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Part 1. PROPERTIES, CLASSIFICATION, DISTRIBUTION OF SOILS

MORPHOLOGICAL PROPERTIES OF SOIL

SOIL FIELD INVESTIGATION TECHNIQUE

In the field, soils are studied and identified and named according to their external, so-called morphological characteristics, which reflect the internal processes taking place in soils, their origin (genesis) and development history.

N. M. Sibirtsev believed that based on morphological (external) characteristics it is possible define soil in the same way that we identify a mineral, a plant or an animal. Therefore, in field conditions it is especially important to correctly describe soil, note all its features.

To describe soils, study their morphological characteristics, establish boundaries between different soils, and take samples for analysis, special pits are laid, which are called soil sections. They come in three types; full (main) cuts, half holes and digging.

First of all, it is necessary to carefully inspect terrain, determine the nature of the relief and vegetation for the correct choice of the location of the soil section.

Incision required pawn in the most characteristic place of the surveyed territory. Soil sections should not laid near roads, next to ditches, on microrelief elements atypical for a given territory (depressions, hummocks).

In a selected area of ​​the terrain, they dig a soil section so that its three walls are sheer, and the fourth was descending steps(Fig. 1).

Rice. 1. Soil section

The anterior, facial, wall of the incision intended for description should be facing the sun.

When digging a pit, the soil should only be thrown away on the sides and in no case on the front wall, which can lead to its contamination, destruction of the upper horizons, changes in their thickness, etc.

Full or main cuts laid to such a depth as to expose the upper horizons of the unchanged parent rock. Typically this depth ranges from 1.5 to 5 m depending on the thickness of the soil and the objectives of the study. Such sections serve for a special detailed study of the morphological properties of soils and for taking samples for physical and chemical analyses.

Half-pits, or control cuts, are laid at a shallower depth - from 75 to 125 cm (before the beginning of the parent rock). They serve to study the thickness of humus horizons, the depth of boiling from hydrochloric acid and the occurrence of salts, the degree of leaching, podzolization, salinity and other characteristics, as well as to determine the area of ​​distribution of soils characterized by complete sections. If, when describing the half-pit, new signs were discovered that were not previously noted, then a full incision must be made at this place.

Digs, or small superficial cuts, less than 75 cm deep, serve primarily to determine the boundaries of soil groups identified by the main sections and half-pits. Usually they are laid in places where one soil is expected to change from another.

Descriptions of soil sections, hollows and excavations are entered in diary, in which, in addition, information about the relief, vegetation, groundwater, and the results of field studies of the physical, chemical and other properties of the soil should be recorded. Approximate form The field soil diary is given below. You need to pay special attention to these signs and study them most carefully.

Rice. 2. Sample of a diary for describing a soil section:

Month ________ 1. Section No. _____________________ 2. Region _____________________________________ District _____________________________________ 3. Village council, collective farm, state farm ________________________________________________________________ 4. Point _________________________________________________________________________________ 5. General relief ________________________________________________________________________________ 6. Microrelief ___________________________________________________________________________ 7. Position of the section relative to the relief and exposure _______________________________________ 8. Vegetation cover _____________________________________________________________________ 9. The site and its cultural state __________________________________________________________ 10. Signs of swampiness, salinity and others characteristics _____________________ 11. Depth and nature of boiling from HCl _______________________________________________________ 12. Level of soil and groundwater __________________________________________________________ 13. Mother and underlying rock _______________________________________________________ 14. Soil name ________________________________________________________________________________ The main morphological characteristics by which the soil in the field is determined: 1) structure of the soil profile, 2) color (color) of the soil, 3) degree of moisture (as well as the level of groundwater or high water), 4) mechanical composition, 5) structure, 6) composition, 7) new formations.

Sample form for describing a soil section:

• Part I. Properties, classification, distribution of soils
  • Definition of the concept “soil”, its place in nature and life
  • Morphological properties of soils
    • Technique field research soils
• Part 2. Soil key
• Part 3. Systematic descriptions of soils

On the website of the ecological center "Ecosystem" you can also get acquainted with abstracts and articles on soil science.

Determination of soil (type, mechanical composition, soil-forming rock, groundwater level) ____

________________________________

The description of morphological characteristics and the determination of soils are carried out according to the scheme, starting sequentially with the forest litter and ending with the parent rock. Various connected layers (genetic horizons) of soils are characterized by external (morphological) features that arise in specific conditions under the influence of soil formation processes. The main characteristics of soils are: the structure of the soil profile (thickness, shape and nature of transitions between horizons, etc.), color, granulometric (mechanical) composition, structure, moisture, density, presence of neoplasms, zoogenic elements and inclusions. These characteristics are indicated for each horizon of the soil profile.

Structure of the soil profile. The following main soil horizons are distinguished:

A 0 (0)- forest floor, the ground layer formed in a forest from vegetation decay of varying degrees of decomposition. Depending on the degree of decomposition in the litter composition, subhorizons are distinguished: A I 0 (A L) - formed by undecomposed plant remains (leaves, branches, fruits, cones, etc.); A II 0 (A F) - the fermentation (decomposition) layer consists of slightly decomposed plant residues that retain a distinct tissue structure; A III 0 (A h) - the humification layer consists of highly crushed, decomposed litter, the tissue structure of which is poorly distinguishable.

