The structure of the soil is studied in many ways, the choice and application of which is determined by the specific needs of specialists. At the same time, there are universal methods for presenting the characteristics of soil layers, thanks to which scientists can visually get acquainted with the qualities and general features of the land cover of a particular area. For example, there are atomic, aggregate and crystal-molecular levels of representation of the structure, which make it possible to study the soil with one or another detail. The fourth level of representation is formed by soil horizons. Thus, for example, the earth in a section can be reflected, the profile of which was formed by several geological layers for a certain period of time.
Underlying horizons
This is in some way the fundamental and basic layer of soil formation, which acts as the parent rock in terms of the formation of subsequent layers towards the surface. Such layers are heterogeneous and have different characteristics. Specialists single out sandy, clayey, forest litter, as well as combined layers, which are distinguished by a special origin.
It is important to note that parent horizons are calledbasic. They are located at the very bottom, but at the same time they have a serious impact on the upper layers. This is manifested in the ability to form the chemical, mineralogical and mechanical characteristics, as well as the physical qualities of the fertile layers. Accordingly, the forest floor will have more attractive agrotechnical qualities than parent rocks, the mechanical properties of which are determined by sand or clay compositions.
Types of soil structure
Estimation of the characteristics of this or that horizon is impossible without determining its structure. Structurality is understood as a set of aggregates or individual particles capable of randomly disintegrating. That is, it is a property that determines the mechanical state of aggregation of the soil mass. One of the parameters that make it possible to attribute soil horizons to certain structures is the strength of the connection between individual elements and microaggregates of the studied composition. To date, three categories of structures are distinguished in soil science, which differ in particle size, as well as their mutual arrangement. These are prismatic, cuboid and plate structures.
In prismatic soil masses, particles develop mainly along the vertical axis, the cuboid structure implies a uniform distribution of particles in three planes that are perpendicular to each other. Plate-like soils are formed in two axes with a clear shortening in the vertical direction. If the mass does not break up into separate particles, but initiallyis characterized by a loose state, then it is called a separate-particle structureless. This group includes dust and sand. In turn, stony soil can be called structureless massive. Such structures are characterized by the presence of large shapeless blocks.
The value of particle size distribution
If the structure determines the mechanical distribution of individual elements in the soil mass, then granulometric analysis allows us to determine the agronomic properties by assessing the particles directly. For example, experts give a morphological description of the soil profile with fixation of compositional features. Thus, the soil of the desert will be predominantly sandy, and the main task for researchers will be to determine the uniformity of the composition and the predominance of one or another fraction. These analyzes use different methods of measurement, including using metrological equipment.
The meaning of soil color
The color of the soil mass is one of the most striking morphological features that can be used to determine the genetic horizon in the profile. In addition, the earth in a section with an indication of the shades of the layers helps in such studies to fix the boundaries of the horizons. However, the concepts of color and color performance are not equivalent in this case. Color refers to the general characteristic of heterogeneity and spotting. On the other hand, the color of the soil mass indicates the combination of tones, intensity and other chromatic qualities. By the way, many types of soils get their name precisely fromcolor characteristic - these include serozem, krasnozem and chernozem.
The color of the horizon can be heterogeneous and uniform. In the first case, the mass is painted in different tones, while the differences can be traced not only in terms of chromatic features. Color often determines the physical characteristics that stand out along with the shade. For example, the soil of the desert has a uniform color, and its particles become lighter towards the lower layers.
Humus horizons
This is a vast group of soils that are formed through biological decomposition processes. Separate layers of the horizon differ in height, physical qualities, composition of organic elements, etc. At the same time, the hue gravitates more towards the range from gray to black. The characteristic locations of the humus horizon are the steppe and forest-steppe. Actually, the parent forest underlying platforms largely contribute to the formation of the upper layers of this type. In particular, a sod horizon, gray-humus and light-humus horizons are distinguished. Sod layers are more often found in tundra and taiga regions. The humus horizon with humus is also common. It is commonly found in waterlogged landscapes in the south. The light masses of horizons of this type are widely spread in the soils of semi-desert and dry steppe lands, in which a warm arid climate prevails.
Organogenic horizons
This category includes soil horizons in which the content of organic components reaches 30% or more. Most often thisupper layers of the profile. For example, the surface layer is a peat horizon, the height of which is 10 cm. It is formed by decaying vegetation residues, grassy steppe felt, etc. The humus layer is also included in this group. Thanks to it, chernozem soils are formed, which can have both dark brown and black hues. Such layers usually occur under litter-peat layers. There are other subspecies of this horizon, which may include mineral elements. But the main unifying morphological property of all soils included in this complex is the origin based on organic materials. That is, soil formation in this case occurs under the influence of biological decomposition.
Medium soil horizons
A distinctive feature of horizons of this type is the tendency to soil formation processes directly inside the structure without external influence on the masses. A typical representative of this species is the Al-Fehumus horizon. It is characterized by the presence of humic-ferruginous film inclusions on the surface of aggregates or mineral particles. As for color, in this case there are no strict characteristics - a lot depends on the specific composition, which can give the soil both dark and yellowish-light shades. Typically, soil horizons of the middle type are found in sandy or sandy soils. A texture horizon is a good example of this spread. This is a brown mass, which is also distinguished by a multi-order structure andan abundance of multilayer films. However, this horizon can also be found in the predominance of clay soils.
Eluvial horizon
In the profile of the cover lying under the organogenic or humus layers, this is the lightest horizon. It is distinguished by a lightweight granulometric composition and a variety of its constituent elements in terms of physical properties. These horizons include podzolic, humus-eluvial and subeluvial layers. For example, podzolic masses are characterized by a sandy and sandy loamy granulometric base, and in some cases, a structureless cloddy base. This horizon is characterized by the location in the structure of humid and alpha-humus landscapes. By the way, according to some structural characteristics, the illuvial horizon is similar to such layers, although the dominance of brown color still causes pronounced external differences.
Arable horizon
The soils included in the arable horizons are usually surface. But not every surface layer can be classified as fertile soil. A special quality of this horizon is precisely the set of favorable conditions for growing cultivated plants. The composition and agrotechnical characteristics of the fertile layer allow the root system to draw the necessary elements from the soil mass. Chernozem soils create natural conditions for this, but often the necessary characteristics are also increased by special means. For example, through arable-horizon cultivation technologies, fertilization and throughcorrection of the hydrological provision of the earth.
Soil-forming rocks
These are superficial mother layers, which become the basis for the formation of new soils. As a rule, the granulometric set of such rocks consists of mineral components - up to 80%. The exception is perhaps the peat horizon, in which the volume of mineral filling can be within 10%. It is noteworthy that such layers can become an optimal platform for the formation of fertile arable soil with high agronomic properties, but they themselves are not always suitable for cultivation. It can be mountainous or rocky soil, the basis of which is formed by igneous, sedimentary and metamorphic rocks. But, despite the meager characteristics in terms of fertility, such layers become a good base for the development of more attractive covers for agriculture.
Conclusion
Agricultural enterprises and forestry enterprises are the main customers and users of materials in which maps are developed with land sections and indicating the profile of the soil horizon. Such data are required for a more complete understanding and current picture of the characteristics of a natural resource and an idea of the future processes of its development. In particular, soil horizons make it possible to predict what further corrections in the composition of the soil may be. To study such horizons, a wide range of methods supported by modern technical means is used. In addition, those interested inIn such studies, companies themselves often carry out activities aimed at changing the structure and characteristics of certain horizons.
