Soil is a natural body, which was formed by the combined influence of animal and plant organisms, features of the relief, climatic conditions and human industrial activity on the upper part of the earth's crust. Soil is of great importance in nature and human life. Primarily, it serves as a condition for the existence of plants and animals; secondly, without it, a person would simply die of hunger. Thus, the soil, being a product of life, is at the same time a condition for the existence and development of life on our planet.
Soil is the primary means of production in agriculture. All human agricultural activities are based on the use of this resource. Crop production uses this cover as a medium for the development of plants, in livestock breeding - as the basis for livestock food production. For farmers, it serves as an object of application of forces.
The entire agricultural industry is somehow attached to the use of the upper layer of the earth's crust. That is why for its practical application it is necessary to have at least basic knowledge about the properties, composition, formation and distribution of soils.
Soil formation
This process is complex: the mother breed turns into a substance that significantly differs from the original one not only in appearance, but also in its properties. The main condition for successful soil formation is the settlement of living organisms on the mother breed. For the productive reproduction of these organisms, moisture and the type of nutrition that is available for this form of life are necessary. Both of these important components result from weathering of the rock. Soil formation is a continuous process, depending on the interaction of the source rock with the organisms sheltered on it. It proceeds as follows.
The roots of plants that settled on the rock absorb useful substances from it, causing them to rise closer to the surface. After the plant dies, the nutrients contained in them turn into a mobile state. During this process, part of the substances is washed away downward by atmospheric precipitation flows, another part settles in the upper layers of the rock, and new plants absorb the third.
Decomposing, the plants form humus - complex compounds of organic elements. This humus, accumulating in the upper layers of the rock, gives it new properties and colors in a darker color. In parallel with the formation of humus, its decomposition is in progress.
The formation and destruction of humus, as well as the accumulation of nutrients in the upper layers of the soil, is called the biological cycle of substances - the essence of the process of soil formation. It is to this cycle that the barren breed becomes fertile.
Modern science divides the main parent rocks by genesis into several categories. Each of them should be considered separately.
Glacial deposits
The parent rocks of this type include various moraines - the main moraines that were deposited in the places where the glacier used to be, the final ones formed on the very edge of the glacier, and the lateral ones located at the sides of the tongue during the valley type of glaciation.
Whatever kind of moraine they belong to, they will be deposits of the boulder type: sandy loam, sand, clay and loam - in a word, those in the total mass of which boulders are contained in varying amounts. Looseness and a greater number of them are most often found in marginal moraines; clay content is characteristic of the main.
Glacial deposits form special reliefs, especially Drumlin, the terminal sea and others.
Fluvioglacial deposits
These parent rocks are also called water-glacial. They got this name for the reason that they were formed due to the meltwater of glaciers. These deposits most often encircle bottom and end moraines, often overlapping them. This is due to the gradual displacement of the edge of the glaciers. Fluvioglacial formations consist of small-boulder or sand-pebble deposits, which form glacier deltas, lake ridges and other reliefs, ultimately composing sand and pebble fields.
These rocks are characterized by a high grade of material, a clear layering along the oblique, which is natural for deposits of running water.
Soil-forming rocks of this type are adjacent to loam, which has practically flattened bedding. Experts believe that such loamy deposits are formed by small spills of glacial waters. Their structure is dense, viscous, has a yellowish color. For this type, the content of boulders is not characteristic.
Mainly loamy loam is widespread in the watershed, lying on the moraine, from which, almost always, it has a clear demarcation.
Under the same natural conditions, loesslike loams may also occur . The chemical composition of the parent rocks of this type of loam is similar to integumentary, but they differ in carbonate content.
Mostly these deposits give soil of low fertility. The lack of humus, nutrients, low moisture capacity of the material lead to this result. The formation of material in hollows covered with clays, with a gradual swamping of the territory, leads to the formation of parent soil-forming rocks of podzolic soils in these places . At high humidity, they can be marsh-podzolic.
Lake-glacial deposits
In the lowland areas, parent rocks are formed on the basis of the sedimentary material of the lakes that fill the low relief areas near the glaciers. In this case, horizontally layered ribbon clay is predominantly found, but sometimes you can stumble on sands and sandy loam with almost unexpressed horizontal layering.
