What does an artificial cut of soil look like? Methodology for field study of soils. Morphological properties of soils

Work on the study of soils in the field begins with the selection of a place for a soil pit. This is very important, since the correctness of the conclusion about the soil of the whole plot depends on the correct choice of the place. Before choosing a place for the cut, you need to make one or several pits.

Soil pits should not be located near roads, near ditch edges, in microdepressions atypical for this area, etc.

When choosing a site, they are guided mainly by the relief of the site, then by the vegetation and the nature of the land (arable land, hayfields, 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 relief elements: on watersheds, at the beginning, in the middle and at the end of a slope, on a plain, in a river valley, etc. types, species and varieties in the study area.

It is quite understandable that the density of the location of the main soil and control sections, as well as pits, largely depends on the relief. The more complex the relief, the more the terrain is crossed, the more variegated and more complex the soil cover and, therefore, the more cuts must be made per unit area. On the contrary, in conditions of flat relief, where the soil cover is uniform, the distance between individual sections can be much greater, and the total number of sections per unit area is much less.

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 (a vast watershed plateau or a river terrace), then it is necessary to make several main cuts and pits on it. The same is required for the characterization of soils on long slopes of watersheds, albeit of the same steepness, especially in those cases when these slopes are dissected by gullies, ravines and gullies.

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

1) steppe regions with dismembered 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 regions with highly dissected relief, with various 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, significantly developed for agriculture, with a clearly pronounced dissected relief and the presence of no more than 20% of swampy areas.

1) forest areas, poorly developed for agriculture, with the presence of 20-45% of wetlands;
2) forest areas with high soil complexity;
3) steppe and desert-steppe regions with soil complexes occupying 40-60%;
4) floodplains, floodplains, river deltas with an uncomplicated cover, with less than 20% forested and shrubby areas;
5) mountainous and foothill lightly forested areas.

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

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

The number of soil pits laid in the study area is determined by the scale of the soil survey and. a category of terrain according to the difficulty of carrying out soil research.

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

Each soil section (main, control and excavation) is tied visually on the ground, designate conventional sign on a soil map, numbered with a serial number and recorded in a field journal.

After choosing a place for a soil cut, a rectangle is marked on the soil surface with a shovel. The pits should be such that one can freely descend into them and work. Typical dimensions for 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 (in order to better see the color of the soil), is made vertical, and the opposite - steps after 30-50 cm, so that it is convenient to go down and go up.

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

After describing the soil section and taking samples, the pit must be filled up. When filling the cuts, you should first discard the earth thrown out of the depths, and again cover from above with an upper layer lying on the opposite side of the pit. This is done in order not to introduce variegation and not to spoil the fields, since the lower layers of the soil are usually infertile and require a long period of time for their cultivation.

Soil cuts are of three types: main (full) cuts, control (checking or half-holes), surface (digging holes).

the main (full) sections are laid to such a depth as to reveal the upper horizons of the unchanged source rock. Usually this depth is on average 1-2 meters. Such sections are used for a special detailed study of the morphological properties of soils and the taking of samples for physical and chemical analysis.

Control cuts are laid at a shallower depth from 0.75 to 1.5 meters. They serve to study the thickness of the humus horizons. If, during the description of the half-hole, new signs were discovered that were not previously noted, then at this place it is necessary to lay a full section.

Surface sections are usually laid in places where one soil is supposed to change to another. The depth ranges from 0.40 to 0.70 meters.

The cut is usually positioned so that its front wall, intended for description, is facing the sun in order to avoid sun glare interfering with the correct assessment of the soil. Three walls of the cut should be vertical, the fourth with steps. The soil of the cut must be thrown out on the sides and not on the front sides. The upper (humus) horizon is thrown to one side, and the lower layers to the other side of the cut, so as not to mix with the upper fertile layer.

General view of the soil section

Immediately after description and sampling, the incision must be carefully filled in.

