Boggy lowland soils can be used in agriculture only after drainage reclamation, boggy upland soils are suitable only for forestry. Although the soil types prevailing in the northern and middle taiga zones are practically unsuitable for use in agriculture, their importance is extremely high, since they serve as the basis for the growth and development of forests. Peat-bog soils and peat deposits in these natural zones largely determine the hydrological regime of the northern territories, store huge amounts of carbon and nitrogen stored in the form of organic matter.

On carbonate rocks in Central and Eastern Siberia, soddy-calcareous soils are common (see Rendziny) with a weakly acidic or weakly alkaline reaction, a high humus content (up to 5–12%); they are rich in plant nutrients, but, as a rule, have a low capacity and are leached or podzolized to varying degrees. In the conditions of a humid cool climate in the subzones of the northern and middle taiga, humus-calcareous soils are formed on carbonate rocks, which differ from sod-calcareous soils by an even higher humus content (up to 20% or more).

In floodplains and river deltas under flooded meadows are common alluvial soils formed under conditions of periodic flooding and accumulation of river sediments (alluvium). Vast areas are occupied by alluvial soils along the great rivers of Siberia and the Far East: the Ob, Yenisei, Lena and Amur. They are diverse in mode, structure and properties, depending on the composition of the alluvium, location in one or another area of ​​the river floodplain, as well as on the geographical location of the floodplain itself. In the forest zone, the soils of river floodplains are characterized by an acidic reaction, a relatively high content of organic matter, gleying in the soil profile of a low floodplain, and waterlogging in the near-terrace floodplain.

For deciduous and coniferous-deciduous forests of the south of the Far East, as well as the mountain slopes of the Caucasus, Altai, and Sikhote-Alin, brown soils are characteristic with a weak differentiation of the soil profile and a brown color, which is created due to the accumulation of iron oxides and hydroxides. The reaction is from slightly acidic to neutral. The humus content in the upper, usually well-structured horizon is up to 10% or more. A moderately warm and humid climate determines the richness and diversity of soil biota. Under different conditions of the relief and composition of parent rocks, signs of podzolization or surface gleying appear in brown soils. On leveled, poorly drained areas, podbeaches are found, characterized by a sharp differentiation of the soil profile: under the humus horizon, there is a white or light gray horizon with a lumpy-platy structure and an abundance of ferruginous-manganese concretions.

Almost all soils of the taiga-forest zone are characterized by low natural fertility and require the introduction of organic and mineral fertilizers, including liming to reduce soil acidity. In the northern and middle taiga, the main direction in agriculture is dairy and beef cattle breeding, therefore the soils are used for growing perennial grasses and for pastures. In some places, vegetable growing is developing successfully. In the southern taiga, the use of soil in agriculture is expanding significantly: crops such as rye, oats, barley, and buckwheat are cultivated. The main problems in the development and use of soils in the taiga zone are their acidification in the absence of regular liming, depletion with insufficient fertilization, flooding in case of violation of the hydrology of groundwater, as well as water erosion. Drained peat soils are characterized by accelerated peat drainage.

Gray forest soils are traditionally subdivided into light gray, gray and dark gray forest soils according to an increase in humus content and a decrease in podzolization. The whole type of gray forest soils is characterized by a higher, compared to soddy-podzolic soils, humus content, from 2-3% in light gray to 8% or more in dark gray, and a nutty structure, for which they were previously called walnut soils. Gray, especially dark gray, forest soils are fertile. They grow winter and spring wheat, sugar beets, corn, potatoes, flax, etc. To preserve and increase the fertility of gray forest soils, it is necessary to combat water erosion, grass sowing, the systematic use of organic and mineral fertilizers, taking into account significant differences in the bioclimatic conditions of different provinces and areas of the forest-steppe zone.

