The following large geomorphological structures stand out in the relief: the plains of the Cis-Urals, the Ural Mountains, the Trans-Ural peneplain and the plains of the Turgai plateau. The main river is the Ural with tributaries. The region is located mainly in the steppe zone, forests occupy about 4% of the territory. The territory of the region is 124 thousand km2 (0.7% of the territory of the Russian Federation). The population is 2224 thousand people, urban - 61%. Population density - 18 people. per 1 km2.

The Orenburg region was formed on December 7, 1934. From December 26, 1938 to December 4, 1957, it was called the Chkalov region. The distance from the regional center of Orenburg to Moscow is 1478 km. Included in the Volga Federal District.

It occupies a vast territory in the southeastern outskirts of the European part of Russia. The total length of the borders of the region is about 3700 km. The territory of the region is stretched from west to east for 750 km. The extreme northern and southern points of the region are 435 km apart in latitude, while at the narrowest point the distance between the northern and southern borders of the region is only 50 km. The southern border of the region for about 1670 km is the border between Kazakhstan and Russia. Almost the entire northern border of the region falls on Bashkiria, only in the extreme northwest Tatarstan adjoins the region, and in the northeast - the Chelyabinsk region. In the west it borders on the Samara region, and the extreme western point joins the Saratov region. The region is located in two parts of the world, Europe and Asia. Historically, the border between them within the region is drawn along the Ural River. However, the physical-geographical boundary runs along the eastern foot of the Ural Range, Mukhodzhar and the Emba River.

In the west and east of the region, the relief is characterized by leveled interfluves and gentle slopes with low remnant ridges, and in the central part, in the interfluve of the B. Ik and Sakmara, it is a lowland. The highest point of the region on the Small Nakas Ridge in the Tulgansky district has a mark of 667.8 m, the lowest point is the edge of the river. Ural at the village of Early in the Tashlinsky district - 39.7 m above sea level.

The following large geomorphological structures stand out in the relief: the plains of the Cis-Urals, the Ural Mountains, the Trans-Ural peneplain and the plains of the Turgai plateau.

The main river is the Ural with tributaries. The region is located mainly in the steppe zone, forests occupy about 4% of the territory. The territory of the region is 124 thousand km2 (0.7% of the territory of the Russian Federation). The population is 2224 thousand people, urban - 61%. Population density - 18 people. per 1 km2. Live: Russians, Tatars, Ukrainians, Kazakhs, Mordovians, Bashkirs, Germans, Chuvashs, Belarusians.

In total there are 12 cities in the republic. The largest of them are: Orenburg, Orsk, Novotroitsk, Buzuluk, Buguruslan.

In ancient times nomadic tribes of Bashkirs and Kazakhs lived on the territory of the region. In the XIII century. these lands were conquered by the Mongol-Tatars and included in the Golden Horde. The penetration of Russians into the Orenburg steppes is associated with the beginning of the process of joining the territory of Kazakhstan to Russia in the 18th century. Here the Orenburg Cossack army was formed, which served as a border guard on the southeastern borders of the Russian Empire. In 1773-1775. the region was one of the main bases of the rebel army of E. Pugachev. By the end of the XVIII century. the process of settling the Orenburg lands by Russians intensified, and this territory became firmly part of Russia.

Orenburg was originally founded in 1735 as a fortress at the confluence of the river. Or in the river. Yaik (modern Ural River). In 1740 the city was founded in a new place - on Krasnaya Gora (downstream along the Yaik River) with the preservation of the former name; the old city was called the Orsk fortress (modern city of Orsk). In 1743 the city was moved for the third time, to the West, to the site of the Berd fortress (founded in 1737). The city on Krasnaya Gora continued to exist under the name Krasnogorsk fortress (now the village of Krasnogor, Saraktash region). In the 18th - 1st half of the 19th centuries. Orenburg is the main fortress of the Orenburg military border line (abolished in 1862). From 1744 the center of the Orenburg province, from 1782 - the Ufa governorship, at the same time the residence of the head of the Orenburg region; in 1796-1802 and since 1865 again the provincial center. Since 1748 the military and administrative center of the Orenburg Cossack army. From October 5, 1773 to March 23, 1774, it was besieged by the army of Yemelyan Pugachev. In 1850-81 Orenburg was the center of the general government; until 1868 there were institutions in charge of border affairs, the administration of the Kazakhs of the Small Zhuz; since 1868 the seat of the governor of the Turgai region. It was a major center of Russian trade with Kazakhstan and Central Asia; in Orenburg there was the Exchange Yard (built in 1749-54) and Gostiny Dvor, border customs (abolished in 1868). Industry (mainly flour-grinding, lard-making, leather-processing, and oil-pressing) began to develop with the construction of the Samara-Orenburg railway in 1877. In 1905, the Orenburg-Tashkent railway was built and the main railways and repair shops were opened. The city became a major trade and distribution center for livestock and meat (in 1894 city central slaughterhouses were opened, and from 1880 the export of fresh and frozen meat began), the so-called. Siberian ghee, lard, leather, wool, goat down; sawmilling and woodworking industries are developing. In 1920-25 Orenburg - the capital of the Kirghiz ASSR, since 1934 - the center of the Orenburg region. In 1938-57 it was named Chkalov. Orenburg was a place of political exile; poets T.G. Shevchenko, A. I. Pleshcheev, composer A. A. Alyabiev.

The region's economy combines developed industrial and agricultural production. The main industries are ferrous and non-ferrous metallurgy, mechanical engineering and metalworking. An important place is occupied by the oil and gas, light and food industries. Copper, nickel, cobalt and gold are mined. One of the largest metallurgical plants in Russia operates in Novotroitsk. Copper is smelted in Mednogorsk, nickel and cobalt are smelted in Orsk. Large factories operate - heavy engineering (Orsk, Buzuluk), electrical products (Mednogorsk), agricultural engineering (Buzuluk). The oil refining and chemical industries are developed (fuel, oils, sulfur, nitrogen fertilizers, rubber products). Large production of building materials. A number of food and light industry enterprises are of national importance. Orenburg downy shawls have long been famous.

Agricultural land covers 87% of the region. The leading crop is spring wheat, in addition to it, rye, millet, sunflower, potatoes, vegetables, watermelons, and melons are grown. A significant place belongs to horticulture. Cattle, pigs, goats (including downy Orenburg breeds), sheep, and poultry are bred.

Main railway lines: Samara - Orenburg, Buguruslan - Ufa, Orsk - Kartaly - Chelyabinsk, Orsk - Magnitogorsk. The network of highways is developed. Air lines connect the center of the region with other major cities of Russia.

An important transport center (3 railway lines, 3 highways, airport) is the city of Orenburg.

The leading industries of the city are mechanical engineering and metalworking. Machine tools, tools, drilling equipment, machines for the food industry, electromechanical and refrigeration equipment, spare parts for tractors and combines are produced. There are large factories for rubber products, petroleum oils and for the production of building materials. There are many food industry enterprises (a large meat-packing plant stands out), leather and footwear, clothing and knitwear production is developed. A large factory for silk fabrics and a factory for hand-made and factory dressing of the well-known Orenburg downy shawls.

Russian Civilization

Geographical position. The territory of the region covers the southeastern outskirts of the East European Plain, the southern tip of the Urals and the southern Trans-Urals. The Orenburg region borders in the west and northwest - with the Samara region, in the north - with the Republic of Tatarstan, the Republic of Bashkortostan and the Chelyabinsk region, in the south with the Republic of Kazakhstan (1875 km).

The territory of the region extends from west to east for 755 km, from north to south in the western part for 320 km, in the central part for 51 km and in the eastern part for 215 km. The total length of the borders is 3,700 km. The area of ​​the Orenburg region is 124 thousand km. This is one of the largest regions of the Russian Federation.

AT In the city of Orenburg, on the left bank of the Ural River, there is the first sign in Russia denoting the border between Europe and Asia (the "Europe-Asia" obelisk).

Climate The Orenburg region is sharply continental, which is explained by the significant remoteness of the region from the oceans and seas. An indicator of the continentality of the climate is a large amplitude of fluctuations in average air temperatures, which in the Orenburg region reaches 34-38 degrees Celsius. In this regard, there is a lack of precipitation, the annual amount of which ranges from 450 mm in the northwest to 350 mm in the south and southeast of the region. About 60-70% of the annual precipitation falls on the warm period. Durationthe occurrence of snow cover ranges from 135 days in the south to 154 days in the north of the region. The depth of soil freezing varies from 170 cm in the northwest to 200 cm in the east.

Population.The population of the region, according to Rosstat, is 1,994,762 people. (2016). Population density - 16.13 people / km 2 (2016). Urban population - 60.08% (2015).The region is multinational and non-conflict, historical experience of tolerance of coexistence of different cultural and religious groups of the population has been accumulated.

The Orenburg region is part of the Volga Federal District and is an important industrial and agricultural region of Russia. The Orenburg region has a large diversified industry, in which mining and heavy industries stand out; intensive agriculture. The leading intersectoral complexes are fuel and energy, production of structural materials, machine-building and agro-industrial. The Orenburg region includes 12 cities and 35 rural centers.

Agriculture. Livestock breeding of meat and dairy direction, poultry farming, sheep breeding and goat breeding have been developed in the region. Fur-bearing and beekeeping are represented among other branches of animal husbandry in the region.

The Orenburg region ranks second in the Russian Federation in terms of arable land (more than 6 million hectares). The region mainly grows spring and winter wheat (the Orenburg region ranks first in the Russian Federation in the cultivation of durum wheat), winter triticale, oats, spring barley, cereals, corn, sunflower, peas, soybeans, chickpeas, sugar beet, spring rapeseed, annual and perennial herbs, potatoes, vegetables and gourds.

Orenburg region- one of the largest regions of Russia, located in the southeast of Russia, at the junction of Europe and Asia, borders on the Republics of Tatarstan and Bashkortostan, Samara, Saratov and Chelyabinsk regions and the Republic of Kazakhstan. The absence of high mountain ranges and the location in the center of the vast Eurasian continent form a sharply continental climate in the region. On the territory of the Orenburg region, there are landscapes of the forest-steppe of central Russia, the steppes of the Trans-Volga and Turgay, the wooded lowlands of the Southern Urals, and the pine-birch forest-steppe of Western Siberia.

To a person who is little familiar with, his landscape appears in the form of monotonous and dull steppes and fields. But for those who have been in the region, it is a land of rare beauty, an exceptional variety of landscapes, and the unique color of local nature. Hilly "Aksakov forest-steppe" with birch groves, oak forests, linden forests, steppe ridges, wooded spurs, miniature ridges, hills and gorges of the Guberlinsky upland. All of these landscapes are Orenburg region.

