Proverbs and sayings about May HORIZONTALLY: 2. May will deceive - in ... will leave.4 ....
The soil cover is rightly called by many researchers a "work" of the landscape. Indeed, there is not a single component of the landscape that does not affect soils. Particularly close relationships exist between soils, on the one hand, and vegetation and climate, on the other. It is no coincidence that V. V. Dokuchaev, the creator of genetic soil science, was at the same time the founder of the science of landscapes. The students of V. V. Dokuchaev, S. S. Neustruev, L. I. Prasolov, B. B. Polynov, and others, made a major contribution to the study of soils and landscapes in the USSR.
The most general regularity for the soil cover is the latitudinal zonality of its location on the plains and the altitudinal zonality in the mountains.
The latitudinal zonality of soils is well traced only in the western half of the USSR, where low plains and lowlands extend south to the border mountain ranges. To the east of the Yenisei, the latitudinal zonality of soils is strongly disturbed by mountainous relief.
From north to south on the plains of our country, the following types of soil replace one another:
tundra soils distributed on the Arctic islands and the coast of the Arctic Ocean. Formed in a cold and humid climate, under the cover of moss-lichen or sparse herbaceous and shrubby vegetation, tundra soils are characterized by low thickness, low humus content, coarse mechanical composition and waterlogging. For agricultural development, the main disadvantages of these soils are their low temperature and poverty. nutrients. The introduction of organic and mineral fertilizers and drainage increase the fertility of tundra soils. Drained, they warm up better, the permafrost under them lies deeper in summer than under swampy soils.
Podzolic and sod-podzolic soils represent the most common soil type: together with mountain podzolic soils, they occupy more than half of the entire territory of the USSR.
The formation of podzolic soils occurs under coniferous and mixed forests under conditions of a positive moisture balance (exceeding precipitation over evaporation). Therefore, they are characterized by an energetic flow of removal processes and a clearly defined washout horizon.
The zone of podzolic soils is also a zone of widespread bog soils, which occupy about one-fifth of the territory here.
In the south of the forest zone, where coniferous forests are clarified by an admixture of deciduous species and the grass cover begins to take part in the accumulation of humus, typical podzolic soils give way to soddy-podzolic soils. In soddy-podzolic soils, the amount of humus increases and a lumpy structure appears, which typical podzols lack.
Without exception, all podzolic soils need organic and mineral fertilizers. Good results are obtained by liming, enriching the soil with calcium. Bog soils are dried before plowing.
gray forest soils forest-steppe zone are common at the junction of podzolic soils with chernozems. They form under the deciduous forests of the northern forest-steppe on loess-like soils. The neutral balance of moisture, characteristic of the north of the forest-steppe, affects soil processes: the removal characteristic of podzols weakens here and, on the contrary, the humus-accumulative process intensifies, reaching its maximum expression in chernozems.
Gray forest soils are classified into three subtypes: light gray, gray and dark gray forest soils. Morphologically, they resemble podzols; like the latter, they have a washout horizon. At the same time, the increased content of humus and the presence of a nutty structure partly bring together gray forest soils, especially their dark gray subtype, with chernozems.
Such a duality in the nature of gray forest soils gave rise to various hypotheses about their origin. V. V. Dokuchaev considered gray forest soils to be zonal soils, a product of the modern landscape of the northern loes-steppe. Kazan botanical geographer S. I. Korzhinsky in the late 80s of the last century put forward a hypothesis according to which gray forest soils were formed as a result of the degradation of chernozems under forests advancing on the steppe from the north. In contrast to this, V. R. Williams argued that gray forest soils arose as a result of black earthing (progradation) of podzols under the influence of steppe vegetation advancing on the forest.
For a long time, the hypothesis of S.I. Korzhinsky about the degradation of chernozems under forests dominated the literature. At present, many researchers have abandoned it, since it was found that gray forest soils do not contain signs indicating that they passed through the chernozem stage in the past. It has also been proven that modern processes soil formations under deciduous forests in the southern forest steppe lead to the formation of not only gray forest soils, but also "forest" leached chernozems. Thus, the old point of view of V. V. Dokuchaev on gray forest soils as a modern zonal formation was confirmed.
To the south of the gray forest soils is a wide strip stretching from the Carpathians to the Altai; lie chernozems. To the east of Altai, chernozems are found as separate islands extending to eastern Transbaikalia inclusive.
VV Dokuchaev called chernozem the king of soils. Indeed, chernozems are rich in humus, have considerable thickness, have a dense granular structure and, as a result of these properties, are highly fertile. Chernozems are soils of open grassy steppes. There is an excess of plant material for the formation of humus, the removal processes are weakened, since the moisture balance is negative and continuous deep wetting of the soil is observed only in early spring and late autumn; loess-like soils enrich the absorbing soil complex with calcium, which fixes humus in the soil, hindering its removal by circulating solutions.
