The specific layer of the soil profile formed as a result of the effects of the soil processes.
Soil Pokrov - A combination of soils covering the earth's surface.

In the process of soil formation, primarily under the action of vertical (ascending and descending) streams of substance and energy, as well as the heterogeneity of the distribution of living matter, the initial breed is separated by genetic horizons. Often the soils are formed on initially vertically inhomogeneous bicked rocks, which postpones the imprint to the soil formation and the combination of horizons.

The horizons are considered as a homogeneous (on the scale of the entire soil thickness) of the soil portions, interconnected and interdependent, differing in chemical, mineralogical, particle size distribution, physical and biological properties. The horizon complex, characteristic of this type of soil formation, forms soil profile.

For the horizons, an alphabetic design is made to record the structure of the profile. For example, for ferrous-podzolic soil: A 0 -a 0 a 1 -a 1 -a 1 A 2 -A 2 -A 2 B-BC-C .

The following types of horizons are allocated:

• Organogenic - (litter (A 0, O), peat horizon (T), humorous horizon (A H, H), Dernin (A D), humus horizon (a), etc.) - characterized by biogenic accumulation of organic matter.
• Elwali - (podzolic, lessed, degenerate, segregated horizons; denotes the letter E with indexes, or a 2) - characterized by the removal of organic and / or mineral components.
• Illuvual - (B with indexes) - characterized by accumulation of substances made of eluvial horizons.
• Metamorphic - (b m) - are formed during the transformation of the mineral part of the soil in place.
• Hydrogenic accumulative - (s) - are formed in the zone of maximum accumulation of substances (easily soluble salts, gypsum, carbonates, iron oxides, etc.), brought by groundwater.
• Corn - (k) - horizons, sacted by various substances (easily soluble salts, plaster, carbonates, amorphous silica, iron oxides, etc.).
• Gley - (G) - with prevailing recovery conditions.
• Subsided - The mother breed (C), from which the soil was formed, and lowering the underlying rock (D) of another composition.

Solid phase soil

The soil is highly dispersed and has a large total surface of solid particles: from 3-5 m² / g in sandy up to 300-400 m² / g in clay. Due to the dispersion of the soil, there is a significant porosity: the amount of pores can reach from 30% of the total volume in wetled mineral soils up to 90% in organogenic peat. On the middle, this figure is 40-60%.

The density of the solid phase (ρ s) of mineral soils ranges from 2.4 to 2.8 g / cm³, organogenic: 1.35-1.45 g / cm³. The density of the soil (ρ b) is lower: 0.8-1.8 g / cm³ and 0.1-0.3 g / cm³, respectively. Porosity (Porosity, ε) is associated with densities by the formula:

ε \u003d 1 - ρ b / ρ s

Mineral part of the soil

Mineral composition

About 50-60% of the volume and up to 90-97% of the soil mass make up mineral components. The mineral composition of the soil differs from the composition of the rock on which it was formed: the older than the soil, the stronger this is the difference.

Minerals that are residual material during weathering and soil formation are called primary. In the zone of hypergenesis, most of them are unstable and in one way or another is destroyed. Olivine, amphiboles, pyroxes, nepheline are one of the first. Field spasps are more stable, constituting up to 10-15% of the mass of the soil solid phase. Most often, they are represented by relatively large sandy particles. High resistance is distinguished by epidot, dysten, pomegranate, stavolite, zircon, tourmaline. Their content is usually insignificant, but it allows you to judge the origin of the mother breed and the time of the soil formation. The greatest stability is quartz, which is weathering over several million years. Due to this, under conditions of prolonged and intensive weathered, accompanied by the removal of the destruction of minerals, its relative accumulation occurs.

Soil is characterized by high content secondary mineralsFormed as a result of deep chemical transformation of primary, or synthesized directly in the soil. Particularly important among them are the role of clay minerals - kaolinitis, montmorillonite, galluisite, serpentine and a number of others. They have high sorption properties, a large capacity of cationic and anion exchange, the ability to swell and retain water, stickiness, etc. These properties are largely due to the absorption capacity of soils, its structure and, ultimately, fertility.