In the south of the region, in the Sol-Iletsk district - prevails, in the north in the Tyulgan region - and, in the central and eastern parts of the region - endless.

Diversity and Contrast nature of the Orenburg region is explained by the fact that the territory contains the limits of the distribution of many species of flora and fauna, and also the border between Europe and Asia, the steppe and the forest-steppe.

Orenburg region located mainly within two physical and geographical countries - the Russian Plain and. The border between them runs along the western outskirts of the Maly Nakas ridge, then goes parallel to the Bolshoi Ik valley, crosses the Sakmara-Ural interfluve along the Kondurovka-Burli mouth line and stretches southeast, to the upper reaches of the Burli River. This is the main landscape boundary of the region. To the west of it, piedmont hilly and then flat areas predominate, connected with the geological basis of the Russian Plain and its Cis-Ural trough. To the east, low-mountain and low-mountain areas of the folded Urals are developed, changing in the Sarah region and east of the high plain (peneplain) on the crystalline foundation of the destroyed Ural Mountains.

The second important natural boundary of the region is the boundary between the steppe and forest-steppe landscape zones. It is primarily due to climatic features and is expressed in the change of zonal types of vegetation and soil cover. The presence of forests on watersheds does not serve as a basis for drawing this boundary. The northern limit of the steppe zone of the region is marked along the line of the rivers Maly Kinel - Bolshoy Kinel - the source of the Salmysh River - the mouth of the Bolshaya Yushatyr River - the lower reaches of the Bolshoy Ik River - the northern outskirts of the Sarinsky Plateau.

Thus, if we draw on the main landscape boundaries, we will get the most general scheme of the natural zoning of its territory. In the north-west of the region, the Zavolzhsko-Priduralsky forest-steppe elevated province - "Aksakov forest-steppe" - will stand apart. The west and southwest of the region are formed. As you move south, it drops in steps towards the Caspian Sea. To the east of the Salmysh River, it gradually passes into the Cis-Urals. To the south of the valley of the middle reaches is the Poduralsky Syrt (the interfluve of the Urals and the Ilek). In the mountainous part of the region, the South Ural low-mountain forest-steppe province stands out (it includes Maly Nakas, the right bank and the northwestern part of the Sarinsky plateau). This wooded region is often referred to as " Orenburg Switzerland". Most of the Sarinsky plateau, and the small hills to the south form the South Ural low-mountain steppe province. Almost the entire east is part of the South Transural (Ural-Tobolsk) high-plain steppe province. Only the extreme southeast of the region belongs to the West Turgai steppe province of the Turgai canteen of the country.

The distinguished physiographic provinces are also heterogeneous. They trace the subzones of the northern, typical and southern steppes. But landscape areas most fully reflect the diversity of the nature of the Orenburg region. The structure of natural areas is formed by the so-called typological landscape complexes - types of terrain and tracts that can be considered natural lands of the region.

Terrain types of the Orenburg region

The main types of terrain in the Orenburg region are: floodplain, above-floodplain-terrace, valley-beam, near-valley-upland, watershed-upland, syrt-hilly, hilly-sandy and low-mountain-ridge.

floodplain type The area is confined to areas of river valleys flooded during the spring flood. It is distributed in all provinces of the region, but is most developed in and in the Cis-Urals (floodplains, Samara, Ilek, etc.). There are three levels of floodplain: lower, middle and upper. Despite the insignificant area of ​​distribution, the floodplain type of terrain plays an important economic role. The region's forests and the best hayfields are concentrated here. The oxbow lakes are of great fishery importance. Plowed areas of the floodplain are used for gardening, vegetable growing and melon growing. Above floodplain terraced the type of locality is developed along the valleys of all significant rivers of the Orenburg region. In the Samara basin and from Belyaevka to Ilek, terraces above the floodplain occupy, as a rule, the left-bank parts of the valleys. Along the Ilek and downstream of Rassypnaya, they are common on the right bank.

Valley-beam the terrain type combines the primary slopes of river valleys, gullies and slopes adjacent to them. It is distributed in all provinces of the region. The natural structure of the valley-beam complex is distinguished by great diversity and dynamism. The processes of planar and linear erosion and landslide formation proceed intensively here. The valley and ravine slopes are usually plowed up. The upper reaches of the beams are covered with oak-birch and aspen forests. Narrow ribbons of black alders wind in deep logs along the streams. Many other unique natural monuments (picturesque cliffs, rocks, caves, springs, etc.) are confined to this type of area.

Modern natural structure valley flats completely consists of anthropogenic tracts: field (agricultural), silvicultural, residential, road. The valley plains are the most valuable arable land, so the main part of the grain crops of the Orenburg region is concentrated here.

Watershed-upland the terrain type is confined to flat areas of high watersheds preserved from erosion. It is distributed in places in the Cis-Urals, on the Sarinsky and Ural-Tobolsk plateaus. Watershed plakors are characterized by deep (up to 35 m) occurrence of groundwater. On the watershed uplands and the Sarinsky plateau, there are tracts of endorheic depressions with a depth of 1-5 meters and a diameter of up to several hundred meters.

Syrt-hilly type of terrain - a kind of landscape endemic of the interfluves of the rivers of the Volga and Ural basins. It is a combination of narrow convex saddle watersheds with a large number of outliers - shikhans, cones, hills, where slabs of Triassic sandstones or fields of Jurassic pebbles are exposed. Blocks and fragments of quartzite-like perforated sandstones and conglomerates, sometimes reaching 4-7 meters in diameter, are scattered on their surface.

Hilly-sandy The type of locality is massifs of cumulus sands, not fixed or weakly fixed by vegetation, and most often distributed on the right-bank floodplain terraces, high floodplains, and sides of river valleys. Hilly sands are original natural complexes superimposed on the primary types of terrain. In the Orenburg region, a hilly-sandy type of terrain is developed on the right banks of Samara, the Urals, Ilek, on the interfluve of the Ilek and Malaya Khobda, in the lower reaches of the Kumak and Ori rivers. The average thickness of eolian sand deposits is from 2 to 8 meters. Due to winding, on the surface of the sandy massifs, hollows of blowing and sandy mounds (dunes) up to 5-6 meters high were formed. Sand contributes to the good penetration of precipitation and melt water into the depths and the formation of a stable groundwater horizon at a depth of 1 to 4 meters.

Low mountain ridge the type of terrain is widespread in the mountainous part of the Orenburg region (Small Nakas, Ziyanchurin ridges, Kuvandyk mountains and others). It is a combination of linearly elongated ridges up to 400-600 meters high and inter-ridge depressions dissected by a river network.

In the Trans-Urals, in addition to those described above, interfluve undrained and interfluve, rock-remnant types of localities are common. In the extreme south-east of the Orenburg region, within the limits of the Turgai canteen, the countries have developed lake-terrace and coastal-lake.

Locality types are divided into various subtypes and variants associated with the features of the relief and the composition of the constituent rocks. For each type of terrain, natural combinations of types are characteristic. tracts.

tract- an old Russian term, widely known in the colloquial language. By it is usually meant something remarkable piece of terrain. We call tracts lily-of-the-valley oak groves, sedge forests, pine forests, oxbow lakes, thickets of steppe shrubs, meadow-steppe depressions, shikhans, chalk hills, and so on, that is, everything that determines the face of the landscape.

And in addition to the above, I would like to note that if you need to book a hotel in Orenburg without a commission, for an unforgettable vacation in our region, right now you can do it on the website of our partners.

If you look at the physical map of the Orenburg region, you can see a very different color scheme.

The Orenburg region is a land of amazing diversity of natural conditions.

Almost the entire western part of the region belongs to the General Syrt (Syrt in Kazakh means a high place). The highest point is Mount Bear forehead (Arapova mountain) - 405 m. There are many sharp or flat-topped "cones" - shikhans on the Common Syrt. The slopes of the valleys are cut by gullies and ravines.

In the extreme north-west of the region, the Bugulma-Belebeevskaya Upland adjoins the General Syrt. In the south-west, it borders on the plain of the Caspian lowland.

In the Cis-Ural part, the Common Syrt takes on the appearance of low mountains, among which the Goat Mountains up to 487 m high and the Small Nakas Range with heights from 500 to 667 m stand out.

Along the Ural River, high jagged rocks of the Guberlinsky Mountains stretch from the village. Ilyinka to the village. Akkermanovka. They rise above sea level by 400 - 430 m.

All the way through the Guberlinsky mountains, picturesque mountain rivers flow into the channel of the Urals: on the right - Guberlya with Chebakla, Kinderlya (Kinoplyanka), and on the left - Aytuarka and Alimbet.

After the confluence of the Alimbet, the banks of the Urals gradually become gentle. Behind the rocky mountains. Hills stretched along the left and right banks. The farther to the west, the gentler the hills. Below the mouth of the Burli, the left bank becomes low and flat - a wide strip of near-ural left-bank terraces begins, which stretches to the Ilek, interrupted only at the mouth of the Berdyanka. And low mountain ranges and hills approach the right bank: Mayachnaya, Verblyuzhka, Alabaital, Giryal, Krasnaya Gora, Alabaster (Orenburg region).

Below Orenburg, having accepted Sakmara, the Urals, keeping the western direction, gradually deviate to the south. From the north, it is crowded by the steep cliffs of the General Syrt, composed of dense red sandstones. The highest of them - Mount Goryun (278 m) - is located near the village of Rychkovki (Orenburg region).

In front of Ilek, the riverbed splits into two branches, called Strife, forming a wooded island.

In the confluence of the Irtek, chalk mountains approach the Ural channel, forming high ravines overgrown with oak, birch, and elm. Below the chalk mountains, the Utva flows into the Urals on the left. Further, past the village of Early, the Urals go to the territory of Kazakhstan.

The eastern part of the region lies to the east of the Ural River valley and is represented by the Ural-Tobolsk plateau, the Orsk plain and, in the extreme east, the Turgai table country. This area is a wide soft-undulating elevated plain. The average heights here range from 300 to 350m. There are separate "mountains" - Mt. Kosshoka (417m), shallow lakes ("steppe saucers") - Svetlinsky lakes are often found.

The Ilek plateau is located in the south of the region. The slopes of this plateau are gently sloping and often turn into shallow hills. The highest point of this plateau is Bazarbay (331m).

assignment for the student.

What does the area you live in look like?

Learn to show different geographical points on the map of the region, relative to the sides of the horizon.

Task for adults.

Make a "correspondence" journey with the child on the physical map of the area, moving from north to south or from west to east, "choosing" the appropriate transport.