Depending on the species composition of the tree stand, the rate of decomposition, the structure and color of the formed litter and humus layer, soft humus (mull), transitional humus (moder) and coarse humus (mor) are distinguished.

Soft humus it is made up of soft, loose litter that decomposes within 1 - 2 years, so it is quite thin (1-2 cm), consists of small organic substances that form a homogeneous mass of brown (almost black) color. It is formed in forest stands consisting of linden, maple, ash, birch, aspen, hazel, etc.

Transitional humus formed from less soft and loose litter, decomposing within 2-5 years (usually 2-5 cm thick), consists of significantly, but not completely decomposed crushed plant residues of a brownish-brown color. Formed in oak and coniferous-deciduous forest stands.

Rough humus It is obtained from hard, dense litter that decomposes over more than 5 years, often more than 5 cm thick, and consists of partially decomposed plant debris that retains its tissue structure. Formed in coniferous stands.

A D - turf. The upper horizon is densely penetrated by intertwined plant roots, which make up more than 5% of the horizon volume. It is usually absent in forest communities, as it forms mainly in meadows.

A 1 (A) - humus horizon(humus-accumulative). As a rule, it is the darkest colored and accumulates humified organic matter associated with the mineral part of the soil. With a high content (more than 30%) of organic residues, this horizon is sometimes called humus.

A p - arable horizon, is formed as a result of plowing from various soil horizons (for example, under forest plantations).

T - peat horizon(organic matter content more than 70%), characteristic of peat soils. Depending on the degree of decomposition, color and composition, it is divided into subhorizons T 1, T 2 etc.). The degree of peat decomposition is determined by diagnostic characteristics (Appendix 11). Based on the predominance of remains of various plant groups in its composition, they are distinguished woody(pine, birch, alder, etc.), herbaceous(sedge, reed, shift, horsetail, etc.) and mossy(sphagnum, hypnum, etc.) peats, as well as their various combinations. For diagnosis, special determinants are used. The presence of peat in other horizons is indicated by the letter “t” (for example, A T).

Horizons A 0 - T classified as organogenic.

A 2 (E) - eluvial podzolic horizon, usually the lightest colored (from whitish to fawn) due to the leaching of humus and other compounds into the underlying horizons.

B - illuvial horizon, characterized by a compacted build and brown, pale-brown or reddish-brown color. It contains the accumulation of substances washed out from the overlying horizons. Based on the nature of the accumulated substances, the horizon can be divided into: In t - illuvial-clayey (with clay accumulation); In h - illuvial-humus; In k - illuvial-carbonate, In f - Illuvial-ferruginous, etc. Subhorizons are often noticeable in the composition of illuvial horizons (B 1, B 2, B 3).

G - gley horizon, usually bluish, bluish-gray in color, characteristic of soils with constant or prolonged excess moisture. The presence of signs of gleying in other horizons is indicated by the letter “g” (for example, B g, A 2 g etc.). If gleyization is mild, the letter “g” is enclosed in brackets.

C - maternal(soil-forming) rock (the surface layer of rocks from which soils were formed). On the territory of Belarus, soils develop on Quaternary (anthropogenic) deposits, the origin of which is associated primarily with the activity of glaciations. The predominant soil-forming rocks are moraine (actually glacial), fluvioglacial (fluvio-glacial), ancient alluvial (glacio-alluvial) and limnoglacial (lacustrine-glacial).

Among the source rocks not associated with the activity of ancient glaciations, the most common in Belarus are swamp (peaty) and alluvial (floodplain) deposits.

Quite often, some of the listed horizons may be weakly expressed or have signs of adjacent horizons. In this case, transitional horizons are identified, for which double designations are used (A 1 A 2, A 2 B etc.). When describing the profiles of floodplain (alluvial) soils, individual layers of alluvium are also noted in the composition of the horizons (for example, Al 1 A 1, Al 1 G etc.). When describing various horizons, the following symbols may also appear: “d” - degraded, “n” - disturbed, “i” - artificial, “os” - drained, “e” - eroded, etc.

The composition, sequence of occurrence and expression of horizons and subhorizons when describing soil profiles can be presented in the form of formulas that differ for different types of soils. The profile of soddy-podzolic soils, for example, can be expressed by the formula A 0 – A 1 A 2 – A 2 B 1 - B 1 - BC (g) - C (g).

In addition to indicating the thickness of the horizons, a description is given nature of the transition horizons and the shape of the boundaries between them.

There is a transition between horizons harsh(the border is clear, can be distinguished within 1 cm), clear(the border is quite clear, can be distinguished with uncertainty within 1-3 cm), noticeable(the border is unclear, traced with uncertainty within 3-5 cm) and gradual(the boundary is unclear, can be traced with an uncertainty of more than 5 cm). If it is impossible to draw a clear boundary between the horizons and it lies within a layer, then it is identified as a transition horizon.

