In mixed forests dend podzolic soils. What is the soil in mixed forests? Characteristics and features of the natural zone of mixed forests

The Arctic zone is characterized by the harsh climatic conditions of the Arctic climatic belt, a short cold summer and a long winter with a very low air temperature. The average monthly temperature of January -16 ... -32 ° C; July - Below + 8 ° C. This is a zone of many years of marzlot, the soil pulls into a depth of 15-30 cm. There are few precipitation - from 40 to 400 mm per year, however, due to low temperatures, precipitation exceeds evaporation, so plant communities The Arctic TundR (mainly mosses and lichens with the addition of some flowering plants) are in conditions of balanced, and sometimes even excessive moistening. The phytomass of the Arctic TundR is from 30 to 70 centners / ha, polar deserts - 1-2 c / ha.

The most common type of automorphic soil of the Arctic is arctic tundra soils. The power of the soil profile of these soils is due to the depth of seasonal thawing of the soil-ground thickness, which rarely exceeds 30 cm. The differentiation of the soil profile due to cryogenic processes is weakly expressed. In the soils formed in the most favorable conditions, only a vegetable-peat horizon (A 0) is well expressed and a low-power humus horizon is significantly worse (A 1) ( cm. Morphology of Soil).

In arctic-tundra soils due to excess atmospheric moistening and highly located surface of many years of permanent, over the short season of positive temperatures, high humidity is supported. Such soils have a weak sour or neutral reaction (5.5 to 6.6 rchot) and contain 2.5-3% humus. At relatively rapidly drying areas with a large number of flowering plants, soils are formed with a neutral reaction and an increased humus content (4-6%).

For landscapes of the Arctic desert characteristic saline. On the surface of the soil, salts are frequent, and in summer, small solonish lakes can be formed as a result of salts migration.

The TundR zone belongs mainly to the subarctic climatic belt. The climatic conditions of the tundras are characterized by a negative average temperature: from -2 to -12 ° C. The average temperature of July does not rise above + 10 ° C, and average temperature January is lowered to -30 ° C. The duration of the smokery period is about three months. For summer time is characterized by high relative humidity Air (80-90%) and continuous solar lighting. Annual precipitation is small (from 150 to 450 mm), but due to low temperatures their number exceeds evaporation.

Somewhere on the islands, and somewhere everywhere - perennial Merzlota, the soil hops to a depth of 0.2-1.6 m. The location of the dense freezing soil is close to the surface and excess atmospheric moistening causes the overalling of the soil in the smokery period and, as a result, its inching. The proximity of frozen soils is very cooling the soil thickness, which constrains the development of the soil formation process.

As part of the tundra vegetation, shrubs, shrubs, herbaceous plants, mosses and lichens are dominated. Wood forms in the tundra not. The soil microflora is quite diverse (bacteria, mushrooms, actinomycetes). Bacteria in the tundra soils is greater than in the Arctic - from 300 to 3,800 thousand in 1 g of soil.

Among the soil-forming rocks are dominated by various types of glacial sediments.

Above the surface of the multi-metered thick, the tundrov-gley soils are common, they are formed under conditions of difficult drainage of soil and groundwater and oxygen deficiency. For them, as for other types of tundra soils, the accumulation of underdeveloped plant residues is characterized, which is, in the upper part of the profile, a well-pronounced peat horizon (A T) is located, consisting mainly of organic matter. Below the peat horizon is low-power (1.5-2 cm) humus horizon (A 1) of brown-brown color. The content of humus in this horizon is about 1-3%, the reaction is close to neutral. Under the humus horizon there is a gluile soil horizon of a specific bluish-gray color, which is formed as a result of reducing processes in the conditions of water saturation of the soil strata. The guery horizon continues to the upper surface of many years of permanent. Sometimes a low-power spotted horizon with alternating gray and rusty spots is separated between humus and guery horizons. The power of the soil profile corresponds to the depth of the seasonal thawing of the soil.

In some areas, the tundra is possible agriculture. Vegetables are grown around large industrial centers: potatoes, cabbage, onions, in greenhouses - many other cultures.

Now in connection with active learning mineral wealth The North faced the problem of the protection of the nature of the tundra, and, first of all, its soil cover. The top peat horizon of the tundra soil is easily broken, and decades are required for its recovery. Traces of transport, drilling and building machines cover the surface of the tundra, contributing to the development of erosion processes. The violation of soil cover causes irreparable damage to the entire unique nature of the tundra. Strict control economic activity In the tundra - a complex, but extremely necessary task.

Taiga forests are located in a temperate climatic belt. The climatic conditions of the huge territory of the taiga belt are different, but, in general, the climate is characterized by quite large seasonal fluctuations in temperature, moderately cold or cold winter (with the average temperature of January -10 ... -30 ° C), relatively cool summer (with the average monthly temperature close to + 14 ... + 16 ° C) and the predominance of the amount of atmospheric precipitation over evaporation. In the coldest areas of the Taiga belt (east of Yenisei in Eurasia, in the north of Canada and Alaska in North America) - a long-term Merzlota, but the soil pulls off in the summer to a depth of 50 to 250 cm, so the Merzlota does not interfere with the growth of trees with a shallow root system. These climatic conditions determine the washing type of water regime in the territories that are not crushed by many years of milling. In areas with many years of milling, the washing regime is broken.

