The main types of soils of the Orenburg region. Agriculture of the Orenburg region

Encyclopedia of Plants 22.09.2019

Introduction

1. Soil cover of the Orenburg region

1.1 State land monitoring

2. Sources of soil pollution

2.1 Soil pollution in the Orenburg region

3. Measures for the protection of soils in the Orenburg region

Security environment when handling waste

Conclusion

Bibliography

Introduction

Soil is a special natural formation with a number of properties inherent in animate and inanimate nature, formed as a result of a long-term transformation of the surface layers of the lithosphere under the joint interdependent interaction of the hydrosphere, atmosphere, living and dead organisms.

The soil cover is the most important natural formation. Its role in the life of society is determined by the fact that the soil is a food source that provides 95-97% of food resources for the world's population.

A special property of the soil cover is its fertility, which is understood as the totality of soil properties that ensure the harvest of agricultural crops. The natural fertility of the soil is associated with the supply of nutrients in it and its water, air and thermal regimes. The soil provides the need for plants in water and nitrogen nutrition, being the most important agent of their photosynthetic activity. Soil fertility also depends on the amount of solar energy accumulated in it.

The soil cover belongs to a self-regulating biological system, which is the most important part of the biosphere as a whole. Living organisms, plants and animals inhabiting the Earth fix solar energy in the form of phyto- and zoomass.

The productivity of terrestrial ecosystems depends on the heat and water balances of the earth's surface, which determine the variety of forms of energy and matter exchange within the geographic envelope of the planet.

The land area of the world is 129 million km2, or 86.5% of the land area. About 15 million km2 (10% of land) are occupied by arable land and perennial plantations as part of agricultural land, 37.4 million km2 (25%) are under hayfields and pastures. The total area of arable land is estimated by various researchers in different ways: from 25 to 32 million km2.

The planet's land resources allow food to be provided to more people than is currently available. However, due to population growth, especially in developing countries, soil degradation, pollution, erosion, etc.; as well as due to land acquisition for the development of cities, towns and industrial enterprises, the amount of arable land per capita is sharply reduced.

Human impact on soil is an integral part of the overall impact human society on the earth's crust and its upper layer, on nature as a whole, especially increased in the age of the scientific and technological revolution. At the same time, not only is the interaction of man with the earth intensified, but the main features of the interaction are also changing. The problem of "soil - man" is complicated by urbanization, all great use lands, their resources for industrial and housing construction, growing demand for food. At the will of man, the nature of the soil changes, the factors of soil formation change - relief, microclimate, new rivers appear, etc. Under the influence of industrial and agricultural pollution, soil properties and soil-forming processes, potential fertility change, the technological and nutritional value of agricultural products decreases, etc.

Pollution natural environment- a complex process associated with human activity. The author of the fundamental summary on ecology, Yu. Odum (1975), points out that “pollution is Natural resources out of place", because they are alien to natural ecosystems and, accumulating in them, disrupt the processes of matter and energy circulation, reduce their productivity, and affect people's health.

1.Soil cover of the Orenburg region

soil earth monitoring pollution

The boundaries of the soil zones are irregular and stretched, penetrating one another over long distances. 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 those of 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 approximately to the upper reaches of the Buzuluk and Samara rivers. Further to the east, their 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.

1 State monitoring of lands, analysis of the qualitative state of lands

In the Orenburg region, in order to create a system of the state real estate cadastre, in the development of the federal target program "Creation of an automated system for maintaining the state land cadastre and state registration of real estate objects (2002-2007)", the subprogram "Creation of a real estate cadastre system" (2006-2011) .) the regional target program "Creation of a system of real estate cadastre and management of the land and property complex in the Orenburg region (2005-2011)" was adopted and is being implemented.

The tasks of state land monitoring are:

) timely detection of changes in the state of land, assessment of these changes, forecast and development of recommendations for the prevention and elimination of the consequences of negative processes;

) information support of state land control over the use and protection of land, other functions of state and municipal government land resources, as well as land management;

) providing citizens with information about the state of the environment in terms of the state of the land.

Depending on the objectives of monitoring and the observed territory, state monitoring of lands can be federal, regional and local. State monitoring of lands is carried out in accordance with federal, regional and local programs.

Land monitoring is a long-term system for tracking, controlling and forecasting the land fund. At the same time, the soil is the main, connecting link of all monitoring blocks, it determines the highest degree of information content of the state of the ecosystem.