The properties of chernozems change significantly when moving from north to south. The northern edge of the chernozem zone is formed by podzolized(degraded) and leached chernozems. Possessing a significant content of humus, they have a number of features indicating the vigorous course of the removal processes. In leached chernozems, which are morphologically indistinguishable from typical ones, leaching processes are expressed in the fact that the horizon of carbonate accumulation (the ebullition horizon) is located not in the humus horizon, but somewhat below it, at. transition of soils into the parent rock. In the center of the zone are typical thick chernozems- the most fertile subtype of chernozem soils. The thickness and content of humus in typical thick chernozems reach their maximum. South of here, in the distribution area ordinary(medium humus) and southern(low-humus) chernozems, the humus content and the thickness of the humus horizons decrease and, moreover, more sharply than when moving north from typical thick chernozems.
Salt soils begin to play a significant role in the chernozem zone. They are represented by solods in depressions, as well as solonetzes in the southern half of the zone.
Chernozems occupy an area of about 1.9 million km 3 in the USSR, or 8.6% of the entire territory of the country. Almost half of the world area of chernozems is located within the USSR. Due to their fertility, chernozems are plowed up and involved in agricultural use more than any other type of soil. In the Trans-Volga region and Siberia, the last large massifs of virgin chernozems were plowed up quite recently, during the development of virgin lands in 1954-1956.
In dry steppes and semi-deserts, a zonal soil cover is formed chestnut soils. Their formation occurs under conditions of a pronounced negative balance of moisture and sparse grass and wormwood-grass herbage. Compared to chernozems, they are much poorer in humus, have less thickness and are more saline. Salt licks are widespread in the zone of chestnut soils, solonchaks are less common.
There are dark chestnut, chestnut and light chestnut soils. Of these, dark chestnut varieties are more fertile, bordering in the north with chernozems. V last years dark chestnut soils in the east of the country were subjected to increased plowing. However, their continuous plowing is not always possible due to salinity. Light chestnut soils are developed in semi-deserts, where agriculture becomes impossible without artificial and estuary (in the north) irrigation.
In the transition from semi-deserts to deserts appear brown soil, then, already in the deserts, - gray-brown soil and serozems. All of them are very poor in humus and are often interrupted by vast tracts of solonchaks. Salt marshes are just as characteristic of sierozem soils as solonetzes are for light chestnut soils and solods are for chernozem soils. Takyrs are a peculiar type of desert soils. These are clayey soils of depressions, with impassable mud in wet times and a crust as hard as a shard in dry times. The physical and chemical properties of takyrs are so unfavorable that they are completely devoid of vegetation, except for algae.
The southernmost zonal soil type in the USSR - red soils. In a more or less typical form, red soils are found only in Colchis and Lankaran, occupying the lower parts of the mountain slopes here. The total area of red soils in the USSR is only 3,000 km2.
Krasnozems - moist soils subtropical forests. They have great power and contain a lot of oxides of iron and aluminum. They owe their red color to iron compounds. By their age, the red soils are among the most ancient soils of the USSR, developing without interruption from the Tertiary to the present day. The physical and chemical properties of red soils are favorable for the development of many subtropical crops, including tea.
In Western Georgia and Lankaran, there are other soils of humid subtropical forests - zheltozems. They differ from red soils in their paler, yellowish color and low thickness.
In recent years, peculiar features of the processes of soil formation in the dry subtropics have been established. In addition to typical serozems, here under dry low-growing broad-leaved forests, light forests and shrub thickets in the lower part of the slopes of the mountains of Central Asia and the Caucasus, brown soils. These brown soils higher in the mountains under more humid, tall, broad-leaved forests turn into brown forest soils, and lower, on the plains of Eastern Transcaucasia, they are replaced by taupe soils similar in properties to serozems.
A review of zonal soil types from tundra to gray soils shows that the most fertile soils with optimal conditions for the development of the humus-accumulative process are located in the center of the chernozem zone. To the north and south of this strip, fertility and the intensity of the humus-accumulative process decrease, being complicated by waterlogging in the north and salinization in the south. This pattern is clearly seen in the change in humus reserves in a meter-long soil layer.
Along with latitudinal, zonal differences in the soil cover, there are longitudinal, provincial differences associated with changes in climate, vegetation, topography, and other soil-forming substances when moving from west to east. As an example, let us trace the provincial soil differences in the chernozem zone.
In the extreme west of the zone, in Ukraine, in conditions of a mild humid climate, on loose loess, chernozems are developed, which are distinguished by their high thickness and low humus content. In the east of the Russian Plain, where the climate is more continental, and eluvial-deluvial carbonate clays serve as parent rocks, thin, but exceptionally rich in humus (up to 15-17%) chernozems are formed. The chernozem zone of Western Siberia is characterized by increased salinity, the presence of meadow-chernozem and bog soils, the fragile structure and linguistic character of chernozems. The last sign - linguisticity - best reflects the continental climate of Siberia, since its occurrence is due to cracks that cut through the soil during summer droughts and winter frosts.