The prevailing type of vegetation zone - coniferous forestsSometimes with an admixture of hardwood trees. At the very south of the Taiga zone, clean deciduous forests are common. About 20% of the entire area of \u200b\u200bthe Taiga zone occupies a swamp vegetation, the square under the meadows is small. The biomass of coniferous forests is significant (1000-3000 c / ha), but the ODED is only a few percent of biomass (30-70ce / hectares).

A significant part of the forests of Europe and North America is destroyed, therefore the soils formed under the influence of forest vegetation, for a long time are in the conditions of flavored, modified by man landscapes.

The taiga zone is heterogeneous: the forest landscapes of different areas are significantly different in the conditions of the soil formation.

In the absence of many years of permanent, on well-permeable sandy and squealed soil rocks are formed different types podzolic soils. Structure of the profile of these soils:

A 0 - Forest litter, consisting of caps of needles, residues of trees, shrubs and mosses located at different stages of decomposition. Below, this horizon is gradually moving into the loose mass of coarse humus, at the very bottom partially mixed with debris minerals. The power of this horizon is from 2-4 to 6-8 cm. The reaction of the forest litter is strongly acidic (pH \u003d 3.5-4.0). Below in the profile, the reaction becomes less acidic (pH increases to 5.5-6.0).

A 2 - eluvial horizon (leaching horizon), from which all over or less mobile connections are made to the lower horizons. In these soils, this horizon is called podzolic . Sand, easily scattered, due to washing out pale gray, almost white. Despite the low power (from 2-4 cm in the north and in the center to 10-15 cm in the south of the Taiga zone), this horizon is dramatically highlighted in the soil profile due to its color.

B - bright brown, coffee or rusty-brown illuvial horizon, in which the washing prevails, i.e. The deposition of compounds of those chemical elements and small particles, which were washed out of the top of the soil strata (mainly from the podzolic horizon). With a depth of this horizon, a rust-and-brown shade decreases and gradually goes into the soil-forming breed. Power 30-50 cm.

C - soil-forming breed, represented by gray sand, rubble and boulders.

The power of the profile of these soils gradually increases from north to south. The soil of southern taiga has the same structure as the soils of the Northern and average taiga, but the power of all horizons is more.

In Eurasia, podzolic soils are distributed only in terms of the taiga zone to the west of Yenisei. In North America, podzolic soils are distributed in the southern part of the taiga zone. The territory of Eastern Yenisei in Eurasia (Central and Eastern Siberia) and the northern part of the Taiga zone in North America (Northern Canada and Alaska) are characterized by a continuous multi-year Merzlot, as well as the peculiarity of plant cover. Sour brown taiga soils (subburis) are formed here, sometimes referred to as the minor-taiga-taiga and tinnitoneal soils.

For these soils, a profile is characterized with an upper horizon folded with rough humus, and the absence of a clarified wilderness horizon, characteristic of podzolic soils. Profile power is small (60-100 cm), it is weakly differentiated. As well as podzolic, brown taiga soils are formed under conditions of a slow biological circulation and a small mass of plant annual cap, which almost completely enters the surface. As a result of a slow motion transformation of plant residues and a flushing mode on the surface, a torn dark brown litter is formed, from the organic matter of which easily soluble humus connections are washed. These substances are precipitated throughout the soil profile in the form of humus-oxidase-sized compounds, as a result of which the soil acquires the brown, sometimes a ocher-brown color. The humus content down the profile decreases gradually (under the humus underlining contains 8-10%; at a depth of 50 cm about 5%, at a depth of 1 m 2-3%).

Agricultural use of the soils of the taiga zone is associated with great difficulties. In the Eastern European and West Siberian Taiga, Pashnya occupy 0.1-2% of the entire area. The development of agriculture is hampered by adverse climatic conditions, strong soil roastedness, the ubiquitous wetlability of the territory, a long-term Merzlot to the east of Yenisei. More actively develops agriculture in the southern regions of the Eastern European Taiga and in the meadow-steppe areas of Yakutia.

For the effective use of taiga soil, large doses of mineral and organic fertilizers are required, the neutralization of high soil acidity, places - the removal of boulders.

In the medical and geographic attitude of the zone of taiga forests is small, since many chemical elements lose many chemical elements, including those necessary for the normal development of man and animals, therefore, in this zone, the conditions of partial deficit of a number of chemical elements (iodine, copper are created. , calcium, etc.)

The climate of mixed forests is characterized by a warmer and long summer (the average temperature of July from 16 to 24 ° C) and warmer in winter (the average temperature of January is 0 to -16 ° C) compared with the zone of taiga forests. Annual precipitation - from 500 to 1000 mm. The amount of precipitation is everywhere exceeding evaporation, which causes a well-pronounced wash water mode. Vegetation - mixed forests made of coniferous (spruce, fir, pine), fine (birch, oxne, alder, etc.) and a deciduous (oak, maple, etc.) breeds. A characteristic feature of mixed forests is more or less developed herbal cover. Biomass of mixed forests is greater than in the taiga, and is 2000-3000 c / ha. The mass of the cap also exceeds the biomass of taiga forests, but thanks to more intense microbiological activities, the depletion processes of the dead organic matter go more vigorously, therefore, in mixed forests, the litter has a smaller power than in the taiga, and more decomposed.

The zone of mixed forests has a pretty multiple soil cover. The most characteristic type of automorphic soils of mixed forests of the Eastern European Plain is the dend-podzolic soils – South species of podzolic soils. Soils are formed only on loamy soil rocks. Derne-podzolic soils have the same structure of the soil profile as podzolic. From podzolic, they differ from the lower power of the forest bedding (2-5 cm), the greater power of all horizons and a more clearly pronounced humus horizon and 1 lying under the forest underlining. The appearance of the humus horizon of turf-podzolic soils is also different from the horizon in podzolic soils, at the top it contains numerous herb roots, which often form a well-pronounced turne. Color - gray different shades, loose fringe. The power of the humus horizon is from 5 to 20 cm, the content of humus is 2-4%.