The relevance of land monitoring work is determined by the deterioration of the ecological state of all objects of the natural environment, and land in particular. In this regard, to achieve ecological balance, a fundamentally new approach to rational land use and nature management in general is required. The adoption of decisions related to the implementation of actions on the ground must necessarily be preceded by an analysis of diverse, reliable and regularly updated data on its state. All this determines the need to organize systematic comprehensive observations of the state of the environment - monitoring and its main object - the earth. One of the best land monitoring services in Russia has been created and is successfully operating in the Orenburg region. It is based on a network of monitoring sites, consisting of reference areas, polygons and soil-erosion catenas.

Based on the main goals of land monitoring, expressed in providing the land use management system and environmental safety with timely information on the state of the land fund, a land monitoring system is being built in the Orenburg region, which consists of:

a) from the placement of benchmark sites on the territory of the region for observation and selection of the most informative and estimated environmental indicators, parameterization;

b) analytical systematization of retrospective materials obtained during monitoring studies for the ecological zoning of the soil cover at the landscape-typological level;

c) compiling target slices of maps;

d) drawing up on paper and electronic basis maps on pollution by heavy metals and pesticides; humus content; soil granulometric composition; spreading the influence of technogenic and exogenous processes that violate state of nature soils and lands, and others.

Monitoring of the lands of the Orenburg region has been carried out since 1993. The work is carried out in accordance with the regional target programs and the "Methodology for improving the further implementation of environmental monitoring of land in the Orenburg region."

A contract for the amount of 830 thousand rubles was signed for the monitoring of the lands of the Orenburg region. with LLC NPP GIPROZEM.

According to the terms of reference, work was carried out on:

monitoring of lands of settlements and territories adjacent to them (Buzuluk, Orenburg, Orsk, Kuvandyk and Mednogorsk);

production of works on taking snow samples and soil samples for contamination with heavy metals during the survey of lands of man-made landscapes of roads;

compiling and maintaining a regional integrated working duty map of the ecological state of lands;

organization and maintenance of GIS monitoring of land areas in the region (creation of a data bank for land monitoring);

analysis of research materials on land monitoring in the Orenburg region for 2009.

During the work on the monitoring program, the main provisions for the development of regional monitoring of lands in the Orenburg region have been developed, which defines the types of analysis and the frequency of their implementation for each category of lands, as well as the concept of compiling a map of the ecological state of lands in the Orenburg region, work on which is underway and involves the use geoinformation (GIS) technologies. The creation of a basic monitoring system is close to completion.

The analysis of research materials on land monitoring in the Orenburg region was carried out and a summary report was prepared. Changes and additions were made to the created electronic version of the integrated working duty map of the ecological state of the lands of the Orenburg region.

At present, the regional land monitoring network of the Orenburg region covers lands of all categories and consists of 66 polygons, 491 reference sites, 21 catenas.

2. Sources of soil pollution

Sources of pollution are:

) Residential buildings and household businesses. The pollutants are dominated by household waste, food waste, faeces, construction waste, heating system waste, worn-out household items; trash public institutions- hospitals, canteens, hotels, shops, etc. Together with faeces, pathogenic bacteria, helminth eggs and other harmful organisms often enter the soil, which enter the human body through food. Fecal residues may contain such representatives of pathogenic microflora as causative agents of typhus, dysentery, tuberculosis, poliomyelitis, etc. The speed of death in the soil of different microorganisms is not the same. Some pathogenic bacteria can persist for a long time and even multiply in the soil and soil. These include pathogens of tetanus (up to 12 years old), gas gangrene, anthrax, botulism and some other microbes. The soil is one of the important factors in the transmission of helminth eggs, thereby determining the possibility of the spread of a number of helminth infections. Some helminths - geohelminths (roundworms, whipworms, hookworms, sidegilides, trichostrongylids, etc.) go through one of the stages of their development in the soil and can remain viable in it for a long time. So, for example, roundworm eggs can remain viable in the soil in the conditions of central Russia - up to 7-8 years, Central Asia - up to 15 years; whipworm eggs - from 1 to 3 years.

) Industrial enterprises. In solid and liquid industrial waste, certain substances are constantly present that can have a toxic effect on living organisms and their communities. For example, non-ferrous and heavy metal salts are usually present in the waste from the metallurgical industry. The engineering industry releases cyanides, arsenic and beryllium compounds into the environment. In the production of plastics and artificial curls, benzene and phenol wastes are generated. Waste pulp and paper industry, as a rule, are phenols, methanol, turpentine, VAT residues.

) Thermal power engineering. In addition to the formation of a mass of slag during the combustion of coal, thermal power engineering is associated with the release of soot, unburned particles, and sulfur oxides into the atmosphere, which eventually end up in the soil.