In the mountains, the soil cover is subject to a special law of altitudinal zonality. It is expressed the better, the greater the height of the mountains. However, for the manifestation of the altitudinal zonality of soils, not only the height of the mountains, but also the geographical latitude is important. In the tundra zone, no matter how high the mountains are, one cannot find soils other than tundra. On the contrary, in the south, within the same mountainous country, there is a striking variety of soil types.
The altitudinal zoning of soils in the Caucasus is very well expressed. If you move from the lower reaches of the Kuban to Elbrus, you will have to cross at least five high-altitude soil zones: the zone of leached chernozems on the Kuban plain; a zone of podzolized chernozems and gray forest soils in the foothill zone: a zone of mountain forest brown and partly mountain podzolic soils under broad-leaved and dark coniferous forests; zone of mountain-meadow soils of the subalpine and alpine belts.
Let us note here the main features of brown mountain forest and mountain meadow soils.
Brown mountain forest soils, in addition to the Caucasus, they are known in the Carpathians and Crimea. Being formed under broad-leaved forests with sufficient moisture, they differ in many respects from podzolic soils. common feature for brown mountain forest soils, there is a weak degree of podzolization, the presence of a nutty structure and a significant content of humus (from 4 to 12%).
Genetically, brown forest soils represent a transition from forest soils of the temperate zone to subtropical soils - krasnozems.
Mountain meadow soils characteristic of the subalpine zone with its meadows, thickets of shrubs and increased moisture.
Specific traits they are dark in color, rich in humus, leached, thin and skeletal in the lower horizons.
Each mountainous country has its own altitudinal soil zonality. And if we compare the mountains of the Caucasus with the mountains of Central Asia, it is not difficult to notice sharp differences in their altitudinal soil zonality, although both mountains are located at the same geographical latitude and have equally high altitudes. Mountain forest brown and mountain podzolic soils, widespread in the Caucasus, do not form a continuous altitudinal belt in the mountains of Central Asia. Mountain chernozems in Central Asia are in direct contact with mountain-meadow soils, in the zone of contact of which a meadow-forest zone is developed with islands of deciduous forests on brown soils. As a result of the sharply continental climate in the mountains of Central Asia, forest soils of a humid climate fall out, instead of them soils of dry steppes dominate - chestnut and chernozems.
A comparison of the soils of the Caucasus and the mountains of Central Asia suggests that the two factors that determine the altitudinal soil zonality - the height of the mountains and the geographical latitude at which they are located - should be supplemented by a third: the physical and geographical environment surrounding the mountains. Due to this last factor, the altitudinal zonation of soils can vary significantly even within the same mountainous country. For example, Eastern Transcaucasia, with its serozems on the Kura-Araks lowland, has a completely different sequence of high-altitude soil zones in the mountains than Western Transcaucasia, which is covered on the plains with alluvial-marsh soils and red soils in the foothills.
Alluvial soils of river floodplains and fluttering sands are distinguished into special groups. Floodplain soils are young, continuing to form before our eyes. For the most part, they are fertile and are successfully used for growing vegetables and valuable industrial crops. The blown sands are deprived of a developed soil cover and are difficult for economic development. Significant areas of waving sands are known in deserts, semi-deserts and on floodplain terraces of some rivers in the forest-steppe and steppe zones. In the natural state, sands in all soil zones are fixed by vegetation, and their waving is the result of economic activity human (immoderate grazing, sometimes plowing, etc.).
In conclusion, we present data on the areas occupied by the main types of soils on the territory of the USSR (Vilensky D. G., 1954).
Soils are the most important national wealth, the basis for the development of agriculture. A significant percentage of them have long been plowed up, involved in culture. The plowing of the western chernozem zone reaches 80%. Under the influence of long-term tillage, the soil has largely lost its virgin appearance. In the pre-revolutionary past, with low agricultural technology, they gradually lost their nutrient reserves, their structure was destroyed.
To improve soil fertility in the Soviet Union, various agrotechnical and reclamation measures are used: multi-field crop rotations with grass sowing; fertilizer application; drainage of wetlands; soil irrigation in dry areas; on hills with a dissected relief, work is underway to reduce the processes of soil erosion and erosion. As a result of all these activities, cultivated soils in the Soviet Union have in many cases become more fertile than their virgin counterparts. The foregoing is especially true in relation to those types of soils, the natural fertility of which is at a low level (podzolic, marsh, etc.).
Each region of our country has its own types of soils. Their formation was influenced not only by climate, relief, but also by vegetation and animal world. Today we will talk about the types of soils, about what crops can be grown on them.
What is soil?
The first who began to deal with the issue of studying the soil was the Soviet scientist V.V. Dokuchaev. He found that each region has its own soil types. After much research, the scientist concluded how the terrain, vegetation, animals, The groundwater affect the fertility of the land of a particular region. And, based on this, he proposed his classification. They were given complete characteristic soils.
Of course, each country is guided by an international or its own, local table of differentiation of the upper layer of the earth. But today we will consider precisely Dokuchaev's classification.
