Soil cover structure

In nature, there are practically no situations in which a single soil with unchanged spatial properties extends for many kilometers. Obviously, soil differences are due to differences in soil formation factors. Of the classic 5 factors, climate and time do not participate in the formation of NGN. The climate does not change at distances characteristic for SPP and, therefore, exerting not differentiating, but leveling effect on soils. However, it, among other factors, determines the set of possible components of NGN in a given territory. Differences in the duration of soil formation in different parts of the earth’s surface do not directly affect SPP, but in some cases they affect SPP through other factors. Thus, differences in the position of soils in the relief , the effects of living organisms, and heterogeneity of parent rocks affect the formation of heterogeneity of the soil cover.

Friedland made the following rearrangement of these factors in relation to SPP:

• Relief as a redistributor of moisture, soluble matter and heat,
• Relief processes that occur in parallel with soil formation (water erosion , deflation, alluvial and proluvial processes, karst , suffusion ),
• Permafrost phenomena and heterogeneity of snow cover,
• Heterogeneity of parent rocks,
• Groundwater exposure,
• Variegation of vegetation,
• The impact of the animal world,
• Human activities.

In the formation of NGN, random phenomena are of great importance. So, it is possible to accurately predict with known values ​​of these factors what elements will be represented by the soil cover of a particular area, but where these elements will be located is impossible.

The soil cover is continuous (although it is to some extent torn by rock outcrops, water spaces, etc.), however, to describe and study its structure, it is necessary to distinguish some initial structural units with given boundaries. In the Soviet and then Russian schools of soil science, elementary soil area ( EPA ), a soil formation within which there are no soil-geographical boundaries, is considered to be such an initial unit of SPP in the Soviet and then Russian school of soil science. It is formed by soil belonging to any one classification unit of the lowest rank and from all sides is limited by other EPA or non-soil formations. Moreover, the soils of neighboring EPAs can vary at any rank of classification, including at the type level. The soils inside the EPA are not homogeneous, but their properties vary in amplitude, which is allowed by the definitions of the lowest classification units.

The elementary soil range ^[1] is the primary component of the soil cover, which is the area occupied by the soil belonging to one classification unit of the lowest rank.

In foreign literature, there are concepts close to EPA: polyipedon (soil individual) in American, pedotope in German, female in French. Similar concepts are used in landscape science ( epimorpha , elementary landscape , biogeocenosis , etc.) as well as geobotany ( phytocenosis ), the boundaries of these formations and EPA do not always coincide.

Homogeneous and heterogeneous EPA are isolated. In turn, heterogeneous are divided into regularly cyclic or sporadically spotted. Regularly cyclic EPAs are represented by a network of polygons, within each of which the entire amplitude of properties is observed, which is observed for EPAs as a whole (moreover, one EPA can be formed by several classification-different soils, provided that their differences are quantitative rather than qualitative). They usually form under conditions of cracking of the soil with a lack of moisture or frost. The so-called limiting structural elements ( PSE ) are distinguished in the composition of sporadically-spotted EPA.

PSEs are small areas characterized by peculiar soils and limited by the distribution of the factor that determines this originality. Examples of PSE include spots of zoogenically-digged soils, spots of podzolic soils with a thick peat horizon in place of decayed stumps, special soils of anthills , etc. They are exclusively biogenic in nature, which is why they cannot be distinguished as EPA - their boundaries soil, but not soil-geographical. In order to isolate PSE, its soil and the background EPA soil should differ at least at the discharge level.

Soil combinations (PC) are more complex than EPA units of SPP and are formed by alternating in space and to some extent genetically related EPA. They represent the smallest integral sections of the SPP, containing all its components in typical relative positions and relationships.