In the forest-steppe and steppe natural zones, large areas are occupied by chernozems, deep dark-colored humus soils. Chernozems are characterized by a neutral reaction, a high absorption capacity, and favorable agrophysical properties, which are largely due to the water-resistant lumpy-granular structure of the humified part of the profile. They are very diverse and are subdivided according to the zonal principle into forest-steppe (podzolized, leached, typical) and steppe (ordinary and southern). Typical chernozems are characterized by a dark, almost black color, high, up to 10–12%, humus content, a large thickness of the humus horizon, reaching 80–100 cm and more, a gradual decrease in the amount of humus down the profile and the presence of a horizon with various forms of newly formed calcium carbonates ... Podzolized and leached chernozems form large areas to the north of the typical ones and are distinguished by weak eluvial-illuvial differentiation of the profile in terms of clay content and a decrease in the level of occurrence of the carbonate horizon. The loamy and clayey plains of the steppe zone are dominated by ordinary and southern chernozems with a humus horizon 40–80 cm thick; carbonate new formations are represented by white-eyed - weakly cemented concretions of carbonates in the form of rounded white spots - eyes 1–2 cm in diameter. The humus content is 5–8% in ordinary chernozems and 3–6% in southern chernozems. According to provincial features, i.e., according to the forms of carbonate release, reflecting the water regime, chernozems are divided into micellar-carbonate, cryogenic-micellar, powdery-carbonate, etc.

In the Ciscaucasia, on the Azov-Kuban Plain, ordinary chernozems and southern micellar-carbonate chernozems are widespread. They are distinguished by the large thickness of the humus horizon (up to 120 cm and more), carbonates appear in the upper part of the humus horizon or from the surface. In the steppe Crimea, on loesses, southern and micellar-carbonate chernozems are developed; in the west of the peninsula and at the foothills of the northern slopes of the Crimean mountains, residual carbonate chernozems are widely represented on dense carbonate rocks, and on the Kerch Peninsula, on saline clays, merged chernozems are abundant.

Among the chernozem soils, along low relief elements and with a close occurrence of groundwater (2–5 m), there are meadow-chernozem and chernozem-meadow soils. Meadow chernozem soils are even darker than chernozems; they are distinguished by the greater thickness of the humus layer and the gleyiness of the lower horizons. In contrast, chernozem-meadow soils are characterized by more intense gleying, a higher level of groundwater, and a lower thickness of the humus layer. Meadow chernozem soils are highly fertile, with the exception of saline and solonetzic soils.

The dry steppe zone is dominated by chestnut soils, which contain less humus than chernozems: from 2 to 5%. In addition, they have a lower thickness of the humus horizon (from 15 to 50 cm) and a higher carbonate horizon; gypsum appears at the bottom of the profile. They are often solonetzic and compacted.

Chestnut soils are subdivided into dark chestnut, chestnut, and light chestnut subtypes according to their humus content and a number of other properties, the latter being found mainly in semi-deserts. Large areas of dark chestnut and chestnut soils are plowed up and used for growing grain crops.

Among the chestnut soils along the relief depressions, there are meadow-chestnut soils, which differ from chestnut soils only in greater humus content and better moisture supply. Meadow-chestnut soils most often form complexes with chestnut soils, salt licks and salt marshes.

In the steppe and dry-steppe zones, and to a lesser extent in the forest-steppe, saline soils occupy significant areas, containing readily soluble salts in the surface horizon or throughout the profile; to an even greater extent, salinization processes are manifested in semi-deserts.

The processes of salt accumulation in soils are most pronounced in saline soils. These soils contain more than 1–2% of readily soluble salts in the surface horizon. According to the composition of salts, salt marshes are distinguished chloride, sulfate, soda and mixed (chloride-sulfate, sulfate-chloride, etc.), and according to the composition of cations - sodium, magnesium, calcium.

Agricultural use of salt marshes is possible only under the condition of carrying out radical reclamation, and the most effective is reclamation leaching with the removal of salts from the soil and their removal into the drainage system.

Solonchak soils differ from saline soils by a lower content of readily soluble salts. They are subdivided into highly, medium and slightly salted. Saline soils are adjoined by solonetzes - alkaline soils that do not contain readily soluble salts or do not contain them in the upper horizons, but at a certain depth. The alkaline reaction is due to the high content of exchangeable sodium in the soils. Their upper humus-accumulative horizon is replaced by a columnar, very dense, clay-rich alkaline horizon with alkaline reaction; at the bottom, it passes into the subsolonets walnut horizon with carbonates and gypsum. Solonetzes are widespread mainly in dry semi-desert steppes, as well as in steppe and even forest-steppe zones. Most often they are found in the composition of the so-called. solonetz complexes, including solonchaks, saline, meadow, chestnut soils or chernozems.