Introduction

1. Natural conditions

1.2 Relief

3 Vegetation

1.4 Soil formation factors

Soil-geographical zoning of the Orenburg region

1 Soil zoning

2 Soil belts, regions, zones, provinces, districts

Soil genesis

3.1 Chernozems

3.1.1 Leached chernozems

1.2 Southern chernozems

3.1.3 Ordinary chernozems

3.2 Dark chestnut soils

3 Gray forest soils

Bibliography

Introduction

Soil geography is a branch of soil science that studies the patterns of distribution of soils on the Earth's surface for the purpose of soil-geographical zoning, it is divided into general and regional. The general geography of soils studies the factors of soil formation and the most general laws of the geographical distribution of soils, the types of structure of the soil cover; regional soil geography - issues of zoning and deals with the description of the soil cover of individual regions. The main method of soil geography is comparative-geographical, with the help of which the geographical distribution of soils is studied in connection with the factors of soil formation. Soil mapping is widely used.

Soil geography arose at the end of the 19th century. and developed under the influence of the demands of agricultural production, the need for an inventory of soils and their assessment. The foundations of soil geography in Russia were laid by V.V. Dokuchaev, who established the relationship between the soil and the natural factors that form it, showed the patterns of soil distribution and developed a method for the profile study of soils in conjunction with soil formation factors.

The Orenburg region occupies a special place in soil geography. Located within the forest-steppe and steppe natural zones, the Orenburg region has rich soil resources. The soil and climatic conditions are favorable for the cultivation of grain and industrial crops, as a result of which the chernozem steppes have all been plowed up. 51% of the territory is occupied by arable land. The degree of plowing was the highest in Russia. The forests of the region, including the wonderful natural monument - Buzuluk forest, occupy only 4% of the territory.

Soils are characterized by latitudinal zonality. Soil types and subtypes successively change from meadow steppes to desert steppes: typical, ordinary and southern chernozems, dark chestnut, chestnut and light chestnut soils.

The regular change in soil types is associated with the action of three leading processes of steppe soil formation: humus accumulation, carbonatization, and solonetzization.

The influence of the process of carbonatization on steppe soil formation sharply increases to the south. The farther to the south of the steppe zone, the more pronounced is the process of alkalinization, which prevents the process of humus accumulation. In the desert steppe subzone, light chestnut soils developed on clayey rocks are almost all solonetzic.

Chernozems occupy 79% of the region's arable land structure, dark chestnut soil subtype - 16%, gray forest soils - 4% of the area. Among the chernozems, the largest area is occupied by southern chernozems - 44%, ordinary - 26%, typical and leached - 9%. In the subzones of southern and ordinary chernozems, 14 and 7% of the area, respectively, are occupied by solonetzes. In the subzone of dark chestnut soils, the area of ​​solonetzes is 36%.

Underdeveloped and eroded soils occupy 17% of their area among typical chernozems, 39% of ordinary chernozems, almost 50% of southern ones, and 22% of its area in the subzone of dark chestnut soils. The subzone of ordinary chernozems has been plowed up by 74%, southern - by 52%, dark chestnut soils - by 43%.

The issue of preserving the soil cover from water and wind erosion, increasing crop yields is an acute issue. At the same time, the creation of protective forest plantations was sharply reduced.

1. Natural terms

1.1 Climate

The territory of the Orenburg region has favorable conditions in terms of natural and climatic conditions, and the average annual values ​​of its climatic parameters are classified as "low" and are favorable for the conditions of dispersion of harmful substances in the atmosphere.

The territory of the region lies in the depths of the continent at a considerable distance from the oceans. The continental position strongly affects the climate and soil and vegetation cover of the Orenburg region.

The climate of the region is sharply continental, which is explained by its considerable remoteness from the seas and proximity to the semi-deserts of Kazakhstan. The climatic conditions of the surveyed area are characterized by a large amplitude of fluctuations in annual and daily temperatures, strong winds, short spring and long autumn periods. The average monthly air temperature of the coldest month of January is 13.1 0C, and the hottest month of July +22.1 0C. Winter lasts 4.5 months. The minimum winter temperature reaches minus 40-44 0C. Summer has about the same duration with a maximum temperature of plus 44 0FROM

The wind is extremely variable, both in direction and speed. On average, only 45 days a year are windless.

The direction of the wind and calm, according to long-term observations, is per year in%: SV-8, S-10, V-20, SE-9, S-12, SW-15, W-18, NW-10, calm-3, 9. The wind speed, the excess of which for this region is 5%, reaches 9 m/s. In winter, east and southwest winds prevail, in summer east and west. The average wind speed is 4.0 m/s. The survey area is characterized by particularly strong winds in winter during snowstorms and in summer during periods characterized by low relative humidity and high average daily temperatures.

Such a wind regime and the flat nature of the terrain contribute to the removal of pollutants.

The growing season is about 180 days. A characteristic feature of the region's climate is its aridity. Summer precipitation does not have time to soak into the soil, as high air temperatures contribute to its rapid evaporation.

Precipitation in the region is distributed unevenly. Their number decreases from the northwest (450 mm per year) to the southeast (260 mm per year). The maximum amount of precipitation falls on the Small Nakas Ridge (up to 550 mm per year). Approximately 60-70% of the annual precipitation falls on the warm period, which somewhat smoothes the aridity of the climate.

The low moisture supply of the Orenburg steppes often leads to drought. Over the past century, in the northwestern regions of the region, severe and medium droughts have been observed once every 3-4 years, and in the southern regions once every two to three years.

The height difference does not exceed 50 m per 1 km. Few foggy days. Air humidity is characterized by one of the main indicators of relative humidity, the lowest value of which is observed in the warm season with a minimum in May, and the highest - in November-December and March.

Blizzards are most often associated with the passage of western and southern cyclones, bringing stormy winds, heavy and sleet snow, and sometimes rain, in the middle of winter. The number of days with blizzards varies here from 26 to 49 days a year. Blizzards are observed regularly from November to March, and their largest number is observed in January. Thunderstorms occur on average per year for 21-29 days. The greatest development of thunderstorm activity is observed in July.

In Orenburg, the amplitude of atmospheric pressure is from 14.6 Mb. The average minimum pressure measured in July is 995.6 Mb, the average maximum in December is 1010.2 Mb.

The total duration of sunshine is 2198 hours. The greatest duration is noted in July (322 hours), the smallest - in December (55 hours). On average, there are 73 days without sun per year.

1.2 Relief

The Orenburg region is distinguished by a variety of relief. Its western part is located within the southeastern margin of the East European Plain. Here are the heights of Bugulma-Belebeevskaya and General Syrt, from the south comes the Caspian lowland. The east of the region is located within the southern spurs of the Ural Mountains, the Trans-Ural and Turgai plateaus. The absolute heights of the surface range from 39 m in the valley of the Ural River at its intersection with the southern border of the region to 667 m on the Nakas Ridge.

The surface of the Orenburg region is predominantly wavy-flat, but the relief of its individual parts is distinguished by significant features. The western, or Ural part, stretching from the borders of the Samara region to the valleys of the Bolshoi Ik and Kiyaly-Burtya rivers, is an elevated syrt plain with heights from 200 to 400 meters above sea level. Characteristic for it is the direction of river valleys from the southeast to the northwest. Only in the extreme south is there a general slope of the syrt plain towards the Caspian lowland.

Almost in the middle of the Urals rises the system of ridges of the General Syrt, which has the most diverse structure. The northern slopes of the ridges are in most cases gentle, imperceptibly merge with the slopes of valleys, rivers and gullies. The southern slopes are very steep, often steep. The surface of the syrts is either wavy or flat. The central part of the region is occupied by the folded zone of the southern spurs of the Ural Mountains. It is located east of the Bolshoy Ik and Kiyaly-Burti valleys to the meridional part of the Ural River valley and is a plateau strongly dissected by deeply incised river valleys.

Farther to the east, the terrain acquires an increasingly complex hilly-hilly relief. From the village of Ilyinka, the Guberlinsky Mountains begin. Steep hills 50-80 meters high prevail here. They are either sharply isolated or grouped into short ridges. Narrow and deeply incised valleys of the Guberli and Podgornaya rivers with their tributaries, as well as gullies and ravines, often cut through the ridges and highlight elevations on them. All this creates the impression of a mountainous landscape; however, the height of the mountains does not exceed 430 meters. In the north, the Guberlinsky mountains pass into the steppe of the hills. In the south they continue beyond the Ural valley.

The eastern part of the region is called the Ural-Tobolsk plateau. It is a wide, gently undulating, elevated plain. The average height of the plateau ranges from 300 to 350 meters, but in some places, for example, in the northwest, heights reach 400 meters or more.

The mostly calm, flat nature of the surface of the Orenburg region makes it suitable for the development of agricultural production.

1.3 Vegetation

Dry-loving herbaceous vegetation dominates in the Orenburg region. Forests occupy only 4% of the territory. Most forests are in the northwest. Here the forest grows not only in river valleys, but also on flat watersheds. To the south, due to the dryness of the climate, the forest gradually disappears from the watersheds. Forests cover mainly the tops of the syrts and river banks. In terms of landscape, the north-west of the region, combining meadow steppes and insular forests, belongs to the forest-steppe. Island forests are represented by broad-leaved species - oak, maple, elm. The oak forests are dominated by linden, smooth elm and rough elm (elm), Norway maple, mountain ash and hazel. Of the small-leaved species, birch is often found, forming swampy pegs. Many forests have been reduced. The reduction of forests is due to fires, deforestation and grazing. Meadow steppes are almost completely plowed up. Rare preserved areas of the steppes are formed by colorful meadow herbs and steppe grasses.

The forest-steppe of hilly plains is replaced in the Cis-Urals by mountain forest-steppe. The mountain forest-steppe is expressed on the Maly Nakas ridge and in the low mountains of the north of the Kuvandyk region. The upland forests are dominated by oak, elm and birch.

But it is not the forests that determine the appearance of the region: the boundless steppe dominates. To the south of the forest-steppe zone, the forest gradually leaves the syrt peaks for river valleys, gullies and ravines. Due to the dryness of the climate, oak and linden do not penetrate south of the Ural valley. The Ilek valley is characterized by black alder groves, dark and damp, with myriads of mosquitoes. Despite the apparent uniformity, the steppe vegetation noticeably changes when moving from north to south. Forb-meadow steppes of the north-west of the region include rich colorful forbs, which suppresses cereal vegetation. Among the grasses are feather grass and bluegrass. In the meadow steppes, there are 80-100 plant species per hectare with a hay productivity of 25-40 q/ha.

