Gray forest soils are formed in the forest-steppe zone under the conditions of periodically-washing water regime under the canopy of broad-leaved ( oak mixed with linden , maple , ash ) mixed ( birch mixed with fir and pine or pine-birch mixed with larch ) or small-leaved birch ( aspen ) forests with diverse and abundant grasses. One centimeter of soil is formed in nature in 250-300 years, twenty centimeters in 5-6 thousand years.
Gray forest soils are widespread in the temperate zone of the Northern Hemisphere . Mother rocks are represented: in the European part of Russia - by loess , loess-like and cover loams , sometimes - moraine deposits; in Western and Eastern Siberia - mainly loesslike loams and clays . The relief is wavy, strongly and deeply dissected by water erosion in the European part; flat - in Western Siberia; gently slumpy, or tuberous micro- and mesorelief - in Eastern Siberia.
Content
Origin
The study of the origin of gray forest soils in Russia is associated with the names of V.V. Dokuchaev , S.I. Korzhinsky , V.I. Taliev , V.R. Williams , I.V. Tyurin and other scientists. V.V. Dokuchaev (1883) believed that gray forest soils formed as an independent zonal type under grassy broad-leaved forests ( oak forests ) of the forest-steppe zone . S. I Korzhinsky (1887) developed the hypothesis of the formation of gray forest soils as a result of degradation (deterioration of properties) of chernozems when exposed to forests.
In contrast to the hypothesis of S.I. Korzhinsky, V.I. Taliev and P.N. A close judgment on the formation of gray forest soils was expressed by V.R. Williams. Studies by I.V. Tyurin (1935) showed that gray forest soils in the eastern regions of the European territory of the zone were formed as a result of the evolution of soddy - gley soils when their water regime changed as a result of the development of drainage of the territory by a ravine - gully network and river valleys .
All theories considered reflect the possible paths of formation of gray forest soils under different physical and geographical conditions, which ensure the formation of a fairly well- humified profile with signs of podzolization. A modern understanding of the genesis of gray forest soils consists in the fact that this type of soil was formed under the predominant influence of the sod process in combination with the weak development of the podzolic process with the participation of lessage [1] .
Morphology
- A 0 - forest litter , thin (up to 3-5 cm).
- A 1 is a humus horizon of gray color, lumpy-fine-grained or lumpy-grainy-dusty structure , thin (15-30 cm), densely penetrated by plant roots forming in the upper part of the turf .
- A 1 A 2 - humus- eluvial horizon, light gray, lumpy or lumpy-tiled structure, with abundant whitish siliceous powder; in dark gray forest soils may be absent.
- BA 2 [2] - eluvial-illuvial horizon of grayish-brown or grayish-brown color, finely lumpy structure, the surface of the individual is covered with a layer of siliceous powder.
- B - illuvial horizon, brownish-brown in color, pronounced nutty or prismatic-nutty structure. The surface of the individual is covered with dark brown or dark brown glossy films of organic or organomineral composition. According to the severity of these characteristics can be divided into horizons B 1 and B 2 .
- BС (к) - transitional horizon from the illuvial to the mother breed. It is characterized by fewer illuvial films, a less distinct structure and lower density than horizon B. Often there are carbonate neoplasms in the form of pseudomycelia, cranes, white eyes and fuzzy spots.
- C to - mother breed .
