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Part 1. PROPERTIES, CLASSIFICATION, DISTRIBUTION OF SOILS
MORPHOLOGICAL PROPERTIES OF SOILS
FIELD SOIL INVESTIGATION TECHNIQUE
In the field, they study and determine the soil and give them a name according to the external, so-called morphological features, which reflect the internal processes taking place in soils, their origin (genesis) and development history.
N. M. Sibirtsev believed that according to morphological (external) features, one can define soil, just as we define a mineral, a plant, or an animal. Therefore, in the field, it is especially important to correctly describe soil, note all its signs.
To describe soils, study their morphological features, establish boundaries between different soils, and take samples for analysis, special pits are laid, which are called soil cuts. They are of three types; full (basic) cuts, half-holes and pits.
First of all, it is necessary to carefully inspect terrain, determine the nature of the relief and vegetation for right choice locations of the soil section.
Incision needed lay in the most characteristic location of the surveyed area. Soil cuts should not be laid near roads, next to ditches, on microrelief elements atypical for the given territory (depressions, bumps).
In the selected area of the terrain, they dig a soil section so that its three walls are sheer, and the fourth descended stairs(Fig. 1).
Rice. 1. Soil section
The front, front, wall of the incision, intended for description, should be facing the sun.
When digging a cut, the soil must be thrown away only on the sides and in no case on the front wall, which can lead to its pollution, destruction of the upper horizons, changes in their thickness, etc.
Full, or basic, incisions laid to such a depth as to open 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 purpose 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 analyzes.
Half holes, or control cuts, are laid to 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 effervescence from hydrochloric acid and the occurrence of salts, the degree of leaching, podzolization, alkalinity, and other features, as well as to determine the area of distribution of soils characterized by complete sections. If, when describing the half-pit, new signs were found that were not noted earlier, then a full section should be made at this place.
Pit marks, or small superficial cuts, with a depth of less than 75 cm, 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 supposed to change to another.
Descriptions of soil cuts, hollows and pits are entered in diary, in which, in addition, information about the relief, vegetation, groundwater, the results of field studies of the physical, chemical and other properties of the soil should be recorded. Approximate form field soil diary is given below. It is necessary to pay special attention to these signs and study them most carefully.
Rice. 2. A sample diary design for describing a soil section:
|
Month _______ y 1. Section No. _____________________ 2. Oblast _____________________________________ District ____________________________________ 3. Village council, collective farm, state farm ________________________________________________________________ 4. Item ________________________________________________________________________________ 5. General relief __________________________________________________________________________ 6. Microrelief _________________________________________________________________________ 7. The position of the section relative to the relief and exposure _______________________________________ 8. Vegetation cover ____________________________________________________________________ 9. The site and its cultural condition _____________________________________________________________ 10. Signs of waterlogging, salinity and other characteristic features _____________________ 11. Depth and character of effervescence from HCl ________________________________________________________ 12. The level of soil and groundwater _________________________________________________________ 13. Parent and underlying rock ____________________________________________________________ 14. Soil name ____________________________________________________________________________ The main morphological features that determine the soil in the field: 1) the structure of the soil profile, 2) the color (color) of the soil, 3) the degree of moisture (as well as the level of groundwater or top water), 4) mechanical composition, 5) structure, 6) addition, 7) neoplasms. |
Sample form for description of soil section:
- Part I. Properties, classification, distribution of soils
- Definition of the concept of "soil", its place in nature and life
- Morphological properties of soils
- Soil Field Research Technique
- Part 2. Soil guide
- Part 3. Systematic descriptions of soils
On the site of the ecological center "Ecosystem" you can also get acquainted with abstracts and articles on soil science.
| Parameter name | Meaning |
| Article subject: | SOIL SECTION |
| Rubric (thematic category) | culture |
WHERE TO BEGIN? GARDEN LAND DEVELOPMENT
VEGETATION - INDICATOR OF SOIL PROPERTIES
Suppose you have received an uncultivated or uncultivated piece of land for your garden. First of all, you need to find out what kind of soil you got, what its properties are, and in accordance with this, develop measures for its development.
First of all, look at what is growing on it. Vegetation is a good indicator of soil properties. If sorrel, sedges, ranunculus, hawkweed, horsetail, cinquefoil, daisies, meadow cornflower, mountaineer pochuchuy have flourished on your site, this means that the soil is acidic and waterlogged. On slightly acidic, well-drained soil, you will see other plants: alfalfa, clover, burdock, coltsfoot, cornflower, mountaineer. Field mustard, goose foot, tar, thistle, sweet clover, euphorbia, chamomile (navel) testify to compacted soil poor in humus. Another group of plants, on the contrary, loves fertile, cultivated soils and immediately develops a field abandoned by man - quinoa, thistle thistle, wood lice, and gout.
If there are a lot of nettles on your site, this is a good sign. Nettle roots have a beneficial effect on the surrounding soil, contributing to the accumulation of fine dark humus.
After you have studied the surface of your site, you need to see what is in it in the depths. If you make a so-called soil cut, you will immediately get answers to many important questions. A soil cut will give you a wealth of information about your soil.
Dig a hole 60-70 cm deep so that one wall is strictly vertical and level, on the opposite side, for convenience, one or two steps can be made. On a vertical wall, you can trace all the layers, or, as soil scientists say, soil horizons, that make up your soil, and determine many of their properties. Next, we describe what can be seen in the soddy-podzolic soil section, the most common soil type in the Non-Chernozem zone of Russia.
Anterior wall of the incision
A1 - arable horizon A 2 - podzolic horizon B - illuvial horizon
Rice. 5. Soil section. Profile and front wall of the section on soddy-podzolic soil
The topmost layer, dark-colored and riddled with roots, is the humus horizon. This is the layer that will nourish the roots of your plants. For this reason, its properties are especially important. First of all, its color characterizes the content of humus in it. Usually the color of the humus horizon ranges from light brown to dark brown; the darker it is, the higher the humus content.
By the physical properties of the humus horizon, you will find out what kind of soil you got - light or heavy (in the language of soil scientists - the mechanical or granulometric composition of the soil). This will go a long way in helping you figure out what to expect from her. There is a simple test: a lump of moist soil is placed on the palm of your hand and a cord is rolled out of it.