Soil varieties and plants suitable for them
Characteristics of sandy soils
Sandy loamy soils are another type of soil that are favorable for growing. cultivated plants. What is the nature of this type of land?
Due to its light structure, such earth perfectly passes air and water through itself. It is also worth noting that it retains moisture and some minerals well. Thus, sandy loamy soils can enrich all plants growing in them.
During rains or watering, such earth quickly absorbs water and does not form a crust on its surface.
Sandy soils warm up quickly. Thus already in early spring they can be used as soil for planting seeds or planting cuttings.
In order for your land to become more fertile, it is recommended to add peat to it. It will help improve the structure of this soil. As for nutrients, to enrich the land with them, it is necessary to add compost or manure to it. This must be done frequently. As a rule, summer residents add humus prepared and diluted with water to the roots of plants, which ensures rapid growth and enrichment with minerals and nutrients.
How can soil fertility be determined?
We have already figured out that all types of soils differ from each other not only in composition, but also in suitability for growing certain plants in them. But is it possible to determine the fertility of the land in your country house on your own? Yes, it's possible.
First of all, you must understand that the amount of nutrient minerals in the earth depends on acidity. Therefore, in order to determine whether it is necessary to improve its composition or not by adding fertilizers, it is necessary to know its acidity. The norm for all soils is pH 7. Such land perfectly absorbs the necessary nutrients and enriches all plants growing in it with them.
So, in order to determine the pH of the soil, it is necessary to use a special indicator. But, as practice shows, sometimes this method is not reliable, since the result is not always true. Therefore, experts recommend collecting a small amount of soil in different places of the dacha and taking it to the laboratory for analysis.
The sum of active air temperatures varies from 4000 to 8000 °C, the growing season is from 200 to 365 days. Thermal resources allow two full crops per year to be grown. The energy supplied to the land surface is the main, but not the only factor in soil formation. Equally important is the degree of atmospheric moisture in the area. Various combinations solar energy and precipitation determine the distribution of soil types over the earth's surface. Within the same thermal belt, zonal soils are represented by several types in accordance with the moisture content of the territory and the nature of the vegetation. The change of landscapes and soils in the subtropics is mainly due to moisture, which decreases with distance from the ocean coasts.
The agricultural development of the subtropical zone is 17%. The soils of arid and humid regions are most plowed up - brown soils, red soils and yellow soils, black merged and floodplain soils. In semi-desert and desert areas, the main agricultural areas are confined to gray soils and floodplain soils. In the valleys of the Nile, Tigris, Indus, the most ancient centers of agricultural culture arose. The subtropical belt has a wide range of agricultural plants: wheat, cotton, grapes, citrus, fruit, nut and other crops.
Subtropical rainforest areas are areas that receive between 1000 and 2500 mm of precipitation per year. The most significant in terms of area are the North American and East Asian regions. The soil cover is dominated by zheltozems and red soils. In the southern hemisphere, the area of \u200b\u200bhumid subtropics is much smaller; two regions are distinguished - South American and Australian. The soil cover of the South American region is dominated by red soils under coniferous and coniferous-deciduous forests and reddish-black soils - rubrozems under tall-grass subtropical prairies. In rubrozems, weak ferrallitization is combined with intense humus accumulation; the water regime is flushing and carbonates are absent in the profile. Reddish-black soils are also found in the North American subtropical region, in its western less humid part, on the border with dry subtropics. The Australian humid-forest region is characterized by mountainous relief and the predominance of zheltozems and yellow-brown soils. The hydromorphic soils of the humid-forest subtropical regions are yellow earth-gley, meadow, marsh, and alluvial.
The largest massifs of these soils are confined to the eastern oceanic sectors of the continents. In Eurasia, krasnozems and zheltozems are common in the south of Korea and Japan, in Central and Southeast China. In North America, they occupy the southern Appalachians and adjacent plains, as well as the most well-drained areas on the Florida peninsula. In the southern hemisphere, yellow earths and red earths are common in the mountain belt of Eastern Australia, in the northeast of Tasmania, on the North Island of New Zealand and on the extreme southeast coast of Africa. In the subtropical zone of the western sectors of the continents, krasnozems and zheltozems occur locally, in special orographic conditions and in a fairly humid climate; in southern Bulgaria, Yugoslavia, on the Black Sea coast of the Caucasus in Adzharia and Abkhazia, on the Lankaran lowland.
There is a lot of precipitation (1000-3000 mm), mild winters, moderately hot summers. The biomass of forests consisting of oak, beech, hornbeam, maple, chestnut, vines, wild grapes, ferns - more than 400 t/ha, litter - 21 t/ha, up to 0.7 t/ha of ash elements.
These films, like color, are inherited by krasnozems from soil-forming rocks.
Intense weathering leads to the decomposition of almost all primary minerals with the formation of mainly kaolinite and halloysite. Two soil-forming processes dominate: humus-accumulative and eluvial (podzolic type).