The content of oxide minerals and iron hydroxides (lymonitis, hematitis), manganese (ledity, pyrochit, manganit), aluminum (Gibbsit), etc., also strongly affecting the properties of the soil - they are involved in the formation of a structure, soil absorbing complex (especially in strongly weathered tropical soils) take part in oxidative remediation processes. Carbonates (calcite, aragonite, see carbonate-calcium equilibrium in soils) play a major role in the soils. In the arid regions in the soil, easily soluble salts are often accumulated (sodium chloride, sodium carbonate, etc.), affecting the entire course of the soil process.

Grading

Triangle Ferre

In soils there may be particles with a diameter of both less than 0.001 mm and more than a few centimeters. A smaller diameter of particles means a large specific surface area, and this, in turn, the large values \u200b\u200bof the capacitance of cationic metabolism, water-holding ability, better aggregation, but smaller proceeding. Heavy (clay) soils can have problems with air-containing, light (sandy) - with water regime.

For detailed analysis, the entire possible range of sizes are divided into areas called fractions. Unified classification of particles does not exist. In the Russian soil scarecrow, N. A. Kaczynsky was adopted. The characteristic of the particle size (mechanical) of the soil composition is given on the basis of the content of the physical clay fraction (particles less than 0.01 mm) and physical sand (more than 0.01 mm) taking into account the type of soil formation.

In the world, the determination of the mechanical composition of the soil on the triangle of the Ferre is also widely applied: the proportion of dusty is postponed on one side ( sILT., 0.002-0.05 mm) particles, on the second - clay ( clay., <0,002 мм), по третьей - песчаных (sand.0.05-2 mm) and the location of segments is located. Inside the triangle is divided into sections, each of which corresponds to one or another particle sizeary composition of the soil. The type of soil formation is not taken into account.

Organic of soil

The soil contains a number of organic matter. In organogenic (peat) soils, it can prevail in most and mineral soils, its number does not exceed a few percent in the upper horizons.

The composition of the organic substance of the soil includes both plant and animals, not losing the features of an anatomical structure and individual chemical compounds, called humus. The latter is both non-specific substances of the known structure (lipids, carbohydrates, lignin, flavonoids, pigments, wax, resins, etc.), which are up to 10-15% of the total humus, and the specific humus acids formed in the soil.

Humus acids do not have a definite formula and are a whole class of high molecular weight compounds. In the Soviet and Russian soil science, they are traditionally divided into humic and fulvocyuslotes.

The elemental composition of humic acids (by mass): 46-62% C, 3-6% N, 3-5% h, 32-38% O. Fulvocuslot composition: 36-44% C, 3-4.5% N, 3-5% h, 45-50% o. In both compounds there are sulfur (from 0.1 to 1.2%), phosphorus (hundredths and tenths%). Molecular weights for humic acids are 20-80 kDa (minimum 5 kDa, maximum 650 kDa), for fulvocoslotals 4-15 kDa. Fulvocyuslots are movable, soluble on the entire range (humic falls into the precipitate in an acidic environment). The ratio of the carbon of humic and fulvocoslot (C GK / C FC) is an important indicator of humus state of soil.

In the molecule of humic acids, the kernel is isolated, consisting of aromatic rings, including nitrogen-containing heterocycles. Rings are connected by "bridges" with double bonds that create extended conjugation chains that cause the dark color of the substance. The kernel is surrounded by peripheral aliphatic chains, including hydrocarbon and polypeptide types. Circuits carry various functional groups (hydroxyl, carbonyl, carboxyl, amino groups, etc.), which causes a high absorption capacity - 180-500 mG-eq / 100 g.

The structure of fulvocoslot is known significantly less. They have the same composition of functional groups, but a higher absorption capacity - up to 670 MG-EQ / 100 g.

The mechanism for the formation of humus acids (humification) is not fully studied. According to the condensation hypothesis (M. M. Kononova, A. G. Pantov) these substances are synthesized from low molecular weight organic compounds. According to the hypothesis, L. N. Alexandrova humus acids are formed in the interaction of high molecular compounds (proteins, biopolymers), then gradually oxidized and split. According to both hypothesians, enzymes formed mainly by microorganisms take part in these processes. There is an assumption about purely biogenic origin of humus acids. For many properties, they resemble the dark-painted pigments of mushrooms.