Soil color. The nature of the color is one of the most important morphological characteristics of the soil. The different colors of the soil are caused by the content of organic, organomineral (dark gray, gray and other colors) and mineral compounds, as well as their combinations. For example, reddish, orange, brown and rusty are usually caused by trivalent and hydroxide compounds of iron and manganese; whitish - silica, carbonates, aluminum oxide (A1 2 O 3), kaolinite; gray, greenish and bluish - divalent iron compounds.

When describing the color of the horizon, first of all, note its main color and color details: uniform(homogeneous, i.e. equally colored), uneven(heterogeneous), with stripes, spots (area more than 1 cm2) and lubricants(blurry spots close in color to the background color of the horizon), and also often use shades of colors, and the dominant color in the name is placed last(dark gray, yellow-brown, etc.). The color of soils is influenced by its moisture content, structural state, as well as the nature of lighting and individual perception of color.

To determine frequently occurring soil colors, the color triangle according to S.A. is sometimes used. Zakharov (1931), in which, however, there are no colors characteristic of gley soils (bluish, greenish, gray). To more accurately determine the color, shades of flowers and their names, there is a special color scale.

Granulometric (mechanical) composition. The soil consists of elementary granules (particles) of various sizes, the totality of which determines its granulometric composition. Particles similar in size are combined into groups (fractions). For field classification, all particles from 0.01 to 1.0 mm are conventionally combined into physical sand fraction, and less than 0.01 mm - in physical clay fraction. Based on the ratio of granules of these two fractions (fine earth) in the soil, several classes of soils are distinguished according to their granulometric composition: clays, loams (heavy, medium, light), sandy loams (loose and cohesive) and sands (loose and cohesive). Particles larger than 1 mm are called soil skeleton, which consists of rock fragments (crushed stone, pebbles, boulders, etc.). In field conditions, the mechanical composition of the soil (fine soil) is determined visually using one or more methods: “mirror”, testing with a knife, rolling a ball, cord, etc. (Appendices 12 and 13). More accurately, the granulometric composition of soils is determined in laboratory conditions.

Soil structure. Under the influence of external conditions, soil particles are usually combined into lumps. The set of such units (aggregates) into which the soil breaks up without significant mechanical impact on it is called structure. In field conditions, soil structure is determined by genetic horizons. To do this, having cut out a small sample of soil from the horizon, throw it on the blade of a shovel 1-2 times, as a result of which the soil breaks up into structural units.

Depending on the shape of the aggregates (the ratio of height and width), three main types of soil structure are distinguished: cuboid, prism-shaped And thyroid, and According to size and shape, types of structures are divided into genera and species (Fig. 2.15).

Types of soil structures are often associated with various soil formation processes and are confined to certain profile horizons: prismatic - with an illuvial process - to illuvial horizons; plate-shaped - with eluvial process - to podzolic; cuboid - with humus formation - to humus. Soil horizons can be formed by aggregates of mixed structure: granular-angular, lumpy-prismatic, etc. If the horizon consists of loose sand of various granulometric compositions, then it is designated as structureless.

Soil moisture.

There are several gradations of soil moisture:

1) if the soil is dusty and moisture is not felt when compressed, it is described as dry;

2) slightly cools the hand and smears weakly - fresh;

3) when compressed, lumps form and the hand noticeably feels moisture - wet;

4) water moisturizes the hand and sticks to it, but does not yet ooze between the fingers - raw;

5) when squeezed between the fingers, water oozes out along with the soil mass (water also protrudes from the soil horizon) - wet. Soil moisture changes in different years and seasons depending on the level of groundwater, the amount of precipitation, the time of its last precipitation, etc.

Horizon density. According to density, soil horizons are loose(it easily crumbles when touched, a knife or shovel goes into the horizon almost effortlessly), weakly compacted(a knife or shovel forcefully enters the soil along the entire length of the blade), highly compacted(only the tip of a shovel or knife blade enters the soil) and dense(a knife or shovel only scratches the surface). The density of the horizon depends on many factors (mechanical composition, structure, soil moisture, etc.).

Neoplasms. New formations (excretions) include noticeable accumulations of various substances that differ morphologically (color, shape, density, etc.) and chemically from the rest of the prevailing soil mass of the horizon. New formations (as opposed to, for example, inclusions) arise as a result of soil-forming processes and are important diagnostic features of soils in the form of deposits, nodules and interlayers.

After studying and describing the soil section, the full name of the soil type is given. With a more detailed determination and morphological-genetic description of soils in its various horizons, qualitative chemical reactions are carried out to determine the presence of carbonates, chlorides, sulfates, ferrous iron and determine the pH value. If necessary, soil samples weighing 0.5-1 kg are separately taken from the middle of each horizon and subhorizon (starting from the bottom), which are provided with a label, wrapped in paper and placed in special bags.

After completing the description of the PP and checking by the teacher that the work was done correctly, the soil section is buried. In this case, the soil of the lower horizons is first placed in the hole, and the soil of the humus horizon is placed on top.