In the upper part of the profile, these soils are characterized by an acidic reaction (pH \u003d 4), with a depth of reaction gradually becomes less acidic.

The use of soil mixed forests in agriculture is higher than the soil of taiga forests. In the southern regions of the European part of Russia, there are 30-45% of the area, to the north, the share of plowed lands is significantly less. Agriculture is difficult due to an acidic reaction of these soils, their strong leaching, and in places of wetlands and worship. For neutralization of excess acidity, the soil is lime. To obtain high yields, large doses of organic and mineral fertilizers are needed.

Landscapes of large forests, favorable for a person, are exposed for a long time exposed to its part, so they are strongly changed: forest vegetation is either completely destroyed (for most of Western Europe and the USA), or replaced by secondary vegetation.

Among the soils formed in these landscapes, two types are distinguished:

1. Gray forest soils formed in intra-projectal districts (Central regions of Eurasia and North America). In Eurasia, these soils are being drawn from western borders Belarus to Transbaikalia. Gray forest soils are formed in continental climatic conditions. In Eurasia, the severity of the climate increases from the west to the east, the midranges are changed from -6 ° C in the west of the zone to -28 ° C in the east, the duration of the smokery period is from 250 to 180 days. The conditions of the summer relative to the same - the average temperature of July ranges from 19 to 20 ° C. The annual amount of precipitation changes from 500-600 mm in the west to 300 mm in the east. The soils are missed by precipitates to a greater depth, but since the groundwater in this zone is lowered deeply, then the wash water regime is not characteristic here, only in the most moistened areas there is a solid waters of the soil strata to groundwater.

The vegetation under which gray forest soils were formed, presented predominantly to wide forests with rich herbal cover. To the west of the Dnieper, this is a grab-oak forest, between the Dnieper and the Urals - Lipovo-Oak Forests, eastern Urals Within the West Siberian lowland, birch and aspen forests are dominated, larch appears even east.

The mass of the fodder of these forests significantly exceeds the mass of the fades of taiga forests and is 70-90 c / ha. Opad is rich in the ash elements, especially by calcium.

Soil-forming breeds are predominantly coating Laming Suglinki.

Favorable climatic conditions determine the development of soil fauna and microbial population. As a result of their activities, a more energetic transformation of plant residues occurs than in ferrous-podzolic soils. This causes a more powerful humus horizon. However, part of the octa is still not destroyed, but accumulates in the forest litter, the power of which is smaller than the thickness of the litter in the dend-podzolic soils.

The structure of the profile of the sulfur forest soil ( cm. Morphology of Soil):

A 0 - Forest litter of peeps of trees and herbs, usually small power (1-2 cm);

A 1 - humus horizon of gray or dark gray, fine or middle-wide structure containing a large number of herbs roots. At the bottom of the horizon, there is often a silica rash. The power of this horizon is 20-30 cm.

A 2 is a wilderness horizon, gray, with a unclearly pronounced sheet-lamellar structure and with a capacity of about 20 cm. It has small iron orders.

B - Horizon of washing, brown-drilling color, with a clearly pronounced nutty structure. Structural separateness and pore surface are covered with dark brown films, there are small iron orders. The power of this horizon is 80-100 cm.

C - soil-forming breed (coating forest-shaped loam of yellowish-brown color with a well-pronounced prismatic structure, often contains carbonate neoplasms).

The type of gray forest soils is divided into three subtypes - light gray, gray and dark gray, the names of which are associated with the intensity of the color of the humus horizon. With the darkening of the humus horizon, the power of the humus horizon increases slightly and the degree of severity of the flushing of these soils is reduced. The eluvial horizon A 2 is only in light gray and gray forest soils, there is no dark gray, although the lower part of the humus horizon A 1 has a whisper shade. The formation of subtypes of gray forest soils is due to bioclimatic conditions, so light gray forest soils are tightly to the northern areas of the gray soil strips, gray - to the median, and dark gray - to the southern.

Gray forest soils are much more fertile for turf-podzolic, they are favorable for growing grain, forage, gardening and sage and some industrial crops. The main disadvantage is strongly reduced fertility as a result of centuries-old use and considerable destruction as a result of erosion.

2. Brown forest soils were formed in territories with a soft and wet ocean climate, in Eurasia - this Western Europe, Carpathians, mountain Crimea, warm and wet areas of the Caucasus and the Primorsky Territory of Russia, in North America - the Adhesive part of the continent.

The annual precipitation is significantly (600-650 mm), but most of them fall in summer, so the wash mode is valid for short periods of time. At the same time, soft climatic conditions and significant atmospheric moistening activate the processes of conversion of organic matter. A significant mass of the octa is recycled and mixed numerous invertebrates, contributing to the formation of humus horizon. In the destruction of humus substances begins the slow movement of clay particles into the hooing horizon.

The profile of brown forest soils is characterized by a weakly differentiated and low-power not very dark humus horizon.

Profile structure:

And 1 - humus horizon of gray-brown color, humus shade gradually decreases downstairs, the structure of the company. Power - 20-25 cm.

B - Horizon of washing. Top bright brown-brown, clay, down brown shade will decrease, and the color approaches the color of the mother breed. Horizon power - 50-60 cm.