) Agriculture. Fertilizers, pesticides used in agriculture and forestry to protect plants from pests, diseases and weeds. Soil pollution and disruption of the normal circulation of substances occurs as a result of the underdosed use of mineral fertilizers and pesticides. Pesticides, on the one hand, save crops, protect gardens, fields, forests from pests and diseases, destroy weeds, free people from blood-sucking insects and carriers of dangerous diseases (malaria, tick-borne encephalitis, etc.), on the other hand, they destroy natural ecosystems , are the cause of the death of many beneficial organisms, adversely affect human health. Pesticides have a number of properties that enhance their bad influence on the environment. The application technology determines a direct hit on environmental objects, where they are transmitted through food chains, circulate for a long time through external environment, get from soil to water, from water to plankton, then to fish and humans, or from air and soil to plants, herbivores and humans.

Together with manure, pathogenic bacteria, helminth eggs and other harmful organisms often enter the soil, which enter the human body through food.

) Transport. During the operation of internal combustion engines, nitrogen oxides, lead, hydrocarbons and other substances are intensively released, deposited on the soil surface or absorbed by plants. Each car emits an average of 1 kg of lead in the form of an aerosol per year. Lead is emitted in car exhaust gases, deposited on plants, and penetrates into the soil, where it can remain for quite a long time, since it is poorly soluble. There is a pronounced tendency towards an increase in the amount of lead in plant tissues. This phenomenon can be compared with the ever-increasing consumption of fuel containing tetra-ethyl lead. People who live in a city near highways with heavy traffic are at risk of accumulating lead in their bodies in just a few years, which is much higher than the permissible limits. Lead is included in various cellular enzymes, and as a result, these enzymes can no longer perform their intended functions in the body. At the beginning of poisoning, increased activity and insomnia are noted, later fatigue, depression. Later symptoms of poisoning are disorders of the nervous system and brain damage. Motor transport in Moscow emits annually 130 kg of pollutants per person.

The soil is polluted with oil products when refueling cars in the fields and in forests, at logging sites, etc.

Soil self-purification is usually a slow process. Toxic Substances accumulate, which contributes to the gradual change chemical composition soils, violation of the unity of the geochemical environment and living organisms. From the soil, toxic substances can enter the organisms of animals and people and cause severe illness and death.

Soils accumulate metal compounds, such as iron, mercury, lead, copper, etc. Mercury enters the soil with pesticides and industrial waste. The total uncontrolled releases of mercury are up to 25 kg per year. The scale of the chemical transformation of the surface of the lithosphere can be judged from the following data: over a century (1870-1970), more than 20 billion tons of slag and 3 billion tons of ash settled on the earth's surface. Emissions of zinc, antimony each amounted to 600 thousand tons, arsenic - 1.5 million tons, cobalt - over 0.9 million tons, nickel - more than 1 million tons.

Pollution of the underlying soil surface of the Orenburg region occurs in three directions: atmospheric precipitation, spillage of liquid and accumulation of solid pollutants.

Road transport is the main source of soil pollution with heavy metals and hydrocarbons. Pollutants (heavy metals - lead, manganese, zinc; hydrocarbons, benzo (a) pyrene, etc.) enter the soil indirectly, through air pollution.

Direct contamination of soils as a result of oil spills occurs along highways from vehicles and in areas where the facilities of OOO Buguruslanneft are located (oil wells, pumping stations, pipelines).

The main causes of soil microbial contamination in residential areas are an increase in the amount of solid waste, imperfection of the system for cleaning populated areas, lack of a centralized sewerage system or poor condition. sewer networks, the occurrence of unauthorized dumps.

1 Soil pollution in the Orenburg region

Despite the rather low values of excess MPC, in the soils of the city there are excesses of the content of chemical elements over the values of the natural background: zinc - 4.36-124.31 times, copper - 2.71-72.0 times, lead - 4. 25-13.59 times, cobalt - 3.00-10.60 times, cadmium - 2.75-7.63 times, manganese - 2.54-7.62 times. The calculation of the correlation coefficients showed rather close interactions of zinc, copper, cadmium, lead and nickel with each other. All this indicates the emergence of potential sources of pollution in the area of benchmark sites 3, 11, 13. This conclusion is confirmed by the analytical data of monitoring conducted over 15 years. In these points, the most unfavorable situation is observed in terms of the content of zinc, lead, cadmium.

The ecological and geochemical state of the soil cover of the city of Orsk is formed under the influence of a large number pollution sources. Intensive soil contamination with HMs is observed not only in the territory of sanitary protection zones of industrial enterprises, but also in residential areas.

In 2010 the main chemical element, the concentration of which exceeds the MPC in the soil, is nickel (2.92-60.94 times). At one point (6) exceeds cadmium (2.40 times).