Based on all the information received about the structure of the tree stand, undergrowth, undergrowth, living ground cover, soil-climatic and historical conditions for the development of the phytocenosis under study, the type of forest and forest association at the PP are finally determined.

Soil cuts, depending on their purpose, are divided into main (deep), half-cuts (half-pits) and trenches. The main section is established to identify the soil type and should cover the entire soil thickness, including the top of the parent rock horizon. Its depth is determined by the depth of penetration of the soil-forming process and usually ranges from 150 to 300 cm. The main sections are laid on all new relief elements, when vegetation and parent rocks change. Half-sections serve to establish the subtypes and varieties of soils in the study area and to determine the boundaries of the distribution of various soils. The depth of the half-cuts is 75-100 cm. If, when studying the half-cut, a new type of soil or a change in the parent rock is revealed, the half-cut is deepened to a full cut. Digging to a depth of 25-75 cm is done to establish the boundaries of the distribution of individual types, subtypes and varieties of soils. The average ratio between the main cuts, half-pits and trenches is 1:4:5.

The crucial point is the choice of the location of the incision. The section should be laid under conditions typical for the study area. You cannot lay a cut near roads, ditches, in the corners of crop rotation fields, along the edge of agricultural land (pasture, pasture, meadow), on a hillock or in a depression that is not typical for the entire site. Before laying a cut, carefully study the area to characterize which the cut is laid. If the area under study is a plain, the section is laid in the center of the plain. If a slope is being examined, a full cut is made in the middle part of the slope and half-pits in the upper and lower parts. Often, within one relief element, microrelief is clearly expressed, which can be especially often observed in flat, flat areas, and the microrelief here is represented by a complex of barely noticeable microhighs (hillocks) and microlows (saucer-shaped depressions). In this case, two cuts are laid: one at a micro-high, the second at a micro-low.

Cutting technique. For the cut, mark out a rectangle 120-150 cm long and 60-80 cm wide. The short side of the cut serves as the front side on which the soil is described. This side should be better lit, i.e. should be facing the sun. This cut wall, as well as its two sides, are made completely vertical. On the fourth side, steps are made to descend into the cut. When digging, the soil is thrown out to the left and right of the front wall. The mass of the upper humus horizon is thrown onto one side, and the mass of deeper horizons onto the other. The front side of the cut must not be covered with soil or trampled. After finishing the work, the cut is buried, and the mass of deep horizons is laid down, and the mass of the humus horizon is placed on top.

After excavating a section, its location is plotted as accurately as possible on a topographical basis. The main cuts are indicated by crosses in circles, half-pits - by circles, digging holes - by dots with the obligatory indication of the number. The diary contains sequential numbering of all types of cuts. To link a cut, i.e. To accurately plot its location on a topographical basis, first of all, they navigate the area on a map using a compass. The map is oriented along the compass so that the northern end of the compass needle coincides with the “N” direction of the arrow on the map. Then, taking the compass direction for the cut from any clearly visible landmark (road intersection, corner of the crop rotation field, buildings), determine the distance between them and use a measuring ruler to plot this distance in the appropriate direction. The distance is determined by eye - in steps, having previously set the price of the step (its value in centimeters). You can use the serif method. An arbitrary point is placed on a small sheet of wax and lines are drawn from it through a scale ruler to two landmarks. The wax is then placed on the topographic base so that each of these directions passes through the corresponding landmark sign. The point where the directions intersect is the location point of the cut; it is cut from the wax to the card.

On the map and in the field diary, write the section number and describe it. The serial number of the cut and its location are noted in the diary; accurately indicate the element of relief and microrelief on which the section is located (for example, a plain, a saucer-shaped depression or the middle part of a gentle slope); describe in detail the vegetation (its composition, density, height and condition), as well as the type of agricultural land; describe the parent and underlying rocks, indicating the mechanical composition, the presence of boulders, carbonate crushed stone, and easily soluble salts. The level of soil and groundwater, its quality and the nature of swamping (gleyization) - surface or groundwater - are noted. The degree of soil erosion (washed away) is also noted, and on arable land the nature of its surface (evenness, blockiness, fissuring, presence of crust) and the degree of rockiness are described. If stones (boulders) make up less than 10% of the surface of the arable land, the stoniness is considered weak, if 10-20% is considered medium, and if more than 20% is considered strong.

Draw a profile of the area and indicate the location of the cut with a cross. If the section is laid on a slope, you need to indicate the exposure and steepness of the slope, measuring it in degrees. A slope is considered very gentle with a steepness of less than 1°, gentle - 1-3°, sloping - 3-5°, strongly sloping - 5-10°, steep - 10-20°, very steep - 20-45°, steep - more than 45 °.

The front side of the cut is prepared with a knife or a small spatula in such a way as to obtain its natural fracture. Based on the nature of color, neoplasms, build and other morphological characteristics, genetic horizons are distinguished, and the boundaries between them are drawn with a knife. Then a fabric meter is strengthened along the wall of the cut so that its zero division coincides with the upper level of the soil, and the thickness of each horizon and the depth of the entire profile are measured. In the diary, they sketch the profile with colored pencils, show the depth of penetration and the nature of development of the root system, note new formations, after which boiling and gleying are examined.

