Practical work identifying the main soil formation conditions. Practical work identifying the conditions for the formation of the main types of soils and assessing their fertility
Subject: Determination from maps of soil formation conditions for the main zonal soil types (amount of heat and moisture, relief, nature of vegetation)
Soils and soils are a mirror and
quite a true reflection
the result of centuries of interaction
between water, air, earth, with
on the one hand, vegetation and
animal organisms
and the age of the territory on the other.
V. V. Dokuchaev
Goals of work:
1. Get acquainted with the main zonal soil types in our country. Determine the conditions for their formation.
2. Check and evaluate the ability to work with various sources of geographic information, draw generalizations and conclusions based on their analysis.
Sequence of work:
1. Based on the analysis of the text of the textbook, p. 93-95, fig. 44, soil map (atlas) and soil profiles (textbook, p. 92, Fig. 43) determine the conditions of soil formation for the main types of soils in Russia.
2. Present the results of your work in the form of a table.
^ Working on options.
Option I – tundra, podzolic, sod-podzolic;
Option II – gray forest soils, chernozems, brown soils of semi-deserts.
| Options | Soil types | ^ Geographical position | Conditions of soil formation (ratio of heat and moisture, nature of vegetation) | Features of the soil profile | Humus content | Fertility |
| I | Tundra | North of Russia, coast of the Arctic Ocean | Lack of heat, low evaporation and, as a consequence, excess moisture, no woody vegetation, there are only grasses and low shrubs + mosses and lichens, a lot of swamps, the presence of permafrost. | There are no clearly defined soil horizons, the soils are acidic, and gleyization processes are characteristic. Low soil thickness. | Up to 10%, in peaty and humus soils up to 40%, the thickness of the humus horizon is up to 20 cm. | Very low. |
| I | Podzolic | Taiga zone of Russia | There is a slightly greater amount of heat than in the tundra, but there remains an excess of moisture, a clear predominance of woody vegetation, and a lot of swamps. Flushing mode. | The soil horizon, located under the humus horizon and having the color of ash, is strongly pronounced. | 1-6%. Humus horizon up to 20 cm. | Low. |
| I | Sod-podzolic | Southern taiga and mixed forests | Some excess moisture, more heat than in the northern taiga and tundra, woody vegetation predominates, but herbaceous vegetation is more diverse. Flushing mode. | The expression of the podzolic horizon is preserved, but with the presence of the sod process. | 1-6%. Humus horizon up to 20 cm | Low. |
| II | Gray forest | Mixed (south) and broad-leaved forests, forest-steppe | Optimal ratio heat and moisture. Woody and herbaceous vegetation is varied. Periodic flushing mode. | The soil is thicker than soddy-podzolic soil, the humus horizon is thicker, and the process of leaching of organic matter is weakened. | 1-8%. Humus horizon up to 30 cm. | Above average. |
| II | Chernozems | Forest-steppe and steppe of southern Russia | Continental steppe climate with warm summers and cold winters with some lack of moisture, herbaceous vegetation predominates. There is no flushing mode. | Very rich soil with a large humus horizon. | 5-10% in the humus horizon 45-60 cm. | High and very high. |
| II | Brown semi-desert soils | Semi-desert of the Caspian lowland. | Continental climate with hot summers and extreme lack of moisture. The vegetation is sparse and herbaceous. Soil salinization is typical. | Dry soil, often with excess salts and gypsum. | Up to 1.5% in the humus horizon up to 15 cm. | Very low. |
Draw a conclusion.
The nature of the soil and its fertility depend on the climate of the area, as well as on the vegetation growing on it. Dokuchaev's statement is confirmed.
How are soils used by humans?
Soils are a source of agricultural raw materials and food.
Questions in a paragraph
*In which areas of our country do you think irrigation, drainage, and chemical reclamation are used?
Irrigation is used in the southern regions of the country (the south of the Russian Plain, island areas in the south of Siberia). Drainage is carried out in the middle and northern zone of the Russian Plain, Western Siberia, and the south of the Far East. Chemical reclamation is used everywhere.
Questions at the end of the paragraph
1. What is the importance of soils in the life of nature and humans?
Soil is the main source of agricultural products and raw materials for industry. Soils are of great ecological importance. Soil is an important link in the cycle of matter and energy. In the soil, organic matter is converted into inorganic matter.
2. What should the soil be protected from?
Soils should be protected from erosion, chemical pollution, degradation of the upper fertile layer, desertification, and compaction.
3. What types of land reclamation are carried out in our country? What is the reason for the choice of one or another type of reclamation?
