Morphological features of soils: the essence of the concept and enumeration of the main

By the morphological characteristics of soils, one can determine their origin and properties, which will indicate the features of their economic use. Consider what this concept means, the main features of soil morphology (the structure of the soil profile in a vertical section, soil color, soil structure and their significance, neoplasms and inclusions).

The essence of the concept

Morphological characteristics of the soil acquires over time as a result of formation. They indicate the genealogical origin of soils, their development, composition, chemical and physical properties.It is also possible to determine some morphological features visually, laboratory studies are required to determine others.

Main morphological features of soils

Among the important features are characteristics: the structure of the soil profile, soil structure, color, inclusions and neoplasms.

Soil profile structure

The soil in its vertical section is heterogeneous and has a layered structure. The profile of a well-developed soil is divided into 3 main layers or horizons, extending from the surface inward and having their own characteristics. Each layer throughout the entire length remains predominantly the same in terms of mechanical, chemical composition, physical properties, structure, color, mineralogical composition, and other features. But all the horizons within the boundaries of the profile are connected and affect one another. The total thickness of the soil, including all layers, can vary from 0.5 to 1.5 m.

Soil layers separate gradually during its formation, but even after the end of formation they do not have a clear boundary, a transitional layer is visible at the confluence. The main layers of the profile: the upper soil, which determines the fertility of the soil, the parent or parent rock and the underlying rock. In the layer from the surface to the parent rock, processes occur that determine the fertility of the soil and its value for agricultural use.

Soil coloring

On this basis, you can determine the horizons of the profile and their boundaries. Coloration is a general term that defines the heterogeneity of the color characteristics of horizons. The color depends on the predominant substances that appeared in the process of soil formation. In accordance with this external characteristic, some types of soils were named: chernozems, krasnozems, serozems, and so on.

The top layer is colored with humus substances, they have a dark color, the more of them, the darker the soil.Brown and red tones give it a high content of iron and manganese. The whitish color of the soil in which the processes of podzolization took place, that is, the processes of leaching of minerals, brackish and carbonate soils have the same color, due to the content of s alts, chalk, gypsum, kaolin, silica in them. A bluish color appears in waterlogged soils that contain minerals with iron oxide. The lower soil horizons are colored according to the composition of the parent rock and the degree of weathering.

The intensity of the color depends on the moisture content of the soil and the degree of illumination, it is determined by the sample of completely dry soil in diffused daylight.

The features of the processes that form the soil are clearly displayed in the shades of soil color. The following 3 groups of substances are considered the most influencing color: humus, lime carbonate, silicic acid and kaolin, as well as iron compounds.Coloring can be uniform and uneven, that is, spotted, striped, speckled.

Soil structure

Soils are composed of individual structural elements, the so-called soil aggregates, which stick together with humus or particles of silt. The size and shape of the aggregates, their strength depend on the processes that occur in the soil.

Moisture and air permeability of the soil, resistance to erosive processes depend on this characteristic. Soil structure is affected by soil microorganisms, plant roots, periodic drying and waterlogging, heating and cooling, freezing and thawing.

Glue particles of soil humus, silt components, hydroxides of iron and aluminum. Sandy soils, where there are few clay particles and humus, have a weak structure. In the process of structuring, plant roots play a large role, which create a lumpy structure.

By shape, structural particles are divided into 3 types: cuboid (approximately the same size in 3 directions, which gives them the appearance of polyhedrons), prismatic (when elongation dominates in height, due to which the structural particles acquire an elongated shape) and platelike (particles acquire a flattened shape). For different types of soils and horizons, a special type of structure is characteristic, for example, granular, lumpy, lamellar, blocky and others.

Changing the conditions of soil formation is reflected in the structure. The strength of the structure of the fertile layer is important for agriculture. Of particular importance is such a characteristic as water resistance, that is, the ability to form individual particles that are not eroded by water. Soils with a water-resistant structure also have mechanical properties and a moisture-air regime that are favorable for the growth of agricultural plants.The less structured soils, the worse their characteristics, they quickly become impervious to air and moisture, swim, and when they dry, they compact and crack.

The weight ratio of particles of different sizes determines the mechanical composition. The size is determined by the specific diameter of the particles, on which their ability to retain moisture depends. The stony fraction with a particle diameter of more than 1 mm cannot retain moisture, therefore it is considered inactive in this regard. Sand holds water poorly, clay dust particles hold moisture best.

Features of the mechanical composition affect the physical properties of the soil: moisture capacity, water permeability, thermal and air conditions, and others. Sandy soils do not have a coherent structure, they crumble even when wet. Dry sandy loamy soils are loose, also have no structure, wet ones easily roll into a ball, but they cannot be pulled into a “cord”.

Loams are dry, wet, plastic and roll freely into a "cord". The thinner it is, the more clay soil. Wet clays are rolled into a thin "cord" that can be rolled into a ring and will not crack. The general name of the soil is given by the analysis of the top layer with a height of 0-25 cm.

New growths and inclusions

So called isolated substances that differ in composition and structure, and which are locally included in the soil of different types. The formation of neoplasms takes place under certain conditions, therefore, by their appearance, one can determine the type of soil-forming processes that took place before or are taking place now. They are an important feature in determining soil classification.

New formations differ in shape, color, mineralogical and chemical composition. They look like spots, veins, plaque, located near the roots of plants or animal passages, they can be concretions or glandular layers.Biological neoplasms are molehills, earthworm passages and their waste products.

Inclusions are foreign bodies, the appearance of which in the soil was not caused by the processes that formed it. These can be rock fragments that are not identical to the parent rock, rubble, large stones, bones and shells of extinct animals, objects left over from human activities. By inclusions, one can understand the origin of the parent rock and establish the age of the soil.

Morphological features of soils help to correctly characterize them, establish their origin, the processes that led to their formation, age and value for economic use. In agricultural terms, morphological features help determine how to improve and ennoble the soil so that it is more suitable for growing plants and becomes more fertile.

Recommended