To the south of Bolshoy Kinel, meadow steppes give way to forb-feather grass steppes. The farther to the south, the stronger the dryness of the climate impoverishes the forbs and increases the proportion of steppe grasses. In the forb-grass steppes, forbs and cereals share the primacy in the steppe herbage. In the Suunduk basin in the east of the region, birch woods and pine forests are scattered among the forb-feather grass steppe. Despite a small amount of precipitation, granites contribute to the growth of pine. Dense granite aquiclude creates conditions for pine forests, as in a flower pot.

South of the river Samara, south and east of the river. Ural, dominance passes to the fescue-feather grass steppe. The herbs are very poor.

The southernmost steppes in the Orenburg region are feather grass and wormwood. They are common in the river basin. Chagan, south of the valleys of the Ilek and Kumak rivers. Both steppe and semi-desert plant species are found here. The feather grass-wormwood steppes are characterized by sparseness and spotting of the herbage. Because of the spotting among the Yaitsky Cossacks, the southern steppe was called the “chubaraya steppe”.

Thus, from north to south in the Orenburg region, in accordance with the natural zonality, meadow, forb-feather grass, fescue-feather grass and feather-grass-wormwood steppes replace each other. In the southern and eastern regions of the region, saline steppes and solonchak meadows are developed on saline soils.

The diversity of plant communities led to the formation of a rich flora. This is facilitated by the geographical position of the region at the junction of European, Siberian and Turanian elements of flora, as well as the presence of endemic and relict plants. The total list of flowering plants in the region exceeds one and a half thousand species. Of the cereals, the Red Book list includes the most beautiful feather grass, pinnate, Zalessky, pubescent and thin-leaved hard-leaved.

The Red Book lists 8 species of orchids growing in the region, among them the large-flowered slipper, Lezel's liparis and helmet-bearing orchis. From the lily family, this list includes Schrenk's tulip and Russian hazel grouse. The Red Book includes Korzhinsky's licorice, large-flowered, silver-leaved, Razumovsky's kopek, Litvinov's rank from the legume family. Of the aquatic plants on this list is the water chestnut, or chilim, which grows in a number of floodplain lakes in the Urals, below the cities of Orenburg and Ilek. A large group of rare plants of the region (43 species) are endemics and relics. Ural rock-mountain-steppe endemics are the remains of ancient vegetation developed on stony and gravelly soils in the Tertiary period. This list includes needle-leaved and Ural carnations, Ural larkspur, provincial onosma, holly skullcap and other species.

The relict species of the region are Cossack juniper, desert oatmeal, solar clausia, Siberian istod, as well as floating salvinia and water chestnut, which have been preserved since the pre-glacial period. Many plants of the forests, steppes and meadows of the Orenburg region are medicinal. The most common are henbane, valerian officinalis, spring adonis, St. other.

Floodplain forests, preserved in almost all significant rivers of the region, are formed by silver and black poplar, willow, less often elm. On the floodplains of Samara, the Urals and Sakmara, a significant area is occupied by oak forests.

Separately, it should be said about the gallery and peg plantations of black alder (black alders) growing along streams and mountain rivers, as well as swampy places on the Common Syrt, in the Ilek valley and the Guberlinsky mountains. The ravine-beam pegs and woods of the hilly-ridged watersheds of the steppe zone consist mainly of warty birch and aspen. Oak grows along the watersheds up to the Ural valley. In the east of the region in the upper reaches of the river. The forest-steppe appearance of the landscape is given to the landscape by pine forests with an admixture of larch and birch-aspen pegs.

The sanitary state of forests remains ecologically difficult. The area of ​​active centers of forest pests and diseases in the forestry enterprises of the Orenburg Administration is over 15 thousand hectares.

Given the exceptionally low forest coverage of the territory, most of the region's forests should be considered as nature reserves for various purposes: nature reserves, landscape and botanical reserves, natural parks, and monuments.

Orenburg soil formation steppe chernozem

1.4 Soil formation factors

The Orenburg region is located in the foothills of the southern Urals. The formation of its surface is associated with the development of the Ural folding. In the geological history of this territory, periods of mountain building alternated with periods of relative calm. The continental period was interrupted by the advance of the seas. The northwestern part is characterized by the predominance of horizontally variegated Permian deposits. As you move south, younger deposits appear - Triassic, Jurassic and Neogene.

As we move to the east and approach the Ural folding, the coherence of the bedding is broken. Here, the deposits are dislocated and folded into folds of meridional and near meridional strike. The rocks composing these folds are diverse in age and lithology. The Cis-Urals is composed of alternating bands of Carboniferous and Permian deposits.

Of the soil-forming rocks in the region, there are most loose deposits of heavy mechanical composition (clay and heavy loamy) and less light (light loam, sandy loam and sand). Fine-earth rocks cover the plateau, slopes and terraces of rivers with a rather powerful cloak. In small areas, there are eluvium of dense rocks, which is confined to steep slopes and massifs of small hills.

A special place among the loose sedimentary rocks is occupied by the ancient variegated weathering crust of dense rocks. Due to a number of features of the mineralogical, mechanical and chemical composition, it significantly affects the process of soil formation.

A characteristic property of the ancient variegated weathering crust, as the name itself says, is a variegated color (from white to bright red and purple). Often, for several meters, the whole gamut of colors with bizarre transitions is observed. These deposits are products of kaolin weathering and are devoid of carbonates, sometimes containing secondary accumulations of readily soluble salts. Under the conditions of modern weathering, bedrocks give brown loams, carbonate in the steppe zone, especially in its southern part.

Quaternary eluvium of bedrocks is distributed in the area of ​​outcrops of bedrocks and is distinguished by brown color. The mechanical composition of the eluvium of dense rocks depends on their mineralogical and petrographic composition, and on part and on the dimension of mineral grains. There are all kinds of minerals from sandy loam to clay.

The eluvium always contains little dust and quite a lot of silt. The bedrock eluvium usually contains a significant amount of rubble. There is little of it in the upper part of the profile; below, the rubble increases (up to 85-90 weight percent).

The surface of soils developed on a thin eluvium of dense rocks is often covered with the so-called shell - a layer of crushed stone formed as a result of washing out and blowing out fine earth. The products of the destruction of metamorphic and igneous rocks have the greatest rubble. Deluvial deposits of a fairly constant mechanical composition are formed. Among them are light clays and heavy loams. Deluvial deposits contain a small amount of easily soluble salts. In some chlorides and sulfates are absent.

The ancient alluvial deposits of the above-floodplain terraces of rivers usually have a heavy loamy and clayey mechanical composition. Rarely among them are sands.

A characteristic feature of the soil cover of the region is its heterogeneity. The soil cover of the Cis-Urals was formed under somewhat more humid conditions than the Trans-Urals. The diversity of the relief, the frequent change in space of soil-forming rocks of different mechanical composition and content of carbonates, the different productivity of the natural herbage predetermined the great diversity of soils in terms of carbonate regime, mineralogical composition and humus content in them. In accordance with this, most of the territory of the Orenburg region is occupied by carbonate varieties of all types of chernozems and dark chestnut soils.

In the north and northwest of the region, the soil cover is based on typical and leached chernozems, formed on deluvial yellow-brown clays and loams, underlain by dense sedimentary rocks. To the south of typical chernozems are ordinary chernozems, which are located from west to east across the entire region. In the western part, they extend south to approximately the upper reaches of the Buzuluk and Samara rivers. Further to the east, its southern boundary is the Ural valley. On the Ural-Tobolsk plateau, these soils occupy the spaces between the valleys of the upper reaches of the Suunduk, Karabutak, and Solonchanka. To the south of the strip of ordinary chernozems, southern chernozems extend. In the south and southeast of the region, they are replaced by dark chestnut soils. In Pervomaisky and Sol-Iletsk districts, dark chestnut soils are represented by separate areas. Within the Ural-Tobolsk plateau, they occupy a wide strip.

Among the chernozems of southern and chestnut soils, solonets and solonetz-saline soils are widespread, especially in areas such as Pervomaisky, Sol-Iletsky, Akbulaksky, Kvarkensky, Gaisky, Novoorsky, Adamovsky, Svetlinsky, Dombarovsky. Soddy-meadow, meadow-chernozem, meadow-marsh, solonetz and solonchak soils are common along river floodplains and terraces.

Typical, ordinary, southern chernozems occupy large areas and constitute the main fund of arable soils in the Orenburg region.

Table 1 - The composition of the soil cover of the Orenburg region

SoilsTotal area Including in % thous. ha% of arable land, hayfields, other pastures Gray forest50.90.4 Chernozems, incl. led out by 279.52,366,53,18,821,6typical634.95,177,52,315,84,74.7 general2678,221,673,918,93,7YUCH 2808,222,869,42,530,44,362,92,933.4POLSLY PROICE ,5 Малосформированные633,05,12,62,384,710,4солонцово-солончаковые2413,619,516,13,470,56,9овражно-балочные211,81,73,19,948,138,9луговые и пойменные733,75,915,630,438,715,3Пески99,30,83,913,739,742,7Выходы горных пород34,10,2- --100.0Other1262.610.3---100.0Total in the region12370.2100.0

The soil fund of the Orenburg region shows a wide variety of soil types and subtypes. At the same time, zonal soils - chernozems, which have a significant reserve of fertility and are distinguished by the highest bioproductivity and environmental stability - are completely plowed up.

Anthropogenic degradation on erosion-prone typical and ordinary chernozems has intensified the processes of transformation of the soil cover into heterogeneous water-erosion structures. As a result, there are almost no fat chernozems left; among ordinary chernozems, the areas of medium-thickness have decreased and the areas of thin varieties have significantly increased. The development of low-humus thin and eroded chernozems also led to a decrease in the humus content and the thickness of the humus horizon, and therefore, they began to acquire the characteristic features of less fertile steppe ones.

2. Soil-geographical zoning Orenburg areas

2.1 Soil zoning

The distribution of soils on the territory of the Orenburg region obeys the well-known basic laws of soil geography - latitudinal and vertical soil zonality, and provinciality.

The front page covers, according to V.V. Dokuchaev, Kama-Samara strip. The chernozems of this band have an average thickness of the humus horizon of 58 cm and contain 9.6% of humus in the A horizon (and up to 11.6% in clay soils).

The second lane (Samara - Irgiz). The chernozem of this band has a transitional character from the soils of the first band to the third. The thickness of its humus horizon is on average 55 cm, and the humus content is 8.7%.

The third strip (basin of the Yeruslan and Bolshoi and Malyi Uzen rivers) is the southernmost. The soils of this strip contain 4.6% humus, the thickness of the humus horizon is 33 cm.

The nature of the location of the chernozem belts and the decrease in the humus content of soils to the south is associated with the peculiarities of vegetation and the conditions for the formation and decomposition of organic matter.