Irrigation and watering, drainage, anti-erosion measures, chemical reclamation. The choice of one or another type of reclamation depends on natural conditions and soil type. For example, in arid climates, field irrigation is used, and in excessive moisture, drainage is used.
FINAL ASSIGNMENTS ON THE TOPIC
1. Prove using any soil as an example that soils are a “mirror” of the landscape.
Let's consider the formation of chernozem. Chernozem is the most fertile of all other known types of soil. Chernozem is formed in the steppe and forest-steppe regions of Russia, and its formation itself takes several decades. For the formation of chernozem, the presence of certain natural conditions is necessary, for example, such as a moderately cold and dry climate, an abundance of meadow and steppe vegetation. In the process of decomposition (humification) of a huge amount of vegetation residues that accumulate annually in the soil, the formation and accumulation of so-called humus occurs in the upper layer of soil, which, in fact, is humus. Humus is considered the most valuable element in the composition of chernozem. Thus, flat landscapes, dense grassy vegetation, and certain climatic conditions are factors in the formation of chernozems.
2. Practical work No. 6. Identification of soil formation conditions for the main types of soil (amount of heat, moisture, relief, vegetation). Assessment of their fertility.
Explain what soil fertility depends on. Name the most fertile soils in Russia, explain the geography of their distribution.
The fertility of the soil depends on the content of nutrients, water, air, and its mechanical composition. The amount of humus is of particular importance. The most fertile soils in Russia are chernozems. This soil contains much more humus than all other types. It is formed under conditions of a continental temperate warm climate in the steppe zone and in open areas of forest-steppe.
What soil formation processes occur under conditions of excessive, sufficient and insufficient moisture?
Under conditions of excessive moisture, bog soil formation occurs; under conditions of sufficient moisture, podzolic and soddy-podzolic soil formation occurs; under conditions of insufficient moisture, soddy soil formation occurs.
Give an assessment of the main types of soils in our country. Indicate which of them are most favorable for Agriculture, on which forests are mainly located.
Tundra gley soils are found on plains. They are formed without much influence from vegetation. These soils are found in areas where there is permafrost (in the Northern Hemisphere). Often, gley soils are places where deer live and feed in summer and winter.
Arctic soils are produced by thawing permafrost. This soil is quite thin. The maximum layer of humus (fertile layer) is 1-2 cm. This type of soil has a low acidic environment. This soil cannot be restored due to the harsh climate. These soils are common in Russia only in the Arctic (on a number of islands in the Arctic Ocean). Due to the harsh climate and small layer of humus, nothing grows on such soils.
Podzolic soils are common in forests. There is only 1-4% humus in the soil. Podzolic soils are obtained through the process of podzol formation. A reaction occurs with the acid. That is why this type of soil is also called acidic. Dokuchaev was the first to describe podzolic soils. In Russia, podzolic soils are common in Siberia and the Far East. Such soils must be properly cultivated in agriculture. They need to be fertilized, organic and mineral fertilizers added to them. Such soils are more useful in logging than in agriculture.
Gray forest soils are formed in forest areas. A prerequisite for the formation of such soils is the presence of a continental climate. Deciduous forest and herbaceous vegetation. The places of formation contain an element necessary for such soil - calcium. Thanks to this element, water does not penetrate deep into the soil and does not erode them. These soils are gray in color. The humus content in gray forest soils is 2-8 percent, that is, the soil fertility is average. Gray forest soils are divided into gray, light gray, and dark gray. These soils predominate in Russia in the territory from Transbaikalia to the Carpathian Mountains. Fruit and grain crops are grown on the soils.
Brown forest soils are common in forests: mixed, coniferous and broad-leaved. These soils are found only in warm temperate climates. The soil color is brown. Typically brown soils look like this: on the surface of the ground there is a layer of fallen leaves, about 5 cm high. Next comes the fertile layer, which is 20 and sometimes 30 cm. Even lower is a layer of clay of 15-40 cm. There are several subtypes of brown soils. Subtypes vary depending on temperatures. There are: typical, podzolized, gley (superficial gley and pseudopodzolic). In the territory Russian Federation soils are common in the Far East and the foothills of the Caucasus. Low-maintenance crops such as tea, grapes and tobacco are grown on these soils. Forests grow well on such soils.
Chestnut soils are common in steppes and semi-deserts. The fertile layer of such soils is 1.5-4.5%. On light chestnut soils, farming is possible only with abundant watering. The main purpose of this land is pasture. The following crops grow well on dark chestnut soils without watering: wheat, barley, oats, sunflower, millet. Chestnut soils in Russia are common in the Caucasus, the Volga region and Central Siberia.