Under a layer of weakly decomposed forest litter lies a humus (up to 12% humus) horizon 10-15 cm, gray-brown with a reddish tint and a lumpy structure. Next is Mt. B brownish red, dense, with clay streaks, 50-60 cm thick. Horizon C is red with whitish spots and ferromanganese nodules.
These soils are low in calcium, magnesium, potassium and sodium, leached from weathering products and high content gland. The reaction of the environment is acidic throughout the profile, humus - up to 8%. Fulvic acids predominate over humic acids. The removal of elements down the profile is partially compensated by significant fall and the influx of ash elements during its decomposition. Physical properties favorable due to high water permeability and moisture capacity with a well-defined water-resistant structure.
Zheltozems are formed on argillaceous shales and clays with poor water permeability; therefore, processes of surface gleying and the formation of ferruginous oxide nodules take place. Usually found in the foothills and lower parts of the slopes of low mountains. Lessivage is often observed. The profile has good differentiation according to the Ao-A1-A2-B-C type. In horizon B and below, yellow coloration and high clay content dominate. The absorption capacity is relatively low for such conditions - 5-10 and up to 20 cmol / kg, although calcium predominates. Very high acidity throughout the profile, significant accumulation of ferruginous nodules in the lower part of the profile. The content of humus, predominantly fulvate, is from 5-6% in A1 with a sharp drop down. Physical properties due to the smaller amount of sesquioxides are worse than in krasnozems.
The soils of the humid subtropics are poor in nitrogen and ash elements; to increase their fertility, the use of organic and mineral fertilizers, especially phosphate fertilizers, is very important. After deforestation, erosion develops vigorously, therefore, anti-erosion measures are extremely important. Krasnozems and zheltozems are the most valuable soils for tea, tobacco, essential oil and citrus crops. A lot is applied for citrus fruits - up to 350 kg/ha of a.i. phosphate fertilizers, up to 250 kg/ha a.i. nitrogen, up to
150 kg/ha of potash fertilizers, lime. On tea plantations, an acidic reaction is optimal.
Brown soils. Brunizems
Subtropical arid xerophyte-forest and shrub-steppe areas are common on all continents. Almost all of them have a complex relief: mountain ranges, plateaus, plateaus and intermountain depressions alternate. Horizontal soil zones for the most part not expressed, but dominated by mountain zonality. The soil cover is dominated by brown, red-brown and gray-brown soils.
Brown and red-brown soils are widespread in the dry subtropics of the Mediterranean in southern Europe and northwestern Africa, in Mexico, California, in Central Chile, in South Africa, South and Southeast Australia. Small areas of brown soils are found in subtropical mountain regions. East Asia, in the Western Tien Shan and Pamir-Alai, in the Kopetdag, Crimea and in the dry subtropics of Transcaucasia.
They are formed mainly on siallitic-carbonate weathering crusts, with brown soils occurring under low-growing sparse xerophytic forests, and gray-brown soils under shrub subtropical steppes. They are characterized by non-flushing water regime in conditions of a variable-humid Mediterranean type of climate, which is characterized by dry, hot summers and humid warm winter with very little or no snow cover. With a significant amount of precipitation - 600-700 mm, a wet winter season with a temperature of +10 to -3 ° C and a dry summer season are clearly distinguished. Soils are usually non-freezing, formed under dry forests of oak, laurel, maritime pine, juniper tree, shiblyak, maquis, that is, high-ash vegetation. These soils experience the influence of sharply different hydrothermal regimes during the year.
During the winter humid and relatively warm period, intensive weathering of primary and formation of secondary clay minerals of hydromicaceous-montmorillonite-illite composition takes place. Movable weathering products in wet winter period washed out of upper parts soil thickness to a greater or lesser (depending on the amount of precipitation) depth. Usually, easily soluble salts (chlorides, sulfates) are completely removed from the soil profile, while less soluble calcium carbonates are deposited at a depth of 30-50 cm or more and form a carbonate illuvial horizon. There are processes of humification and, to a large extent, mineralization plant residues in a neutral or slightly alkaline environment, rich in bases.
During a hot and rainless summer, the weathering processes slow down significantly, especially in the upper, driest horizon. At a certain depth, where the soil is less dry, these processes continue during the summer, so the most clayey is not the uppermost soil horizon, but the horizon at a depth of 30-80 cm.
The drying of the soil surface causes the pulling of film moisture and dissolved substances from deeper layers. When moisture evaporates, dissolved substances and, in particular, calcium carbonates crystallize, filling the capillary gaps in the soil column above the carbonate nodule horizon. Neoplasms of calcium carbonates have the form of the thinnest white mold or pseudomycelium. During the winter rainy period, when the soil is washed with water saturated with carbon dioxide, the carbonate mold dissolves again and is pushed back into the deeper parts of the profile.