C is a soil-forming breed (Limsoid Suglink Palevoy Color, sometimes with carbonate neoplasms).

For large quantities These soils made by fertilizers and rational agrotechnology gives very high yields of various crops, in particular, the highest grain crops are obtained on these soils. In the southern regions of Germany and in France, brown soils are used mainly under the vineyards.

In Eurasia, chernozem extends a solid strip through the East European Plain, the Southern Urals and Western Siberia to Altai, east of Altai they form separate arrays. The most Eastern array is in Transbaikalia.

In North America, there is also a forest-steppe and steppes zones, west of mixed and deciduous forest areas. Submeridional strike - from the north they border the taiga zone (about 53 ° S.Sh.) and in the south reach the coast Mexican Gulf (24 ° C.Sh.), however, the chernozem soil strip is located only in the intra-engineity region and does not go to the sea coast.

In Eurasia, the climatic conditions of the zone of the spread of chernozems are characterized by the increase in continentality from the west to the east. In Western regions, winter is warm and soft (the average temperature of January -2 ... -4 ° C), and in the eastern regions - harsh and low-speed (average January -25 ... -28 ° C). From the west to the east, the number of smoke-free days decreases (from 300 in the West to 110 in the East) and the annual precipitation (from 500-600 in the West to 250-350 in the East). In the warm period, the differences in climate are smoothed. In the west zone, the average temperature of July - + 19 ... + 24 ° C, in the east - + 17 ... + 20 ° C.

In North America, the severity of the climate in the zone of the spread of chernozem soils increases from the north to south: the average temperature of January is changing from 0 ° C in the south to -16 ° C in the north, summer temperatures are the same: the average temperature of July is +16 - + 24 ° C. Annual precipitation also does not change - from 250 to 500 mm per year.

For the entire area of \u200b\u200bthe distribution of chernozem soils, evaporation is equal to the annual amount of precipitation or less. Most of the precipitation falls in summer, often in the form of a rainfall, it contributes to the fact that a significant part of precipitation is absorbed into the soil, and is removed in the form of a surface drain, therefore, for chernozem, the immense water regime is characteristic. The exception is the forest-steppe areas where the soil is periodically washed.

The soil-forming breeds of the territory of the chernozem are presented predominantly with shadow-shaped sediments (the lessisa is a fine-grained sedimentary breed of light yellow or pale color).

The chernozems were formed under herbal vegetation, the composition of which perennial cereals prevail, but now most of the black-earth steppes are destroyed and natural vegetation is destroyed.

Biomass in the natural steppe communities reaches 100-300 centners / ha, of which half the half is dying annually, as a result, in the black earth zone, much more organic substances enter the soil than in the forest zone of a moderate belt, although the biomass of forests is more than 10 times higher than . In the steppe soils of microorganisms is much larger than in forests (3-4 billion in 1 g, and for some areas and more). The intensive activity of microorganisms aimed at processing plant potholes is terminated only during periods of winter freezing and summer soil drainage. A significant number of annually incoming plant residues ensures the accumulation of large quantities of humus in black soil soils. The content of humus in chernozems from 3-4 to 14-16%, and sometimes more. A distinctive feature of the chernozem is the content of humus in the entire soil profile, and down the profile it decreases very gradually. The reaction of the soil solution of the upper part of the profile in these soils is neutral, at the bottom of the profile, starting from the illuvial horizon (B), the reaction becomes weakly alkaline.

The most characteristic feature of these soils, which caused their name, is a powerful well-developed humus horizon intensively black.

The structure of the profile of typical black soils:

A 0 - steppe felt. This horizon with a capacity of 1-3 cm consists of residual herbal vegetation and is found only on virgin lands.

A 1 - humus horizon. Its color in wet state is intense black, power - 40-60 cm. The horizon is saturated with roots of plants.

In - transitional horizon of blacknate-drone uneven color, gradually turning into the color of the soil breed. From the humus horizon, humus flows come here. At the bottom of the horizon contains significant number Calcium carbonate. The power of this horizon is 40-60 cm.

C - soil breed (lessoidal deposits).

In Eurasia, south of typical black soils are common ordinary , And even south - southern black soil. The annual rainfall decreases to the south, the total biomass and, accordingly, the mass of the vegetable oxide coming. This causes a reduction in the power of the humus horizon (in ordinary chernozem, its power is about 40 cm, in the southern - 25 cm). The properties of chernozem soils are also changing as climate continentality increases, i.e. from west to east (in Eurasia).

Chernozems are famous for their fertility, the areas of their distribution are the main base of the production of many grain, first of all wheat, as well as a number of more valuable technical crops (sugar beets, sunflower, corn). The crop on chernozem depends mainly on the water content in the form available to the plant. In our country, crust caused by droughts were characteristic of the black earth regions.

The second no less important problem of chernozem is the destruction of soil caused by erosion. At the black-earth soils used under the farming, special anti-erosion events are needed.

The medical and geographical characteristics of the chernozem is favorable. Chernozems are the standard of optimal ratio of chemical elements necessary for humans. Endemic diseases associated with the deficiency of chemical elements are not characteristic of areas of distribution of these soils.

In the arid and extracontinental conditions of dry steppes and semi-deserts are formed, respectively, brown brown desert-steppe soils.