Chernozem - this soil contains much more humus than all other types. It is formed under conditions of a continental temperate warm climate in the steppe zone and in open areas of forest-steppe. Decomposition processes occur quickly in the warm season, and partial leaching of humus occurs only in early spring and late autumn. Humus constantly accumulates, creating very high soil fertility. Grain crops (wheat, corn), sunflower, and sugar beets are grown on the chernozem soils of steppes and forest-steppes.
3. What types of activities lead to disruption of natural soil fertility? How can you improve soil fertility?
As a rule, soil disturbance is the result of unsustainable agricultural practices. Soil fertility is lost due to non-compliance with crop rotation, improper application of fertilizers, compaction of soils under the weight of agricultural machinery, and overgrazing of livestock. Soil fertility can also be lost due to erosion, which is caused by improper plowing and deforestation. Soil fertility can be improved through reclamation (irrigation, watering, anti-erosion actions, chemical reclamation) and the introduction of complex crop rotations.
SOILS OF THE TAIGA FOREST ZONE
Podzolic soils are the most common soils in Russia; they predominate in the taiga-forest zone, covering more than 50% of its territory, including about 18% of the area located in the mountainous regions of Central and Eastern Siberia. The taiga-forest zone and the northern part of the forest-steppe zone with gray forest soils are often called the Non-Chernozem Zone, taking into account the commonality of natural and economic characteristics and the peculiarities of farming in this territory.
Soil Formation Conditions
The natural conditions of the taiga-forest zone are extremely diverse due to its enormous extent from north to south (from the tundra to the forest-steppe zone) and from west to east (from the Leningrad region to the shores of the Sea of Okhotsk and the Sea of Japan). The flat, mainly European and West Siberian, parts of the taiga-forest zone are divided from north to south into three subzones based on climatic conditions, vegetation and soil cover: northern, middle and southern taiga. To the east, large areas of the zone are also distinguished, differing in natural conditions and soil cover. Let us note the general indicators of soil formation conditions in the taiga-forest zone.
Climate. The climate of the zone is moderately cold, with increasing continentality to the east. In the regions of Eastern Siberia it is sharply continental, and in the Far East it is monsoonal. The average annual temperature in the west of the European territory of the taiga-forest zone is 4 °C, in its eastern part (Middle Urals) about 1 °C, in Eastern Siberia -7...-16 °C and in the Far East up to 7.5 °C . The annual amount of precipitation in the northern taiga subzone of the central part of European Russia is about 400 mm, in the middle taiga about 500 mm and in the southern taiga about 600 mm. The sum of annual temperatures >10 °C is approximately 1200, 1600 and 2200 °C, respectively. To the west, the amount of precipitation and the sum of temperatures increase, and to the east they decrease.
The main amount of precipitation in the zone falls in the warm season; the annual amount of precipitation over a large area prevails over evaporation by 1.1 - 1.3 times, and this, especially under forests, provides a leaching type of water regime and creates conditions for the formation of podzolic soils. However, in many areas of Eastern Siberia (Central Yakut Lowland, etc.) moisture is insufficient, and the annual amount of precipitation is less than evaporation. The Asian territory, especially Eastern Siberia, is located in a zone of island and continuous permafrost with a permafrost type of water regime widespread here, which has a significant impact on soil formation processes.
Relief. The European part of the taiga forest zone is located within an undulating and ridged plain. In addition to tectonic processes, the formation of its relief, including hills, was greatly influenced by the activity of the Scandinavian, Novo-Zemelsky, Northern Ural glaciers and flows of glacial waters during the Ice Age, as well as wind, colluvial waters and cryogenic processes in the post-glacial period. As a result, a slope relief was formed, dissected by river valleys, with a well-defined gully-beam network, promoting the active development of planar water erosion, especially on arable land.
The West Siberian part of the zone covers the West Siberian Lowland. It is a vast, poorly drained plain. To the east, plateaus and mountainous regions predominate, among which the vast Central Yakut Lowland stands out. In the Far East, among the mountain formations there are lowlands, which are the main agricultural territories.
Soil-forming rocks in the European part and Western Siberia are mainly represented by various Quaternary non-carbonate deposits of glacial, water-glacial and lacustrine-glacial origin of various granulometric compositions (moraines, fluvioglacial sands and sandy loams, cover loams and clays, etc.; In addition to these rocks ancient alluvial and modern alluvial deposits, eluvium and colluvium of bedrock, and sometimes loess-like loams are distinguished.