Soil structure

The structure of the soil affects the penetration of air to the roots of plants, the deduction of moisture, the development of the microbial community. Depending only on the size of the aggregates, the harvest may vary. The structure is optimal for the development of plants in which aggregates of 0.25 to 7-10 mm dominate (agronomically valuable). An important property of the structure is its strength, especially waterproofability.

The prevailing form of aggregates is an important diagnostic sign of the soil. It is distinguished by a rounded-round (grain, lumpy, chump, dusty), prism (pillars, prism, prismatic) and stovetovoid (tile, scaly) structure, as well as a number of transitional forms and gradations in size. The first type is characteristic of the upper humus horizons and causes greater appendix, the second - for the illuvual, metamorphic horizons, the third - for eluvial.

Tompetions and inclusions

Main article: Soil neoplasms

Neof formation - accumulation of substances formed in the soil during its formation.

The neoplasms of iron and manganese are widespread, whose migration ability depends on the redox potential and is controlled by organisms, especially bacteria. They are represented by concretions, tubes along the progress of roots, crusts, etc. In some cases, the cementation of soil mass occurs with ferrous material. In soils, especially arid and semi-samide regions, limestone neoplasms are distributed: taxes, fadings, pseudomyceliums, concretion, cortical education. The neoplasms of gypsum, also characteristic of arid areas, are represented by towing, druses, gypsum roses, crusts. There are neoplasms of easily solubular salts, silica (powder in eluvial-illuvially differentiated soils, opal and chalcedone bases and barks, tubes), clay minerals (Kutans - skewers and crusts formed during the illuvial process), often together with humus.

TO inclusions Refers any objects in the soil, but not related to the process of soil formation (archaeological find, bones, shells of mollusks and simplest, fragments of rock, garbage). An ambiguously assignment to inclusion or neoplasms of coprolites, wormochin, krootin and other biogenic formations.

Liquid soil phase

Water condition in soil

In the soil, the water is distinguished and free. The first particles of the soil are so firmly held out that it cannot move under the influence of gravity, and free water is subordinate to the law of earthly attraction. The bound water in turn is divided into chemically and physically connected.

Chemically connected water is part of some minerals. This water is constitutional, crystallization and hydrate. Chemically linked water can be removed only by heating, and some forms (constitutional water) - mineral calculation. As a result of the selection of chemically bound water, the body properties change so much that we can talk about the transition to a new mineral.

Physically associated soil water keeps surface energy. Since the magnitude of surface energy increases with an increase in the total total surface of the particles, the content of physically bound water depends on the size of the particles, the compound soil. Particles are larger than 2 mm in diameter do not contain physically bound water; Only particles having a diameter of less specified have this ability. In particles with a diameter of 2 to 0.01 mm, the ability to retain physically bound water is weakly expressed. It increases in the transition to particles less than 0.01 mm and is most pronounced in co-colloid and especially colloidal particles. The ability to retain physically bound water depends not only on the particle size. A certain effect has a form of particles and their chemical engineering composition. Increased ability to retain physically related water has a humus, peat. Subsequent layers of particle water molecules keeps with incomplete force. It loosely connected water. As the particle donates from the surface, the attraction of water molecules gradually weakens. Water goes into free state.

The first layers of water molecules, i.e. Gigroscopic water, soil particles are attracted with a huge force measured by thousands of atmospheres. Being under such a large pressure, the molecules of firmly bound water are very close to that changes many properties of water. It acquires quality as a solid body .. loosely connected water soil holds with less power, its properties are not so sharply different from free water. Nevertheless, the attraction force is still so great that this water does not obey the strength of earthly attraction and differ from free water for a number of physical properties.

Capillary diet causes absorption and retention in the suspended state of moisture, brought by atmospheric precipitation. The penetration of moisture on the capillary pores into the depths of the soil is extremely slow. The water permeability of the soil is due to the main non-pepillary ductility. The diameter of this pores is so large that the moisture cannot be held in suspended and freely seeps into the depths of the soil.

During the flow of moisture on the surface of the soil, the soil is saturated at first to the state of field moisture intensity, and then filtering on non-pepillary wells occurs through the layers saturated with water. On cracks, landscape moves and other large wells, water can penetrate into the depths of the soil, ahead of the saturation of water to the value of field moisture intensity.