Solonets and solonetzic soils are genetically related to malts. They are formed under the influence of stagnant moisture and leaching of salts from the soil profile. Solods are common under birch groves in the forest-steppe of Western Siberia; They are also found in saucer-like depressions in the steppes and forest-steppes. A characteristic feature of malt is a sharp differentiation of the soil profile into genetic horizons with the obligatory inclusion of a light horizon with ferruginous-manganese concretions and the presence of a dense brown-brown illuvial horizon under it. A slightly acidic reaction is characteristic of light solodized horizons, and residual accumulation of silica is also noted in it.

The soils of the forest-steppe, steppe and dry-steppe zones are the basis of the country's soil fund for agricultural needs, which is associated with both optimal climatic conditions and high natural soil fertility. The soils are used for winter and spring wheat, corn, sunflowers, soybeans, vegetables and horticultural crops. The development of chernozems is maximal: almost all soils of the chernozem zone, with the exception of settlements, inconveniences and specially protected areas, are plowed up and used in agriculture. Chestnut soils are also predominantly plowed; partly chestnut soils are used for grazing. In the steppe and dry steppe zones, both chernozems and chestnut soils sometimes require drip irrigation. The development and agricultural use of salt licks is possible, but requires a whole system of reclamation and agrotechnical measures, including gypsum plastering, special deep plowing with subsequent grass sowing.

Semi-desert soils. In Russia, semi-deserts occupy a relatively small area, mainly within the Caspian lowland. There, on ancient alluvial sands and loamy loess-like sediments, brown desert-steppe soils(semi-desert) - low-humus, thin, dense and often solonetzic. The amount of humus in them rarely exceeds 1.5–2.0%, the thickness of the humus horizon is no more than 10–15 cm, below there is a dense brownish-brown horizon, which, in turn, is replaced by an illuvial carbonate horizon; at a depth of 80–100 cm, there are accumulations of gypsum, under which readily soluble salts are found. Along the depressions of the relief, under the herb-grass vegetation, there are meadow-brown soils, which are distinguished by a higher humus content. The soil cover of the semi-desert zone is characterized by variegation with frequent alternation of soils - light chestnut, brown desert-steppe, solonetz and salt marshes.

The soil cover of the semi-desert zone is favorable for the development of pasture animal husbandry, and along depressions with meadow-chestnut and meadow-brown soils - melon growing. When they are irrigated, careful monitoring of the state of soils is necessary in connection with the possible development of their secondary salinization. Overgrazing of livestock leads to rapid degradation of pastures, to desertification and overconsolidation of the upper soil horizons.

Subtropical soils. Subtropical soils are represented on the territory of Russia by yellow soils and brown soils... Zheltozems occupy a narrow strip of land along the Black Sea coast in the Tuapse-Sochi region; they are characterized by an increased content of mobile oxides of iron, aluminum and manganese. Their profile includes a leached yellow horizon with an acidic reaction of the medium, turning downwards into an illuvial light yellow horizon with a large amount of ferruginous-manganese nodules.

Yellow seeds are used for growing tea, citrus fruits, fruit and vegetable crops, but they need organic and mineral fertilizers, as well as protection from water erosion.

Brown soils are common in mountainous Dagestan and in the south of the Crimean Peninsula under dry sparse forests and shrubs with a herbaceous cover in a warm and dry subtropical climate. They distinguish a humus horizon (brownish-gray color of a lumpy-granular structure, contains 4–6% humus), a transitional brown-brown lumpy-nutty clay horizon and a lighter horizon with calcium carbonate release through the pores.

Brown soils are used for orchards and vineyards, they need protection from water erosion.

Mountain soils. Mountain soils occupy more than 1/3 of the total area of ​​the country. These include the soils of the mountainous territories of the Crimea, the Caucasus, the Urals, Altai, Eastern Siberia and the Far East. The soil cover of the mountains is characterized by high complexity. Compared with flat mountain soils, they are characterized by a lower thickness of the vertical profile, good drainage, high gravel and stony. For the soil cover of mountains, an abundance of soils disturbed as a result of slope processes, such as avalanches, landslides, mudflows, surface and gully erosion, is typical. Most mountain soils can be attributed to the corresponding soil types formed on the plains. Some types can be considered specifically mountainous: for example, mountain meadow and mountain meadow steppe soils have no analogues on the plains. Mountain meadow soils are formed in a humid climate under a well-developed herbaceous cover. They have developed sod and humus horizons (the humus content is up to 20%) with a lumpy-granular structure; these soils are characterized by an acidic reaction throughout the profile. Mountain meadow-steppe soils are drier, they have less humus, they are neutral.