During dry and hot summers, the processes of mineralization of dry matter slow down, which contributes to the polymerization and preservation of humic substances in soils, so the humus content in brown soils is usually 4-7, less often up to 10%, and in gray-brown soils it is 2.5- 4% with a significant predominance of the group of humic acids (Cr / Cf -1.5-2.0). The iron oxides released during weathering are dehydrated during the dry period. This gives the soil a reddish-brown hue, especially bright in the horizon of maximum claying.
There are no thick glacial rocks of the boreal belt, or accumulations of loess and loess-like rocks of the subboreal zone. Pleistocene rocks of small thickness are the main soil-forming rocks. Limestones are frequent, where the A 1 soil layer directly overlies the limestone layer. There are eroded and redeposited red-colored weathering crusts of igneous and metamorphic rocks. Dust materials enter through the atmosphere. The rocks are usually heavily karst, fissured, which contributes to good drainage and exacerbates aridity. Groundwater lies far away and does not affect the processes of soil formation.
At the beginning of the Pleistocene, vigorous erosion of red-colored weathering products took place, finely elutriated accumulations of which were deposited on the surface of limestones. These deposits are called "terra rossa" (red earth). They are especially common on the Adriatic coast of the Balkan Peninsula. Similarly, later accumulations of brown clays, called terra fusca, arose.
The humus horizon of brown soils has Brown color, lumpy structure, thickness 20-30 cm. Deeper is a compacted horizon, often carbonate B. Even lower lies C, often rocky. In particular, on the southern coast of the Crimea, soils 20-30 cm thick occur in Mesozoic shales, often involved in the soil due to plantation. A typical soil profile looks like: A 1 -Bm-Bca-C.
Brown soils are characterized by a slow decrease in humus down the profile, a slightly acidic and neutral (often alkaline in the lower horizons) reaction of the medium, and a high cation exchange capacity (25–40 cmol/kg) with a predominance of calcium and magnesium. There is no profile differentiation by chemical composition. They are distinguished by high biological activity, especially in spring and autumn, up to 40 million / g of soil microorganisms. The hydrothermal regime promotes deep weathering of primary minerals. Water-physical properties are relatively favorable.
In brown soils, the total content of nitrogen and phosphorus is high, but mobile forms of phosphorus are not enough in them. In the legend to the soil map of the world, brown soils are assigned to the group of cambisols. In general, the soils of the arid subtropics are highly fertile and are widely used for agriculture (wheat, corn), vineyards, citrus and other orchards, and olive plantations. The destruction of natural vegetation provoked severe soil erosion - many granaries of the times of the Roman Empire (Syria, Algeria) became deserted steppes. In Spain, Portugal, Greece, up to 90% of brown soils are affected by erosion. Many areas are in need of irrigation.
The wider use of these soils is hindered by dry summer period during which many crops require watering, mountainous relief where farming is often impossible and horticulture and viticulture cause severe soil erosion. Gray-brown soils in flat terrain are used in agriculture and horticulture. In areas where the winter period is frost-free, they usually grow two crops a year: in winter, without irrigation, cereals (for example, wheat), and in summer, with irrigation, more heat-loving crops (rice, cotton, tobacco, melons). Often gray-brown soils are used for orchards and vineyards.
Brunizems are high-humus chernozem-like soils, leached in the upper part of the profile, with a Bt textural horizon and signs of gleying in the lower part, with a groundwater level of 1.5-5 m. These are prairie and pampas soils. They are formed in a moderately cold subtropical climate with 600-1000 mm of precipitation, average January temperatures from -8 to +4 °С, July - 20-26 °С. More than 75% of precipitation falls in the summer in the form of showers. The moisture coefficient is more than 1. There is a periodically flushing water regime that maintains relatively high level groundwater in watersheds. V South America they distinguish rubrezems, which differ from brunizems in a reddish color, but are very close to them in morphology and soil properties.
Brunizems are formed in a flat or slightly hilly relief on loess and carbonate moraine loams and clays. Natural vegetation - perennial high (up to 1.5 m) cereals with a deep root system. Above-ground phytomass 5-6 t/ha, underground - 18 t/ha. In terms of properties, brunizems are close to chernozems, but are more leached, often acidic on top, and do not have salt horizons. Among the exchange cations, calcium always predominates, but the proportion of hydrogen can also be quite large. In the northeast of the United States, humus has up to 10%, and in the southwest of the range - 3%.
Brunizems are characterized by intense clay formation due to the weathering of primary minerals; montmorillonite and illite predominate. The age is usually 16-18 thousand years, that is, it is significantly older than the chernozems. The soil-forming process is characterized by humus accumulation, removal of easily soluble compounds and silt; the introduction of elements with a capillary border of soil and groundwater. Brunizems - the most fertile soils USA. Almost all of them are plowed up, used for crops of corn and soybeans (“Corn Belt”). With long-term operation, they lose humus, structure, porosity, and are subject to erosion.
The soil cover of Russia is very diverse. Despite the huge - 17.1 million km2 - productive make up only 13% of its total area.
Podzolic soils are the most common type. They occupy an area of 7 million km2, which is 40.9% of the total soil area.