The higher the noncapillary diet, the higher the water permeability of the soil.

In soils, in addition to vertical filtration, there is a horizontal intravenous moisture movement. The moisture incoming in the soil, having encountered a layer on its path with reduced water permeability, moves inside the soil over this layer in accordance with the direction of its slope.

Solid Phase Interaction

Main article: Soil absorbing complex

The soil can hold in her substance on different mechanisms (mechanical filtering, adsorption of small particles, the formation of insoluble compounds, biological absorption), the most important of which is the ion exchange between the soil solution and the surface of the soil solid phase. The solid phase due to the chip of the crystal lattice of minerals, isomorphic substitutions, the presence of carboxyl and a number of other functional groups in the composition of the organic substance is charged mainly negatively, therefore the cation exchange ability of the soil is most pronounced. Nevertheless, positive charges, causing anion exchange, are also present in the soil.

The entire totality of the components of the soil with ion exchange ability is called the soil absorbing complex (PPK). The ppk ions are called exchange or absorbed. The characteristic of the PPK is the cationic metabolic capacity (ECEC) - the total number of exchange cations of the same generated by the soil in the standard state - as well as the amount of exchange cations, which characterizes the natural state of the soil and does not always match the ECE.

The relations between the exchange cations of the PPK do not coincide with the relationship between the same cations in the soil solution, that is, an ion exchange proceeds selectively. Preferably, cations with a higher charge are absorbed, and with their equality, with a larger atomic mass, although the properties of the PPK components can somewhat violate this pattern. For example, Montmorillonite absorbs more potassium than hydrogen protons, and the kaolinite is the opposite.

Exchange cations are one of the direct sources of mineral nutrition of plants, the composition of the PPK is reflected in the formation of organic and mineral compounds, the structure of the soil and its acidity.

Soil acidity

Soil air.

Soil air consists of a mixture of various gases:

1. oxygen, which enters the soil from atmospheric air; Its content may vary depending on the properties of the soil itself (its loosenness, for example), on the number of organisms using oxygen for breathing and metabolic processes;
2. carbon dioxide, which is formed by the respiration of the soil organisms, that is, as a result of oxidation of organic substances;
3. methane and its homologues (propane, butane), which are formed as a result of the decomposition of longer hydrocarbon chains;
4. hydrogen;
5. hydrogen sulfide;
6. nitrogen; More likely the formation of nitrogen in the form of more complex compounds (for example, urea)

And this is not all gaseous substances that make up soil air. Its chemical and quantitative composition depends on the organisms contained in the soil, the content of nutrients in it, the conditions of weathering of the soil, etc.

Living organisms in soil

Soil is the habitat of many organisms. Creatures living in the soil are called pedobionats. The smallest of them are bacteria, algae, fungi and single-celled organisms living in soil waters. In one m³, it can dwell up to 10 ⁴ organisms. Invertebrate animals, such as ticks, spiders, beetles, sickness and rain worms live in the soil air. They feed on plant residues, fungal and other organisms. Vertebrate animals live in the soil, one of them is Mole. It is very well adapted to habitat in absolutely dark soil, so it is deaf and practically blind.

The heterogeneity of the soil leads to the fact that for organisms of different sizes, it acts as a different environment.

• For small soil animals, which are united by nanofauna (protozoa, provicrats, squabbles, nematodes, etc.), the soil is a system of microcolates.
• For breathable air, somewhat larger animal soil appears as a system of small caves. Such animals are combined under the name of the microfaine. The size of the representatives of the soil microbine - from the tenths of up to 2-3 mm. This group includes mainly arthropods: numerous groups of ticks, primary transcenderent insects (collebroles, proturats, two-dimensions), small types of winged insects, multi-like Symphyls, etc. They have no special devices to choke. They are crawling along the walls of the soil cavities with the help of the extremities or wriggle-like. The soil air saturated with water vapors allows you to breathe through the covers. Many species do not have a trachene system. Such animals are very sensitive to drying.
• Large soil animals, with body sizes from 2 to 20 mm, called mesofauna representatives. These are larvae insects, multi-ninexes, enhitreides, rain worms, etc. For them, the soil is a dense medium that has significant mechanical resistance when driving. These relatively large forms are moving in the soil or expanding the natural wells by spreading soil particles, or Roy new moves.
• Megafaun or Macrofaun Soils are large agricultural, mainly from the number of mammals. A number of species spend in the soil all life (choppers, shapes, chips, Eurasia croes, subtleturots of Africa, the silent mole of Australia, etc.). They are in the soil whole systems of moves and holes. The appearance and the anatomical features of these animals reflect their adaptability to the rising underground lifestyle.
• In addition to the permanent inhabitants of the soil, among large animals you can select a large ecological group of the inhabitants of Nor (Susliki, Surki, Tushkanchiki, rabbits, badgers, etc.). They feed on the surface, but breed, winter, relax, they are saved from danger in the soil. A number of other animals use their holes, finding a favorable microclimate and shelter from enemies. Norcons have the features of the structure characteristic of terrestrial animals, but have a number of devices associated with a thorough way of life.