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If the cord immediately breaks into pieces, then you have light sandy soil. Try twisting the cord into a ring. If it does not crack at the same time, then you have heavy clay soil. If numerous cracks appear on the ring, it means that the soil is loamy with the most favorable ratio of sand and clay particles for agriculture. Both sandy and clay soils, each in its own way, give the gardener a lot of trouble. Sandy soils do not hold water and nutrients well; for the most part, these are marginal soils poor in organic matter. However, they also have a number of positive properties: sandy soils are almost never threatened by waterlogging and stagnant water, and, in addition, they are warm and warm up quickly. Thanks to these properties, in the spring they are ready for sowing earlier than others. Heavy soils, on the contrary, are called cold, as they warm up very slowly. Οʜᴎ do not pass water well. Unstructured clay soils dry out into a solid stone, and after rains, water stays on their surface for a long time. But cultivated clayey and, especially, loamy soils are rich in organic matter and have high fertility. With the right system of measures, light soils can also be made highly fertile.
On the soil section, you can also see if the humus horizon has a cloddy structure and if there are many earthworm passages in it. Both are an important indicator of fertility. Next, you can measure the thickness of the humus horizon. It is worth saying that for the normal development of plants, it is required that its thickness be at least 15 cm. If it is less than 15 cm on your soil, then you will need to take measures to gradually cultivate the underlying layer and involve it in processing.
If your soil was once arable, then the humus layer has a clear lower boundary at a depth corresponding to the depth of plowing. If it is virgin soil, then the humus layer gradually passes into the underlying podzolized layer, which has a light, whitish color. This is a completely barren layer with a strongly acidic reaction. The thinner it is, the better for you. When digging up a site, in no case should it be touched and turned out to the surface. It can only be gradually cultivated, very slowly increasing the depth of digging.
Under the podzolized layer there is a dark brown compacted layer, the so-called illuvial horizon. It usually accumulates mineral nutrients washed out by rainwater from the upper horizons. And even lower, usually at a depth of more than 1 m, is the parent rock, unaffected by soil formation, on which this soil arose. Most often it is brown loam or red-brown moraine, a trace of the great glaciation that covered the entire north and the middle of the European part of Russia. The moraine contains a lot of pebbles and stones of various sizes.
The presence of waterlogging is evidenced by bluish-gray spots and interlayers, the color of which is due to the formation and washing out of ferrous forms of iron in conditions of poor oxygen access. If such spots are present in the humus horizon, this is a very bad sign, indicating a high level of groundwater.
If you got a site on a former swamp, then on the soil section you will mostly see two layers. Upper, humus, very dark, with a high content of humus or peaty, which is a layer of peaty, slightly decomposed plant mass. Below is a layer of viscous dark brown or bluish clay, less often sand. This, of course, is not the best option for a garden, and even more so for fruit trees. Only the creation of high embankments or beds of such a height that the root system of cultivated plants does not suffer from waterlogging from below by high-lying groundwater can save the matter. And of course, it is extremely important to try to lower the groundwater level with drainage ditches that will lead excess water outside the site.
The highest level of natural fertility in the Non-Chernozem zone is possessed by floodplain soils formed as a result of the gradual deposition of river sediments. It is worth saying that they are characterized by a deep humus horizon (up to 40-50 cm) with a high content of humus. The dark brown color of this horizon gradually becomes lighter downwards in accordance with the gradual decrease in the humus content. The humus horizon usually has a good cloddy structure and a neutral reaction.
In the Non-Chernozem zone, there are a lot of soils that suffer from waterlogging, and gardeners, as a rule, get far from the best plots (well, if not an outright swamp). Waterlogging is often due to the presence of a compacted underlying layer. To check if your area will suffer from waterlogging, it is recommended to do the following test. Dig a hole 15 cm in diameter and 30 cm deep. Pour water into it. When the water has completely seeped into the soil, pour it again. The second time you should note the time, ĸᴏᴛᴏᴩᴏᴇ leaves for the complete infiltration of water. If it takes more than 8 hours, then you have poorly drained soil. In the event of heavy rains, water will slowly seep into the depths and the top layer will be waterlogged for a long time.
Another test will help you find out if your plants will suffer from drought, that is, to find out what the water-holding capacity of your soil is. A small piece of land is heavily watered. After 2 days, a hole 15 cm deep is dug here. If the soil is completely dry to this depth, it means that it does not retain enough water to provide good growth plants.
SOIL CHEMICAL ANALYSIS, ACIDITY
Now that you've explored everything you can see with your eyes and feel with your hands, consider chemical soil analysis if you have the opportunity to do so. The soil on your site should not be exactly the same in different parts of it. To obtain an average soil characteristic of the entire area, a mixed soil sample is taken and sent for analysis. To do this, they take soil with a shovel in three or four places, preferably to a depth of 15-20 cm, mix it and select the amount necessary for analysis. The soil sample should only be stored dry.
The most important type of soil analysis is the determination of soil acidity, or pH value. The entire scale of soil acidity is divided into 14 pH values. It is generally accepted that a neutral soil reaction corresponds to pH 7. At lower values, the soil is acidic, at higher values it is alkaline. The availability of many nutrients for plants depends on the acidity of the soil. With a neutral reaction, the batteries are in the most accessible form.
The acidity of the soil can be determined by indicator (litmus) paper. A small sample of soil is saturated with rainwater or distilled water and indicator paper is applied to it. The red color of the paper indicates a strongly acid reaction, orange - medium acid, yellow - weakly acid, yellowish-green - neutral, bright green (or blue) - alkaline. Acid and alkaline reactions are unfavorable for the activity of microorganisms and, consequently, for the formation of humus from decaying plant residues. Soddy-podzolic soils most often have an acidic and slightly acidic reaction. By determining the pH of your soil, you will know if you need to add lime to it to neutralize the acidity. In the future, when the soil is well cultivated, a neutral reaction will be maintained in it by itself and the gardener will not have to worry about acidity. But at first this question needs to be solved with the help of lime fertilizers, among which the most common are ground limestone, ground chalk, slaked lime and dolomite flour. The first three contain calcium carbonate salts, and dolomite flour contains calcium and magnesium salts. Liming is usually carried out in autumn before the main digging. The amount of lime material depends on the mechanical composition of the soil and on the pH value. Because vegetable crops quite sensitive to acidity and react poorly to both too acidic and too alkaline reactions, it is important not to miss and add a dose of lime that is appropriate for your soil. In our opinion, it is safer to stick to lower doses, since the subsequent application of manure or compost will, in turn, help to neutralize excess acidity.
Below we provide a table taken from the ʼʼHandbook of a vegetable growerʼʼ (Minsk, 1984).
If you yourself will determine the pH in the water extract using indicator paper, then keep in mind that the first two columns of Table 1 will correspond to the strongly acid reaction you obtained. 1 (рН=4.5^5.0), medium-acid - the third column (рН=5.1-^-5.5), slightly acidic - the fourth column (рН=5.6-nb.0), close to neutral - fifth column (рН=6.1 -Н>.5). If liming is carried out with slaked lime, then the doses are reduced by 1.35 times. On highly acidic soil, it is recommended that a high dose of lime be applied not immediately, but in parts, so that soil organisms can gradually adapt to changing conditions.