The sown area in Russia in 1997 reaches 133.5 million hectares, or 8% of the area of land resources. The soil mass is also large, reaching 1.53 million km2, which is 8.6% of the soil area of the USSR and 48% of the world area of chernozem soils. The sown areas in Russia increased sharply after the plowing of virgin and fallow lands. Their area for 1954-1960 amounted to 19.7 million hectares, which made it possible by 1966 to increase the area of arable land to 122.6 million hectares. In 1913, the sown area was 69.8 million hectares. In the arid regions of the Cis-Urals, Northern, Lower, and significant work has been carried out to develop irrigated agriculture. As a result, the area of irrigated land reached 1.6 million hectares in 1976, which made it possible to solve the problems of growing rice, grain, industrial, as well as vegetable crops. Drainage reclamation measures were also widely carried out. The areas of drained lands reach more than 3 million hectares.
The ongoing agrotechnical measures, mechanization and chemicalization of production made it possible to grow significant amounts of grain. Thus, in 1997 the grain harvest reached 84 million tons. In 1966, it was 99.9 million tons, while harvesting in 1913 - 50.5 million tons.
natural fertility soil resources Russia allows you to fully meet the needs of its population in food and ensure food security and independence of the country.
Among the most important natural resources refers to the earth. It hosts all sectors of the economy, cities, villages and towns. It is the most important factor in agricultural production. With its help, most of the food and a significant part of the raw materials for are obtained.
They occupy a large area in our country. It is customary to call meadows tracts of land occupied by grassy. Usually meadows are used as hayfields and pastures. Russia has about 40 million hectares of hayfields and over 230 million hectares of pastures. The most significant area of valuable meadows is in the forest zone, where they grow on the site of cut down forests, on abandoned arable lands and on floodplains.
In all geographical areas the destruction of grass cover is accompanied by a number of unfavorable processes. The vegetation cover is easily destroyed under the wheels and caterpillars. After the destruction of vegetation, it degrades, soil subsidence and soil destruction occur.
The meadows are located mainly along the beams and valleys. When overgrazing on the slopes, paths carved by cattle appear, devoid of any vegetation. They contribute to the formation of various kinds of mud and. In semi-deserts, overgrazing easily leads to the degradation of fescue pastures and their replacement by less valuable wormwood pastures. As a result of immoderate grazing, vegetation is completely destroyed and mobile sands are formed, sand storms are intensifying.
Diverse natural conditions on the territory of our country. Depending on the climate, vegetation, geological structure The soil cover is also changing. The change of soil types from the northwest to the southeast, i.e., latitudinal zonality, is most clearly expressed. In the mountains, soil types change from the foot to the peaks, i.e., vertical zonality is observed.
The main types of soils. Top left to right: podzolic soil, gray forest soil, black soil, chestnut soil. Bottom left to right: solonetz, solonchak, serozem, krasnozem.
Tundra gley soils are the main soil type in the tundra. The zone of these soils extends north of the Arctic Circle, along the Kola Peninsula, occupies the northern part of the Arkhangelsk region and the Komi Republic, and in Siberia - at the latitude of the Arctic Circle to the Yamal Peninsula, along the coast of the Arctic Ocean and further east to the Kamchatka Peninsula. Tundra gley soils (together with arctic soils) occupy about 6% of the entire territory of Russia.
Tundra soils are thin, acidic (see Soil acidity), poor in nutrients. They contain up to 5% humus, their surface is covered with a layer of peat. The biological activity of these soils is very weak; permafrost occurs at shallow depths. On well-cultivated and fertilized tundra soils, barley, oats, cabbage, and potatoes are grown. The natural vegetation of the tundra is also used for reindeer grazing.
The zone of podzolic, including sod-podzolic, soils is located south of the tundra. It stretches in a wide strip from west to east to the coast Sea of Okhotsk. This type occupies about 30% of the country's territory. Podzolic soils were formed under coniferous and mixed forests under conditions of sufficient moisture. The forest litter (the upper horizon of these soils), which consists of litter (needles, leaves, branches, etc.), is decomposed by microorganisms. In this case, organic acids are formed, which, interacting with the mineral particles of the soil, cause their decay and removal to the lower horizon. This creates an acidic podzolic horizon depleted in nutrients, consisting mainly of barren whitish silica, saturated with iron, aluminum, and magnesium. Below the podzolic horizon, an illuvial horizon is formed, where silty and colloidal soil particles, humus substances and various compounds, mainly iron, washed out from the upper layer accumulate. They give this horizon a reddish-brown color.
The most fertile among podzolic soils are soddy-podzolic soils that form under mixed and deciduous forests. When plant residues decompose, humus is formed. As a result, a humus (humus) horizon is formed at the top, consisting of humus, mineral compounds and undecomposed plant residues. It has a dark color. The more powerful the humus horizon, the higher the fertility of the soddy-podzolic soil. The thickness of the humus horizon in soddy-podzolic soils ranges from a few centimeters to 15–20 cm, and the thickness of the podzolic horizon varies from a few centimeters to 20 cm, sometimes more. The content of humus in the arable layer is 1–6%.