The test for carbonates is carried out as follows. Throughout the entire depth, every 10-20 cm, take small pieces of soil with a knife and moisten each with a few drops of a 5% HCl solution, observing the release of CO 2 bubbles. If there is no boiling visible to the eye, you should check for boiling by ear, since with a low carbonate content, the soil only crackles under the influence of acid. Having established the boiling depth of the sample with an accuracy of 10-20 cm, it is clarified by taking samples every 2-3 cm upward from the initially found depth. To determine gleying, samples with red blood salt are made on pieces of soil removed from the cut. Blue discoloration indicates the presence of ferrous forms of iron. The depths of boiling and gleying are noted in the field diary. Then they begin a morphological description of each horizon, noting its color, humidity, mechanical composition, the nature of the distribution of the root system, structure, composition (density, porosity and fracturing), new formations, inclusions, the nature of the transition of one horizon to another. The morphological description must be done very carefully and completely. The profile can be sketched using strokes of moist soil from the corresponding genetic horizons. After the morphological description, the type, subtype and variety of soil are determined and its full name is noted in the diary.



for the Republican rally of young ecologists in the “Young Soil Scientist” competition

SOIL STUDY

What do soil scientists study?

Soil science, despite the importance of soil in our lives, was recognized among the natural sciences only at the end of the 19th century as independent section natural sciences. Through the works of the great Russian researcher Vasily Vasilyevich Dokuchaev, it was shown that this is another shell of the earth’s surface, separate from the atmosphere, hydrosphere and lithosphere.

Fertile soil is a complex natural system consisting of soil horizons formed as a result of the transformation of the surface layers of the lithosphere under the influence of water, air and living organisms.

Based on his studies of chernozem, Dokuchaev defined soils as surface-lying mineral-organic formations that have their own structure, “are constantly the result of the mutual activity of the following agents: living and obsolete organisms (both plants and animals), parent rock, climate, terrain and time factors."

Soil is formed from rocks exposed on the surface of the earth under the influence of various factors. Under the influence of wind, atmospheric moisture, due to climate changes and temperature fluctuations, rocks, such as granite, gradually crack. Microorganisms appear on them, feeding mainly on the carbon and nitrogen of the atmosphere and the mineral compounds that they receive from the rock. Microorganisms destroy it with their secretions, and chemical composition the rock gradually changes. Then lichens and mosses settle here. Animals and higher plants finally destroy the rock, turning its top layer into soil.

What do soils look like? If you arm yourself with a shovel, go beyond settlement and dig a hole in a forest or meadow (hereinafter referred to as a soil profile) (Fig. 1), then you can find a series of layers (soil horizons) differing from each other in color, density, moisture and other characteristics.

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Rice. 2 - Profiles of tundra, podzolic and soddy-podzolic soil.

Soil horizons are formed simultaneously, as a result of the combined action of the above soil formation factors, and this is their significant difference from rocks.

Throughout the 20th century, comprehensive studies of the soil cover of the Earth's land were carried out in order to clarify the basic patterns of origin, functioning, geographical distribution, evolution of soils and soil cover. Huge was received scientific material, revealing the differences between soils and other environments. Similar research has been and continues to be actively carried out in our country. Currently, almost the entire territory of Russia is characterized in terms of soil cover. The main soil types common in certain regions are known (Fig. 3)

Land use" href="/text/category/zemlepolmzzovanie/" rel="bookmark">land use. If groundwater is found during the laying of the section, then it is necessary to note its depth. Then you need to describe the soil profile in detail, progressively from top to bottom, noting the specific features of the identified horizons. If possible, you should make sketches and photographs of the profile exposed by the section.

Methodology for describing soil sections

On the front (front) wall of a soil section illuminated by the sun, soil horizons can be easily identified, replacing each other in the vertical direction and differing in color, structure, mechanical composition, humidity and other signs. General form soil with all soil horizons is called soil structure. The totality of genetic horizons forms the genetic profile of the soil (Fig. 2; Table No. 1). The following genetic soil horizon symbols are currently used:

Table No. 1

Genetic soil horizons

Horizon	Description
Horizon O	The uppermost part of the soil profile is forest litter or steppe felt, which is plant litter at various stages of decomposition - from fresh to completely decomposed.
Horizon A	humus, the darkest colored in the soil profile, in which organic matter accumulates in the form of humus, closely associated with the mineral part of the soil. The color of this horizon varies from black, brown, brown to light gray, which is determined by the composition and amount of humus.
Horizon E	Podzolic or solodized, eluvial, formed under the influence of acidic or alkaline destruction of the mineral part. This is a highly clarified, structureless or layered loose horizon, depleted in humus and other compounds, as well as silt particles due to their leaching into the underlying layers and relatively enriched in residual silica.
Horizon B	located under the eluvial horizon E, has an illuvial character. This is a brown, ocher-brown, reddish-brown, compacted and weighted, well-structured horizon, characterized by the accumulation of clay, oxides of iron, aluminum and other colloidal substances due to their leaching from the overlying horizons. In soils where there are no significant movements of substances in the soil column, horizon B is a transition layer to the soil-forming rock, characterized by a gradual weakening of the processes of humus accumulation and decomposition of primary minerals and can be divided into B1 - a horizon with a predominance of humus color, B2 - a weaker horizon, uneven humus color, B3 - horizon of the end of humus streaks.
Horizon VK	The horizon of maximum carbonate accumulation is usually located in the middle and lower part of the profile and is characterized by visible secondary deposits of carbonates in the form of plaques, veins, pseudomycelium, white-eyes, and rare nodules.
Horizon G	Gley, characteristic of soils with constant excess moisture, which causes restoration processes in the soil and gives the horizon character traits- bluish, grayish-blue or dirty green color, the presence of rusty and ocher spots, unity, viscosity, etc.
Horizon C	The parent (soil-forming) rock from which a given soil was formed, not affected by specific soil formation processes (humus accumulation, eluviation, etc.).
Horizon D	The underlying rock lies below the parent (soil-forming) rock and differs from it in its properties (mainly in lithology).

In addition to the listed horizons, a whole series of independent and transitional horizons are distinguished, but more details about them can be found in literary sources.

Method of determinationbasic morphological properties of soils

When describing the morphological characteristics of horizons, soil color, moisture, granulometric composition, structure, soil composition, new formations, and inclusions are indicated.

Soil coloring - one of the main external signs. The color of the soil allows us to judge the presence and quantity of substances in the soil mass: humus (humus) substances color the soil in dark (gray and brown) tones; in ocher-yellow, orange and red tones - oxides of iron and manganese; The formation of white spots, grease and "mold" is caused by the presence of lime in the soil.

Soil granulometric composition – the most important soil characteristic (Fig. 4). Almost all properties of the soil (water-physical), physico-chemical, air, thermal, redox, absorption capacity, accumulation of humus, ash elements and nitrogen) and, consequently, its fertility depend on it. Tillage conditions, timing of field work, mineral standards, and organic fertilizers and doses of lime, drainage parameters, selection of crops, etc.

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Rice. 5. Determination of soil type.

Table No. 2

Determination of soil type by the nature of the formation of the cord

Soil type	Character of cord formation
The soil is sandy	The ball does not form. The sample completely disintegrates in the hand.
The soil is sandy loam	The resulting ball has a rough surface. When you try to roll it into a cord, it immediately falls apart into pieces.
The soil is light loamy	When you try to lift it from your palm, the cord breaks into pieces.
Medium loamy	When the cord is rolled into a ring, it breaks.
The soil is heavy loamy	When you roll the cord into a ring, it cracks
The soil is clayey	When the cord is rolled into a ring, no cracks are formed.

Soil structure - This is the ability to disintegrate into individual particles. To determine the structure, it is necessary to cut out a sample with a shovel, toss it 1-2 times on the shovel and examine the shape of the structural units into which the soil sample has broken up. Based on the shape of the aggregates, three types of soil structure are distinguished (cuboid, plate-shaped, and prism-shaped), which in turn are divided into several genera taking into account the shape and size of the lumps (Fig. 4).

Water resistance of structural agents (i.e. the ability to resist the erosive action of water). It is enough to place several structural agents in a glass of water. If, with light shaking, they quickly collapse, this indicates their fragility. And if they retain their shape, then, consequently, the soil has a water-resistant structure.

Density (addition) – the nature of the adhesion of soil particles to each other and the degree of their porosity – is closely dependent on the granulometric composition, humus content, abundance of roots, structural state, humidity and varies greatly across horizons (Table 3).

Table No. 3

Determining the type of soil composition

Types of addition	Characteristic
Friable	A shovel or knife is easily immersed in the soil, the soil effortlessly crumbles into individual aggregates
	The knife penetrates with little effort to a depth of 3-5 cm, the soil is easily broken by hand
	With great effort, the knife enters to a depth of 3-5 cm.
Very dense	With a strong impact, a shovel or knife penetrates the soil to a depth of no more than 1 cm.

Humidity – an important morphological feature: it affects the color, structure, and density of soils. In field conditions, you can determine five degrees of soil moisture by taking the soil in your hand and squeezing it (Table No. 4).

Table No. 4

Determination of soil moisture level

Humidity level	Characteristic
	The soil is dusty and does not cool your hand.
	The soil is not dusty, cools your hand, and becomes a little lighter when it dries.
	The soil sticks together into a lump when you squeeze your hand, when it dries it becomes lighter and retains its shape, a wet mark remains on your hand, the filter paper becomes wet when applied to a lump of soil.
	When squeezed in the hand, the soil sticks to it and wets the hand, but water does not ooze over the fingers.
	The soil, when squeezed in the hand, greatly wets the hand, water does not ooze over the fingers or water oozes from the horizon.

All results obtained during field research are recorded in a diary to describe the soil section (Appendix)

In addition to morphological properties, soil horizons have a number of chemical and physical properties(acidity, fertility, etc.), many of which are studied in laboratory conditions. To do this, after completing the morphological description of the soil profile, samples are taken from the selected horizons for analysis. Usually selected gr. soil. The selection is carried out in soil bags or craft bags, must be labeled (information about the horizon is applied to a sheet of paper and placed along with the sample) and delivered to the laboratory. If the delivery time to the laboratory is long, then the samples are dried in a dry, ventilated area.