Properties
| Physico-chemical properties of gray forest soils [3] | |||||||||
|---|---|---|---|---|---|---|---|---|---|
| Horizon (depth, cm) | Humus% | Mass loss during calcination,% | Exchange grounds | Hydrolytic acidity | Degree of saturation grounds,% | pH | |||
| Ca 2+ | Mg 2+ | Σ (Ca 2+ + Mg 2+ ) | |||||||
| mEq / 100 g soil | H 2 O | Kcl | |||||||
| Light gray forest highly podzolized on loesslike loam | |||||||||
| A 0 (0-3) | - | 69.67 | - | - | - | - | - | 6.3 | 5.9 |
| A 1 (3-9) | 4.45 | 7.14 | 11.1 | 3,1 | 14.2 | 5,4 | 72,4 | 6.8 | 5,6 |
| A 1 A 2 (9-17) | 1.79 | 3.06 | 6.4 | 3.2 | 9.6 | 3.9 | 70.9 | 6.9 | 5.5 |
| BA 2 (26–36) | 0.41 | 1.97 | 8.0 | 2.9 | 10.9 | 2,3 | 82.8 | 6.8 | 5.3 |
| B 1 (45–65) | 0.28 | 3.01 | 12.9 | 7.0 | 19.9 | 3.8 | 83.9 | 5.8 | 4,5 |
| B 2 (75–90) | 0.21 | 2.71 | 13.0 | 6.1 | 19.1 | 4.3 | 81.7 | 5.8 | 4.3 |
| B 3 (105-120) | - | 2,33 | 11,2 | 5,0 | 16,2 | 3.3 | 83.0 | 5.7 | 4.2 |
| BC to (130-145) | - | 9.11 | - | - | - | - | - | 7.6 | 6.6 |
| Dark gray slightly podzolized on loesslike loam | |||||||||
| A 0 (0-2) | - | 73.09 | - | - | - | - | - | 6.4 | 6.1 |
| A 1 (2-13) | 6.34 | 8.20 | 19,4 | 6.2 | 25.6 | 3.0 | 89.4 | 6.4 | 5.5 |
| A 1 A 2 (15-25) | 2,56 | 3.90 | 16,0 | 6.4 | 22.4 | 2,8 | 89.0 | 6.9 | 5.7 |
| B 1 (30–45) | 1,5 | 4.11 | 19.2 | 4.8 | 24.0 | 2,3 | 91.2 | 6.8 | 5.5 |
| B 2 (60–75) | 0.96 | 3.44 | 17.6 | 7.4 | 25.0 | 2,4 | 91.1 | 6.5 | 5.5 |
| B 3 (95-115) | 0.58 | 2.62 | 16,0 | 8.0 | 24.0 | 2.0 | 92.2 | 6.6 | 5.3 |
| BC to (135-145) | - | 5.39 | - | - | - | - | - | 8.1 | 7.3 |
Classification
According to the USSR Soil Classification of 1977 , the type of gray forest soil is subdivided into three subtypes:
- Light gray forest : the humus horizon is thin - 15-20 cm, light gray in color, as well as humus-eluvial, characterized by a slate or tile structure; the illuvial horizon is well defined, very dense, with a nutty structure. The humus content is from 1.5–3% to 5%; fulvic acids predominate in its composition, which determines the acid reaction of the soils of this subtype. In general, by morphological characteristics and properties, they are close to sod-podzolic soils .
- Forest gray : the sod process is more pronounced, and the podzolic one is weaker than in light gray. The humus horizon is gray in color, with a thickness of 25-30 cm, the humus content is from 3-4% to 6-8%, humic acids slightly dominate in its composition. The soil solution has an acidic reaction. The eluvial-illuvial horizon may not be expressed.
- Dark gray forest : among gray forest soils it is distinguished by the most intense sod process and the least podzolic (siliceous powder is not abundant, sometimes it may be absent at all). The thickness of the humus horizon is up to 40 cm, the humus content is from 3.5-4% to 8-9%, humic acids prevail over fulvic acids. The reaction of the medium is slightly acidic. The presence of calcium neoplasms at a depth of 120-150 cm is characteristic.