The soil map of the Orenburg region clearly shows the latitudinal location of the main types and subtypes of soils and their change from gray forest podzolized soils and rich chernozems of the north through medium-humus and low-humus chernozems to dark chestnut soils of the south.

Soil regions of the Orenburg region.

Forest-steppe region. Subzone of leached and typical rich chernozems:

Aksakovskiy with complex soil cover;

Sarinsky, typical chernozems;

Prikinelsky. Steppe region. Subzone of ordinary chernozems;

Obkhdesyrtsky, ordinary chernozems;

Buzuluk sandy forest;

Kvarkensky, with a complex soil cover;

Samara-Sakmarsky. Subzone of southern chernozems:

Ural-Samarsky, with a complex soil cover;

Priuralsky, southern chernozems;

Priileksky;

Orsky, with a complex soil cover;

Uralo-Tobolsk;

Ural-Ileksky, sandy loamy soils;

Piedmont gravelly chernozems.

Dry steppe area.

Subzone of dark chestnut soils:

Ilek-Khobinsky;

Zauralsky;

Dombarovsky, solonetzic soils;

Dombarovsky, sandy loamy soils.

The area of ​​floodplains of the rivers of the steppe and dry steppe:

Forest and meadow floodplains of the chernozem zone;

Meadow floodplains of the chestnut zone.

In the westernmost part of the region, soil zones are located latitudinally. In the central part, they descend to the south and, skirting the Ural folding in the east, again stretch almost in a latitudinal direction.

The vertical zonality of soils is manifested in the fact that in the central part of the region, due to an increase in absolute elevations, dark chestnut soils are replaced by southern ordinary soils and, finally, by rich chernozems covering the low spurs of the Ural Range.

Thus, the map is compiled on the basis of detailed soil-cartographic materials. Neustruev singled out soil zones: podzolic and chernozem. The latter was divided into subzones of fat, ordinary and poor chernozems. Zones and subzones were divided into two provinces, Cis-Urals and Trans-Urals.

The soil zoning of the Orenburg region did not fundamentally differ from the zoning of Neustroev. In terms of detail, the zoning of Rozhants is close to the zoning of Neustroev. Rozhanets divided the soils of each subzone of chernozems according to their mechanical composition and rubble. In total, he identified 15 districts. The boundaries of the districts were clarified, and in the eastern part they were detailed in comparison with the boundaries given by Neustroev. This clarification was carried out on the basis of new soil-cartographic materials.

As a result, it was possible to distinguish three vegetation zones in the region: forest-steppe, steppe and dry-steppe and four soil subzones: typical fat, ordinary, southern chernozem and dark chestnut soils, and within them - 20 soil regions.

2.2 Soil belts, regions, zones, provinces, districts

The Orenburg region is divided into the East European Plain, the Ural mountain country and the Turgai plain country.

The East European Plain includes:

Forest-steppe zone (Province of the forest-steppe high Trans-Volga region):

a) Bugulma-Belebeevsky high-plain district:

Verkhnesoksko-Belebeevsky high-plain district;

Verkhnedemsko-Salmyshsky syrt region.

b) All-Syrtovsky elevated-ridge district:

Samara-Kinelsky syrt region;

Buzuluksko-Borovsky hilly-sandy forest area.

Steppe zone:

1. Steppe province of the High Trans-Volga region:

1.1. Cis-Ural syrt-plain steppe subprovince:

a) All-Syrtovsky elevated ridge-hilly district:

Buzuluk low-syrt region;

Toksko-Uransky middle-syrt region;

Samara-Salmysh high-syrtovo-watershed area.

b) Sakmara-Priuralsky hilly-ridged district:

Sakmara-Yushatyrsky ridge-hilly region;

Sakmara-Uralsky interfluve elevated-ridged region (Sludnye Gory);

1.2. Ural-Ilek southern steppe subprovince:

a) Ural-Ilek hilly-flat area.

2. North-Caspian southern steppe province:

a) Priuralsko-North-Caspian lowland-plain district:

Shagano-Kindelinsky flat-plain region;

Priileksky sandy-hummocky area.

b) Ileksko-Khobdinsky hilly-flat district:

Khobdinsky hilly-flat area.

The Ural mountain country includes:

South Ural region:

1. South Ural low-mountain forest-steppe province:

a) Nakassko-Iksky low-mountain district:

Nakassky low-mountain remnant-hilly region.

b) Prisakmarsko-South Ural low-mountain forest-steppe district:

Kasmaro-Sakmarsky low-mountain region;

Katralo-Kuragansky low-mountain region.

2. Forest-steppe province of the Trans-Ural Plateau:

a) Upper Sununduk-Karagansky hilly-ridged region.

3. South Ural low-mountain steppe province:

3.1. Sakmara-Guberlinskaya steppe subprovince:

a) Nizhneiksko-Ziyanchurinsky hilly-ridge district:

Nizhneiksky ridge-ridged area;

Giryalo-Kuvandyksky interfluve low-mountain-ridge area;

b) Sarinsky-Guberlinsky low-mountain district:

Low-mountain-plain region of the Sarinsky plateau;

Guberlinsky valley-small hillock region;

Guberlinsko-Priuralsky hilly-ridged area.

c) Tanalyksko-Iriklinsky remnant-hilly district:

Tanalyksko-Urtazymsky remnant-hilly region.

3.2. South Steppe sub-province of the Sub-Ural Plateau:

a) Burtinsko-Aktykyl low-mountain ridge-ridge district:

Burtinsky hilly-ridged area;

Aktykyl-Aytuar low-mountain-ridge area.

4. Steppe province of the Trans-Ural Plateau:

4.1. Ural-Tobolsk steppe subprovince:

a) Uralo-Tobolsk high-plain district:

Iriklinsko-Sunduksky valley-upland area;

Suunduksko-Kumak high-plain region;

Verkhnetobolsko-Kumaksky high-plain region.

4.2. Orsk-Mugodzhar dry steppe subprovince:

a) Orsko-Kumaksky hilly-ridged district:

Nizhneorsky low-plain region;

Kumaksko-Kiimbaysky hilly-ridged area.

The Turgai Plain Country includes:

North Turgai dry steppe province:

a) Zhetykolsko-Aiken endorheic-lake region.

forest-steppe

Subzone of alkaline and typical fertile chernozems. The forest-steppe, which includes leached rich and typical rich chernozems, stretches in a narrow strip from northwest to southeast, along the border of the Orenburg region. The soil cover of the forest-steppe varies within the subzone: not only from north to south, but also from west to east. In the western part, the soil cover is dominated by leached rich chernozems. Typical rich chernozems occupy extremely limited areas and do not form zones. As we move east, due to some increase in dryness and continentality of the climate, leached rich chernozems are replaced by typical rich ones. In the central part of the region and in the Trans-Urals, typical rich chernozems dominate.

The transition from the forest-steppe to the steppe and the change from typical or leached chernozems to ordinary chernozems are not the same throughout the subzone. Soil distribution patterns are also different depending on specific conditions: topography, parent rocks.

Aksakovskiy district with a complex soil cover is located in the forest-steppe, in the subzone of leached fat chernozems.

The area covers the watershed of B. Kinel and Salmysh, stretches in a narrow strip along the right bank of the B. Kinel, along the border of the Orenburg region.

The territory is a high (350-500 m) dissected plateau, the so-called Belebeevsky. The depth of the incision of the rivers is 100-150 m. The plateau is composed of lithologically variegated deposits of the Tatar stage and the Belebey suite of Perm. The surface is strongly dissected, the parts of the plateau itself are extremely small. Most of the surface is dissected slopes. The watersheds are asymmetrical.

The slopes of the northern, northwestern, and northeastern exposures are gently sloping, covered with a rather thick stratum of deluvial heavy loams (and, less often, light loams). Arable lands located on these flattened gentle slopes are covered with leached rich clayey and loamy chernozems.

The slopes of the southern, southeastern and southwestern exposures are mostly steep and dissected by short but deep ravines and ravines with oak and birch pegs. The steppe areas on these squabbles have a sparse vegetation cover. The soils of steep slopes are rich, of varying thickness, usually gravel chernozems and gray forest soils. Spots of residual carbonate chernozems are not uncommon.

Due to the deep incision of the rivers, erosion is developed quite intensively, therefore, when the natural vegetation cover is destroyed, anti-erosion measures must be provided.

The Sarinsky region of typical fat chernozems is located in the Trans-Urals, within the boundaries of the Novo-Pokrovsky administrative region, occupying part of the so-called Sarinsky plateau. This is an ancient leveled surface, where various bedrocks have undergone erosion and leveling - crystalline schists, conglomerates, greenstone rocks, marls and sandy deposits. The absolute heights of the flat plateau range from 400 to 460 m. The plateau is overlain by diluvial heavy silty loams of various thicknesses. Groundwater is very deep. From the south and west, its dissected edge adjoins the Sarinsky plateau: the small hills of the Sakmara and Guberlinsky mountains.

The northern part of the Sarinsky plateau is covered with heavy loamy typical rich medium-thick chernozems, and the southern part is covered with ordinary ones. The soil cover is homogeneous. Soils are highly fertile. Most of the surface has been plowed up, only in some places have preserved areas on which virgin forb-feather grass-shrub steppes are developed.

In the west and south, where the plateau turns into a small hillock, oak-birch pegs grow along the tops of the beams. Here is the eastern border of the modern distribution of oak.

The amount of arable land is 51.0%, hay - 1.9%, pasture - 30.0%, of which 7.2% are mountain pastures. Ravines and gullies occupy 3.7%. Despite the rather large area of ​​pastures and pastures, the expansion of arable land at their expense, especially on riverine massifs, should be approached with caution. It should be borne in mind that plowing can lead to a sharp increase in planar washout and a drop in soil fertility. Therefore, the possibility of expanding arable land here is limited. In terms of arable soil fertility, this is one of the best districts in the region. Due to the great difficulties in oak cultivation and low quality, it is better to exclude it from industrial crops.

The Prikinelsky district is located in the area of ​​change of typical rich chernozems to ordinary ones. It includes six administrative districts - Buguruslansky, Matveevsky, Derzhavinsky, Krasno-Partizansky, Grachevsky and Ivanovsky. It includes the watersheds of the rivers B. Kinel - M. Kinel and M. Kinel - Borovka.

For each of the watersheds and for the interfluve as a whole, a pronounced asymmetry of the slopes and the corresponding regularity in the distribution of parent rocks and soils are characteristic. Thus, on the highest parts of the watersheds, we encounter flat plateau surfaces overlain either by a thin layer of deluvial loams or, more rarely, by bedrock eluvium. The plateau of the watershed to the north gradually turns into a gentle slope covered with loams (usually heavy), and then into wide, then into narrower terrace surfaces.