Table 1 Approximate norms of lime for vegetable crops based on the mechanical composition and acidity of the soil
Wood ash is alkaline and should also be used to neutralize the soil. It is recommended to apply it every 2-3 years no more than 1.25 kg per 10 m 2.
Further, it would be desirable to make an analysis for the content of organic matter. Earlier we said that the critical value is 2% of the weight of the soil; this is an extremely important condition for stable soil fertility. At a lower content, certain measures are necessary: organic fertilizer, green manure - more on this will be discussed below. An analysis of the most important plant nutrients - nitrogen, phosphorus, potassium - will show you which substances are deficient in your soil. Nitrogen deficiency is compensated by the application of organic fertilizers. Quite often there is a deficiency of phosphorus. In this case, the introduction of superphosphate is allowed in the first year, which will help to quickly satisfy the need of plants for phosphorus, but at the same time ground phosphorite is also applied with the expectation of its long-term effect. It is possible to estimate the content of nutrients according to the results of chemical analyzes only on soils poor in organic matter. Soils that are annually fertilized with organic fertilizers do not need soluble mineral fertilizers, since they contain a significant part of the nutrients in their humus.
SOIL SECTION - concept and types. Classification and features of the category "SOIL SECTION" 2017, 2018.
to the Republican meeting of young ecologists in the competition "Young Soil Scientist"
SOIL STUDIES
What do soil scientists study?
Soil science, despite the importance of soil in our life, was recognized as an independent branch of natural science only at the end of the 19th century among the natural sciences. The works of the great Russian explorer Vasily Vasilyevich Dokuchaev showed that this is another shell of the earth's surface, separate from the atmosphere, hydrosphere and lithosphere.
Soil with fertility 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 factor".
Soil is formed from rocks that come to the surface of the earth under the influence of various factors. Under the influence of wind, atmospheric moisture, due to climate change and temperature fluctuations, rocks, such as granite, gradually crack. Microorganisms appear on them, feeding mainly on carbon and nitrogen of the atmosphere and mineral compounds, which they receive from the rock. Microorganisms destroy it with their secretions, and the chemical composition of 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 outside the settlement and dig a hole in the forest or meadow (hereinafter referred to as the soil profile) (Fig. 1), then you can find a series of layers (soil horizons) that differ from each other in color, density, moisture and other signs.
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Rice. 2 - Profiles of tundra, podzolic and sod-podzolic soils.
Soil horizons are formed at the same time, as a result of the combined action of the factors of soil formation listed above, 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 elucidate the main patterns of origin, functioning, geographical distribution, evolution of soils and soil cover. Huge scientific material was obtained, revealing the differences between soils and other environments. Similar studies have been actively conducted and continue to be carried out in our country. At present, almost the entire territory of Russia has been characterized in terms of soil cover. The main soil types that are 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 their depth. Then it is necessary to describe the soil profile in detail, progressively noting from top to bottom the specific features of the selected horizons.If possible, you need to make sketches and photographs of the profile opened by the cut.
Methodology for describing soil profiles
On the front (front) wall of the soil section illuminated by the sun, one can easily distinguish soil horizons that replace each other in the vertical direction and differ in color, structure, mechanical composition, moisture content, and other features. 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 symbols for genetic soil horizons are currently in use:
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 the litter of plants at various stages of decomposition - from fresh to completely decomposed. |
Horizon A | humic, 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 due to the composition and amount of humus. |
Horizon E | Podzolic or solod, eluvial, formed under the influence of acid or alkali destruction of the mineral part. This is a highly clarified, structureless or stratified loose horizon, depleted in humus and other compounds, as well as in silt particles due to their washing 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 washing out from the overlying horizons. In soils where there is no significant movement of substances in the soil column, horizon B is a transitional layer to the parent rock, is characterized by a gradual weakening of the processes of humus accumulation, decomposition of primary minerals and can be divided into B1 - a horizon with a predominance of humus color, B2 - a horizon of weaker, uneven humus coloration, B3 - the 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 carbonate segregations in the form of deposits, veinlets, pseudomycelium, white-eye, and rare concretions. |
Horizon G | Gley, characteristic of soils with constant excess moisture, which causes restoration processes in the soil and gives the horizon character traits- gray, grayish-blue or dirty green color, the presence of rusty and ocher spots, fusion, viscosity, etc. |
Horizon C | Maternal (soil-forming) rock, from which this soil was formed, not affected by specific processes of soil formation (humus accumulation, eluviation, etc.). |
Horizon D | An underlying rock that lies below the parent (soil-forming) rock and differs from it in its properties (mainly in lithology). |
In addition to the above horizons, there is also whole line independent and transitional horizons, but more about them can be found in the literature.
Method of determinationbasic morphological properties of soils
When describing the morphological features of horizons, soil color, moisture content, granulometric composition, structure, soil composition, new formations, and inclusions are indicated.
soil coloring - one of the main external signs. The color of the soil makes it possible 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, smears and "mold" causes the presence of lime in the soil.
Granulometric composition of the soil - the most important characteristic of the soil (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. The granulometric composition of soils determines the conditions for tillage, the timing of field work, the norms of mineral, organic fertilizers and doses of lime, drainage parameters, the selection of crops, etc.
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Rice. 5. Determining the type of soil.
Table number 2
Determining the type of soil by the nature of cord formation
soil type | The nature of cord formation |
The soil is sandy | The ball is not formed. The sample completely disintegrates in the hand. |
The soil is sandy | The resulting ball has a rough surface. When you try to roll it into a cord, it immediately breaks into pieces. |
The soil is light loamy | The cord, when you try to pick it up from the palm of your hand, breaks into slices. |
Medium loamy | When the cord is rolled into a ring, it breaks. |
The soil is heavy loamy | When folding the cord into a ring, it cracks |
clay soil | When the cord is rolled into a ring, no cracks are formed |
Soil structure is the ability to disintegrate into separate particles. To determine the structure, it is necessary to cut a sample with a shovel, toss it 1-2 times on a shovel and consider the shape of the structural units into which the soil sample broke up. According to the shape of the aggregates, three types of soil structure are distinguished (cubic, slab-like, and prismatic), 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 withstand the eroding action of water). It is enough to place several structural agents in a glass of water. If, with light shaking, they quickly collapse, then this indicates their fragility. And if they retain their shape, then, therefore, the soil has a water-resistant structure.
Density (addition) - the nature of the fit of soil particles to each other and the degree of their porosity - is closely dependent on the particle size distribution, humus content, abundance of roots, structural state, moisture content and varies greatly over the horizons (Table 3).