Mountain forest soils are of great importance in the country's forestry, as well as in environmental protection. When mountain forests are cut down, their soil cover is rapidly eroded, which entails drifts and pollution of rivers, floods in adjacent territories, and disruption of the hydrological regime in large areas of river basins. Mountain meadow and mountain meadow steppe soils are used in grazing. They need anti-erosion protection.

Anthropogenically transformed and anthropogenic soils. The natural diversity and state of soils are significantly influenced by industrial, mainly agricultural, human activities. The structure, properties, regimes of soils change and are transformed to varying degrees, artificial soils are created, etc. Specialists of the Soil Institute named after V.V.Dokuchaev developed a new classification of soils in Russia (2004), taking into account the degree of their anthropogenic transformation. In this classification, those soils that have been significantly modified by humans, but have not lost the characteristics of the original natural soils, are distinguished as anthropogenically transformed. The name of such soils is formed by adding the “agro-” component to the names of types of natural soils; for example, agropodzolic, agrochernozems, etc. If natural soils are changed so much that they do not retain typical characteristics or are completely created artificially, then they are classified as anthropogenic. This is agrozems(soils completely changed in the process of cultivation), stratozems (bulk soils), etc.

Patterns of soil distribution. In the distribution of soils on the territory of Russia, one can trace geographical patterns associated with the cumulative impact of bioclimatic and geological and geomorphological factors of soil formation. These patterns are reflected in the system of soil-geographic zoning of the Russian Federation (Dobrovolskiy, Urusevskaya, 2006). In accordance with this system, polar, boreal, subboreal and subtropical soil-bioclimatic zones are distinguished on the territory of the country, and within them - soil-bioclimatic regions and facies, soil zones, subzones and provinces. In the direction from north to south, there are zones of arctic and tundra soils, podzolic taiga, gray forest, forest-steppe and steppe chernozems, chestnut dry-steppe, brown semi-desert, subtropical brown and yellow earth soils.

On the territory of Russia, according to the degree of continental climate, 4 soil-bioclimatic facies are clearly distinguished: European moderate continental, West Siberian continental, East Siberian extracontinental and Far Eastern monsoon. The territories of these facies are so different in other natural features, such as relief, parent rocks, and geological history, that they can be considered not only as special bioclimatic facies, but also as special soil-geological countries.

The combination of the influence of bioclimatic and geological and geomorphological factors in each of the identified facies, including segments of latitudinal soil zones, determines the features of the soils and soil cover structures common in them.

The European temperate continental facies is characterized by a clearly pronounced latitudinal zonal soil cover structure; The West Siberian continental facies differs from it in a much wider distribution of gleyed, boggy, peat and peat-gley soils in taiga zones, meadow, meadow chernozem, solonetzic, solodized and saline soils in forest-steppe and steppe zones. The East Siberian extracontinental facies is characterized by the ubiquitous distribution of permanently frozen soils and associated cryogenic processes in soils. The latitudinal zoning of the soil cover is weakly expressed in it. In the conditions of mountainous relief on dense sedimentary and massively crystalline rocks, various gravelly thin tundra and taiga permafrost soils prevail. Non-podzolized soils such as soddy-calcareous, taiga podburs, granuzems with a structure in the form of rounded granules, humified and enriched soils with mobile iron compounds without signs of podzolization are formed on the products of weathering of traps and on carbonate rocks. The Far Eastern monsoon soil-bioclimatic facies is characterized by a wide variety of soils formed under conditions of plain and mountainous soil formation. Due to the meridional elongation of the territory of this facies along the Pacific coast from Chukotka to the south of Primorsky Krai, the latitudinal zoning of soils is clearly expressed, but in the form of relatively small sections of soil-geographical zones of the tundra, northern, middle and southern taiga and coniferous-deciduous forests. A common feature of the soils of the Far Eastern monsoon facies both in the north and in the south is their increased moisture content; therefore, tundra-bog, peat-bog, sod-gley, brown gley soils, podbely, meadow-bog, meadow-chernozem-like (“black earth Amur prairies ") soil.