Spatial organization

In nature, there are practically no such situations in order to stretch a lot of kilometers from any one soil with immutable properties in space. At the same time, the differences in soil are caused by differences in soil formation factors.

The natural spatial placement of soils in small territories is called the structure of soil cover (SPP). The initial unit of the NGN is the elementary soil area (EPA) - soil education, within which there are no soil-geographical boundaries. Alternating in space and in one degree or another, genetically related EPA form soil combinations.

Soil formation

Soil-forming factors :

• Elements of the natural environment: soil-forming breeds, climate, live and dead organisms, age and terrain,
• as well as anthropogenic activities that have a significant impact on the soil formation.

Primary soil formation

The Russian soil has a concept that any substrate system that ensures the growth and development of plants "from seed to seed" is soil. The idea of \u200b\u200bthis discussion, since it denies the Dochevsky principle of historicality, implying certain maturity of soils and separation of the profile on genetic horizons, but useful in knowledge of the general concept of soil development.

The safety state of the soil profile until the first signs of horizons can be determined by the term "initial soils". Accordingly, the "initial stage of soil formation" is allocated - from the soil "by wagge" until the time when a noticeable profile differentiation appears on the horizons, and it will be possible to predict the classification status of the soil. The term "young soils" is invited to consolidate the stage of "young soil" - from the emergence of the first signs of horizons until the time when genetic (more precisely, morphol-analytical appearance will be quite pronounced for diagnosis and classification from the general position of soil science.

Genetic characteristics can be given before reaching the profile maturity, with an understandable share of prognostic risk, for example, "initial turf soils"; "Young propoderous soils", "young carbonate soils". With this approach, the nomenclature difficulties are resolved naturally, on the basis of the general principles of soil and environmental forecasting in accordance with the formula of the Dokuchaev -Yenni (representation of the soil as the functions of soil factors: S \u003d F (Cl, O, R, P, T ...)).

Anthropogenic soil formation

In the scientific literature for lands after mining and other violations of the soil cover, the generalized name "Technogenic landscapes" was entrenched, and the study of the soil formation in these landscapes was imposed in "Recultivating soil science". The term "techno-industry" was also proposed, in fact, representing an attempt to unite the Dochevsky tradition of "-Comes" with man-made landscapes.

It is noted that it is more logical to apply the term "technoce" to those soils that are specifically created in the process of mining technology by moving the surface and fastening specially removed humus horizons or potentially fertile soils (lessa). The use of this term for genetic soil science is unlikely to be justified, since the final, the climax product of the soil formation will not be a new "-With", but zonal soil, for example, a dernovo-podzolic, or the delicate-gley.

For technologically disturbed soils, the terms "initial soil" were used (from "zero - moment" before the appearance of horizons) and "young soils" (from the appearance of the diagnostic signs of mature soils), indicating the main feature of such soil entities - the temporary stages of their Evolution of undifferentiated breeds in zonal soil.

Soil classification

Unified generally accepted classification of soil does not exist. Along with the international (Classification of the Soils FAO and the WRB replaced it in 1998) in many countries of the world there are national soil classification systems, often based on fundamentally different approaches.

In Russia by 2004, the Special Commission of the Soil Institute. V. V. Dokuchaeva, led by L. L. Shishimov, prepared a new classification of soil, which is the development of the 1997 classification. However, the Russian Soilists continues to be actively used and the classification of the Soils of the USSR of 1977.