7.Morphological description of the soil section

Section No. 1 Ivolginskaya depression in the vicinity of the village of Kalyonovo

horizon name	Power cm	description
A 0 forest litter		Does not boil from HCl; there is poorly decomposed needles, branches, leaves; loose; dry; smooth transition;
A1 Humus-accumulative		The border is expressed along the border of the roots; the color is brown; dense; structural aggregates penetrated by the roots are lumpy; does not boil with HCl; fresh; half-decomposed tree roots are found; slightly acidic reaction of the environment; the transition boundary is wavy, expressed in color, along the roots;
		The color is brown, dense, the horizon is pierced with roots, the structure is lumpy, does not boil from HCI
[A] Burial layer		The transition border is wavy; the color is green-gray; the horizon is compacted; small roots are found; lumpy structure; does not boil from HCl; dry; wavy transition;
		Not uniformly colored; the main background is yellow-gray; there are glimpses of a sandy loam composition; does not boil with HCl;
		The color is not uniform, yellow-gray; roots are found; boils violently with HCl; dense; lumpy; fresh;
		The color is yellow; carbonate deposits are present; boils violently with HCl; dense horizon; fresh;

Section No. 2, Ivolginsk settlement, 150-200 m westward from the Ulan-Ude - Kyakhta federal highway, on arable land.

horizon name	Power cm	description
And arable		Dark brown, dense, there are small roots, the structure is not strong, lumpy, fresh, the boundaries of the transition point are dark wavy, expressed in color
In chestnut		Dense, dirty yellow, there are single roots, does not boil from HCl, the transition boundaries are even expressed in boiling
		Dirty yellow color, heavy composition, dense
		Dry, there are single roots, there are inclusions, lumpy

Soil cuts, depending on the purpose, are divided into main (deep), half-cuts (half-holes) and pits. The main section is established to identify soil type and should cover the entire soil column, including the top of the source rock horizon. Its depth is determined by the depth of penetration of the soil-forming process and usually fluctuates from 150 to 300 cm. The main sections are laid on all new relief elements, when vegetation and parent rocks change. Half-sections are used to establish the subtypes and varieties of soils in the study area and to determine the boundaries of the distribution of different soils. The depth of the half-incisions is 75-100 cm. If, when studying the half-incision, a new type of soil or a change in the parent rock is revealed, the half-incision is deepened until the full incision. Pits 25-75 cm deep are made to establish the boundaries of the distribution of certain types, subtypes and varieties of soils. The average ratio between the main cuts, half-holes and ditches is 1: 4: 5.

The decisive moment is the choice of the incision site. The incision should be made under conditions typical of the area under study. It is impossible to lay a section 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, atypical for the entire site. Before laying the incision, carefully study the area for the characteristics of which the incision is laid. If the study area is a plain, the cut shall be made in the center of the plain. If a slope is being investigated, a full cut is made in the middle of the slope and a half-hole in the upper and lower portions. Quite often, within the limits of one relief element, the microrelief gets a vivid expression, which can be especially often observed in flat plain territories, and the microrelief here is represented by a complex of barely noticeable microhighs (hillocks) and microdepressions (saucer-like depressions). In this case, two cuts are laid: one at the micro-increase, the second at the micro-decrease.

Cut digging technique... For the cut, a rectangle is marked with a length of 120-150 cm and a width of 60-80 cm. The short side of the cut serves as the front side along which the description of the soil is made. This side should be better lit, i.e. must face the sun. This wall of the cut, as well as its two sides, are made completely vertical. On the fourth side, steps are made for descending into the cut. When digging, the soil is thrown to the left and right of the front wall. A mass of the upper humus horizon is thrown on one side, and a mass of deeper horizons on the other. It is unacceptable to throw soil or trample on the front side of the cut. After the end of 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 digging the section, its location is as accurately as possible applied to the topographic base. The main cuts are indicated by crosses in circles, half-holes - by circles, holes - by dots with the obligatory indication of the number. All types of sections are numbered in the diary. To bind the section, i.e. accurate plotting of its location on a topographic base, first of all, they are guided by the terrain on a map using a compass. The map is oriented by the compass in such a way that the northern end of the compass needle coincides with "C" in the direction of the arrow on the map. Then, taking on the compass the direction to the cut from any well-visible landmark (intersection of roads, the angle of the crop rotation field, buildings), determine the distance between them and use the measuring ruler to lay this distance in the appropriate direction. The distance is determined by eye - in steps, having previously established the price of a step (its value in centimeters). You can use the serif method. An arbitrary point is placed on a small sheet of stencil, and lines are drawn from it through the scale ruler to two landmarks. Then the wax is applied to the topographic base so that each of these directions passes through the corresponding landmark sign. The intersection point of the directions is the location of the section; it is shipped from wax to card.