Table No. 3
Determining the type of soil composition
Types of addition | Characteristic |
crumbly | A shovel or knife is easily immersed in the soil, the soil crumbles into separate aggregates without effort |
The knife with little effort enters to a depth of 3-5 cm, the soil is easily broken by hands |
|
With great effort, the knife enters to a depth of 3-5 cm. |
|
Very dense | A shovel or knife, with a strong blow, enters the soil to a depth of no more than 1 cm. |
Humidity - an important morphological feature: it affects the color, structure, density of soils. In the field, 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 the degree of soil moisture
Degree of humidity | Characteristic |
The soil is dusty, does not cool the hand. |
|
The soil is not dusty, it cools the hand, and when it dries, it brightens a little. |
|
The soil sticks together into a lump when squeezing the hand, when it dries, it brightens and retains its shape, a wet mark remains on the hand, filter paper becomes wet when applied to a lump of soil. |
|
The soil, when squeezed in the hand, sticks to it, wets the hand, but the water does not ooze through the fingers. |
|
The soil, when squeezed in the hand, strongly wets the hand, water does not ooze on the fingers or water oozes from the horizon. |
All results obtained in the course of 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 under laboratory conditions. To do this, at the end of the morphological description of the soil profile, samples are taken from the identified horizons for analysis. Usually selected gr. soil. Sampling is carried out in soil bags or kraft bags, must be labeled (information about the horizon is applied to a sheet of paper and placed 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 room.
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 burrowing vertebrates. Among this soil animal world, we can distinguish between 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 meet outside the soil (most animals). The latter are associated both with terrestrial fauna, in particular, with grass cover, shrubs and trees, and partly with water (some aquatic beetles, like swimmers and water lovers, pupate in the ground; some representatives of these families burrow into the ground for wintering, do the same and tritons). The population of the soil, undoubtedly, features of adaptation to the underground way of life (such are the digging forelimbs of the mole, etc.). But in many animals we will not find any features in this respect (various caterpillars, many beetle larvae, such as ground beetles, etc.). Living in the soil, many animals have a noticeable impact on their environment. Firstly, they can influence the mechanical structure of the soil, loosening and processing it, and secondly, due to their vital activity, they change it chemically. In addition, many enter into relationships with the underground parts of plants that serve them as food (carrot 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
Manual disassembly method soil samples(Gilyarov, 1975). This is a direct counting method that allows the researcher to obtain figures showing the number of counted objects per unit of soil surface area, or per unit of soil volume. 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 extract material:
1. Digging more or less deep holes.
2. Loosening or digging the surface layers of the soil with a shovel.
3. Digging up individual plants to detect insects on the roots.
4. Inspection of the soil surface to detect nests of animals settling in the soil.
5. Inspection of soil layers on soil sections, slopes near river banks, in ravines, in artificial structures (pits, ditches, etc.).
The sampling process is as follows. First, the area of the sample in the area under study is marked by hammering pegs in the corners of the measured square, pulling a string between them. Then, from the boundaries of the measured area, litter or litter (if samples are taken in the forest) or dry loose earth of the surface layer (on fallows) is raked in different directions. 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 residues are removed from the sample area on oilcloth by hand, which are carefully sorted by hand, taking into account and collecting all the animals found at the same time, and the grass is pulled out, which facilitates further disassembly from the upper soil layer. Invertebrates encountered on the soil surface are fixed and recorded separately from those encountered in the soil itself. Then (after removing the disassembled plant residues), they begin to dig the soil from the sample area with a shovel. Small portions of earth thrown out onto an oilcloth (or other bedding) laid out next to the sample are carefully sorted out by hand, and larger clods have to be broken, and the plexus of roots and turf must be torn. Portion after portion of the entire earth from the layer being disassembled is rubbed on weight between the palms, carefully watching all the earth falling on the oilcloth and collecting falling and easily detectable animals.
Animals are collected separately from each sample and layer. As a fixative for worms, 4% formalin can be used, 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 gives a detailed description of the site and the sampling site.
If it is necessary to make a quantitative account of the fauna, then it is necessary to prepare statements "Fauna of the soil" and enter the relevant data into them during excavations (Appendix).
Application
Diary form for describing the soil section
Month 200
1. R. No. __________________
2. Oblast ____________________________ District __________________________
3. Item _______________________________________________________________
_______________________________________________________________________
4. General relief ________________________________________________________
_______________________________________________________________________
5. Microrelief _____________________________________________________________
_______________________________________________________________________
6. The position of the section relative to the relief and exposure _____________________
_______________________________________________________________________
7. Vegetation cover __________________________________________________
_______________________________________________________________________
8. The site and its cultural condition ______________________________________
9. Signs of waterlogging, salinity and other characteristic features _________________________________________________________________________
_______________________________________________________________________
10. Depth and nature of boiling from HCl (weak / violently) _______________________
_______________________________________________________________________
11. Groundwater level _______________________________________
12. Parent and underlying rock ___________________________________
_______________________________________________________________________
13. Soil name _____________________________________________________
Drawing outline soil section | horizon and power in cm | Description of the horizon |
Application
soil fauna
Date ______________________ Time ______________________________
Place __________________________________________________________
The nature of the area ______________________________________________
Type of vegetation ______________________________________________
The size of the pit _________________________________________________
found animals | 1st layer | 2nd layer | 3rd layer | 4th layer | Notes |
The following is a list of the most commonly found animals in the soil and available for study.
Nematodes (roundworms)
Ticks (red tick)
Centipedes
Orthoptera (Earwig)
Proboscis (larvae of cicadas, aphids)
Coleoptera (larvae of the eastern beetle, nutcracker; ground beetle)
Lepidoptera (pupa and larvae)
· Hymenoptera (nests of sand wasps, bumblebees, ants).
Bulatov Andrey Rushanovich
Research work 22 p. , 8 sources, 5 applications.
The purpose of this work: explore and describe the soil section
Tasks:
- prepare and take soil samples
- define soil horizons
- determine the mechanical composition of the soil
- study the morphological features of the soil
- determine the acidity of the soil using biological indication.
- determine soil salinity by chemical methods
Object of study: soil from the Medvedevo landfill
Subject of study: soil properties
Study:
conduct a biometric study of the influence of the papillary pattern of the fingers on the predisposition to weightlifting
As a result of the study, a soil section was described, the type of soil on the territory of the Medvedevo landfill was determined: gray forest: moist, dark gray with iron oxide impurities in the second layer, loose texture, finely nutty and nutty, slightly acidic soil, contains thousandths of percent chloride - ions.
Morphological features that determine the soil in the field:
1) soil profile structure: 4 layers (chernozem, washout zone, washout zone, parent rock)
2) color (color) of the soil: dark gray
3) the degree of moisture (as well as the level of groundwater or perched): wet
4) mechanical composition: medium loam
5) structure: structural, finely nutty
6) addition: loose, loose, dense
7) neoplasms: specks and veins filled with a crystalline substance, which indicates the presence of easily soluble salts (chlorides) in the soil.