On the slopes and on the plateau, typical rich chernozems are usually found. On terraces of rivers, soils are sometimes less humus - these are ordinary chernozems. The surface of the plateau, slopes and terraces are plowed up. Only along the shallow ravines that divide the gentle northern slope and terraces, there are areas with forb-feather grass steppe vegetation.

The southern slopes of the watersheds are steep and heavily dissected by a system of gullies. They often expose different bedrocks. At the tops of the beams there are birch or oak lines. Where light bedrocks come to the surface, pine is often found. On the southern slope, chernozems are less humus-rich (usually medium humus).

This is an area of ​​intensive agriculture. The area has highly productive soils, however, the yield on them is low due to non-compliance with agrotechnical rules.

The subzone of ordinary chernozems runs through the central part of the region in a strip up to 60 km wide. In the foothills, it descends somewhat to the south, makes a slight trough, and in the east it rises again to the north, going beyond the region. This violation of the latitudinal location of the subzone is associated with the influence of the Ural folding, near which the subzones acquire a northwestern strike. Soil subzones are compressed between the southern tip of the mountains and the steppes of Kazakhstan. Thus, the width of the subzone of ordinary chernozems here reaches only 15 km. In the east, as one moves away from the mountains, the influence of the latter weakens, and the subzone, rising to the north, expands.

The increase in continentality to the east within the subzone somewhat changes the properties of ordinary chernozems. Humus is unevenly distributed along the profile (linguistic). The amount of bicarbonates in the soil solution increases, sometimes easily soluble salts appear in the lower part of the profile. The southern boundary of the subzone of ordinary chernozems is clearly visible only in the eastern part of the region. In the west, this transition is complex and stretches over a large area due to the large heterogeneity of the mechanical composition of the rocks and the dissection of the relief.

As a first approximation, the boundary between ordinary and southern chernozems (from west to east) can be drawn along the river. Samara, further along the watershed of the rivers Sakmara - Ural and, finally, along the valley of the river. Guberl, where it goes beyond the Orenburg region.

The relief works in two ways. On the one hand, slope exposure has an effect: on northern, wetter and colder slopes, more northern soil subtypes appear; along the southern, drier and warmer slopes, the soils of the more southern subzone move to the north. On the other hand, the distribution of soils is influenced by the absolute height of the terrain: ordinary chernozems are noted on higher surfaces, and chernozems transitional to southern ones are noted on low surfaces. So, on the slope to the river. Spots of southern chernozems are not uncommon in Samara, while the highest flat areas of the Samara interfluve are Buzuluk and the left banks of the river. Buzuluk is occupied by ordinary chernozems.

The influence of the relief is combined with the influence of rocks. The interfluve between the Sakmara and the Urals is a classic example of such a combined influence of exposure and parent rock on soils. Northern slope to the river. Sakmare is covered with heavy deluvial loams with ordinary chernozems, and the southern slopes to the river. The Urals are occupied by southern chernozems on rubbly, relatively lighter products of the destruction of primary Permian rocks. The clearness of the change of soils in this segment, apparently, is explained by the small width of the subzone.

The All-Syrt region of ordinary chernozems occupies the northeastern part of the General Syrt and individual sections of the Permian plateau, located on the watershed of the rivers of the Volga and Ural systems. It includes the following administrative regions: Aleksandrovskiy, Luxembourgskiy, Belozerskiy, Oktyabrskiy, Gavrilovskiy, Ekaterinovskiy, Sakmarskiy and Saraktashskiy.

Flat surfaces and ancient terraces are covered with yellow-brown loams and clays 3 to 12 m thick. They are underlain by ancient alluvial sands or bedrocks. They are dominated by clayey ordinary chernozems, the surface of which is almost completely plowed up. On the terraces, patches of saline medium-humus chernozems are not uncommon. Where the beams dividing the slope open, on the surface of the terrace, meadow solonetz complexes are formed, used for grazing.

Red and pink marls and sandstones are exposed on watersheds and southern slopes. Here, crushed stone leached and residual carbonate chernozems are replaced by eroded soils and bedrock outcrops. It is also grazing land.

Sometimes watersheds are crowned by a narrow plateau composed of usually light Permian rocks. At the tops of gullies and ravines, especially on light deposits, birch and oak coppice groves are not uncommon.

The plowing of the region is high (56-71%). A slight expansion of arable areas is possible, but in some cases it will require reclamation measures.

The Buzuluk sandy forest region is located in the west, on the border with the Kuibyshev region, in the northern part of the Buzuluk administrative region. This is the Buzuluk pine forest, widely known in the literature. It occupies the terraces of the river formed by sandy alluvium. Samara, as well as the slopes of the native coast, composed of sandstones. The sandy alluvium has been blown over, the relief of most of the boron is a well-pronounced dune. The dunes are of different sizes.

Pine forests grow on the dunes. On the outskirts of the massif, where the alluvium of the terrace is replaced by eluvium-deluvium of sandstones on the bedrock bank, coniferous forests give way to broad-leaved ones. This forest area in the steppe is of great industrial and scientific importance.

In the depressions between the dunes, the surface is swampy. Meadow-marsh soils are located here. The surface of the dunes, their tops and slopes are occupied by soddy weakly podzolized sandy and sandy loamy soils. They are characterized by a significant development of the sod process and a weak manifestation of the podzolization process.

The Kvarken black earth region with a complex cover is located in the northeastern part of the region, on the territory of the Kvarken administrative region.

Located in the Trans-Urals, on the eastern slope of the Ural Mountains, the area is composed of acidic, less often metamorphic igneous rocks. The bedrock was abraded by the sea. Traces of this abrasion are still clearly visible on high leveled surfaces (smooth flat outcrops of granite on watersheds).

Now it is a high dissected plateau, where bedrocks are overlain by a very thin sequence of loose Quaternary deposits of eluvium-deluvium. Its thickness is different, which is apparently due to the uneven basement of bedrock. The surface is dissected by a system of riverine dens, at the tops of which buried remains of ancient variegated weathering crusts are found.

The area is dominated by forb-feather grass steppe with birch pegs along hollows and depressions. The plowed area of ​​the soils of this region is quite low (43%). This is due to the heterogeneity of the soil cover and different soil fertility.

The Samara-Sakmarsky district is located in the zone of transition from ordinary to southern chernozems. It covers the following administrative districts of the region: the left-bank part of Buzuluksky, Kurmanaevsky, Totsky, Sorochinsky, Novo-Sergievsky, Andreevsky, the right-bank parts of the Pokrovsky and Perevolotsky districts, as well as the Pavlovsky district.

The region is steppe, with split forests, located in the highest and relatively weakly dissected part of the Common Syrt, therefore, the asymmetry of the interfluves, characteristic of the common Syrt, is weakly expressed here. The relief is ridged. The surface is divided into numerous small watersheds. The area is composed of Permian, Triassic and, partially, Jurassic bedrocks of different lithological composition. Bedrock determines the mechanical composition and degree of soil salinity. Where sandstones of the Triassic, Permian, and Jurassic prevail, the soils are usually light and medium loamy in mechanical composition. Occasionally, at the outcrops of chalk rocks, the soils are heavy loamy.

Jurassic sandstones appear at higher elevations than Triassic and Permian. They are well sorted, do not contain silt and carbonates. The soil cover on them is homogeneous, the mechanical composition is light, and there are no alkaline soils. The relief is leveled.

Permian sandstones, in contrast to the Jurassic ones, are clayey, usually carbonaceous (marly sandstones). The soils on them are heavier in mechanical composition than on the Jurassic sandstones.

Ordinary and southern chernozems are common in the region. Ordinary chernozem occupies the slopes of northern and northeastern exposure. It has a medium loamy, less often clayey mechanical composition. The southern slopes are occupied by southern chernozems, usually lighter in texture, developed on the eluvium of bedrocks. This pattern is manifested in small, latitudinally elongated interfluves of the left tributaries of the Samara. At the same time, there is a relationship between the change of zones and the absolute mark of the terrain (in combination with the exposure). So, on the watershed, more humus soils are formed, on the slopes - less humus.

Soils are generally quite fertile. On the southern chernozems, it is necessary to strengthen measures to combat moisture (Prasolov LI, 1939).

The subzone of southern chernozems occupies a significant part of the territory of the region, covering in the west the watersheds of the rivers Samara - Ural, Ural - Ilek. In the east of the Ural-Tobol interfluve, the boundary of the subzone rises 15 km to the north than in the west. In general, the strike of the subzone is close to the latitudinal one. In the foothills, it is compressed and has a diameter of up to 15-20 km, and in the Trans-Urals its width reaches 70 km. The growth of continentality to the east affects the southern chernozems of heavy mechanical composition, in which the nature of the humus horizon changes. To the east, “linguistic” appears: the areas covered with solonetsous chernozems and solonets increase, which is associated not only with the influence of the characteristics of the parent rocks, but also with an increase in the dryness of the climate.

Significant areas of the subzone are occupied by light low-humus chernozems with reduced effervescence. They are most numerous on the southern slope of the General Syrt, where they form on sedimentary bedrocks of light mechanical composition (Permian, Triassic, Jurassic), exposed along steep slopes to rivers. On the slopes, there is intense planar erosion, which prevails over ravine erosion. Since the dense substrate is not deep, the ravines are shallow and quickly overgrow. Their bottoms are covered with meadow and weed vegetation. When plowing, sometimes there is a revival of beam erosion.

The heterogeneity of parent rocks, as well as the dissection of the surface, determine the diversity of the soil and vegetation cover. At rock outcrops, thin, often gravel, low-humus chernozems give various combinations with steppe solonetzes. Gentle slopes to the rivers and wide flat terraces of the Ural and Ilek rivers are covered with homogeneous arrays of southern chernozems.

With approaching the Ural folding, this regularity in the distribution of soils remains, but the ratio of the areas of chernozems on loose deposits and bedrock changes. The slopes are getting shorter, the terraces narrower. All large areas are occupied by gravelly soils and solonetzes on bedrock, which in this part of the region compose small hills and ridges.

In the eastern part of the region, southern "linguistic" chernozems dominate in all leveled, mostly elevated areas of the relief. The greatest diversity of the soil cover is observed on the slopes to the rivers.

The Ural-Samara region with a complex soil cover is characterized by a heterogeneous soil and vegetation cover with the dominance of southern medium-thick chernozems. It includes the following administrative districts: Teplovsky, Sverdlovsky, Tashlinsky, Mustaevsky, the southern parts of the Pokoovsky and Perevolodsky districts and the northern parts of the Ileksky and Krasnokholmsky districts.