On the map and in the field diary, they put the number of the section and describe it. The sequence number of the section and its location are noted in the diary; accurately indicate the element of relief and microrelief on which the section is laid (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 with an indication of the mechanical composition, the presence of boulders, carbonate gravel, readily soluble salts. The level of soil and ground waters, their quality and the nature of swamping (gleying) - surface or ground are noted. They also note the degree of erosion (washout) of the soil, and on arable land they describe the nature of its surface (evenness, blockiness, fracturing, the presence of a crust) and the degree of stony. If stones (boulders) on the surface of arable land are less than 10%, stony is considered weak, with 10-20% - medium, and more than 20% - strong.

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

The front side of the incision is prepared with a knife or small spatula in such a way as to obtain its natural fracture. By the nature of color, neoplasms, constitution and other morphological characteristics, genetic horizons are distinguished, the boundaries between them are drawn with a knife. Then a cloth meter is strengthened along the wall of the section 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 draw a profile with colored pencils, show the depth of penetration and the nature of the development of the root system, note the neoplasms, and then examine the effervescence and gleying.

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

The description should be short and clear, without wasting words.

It is necessary to determine the geographic position of the section and make a reference (outline).

Mark the nature of the relief, indicate exactly on which relief element the cut is made. Note parent and underlying rocks and water table depth if found.

Determine the vegetation (composition, density, condition), since plants have a huge impact on soil formation. One of the most productive components of biomass is litter. Therefore, it is recommended to determine the type of litter: mor, moder, mull. 1) Coniferous litter, together with coarse humus, forms a litter of the pestilence type, humus has a fulvate character, and soil formation proceeds according to the podzolic type; 2) In mixed and deciduous forests with rich herbaceous vegetation, humate-fulvate humus of the moder type is synthesized; 3) Under the canopy of herbaceous steppe or meadow vegetation, with a significant mass of dying roots, a soft humus of the mule type of humate composition is formed and the soil formation process, respectively, is soddy.

Determine the condition of the surface (boggy, bumpiness, fracturing, salinity, stony and other characteristic features).

Describe the land and its condition, give an agronomic assessment of the soil, taking into account the data on the agricultural value of the soil.

Attention: acquaintance with the relief, vegetation, its condition and other characteristic features of the section where the section is made is carried out in the period of time that is necessary for digging the section intended for study.

When the pit is ready, it is necessary, first of all, to determine the nature of the soil-forming rock, salinity, and the degree of moisture. Record all data in a notebook (field journal).

In order to highlight genetic horizons, noticeable horizontal lines are drawn between them with the edge of a knife. Another vertical line (scratch) is drawn with the sharp end of a knife from top to bottom of the soil cut and the density and composition of the soil is revealed. (Taking into account the density of soils facilitates the identification of horizons and the establishment of their boundaries). With a knife, break off pieces of soil to determine the surface of the soil fracture.

The power is determined by the previously attached centimeter. each horizon or subhorizon of soils, followed by a detailed study of their morphological and genetic characteristics: granulometric composition, physical properties and other features (color, structure, moisture, density, duty cycle, neoplasms, inclusions, root system).

For more full description for morphological signs, it is necessary to take soil smears. To do this, wet soil, taken from different genetic horizons at the tip of a knife, must be applied to a separate form or to a page of a notebook, arranging it in a column (on the left side, separate about a third of the page). Indices of genetic horizons should be indicated next to the sketch and strokes.

Sketch the soil profile with colored pencils.

Take soil samples for analysis, and, if necessary, a monolith. At the same time, a label must be included in each sample indicating the site of work, section number, depth of selection, surname of the performer and date of selection.

Perform simple chemical analyzes: (to determine the acid-base regime and carbon content of individual horizons, the presence of chloride and sulfate salts, iron, etc.), which do not require complex equipment.

Attention: the rules for determining the depth and nature of soil boiling from a 10% solution of hydrochloric acid (HC1). To do this, an oilcloth centimeter is fixed on the freshly prepared front wall of the incision so that zero coincides with the soil surface. Then, hydrochloric acid is successively dripped onto the soil from top to bottom, which, in the presence of calcium carbonates, produces “boiling” of varying intensity (weak, medium, strong or violent). In that part of the wall, where the depth and character of boiling from hydrochloric acid were determined, soil samples cannot be taken. Display the results of the study in the field book in a special column.