A unique soil province is the Kamchatka Peninsula, where soil formation is carried out under conditions of active volcanic activity.

Latitudinal bioclimatic zoning manifests itself in the geography of the soil cover not only in the form of flat soil zones, but also in the different structure of the vertical zonation of mountainous countries, depending on their geographic location. For example, the system of vertical zoning of the Northern Urals is represented by only three altitudinal belts: the lower northern taiga dark coniferous with gleypodzolic soils and taiga podburs, the middle belt of tundra-gley and tundra podburs and the upper loach belt of primitive mountain soils and stony placers. In the structure of the vertical zoning of the Middle Urals in the lower zone, under the middle taiga spruce and spruce-fir forests, podzolic soils prevail, on the average - brown taiga; higher up, they are replaced by mountain meadow soils, and then by tundra podburs. The vertical zoning of the Southern Urals is represented by six vertical belts. The lower belt at the southern end of the mountain range is formed by a forest-steppe with gray forest soils, among which leached chernozems appear along intermontane depressions and southern slopes. Above, there is a belt of deciduous forests with gray forest soils, which, as the absolute height and moisture increases, is replaced by a coniferous-broad-leaved belt with brown soil, and then a belt of dark coniferous forests with brown mountain soils; even higher is the belt of mountain meadows with mountain meadow soils. At a height of approx. 1500 m mountain meadows turn into mountain tundra with tundra podburs and tundra peaty-gley soils (see Fig. 1).

The specificity of the vertical zoning of soils in the mountains depends not only on the latitude of the area, but also on the location of the mountain range in relation to the dominant direction of atmospheric circulation, the exposure of slopes, and other factors. So, on the western Black Sea slope of the Greater Caucasus in the Sochi-Tuapse region, the lower mountain belt is represented by a humid-subtropical landscape with yellow-earth soils, passing higher into the belt of deciduous and coniferous-deciduous forests on brown soils. On the eastern part of the slope of the Greater Caucasus to the Caspian Sea, the lower belt is represented by a variety of dry forests and shrubs of the Mediterranean type on mountain-brown soils, even higher - mountain-meadow and mountain-steppe soils. Rice. 2 illustrates the influence of exposure on the structure of the vertical zonation of the Tannu-Ola ridge (Republic of Tyva).

Geological and geomorphological conditions of soil formation are equally important along with the geographical patterns of soil distribution, which are mainly due to bioclimatic factors. They determine the quantitative relationships and spatial arrangement of plain and mountain soils, the isolation of mineralogical and geochemical soil provinces and geological and geomorphological soil districts and regions, the granulometric composition of parent rocks and soils, the formation of special lithogenic soil types. The latter are formed when the parent rocks have a decisive influence on the genesis and properties of soils. These are soddy-calcareous soils (rendzins) found in different bioclimatic zones, ocher volcanic soils formed under the direct impact of volcanic ash.

The characteristics of soils in Russia are given in accordance with the legend of the new Soil Map of Russia (2017, scale 1: 15,000,000).

Lesson objectives:

1. Coordinate the independent work of students, taking into account their personal characteristics, in order to create the most favorable conditions for their manifestation.
2. Think over the main types of communication, forms of cooperation between students and the teacher, taking into account personal interaction, equal partnership in the lesson.
3. In the conditions of student-centered learning, to provide each student, based on his abilities, inclinations, interests, subjective experience, the opportunity to realize himself in the knowledge of the diversity of Russian soils and their dependence on vegetation.

Lesson Objectives:

1. Using the subjective experience of each student about soils, the ability to independently obtain information using maps, to form knowledge about the diversity of soils in Russia.
2. Encourage students to make their own choice and use the methods of in-depth study of the material about the main types of soils in Russia that are most significant for them.
3. Stimulate the student to self-development and self-expression when choosing and performing practical tasks, solving problematic issues.
4. To provide assistance to the creative group in the study of the soils of our area, the impact of economic activities of the population on pollution and soil protection.
5. Conduct reflection, assessment of the acquired knowledge.

Learning new material.

Teacher: Guys, look at the soil map of Russia. What are the main soils moving from north to south.