There is often a binomiality of soil-forming rocks in terms of granulometric composition within the soil profile, which affects the water, physical and other properties of soils. In the regions (excluding mountainous ones) of Central and Eastern Siberia, soil-forming rocks are represented mainly by eluvium and colluvium of bedrock; in the Central Yakut Lowland, Quaternary loess-like loams and sandy loams predominate, and on the plains of the Far East, Quaternary and more ancient rocks of various granulometric compositions predominate.
Vegetation. Taiga forests predominate, mainly coniferous with a moss cover, and in the south of the zone the forest stand consists of deciduous and broad-leaved tree species with an admixture of conifers, with grass and moss cover. Open non-wetlands are occupied by meadow plant associations, and waterlogged areas are occupied by marsh plant associations. There are especially many swamps in the northern part of the zone and within the West Siberian Lowland.
The subzones of the European and West Siberian parts of the zone are characterized by vegetation by the following features.
The northern taiga subzone is occupied by sparse spruce forests with an admixture of birch, larch and aspen with moss, lichen and moss-shrub ground cover. In the western part of the subzone and on light soil-forming rocks, pine forests predominate.
The northern taiga is a subzone of gleyic-podzolic and podzolic illuvial-humus soils.
The middle taiga subzone is sometimes called the green moss dark coniferous spruce forest subzone; There is virtually no herbaceous vegetation under the forest canopy. This is a typical taiga. Pine forests - white moss forests - develop on light rocks. Lichen ground cover is often found. In clearings and fires, conifers give way to birch and aspen.
The middle taiga is a subzone of podzolic soils. The southern taiga subzone is occupied by mixed broad-leaved coniferous forests with moss-grass and herbaceous cover. To the east, the share of broad-leaved species (oak, ash, maple, linden) decreases, and the share of coniferous species, including fir, increases. Clearings and fires, just like in the middle taiga, are quickly occupied by aspen and birch. These tree species, along with conifers, are predominant in the southern taiga subzone of Western Siberia. The soil cover of the southern taiga forms a subzone of soddy-podzolic soils.
The central and eastern Siberian taiga forest zone is characterized by light-coniferous larch forests, while the Far East is characterized by light-coniferous, dark-coniferous and broad-leaved forests.
As noted, the conditions of soil formation change in the taiga-forest zone not only from north to south across subzones, but also from west to east, and this determines the formation of facies characteristics of soils, expressed in the appearance of specific characteristics, properties and regimes in the soils. There are warm (Western and Southern European), temperate (Eastern European), cold (Western and Central Siberian), permafrost (East Siberian and Far Eastern) and cold wet (Pacific) facies - Kamchatka, Sakhalin.
The main processes under the influence of which the formation of the soil cover of the taiga-forest zone occurred are podzolic, soddy and bog (peat formation and gleying). The manifestation of lessivage was also noted, and on the territory of the Central Yakut Lowland - solonetzic, solonchak processes and salinization processes. Let us consider the main soils of the zone: podzolic, sod-podzolic.
Podzolic Soils
Podzolic soils are most common in the middle taiga and northern taiga subzones; they are also found in the southern taiga subzone.
The name “podzolic soils” comes from the popular word “podzol,” which reflects the color of the podzolic layer located under the forest floor, which looks like ash. This name was introduced into scientific literature by V.V. Dokuchaev.
podzolic soils
sod-podzolic
Podzolic soils are divided into two subzonal subtypes: podzolic and gley-podzolic.
The podzolic process is the main soil-forming process under the influence of which podzolic soils were formed. As a result of its manifestation, the destruction of primary and secondary minerals in the upper part of the soil profile and the removal of destruction products into the underlying horizons and groundwater occur.
According to the colloid-chemical theory of K. K. Gedroits, which has had long-term recognition, the main role in podzolization belongs to the hydrogen ion of water. According to the theory of V.R. Williams, the podzolic process is associated with a certain group of specific organic acids (crenoic acids, or fulvic acids in modern terminology), which cause the decomposition of minerals in the solid phase of soils. The theory of podzol formation was further developed as a result of research by I.V. Tyurin, S.P. Yarkov, A.A. Zavalishin, N.P. Remezov, I.N. Antipov-Karataev, A.A. Rode, E.N. Ivanova, I.S. Kaurichev, V.V. Ponomareva, T.V. Aristovskaya and other scientists.
According to modern concepts, podzol formation involves fulvic acids, which predominate in the composition of a specific part of the humus of forest soils, as well as low-molecular organic acids (acetic, formic, citric, etc.) and organic acids formed as a result of the vital activity of soil microorganisms and secreted by plant roots. The chemical interaction of minerals in the layer underlying the forest litter, including those included in the sludge, with acids leads to the formation of easily soluble salts and mobile organomineral compounds, which, due to the dominance of the leaching water regime in the taiga-forest zone, are carried to the lower part of the soil profile or beyond the soil layer.