High values of nickel and cadmium affected the values of the coefficient of total soil contamination with HMs. The interval of values in the 2nd and 6th reference areas is 24.44 and 63.65, which corresponds to a moderately dangerous and dangerous degree of pollution.

Availability chemical pollution confirm the excess of the content of chemical elements over the background values: nickel - 3.10-243.77 times, cobalt - 3.70-102.50 times, zinc - 5.96-49.33 times, copper - 3.59- 29.76 times, lead - 3.97-9.28 times, cadmium - 3.38-9.00 times, manganese - 3.72-7.16 times. Calculation of correlation coefficients showed that nickel has close correlations with copper, cadmium and cobalt.

The ecological and geochemical state of the soil cover in Kuvandyk is generally good. Soil pollution is focal and unstable. In 2010, the main chemical element, the concentration of which exceeded the MPC is cadmium (8 benchmark - 2.33 times). At the same time, there are excesses of MPC for zinc (by 2.68-56.83 times), cobalt (by 3.20-13.90 times), cadmium (by 2.63-8.75 times), lead (by 3 .2-6.08 times), manganese (3.09-5.54 times), copper (2.65-3.94 times).

Exceeding the MPC content of the soil cover in Buzuluk in 2010 is observed only for lead (benchmark 3 - 2.32 times and benchmark 9 - 2.17 times) (Table 4.6.2). Soil pollution with HMs is observed not only on the territory of industrial enterprises, but also in the central part of the city.

Basically, the maximum permissible standards exceed zinc, lead, cadmium and copper.

In 2011, the Novokuibyshev Laboratory for Monitoring Environmental Pollution of the Samara TsGMS-R FGBU, in accordance with the State Assignment of Roshydromet, carried out work to determine the residual amounts (RC) of pesticides in the soil of the Orenburg region. The soils of one farm were surveyed: JSC "Druzhba" of the Kuvandyk district (408 hectares of agricultural land under grain crops)

In spring and autumn specialists of MS Kuvandyk selected 10 soil samples in the area of OAO Druzhba. Residual quantities (RC) of 15 pesticides were determined in soil samples: insectoacaricides - DDT and its metabolite DDE; alpha, beta, gamma HCCH; HCB; isomers of polychlorinated biphenyls (PCBs); metaphos; herbicides - atrazine; 2,4-D; dalapon, promethrin, simazine, treflan, THAN.

3. Measures for soil protection

A complex of measures is needed to improve soils. The main preventive measures on soils contaminated with heavy metals are:

improving the agrophysical properties of soils by increasing the doses of organic and phosphate fertilizers;

cultivation of crops characterized by a reduced accumulation of heavy metals (melons, potatoes, tomatoes, etc.);

cultivation of industrial crops;

replacement of the soil layer in especially polluted areas of settlements, soil treatment with humates, which bind heavy metals and convert them into compounds inaccessible to plants;

stimulation of soil-forming processes with the help of special complexes of microorganisms - humus formers, etc.

to reduce dust content, it is necessary to increase the number and density of green spaces.

In addition, explanatory (educational) work is needed among the population, especially among the owners of collective farms.

To ensure the protection and rational use of the soil, it is necessary to provide for a set of measures for its reclamation. Reclamation is subject to lands disturbed and (or) contaminated by:

development of mineral deposits;

laying pipelines for various purposes;

storage and burial of industrial, household biological and other wastes, pesticides.

So, it is necessary to reclaim the landfill ( N-E direction), and the cattle burial ground located on its territory must be mothballed. The Western landfill is subject to reclamation after the construction and commissioning of a new solid waste landfill, which must meet modern standards and regulations in accordance with SP 2.1.7.1038-01.

On the territory of the Asekeyevsky village council in the south-eastern part of the cadastral quarter 56:05:03:05 001, a site was selected for the construction of a new cattle burial ground - at a distance of 1000m from the village of Asekeyevo, at a distance of 500m from the Kisla River. According to the sanitary and epidemiological conclusion, the object belongs to the I hazard class and in accordance with SanPiN 2.2.1./.2.1.1.1200-03, the sanitary protection zone for this cattle burial ground will be 1000m.

To date, it is known that the wastewater from the Asekeevskaya Central District Hospital and several residential buildings is discharged onto the terrain without treatment, therefore, this area, after the construction and commissioning of the treatment plant system, is also subject to reclamation. According to Article 67 of the Water Code of the Russian Federation in areas prone to flooding, the placement of new settlements, cemeteries, cattle burial grounds and the construction of capital buildings, structures, structures without special protective measures to prevent the negative impact of water is prohibited.