Teacher: What are the main natural components involved in the formation of soils:

1. Rocks
2. Plants and Animals
3. Climatic conditions
4. Relief
5. Ground water level
6. Permafrost
7. Time

Teacher: Do you think the distribution of soils not only in Russia, but throughout the world is chaotic or obeys the laws of nature?
Students: The distribution of soils obeys the law of latitudinal zoning, in the mountains of altitudinal zonation.
Teacher: Now we will familiarize ourselves with the main types of soils in Russia and try to fill out a table characterizing soils.

The main soils of Russia

Soil types	Conditions of soil formation	Humus content	Soil properties	Natural area
1. Arctic	Little heat and vegetation	No	Not fertile	Arctic
2. Tundra-gley	Permafrost, little heat, waterlogging	1,5%	Low-power, have a gley layer	Tundra
3. Podzolic	To uvl. > 1 Chilly. Plant residues - needles, pepper washout	1,5 – 2%	Washable, sour, infertile.	Taiga
4. Sod-podzolic	To uvl. > 1 More crop residues by flushing the soil in spring	2 – 2,5%	More fertile, sour	Mixed
5. Gray forest, brown forest	To uvl. = 1 Moderate continental climate, remnants of forest and herbaceous vegetation	2 – 5%	Fertile	Broadleaf- war forests
6. Chernozems	To uvl. ? one Lots of heat and plant debris	10 – 12%	Most fertile, grainy	Steppe
7. Chestnut	To uvl. = 0.8, 0.7 A lot of warmth	3 – 5%	Fertile	Dry steppes
8. Brown and gray-brown	To uvl.< 0,5 Dry climate, little vegetation	1%	Salinization of soils	Semi-desert

Arctic soils:

1. Low temperatures all year round.
2. The parent rock is covered with snow or ice.
3. The vegetation cover is represented by mosses and lichens.
4. The process of soil formation is difficult.
5. Arctic soils are formed on small areas of the Arctic islands, not occupied by snow and ice, in the short summer.

Tundra-gley soils:

1. Summer is cold and short.
2. Permafrost.
3. Vegetation cover: mosses, lichens, undersized shrubs.
4. Soil formation slowed down due to lack of heat.
5. Humus contains 1.5%
6. Natural area - tundra.

Podzolic soils:

Summer is cool, K uvl. > 1.

1. Excessive humidification leads to washing out of humus, an infertile leaching layer - podzol - is formed.
2. The vegetation cover is represented by needles.
3. Soil formation is difficult, since the needles contain resins that impede rotting and give increased acidity.
4. Humus - 1.5 - 2%.
5. The natural area is taiga.

Sod-podzolic soils:

Summer is warm, To uvl. > 1.

1. Soil leaching only in spring.
2. The vegetation cover is more varied.
3. The soils are more fertile.
4. Humus - 2%.
5. Natural area - mixed forests.

Gray forest soils:

1. The climate is temperate continental with warm summers. = 1.
2. The vegetation cover is represented by the remains of forest and herbaceous vegetation.
3. The soils are fertile.
4. Humus 2 - 5%.
5. Natural area - deciduous forests.

Chernozem soils:

1. Moderate continental and continental warm climate, K uvl. =< 1; 0,9.
2. The vegetation cover is represented by herbaceous vegetation, there is no leaching, which contributes to the accumulation of humus.
3. The soils are very fertile.
4. Humus - 10 - 12%.
5. The natural zone is the steppe.

Chestnut soils:

1. Continental arid climate, a lot of heat, K uvl.< 1; 0,8.
2. The vegetation cover is represented by herbaceous vegetation, but a lot of heat and little moisture forms a less diverse vegetation cover.
3. The soils are fertile.
4. Humus 3 - 5%.
5. The natural zone is dry steppes.

Brown and gray-brown soils:

1. Sharp continental, dry climate, K uvl.< 0,5.
2. Small vegetation cover.
3. Soil formation is hindered by high temperatures, decreased moisture, and plant litter.
4. Humus - 1%.
5. The soils are saline.
6. Natural area - deserts.

Teacher: You and I have traced the change of soils from north to south on the territory of the Russian Plain. What conclusions can you draw about soil diversity and the main natural components that influence soil formation?

