The classification of soils is based on the principle of considering the soil as an independent special body of nature, which can be put on a par with minerals, animals and plants. This classification method is based on the properties and characteristics of the origin of soils. The first to divide the soil according to the genetic basis of V. Dokuchaev
The main feature by which division occurs is the type of soil. This classification unit means soils arising under the same conditions and having similar properties and structure.
Among the most well-known to us, the following soil types can be distinguished : podzolic, red soil, chernozem, salt marshes and others. Soil types are further subdivided into subtypes, genera, species and varieties, and categories.
Subtypes reflect the distinctive features of the soil profile. Here plays a role how continental the climate and thermal conditions of this latitudinal zone are. Subtypes are intermediate links between types.
Further separation occurs by genus and soil type. The most common types of soil are ordinary, solonetzic, residual solonetzic, solonchakous, quartz-sand and contact-gley, residual carbonate, residual arid.
Each genus of soils has an additional division into species. The view reflects how pronounced the process of soil formation characteristic of a particular soil type. In turn, several species are distinguished among the species. These are related to one type of soil, the difference of which is only their mechanical composition. These include clay and loamy, sandy and loamy sand. Dividing by category means that the soils have the same type and mechanical composition, but the mother breed is of different origin.
Various properties directly depend on the mechanical composition of the soil.
This value is determined by the ratio of soil particles of different sizes and is expressed as a percentage. Cartilage, pebbles and stones have poor water permeability, formed from rock fragments and primary materials. Sand has the ability to quickly pass water, since it almost consists of only primary minerals. Secondary minerals swell in the water, swelling from water - this phenomenon causes such a property of soils as stickiness and plasticity. The composition of the soil from the sludge includes secondary minerals from clay. They are very swollen in water, then they pass almost neither water nor air.
If the particles are reduced in size, the process of weathering and the subsequent formation of secondary minerals begins - these are hydroxides of iron, aluminum, aluminosilicates and carbonic salts of Ca, K, Mg.
The size of the mechanical elements affects their chemical composition and physical properties. And therefore, knowing the composition of the soil, you can find out what properties it has.
The upper soil horizons and its parent rocks , depending on the mechanical composition, are divided into:
- connected;
- loose.
- heavy;
- medium;
- lungs.
- heavy;
- medium;
- lungs.
Different mechanical composition of the soil, differing in the content of physical clay, affects a property such as plasticity. With its various indicators, the earth can slide into a ball or into a cord. This helps determine the soil texture in the field. Its name, as a rule, reflects its mechanical composition. For example, ordinary chernozem is heavy loamy.
The agronomic properties of soils also depend on their mechanical composition. It is easy to process sandy and sandy, which is why they are called light. Conversely, loamy and clayeys have earned a reputation for being heavy due to difficulties in agronomic processing. However, they contain more nutrients and humus, in contrast to sandy and sandy loam, and therefore are considered more fertile.