Soil horizons are determined.
The mechanical composition of the soil was determined by the method of rolling moistened soil:
1 layer - medium loam
2 layer - medium loam
3 layer - heavy loam
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Introduction 5
Study:
- Soil preparation 5
- Description of soil section 7
- Definition of soil horizons 8
- Determination of the mechanical composition of the soil 9
- Determination of soil moisture 9
- Determination of soil color 9
- Determination of soil structure 10
- Determination of soil density and composition 12
- Determination of soil acidity 12
- Determination of soil salinity 13
- Detection of carbonates 13
- Determination of chloride - ions 13
- Detection of sulfate - ions 13
- Biological indication of soil 14
Conclusion 14
Bibliography 16
Annex 17
Soil - a very thin surface layer of the earth's land - is the main source and basis for the production of almost all food and raw materials for many industries.
The soil is an independent natural body and at the same time a means of production in agriculture and forestry. An essential and inalienable quality of the soil is its fertility. Soil fertility is called its ability to provide plants with the necessary amount of nutrients, water and air. It develops in the course of the soil-forming process and human impact on the soil. Almost everything we eat comes from the soil. It also accumulates and purifies fresh water, providing plant nutrition. Soil-vegetable serves as a regulator of the water balance of the land, absorbing and retaining a huge amount of atmospheric moisture, a universal biological absorber and neutralizer of pollution. natural and wastewater, being filtered through the soil, they are cleared of sand turbidity and some dissolved substances. The organic matter of the waters is decomposed by soil microbes.
The earth is a gift of nature and is not a product of human labor. It turns into a product of labor only when a person processes it, irrigates, drains, and fertilizes it. Land is an indispensable means of production, limited in space, and with proper use does not become obsolete morally and physically.
The study was conducted from July 19-23, 2014 at the Medvedevskoe settlement test site.
Target: explore and describe the soil section
Tasks:
- prepare and take soil samples
- define soil horizons
- determine the mechanical composition of the soil
- study the morphological features of the soil
- determine the acidity of the soil using biological indication.
- determine soil salinity by chemical methods
Object of study: soil from the Medvedevo landfill
Subject of study: soil properties
Study:
- Soil section preparation (Appendix 1, page 13)
To describe soils, study their morphological features, establish boundaries between different soils, and take samples for analysis, special pits are laid, which are calledsoil cuts. They are of three types; full (basic) cuts, half-holes and pits.
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 needed lay in the most characteristic location of the surveyed area. Soil cuts should not be laid near roads, next to ditches, on microrelief elements atypical for the given territory (depressions, bumps).
In the selected area of the terrain, they dig a soil section so that its three walls are sheer , and the fourth descended stairs
The front, front, wall of the incision, intended for description, should befacing the sun.
When digging a cut, the soil must be thrown away onlyon the sidesand in no case on the front wall, which can lead to its pollution, destruction of the upper horizons, changes in their thickness, etc.
Full, or basic, incisionslaid to such a depth as to open 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 purpose 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 holes, or control cuts, are laid to 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 effervescence from hydrochloric acid and the occurrence of salts, the degree of leaching, podzolization, alkalinity, and other features, as well as to determine the area of distribution of soils characterized by complete sections. If, when describing the half-pit, new signs were found that were not noted earlier, then a full section should be made at this place.
Pit marks, or small superficial cuts, with a depth of less than 75 cm, 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 supposed to change to another.
Descriptions of soil cuts, hollows and pits are entered in diary , in which, in addition, information about the relief, vegetation, groundwater, the results of field studies of the physical, chemical and other properties of the soil should be recorded. A sample form of a field soil diary is given below. It is necessary to pay special attention to these signs and study them most carefully.
- Description of the soil section
July_ month 2014
1. Cut #1
2. Region: Tyumen region District _Golyshmanovsky
3. Village council, collective farm, state farm __Medvedevo
4. Point polygon "Medvedevo"
5. The general relief is hilly
6. Microrelief _river floodplain
7. The position of the section relative to the relief and exposure _______________________________________
8. Land cover: grassy
9. Land and its cultural state: Medvedevskiy landfill, forest area
10. Signs of waterlogging, salinity and other characteristic features _____________________
11. Depth and character of HCl effervescence: no effervescence
12. Ground water level: 2 - 2.5 m
13. Parent and bedrock: Soil types are related to the work of the river
14. Soil name: gray forest
The main morphological features that determine the soil in the field:
We took 3 soil samples.
- Definition of soil horizons
On the front wall of the soil section illuminated by the sun, we identified soil horizons that replace each other in the vertical direction and differ in color, structure, mechanical composition, moisture content, and other features.
Horizon A: humic, 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 due to the composition and amount of humus. The thickness of the humus horizon varies from a few centimeters to 1.5 m or more.
Horizon B - located under the eluvial horizon, has an illuvial character. It is brown, ocher-brown, reddish-brown, characterized by the accumulation of clay, oxides of iron, aluminum and other colloidal substances due to their washing out from the overlying horizons. In a soil-compacted and weighted, well-structured horizon, where there is no significant movement of substances in the soil stratum, horizon B is a transitional layer to the parent rock, characterized by a gradual weakening of the processes of humus accumulation, decomposition of primary minerals and can be divided into IN 1 - horizon with a predominance of humus color, AT 2 - subhorizon of weaker and uneven humus coloration and AT 3 - subhorizon of the end of humus streaks.
Horizon B to
Horizon B - located under the eluvial horizon, 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 washing out from the overlying horizons.
Horizon B to - the horizon of maximum accumulation of carbonates, usually located in the middle or lower part of the profile and is characterized by visible secondary carbonate segregations in the form of deposits, veinlets, pseudomycelium, white-eye, and rare nodules.
Horizon C - the parent (soil-forming) rock from which the given soil was formed, not affected by specific processes of soil formation (humus accumulation, eluviation, etc.).
- Determination of the mechanical composition of the soil
We determined the mechanical composition of the soil by rolling moistened soil.
A small amount of soil was mixed with water to the consistency of a thick, viscous mass. This mass was rolled into a ball with a diameter of 1–2 cm. The ball was rolled into a cord 3 mm long, which was bent into a ring with a diameter of 3 cm.(appendix 2, page 14)
1 layer - medium loam
2 layer - medium loam
3 layer - heavy loam
5. Determination of soil moisture
Moisture is not a consistent feature of any soil or soil horizon. It depends on many factors: meteorological conditions, groundwater level, mechanical composition of the soil, nature of vegetation, etc. For example, with the same moisture content in the soil, sandy (light) horizons will appear wetter than clay (heavy).