3.1 Environmental protection in waste management

The main directions in solving the problems of waste management in the municipality "Asekeyevsky Village Council" are:

maximum use of selective collection of solid waste in order to obtain secondary resources and reduce the amount of waste to be disposed of;

recultivation of existing places of storage and disposal of solid household and biological waste;

construction of a new solid waste landfill and a new cattle burial ground equipped with biological chambers in accordance with sanitary and epidemiological standards and requirements;

optimal operation of the existing and newly commissioned solid waste landfills, taking into account the subsequent reclamation of the territories.

In the draft territorial planning scheme for the region, on the territory of the region, it is proposed to build a waste collection point for the collection and further transportation of waste to the projected waste processing plant. During the implementation of this project, it is possible to re-equip the site of the projected centralized solid waste landfill into a waste collection point.

In accordance with Article 11 of the federal law "On Production and Consumption Waste", individual entrepreneurs and legal entities, when operating enterprises, buildings, structures, structures and other facilities related to waste management, are obliged to:

Comply with environmental requirements established by law Russian Federation in the field of environmental protection;

Develop draft standards for waste generation and limits for waste disposal in order to reduce the amount of their generation;

Implement low-waste technologies based on scientific and technological achievements;

Conduct an inventory of waste and their disposal facilities;

Monitor the state of the environment in the territories of waste disposal facilities;

Provide in in due course necessary information in the field of waste management;

Comply with the requirements to prevent accidents related to waste handling and take urgent measures to eliminate them.

The implementation of the presented set of measures of a planning and organizational nature will restore the ecological balance and improve the sanitary and environmental parameters of the environment on the territory of the municipality Asekeyevsky village council.

Conclusion

The formation of the soil cover in the Orenburg region was significantly affected by the dry, hot climate and the lack of precipitation. The diversity of relief, soil-forming rocks, climate, and vegetation determines the diversity of the soil cover.

State monitoring of lands is a system of observations of the state of lands. The objects of state monitoring of lands are all lands in the Russian Federation.

Depending on the objectives of monitoring and the observed territory, state monitoring of lands can be federal, regional and local.

Based on the results of studies, work performed on monitoring the lands of the Orenburg region on agricultural lands and lands of settlements and adjacent territories, an analysis was carried out and recommendations were developed to eliminate the negative consequences of land use.

Bibliography

1.State report "On the state and protection of the environment of the Orenburg region in 2010"

2.Porshneva E. B., Florova N. B., Radioactive contamination and its assessment, - M., 1993.

.Dobrovolsky G.V., Nikitin E.D., - Preservation of soils as an indispensable component of the biosphere, - M: Nauka, MAIK "Nauka / Interperiodika", 2000.

4.G.V. Dobrovolsky "Soil. City. Ecology”, Moscow, 1997

soil earth monitoring pollution

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

State monitoring of lands, analysis of the qualitative state of lands

State monitoring of lands is a system of observations of the state of lands. The objects of state monitoring of lands are all lands in the Russian Federation.

The tasks of state land monitoring are:

1) timely detection of changes in the state of lands, assessment of these changes, forecast and development of recommendations for the prevention and elimination of the consequences of negative processes;

2) information support of state land control over the use and protection of land, other functions of state and municipal management of land resources, as well as land management;

3) providing citizens with information about the state of the environment in terms of the state of land.

a) from the placement of benchmark sites on the territory of the region for observation and selection of the most informative and estimated environmental indicators, parameterization;

b) analytical systematization of retrospective materials obtained during monitoring studies for the ecological zoning of the soil cover at the landscape-typological level;

c) compiling target slices of maps;

d) compilation on paper and electronic basis of maps on pollution by heavy metals and pesticides; humus content; soil granulometric composition; the spread of the influence of technogenic and exogenous processes that violate the natural state of soils and lands, and others.

A contract for the amount of 830 thousand rubles was signed for the monitoring of the lands of the Orenburg region. with LLC NPP GIPROZEM.

According to the terms of reference, work was carried out on:

Monitoring of the lands of settlements and territories adjacent to them (the cities of Buzuluk, Orenburg, Orsk, Kuvandyk and Mednogorsk);

Production of work on taking snow samples and soil samples for contamination with heavy metals during the survey of lands of man-made landscapes of roads;

Compilation and maintenance of the regional integrated working duty map of the ecological state of lands;

Organization and maintenance of GIS monitoring of land areas in the region (creation of a data bank for land monitoring);

Analysis of research materials on land monitoring in the Orenburg region for 2009.

At present, the regional land monitoring network of the Orenburg region covers lands of all categories and consists of 66 polygons, 491 reference sites, 21 catenas.