Alluvial deposits
This group includes sediments that are formed in river valleys, as well as in river mouths with floods. These deposits are clearly layered. The types of parent rocks in the alluvial type of deposits will depend on natural conditions, their composition may be sandy, clay, loamy, etc.
Lake sediments
They are characterized by the absence of ribbon layering inherent in lake-glacial formations. In addition, they are mainly found in lake basins of various periods of formation.
Lake alluvial deposits
As the name implies, this group includes alluvial and lacustrine deposits. These sediments are formed in the lowlands of rivers, woodlands. Especially common in places of frequent and severe floods in the spring. Abundant hydration of rocks during a period of prolonged stagnation of water leads to the appearance of clay deposits of the lake type. The fertile properties of parent rocks of this type are low. In our country, large areas on the territory of Western Siberia, Polesie, etc., are formed precisely by this type of sediment.
Proluvial deposits
Sediments formed by temporary descendants from the mountains are suitable for this definition. The material of these deposits is unsorted, consisting of crushed, pebble and boulder elements. You can meet these rocks at the foot of the mountains: even a small gorge boasts a significant amount of drifts. Merging, these materials form piedmont plain stripes. Very often they are significant - a striking example of this is the strip along Kopetdag.
A distinctive feature, as you can understand, proluvial deposits is the shape of a fan or cone. The composition of the variety is diverse. In the vicinity of the mountain ranges, these are mainly cartilaginous-gravel formations, rather rough. The farther the sediment is removed from the mountains, the finer its structure. At the greatest distance from the foothills of the ridges, the promenade consists of sand and loam.
Eluvial deposits
The parent rocks of this type are formed by weathering rock formations that remain in place.
Based on the composition of the primary rock and the nature of weathering, one can judge what composition and type will be deposits. Under various chemical influences of a natural property, these can be gigantic stone blocks or smooth clay products. Mountain peaks are rich in stony placers, while lowlands with a humid climate are lined with clay deposits.
Eluvium is characterized by a gradual transition in the color of the rocks and a slight difference in the mineralogical composition of the parent deposits from the resulting formations.
Deluvial deposits
The main parent rocks of the mountain types belong to this type of sediment. They are very closely associated with eluvial, being, in fact, eluvium washed away from the hills by rain or meltwater.
Soil-forming rocks of this type have a variety and significant layering. Most often, the layers are parallel to the side of the mountain. Mostly composed of clay particles. The ability to detect large stony debris is very small.
Such deposits are located in places of relief, near mountain ranges or at the foot of hills.
Eluvio-deluvial deposits
The nature of eluvial and deluvial deposits is such that in large areas they are in close proximity. With this arrangement, it is extremely difficult, if not impossible, to distinguish where one type of sediment begins and another ends. Experts decided that parent rocks in this case would be called eluvio-deluvial. They are always located in mountainous regions and areas with hilly terrain.
Aeolian deposits
The formation of such deposits is always associated with the accumulative activity of the wind.
Of course, aeolian sediments are sand deposits that make up the area of deserts and semi-deserts. These formations create recognizable reliefs - dunes. It is for them that the origin of the rock can be accurately attributed to the Aeolian type.
In geographic areas not related to deserts, parent rocks of this type can also be found. These include dunes of various origins: sea, river, and continental. These forms are formed by sand deposits that changed in the past when the climatic conditions were different, or were in the process of re-mowing today - this process often occurs under the influence of human activity. In addition to morphological properties, aeolian deposits are very different from all other types of diagonal stratification and high grading.
Loess
These Quaternary parent rocks form a huge place in our country. The steppes of the south and southeast almost throughout their entire length consist of loess and loesslike loam. These types of rocks have characteristic features: friability, lack of stratification, porosity. Their most important difference is in the high content of magnesium and calcium carbonates.
Marine deposits
Sea parent rocks of Russia are mainly represented in the Caspian lowland. Their formation in this area occurred during the last transgression of the Caspian Sea. These deposits are found here in the form of chocolate plate dense clays, occasionally sand. Often these rocks have strong salinity. In addition, marine deposits are characteristic of the shores of the Arctic Ocean.