The degree of humidity affects the severity others morphological features of the soil, which must be taken into account when describing the soil section. For example, wet soil is darker in color than dry soil. In addition, the degree of moisture affects the constitution, soil structure, etc.
In field research, one should distinguishfive degrees of humidity soils: 1) dry the soil is dusty, the presence of moisture in it is not felt to the touch, it does not cool the hand; soil moisture is close to hygroscopic (humidity in the air-dry state); 2) dampish the soil cools the hand, does not dust, brightens a little when it dries; 3) wet soil - moisture is clearly felt to the touch; the soil moistens the filter paper, when it dries it becomes much lighter and retains the shape given to the soil when squeezed by hand; 4) raw the soil, when squeezed in the hand, turns into a pasty mass, and the water wets the hand, but does not ooze between the fingers; 5) wet soil - when squeezed in the hand, water is released from the soil, which oozes between the fingers; soil mass shows fluidity.
The samples we took are moist soil.
6. Determination of soil color
Soil color is one of the most important external properties it, the most accessible for observation and widely used in soil science for appropriation titles soils (chernozem, krasnozem, zheltozem, serozem, etc.).
Soil color is directly related to itschemical composition, conditions of soil formation, humidity.
The color of the horizon depends on the presence in the soil of one or another amount of coloring substances. Upper horizons painted humus V dark colors(gray and brown). The more humus the soil contains, the darker the horizon is colored. Availabilityiron and manganesegives the soil brown, ocher, red tones. Whitish, white tones suggest the presence of processes podzolization (washout of decomposition products of the mineral part of the soil),malting, salinization, carbonation, i.e., the presence of silica, kaolin, calcium and magnesium carbonate, gypsum and other salts in the soil.
Soils are rarely painted in any one pure color. Usually the color of the soil is quite complex and consists of several colors (for example, gray-brown, whitish-gray, reddish-brown, etc.), with the name of the predominant color placed last.
Thus, to determine the color of the soil horizon, it is necessary: a) to establish the predominant color; b) determine the saturation of this color (dark, light-colored); c) note the shades of the primary color. For example, brownish light gray, brownish brown, light, grayish fawn, etc.).
The soil studied by us is dark gray in color, in the second layer there is an admixture of brown color, which is associated with the presence of iron oxide.
7. Determination of soil structure
Soil structure is an important and characteristic feature that is of great importance in determining the genetic and agricultural characteristics of soils. Soil structure refers to its ability to naturally break down intostructural units and aggregates, consisting of mechanical soil elements glued together with humus and silty particles. The form of structural units depends on the properties of the soil itself.
Morphological types of soil mass structures are well developed by S. A. Zakharov, whose classification of structural units we present (Fig. 4, Table 4).
Rice. 4. (according to S. A. Zakharov)
I type : 1) coarse-lumpy, 2) medium-lumpy, 3) fine-lumpy, 4) dusty, 5) coarse-nutty, 6) nutty, 7) fine-nutty, 8) coarse-grained, 9) granular, 10) powdery.
II type : 11) columnar, 12) columnar, 13) coarse prismatic, 14) prismatic, 15) fine prismatic, 16) fine prismatic.
III type : 17) slate, 18) lamellar, 19) foliate, 20) coarse-scaly, 21) fine-scaly
Table 4. Classification of structural units of soils (S. A. Zakharov, 1929)
Types | childbirth | Kinds | Dimensions |
I. Cuboid (uniform development of the structure along three mutually perpendicular axes) | A. Faces and edges are poorly expressed, aggregates are mostly complex and poorly designed: 1) lumpy | Large-blocky | Cube edge |
Small-blocky | 10-5 cm |
||
2) lumpy | coarse lumpy | 5-3 cm |
|
Lumpy | 3-1 cm |
||
Finely lumpy | 1-0.5 cm |
||
3) dusty | dusty | ||
B. The edges and edges are well defined; the aggregates are clearly defined: 4) nutty | coarse-nutty | >10 mm |
|
Nutty | 10-7 mm |
||
small nutty | 7-5 mm |
||
5) grainy | Coarse-grained | 5-3 mm |
|
Grainy (grainy) | 3-1 mm |
||
Fine-grained (powdery) | 1-0.5mm |
||
II. prismatic (structure development mainly along the vertical axis) | A. The faces and edges are poorly expressed, the aggregates are complex and poorly designed: 6) columnar | Large columnar | Diameter |
Pillar-shaped | 5-3 cm |
||
small columnar | |||
B. Edges and edges are well defined: 7) columnar | Large columnar | >5 cm |
|
columnar | 5-3 cm |
||
Small-columnar | |||
Large prismatic | >5 cm |
||
8) prismatic | Prismatic | 5-3 cm |
|
fine prismatic | 3-1 cm |
||
Pencil | |||
III. plate-shaped (development of the structure along the horizontal axes) | 9) tiled | slate | Thickness |
tiled | 5-3 mm |
||
lamellar | 3-1 mm |
||
leafy | |||
10) scaly | shelly | >3 mm |
|
Rough-scaled | 3-1 mm |
||
small-scaled |
Each type of soil and each genetic horizon is characterized by certain types of soil structures. Humus horizons, for example, are characterized by a granular, lumpy-granular, powdery-lumpy structure; for eluvial horizons - platy, leafy, scaly, lamellar; for illuvial - columnar, prismatic, nutty, blocky, etc.
The studied soil sample has the following structure:
- finely nutty
- finely nutty
- nutty
- Determination of the density and composition of the soil
The composition of the soil is an external expression of the degree and nature of its density and porosity (the size and shape of air pores and cavities)
There are 4 degrees of soil density in a dry state:
- very dense - the soil does not lend itself to the action of a shovel
- dense addition - a shovel or knife hardly enters the soil to a depth of 4 - 5 cm, and the soil is difficult to break with hands (alkaline soils)
- loose structure - a shovel or knife easily enters the soil, the soil is well structured, but structural aggregates are relatively little cemented among themselves (loamy soils)
- crumbly structure - the soil has friability, individual particles are not cemented together, characteristic of sandy loamy and structureless, pulverized arable soil horizons.
This soil sample is characterized by a loose texture.
- Determination of soil acidity
We determined soil acidity using universal litmus paper.
They took 30 g of soil, 150 g of water (distilled), let it stand for 20 minutes, brought in an indicator paper, the color of the litmus paper turned yellow-brown, the soil was slightly acidic.(Appendix 3, page 15)
- Determination of soil salinity (Appendix 4, pp. 16 - 17)
An excess of salts dissolved in the soil (salinity) reduces its fertility. These salts are: chlorides of sodium, magnesium, calcium, carbonate and sodium sulfate.