The area is located on the Common Syrt. It occupies the interfluve of the Urals and Samara, as well as the southern slopes to the river. Ural. The watershed is a wavy-ridged massif. The slope is clearly demarcated from the terrace of the Buzuluk River, where ordinary loamy, often cartilaginous chernozems are located. In the flat areas of the terrace, the soils show signs of meadowness. On the watershed, which is a highly dissected plateau, as well as on the slope to the river. The Urals exposes a variety of politological bedrock sedimentary rocks, sands, chalk, clays, as well as sandy-argillaceous strata, both carbonate and non-carbonate.

The soil cover is heterogeneous. The southern low-humus with low effervescence thin gravelly chernozems alternate with solonetsous chernozems and steppe solonetzes. Solonetzes are developed on clays, and solonetsous chernozems are developed on two-membered sediments. The emergence of residual carbonate chernozems is timed to the outcrops of marl and chalk. There are many of them in the western part of the region on the eluvium of chalk-like limestones and carbonate sands. There is no continuous vegetation cover on bedrock outcrops.

In the depressions between the hills and ridges there are reclaimed meadow-chernozem soils under meadow vegetation with thickets of shrubs. In general, the area gives the impression of a forest-steppe, although its soil and vegetation cover is typically steppe.

Arable lands in the region average about 61%. This value varies greatly from region to region. In order to expand the fund of arable areas, measures are needed to combat solonetzic soils. Large areas cannot be used due to rockiness.

The Ural region of southern chernozems stretches in a wide strip along the left bank of the river. Ural from the borders of the West Kazakhstan region in the west to the Aktobe region in the east. It covers the northern part of the Ural-Ilek interfluve. It includes administrative districts: Chkalovsky, Burtinsky, south of Krasnokholmsky.

The area is located on the Poduralsky plateau. In the watershed part of the plateau, bedrock outcrops are common, forming hilly massifs. The slopes are gentle, long and almost imperceptibly pass into the terrace of the river. Ural. River valley The Urals is asymmetric (it expands either the right or the left part of the valley). The left-bank part of the valley to about the mouth of the river. Utva is wide and has all three wide flat loamy terraces. In the Ural wide zone, the bedrocks that make up the watershed are covered by a layer of Akchagyl marine sediments, on which brown loams of the Quaternary age usually lie. The relief is flat, especially in the part adjacent to the river. Ural.

Gentle, almost leveled slopes from the watershed, as well as terraces, are covered with typical feather grass steppe. The ravines dividing the slopes of the watershed and the terrace are not numerous, but deep and overgrown with meadow and weed vegetation. The southern chernozems of heavy mechanical composition dominate. They are distinguished by a small thickness of the humus horizon (the thickness of the A + horizons fluctuates about 40 cm), and in terms of humus content they approach dark chestnut soils. Significant massifs are occupied by dug up chernozems. On the watersheds at rock outcrops (mostly Permian) there are solonetz steppe complexes. The mechanical composition of soils is heavy almost everywhere. Only in places on outcrops of light rocks or on lighter alluvial deposits along terraces is it somewhat sandy (especially in the section between the villages of Krasny Kholm - Ilek).

Currently, woody vegetation in the area is almost absent. There are only a few preserved woods along the cliffs of the coast and in ravines, and in light bedrock. The area is agricultural, but with a significant proportion of animal husbandry. The instability of moisture in the area requires a set of measures to fight for moisture and increase the strength of the soil structure. Irrigation has a great effect

The Priileksky black earth region stretches along the Ilek River. It includes the Sol-Iletsk administrative region and the northern part of Ak-Bulak.

The area covers the terrace of the river. Ilek and the southern part of the Ural-Ilek watershed. The watershed is a series of small hills, composed of Jurassic and Cretaceous sandy-argillaceous, calcareous-marly deposits. In the west, Jurassic and Cretaceous rocks are strongly eroded, and Permian and Triassic clayey carbonate, sandy-clayey, and sandy-conglomerate layers approach directly to the surface.

The soils here are steppe solonetzes and solonetsous low-humus chernozems. There are many residual carbonate chernozems on carbonate rocks. On terraces and gentle slopes, mostly covered with arable land, there are areas of virgin feather-grass steppe.

Southern chernozems dominate here, usually thin, less often medium thick on deluvium or ancient alluvium.

Southern chernozems are the dominant soil of the region. In the depressions between hills and ridges and on the slopes of the northern and western exposures, they are replaced by ordinary chernozems with signs of meadows.

Plowed land in the region is about 38%; under arable land is less than half of the entire area. The main part of the soils is used for pasture land (40%).

The Ural-Tobolsk black earth region is located in the Trans-Urals, on the border with the Kustanai region. It covers part of the Ural-Tobolsk watershed, within the boundaries of the northern part of the Adamovsky district of the region. The area lies within the abrasion-erosion plain of the Trans-Urals.

The slightly undulating surface of the basement of bedrocks is overlain by a thin layer of deluvial heavy loams. However, outcrops of bedrocks are not uncommon along the hilly massifs of the watershed. The undulating surface is only slightly dissected by shallow hollows and gullies. Soft ridges are a characteristic feature of the relief. On tops of hollows and beams birch-aspen woods are located.

Large areas of the territory before the development of virgin lands were a beautiful virgin equal-grass-fescue-feather grass steppe.

The tillage of soils in the region before development was low (15.7%), while the area of ​​pasture massifs was 64.6%, and hayfields - 12.8%. The extremely small area of ​​arable land was explained not by the poor quality of the soil, but by the low population of the region. Soils have conditionally satisfactory forest-growing properties.

dry steppe

The Zauralsky region of dark chestnut soils is located at the southeastern border of the region, within the southern part of the Adamov region. By the similarity of the soil cover, a smaller massif is attached to it, which lies on the left bank of the river. Or, in the western part of the Dombarovsky district. The area is located on the abrasion Zauralskaya plain. The soils are dark chestnut "tongue", heavy loamy, effervescent from the surface. Carbonates and gypsum lie higher than in southern chernozems; gypsum is found at a depth of 80-100 cm.

Along the slopes to the hollows and on the bends of the slopes, variegated barks shine through. Steppe solonetzes are formed on them in combination with solonetsous soils.

On the bottoms of the hollows, the soils are meadow-chestnut. Many of the major depressions in this undulating plain are occupied by lakes. Lakes lying on variegated rocks of ancient weathering (barks) are salty, and on bedrocks they are fresh. In the southeast the plain decreases. A large depression with lakes is formed, filled with saline variegated products of ancient weathering. The lakes are bordered by either a wider or a narrower strip of solonetzes and solonchaks. Between the lakes, along with dark chestnut soils, there are many meadow chestnut soils. There are rock outcrops with rubbly soils and solonetzic complexes.

The dark chestnut soils of the region are the main arable fund, which is still little used. The area can be considered conditionally forest-suitable, with the obligatory strengthening of measures for the accumulation and conservation of moisture.

The Dombarovsky district of solonetzic soils is located on an abrasion plain, on the interfluve of the Ori and Kumak, in the eastern part of the Dombarovsky administrative region. The area is composed of bedrock. In places, ancient weathering crusts - variegated clays - have been preserved on the rocks. From above, bedrocks and their weathering products are overlain by a thin discontinuous cover of modern sandy loam sediments. The surface is hilly. Wide flat hollows between the hills are occupied by meadow-chestnut soils. On the hills, variegated barks come to the surface. Salt licks are formed on them. On leveled areas (flat hills and their slopes), the sandy loam deposits are thicker, and the solonetsity of the soils decreases. Chestnut loamy sandy soils appear here. In some places, igneous acidic rocks with thin gravel soils come to the surface. In general, steppe solonchak solonetzes in combination with strongly and weakly solonetzic dark chestnut soils dominate in the region. Large areas of non-arable soils - solonetzes, solonetsous soils and rock outcrops - determine the direction of agriculture in the region. This is mainly a livestock area.

The Dombarovsky region of sandy loamy soils is located on the interfluve of the Kumak and Ori and covers the central part of the Adamovsky administrative region.

This is a flat surface of a sandy loam terrace, where bedrocks are covered by a thick layer of alluvial sands. Ground waters lie deep (at a depth of more than 10 m).

In places, among the plains, remnant uplands are observed, composed of igneous rocks, mainly granites and granite-gneisses. Soils on the plain are sandy loam, rarely sandy; on the remnant hills - gravel.

The flat surface of the terrace is plowed up by 35%. Significant areas of pasture land (42%). Due to the low natural fertility of soils and the instability of crops over the years, it would be more rational to transfer some of the least productive plots from arable land to grazing lands.

The area of ​​floodplains of the rivers of the steppe and dry steppe. River floodplains consist of low sandy and sandy loam floodplains and high clay floodplains. The duration of flooding of the low floodplain is more than three weeks, the high floodplain is less than three weeks. The structure of the valleys is heterogeneous throughout. Sometimes only one level is traced (usually the lower one). Both the low floodplain and the high floodplain are dissected by channels and oxbow lakes. The width of the floodplains varies from 1 to 10 km.

Area of ​​forest and meadow floodplains of the chernozem zone. In the floodplains of the rivers of the chernozem zone, a number of levels differ. The low floodplain is usually occupied by oshkor or willow forests, which along the ledge to the higher floodplain are replaced by a narrow strip of elm forests and steppe shrubs. The largest part of the high floodplain is occupied by broad-leaved forests. Smaller areas are occupied by shrub meadows, which usually appear on the sites of clearings of floodplain forests.

In the foothills, the structure of the valleys changes. They often have a slit-like character. The rivers are deeply incised and have a large slope, in some places acquiring a mountainous character. Sometimes the valleys are clearly visible here - narrowed areas with an undeveloped floodplain are replaced by areas with a developed, relatively wide floodplain, which has two ledges. Both levels of the floodplain are composed of sandy-pebble deposits. At a low level, along the shallows, shrub willows grow, and occasionally sedge forests.

Treeless areas of river floodplains are used as hayfields, but their area is insignificant. The area has excellent forest conditions.

The area of ​​meadow floodplains of the chestnut zone. In the floodplains of the rivers of this zone, the same two levels are noted as in the floodplains of the chernozem zone. The nature and duration of flooding of the high and low floodplains are also similar.

Due to the increase in the dryness of the climate to the south in the floodplain, the soil cover and the depth of groundwater change, and the degree of mineralization of the latter increases. Soils are alkaline and sometimes saline. They form various complexes of meadow soils, solonetzes and solonchaks. The degree of salinity is determined by the mechanical composition of alluvial deposits, the distribution of which is associated with the topography of the floodplain.

Forest conditions are satisfactory only on a low floodplain, with light washed soils and low-mineralized groundwater. In afforestation of this part of the floodplain, black-salmon and elm should be recommended as the main species. On a high floodplain, selective afforestation is possible in small areas with non-saline soils and groundwater.