In Eurasia, chestnut soils occupy a small area in Romania and are more widely represented in the Aridal Central Regions of Spain. The narrow strip they stretch along the coast of the Black and Azov seas. To the east (in the Lower Volga, Western Caspiani), the area of \u200b\u200bthese soil increases. Chestnut soils are very widespread in Kazakhstan, from where the solid band of these soil leaves in Mongolia, and then to East China, occupying most of the territory of Mongolia and the central provinces of China. In Central I. Eastern Siberia. Chestnut soils are found only to the islands. The most eastern area of \u200b\u200bthe spread of chestnut soils - steppes of the South-Eastern Transbaikalia.

The spread of brown desert-steppe soils is more limited - it is predominantly semi-desert areas of Kazakhstan.

In North America, brown and brown soils are located in the central part of the continent, from the east, the border with the Black East Zone, and from the West with the Rockies. In the south, the distribution area of \u200b\u200bthese soils is limited to Mexican plateorem.

The climate of dry and desert steppes is sharply continental, continentality is enhanced by movement from the west to the east (in Eurasia). The average annual temperature varies from 5-9 ° C in the west to 3-4 ° C in the east. Annual precipitation decreases from north to south (in Eurasia) from 300-350 to 200 mm. The sediments are distributed evenly. Evaporability (the conditional value characterizing the maximum possible evaporation in a given area with an unlimited water reserve) significantly exceeds the amount of atmospheric precipitation, therefore the immense water regime is dominated here (the soils are missed at a depth of 10 to 180 cm). Strong winds further drain the soil and contribute to erosion.

In the vegetation of this region, steppe cereals and wormwood prevail, the content of which from the north to the south increases. The vegetation biomass of dry steppes is about 100 c / ha, and its main part (80% or more) is accounted for underground organs of plants. Annual OPED is 40 c / ha.

Soil-forming breeds are lesid loam lines, which occur in the rocks of various composition, age and origin.

Building profile of brown and brown soils:

A - humus horizon. In brown soils, it is a grayish-brown color, saturated with roots of plants, a liner structure and has a power of 15-25 cm. In brown soils, it is brown, a lumpy fragile structure, with a capacity of about 10-15 cm. The content of humus in this horizon from 2 to 5 % in brown soils and about 2% in brown.

B - the transitional horizon of brown-brown color, compacted, at the bottom there are carbonate neoplasms. Power 20-30 cm.

C - soil-forming breed, represented by the Ledsovid Suglink of the yellowish-brown color in brown soils and brownish-fawn in the brown. In the upper part there are carbonate neoplasms. Below 50 cm in brown soils and 1 m in chestnuts there are laggings of plaster.

Changing the number of humus down the profile is gradually, as in the chernozem. The reaction of the soil solution in the upper part of the profile is low-alkaline (pH \u003d 7.5), below the reaction becomes more alkaline.

Among the chestnut soils are distinguished by three subtypes that replacing each other from the north to south:

Dark-chestnuts , With the power of the humus horizon about 25 cm and more, brown with the power of the humus horizon about 20 cm and light-chestnut, with a power of the humus horizon about 15 cm.

The characteristic feature of the soil cover of dry steppes is the extraordinary film, this is due to the redistribution of the forms of the meso and microrelief of heat and especially moisture, and together with it and water-soluble compounds. The lack of moisture is the cause of a very sensitive reaction of vegetation and soil formation even on a weak change in moisture. Zonal automorphic soils (i.e., brown and brown desert-steppe) occupy only 70% of the territory, the rest falls on saline hydromorphic soils (solonges, Solonchaki dr.).

The complexity of using soils with dry steppes for agriculture is due to both a low content of humus and the adverse physical properties of the soil themselves. In agriculture, mainly use dark brown soils in the most moisteable areas and which have a rather high degree of fertility. With proper agricultural engineering and the necessary landing, these soils can give sustainable yields. Since the basis of the cause of fault is the lack of water, the problem of irrigation is becoming special sharpness.

In medical and geographic terms, brown and especially brown soils are overloaded with easily soluble compounds and have an increased content of some scattered chemical elements, first of all, fluorine, it may have negative consequences for a person.

The climate of the Eurasian desert is hot in the summer (the average temperature of July 26-30 ° C) and cold winters (the average temperature of January varies from 0 -16 ° C in the north of the zone to 0 + 16 ° C in the south of the zone). The average annual temperature varies from + 16 ° C in the northern part to + 20 ° C in the southern part of the zone. The number of drop-down precipitation is usually not more than 100-200 mm per year. The distribution of precipitation by month is uneven: the maximum falls on the winter-spring time. Water mode the unscroximal - soil is missed at a depth of about 50 cm.

The vegetable cover of the desert, mainly a Solyankovo-shrub with ephemery plants (annual herbaceous plants, all the development of which takes place in very short term, more often in early spring). In the soils, the deserts have a lot of algae, especially on the taxi (type of desert hydromorphic soils). The vegetation of the desert is vigorously vegetates in the spring with a lush development of ephemers. At dry season, life in the desert freezes. The biomass of semi-staples desert is very small - about 43 c / ha. The small mass of the annual cast (10-20 c / ha) and the energetic activity of microorganisms contribute to the rapid destruction of organic residues (there is no non-comprehensive appearance on the surface) and a small content of humus in gray-brown soils (up to 1%).

Among the soil-forming rocks are predominant with the formal and annular deposition, recycled by the wind.

Serious brown soils are formed on sublime plain areas of relief. The characteristic feature of these soil accumulation of carbonates in the top of the soil profile, which has the form of a surface porous crust.

The structure of the profile of gray-brown soils:

And K is a carbonate horizon, it is a surface crust with characteristic rounded pores that ripped into polygonal elements. Power - 3-6 cm.