For the experiment, a soil extract was prepared. To do this, they took 100 g of soil and 250 g of water, stood for 2 hours, shaking occasionally. The resulting suspension is defended and filtered.
10.1. Detection of carbonates
First aid. The affected area of the skin is washed with a strongly sliding jet cold water within 10 - 15 min. after washing, a gauze bandage or a cotton swab soaked in an aqueous 2% solution of baking soda is applied to the burned area. In 10 minutes. the bandage is removed, the skin is washed, moisture is carefully removed with filter paper or soft
tissue and smeared with glycerin to reduce pain. If drops of acid get into the eyes, they are washed with running water for 15 minutes. and after that - with a 2% aqueous solution of baking soda. After that, the victim is sent to a medical facility.
No visible signs of reaction were observed, which means that the soil does not contain carbonate - an ion.
10.2. Determination of the presence of chlorides in the soil
NaCl + AgNO 3 \u003d AgCl + NaNO 3
10.3 Detection of sulfate - ions in the soil
Safety regulations for working with barium salts
Barium chloride BaCl 2 is toxic, when its dust is inhaled, acute inflammation of the lungs and bronchi can develop; if the drug is ingested through the digestive tract, acute and chronic poisoning can occur. Toxic doses are small: 0.2-0.5 g BaCl 2 cause severe poisoning, 0.8-0.9 g - death.
It is necessary to work with barium compounds in such a way as to prevent the appearance of dust from them and its entry into the mouth. After finishing work, wash your hands thoroughly with soap and running water.
First aid - gastric lavage with a 1% solution of sodium sulfate or magnesium sulfate to bind barium ions Ba 2+ to barium sulfate. After that, you need to take inside a solution of sodium or magnesium sulfate (20 parts by weight of salt per 150 parts by weight of water), one tablespoon every 5 minutes, after 30 minutes. - induce vomiting to remove barium sulfate.
- Soil biological indication
We determined the acidity of the soil by the plants that grow in the area.(Annex 5, page 18). On this site grow: cuff, caustic ranunculus - the soil is slightly acidic.
Conclusion
As a result of the study, we described the soil section, determined the type of soil on the territory of the Medvedevo landfill: gray forest: moist, dark gray with iron oxide impurities in the second layer, loose texture, finely nutty and nutty, slightly acidic soil, contains thousandths of percent chloride - ions.
Morphological features that determine the soil in the field:
1) soil profile structure: 4 layers (chernozem, washout zone, washout zone, parent rock)
2) color (color) of the soil: dark gray
3) the degree of moisture (as well as the level of groundwater or perched): wet
4) mechanical composition: medium loam
5) structure: structural, finely nutty
6) addition: loose, loose, dense
7) neoplasms: specks and veins filled with a crystalline substance, which indicates the presence of easily soluble salts (chlorides) in the soil.
Soil horizons were determined.
The mechanical composition of the soil was determined by the method of rolling moistened soil:
1 layer - medium loam
2 layer - medium loam
3 layer - heavy loam
The work used "Methods of research activities in ecology" Tyumen 2013
Bibliography
- Ganzhara N.F. Soil science.-M.: Agrokonsalt, 2001. - 392 p.
- Dyakovich S.V. Soil as an object of study in chemistry lessons. Moscow: "Enlightenment" 1985.
- Kaurichev I.S., Panov N.P. etc. Soil science. – M.: Agropromizdat, 1999.- 719 p.
- Postnikova T.F. "Ecological monitoring of the soil" Internet portal "Research activities of schoolchildren"
- Serdobolsky I.P. Agrochemical methods of soil research. M., 2002.
- Sidorov A.M. "Assessment of the ecological state of the soil" "Ecology", M., Drofa, 2004
- School environmental monitoring. Teaching aid / ed. T. Ya. Ashikhmina - M .: AGAR, 2000
8. "Methods of research activities in ecology" Tyumen 2013
Types and purpose of soil sections. The method of direct study of soils in the field is based almost entirely on elucidating the morphological characteristics of soils.
The study of soils is carried out mainly along soil sections, which are a specially dug hole of one or another depth. By appointment, the cuts are basic, semi-pits, or control, and pits.
The main sections are made in places that are most typical for the study area, both in terms of topography and vegetation. In the study of arable plots, they are guided primarily by the terrain, and in the study of virgin lands, in addition, they take into account the nature of the vegetation.
The incisions are usually made to full depth (1.5-2 m and deeper) so that the parent rock can also be discovered and studied. In cases where groundwater occurs close to the surface, the main sections can be up to 1 meter deep or even less. From these sections, soil samples are taken 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.
Control cuts are made much more than the main ones. Samples are sometimes taken from them as well. The soil in the control sections is described more briefly than in the main ones.
Diggings serve to establish boundaries between soil varieties and to highlight the contours of these varieties. Pigs are made to a depth of 30 to 50-70 cm. The soil in the pits is not described, only its name is recorded.
Location and conduct of soil sections. Work on the study of soils in the field begins with the choice of a place for a soil pit. This is very important, since the correctness of the conclusion about the soil of the whole area depends on the correct choice of the place. Before choosing a place for the cut, you need to make one or more digs.
Soil sections should not be located near roads, near the sides of ditches, in microdepressions that are atypical for a given area, etc.
When choosing a site, they are guided mainly by the relief of the site, then by the vegetation and 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 distributed on all relief elements: on watersheds, at the beginning, in the middle and at the end of any slope, on a plain, in a river valley, etc. types, species and varieties in the study area.
It is quite clear that the density of 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 more rugged the terrain, the more variegated and 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 total number cuts per unit area are much smaller.
So, on a small area under study, 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 river terrace), then it is necessary to make several main cuts and digs on it. The same will be required for the characterization of 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, the territories are conditionally 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 a high complexity of soils; 3) steppe and desert-steppe regions with soil complexes occupying 40-60%; 4) floodplains, floodplains, river deltas with a simple cover, with the presence of less than 20% of forested and bushy areas; 5) mountain and foothill lightly forested areas.
3) floodplains, floodplains, river deltas with a complex, heterogeneous soil cover (salinization, waterlogging, 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, consequently, the more soil cuts must be made in a certain area, and vice versa, the smaller the scale, the fewer cuts have to be made in the study area.
The number of soil profiles laid in the study area is determined by the scale of the soil survey and. category of terrain according to the difficulty of carrying out soil research.
To determine 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 digging) is visually tied to the ground, marked with a conventional sign on the soil map, numbered with a serial number, and recorded in the field journal.
After choosing a place for a soil cut, a rectangle is marked on the soil surface with a shovel. Pits should be such that you can freely fall 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 - steps through 30-50 cm, to make it easy to get on and off.