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 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 soil and the natural factors that form it, showed the patterns of soil distribution and developed a method for 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 largest area 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 conditions

1.1 Climate

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. Climatic conditions The surveyed territory is 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 as maximum temperature plus 440 FROM

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, exceeding 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 blowing 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 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 Bolshoy 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 section 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

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 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. Feather-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. From aquatic plants in this list - a water chestnut, or chilim, growing in a number of floodplain lakes in the Urals, below the city of Orenburg and Ilek. big group 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 plantings 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

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.

Dense rocks differ in genesis, age, chemical and mineralogical composition. Among the igneous, granites and serpentines are most common. Metamorphic rocks are represented by shales and limestones. The group of sedimentary rocks is the most extensive. It is dominated by clayey and sandy-clayey carbonate Permian deposits, sometimes conglomerates, marls and dolomites. Jurassic deposits are represented by clays, sands and sandstones.

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 rubble 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.

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

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 were almost no rich chernozems left; among ordinary chernozems, the areas of medium-thick chernozems decreased and the areas of thin varieties increased significantly. 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, in connection with which, they began to acquire characteristics less fertile steppe.

2. Soil-geographical zoning Orenburg region

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 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.

The vertical zoning 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. The 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:

Salmysh-Yushatyrsky syrt region;

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 - crystalline schists, conglomerates, greenstone rocks, marl and sandy deposits - have undergone erosion and leveling. 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 bedrock comes 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 trend. The 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 influence of the chemical and mechanical composition of parent rocks is reflected in the appearance of low-humus leached chernozems on light rocks and residual carbonate chernozems on carbonate rocks. Solonetz phenomena in the soils of this subzone are weakly expressed.

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: on higher surfaces, ordinary chernozems are noted, and on low surfaces, chernozems transitional to southern ones. 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 of the Sakmara and the Urals is classic example such a combined effect on soil exposure and parent rock. 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 Common Syrt region of ordinary chernozems occupies the northeastern part of the Common 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 the 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 massifs 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 wide Ural 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 gives big 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 southern part watershed of the rivers Ural - Ilek. 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 plots the territory before the development of virgin lands was 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.

On 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 on small areas with non-saline soils and groundwater.

3. Soil genesis

3.1 Chernozems

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 common 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. Thus, 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.

3.1.2 Southern chernozems

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 solonetzic 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.

Content

UDC 631 (4) (075.14) Soil geography with the basics of soil science

In the course paper Kucheva A.A. Course work: Soils of the Perm region - Perm: 2012 FGBOU VPO Perm State Agricultural Academy, 2012. - 72 p.
The work considers the soil-geographical zoning of the Orenburg region. The natural conditions of the soils of the Orenburg region are described, among which the relief, soil composition, vegetation and soil formation factors are considered. Based on studies of soils in the Orenburg region, consideration of soil zoning, soil-forming processes and soil zones, the place of soils in the Orenburg region in soil-geographic zoning was determined. The genesis of soils in the Orenburg region is described, special attention was paid to dark chestnut soils, ordinary, typical, southern and leached chernozems. The classification of soils of the USSR in 1977 is also considered. In conclusion, an assessment and recommendations are given for the use of soils in the Orenburg region. A list of used literature is attached.
Bible - 7, tab. – 5, fig. - ten.

Introduction

Soil geography is a section of soil science that studies the patterns of distribution of soils on the Earth's surface for the purpose of soil-geographic 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 the comparative geographic method, with the help of which the geographic distribution of soils is studied in connection with soil formation factors. 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 soil and the natural factors that form it, showed the patterns of soil distribution and developed a method for 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. Forests of the region, including a 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.
In the structure of arable land in the region, chernozems occupy 79%, the subtype of dark chestnut soils - 16%, gray forest soils - 4% of the area. Among 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 (Gerasimov IP, 1933).

1. Natural conditions

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 0 C, and of the hottest month of July +22.1 0 C. Winter lasts 4.5 months. The minimum winter temperature reaches minus 40-44 0 C. Summer has approximately the same duration with a maximum temperature of plus 44 0 C (Fig. 1) (Gerasimov IP, 1933).
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, exceeding 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 blowing in winter during snowstorms and in summer during periods characterized by low relative humidity and high average daily temperatures.

Figure 1. Climatic maps of the Orenburg region (Gerasimov I.P., 1933)

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 occurs during the warm period, which somewhat smooths out the aridity of the climate (Fig. 2).

Figure 2. Climatic map of the Orenburg region (precipitation) (Gerasimov I.P., 1933)

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 were observed once every 3-4 years, and in the southern regions once every two to three years (Gerasimov I.P., 1933).
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 pressure 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, during the year there are 73 days without sun (Gerasimov I.P., 1933).