From the distinguishing features of the new classification, it is possible to refuse to attract for the diagnosis of factor-environmental and regime parameters for the diagnosis, difficult to be diagnosed and often defined by the researcher is purely subjectively, focusing at the soil profile and its morphological features. In this, a number of researchers see the departure from genetic soil, making the main emphasis on the origin of soils and soil formation processes. In the 2004 classification, the formal criteria for the attribution of the soil to a specific taxon are introduced, the concept of a diagnostic horizon is attracted, adopted in international and American classifications. Unlike WRB and American SOIL TAXONOMY, in the Russian classification, horizons and signs are not equal, and strictly ranked on taxonomic significance. An unquestionable innovation of the 2004 classification was the inclusion of anthropogenic-transformed soils.

In the American School School, the SOIL Taxonomy classification is used, which also has a distribution in other countries. Its characteristic of its peculiarity is the deep study of the formal criteria for attributing soils to a particular taxa. Soil names designed from Latin and Greek roots are used. The classification scheme traditionally includes soil series - groups of soils other than granulometric composition, and having an individual name - the description of which began in mapping the soil bureau of the United States at the beginning of the 20th century.

Soil classification is a soil separation system by origin and (or) properties.

• The type of soil is the main classification unit characterized by the generality of the properties caused by the modes and process of soil formation, and the unified system of the main genetic horizons.
  • The soil subtype is a classification unit within the type characterized by qualitative differences in the system of genetic horizons and on the manifestation of imposed processes characterizing the transition to another type.
    • The generation of the soil is a classification unit within the subtype, determined by the characteristics of the composition of the soil-absorbing complex, the nature of the salt profile, the main forms of neoplasms.
      • Type of soil is a classification unit within the genus, quantitatively different from the degree of severity of the soil-forming processes that determine the type, subtype and generation of soil.
        • A variety of soil is a classification unit that takes into account the separation of soils in the particle sizeary composition of the entire soil profile.
          • The soil discharge is a classification unit, grouping soils by the nature of the soil-forming and underlying rocks.

Patterns of distribution

Climate as a factor of the geographical distribution of soil

The climate is one of the most important factors of soiling and the geographical distribution of soils - largely determined by cosmic causes (the amount of energy obtained by the earth's surface from the Sun). The climate is associated with the manifestation of the most common laws of soil geography. It affects the soil formation as directly by determining the energy level and hydrothermal regime of soils, and indirectly, affecting other factors of soil formation (vegetation, vital activity of organisms, soil-forming rocks, etc.).

The direct influence of the climate on the geography of soil is manifested in different types of hydrothermal conditions of soil formation. The heat and water soil modes affect the nature and intensity of all physical, chemical and biological processes occurring in the soil. They are regulated by the processes of physical weathering of rocks, the intensity of chemical reactions, the concentration of the soil solution, the ratio of the solid and liquid phase, the solubility of the gases. Hydrothermal conditions affect the intensity of biochemical activity of bacteria, the rate of decomposition of organic residues, organisms and other factors, therefore, in different parts of the country with a different heat mode, the rate of weathering and soil formation, the power of the soil profile and weathering products are significantly different.

The climate determines the most common patterns of soil propagation - horizontal zonality and vertical explanation.

The climate is the result of the interaction of climate-forming processes occurring in the atmosphere and the active layer (oceans, cryosphere, surfaces of sushi and biomass) - the so-called climate system, all the components of which continuously interact with each other, exchanging substance and energy. Climate-forming processes can be divided into three complexes: heat management processes, moisture revolution and atmospheric circulation.

Soil value in nature

Soil as a habitat of living organisms

The soil has fertility - is the most favorable substrate or habitat for the overwhelming majority of living beings - microorganisms, animals and plants. It is also indicative that according to their biomass soil (land drying) almost 700 times greater than the ocean, although the share of sushi is less than 1/3 of the earth's surface.

Geochemical functions

The property of various soils in different ways to accumulate a variety of chemical elements and compounds, one of which is necessary for living beings (biofil elements and trace elements, various physiologically active substances), and others are harmful or toxic (heavy metals, halogen, toxins, etc.) , manifests itself on all plants and animals living on them, including human. In agronomy, veterinary and medicine, such interrelation is known in the form of so-called endemic diseases, the reasons for which were disclosed only after the work of the soils.