By the origin, nature of the structure, and the genetic relationship between EPA, six groups of PCs are distinguished:

• The complexes are caused by a microrelief , and therefore the movement of matter between the soils lying on different elements of the relief is two-way and their genetic relationship is mutual. Soils contrast in contrast.
• Spotting is the same as the complexes, but the soils are low contrast.
• Combinations - due to the mesorelief , the exchange of matter between soils on its different elements is one-sided: the overlying soils affect the underlying soils, but not vice versa.
• Variations are the same as combinations, but soils are poorly contrasted.
• Mosaics - due to differences in parent rocks, their components have virtually no genetic relationship with each other, are represented by sharply contrasting soils.
• Tachets - represented by low-contrast soils that do not have a genetic link to each other, are formed under the influence of biological factors, for example, a change in vegetation.

PCs are also divided into two difficulty levels:

• Simple - consist only of EPA and represent the second level of SPP after EPA.
• Complex - consist of simple PCs, sometimes along with separate EPA, this is the third level of NGN. Only combinations, variations, mosaics and tachets can be complex.

There is also another division of PC into background and backgroundless. A background is a combination formed by one holey EPA, into which other EPA intersperse.

Shortcut Methods

For an abbreviated record of soil combinations, usually use the system of soil indices adopted for designation on soil maps, for example, K ₂ ^sn - chestnut solonetzic. In this case, indices written one after another without any signs between them indicate the complex (Lg Lg csk - a complex of meadow , meadow solonchakous soils and salt marshes ), connected by a dot - spotting (P ₁ · P ₁ · P ₃ - spotting is weak, medium and strongly podzolic soils), connected by a plus - combination (P + Pb + B - a combination of podzolic, marsh-podzolic and marsh soils), connected by a minus - variation (Pr-Pp-Pz - variation of fluttering, semi-fixed and fixed sands), connected multiplication sign - mosaic (Dk x Pdb x VGP - mosaic and rendzina , podburs and rocks outputs), dividing - tachets ^(Tm _hBD: T ⁱⁿ _hBD - tachets typical and leached mountain brown soils). Brackets are used to indicate complex combinations, for example (Ch ^t · Ch ^c ) + Ch ^t + Ch ^h - a combination of spotting of typical and leached chernozems with chernozems typical and meadow-chernozem soils.

V.V. Dokuchaev considered two groups of regularities that determine the change of soils in space: zonal and topographic, while the first in the initial stages of the development of soil science and soil geography received much more attention. Nevertheless, N. M. Sibirtsev , highlighting the “types of arable land”, considered it possible to even “variegated arable land” ( “chernozem with speckled salt marshes” , “podzolic loam with silts” , etc.) as one type (and singled out about 20 of these types), if this variegation is “of the same type, closes in the same pattern” , indicating that it is necessary to calculate the proportion of different soils in this type. He introduced the concept of "combination of soils" , the main factor in the formation of which he considered the relief.

G.N. Vysotsky in the 1910s revealed genetic relationships between soils occupying different positions in the relief. These ideas were developed by S. S. Neustruev , who divided the complexes in 1915 into those caused by the microrelief and mesorelief and, considering them not as a special case, but as a general rule, even suggested replacing the concept of “zonal soils” with “zonal complexes” , and later J. Milny in the 1930s, who formulated the concept of catena. Also, it was Neustruev who developed the first ideas about the evolution of the SPP associated with the evolution of the relief.

The concept of SPP was finally formulated after accumulation of sufficient factual material and the penetration of a systematic approach into soil geography in the 1960s and early 1970s , the main role in this was played by V. M. Fridland , who published in 1972 the classic monograph “Soil Structure” .

• Fridland V.M. Soil cover structure. M.: Thought, 1972.
• Agroecological assessment of lands, design of adaptive-landscape systems of agriculture and agricultural technologies. Edited by academician of the Russian Academy of Agricultural Sciences V.I. Kiryushin, academician of the Russian Academy of Agricultural Sciences A.L. Ivanov. Methodical guide.-M.: Federal State Institution "Rosinformagroteh", 2005.-784с. ISBN 5-7367-0525-7