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 Bolshoy 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 section 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 small hilly steppe. 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, softly 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 character of the surface of the Orenburg region makes it convenient for the development of agricultural production (Prasolov L.I., 1939).

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 forbs and steppe grasses (Rozhanets-Kucherovskaya S.E., 1929).
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. Feather-wormwood steppes are characterized by sparseness and spotting of the herbage. Because of the spotting among the Yaik Cossacks, the southern steppe was called the “chubaraya steppe” (Fig. 3) (Rozhanets-Kucherovskaya S.E., 1929).
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.

Figure 3. Vegetation map of the Orenburg region (Rozhanets-Kucherovskaya S.E., 1929)

8 species of orchids growing on the territory of the region are listed in the Red Book, among them are the large-flowered slipper, Lezel's liparis and helmeted 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 plantings 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.
Taking into account the extremely low forest cover of the territory, most of the forest areas of the region should be considered as nature reserves for various purposes: nature reserves, landscape and botanical reserves, natural parks, natural monuments (Rozhanets-Kucherovskaya S.E., 1929).

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.
Dense rocks differ in genesis, age, chemical and mineralogical composition. Among the igneous, granites and serpentines are most common. Metamorphic rocks are represented by shales and limestones. The group of sedimentary rocks is the most extensive. It is dominated by clayey and sandy-clayey carbonate Permian deposits, sometimes conglomerates, marls and dolomites. Jurassic deposits are represented by clays, sands and sandstones.
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 (Neustruev S.S., 1950).
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 also on the size 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 rubble 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. Sands are less common among them (Neustruev S.S., 1950).
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 (Prasolov L.I., 1939)

Soils	total area		Including in %
Soils	thousand ha	%	arable land	hayfields	pastures	others
gray forest	50,9	0,4
Chernozems, incl.
leached	279,5	2,3	66,5	3,1	8,8	21,6
typical	634,9	5,1	77,5	2,3	15,8	4,7
ordinary	2678,2	21,6	73,5	3,9	18,9	3,7
southern	2808,2	22,8	69,4	3,4	23,5	3,7
dark chestnut	530,4	4,3	62,4	6,9	27,3	3,4
for all soil subzones:	6982,1	56,5
underformed	633,0	5,1	2,6	2,3	84,7	10,4
solonetz-saline	2413,6	19,5	16,1	3,4	70,5	6,9
ravine-beam	211,8	1,7	3,1	9,9	48,1	38,9
meadow and floodplain	733,7	5,9	15,6	30,4	38,7	15,3
Sands	99,3	0,8	3,9	13,7	39,7	42,7
Rock outcrops	34,1	0,2	-	-	-	100,0
Other	1262,6	10,3	-	-	-	100,0
Total for the region	12370,2	100,0

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 were almost no rich chernozems left; among ordinary chernozems, the areas of medium-thick chernozems decreased and the areas of thin varieties increased significantly. 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 chernozems (Prasolov L.I., 1939).

2. Soil-geographical zoning of the Orenburg region

2.1. Soil zoning

The distribution of soils on the territory of the Orenburg region obeys the known basic laws of soil geography - latitudinal and vertical soil zonality and provinciality (Fig. 4).

Figure 4. Soil map of the Orenburg region (Dokuchaev V.V., 1949)

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 band 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 (Fig. 5) (Gerasimov I.P., 1933 ).

Figure 5. Soil regions of the Orenburg region (Gerasimov I.P., 1933)
Forest-steppe region. Subzone of leached and typical rich chernozems:
1 – Aksakovskiy with complex soil cover;
2 - Sarinsky, typical chernozems;
3 - Prikinelsky. Steppe region. Subzone of ordinary chernozems;
4 - Obkhdesyrtsky, ordinary chernozems;
5 - Buzuluk sandy forest;
6 - Kvarkensky, with a complex soil cover;
7 - Samaro-Sakmarsky. Subzone of southern chernozems:
8 - Ural-Samarsky, with a complex soil cover;
9 - Priuralsky, southern chernozems;
10 - Priileksky;
11 - Orsky, with a complex soil cover;
12 - Ural-Tobolsk;
13 - Ural-Ileksky, sandy loamy soils;
14 - foothill gravelly chernozems.
Dry steppe area.
Subzone of dark chestnut soils:
15 - Ilek-Khobinsky;
16 - Zauralsky;
17 - Dombarovsky, solonetzic soils;
18 - Dombarovsky, sandy loamy soils.
The area of floodplains of the rivers of the steppe and dry steppe:
19 - forest and meadow floodplains of the chernozem zone;
20 - 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 zoning 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. The 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 turned out to be 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 (see Fig. 5) ( Neustruev S.S., 1950).