| Facial subtypes of gray forest soils | ||||
|---|---|---|---|---|
| Light gray forest warm freezing | Light gray forest moderately warm freezing | Light gray forest temperate freezing | Light gray forest moderately cold, long-term freezing | - |
| Light gray forest warm freezing mastered | Light gray forest moderately warm freezing mastered | Light gray forest temperate long-term freezing developed | Light gray forest moderately cold long freezing developed | - |
| Light gray forest warm freezing cultivated | Light gray forest moderately warm freezing cultivated | Light gray forest temperate long-term freezing cultivated | Light gray forest moderately cold long-term freezing cultivated | - |
| Gray forest warm freezing | Gray forest moderately warm freezing | Gray forest temperate freezing | Gray forest moderately cold, long-term freezing | Gray forest cold freezing |
| Gray forest warm freezing mastered | Gray forest moderately warm freezing mastered | Gray forest temperate long-term freezing developed | Gray forest moderately cold | Gray forest cold long freezing mastered |
| Dark gray forest warm freezing | Dark gray forest moderately warm freezing | Dark gray forest temperate freezing | Dark gray forest moderately cold, long-term freezing | Dark gray forest cold freezing for a long time |
The following are distinguished :
- Ordinary
- Residual Carbonate
- Contact meadow
- Variegated
- With a second humus horizon
Separation into types is carried out by:
- boiling depth
- high boiling (above 100 cm)
- deep boiling (deeper than 100 cm)
- humus horizon power (A 1 + A 1 A 2 )
- powerful (> 40 cm)
- medium-powerful (40–20 cm)
- low power (<20 cm)
Agricultural Use
Gray forest soils are actively used in agriculture for growing fodder , grain and fruit and vegetable crops. To increase fertility, systematic application of organic and mineral fertilizers , grass sowing, and a gradual deepening of the arable layer are used. Due to the poorly expressed ability of gray forest soils to accumulate nitrates [4] , nitrogen fertilizers are recommended to be applied in the early spring.
They are characterized by rather high fertility and, when used correctly, give good crop yields. Particular attention in the zone of gray forest soils should be paid to measures to combat water erosion, since it covered large areas of arable land. In some provinces, eroded to varying degrees, soils account for 70-80% of the arable land. As a result of insufficient application of organic fertilizers, the humus content in the arable layer of gray forest soils decreases. For optimal humus content, organic fertilizers must be applied. The average annual dose is 10 tons per 1 ha of arable land, which is achieved using manure, peat, various organic composts, green manure, straw and other organic materials. An important measure in the agricultural use of gray soils is liming. When liming, the excess acidity of gray forest soils is neutralized and the nutrient supply to the plant roots improves. Lime mobilizes soil phosphates, which leads to the entrainment of phosphorus available to plants; when lime is added, the mobility of molybdenum increases, microbiological activity increases, the level of development of oxidative processes increases, calcium humates are formed more, soil structure, quality of crop production improves. Most gray forest soils contain an insufficient amount of assimilable forms of nitrogen, phosphorus and potassium, therefore the use of mineral fertilizers is powerful factor in increasing crop yields.
Essential for increasing the fertility of gray forest soils is the regulation of their water regime [5] .
See also
- Chernozems
Notes
- ↑ Kovrigo, Kaurichev, Burlakova, 2000 .
- ↑ Usually this horizon is designated as A 2 B, but it is more correct to designate it as BA 2 , thereby indicating a slight manifestation of the eluvial process and the fundamental difference between this horizon and the horizon A 2 B of podzolic soils .
- ↑ Fundamentals of Soil Science, 2004 , p. 276.
- ↑ Fundamentals of Soil Science, 2004 , p. 278.
- ↑ Kovrigo, Kaurichev, Burlakova, 2000 , p. 273.
Literature
- Bobrovsky M.V. Forest soils of European Russia: biotic and anthropogenic factors of formation / Ed. Ed .: Doctor of Biological Sciences A. S. Komarov ; Reviewers: Doctor of Biological Sciences, prof. L.O. Karpachevsky , Doctor of Geological Sciences, prof. I.V. Ivanov ; Institute of Physico-Chemical and Biological Problems of Soil Science of the Russian Academy of Sciences . - M .: Partnership of scientific publications of KMK, 2010. - 360, [32] p. - 600 copies. - ISBN 978-5-87317-733-2 .
- Kovrigo V.P., Kaurichev I.S., Burlakova L.M. Soil Science with the Fundamentals of Geology . - M .: Kolos, 2000 .-- 416 p. - (Textbooks and study guides for students of higher educational institutions). - ISBN 5-10-003135-2 . (inaccessible link)
- Fundamentals of soil science and soil geography / Ed. S.P. Kulizhsky and A.N. Rudogo. - Tomsk: Publishing House of TSPU, 2004 .-- 384 p.
Links
- Gray forest soils - an article from the Great Soviet Encyclopedia .
- Gray forest soils (inaccessible link) (inaccessible link from 06/14/2016 [1146 days]) - Vocabulary for Natural Sciences