As a result of the dissociation of acidic products and the dissolution of CO 2 in water, the resulting hydrogen ion enters into exchange reactions with cations of the bases of the soil colloidal complex; their concentration in the soil solution increases significantly; they are also carried down with downward currents of soil solutions. The horizon is gradually depleted of calcium, magnesium, phosphorus, aluminum and other elements, and the removal of iron and manganese leads to its discoloration. When silicates and aluminosilicates are destroyed, secondary quartz is formed in the form of a siliceous powder, similar in color to ash. In the podzolized horizon, there is also a relative accumulation of the primary quartz included in its composition, since this mineral is resistant to chemical reactions. This whitish horizon is called eluvial or podzolic, and the horizon underlying it is called illuvial or inwash.
The intensity of the podzolic process (according to S.P. Yarkov) depends on the combination of soil formation conditions. The weaker the downward current of soil solutions, the less podzolized the soil, and this is associated with the ratio of annual precipitation and evaporation, the granulometric composition and physical properties of the soil, its position along the topography, the presence of forest litter, etc. In addition, for podzolization it is necessary periodic alternation of excess moisture (usually in spring) and drying (in summer) of the upper part of the forest soil profile. At the same time, as a result of the development of reduction processes in the forest litter, and sometimes under it, firstly, easily soluble ferrous compounds of iron and manganese, mobile forms of aluminum are formed, which easily migrate down with downward currents of soil solutions and, oxidizing in the illuvial horizon, are fixed in it. Where the noted conditions are absent, the podzolic process does not manifest itself even under coniferous forest due to the lack of redistribution of element content along the profile.
The course of the podzolic process also depends on the carbonate content of the parent rock. In the presence of free carbonates, the process does not proceed, since the acids involved in podzol formation are neutralized. Carbonates are both a natural geochemical barrier and prevent the removal of elements.
The severity of the podzolic process is greatly influenced by the composition of tree species. Under deciduous and broad-leaved forests, podzolization usually proceeds more slowly than under coniferous forests, due to the increased ash content of litter, which contains more alkali, alkaline earth and other elements. Podzolization intensifies if the ground cover under the forest is represented by mosses or lichens.
Along with podzolization, the genesis of podzolic soils is associated with lessivage. Lessivation is a complex process that includes mechanical shedding, a complex of physicochemical phenomena that cause dispersion of clay particles and their movement with the downward flow of soil solutions under the protection of mobile organic substances, aggregation and removal of iron (Melnikova, Kovenya, 1974). The process of loessification occurs more actively under deciduous forests with the participation of less acidic humus and mobile organic substances, with a slightly acidic and close to neutral reaction. Since the movement of silt through cracks and large pores without its destruction is observed in many soils, lessivage cannot be considered a specific process for the formation of the profile of podzolic soils only.
In addition to the indicated soil formation processes, the turf process occurs in all soil zones, including subzones of the taiga-forest zone. Its most significant feature is the accumulation of humus, plant nutrients and the creation of a water-resistant granular and lumpy structure in the upper soil horizon. Taking into account this characteristic, it should be noted that the subtypes of podzolic and gley-podzolic soils have very limited signs of the sod process in the form of a poorly developed humus layer (with coarse humus or fulvate-type humus) 1-5 cm thick.
The agricultural use of podzolic soils significantly disrupts natural soil formation, since plowing the land eliminates the influence of woody vegetation, forest litter, ground moss and lichen covers on soil-forming processes; as a result of the application of organic and mineral fertilizers, the content of humus and nutrients changes; liming eliminates high acidity and increases the biological activity of soils; when carrying out drainage measures, the water-air regime improves, etc. However, the lack of heat, and in the northern taiga subzone, light, remains a powerful cosmic factor limiting field agriculture.
Soddy-podzolic soils
Physicochemical characteristics. Soddy-podzolic soils are acidic; the acidity of the soils in the western regions of the southern taiga subzone of the European territory is determined by the cations H + and A1 3+, and in the eastern regions - mainly by H +; In the profile, the most acidic are the illuvial horizons.
The amount of exchangeable bases in the turf layer of loamy soils decreases from weakly podzolic species to strongly podzolic ones (from 20-25 to 10 mEq and lower). In the podzolic horizon the amount of exchangeable bases is the smallest, and in the illuvial horizon it is higher than in the turf layer. The degree of base saturation of soddy-podzolic soils is generally higher than that of subtypes of podzolic soils; however, there are many soddy, highly podzolic, low-humus soils in which the degree of base saturation is below 50%.