Give a field definition of the soil, establish its value. In the name of soils, it is necessary to reflect the type, subtype, species, variety and parent rock, for example: ordinary chernozem, medium-thick heavy loam on loess.

Outline the approximate boundaries of the distribution of this type of soil in the study area.

In conclusion, it is necessary to give an agronomic characterization of soils, defining soil properties important for agriculture and briefly describe measures for the rational use of soils.

The agronomic characterization of soils is based on the assessment of the following indicators: 1) the structure of the soil profile (alternation and thickness of genetic horizons, especially the thickness of the humus layer, structural state, density and porosity, thickness of fine-earth strata); 2) granulometric and mineralogical compositions; 3) chemical composition; 4) physical chemical properties; 5) soil cultivation; 6) the degree of erosion; 7) boggy.

The soil section after its examination, description and sampling should be closed.

Soil research methods

Soil color

Soil color is in direct proportion to its chemical composition. The more humus the soil contains, the darker the horizon is. The presence of iron and manganese gives the soil brown, ocher, red tones. Whitish, white tones suggest the presence of podzolization, salinization, salinization, and carbonization processes. All color changes are a reflection of changes in the intrinsic properties of the soil material.

Wet soil has a darker color than air-dry soil, so it is very important to indicate when describing the degree of its moisture.

The lighting should be uniform over the entire soil profile, as the soil looks darker in the shade and it is easy to make mistakes when determining its color. It is advisable to check the color of the soil in samples brought to an air-dry state, that is, well dried in a dry room or in the air (but not in the sun).

When determining the color of the soil, one should take into account the type of lighting - solar or artificial, changes in shades are possible.

The color of the structural units can differ significantly from the color of their inner part due to the formation of a surface crust and drip films, which can provide important information on the genesis of the soil.

The same soil in its natural state and ground into powder has a different color.

Soils are rarely painted in any one pure color. Typically, the color of soils is quite complex and consists of several colors (for example, gray-brown, whitish-gray, reddish-brown, etc.), with the name of the predominant color being put in last place.

To determine the color of the soil horizon, it is necessary: to establish the predominant color; determine the saturation of this color (dark, light-colored); note the shades of the main color (for example, brownish-light gray, brownish-brown, grayish-fawn, etc.).

Color uniformity:

Uniform coloration - the entire horizon is uniformly colored in some color. The options are: uniform uniform color and uneven uniform color, when the tone and intensity of the color gradually change from the upper part of the horizon to the lower one.

Inhomogeneous coloration - the horizon is colored in different colors by alternating spots of different colors and different configurations.

Inhomogeneous color happens: Spotty - spots of one color are irregularly located against a background of another color;

Speckled - small (up to 5 mm) spots of the same color are irregularly scattered over a uniform background; Striped - regular alternation of stripes of different colors; Marble - variegated color of spots and veins of different colors.

For example, the color of the soil is brownish-gray, inhomogeneous, against a gray background there are brown and rusty spots and smears.

Soil moisture levels

In field research, five degrees of soil moisture should be distinguished:

Dry soil is dusty, the presence of moisture in it is not felt to the touch, does not cool the hand, soil moisture is close to hygroscopic (moisture in an air-dry state);

The moist soil cools the hand, does not get dusty, and brightens a little when it dries.

Moist soil is clearly felt to the touch, the soil moisturizes the filtered paper (napkin), when it dries, it brightens significantly and retains the shape given to the soil when squeezed by hand.

Damp soil, when squeezed in the hand, turns into a pasty mass, and water wets the hand, but does not ooze between the fingers;

Wet soil, when squeezed in the hand, water is released from the soil, which oozes between the fingers, the soil mass shows fluidity.

Types and purpose of soil sections. The method of direct study of soils in the field is based almost entirely on the elucidation of the morphological characteristics of soils.

The study of soils is carried out mainly on soil sections, which are a specially dug hole of one depth or another. According to the purpose, the cuts are main, half-holes, or control, and ditches.

The main sections are made in places that are most typical for the study area, both in terms of relief and vegetation. In the study of arable land, they are guided primarily by the terrain, and in the study of virgin lands, in addition, the nature of the vegetation is taken into account.