The soil has a significant impact on the composition and properties of surface, groundwater and the entire hydrosphere of the Earth. Filtering through the soil layers of water removes from them a special set of chemical elements characteristic of soils of waterborne areas. And since the main economic indicators of water (its technological and hygienic value) are determined by the content and ratio of these elements, the impairment of soil cover is also manifested in changing the quality of water.

Regulation of the composition of the atmosphere

Soil is the main regulator of the composition of the Earth's atmosphere. It is due to these activities of soil microorganisms, on a huge scale of producing various gases - nitrogen and its oxides, oxygen, dioxide and carbon oxide, methane and other hydrocarbons, hydrogen sulfide, a number of other volatile compounds. Most of these gases cause a "greenhouse effect" and destroy the ozone layer, as a result of which the change in the properties of the soil can lead to climate change on Earth. It is not randomly taking place at present shift in climatic equilibrium of our planet, specialists are associated primarily with impaired soil cover.

Economic importance

The soil is often referred to as the main wealth of any state in the world, since it also produces about 90% of human food products. Soil degradation is accompanied by indestructible and hunger, leads to the poverty of states, and the death of soils can cause the death of all mankind. Also, the Earth was used in antiquity as a building material.

V. V. Dokuchaev (1846-1903)

Soil is the thin top layer of the earth's crust, which gives life to plants. This is an independent natural body, which is something among the living and dead matter. Litosphere, atmosphere, hydrosphere and biosphere interact in the soil, and the density of the liquid substance of the planet is maximum.

The most valuable property of the soil is fertility, i.e. ability

provide plants with the necessary nutrients and moisture.

The soil consists of mineral particles, organic matter mainly vegetable origin, soil water, soil air and inhabiting her living organisms. In various parts of the Earth, the soil thickness ranges from several centimeters to 2-3 meters.

The soil is formed very slowly, for the full update of its mineral part to the depth of 1 m, 10,000 years is necessary.

The founder of modern soil science V.V. Dokuchaev believed that, like minerals, plants and animals, soils are special natural-historical bodies. They are formed under the influence of several soil formation factors operating simultaneously.

Mountain breeds on which the soil are formed are called maternal or soil-forming, they serve as a source of the mineral part of the soil and determine its chemical, mineral and mechanical composition.

The thermal and water modes of the soil formation depend on the climate, as well as the weathering speed of rocks. The vegetation supplies organic substances into the soil and significantly affects its microclimate.

Animals and microorganisms that inhabit the soil are stirred and breaking it, and also accelerate the decomposition of organic residues. Depending on the relief, heat and moisture are redistributed, and the chemical composition and mode of ground and soil waters affect many soil processes.

Human activity has a tremendous impact on the formation of the soil: he cultivates the land, and to get a good harvest, makes a fertilizer in the soil.

The formation of soil begins with weathered - the destruction and grinding of rocks.

Factors affecting soil formation

On the loose moistened mass appear first bacteria, mushrooms and algae. In the process of their livelihoods, a thin film of the organic matter is formed, at which lower plants are the first to settle - mosses and lichen. Decommissioning plants and remains of animals recycle microorganisms, organic matter becomes greater.

IN the soil is formed by a humid, a black layer, which is calledgumus. It contains the basic nutrients required by plants. The more humus in the soil, the more festive.

IN a result of long-term soil formation processes occurs the separation of soil stratum on the horizons is homogeneous layers with the same color, structure, structure and other features. For example, in podzolic soils of mixed forests of a moderate belt from top to bottom, the horizon A1 is usually isolated, in which the accumulation of organic matter and the formation of humus is accumulated; Horizon A2 - leaching, from which, with a sufficient amount of precipitation, a part of organic and mineral compounds occurs; The in-beam horizon where relatively movable tillage products accumulate from the upper horizons; Horizon C - soil-forming breed.

According to the degree of severity of individual soil horizons, their power, chemical composition determine the types of soils - chernozem, podzolic soils, salt maps, etc.

Why are some soil loose, and other solid?

Sand and clay particles, of which the soil consists, let me in different way. Sand quickly absorbs water, because it consists of quite large particles that are not very tightly in contact with each other, and water is easily seeping. Clay particles have a smaller size and are so tightly pressed to each other that water between them is with difficulty.