As a result of the development of planar water erosion, the composition and all properties of the arable horizon change significantly due to the plowing of the underlying horizons with their characteristic properties. At any degree of erosion, the arable layer is a mixture of horizons with a predominance of the mass of the main plowed horizon, which, as a rule, determines the properties of the cultivated layer.
The composition and properties of soddy-podzolic soils change significantly when cultivation methods are carried out: the soils lose their agronomically unfavorable properties and acquire new valuable qualities. In this case, the arable horizon changes most significantly.
Municipal educational institution
Gremyachevskaya secondary school
Geography lesson
in 8th grade on the topic:
Lesson developed by:
Mysyagina T.N.,
geography teacher
r.p. Gremyachevo, 2013
Lesson topic : “The main types of soils in Russia and patterns of their distribution”
Goals and objectives of the lesson:
To form an idea of the patterns of soil distribution on the territory of Russia, the characteristic features of soils in Russia.
Equipment:
Soil map, physical map, tables (soil types in Russia, soil sections).
During the classes
I. Organizing time
II. Repetition. Checking homework
Interrogation in groups of 4 people.
The work is carried out using cards: one student answers the questions on the card, three listen to the answer and check the correctness using the model.
Card questions:
1. What is soil called?
2. Name the conditions of soil formation.
3. Which of them are the main ones?
4. Who is the founder of soil science?
5.
How do soils differ in their mechanical composition?
b. Name the properties of soil.
7. Why is a loose structure important for soil?
8. Why are the soils of Russia diverse?
Answers to check using the sample:
1. Soil - the upper, loose, fertile layer of the earth's crust.
2. Soil formation conditions - maternal rock, plants, animals. Climate (warm and humid), relief, time.
3. The main ones are the parent rock, plants and animals, climate, microorganisms.
4. V.V. Dokuchaev.
5.
Sandy. Sandy loam, loamy, clayey.
6. The soil is fertile (contains humus, mineral salts, air, moisture), has a different mechanical composition, structure,
has soil horizons.
7. Loose soil contains oxygen and moisture. The best structure is grainy.
III. Learning new material
1. Studying soil types and their placement should begin with working on a soil map.
Teacher : Guys, look at the soil map of Russia. Name the soils.
Students : Arctic and tundra-gley, podzolic and sod-podzolic, gray forest, chernozems, chestnut, brown and gray-brown.
Teacher : It seems that the map is motley and the soils are located chaotically. Are there any patterns in the distribution of soils?
Let's take a short trip (using the soil map) from north to south across the East European Plain. Soils obey the law of latitudinal zonation, because we moved across the plain from north to south. In the mountains, soils change, following the law of vertical zonation from the foot to the top.
Alluvial soils in river floodplains, swamp soils, and volcanic soils violate the law of latitudinal zonation. The soil type corresponds to the vegetation type. "The soil is a mirror of the landscape."
2. Practical work No. 9. “Identification of the conditions of soil formation of the main zonal types of soils, assessment of their fertility.”
This practical work is carried out simultaneously with the teacher's explanation and under his guidance. During their work, students use soil and climate maps in the atlas, and diagrams of the structure of various soil profiles. As a result, students should have a table.
Natural area
Soil types
Soil properties
Soil formation conditions
Teacher : The soils of Russia are varied. Each type of vegetation has its own type of soil. We will trace the change of soils on the plain, moving from north to south.
The Arctic desert has low temperatures all year round and there is snow or ice on the surface, which cannot be the parent rock. Therefore, there is almost no soil in the Arctic desert. “Almost” because there are areas in the Arctic that are not occupied by snow and ice, and a thin layer of Arctic soils forms on them very slowly. To the south, in the tundra, the earth receives more heat, but summers are cool and short. Soil formation is also slowed down by permafrost, cooling the soil. The vegetation is represented by mosses and lichens and perennial shrubs. Under such vegetation, tundra-gley soils are formed. There is little humus in them, because the vegetation cover is not rich and the formation of humus is slowed down due to lack of heat.
Podzolic soils are formed in the taiga, and soddy-podzolic soils are formed in the southern taiga. When there is excessive moisture, the humus is washed out and an infertile leaching horizon is formed - podzol.
Teacher : Guys, why is there little humus in the taiga, although the vegetation of the taiga is much richer in biomass than the vegetation of the tundra and steppes?