Soil fauna research

The living part of the soil consists of soil microorganisms (bacteria, fungi, algae, etc.), representatives of invertebrates (protozoa, worms, mollusks, insects and their larvae), and digging vertebrates. Among this soil world of animals, we can distinguish those forms that spend their entire lives in the ground, never appearing on its surface (for example, small oligochaete worms, nematodes), and those that we can find outside the soil (most animals). The latter are associated both with terrestrial fauna, in particular, with grass, shrubs and trees, and partly with water (some aquatic beetles, like swimming beetles and water lovers, pupate in the ground; some representatives of these families bury themselves in the ground for the winter, and do the same and newts). The population of the soil is undoubtedly a feature of adaptation to an underground lifestyle (such as the digging forelimbs of a mole, etc.). But in many animals we will not find any peculiarities in this regard (various caterpillars, many beetle larvae, such as ground beetles, etc.). Living in the soil, many animals have a significant impact on their environment. Firstly, they can influence the mechanical structure of the soil, loosening and processing it, and secondly, thanks to their vital activity, they change it chemically. In addition, many enter into relationships with the underground parts of plants, which serve as food for them (beetleworm larvae) or settle near the roots, like some ants. Finally, a significant part of the animals living in the soil lead a predatory lifestyle, attacking various representatives of the same soil fauna (moles, various predatory larvae, ground beetles, etc.).

Methodologysoil fauna research

Method of manual disassembly of soil samples (Gilyarov, 1975). This is a direct method of counting, allowing the researcher to obtain figures showing the number of objects counted per unit area of ​​soil surface, or per unit volume of soil. At the same time, the taxonomic composition of the mesofauna is being studied.

We can find animals in the soil almost everywhere, but their distribution is very uneven. The following methods can be used to obtain material:

1. Digging more or less deep holes.

2. Loosening or digging up the surface layers of soil with a shovel.

3. Digging up individual plants to find insects on the roots.

4. Inspection of the soil surface to detect nests of animals settling in the soil.

5. Inspection of layers of earth in soil sections, slopes near river banks, in ravines, in artificial structures (pits, ditches, etc.).

The sampling process is as follows. First, mark the sample area in the area under study by driving pegs into the corners of the measured square and pulling a string between them. Then, from the boundaries of the measured area, they are raked into different sides litter or litter (if samples are taken in the forest) or dry loose soil of the surface layer (in fallow). An oilcloth is laid out next to the sample on one or both sides, on which the soil selected from the sample is then placed. First, litter and other plant remains are removed from the sample area onto an oilcloth by hand, which are carefully sorted by hand, taking into account and collecting all the animals found, and the grass is plucked out, which facilitates further disassembly from the top layer of soil. Invertebrates encountered on the soil surface are recorded and recorded separately from those encountered in the soil itself. Then (after removing the disassembled plant residues) they begin to dig out the soil from the sample area with a shovel. Small portions of soil thrown onto an oilcloth (or other bedding) laid out next to the sample are carefully sorted out by hand, and more large clods you have to break it, and the plexus of roots and turf have to be torn apart. All the soil from the dismantled layer is ground, portion by portion, by weight between the palms, carefully monitoring all the soil that falls onto the oilcloth and collecting falling animals that are easily detected.

Animals are collected separately from each sample and layer. 4% formalin can be used as a fixative for worms; other groups of animals can be fixed in 700 alcohol. All animals found during excavations are immediately recorded in the field in a diary with the accuracy of determination that is available to the researcher. The diary provides a detailed description of the site and sampling location.

If it is necessary to make a quantitative record of the fauna, then you should prepare the “Soil Fauna” sheets and enter the relevant data into them during excavations (Appendix).

Application

Diary form for describing a soil section

Month 200

1. R. No. __________________

2. Region _____________________________ District __________________________

3. Point ______________________________________________________________

_______________________________________________________________________

4. General relief ____________________________________________________________

_______________________________________________________________________

5. Microrelief __________________________________________________________

_______________________________________________________________________

6. Position of the section relative to the relief and exposure _____________________

_______________________________________________________________________

7. Vegetation cover ___________________________________________________

_______________________________________________________________________

8. Land and its cultural condition _____________________________________________

9. Signs of swampiness, salinity and other characteristic features _______________________________________________________________________

_______________________________________________________________________

10. Depth and nature of boiling from HCl (weak/strong) _______________________

_______________________________________________________________________

11. Level of soil and groundwater ________________________________________________

12. Mother and underlying rock ___________________________________

_______________________________________________________________________

13. Soil name _____________________________________________________

Drawing diagram soil section	Horizon and power in cm	Description of the horizon

Application

Soil fauna

Date ______________________ Time ______________________________

Place __________________________________________________________

Nature of the area ______________________________________________

Vegetation type ______________________________________________

Size of the pit ___________________________________________________

Animals found	1st layer 0-10 cm	2nd layer 10-20 cm	3rd layer 20-30 cm	4th layer 30-40 cm	Notes

Below is a list of the most commonly found animals in the soil and available for study.