And - the weakly pronounced humus horizon of gray-brown color, in the upper part weakly bonded roots, a Book loose, easily flown by the wind. Power 10-15 cm.

B is a transitional compacted horizon of brown color, a prism-shaped-chip structure containing rare and poorly pronounced carbonate formations. Power from 10 to 15 cm.

C - soil-forming breed - loose loess-shaped loam, filled with small crystals of gypsum. At a depth of 1.5 m and below, a peculiar gypsum horizon is often located, presented by the accumulations of vertically arranged needle crystals of plaster. Gypsum horizon power from 10 cm to 2 m.

Characteristic hydromorphic soils deserts are salt marshes , those. Soils containing 1% and more easily soluble salts in the upper horizon. The main mass of salt marsh is common in the desert zone, where they occupy about 10% of the area. In addition to the desert zone, the salt marshes are widely distributed in the semi-desert and steppes zone, they are formed with close grounding of groundwater and payout aqueous mode. Salt-containing soil water reaches the surface of the soil and evaporate, as a result of salts are deposited in the upper horizon of the soil, and its salinization occurs.

The soil salinization can occur in any zone at sufficiently dry conditions and the close arrangement of groundwater, the confirmation of this is self-confirmation in the arid areas of taiga, tundra and the Arctic zones.

Solonchaki vegetation is originally specialized in relation to the conditions of significant salts in the soil.

The use of soil deserts in the national economy is associated with difficulties. Due to the lack of water, agriculture in the desert landscapes wears a selective character, the bulk of the desert is used under distant animal husbandry. At the irrigated areas of serozov, cotton and rice cultivated. Oasis of Central Asia Many centuries are famous for fruit and vegetable crops.

The increased content of some scattered chemical elements (fluorine, strontium, boron) in the soils of individual areas can determine endemic diseases, for example, destruction of teeth as a result of the effects of high fluorine concentrations.

1. Red Grindes and Wet Wet Landscapes subtropical forests

These soils are widespread in the subtropical part of East Asia (China and Japan) and in the south-east of the United States (Florida and neighboring southern States). They are in the Caucasus - on the coast of Black (Adjara) and the Caspian (Lankaran) of the seas.

Climatic conditions wet subtropics Characterized by a large amount of precipitation (1-3 thousand mm per year), soft winter and moderately hot summer. The precipitates are unevenly distributed during the year: in some areas the bulk of precipitation falls in the summer, in others - in the autumn-winter period. Water mode prevails.

The composition of the forests of wet subtropics is varied depending on the floristic area, to which one or another area belongs. The biomass of subtropical forests exceeds 4000 centners / ha, the mass of the podium is about 210 c / ha.

The characteristic type of soils of wet subtropics - the colors, called due to their painting due to the composition of the soil-forming rocks. The main soil-forming breed on which the reds develops, - the thickness of the disked produced products of the weathetic brick-red or orange color. Such a color is due to the presence of firmly connected hydroxides

The structure of the soil profile:

A 0 is a weakly decomposed forest litter, consisting of leafy pods and thin branches. Power - 1-2 cm.

A 1 - humus horizon of gray-brown color with a reddish tint, with a large number of roots, a lining structure and 10-15 cm. The content of humus in this horizon is up to 8%. Down the profile The content of humus is quickly reduced.

B - transitional horizon of brown-red color, red shade is enhanced down. A dense, lumpy structure, in terms of dead roots, clay drums are visible. Power - 50-60 cm.

C - soil-forming red breed with whiten spots, there are clay pellets, there are minor iron orders. In the upper part, film and clay flux are noticeable.

The reds are characterized by an acidic reaction of the entire soil profile (pH \u003d 4.7-4.9).

The yellow-bees are formed on clay shale and clay with poor water permeability, as a result of which in the surface part of the profile of these soils there are developing processes that cause formation in soils of oxide-ferrous nodules.

The soil of wet subtropical forests are poor nitrogen and some ash elements. To increase fertility, organic and mineral fertilizers are needed, first of all, phosphates. The development of soils of wet subtropics is complicated by strong erosion, developing after the information of the forests, therefore, the agricultural use of these soils requires anti-erosion events.

2. Brown soils of landscapes of dry subtropical forests and shrubs

Soils, called brown, formed under dry forests and shrubs, are widespread in southern Europe and in the North-West Africa (Mediterranean area), in southern Africa, the Middle East, in a number of Central Asian areas. Such soils are found in warm and relatively dry areas of the Caucasus, on the southern shower of the Crimea, in the mountains of Tien Shan. In North America, the soils of this type are common in Mexico, they are known in Australia under dry eucalyptus forests.

The climate of these landscapes is characterized by positive average annual temperatures. Winter warm (temperatures above 0 ° C) and wet, summer roast and dry. The annual precipitation is significantly about 600-700 mm, but their distribution is uneven during the year - most of the precipitation falls from November to March, and there are few precipitation in the hot summer months. As a result, the soil formation occurs in the conditions of two periods that replace each other: wet and warm, dry and roast.

Brown soils formed under dry forests of various species composition. In the Mediterranean, for example, these are forests from evergreen oak, laurel, seaside pine, tree juniper, as well as from dry shrubs such as a shiblyak and McWis, from hawthorn, holding a tree, fluffy oak, etc.

Brown Soil Profile Structure:

A 1 is a humus horizon of brown or dark brown color, a lump structure, a power of 20-30 cm. The content of humus in this horizon is 2.0-2.4%. Down the profile, its content gradually decreases.