The incisions are usually made to full depth (1.5-2 m and deeper) so that the parent material can also be discovered and studied. In cases where groundwater occurs close to the surface, the main sections can be up to 1 mm deep or even less. Soil samples are taken from these sections from all genetic horizons, as well as from the parent rock.

The choice of a place for laying the main cuts should be made especially carefully.

We, or control cuts, are dug to a shallower depth than the main ones. With their help, they check whether the soil is the same at the locations of the control and main cuts.

The control cuts are made much more than the main ones. Samples are sometimes taken from them. The soil in the control sections is described more concisely than in the main ones.

Prikopki serve to establish boundaries between soil varieties and to highlight the contours of these varieties. Digging is done to a depth of 30 to 50-70 cm. The soil in the pits is not described, only its name is recorded.

Arrangement and carrying out of soil sections. Work on the study of soils in the field begins with the selection of a place for a soil pit. This is very important, since the correctness of the conclusion about the soil of the whole plot depends on the correct choice of the place. Before choosing a place for the cut, you need to make one or several pits.

Soil pits should not be located near roads, near ditch edges, in microdepressions atypical for a given area, etc.

It is quite understandable that the density of the location of the main soil and control sections, as well as pits, depends to a large extent on the relief. The more complex the relief, than

the more the terrain is crossed, the more variegated and more complex the soil cover and, consequently, the more cuts need to be made per unit area. On the contrary, in conditions of flat relief, where the soil cover is uniform, the distance between individual sections can be much greater, and the total number of sections per unit area is much less.

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

I category. Steppe regions with flat or gently undulating, slightly dissected relief and uniform soil cover. Soil complexes occupy no more than 10% of the study area.

2) forest areas with high soil complexity; 3) steppe and desert-steppe regions with soil complexes occupying 40-60%; 4) floodplains, floodplains, river deltas with an uncomplicated cover, with less than 20% forested and shrubby areas; 5) mountainous and foothill lightly forested areas.

3) floodplains, floodplains, river deltas with a complex, heterogeneous soil cover (salinization, swampiness, etc.) or with the presence of more than 20% of forested areas; 4) tundra regions.

The density of the location 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 cuts must be made in a certain area and, conversely, the smaller the scale, the fewer cuts must be made in the study area.

The number of soil pits laid in the study area is determined by the scale of the soil survey and. a category of terrain according to the difficulty of carrying out soil research.

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

Each soil section (main, control and ditch) is tied eye-to-eye on the ground, marked with a conventional sign on the soil map, numbered with a serial number and recorded in a field journal.

After choosing a place for a soil cut, a rectangle is marked on the soil surface with a shovel. The pits should be such that one can freely descend into them and work. The usual dimensions 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 (in order to better see the color of the soil), is made vertical, and the opposite one - steps after 30-50 cm, so that it is convenient to go down and go up.

When digging, it is recommended to throw the soil mass on the long sides of the pit, with the sod or arable layer on one side, and all the underlying land on the otherguyu. When the pit is ready, its front wall is refreshed with a shovel, separate genetic soil horizons are established, measured and described.

Description of soil sections. Morphological features of the soil profile. When describing soils during field research

are guided by the following most important morphological features of the soil profile.

Soil structure (i.e., the division of the soil layer into genetic horizons).

The thickness of the soil horizons and the depth of their occurrence. The thickness of the soil horizons is measured in centimeters along a plumb line, from top to bottom, for example: arable 0-23 cm, podzolic 23-27, illuvial 27-100 cm etc.

Coloring of soil horizons. Soil color is one of the most important external signs, which are usually guided when judging the internal properties of the soil, as well as when the soil layer is divided into a number of genetic horizons. When describing the soil, it is necessary to give as simple a definition of the basic color as possible, for example: black, dark gray, gray, light gray, whitish, etc. It should be borne in mind that wet soil has a slightly darker color than dry. Therefore, when judging the color of the soil, it is necessary to take into account the degree of its moisture content, and the final conclusion about the color of the soil must be given when the soil samples taken in the field are air-dry.

The content of humus in the soil (determined by the intensity of the color of the upper horizon).

The composition of the soil and its individual horizons (i.e., the external expression of the porosity and density of soils).

Inclusions and neoplasms. Of inclusions in soils, granite and calcareous boulders are most often found, from new formations - compounds of carbonic lime, iron, manganese, gypsum, as well as an accumulation of readily soluble salts.