To increase the thickness of the humus horizon and the content of humus in it, soddy-podzolic soils are deeply plowed, organic and mineral fertilizers are added to them, and lime is applied. Soddy-podzolic soils - the main arable land in the Non-Chernozem zone of the country, characterized by sufficient moisture. Increasing the fertility of these soils is the most important condition for creating guaranteed high yields crops.
The zone of gray forest soils extends as a narrow discontinuous strip from the Carpathians to Transbaikalia, south of the zone of podzolic soils.
Gray forest soils were formed under broad-leaved forests with a well-developed herbaceous cover. They combine the features of podzolic soils (the upper horizons are depleted in silt and the lower horizons are enriched in it, acid reaction) and steppe chernozems (a well-developed humus horizon).
The humus horizon of these soils is thicker and darker and contains more humus (3–9%) than those of soddy podzolic soils. Gray forest soils are characterized by rather high natural fertility and are widely used in agriculture.
Bog soils are found mainly among podzolic soils, especially in the Non-Chernozem region of Russia, Belarus, Polissya of Ukraine and the Baltic states, where there is a lot of precipitation. These soils are mostly acidic.
Swamp soils cannot be used for growing crops without prior drainage and development. With drainage, proper processing, liming and the introduction of phosphorus-potassium and copper-containing mineral fertilizers, marsh soils turn into highly fertile lands with a high content of humus and nitrogen. Peat is also widely used for fuel, for the preparation of organic fertilizers, for animal bedding.
The zone of chernozems extends in a wide strip from the southwestern borders of the country to the foothills of Altai. It includes the steppes and forest-steppes of Ukraine, the Central Black Earth regions of Russia, North Caucasus, Volga region, Western Siberia. Chernozems are the "golden fund" of our country's land resources, the most fertile soils. The formation of these soils is primarily associated with steppe vegetation and parent rocks, which contain a lot of carbonates. During the formation of chernozems, the accumulation of humic substances and mineral elements of plant nutrition occurs. Humus contributes to the creation of a water-resistant, finely cloddy soil structure. Water-soluble salts are leached and accumulate in the lower horizons of the soil profile.
Chernozems are highly fertile: they are quite air and water permeable, absorb moisture well and retain it, contain many nutrients, and have a neutral or slightly acidic reaction.
Chernozems with a humus horizon up to 65–90 cm thick are typical of the Middle Volga, Trans-Urals, Western Siberia, Northern Kazakhstan, and some other regions. The southern chernozems have a humus horizon thickness of 30–65 cm and a less pronounced structure.
Chernozem soils are almost completely plowed up. In order to maintain their fertility and increase the yield of agricultural crops, it is necessary to make mineral and organic fertilizers, apply soil protection measures, observe scientifically based agricultural technology.
Chestnut soils are located south of chernozem soils, on a large territory of the zone of dry semi-desert steppes (in the south of Ukraine and Moldova, in the North Caucasus, in Kazakhstan). Vegetation in arid regions is sparse, organic matter quickly decomposes with the formation of mineral compounds, so there is little humus in chestnut soils (1.5–5%). The humus horizon of these soils is from 15 to 50 cm. In the zone of chestnut soils, droughts and strong winds are frequent, causing the danger of wind erosion, so the fight against drought and wind erosion of soils is the basis of agriculture in this zone. To increase the fertility of chestnut soils, it is necessary to apply fertilizers, especially phosphorus ones. Many agricultural crops are cultivated on chestnut soils, mainly under irrigation.
Salt licks, solonchaks, solods, takyrs and takyr soils are common in the desert zone (Central Asia, southern Kazakhstan). They form a group of saline soils. Agriculture on them is possible mainly after the removal of excess salts from the root layer during irrigation.
Serozems are widespread in the foothill regions of Central Asia and occupy 1.5% of the country's territory. They formed under subtropical semi-desert vegetation, on rocks that consist of sediments (loesses) of rivers, and contain many nutrients. In a dry hot climate organic matter these soils are rapidly mineralized. Serozems are poor in humus (0.5–4.5%), but their fertility is quite high, since the parent rock is rich in nutrients. When irrigated, many southern crops are grown on them, primarily cotton, grapes, pomegranates, and melons.
Krasnozems - typical soils of humid subtropics Black Sea coast Caucasus and part of the coast of the Caspian Sea in Azerbaijan. Krasnozems were formed under the influence of a weak podzol-forming process, and therefore they are slightly acidic. The red color of these soils is due to the fact that they contain a lot of aluminum and iron compounds. Humus horizon - 15–20 cm, contains 5–8% humus. Krasnozems are fairly fertile soils.
The soils of the mountains are different from the plains low power and a significant content of rubble. However, some types of mountain soils are almost never found on the plain. Of these, the most common are mountain-meadow and mountain-meadow-steppe soils, which are used mainly as pastures.