B is a compacted transition horizon of bright brown color, sometimes with a reddish tint. In this horizon, carbonate neoplasms are often contained, in relatively humid areas they are located at a depth of 1-1.5 m, in arid areas they can already be in the humus horizon.

C - soil-forming breed.

The reaction of soils in the upper part of the profile is close to neutral (pH \u003d 6.3), at the bottom it becomes slightly alkaline.

Soils of subtropical dry forests and shrubs are high-grade and are used for a long time for agriculture, including for viticulture, dilution of olive and fruit trees. Minding forests to expand the areas of the processed lands in combination with the mountainous relief contributed to the erosion of soil. So in many countries of the Mediterranean, the soil cover was destroyed by many areas that once served by the Roman Empire residents are now covered with deserted steppes (Syria, Algeria, etc.).

3. Serozia dry subtropics

In arid landscapes semi-desert subtropical belt Server are formed , they are widely represented in the foothills of the ridges of Central Asia. They are distributed in the north of Africa, in the continental part of the south of North and South America.

The climatic conditions of the serous zone are characterized by warm winter (average monthly temperature of January about -2 ° C) and hot summer (average monthly temperature of July 27-28 ° C). Annual precipitation ranges from 300 mm at low foothills up to 600 mm at the foothills located at an altitude above 500 m above sea level. During the year, the sediments are distributed during the year very unevenly - the main part of them falls in winter and in the spring, in the summer very little falls.

Serous vegetation is defined as subtropical steppes or low-aligned semi-walled. In vegetable cover, cereals predominate, characterized by giant umbrellas. During the spring moisturizing, ephemers and ephemeroids - turbines, tulips, poppies, etc. vegetate, violent.

Soil-forming breeds are predominantly forests.

Seroz's profile structure:

A - the humus horizon of light gray color, noticeably apparently, it is unclear a lifelong structure, with a capacity of 15-20 cm. The amount of humus in this horizon is about 1.5-3%, down the profile The content of humus decreases gradually.

A / B - intermediate horizon between humus and transition horizons. More loose than humus, power - 10-15 cm.

B - the transitional horizon of brownish-fawn color, weakly-skinned, contains carbonate neoplasms. At a depth of 60-90 cm, laughing gypsum begin. To the soil-forming breed passes gradually. Power of about 80 cm.

C - soil-forming breed

The entire profile of serozles is traces of intensive activities of earthquakes - worms, insects, lizards.

Serozia semi-desert subtropical belts border with gray-brown soils of a moderate belt desert and are associated with them gradual transitions. However, typical serosons differ from gray-brown soils with the absence of surface porous crust, less content of carbonates in the upper part of the profile, much greater humus content and lower arrangement of gypsum neoplasms.

In serosms there is a sufficient amount of chemical elements necessary to feed plants, with the exception of nitrogen. The main difficulty in their agricultural use is associated with a lack of water, so irrigation is important for the development of these soil. So, on irrigated serozes in Central Asia, rice and cotton are cultivated. Agriculture without special irrigation is possible mainly in elevated sections of foothills.

Tropical soils occupy more than 1/4 surfaces of the world sushi. The conditions for soil formation in the tropics and high latitudes are sharply different. The most notable distinguishing features of tropical landscapes are climate, vegetable and animal world, but these differences are not limited. Most of the tropical territory (South America, Africa, Peninsula, Industan, Australia) is the remains of the oldest sushi (Gondwana), on which the weathering processes have passed for a long time - starting from the lower Paleozoa, and even with the Precambria. Therefore, some important properties of modern tropical soils are inherited from ancient weathelation products, and individual processes modern soil formation Differently related to the processes of the ancient stages of hypergenesis (weathered).

Traces of the most ancient phase of hypergenesis, the formation of which is widespread in many areas of the ancient sushi, are presented with a powerful weathered bark with a differentiated profile. These ancient bark of tropical territory, as a rule, do not serve as the soil-forming rocks, are usually buried under later formations. In areas of deep faults, cutting into the Cenozoic sections of the ancient sushi and accompanied by powerful volcanic eruptions, these barks are covered with powerful cover of Love. However, on immeasially large Square The surface of the ancient weathering cinema is covered with peculiar coating sediments of red. These red-colored sediments, reducing the huge territory of the tropical sushi, are a completely special hypergenic education, which arose in other conditions and is significantly more time than the ancient weathelation bark.

Red color sediments have a sled-loom composition, their power varies from several decimeters to 10 m or more. These deposits were formed in sufficiently wet conditions, conducive to high geochemical activity of iron. As part of these sediments there is iron oxide, it is he gives deposits a red color.

These red color deposits are the most typical soil-forming tropic rocks, so many tropical soils have a red or close color to it, which is reflected in their names. These colors inherit the soil, the formation of which can occur in various modern bioclimatic conditions. Along with red-color sediments, lake loams, having gray, light yellow sandy alluvial sediments, brown volcanic ashes, etc., can be used as the soil-forming rocks, brown volcanic ashes, etc., so the soils formed in the same bioclimatic conditions are not always the same color.

The most important feature of the tropical belt is a steady high air temperature, so special meaning Acquires the nature of atmospheric moistening. Since evaporation in the tropics is high, then the annual amount of precipitation does not give the ideas about the degree of atmospheric moistening. Even with a significant annual amount of precipitation in tropical soils, throughout the year, a dry period is changed (with the amount of precipitation less than 60 mm per month) and the wet period (with the amount of precipitation more than 100 mm per month). In accordance with moisturizing in soils, there is a change of irregular and flushing regimes.