3. Soil genesis

3.1Chernozems

3.1.1 Leached chernozems

Leached fat chernozems are formed with a significant amount of precipitation. Therefore, they can be found along the southern border of the forest-steppe, under the meadow steppes. Leached rich chernozems are formed on Quaternary sediments of various mechanical composition - mainly clayey and heavy loamy deluvial sediments.

Leached low-humus chernozems are found to the south, in the subzone of ordinary and, partially, southern chernozems. Here they are formed on parent rocks of relatively light mechanical composition or two-membered sediments with different (compared to clay deposits) water-physical properties. Sometimes the negligible content of calcium in the parent rock of heavy mechanical composition can be the reason for the formation of low-humus chernozems on it, devoid of salts in the upper part of the profile.

In the zone of southern chernozems, on deposits of light mechanical composition - ancient alluvial or eluvium-deluvium of light bedrocks, low-humus chernozems with reduced effervescence develop.

Leached fat chernozems are widespread in the Cis-Urals. They form a subzone located between gray forest soils in the north and typical rich chernozems in the south. The parent rocks are represented by loams and clays, covering the gently sloping slopes of syrts and river terraces with a rather thick cloak. In leached rich chernozems, both processes are most pronounced of the entire subtype - leaching and chernozem (turf). Thus, the leaching process in these soils manifests itself in the removal of easily soluble salts from the soil profile, and of carbonates from the humus horizon. Calcium in the latter appears due to biological accumulation, as well as during periodic rise to the limits of the root layer with soil solutions. Due to fluctuations in the reaction of the medium, acidic decomposition products of organic matter may periodically appear, as a result of which the stability of the absorbing complex is somewhat disturbed.

In leached rich chernozems, features of two opposite processes are observed - intensive biological accumulation and leaching. Various opinions were expressed on the essence of the leaching process. Most authors believe that the process of leaching (decarbonization of the humus horizon) precedes podzolization and is not necessarily associated with the destruction of secondary minerals and the movement of destruction products.

In leached rich chernozems, the phenomena of humus accumulation and their opposite leaching are modern. However, they are of different phases and replace each other in separate (seasonal) periods of soil life. So, in autumn and partly in early spring, organic residues decompose under conditions of good moisture, deep washing and partial anaerobiosis with some formation of acidic decomposition products. In summer, with intensive vegetation, aerobiosis and the dominance of ascending currents, the decomposition of organic residues occurs under conditions when the soil solution is saturated with carbonates. Acidic decomposition products are not formed in this case. Leached rich chernozems are among the most productive soils with high natural fertility. Their structure is good, but prolonged permanent plowing can lead to a loss of structure, or, in any case, to a sharp deterioration in it.

Chernozems are soils formed under perennial herbaceous vegetation of the forest-steppe and steppe under conditions of non-leaching or periodically leaching water regime. The leading process of soil formation is an intensive soddy process, as a result of which a powerful humus-accumulative horizon A develops, nutrients accumulate and the soil is structured.

The herbaceous community consists mainly of grasses and forbs with a strong reticulate fibrous root system.

The annual litter is 20-30 t/ha, while most of it (65-75%) falls on the root mass, which is rich in protein nitrogen, bases (calcium, magnesium). The litter is decomposed mainly by spore-forming bacteria and actinomycetes with sufficient access to oxygen, optimal moisture, without intensive leaching in a neutral environment. Annually, 600-1400 kg/ha of nitrogen and ash elements come with the litter. The ash content of the litter is 7-8%.

In spring, with a sufficient amount of moisture, organic matter quickly decomposes, and plant nutrients are released. In summer, the moisture reserve is reduced to the wilting point. Under such conditions, the mineralization of organic residues is suspended, as a result of which humus is formed and accumulates. Due to the shallow filtration of atmospheric precipitation waters, nutrients accumulate in the upper horizons. Calcium contributes to the fixation of humus. Winter cooling and freezing of soils also contribute to the accumulation of humus, since humus denaturation occurs at low temperatures. In summer, during the period of drying up and in winter, during freezing, humic substances are fixed and become more complex. Humic acids and calcium humates predominate in their composition, leading to the formation of a water-resistant granular structure. This is also facilitated by carbonate soil-forming rocks, high ash content of plant residues, and saturation of ash with bases. The most favorable conditions for chernozem formation are characteristic of the southern part of the forest-steppe. In the steppes, there is a moisture deficit, the amount of incoming litter decreases, therefore, the intensity of humus formation decreases.

Southern chernozems were formed under fescue-feather grass steppe vegetation. They have a small humus layer (from 25-30 to 70-80 cm). Horizon A, 20-30 cm thick, dark gray with a brown tint, lumpy and granular-lumpy structure. Horizon AB (30-40 cm) brownish-dark gray, nutty-cloddy, compacted. Below lies the carbonate horizon B to , brown with streaks of humus, compacted, nutty-prismatic, containing mycelium, efflorescence, farinaceous release of carbonates. VSK - brownish-pale illuvial-carbonate horizon, compacted, prismatic, with a large amount of white-eye. C - fawn carbonate rock, gypsum deposits are found from a depth of 150-200 cm, and easily soluble salts are found from a depth of 200-300 cm. Molehills are observed in the soil profile.

3.1.3 Ordinary chernozems

Ordinary chernozems are common in the northern part of the steppe zone. Formed under forb-fescue-feather grass vegetation. At present, the soils are almost everywhere plowed up. Virgin steppes are preserved only in nature reserves. Soil formation is carried out on loess and loess-like loams, on brown and reddish-brown heavy loams, and partly on the eluvium of bedrock.

In the composition of absorbed bases, calcium significantly predominates over magnesium. The bulk composition of soils is characterized by uniformity, the content of silt is evenly distributed over the soil profile.

Despite the high natural fertility of soils, ordinary chernozems are poor in mobile forms of phosphorus. The soils have an optimal water-air regime, are well structured, and the structure is water-resistant. Soils are widely used in agriculture. The basis for obtaining sustainable yields is the joint application of organic and mineral fertilizers, snow retention, early spring harrowing, furrowing and slotting of fields, and soil erosion control.

Common chernozems are common under steppe forb-fescue-feather grass vegetation. These soils are less powerful than typical chernozems. Their humus horizon ranges from 35-45 cm (cold East Siberian facies) to 80-140 cm (warm facies). Soils have a brownish tint against a general dark gray background and a cloddy structure.

Chernozems are characterized by looseness, high moisture capacity, good water permeability. The structural composition of virgin chernozems is dominated by water-stable granular aggregates, which is especially pronounced in typical, leached, and ordinary chernozems. Podzolized and southern chernozems contain less water stable aggregates. When using chernozems in agriculture, there is a decrease in the content of lumpy-granular, granular, dusty fractions, a decrease in water resistance and a decrease in the size of structural units.

3.2 Dark chestnut soils

The area of ​​dark chestnut soils in the region is small. In the Trans-Urals, they cover the dry steppe Orsk Plain, where they form on yellow-brown deluvial loams.

In the Urals, where the river. The Ural turns to the south, passing from the area of ​​the Syrts to the Caspian lowland, dark chestnut soils appear to replace the chernozems. They cover the area of ​​low syrts of the General Syrt and a significant part of the Sub-Ural Plateau. Typical dark chestnut soils are not solonetzic or very slightly solonetzic.

The dark chestnut soils of the eastern part of the region are somewhat more solonetsous and, like the chernozems, have a “linguistic” humus profile. Recent M.I. Rozhanets were called "gray-chestnut" soils. These soils show a high occurrence of carbonates (37-38 cm) and effervesce in the humus layer (0-22 cm). Gypsum occurs at a depth of 85-131 cm, which allows us to consider these soils as deeply saline. Thus, the salts in the Trans-Urals "linguistic" variants of typical dark-chestnut soils lie higher than in the Cis-Urals. Usually, a shallower depth of occurrence of readily soluble salts and gypsum is accompanied by an increase in solonetzization above salt horizons.

The genesis of the compacted horizon of these soils is unclear. The alkaline reaction excludes the possibility of the formation of this horizon by the type of podzolization with the decomposition of minerals during the acid reaction. The absence of readily soluble salts precludes present-day solonetzization as a result of the incorporation of sodium into the absorbing complex.

Due to the low moisture capacity and lower natural fertility, these soils are best used for forest planting. Only light loams containing a noticeable amount of silty fraction are arable. For the latter, appropriate agricultural technology should be provided. Consideration should be given to the possibility of winding these soils during plowing.

3.3 Gray forest soils

Gray forest soils are formed under mixed forests with a developed herbaceous cover. The soil-forming rocks are eluvium and deluvium of Permian clays of heavy mechanical composition. During the decomposition of organic residues, humus is formed with a high content of humic acids. The process of podzolization is weakly expressed due to the neutralization of acid decomposition products by the ash elements of the litter itself. The accumulation of humus in the soil profile is more intense than in soddy-podzolic soils, but weaker than in chernozems. According to the thickness of the humus horizon and the content of humus, gray forest soils are divided into subtypes of light gray (264 thousand ha, 1.6% of the area of ​​the region), gray (142.9 thousand ha, 0.9% of the area of ​​the region) and dark gray (61.2 thousand ha, 0.4% of the area of ​​the region) soils. Light gray forest soils occupy higher relief elements (upper parts of slopes, tops of ridges), gray forest soils are formed on the middle parts of slopes, dark gray occur on the lower parts of gentle slopes.

Bibliography

1.Afanaseva E.A. On the question of the origin and evolution of chernozem soils. "Soil Science", 1946, No. 6.

.Gerasimov I.P. On the soil-climatic facies of the plains of the USSR and adjacent countries. "Tr. Soil, in-ta”, 1933, vol. 8, no. 5.

.Dokuchaev V.V. Collected works, vol. III. Russian black earth. Ch. V. Zavolzhsky black earth region. Publishing House of the Academy of Sciences of the USSR, M.-L., 1949.

.Neustruev S.S. Natural areas of the Orenburg province. Chkalovsk. publishing house, 1950.

.Prasolov L.I. Soils of the Trans-Volga region (within the eastern part of the Kuibyshev and Saratov regions and the western part of the Orenburg region). In book. Soils of the USSR, vol. III, M.-L., 1939.

.Prasolov L.I., Antipov-Karataev I.N. chestnut soils. In book. Soils of the USSR, vol. I, M.-L., 1939.

.Rozhanets-Kucherovskaya S.E. The vegetation of the region of the Orenburg s.-x. experimental stations (app. 2 maps). "Tr. Orenburg. soil.-botan. Bureau, vol. IV, Orenburg, 1929.