Soil structure for individual horizons. The determination of the soil structure in the field is usually done by eye when the earth is thrown out of the pit. When describing, the degree of expression of the soil structure should be indicated, for example: distinctly nutty, distinctly granular, indistinctly pronounced, outlined lamellar structure, well-pronounced columnar, etc.

The mechanical composition of the soil. Recognition of the texture of the soil in the field is usually done by eye and touch. So, dry clay is crushed by a finger and eats into the pores of the skin of the fingers, while wet clay is easily kneaded and takes any shape. When rolling a lump between the palms of the hands, the clay produces thin cords. When kneading it with your fingers, sand is not felt. Heavy loam is rolled into a cord, which, when bent into a ring, forms cracks. When wet, medium and light loams are rolled into a cord; when rubbing between the palms, the sand is clearly felt. Sandy loam in a raw state either does not roll out into a cord at all, or this cord breaks already during rolling; There are a lot of sand particles here and they noticeably scratch the skin of the fingers. Sandy soils are very loose and are not able to roll out into a cord.

Soil moisture. When describing the soil, it is necessary to take into account the degree of moisture and the nature of soil moisture. If the pit reaches the groundwater, the level of the latter is noted.

The depth and nature of the distribution of the root system of plants.

The nature of the parent, or parent, breed.

These are the main features that should be reflected in the description of soils in the field.

It should be noted that in swampy areas, where, due to the close occurrence of soil and groundwater, it is extremely difficult to dig a hole with a shovel, it is often necessary to use a soil or peat drill.

When describing bog-type soils, special attention should be paid to the following features: the thickness of the living vegetation cover and its botanical composition, which characterizes the belonging of a given bog massif to one or another subtype of bogs; the total thickness of the entire peat layer; the degree of decomposition or mineralization of the peat mass (poorly decomposed, semi-decomposed and highly decomposed peat); the mechanical composition of the soil and the degree of its deoxidation, or gleying; the depth of soil and groundwater; the nature of humidification (ground, atmospheric, mixed).

Factors of soil formation. The description of soils must be accompanied by notes on the nature of the vegetation and the cultural state of the land (arable land, pasture, fallow land, hayfield, forest, swamp, etc.). At the same time, it is very important to note the degree and nature of the development, or cultivation, of the described land (for example, newly developed arable land, old arable, limy, gypsum, drained, irrigated, planted, etc.).

If the cut is made on arable land, the condition of the crops should be noted and their quality assessed. Very often on appearance plants, you can accurately judge the quality of the soil and its fertility.

The best expression of the quality of dissimilar soils is the plants growing on these soils. In cultural areas, this role is best played by cultivated plants, especially when the student of the soil is already familiar with the area. In areas not covered cultivated plants, an indicator of soil quality is wild flora.

Especially great importance has a study of vegetation in meadows and pastures. At the same time, the difference in soil qualities is indicated not only by the difference in the botanical composition of the flora, but also by the degree of development of plants.

It is very important to carefully study the soil-forming rocks and the geological structure of the area, hydrological conditions and relief.

A thorough study of the natural-historical conditions of soil formation makes it possible to more fully and deeper understand the genesis and originality of the studied soils and correctly establish those agrotechnical measures with which it is possible to further improve these soils when using them in agriculture... The study of soils in nature is unthinkable without a thorough study of the factors of soil formation.

Chemical properties of the soil. In a field study of soils, it is possible to perform only some and, moreover, the most simple chemical tests; a detailed and comprehensive study of the chemical composition of soils is the task of the subsequent laboratory processing of the material collected in the field.

In the field, they usually determine the presence of carbonates in the soil (reaction of the soil solution pH), the content of sulfate, chloride salts and ferrous compounds of iron.

The presence of carbonates (CaCO 3, MgCO 3 ) is determined using 5-10% hydrochloric acid. To do this, a solution of hydrochloric acid is applied to the wall of the soil cut with a dropper and the depth from which boiling begins, as well as the intensity of boiling, is determined. In soils rich in carbonates, effervescence is found sharply; with a low content of carbonates in the soil, effervescence is weak, and in the absence of carbonates, it does not manifest itself at all.

Thus, by the character of boiling, one can judge not only about the presence of carbonates in the soil, but, to a certain extent, about their amount.