Students: If there is excess moisture, the humus is washed out. Trees are perennial plants, and spruce, pine, and fir are evergreen, only larch sheds all its needles every year.
The teacher complements :
Needles are unfavorable plant litter, because contains resins. When rotting (and it is difficult), fulvic acids are formed, which are washed out of the soil, and also give it increased acidity. Therefore, the soils of the taiga are acidic.
In the Siberian taiga, soil formation is slowed down due to the underground “refrigerator” - permafrost. The soils here are taiga-permafrost. There is no leaching in these soils due to permafrost, which is a water-resistant layer.
Soddy-podzolic and gray forest soils are formed under mixed forests. Due to the greater amount of heat than in the taiga and more favorable plant litter, the soils of mixed and deciduous forests contain more humus.
The most fertile soils under steppe herbaceous vegetation are chernozems. They contain 10-12% humus, i.e. 10-12 times more than in taiga soils. Teacher : Guys, think about why the most fertile soils in Russia - chernozem, the “king of soils”, in the figurative expression of V.V. Dokuchaev, is under steppe vegetation?
Students : Grasses are the best plant litter, and annual litter at that. There is no washing, because moisture is insufficient, which contributes to the accumulation of humus.
Teacher : In a semi-desert, with poor moisture and sparse vegetation cover, saline brown and gray-brown soils are formed.
Soils do not always obey the law of latitudinal zonation.
Teacher : Think about where this law is violated?
Students : In the mountains there are altitudinal zones; each altitudinal zone has its own soil type.
At the end of the conversation, students should have a table:
Types and properties of soils in various natural zones
№ p/p
Natural area
Soil types
Soil properties
Soil formation conditions
1
Arctic
desert
Often absent or arctic
Very little
barren
Little warmth and vegetation
2
Tundra
Tundra-gley
Few
Low-power, have a layer of gley
Permafrost, little heat, waterlogging.
3
Forest zone
Taiga
Podzolic
Few
(1-2 %)
Washing, sour
k HC > 1, plant residues - needles
Taiga of Eastern Siberia
Taiga-permafrost
Few
Infertile, cold
Permafrost
Mixed
Sod-podzolic
More than in podzolic
More fertile
Spring flushing, more plant residues
Broadleaf forests
Gray forest
4-5 %
4
Steppes
Chernozems, chestnut
10-12 %
The most fertile soils
k uvl = 1 and 0.8; 0.9, a lot of plant residues annually, a lot of heat
5
Semi-deserts
Brown, gray-brown
Less humus
Soil salinization
Dry climate, sparse vegetation cover
k uvl< 0,5
IV. Consolidation
What soils form under forests? (podzolic, gray forest)
In which zone does the greatest accumulation of humus occur? (in the steppes)
Which soils are the most fertile? (chernozems)
Why is the accumulation of humus in forest zones decreasing? (soil leaching is in progress, ask > 1)
In which zone does salt accumulation occur? (semi-desert)
Why are the taiga soils in Eastern Siberia not podzolic, as in the European part, but taiga-permafrost? (in Eastern Siberia, permafrost prevents leaching and cools the soil)
V. Homework.
§ 26. Learn the main types of soils and their properties
Lesson topic: Zonal soil types. 8th grade.
Target: Formation of ideas about the zonal distribution of soils throughout the country and their characteristics.
Tasks:
Subject:
Give definitions of terms and concepts on the topic of the lesson;
Identify and name the features of zonal soil types;
Identify the relationship between zonal soil types and types of reclamation work;
Describe zonal soil types and soil resources;
Describe zonal soil types;
Mark geographic objects on a contour map.
Personal:
Formation of educational and cognitive interest in the study of geography;
Understanding and awareness of the characteristics of zonal soil types;
Using knowledge about zonal soil types in everyday life to preserve life and health;
Metasubject UUD:
Cognitive UUD:
Find reliable information in information sources;
Summarize thematic material;
Formulate conclusions;
Compose descriptions based on reliable sources of information;
Establish cause-and-effect relationships;
Compose a description of a phenomenon or object.
Regulatory UUD:
Determine the goal, problem in educational activities;
Choose means to achieve goals in a group and individually;
Plan educational activities;
Correct errors yourself.
Communication UUD:
Express your opinion;
Understand the other's position.
Personal UUD:
Reasonably evaluate your own and others’ actions in various situations;
Be aware of your emotions, adequately express and control them;
Understand the emotional state of others;
To recognize and prove oneself a citizen of Russia.
Lesson type: studying a new topic with practical work.
Equipment: textbook, atlas, projector, presentation.