When digging the soil mass, it is recommended to throw it on the long sides of the pit, with the sod or arable layer on one side, and all the underlying land on the other.guiu. When the pit is ready, its front wall is refreshed with a shovel, separate genetic horizons of the soil are established, measured and described.
After describing the soil section and taking samples, the pit must be backfilled. When filling up the cuts, you should first dump the earth thrown out from the depths, and again cover the top with the top layer lying on the opposite side of the pit. This is done in order not to introduce variegation and not spoil the fields, since the lower layers of the soil are usually infertile and require a long time for their cultivation.
Description of soil sections. Morphological features of the soil profile. When describing soils during a field study
are guided by the following most important morphological features of the soil profile.
The structure of the soil (i.e., the division of the soil stratum into genetic horizons).
The thickness of soil horizons and the depth of their occurrence. The thickness of the soil horizons is measured in centimeters plumb, 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 features that are usually used to judge the internal properties of the soil, as well as when dividing the soil stratum into a number of genetic horizons. When describing the soil, the basic color should be defined as simply 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 soil. Therefore, when judging the color of the soil, it is necessary to take into account the degree of its moisture, and the final conclusion about the color of the soil must be given in the air-dry state of the soil samples taken in the field.
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 the inclusions in soils, granite and calcareous boulders are most often found, of neoplasms - compounds of carbonic lime, iron, manganese, gypsum, as well as accumulations of easily soluble salts.
Soil structure by individual horizons. Determining the soil structure in the field is usually done by eye when throwing the earth out of the pit. When describing, the degree of severity of the soil structure should be indicated, for example: distinctly nutty, distinctly granular, indistinct, emerging lamellar structure, well-defined columnar, etc.
The mechanical composition of the soil. Recognition of the mechanical composition of the soil in the field is usually done by eye and touch. So, dry clay is crushed with a finger and eats into the pores of the skin of the fingers, and wet clay is easily kneaded and takes any shape. When rolling a lump between the palms of the hands, the clay gives thin cords. When kneading it with your fingers, the sand is not felt. Heavy loam is rolled into a cord, which, when bent into a ring, forms cracks. Medium and light loams, when wet, roll into a cord; when rubbed between the palms, the sand is clearly felt. Sandy loam in the wet state either does not roll 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 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, mark the level of the latter.
The depth and nature of the distribution of the root system of plants.
The nature of the parent, or parent, rock.
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, digging a hole with a shovel is extremely difficult, it is often necessary to use a soil or peat drill.
When describing soils of the bog type, 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 (weakly decomposed, semi-decomposed and strongly decomposed peat); the mechanical composition of the soil and the degree of its deoxidation, or gleying; depth of occurrence of soil and ground waters; the nature of moisture (ground, atmospheric, mixed).
Soil formation factors. 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, haymaking, forest, swamp, etc.). At the same time, it is very important to note the degree and nature of development, or cultivation, of the described land (for example, newly developed arable land, old arable land, limed, gypsum, drained, irrigated, planted, etc.).
If the cut is made on arable land, the condition of the crops should be noted and their quality should be assessed. Very often on appearance plants can accurately judge the quality of the soil and its fertility.
The best expression of the quality of heterogeneous soils are 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 by cultivated plants, wild flora is an indicator of soil quality.
Of particular importance is the 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 topography.
A thorough study of the natural-historical conditions of soil formation makes it possible to more fully and deeply understand the genesis and originality of the studied soils and to correctly establish those agrotechnical measures with the help of which it is possible to further improve these soils when they are used in agriculture. agriculture. Without a thorough study of the factors of soil formation, it is unthinkable to study soils in nature.
Chemical properties of the soil. In the 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 subsequent laboratory processing of the material collected in the field.
In the field, the presence of carbonates in the soil is usually determined (reaction of the soil solution pH), the content of sulfate, chloride salts and iron ferrous compounds.
The presence of carbonates (CaCO 3, MgCO 3 ) is determined using 5-10% hydrochloric acid. To do this, a hydrochloric acid solution 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 detected sharply; with a low content of carbonates in the soil, effervescence manifests itself weakly, and in the absence of carbonates, it does not manifest itself at all.
Thus, by the nature of the effervescence, one can judge not only the presence of carbonates in the soil, but, to a certain extent, their quantity.
It is most convenient to determine the pH using a universal indicator, which 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.
The content of normal soda (Na 2 CO 3 ) in the soil is detected when a cherry-red color appears after adding a few drops of an alcoholic solution of phenolphthalein to an aqueous extract.
The presence of ferrous oxide in the soil is determined by the blue color of the soil from a drop of fresh red blood salt solution [K 3 Fe( CN) 6 ].
All results of studies of the chemical properties of the soil, as well as the results of a morphological study, 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 are 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 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 out a rectangular piece with a rib length of approximately 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 goals of subsequent laboratory processing (most often 0.5-1 kg).
Each sample is labeled appropriately, wrapped in wrapping paper and tied with twine. The label records the section number, genetic horizon, the depth from which the sample was taken, and the date the sample was taken; under all these data is the signature of the researcher. Without a label, the sample taken is meaningless. The number of samples in the section depends on the number of soil layers (there are usually 4-5 in the main section).
For the agronomic characterization of soils, additional mixed samples from the arable layer are taken from each section. A mixed sample is usually composed of 5 soil samples (each weighing 0.5-1 kg), taken from a small area (100-400 sq. m) around the incision and in the main incision itself. These samples are mixed for
sheet of paper and from the mixture take an average sample weighing about 0.5 kg. One mixed sample should characterize a certain area up to 10 ha.
Mixed samples are mainly used in the study of soils in the soddy-podzolic and northern part of the forest-steppe zone for mass laboratory analyzes necessary for compiling cartograms of soil acidity and the provision of soils with phosphorus and potassium.
In addition to soil individual and mixed samples, soil monoliths with undisturbed structure, composition and structure are sometimes taken during field research. A well-taken soil monolith makes it possible to supplement and verify all morphological observations and records made in the field regarding the color of the soil, its structure, structure, identification of horizons, etc.
The monoliths taken from typical places of the studied area make it possible to visually compare all the distinguishing features of the identified soil varieties. Finally, soil monoliths can serve as a valuable museum and visual educational material for agricultural universities, technical schools and experimental stations.
Monoliths are placed in special wooden boxes of certain sizes. To take a monolith from the main section, the pit is somewhat expanded 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; this column is then put on the frame of the box, to which, after trimming the protruding parts of the soil, the lid is screwed. After that, the column is dug in from the sides and gradually fall off. 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 write the number of the section, the place where the monolith was taken from, and the name of the soil.
When studying swamp 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 also necessary to take samples from the mineral layer of the soil, which lies directly under the peat layer. In this way, a clear idea of the complete 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.
- 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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