1. Soil landscapes of rain (constantly wet) rainforest

Constantly wet rainforests are common on large territory in South America, Africa, Madagascar, in Southeast Asia, Indonesia, in the Philippines, in New Guinea and Australia. Under these forests, soils are formed for which different time Different names were offered - red-yellow lathe, ferralliticand etc.

The climate of these forests is hot and wet, the average temperatures of more than 20 ° C. The annual precipitation amount is 1800-2000 mm, although in separate places it reaches 5000-8000 mm. Duration of dry period does not exceed 1

The abundance of heat and moisture determines the largest biomass among the biocenoses - about 5000 c / ha and the mass of the annual patch - 250 c / ha. There is almost no forest litter, since almost all OPEDs are destroyed throughout the year due to the intensive activities of soil animals and microorganisms. Most of the elements released as a result of decomposition are immediately captured by a complex root system. rainforest And again involved in the biological circulation.

As a result of these processes, there is almost no humus accumulation in these soils. The humus horizon of the soil of the gray-colored rainforest, very low (5-7 cm) and contains only a few percent of humus. It is replaced by the transition horizon of A / B (10-20 cm), during which humus hue completely disappears.

The peculiarity of these biocenoses is that almost the entire mass of the chemical elements necessary for the nutrition of plants are contained in the plants themselves and only due to this is not washed away with heavy atmospheric precipitation. When cutting a rainy rainforest, precipitation Very quickly blur the upper thin fertile soil layer and fruitless land remains under the forest.

2. Soils of tropical landscapes of seasonal atmospheric moistening

Within the tropical sushi the largest square It is not constantly wet forests, but a variety of landscapes, atmospheric moisturizing on which unevenly uneven, and temperature conditions change insignificantly (the average monthly temperatures are close to 20 ° C).

With a duration of a dry period from 3 to 6 months a year at the annual amount of precipitation from 900 to 1500 mm, landscapes of seasonally wet bright rainforests and highly harvested savannes are developing.

Light tropical forests are characterized by free arrangement of trees, abundance of light and, as a result of this, lush cover of cereal herbs. High-retard savannahs are various combinations of grassy vegetation with the islands of the forest or separate specimens of trees. Soils that are formed under these landscapes are called red or ferallotic soils of seasonally wet rainforest and highly harvested savannah

Structure of the profile of these soils:

From above there is a humus horizon (a), in the upper part more or less accepted, with a capacity of 10-15 cm, dark gray. The following is the transitional horizon (B) below, during which the gray shade is gradually disappeared and the red color of the soil-forming rock is enhanced. Power of this horizon - 30

These soils are widely used in tropical agriculture. The main problem when using them is a slight destruction of soil under the action of erosion.

With the duration of the dry period from 7 to 10 months a year and the annual amount of precipitation 400-600 mm, xerophytic biocenoses develop, which are a combination of dry wood-shrub thickets and low herbs. Soils, forming under these landscapes, are called red-brown soils dry savannah.

The structure of these soils:

Under the humus horizon A, with a capacity of about 10 cm, a weakly gray shade, a transition horizon in, with a capacity of 25

These soils are widespread in Central and Western regions of Australia, in some areas tropical Africa. For agriculture, they are unsuitable and used mainly under pastures.

With the annual amount of precipitation less than 300 mm, the soils of arid tropical (semi-desert and deserted) landscapes are formed , having common features With gray-brown soils and serozia. They have a low-power and carbonate weakly differentiated profile. Since the red-forming rocks in many areas are red-colored products [neogenic] weathered, these soils have a reddish color.

Soil-forming rocks on such islands serve snow-white coral sands and reef limestone. Vegetation is represented by thickets of shrubs and forests of coconut palm with intermittent cover from low cereals. Here are the most common atoll humus-carbonate sandy soils with a low-power humus horizon (5-10 cm), characterized by the content of humus 1-2% and pH about 7.5.

Often an important factor for soiling on the islands is Ornithofauna. The colonies of birds are laying huge amounts of litter, which enriches the soil with organic matter and contributes to the emergence of special wood vegetation, thickets of high herbs and ferns. In the soil profile, a powerful peat-humus horizon with an acidic reaction is formed. Such soils are called atoll melano-humus-carbonate.

Gumus-carbonate soils are an important natural resource of numerous island states of the Pacific and Indian Oceans, being the main plantation for coconut palm.

One of the distinguishing features of the structure of mountain soil is the low-capacity genetic horizons and the entire soil profile. The power of the mountain soil profile may be 10 or more times less than the power of the profile of similar flat soil, while maintaining the structure of the flat soil profile and its features.

Mountain areas are characterized by vertical zonality (or explanation) soil cover, under which the natural change of alone soils is understood as it is raised from the foot to the vertices of high mountains. This phenomenon is due to a natural change in hydrothermal conditions and composition of vegetation with a height. The lower belt of the mountain soil belongs to the natural zone, on the square of which are mountains. For example, if the mountain system is located in the desert zone, gray-brown desert soils will be formed on its lower belt, but with a lifting up the slope, they will alternately replace the mountain-chestnut, mining and chernozem, mining and mountain-meadow soils . However, under the influence of local bioclimatic features, some natural zones may fall out of the structure of the vertical zonality of soil cover. Inversion of soil zones may be observed, when one zone turns out to be higher than it should be done with horizontal.

Natalia Novoselova