2.2. Soil belts, regions, zones, provinces, districts

The Orenburg region is divided into the East European Plain, the Ural Mountainous Country and the Turgai Plain Country (Fig. 6).
The East European Plain includes:
1. Forest-steppe zone (Province of the forest-steppe high Trans-Volga region):
a) Bugulma-Belebeevsky high-plain district:

b) All-Syrtovsky elevated-ridge district:

2. Steppe zone:
2.1. Steppe province of the High Trans-Volga region:
2.1.1. Cis-Ural syrt-plain steppe subprovince:
a) All-Syrtovsky elevated ridge-hilly district:

b) Sakmara-Priuralsky hilly-ridged district:

2.1.2. Ural-Ilek southern steppe subprovince:
a) Ural-Ilek hilly-flat area.
2.2. North-Caspian southern steppe province:
a) Priuralsko-North-Caspian lowland-plain district:

b) Ileksko-Khobdinsky hilly-flat district:

The Ural mountain country includes:
1. South Ural region:
1.1. South Ural low-mountain forest-steppe province:
a) Nakassko-Iksky low-mountain district:

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

1.2. Forest-steppe province of the Trans-Ural Plateau:
a) Upper Sununduk-Karagansky hilly-ridged region.
1.3. South Ural low-mountain steppe province:
1.3.1. Sakmara-Guberlinskaya steppe subprovince:
a) Nizhneiksko-Ziyanchurinsky hilly-ridge district:

b) Sarinsky-Guberlinsky low-mountain district:

c) Tanalyksko-Iriklinsky remnant-hilly district:

1.3.2. South Steppe sub-province of the Sub-Ural Plateau:
a) Burtinsko-Aktykyl low-mountain ridge-ridge district:

1.4. Steppe province of the Trans-Ural Plateau:
1.4.1. Ural-Tobolsk steppe subprovince:
a) Uralo-Tobolsk high-plain district:

1.4.2. Orsk-Mugodzhar dry steppe subprovince:
a) Orsko-Kumaksky hilly-ridged district:

The Turgai Plain Country includes:
1. North Turgai dry steppe province:
a) Zhetykolsko-Aiken endorheic-lake region.
1. 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 (Afanas'eva E.A., 1946).

Figure 6. Physical-geographical zoning of the Orenburg region (Afanas'eva E.A., 1946)

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 rivers, erosion is developed quite intensively, therefore, when the natural vegetation cover is destroyed, anti-erosion measures must be taken into account (Gerasimov I.P., 1933).
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 - crystalline schists, conglomerates, greenstone rocks, marl and sandy deposits - have undergone erosion and leveling. 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 chernozems. The soil cover is homogeneous. Soils are highly fertile. Most of the surface is plowed up, only in some places are 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 bedrock comes 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 (Afanas'eva E.A., 1946).
2. Steppe
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 trend. The 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 influence of the chemical and mechanical composition of parent rocks is manifested in the appearance in this subzone of low-humus leached chernozems on light rocks and residual carbonate chernozems on carbonate rocks. Solonetz phenomena in the soils of this subzone are weakly expressed.
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: on higher surfaces, ordinary chernozems are noted, and on low surfaces, chernozems transitional to southern ones. 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 (Afanas'eva E.A., 1946).
The Common Syrt region of ordinary chernozems occupies the northeastern part of the Common 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 (Afanas'eva E.A., 1946).
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 (Gerasimov I.P., 1933).
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 (L.I. Prasolov, 1939).
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 the 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 massifs 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 (Afanas'eva E.A., 1946).
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 (Prasolov L.I., 1939).
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 wide Ural 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 + B horizons varies 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 gives a great effect (Afanas'eva E.A., 1946).
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%) (Afanas'eva E.A., 1946).
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 growth properties (Neustruev S.S., 1950).
3. 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.
On 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 (Prasolov L.I., Antipov-Karataev I.N., 1939).
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, alkaline soils and rock outcrops - determine the direction of agriculture in the region. Basically, this is a livestock area (Neustruev S.S., 1950).
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 (Prasolov LI, 1939).
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 is different: from 1 to 10 km (Gerasimov I.P., 1933).
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 (Gerasimov IP, 1933).
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 growing dryness of the climate to the south in the floodplain
etc.................

Soil pollution in the Orenburg region

1. Soil cover of the Orenburg region

soil earth monitoring pollution

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

1.1 State monitoring of land, analysis of the qualitative state of land