It is most convenient to determine pH using a universal indicator that allows you to obtain data in the range from 4 to 8 with an accuracy of 0.25-0.5.

To determine the presence of chloride and sulfate salts in the soil, a small amount of extract is prepared using distilled water, to individual samples of which BaCl 2 is added in test tubes and AgNO 3 ... The appearance of a white precipitate or turbidity in a test tube with BaCl 2 will indicate the presence of sulfate salts, and in a test tube with AgNO 3 - chloride salts in the soil.

Normal soda content (Na 2 CO 3 ) in the soil is found when a cherry-red color appears after adding a few drops of an alcoholic solution of phenolphthalein to the water extract.

The presence of ferrous oxide in the soil is determined by the blue discoloration of the soil from a drop of fresh solution of red blood salt [K 3 Fe( CN) 6 ].

All the results of studies of the chemical properties of the soil, as well as the results of morphological studies, are recorded in detail in a field journal.

As a result of a careful study of the soil in the field, the type and variety of the studied soil is established, its agricultural production characteristics are compiled, and the measures necessary to increase the fertility of this soil when used in agricultural production are outlined.

Taking soil samples and monoliths. After the description of the main section, they begin to take soil samples for laboratory research.

Samples are taken from each genetic horizon. With a knife or chisel, cut a rectangular piece with an edge length of about 8 cm from a typical part of the horizon. If the thickness of the soil layer is large, then 2 samples are taken: from the upper and lower parts of the horizon separately. The weight of the samples depends on the purpose of the subsequent laboratory processing (most often 0.5-1 kg).

Each sample is appropriately labeled, wrapped in wrapping paper and tied with twine. The label records the section number, genetic horizon, depth from which the sample was taken, as well as the date of sampling; all these data are signed by the researcher. Without a label, the sample taken is irrelevant. The number of samples in the section depends on the number of soil layers (in the main section, there are usually 4-5 of them).

For the agronomic characterization of the soils, mixed samples from the arable layer are also taken from each section. A mixed sample is usually made up of 5 soil samples (each weighing 0.5-1 kg), taken from a small area (100-400 sq. m) around the cut and in the main cut itself. These samples are mixed for

a sheet of paper and from the mixture take an average sample weighing about 0.5 kg. One mixed sample should characterize a defined area of up to 10 ha.

Mixed samples are used mainly in the study of soils in the sod-podzolic and northern part of the forest-steppe zone for mass laboratory analyzes necessary for drawing up cartograms of soil acidity and the provision of soils with phosphorus and potassium.

In addition to soil individual and mixed samples, in field research, soil monoliths with undisturbed structure, composition, and structure are sometimes taken. A well-taken soil monolith makes it possible to supplement and check all morphological observations and records made in the field regarding the color of the soil, its structure, structure, the allocation of horizons, etc.

Monoliths taken from typical sites of the investigated area allow one to visually compare all features selected soil varieties. Finally, soil monoliths can serve as a valuable museum and visual teaching material for agricultural universities, technical schools, and experimental stations.

Monoliths are placed in special wooden boxes of certain sizes. To take the monolith from the main section, the pit is slightly widened and deepened. When excavating a soil monolith, a rectangular column is cut out on the vertical wall of the pit according to the size of the box; the frame of the box is then put on this column, to which the lid is screwed after cutting off the protruding parts of the soil. After that, the column is poured in from the sides and gradually rolled off. The excess soil is removed from the monolith with a knife flush with the edges of the frame and the lid is screwed on. On the lid of the box, they write the number of the section, the place where the monolith was taken from, and the name of the soil.

When studying bog soils, peat samples must also be taken from different horizons, since in most cases the peat mass is heterogeneous in its thickness, not only in the degree of peat decomposition, but also in chemical properties.

Peat samples are usually taken from the upper, middle and lower peat layers. Along with peat samples, it is necessary to take samples from the mineral soil layer, which lies directly under the peat layer. Thus, a clear idea of the full profile of the studied peat soil, its genesis, its main properties and agronomic value will be obtained.

Soil samples on peat soils are best taken with a peat drill.

- A source-

Garkusha, I.F. Soil science / I.F. Garkusha.- L .: Publishing house of agricultural literature, magazines and posters, 1962.- 448 p.

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