UMK: Textbook Domogatskikh E.M., Alekseevsky N.I.
During the classes
I .Organizing time.
Greetings. Preparing for the lesson.
II .Homework survey.
III .Learning a new topic:
Open your notebook and write down the topic of the lesson: Zonal types of soils.
Based on the topic, what do you think we will study today. What questions will we consider? What should you learn in class today?
Today in class you will learn:
1. What is V.V. Dokuchaev famous for?
2. What types of soils are typical for the territory of Russia.
3. What is the peculiarity of soil placement.
4. Which soils have the greatest fertility.
5. What are soil resources.
6. How a person can restore soil.
And at the end of the lesson, try to find the answer to the questions:
1. Under the conditions of which natural zone should the most fertile soils be formed? Why?
2. Using the example of natural zones of taiga and steppes, prove that soils are a “mirror of landscapes”?
Open the soil map of Russia in the atlas. Name the soils. (sample answers). Are there any patterns in the distribution of soils? Let's take a journey along the soil map from north to south across the territory of the East European Plain. In the mountains, soils change, following the law of altitudinal zonation from the foot to the top. Soil types correspond to vegetation types.
At the same time, while explaining a new topic, we will perform practical work. Write in your notebook: Practical work No. 16 “Compilation of characteristics of zonal types of soils and identification of the conditions for their soil formation.” We will do the work in the form of drawing up a table.
Types and properties of soils in various natural zones
| Natural area | Soil types | Soil properties | Soil formation conditions |
|
| 1 Arctic desert | often absent or arctic | very few | Not fertile | Little warmth and vegetation |
| 2. Tundra | tundra-gley | few | Low-power, have a layer of gley | Permafrost, waterlogging, lack of oxygen, their thickness does not exceed a few centimeters. |
| Forests | They occupy more than half of our territory. Several types of forest soils form under forests. |
|||
| 3. Taiga of the East European Plain | podzolic under northern taiga forests | little 1-2% When there is excessive moisture, the soil is washed out and podzol is formed. | Washing, acidic, low-fertility | High humidity, acidic, plant remains - pine needles |
| 4.Taiga of Eastern Siberia | taiga-permafrost | few | Infertile, cold | Permafrost, soil formation is slow. There is no leaching in these soils. |
| 5. Mixed | sod-podzolic | more than in podzolic | More fertile | |
| 6. Broadleaf | forest gray | 4-5% | More fertile | Spring flushing, more plant residues |
| 7.Steppes | chernozems, chestnut | 10-12% | The most fertile soils, granular structure | Lots of plant residues every year, lots of heat |
| 8. Semi-deserts | brown semi-desert, gray-brown, and sometimes salt marshes are formed. Increased salt content. | There is not much humus in these soils, but these soils are dry, dense and structureless. | Soil salinization. This reduces fertility. | Dry climate, sparse vegetation, lack of moisture. With artificial irrigation of the land, high yields can be obtained. |
Conclusion: (independently) Soil formation processes largely depend on the climatic conditions of the area. The climate naturally changes from north to south. Soil changes are also taking place in this direction. This was first proven by the Russian scientist V.V. Dokuchaev more than 100 years ago. He established the presence of zonal soil types, which naturally replace each other from north to south. They correspond to the main natural areas of our country.
Soil resources. Read in the textbook on pages 181-182
IY . Consolidation
1. What are soil resources? (soils capable of supporting plant development.
2. What are the main destroyers of the soil layer? (water and wind)
3. What is erosion? Types of erosion.
4. What is land reclamation?
5. What is reclamation?
6. Why is it necessary to protect the soil? And how should they be protected?
7. Why does soil fertility first increase and then decrease when moving from north to south?
At the beginning of the lesson, I asked you a question that I asked you to answer by the end of our lesson.
In what natural zone should the most fertile soils be formed? Why? (suggested answer)
Chernozem soils have record fertility. The thickness of the humus horizon can exceed 1 m. There is enough heat, moisture and humus here.
Using the example of natural zones of taiga and steppes, prove that soils are a “mirror of landscapes”? (sample answer)
Under coniferous vegetation there are podzolic soils, under grasses there are chernozems.
Y .Reflection.
1. Everything was clear to you when studying the topic and doing practical work.
2. Did you complete the task?
3. Who was the most active during the lesson today?
4 Who knows what didn’t work out and has questions?
YI . Grading. Everyone will be graded for completing practical work.
YII . Homework. Paragraph 29, repeat 28
Creative task. .Write an essay on topic 1. “Is it possible to create artificial soil.”
2. What V.V. Dokuchaev strived for all his life.