Nematodes (roundworms)

· Earthworms

· Ticks (red tick)

Centipedes (drupe, nodule, polygonum)

Orthoptera (earwig)

Proboscis (cycad larvae, aphids)

Coleoptera (larvae of the oriental beetle, click beetle, ground beetle)

Lepidoptera (pupae and larvae)

· Hymenoptera (nests of sand wasps, bumblebees, ants).

Work on soil research in the field begins with choosing a location for a soil pit. This is very important, since the correctness of the conclusion about the soil of the entire site depends on the correct choice of location. Before choosing a location for the cut, you need to make one or more digs.

Soil sections should not be located near roads, near the edges of ditches, in microdepressions that are atypical for a given area, etc.

When choosing a location, they are guided mainly by the topography of the site, then by the vegetation and nature of the land (arable land, hayfield, forest, swamp, etc.). Observations and experience have established that the properties and quality of the soil are very closely related to the relief.

Therefore, soil sections, as a rule, should be evenly located on all elements of the relief: on watersheds, at the beginning, in the middle and at the end of a slope, on a plain, in a river valley, etc. In this case, the study will cover a wide variety of soil types, species and varieties in the study area.

It is quite clear that the density of the location of the main soil and control sections, as well as digging areas, largely depends on the relief. The more complex the relief, the more rugged the terrain, the more varied and complex the soil cover and, therefore, the more cuts need to be made per unit area. On the contrary, in conditions of flat terrain, where the soil cover is uniform, the distance between individual cuts can be much greater, and the total number of cuts per unit area is much smaller.

So, in a small study area, which is a smooth plain, it is enough to lay one section, which will characterize the soil of this area. If the flat area is large (an extensive watershed plateau or river terrace), then it is necessary to make several basic cuts and digs. The same will be required to characterize soils on long slopes of watersheds, even if they are of the same steepness, especially in cases where these slopes are dissected by gullies, ravines and gullies.

From the point of view of the difficulty or complexity of conducting soil research, territories are conventionally divided into five categories (N.P. Karpinsky, N.K. Balyabo, V.A. Francesson, A.I. Lyakhov).

• 1) steppe areas with dissected relief and uniform soil cover; on clearly isolated relief elements, soil complexes occupy no more than 10%;
• 2) territories of category I with soil complexes occupying 10-20%.

• 1) steppe, desert-steppe and forest-steppe areas with highly dissected relief, with a variety of rocks and heterogeneous soil cover;
• 2) territories of category I with soil complexes occupying 20-40%;
• 3) territories of category II with soil complexes occupying 10-20%;
• 4) forest areas that have been significantly developed for agriculture, with a clearly dissected topography and the presence of no more than 20% of wetlands.

• 1) forest areas, little developed for agriculture, with 20-45% of wetlands;
• 2) forest areas with highly complex soils;
• 3) steppe and desert-steppe areas with soil complexes occupying 40-60%;
• 4) floodplains, floodplains, river deltas with simple cover, with less than 20% of forested and bushy areas;
• 5) mountain and foothill lightly forested areas.

• 1) forest areas with more than 40% of the area occupied by swamps, or with very high soil complexity;
• 2) mountain and foothill forested areas;
• 3) floodplains, flood plains, river deltas with complex, heterogeneous soil cover (salinization, swampiness, etc.) or with more than 20% of forested areas;
• 4) tundra areas.

The density of soil sections also depends on the scale of the topographic base on which the soil map is compiled. The larger the scale, the more detailed the soil map and the more, therefore, soil sections must be made in a certain area and, conversely, the smaller the scale, the fewer sections have to be made in the study area.

The number of soil sections laid in the study area is determined by the scale of the soil survey and. category of area according to the difficulty of conducting soil research.

To establish the density of soil sections depending on the category of terrain and the scale of survey, you can roughly use the data given in Table. 80.

Each soil section (main, control and digging) is tied by eye on the ground, marked with a symbol on the soil map, numbered with a serial number and recorded in the field journal.

After selecting a location for the soil cut, mark a rectangle on the soil surface with a shovel. The pits should be such that you can freely descend into them and work. The usual sizes of the main cuts are as follows: length 150--200 cm, width 80 cm, depth 150--200 cm. One of the walls of the pit, facing the sun (to better see the color of the soil), is made vertical, and the opposite wall is made with steps every 30-50 cm, to make it convenient to go up and down.

When digging, it is recommended to throw the soil mass onto the long sides of the hole, with the turf or topsoil layer on one side, and all the underlying soil on the other. When the pit is ready, its front wall is refreshed with a shovel, individual genetic soil horizons are established, measured and described.

After describing the soil section and taking samples, the hole must be filled up. When filling up cuts, you should first dump the soil thrown out from the depths, and then cover it again with the top layer lying on the opposite side of the hole. This is done in order not to introduce diversity and spoil the fields, since the lower layers of the soil are usually infertile and require a long period of cultivation.

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