By the ratio of sand and clay particles, the mechanical composition of the soil is judged. If there are more sandy particles in the soil, then it is a light sandy soil, and if there are plenty of small clay - heavy clay. In the suction and thin soils, the ratio of sand and clay is about the same.

The ability of the soil to decay on lumps of various shapes and sizes are called the structure of the soil. Combany and grainy soils are very fertile, and the structureless soils consisting of small dusty particles do not allow air and moisture to penetrate the roots of plants, so they are not good.

particles

passes

clay

particles

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The formation of the soil depends on the combination of soil formation factors that differ in extensive spaces of the Earth. For example, where the air temperature is low, there are little precipitation and the vegetation is scanty, the soil layer is thin and contains a little humus. But in areas with sufficient heat and precipitation, with rich herbal vegetation, powerful fertile soils are formed.

Gumus (from Lat. Humus - Earth, soil), or by humus, is called a specific organic matter of the soil. Gumus accumulates in various quantities in the upper soil layer and is usually dark. It is formed as a result of a complex biochemical process of transformation of dead plant residues and other biogenic products into specific humus substances - humic acids, fulvocyuslots and Gumin.

The remains of green plants that have fallen into the crowd of the soil or on its surface are quickly decomposed, lose their shape and the initial structure. Active participation in this process is taken by soil animals and microbes. Some compounds (part of carbohydrates and proteins, fats) are converted into carbon dioxide, water, mineral salts, which are re-included in the biological circulation. At the same time, microorganisms are synthesized by complex substances, staining the soil in a dark color. This is a humus, which contains the most important elements of plant nutrition - nitrogen, phosphorus, sulfur, etc., which are influenced by microorganisms become available to plants. Thus, soil fertility depends on the content of humus in them.

Gumus reserves are highest in the soils of prairies and high-level steppes and are minimal in the soils of the tundra and deserts. In Chernozem, the content of humus reaches 9-12%, and the humus horizon usually has the highest power - 25-100 cm. Podzolic soils contain only 3-4% humus.

IN early XX century Great Russian scientist

V.V. Dokuchaev for the first time formulated the law of soil zonality: "Soils ... should be located on the earth's surface zero, in the strictest dependence on climate, vegetation, etc.." On the globe of the soil naturally changed on the plains from the equator to the poles, and in the mountains - from the foot to the vertices.

However, it is often even inside one natural zone, the soil formation factors differ greatly, therefore, together with the main type of soil, characteristic of this natural zone, within its limits a large number of other types of soil is formed. In this regard, the soil map of the world is characterized by extraordinary varnish.

Of all the soils of the Earth, Black Soils are the most fertile. They are formed in the area of \u200b\u200bsteppes and forest-steppes, where the climate is dry and relatively warm.

Tundrovo Gley Soils forms in the tundra zone under conditions of constant convergence and low temperatures. They are low. because of Difficult access of oxygen in these soils blue-gray Guery horizon.

Podzolic soilscharacteristic for zone of coniferous and mixed forests. Where precipitation falls more than evaporates, a wash mode is formed in soils, in which the products of decay of organic and mineral substances quickly take place in the lower soil horizons. The clarified podzolic horizon is formed, the color resembles ash. Podzolic soils contain little humus and require fertilizer.

Gray forest soils form under mixed, wide forests and forest-steppes in temperate climates. Soft winter, warm summer and moderate moisturizing lead to the fact that the humus horizon can reach 50 cm.

Serozos - soil deserts and semi-deserts. They are formed at high temperatures and disadvantage of moisture. The humus in them is not enough, it accumulates only due to the dieting spring herbal vegetation and is only a few centimeters. These soils can be fertile only with good irrigation.

Ferrallitic soilsform under wet equatorial and tropical

forests on the heavily destroyed rocks of the ancient sushi - the ferallization crust of weathering. Due to the contents of a large amount of iron and aluminum oxides in the mother and aluminum, red, yellow and brown colors are acquired and therefore worn the name of the redstone, yellow-red, red, reddish-brown, red-and-red soils. The humus layer in these soils is large enough.

Some Types of Soils Completed on the Earth Bowl