Pupils: There is a latitudinal zoning. As a result of changes in the climatic characteristics of heat and moisture, the vegetation cover changes, and the formation of various soils directly proceeds from the plant litter. Equally bad for the formation of soils is the lack of heat and moisture, as well as their excess. Fertile soils are formed with a sufficient amount of heat and moisture and annual plant litter.

Teacher: What soil is typical for our area?

Pupils: Chernozems.

Teacher: Soil is one of the main treasures of the Belgorod region. The main property of the soil is the presence of humus in it. The region is located in favorable natural and climatic conditions, which contributed to the formation of highly fertile soils. Students of the research group will tell about the soils of our village.

Pupils: The territory of the village of Pushkarnoye is located northwest of the city of Belgorod in the basin of the small rivers Vezelka and Iskrinka, tributaries of the Northern Donets in a pronounced forest-steppe zone. Our steppe spaces are combined with forest tracts, where vegetation of deciduous forests grows.

In forest areas, the soils are gray and dark gray forest soils. On the plains steppe regions - ordinary chernozems. In the river valleys there are chernozem-meadow and floodplain soils.

The acidity of soils in the northwestern part of the Pushkar fields is increased, liming is required.

The duration of the agricultural development of the territory affects the fertility and humus reserves in soils. Man, through his activities, negatively affects the soil. On the territory of our village, the relief is very difficult, there are few flat places, so plowing should be carried out across the slopes, there are many ravines, which also complicates the work in the fields. Water erosion prevails, and the washout of the humus layer from the fields. The ecological detachment of our class is fighting spontaneous dumps in the territory of the village. The floodplain part of the Vezelka River, as well as the river itself, from household waste, was taken under our protection. People in their gardens continue to burn fires, plant remains in spring and autumn, not realizing that this is a valuable raw material that increases soil fertility and fires burn microorganisms present in the soil.

Teacher: Soil is a complex natural formation. Recent research by scientists is increasingly confirming that the soil is a special natural formation, transitional between living and nonliving.

Thank you guys for the work done. They carried out research work and introduced us to the main soils of our village.

Now we will give the floor to N.V. Bakhaev, he will acquaint us with new technologies that allow us to obtain high yields; but take good care of the soil, since fertility is the main quality of the soil Agro-saving technologies.

The modern concept of agro-saving technologies includes the use of all environmentally sound and environmentally low-hazard methods of protecting cultivated plants from harmful organisms.

The main methods are agrotechnical, biological and chemical.

1. The agrotechnical method includes the following types:

a) Crop rotations. Correct crop rotation is the main part of the farming system and one of the stages of weed control, since crops affect different types of weeds in different ways.

b) Tillage is essential in weed control.

2. The biological method involves the control of weeds, crops of cultivated plants that are highly competitive in relation to weeds, that is, phytocenoses of some crops strongly suppress the development of weeds (rye, winter wheat).

Biological objects are also used - insects, microorganisms, nematodes, which suppress the growth and development of weeds. But this method has not yet received widespread development in Russia.

3. Chemical method. Currently, herbicides are actively used. It is not decisive in relation to other methods, but is used in combination with them. Due to the complex and not always uniquely beneficial effect of pesticides on ecosystems. Their use should be rational, that is, economically and environmentally sound.

All of the above agro-saving technologies, plus the introduction of mineral fertilizers, a natural factor, (weathering, washing out and so on) all the same, it has a negative impact on soil fertility, that is, humus content and, of course, there is a problem of restoring soil fertility, and one of the ways to save what is left is the introduction of organic fertilizers, the biological method and rationally ecologically sound agricultural methods.

Homework: Individual multilevel assignments.

Verification of the actual material.

1. Why is there a change in soil?
2. Who is the founder of the science of soil science?
3. What are the most fertile soils?

Ability to work with the map.

1. What soils are located in the Yaroslavl region?
2. What soils formed in the lower reaches of the Volga River?
3. Determine the soil on the Kola Peninsula?

Causal relationships.

1. Why is the accumulation of humus in the forest zone decreasing?
2. Why are the most fertile soils in Russia - chernozems?
3. Why do taiga soils contain little humus, but high acidity?

Creative application of knowledge.

1. Give examples proving the negative impact of humans on soil, leading to its degradation.
2. Give examples of soil protection.
3. Why use fertilizers with care?

Reflection:

1. I appreciate my work ...
2. I found out today ...
3. I was…