Among the soils of the Kola region the most widespread are podzols, formed on sandy moraine rocks. They are met in the territories of coniferous forests, in the area of birch woodlands of the forest-tundra and tundra. Ferriferous and humus illuvial have a difference from other soils in its profile. It has a peculiar shift of the deep horizons.
You can find the difference between the color of its upper and lower horizons and the composition of the individual layers, when you are digging the soil to a one meter depth with a vertical slope. The uppermost horizon is fire-fang plant remains densely penetrated by roots. It is the organogenic horizon, denoted by the index A0. Here you can annually observe the processing of falling-away plant organs - leaves, needles, branches - with the involvement of soil organisms. The decomposition of plant fragments goes in two directions. The first is the absolute organic mineralization to the end product (water and carbon dioxide). The second is the humification - the specific humus elements formation, called humus and fulvic acids, constituting the basis of soil humus. Humus elements are met in the soil and similar materials, such as peat, silt and others. They are peculiar for the soil structure and they are natural high-polymer organic elements of the acidic medium. In the forests soils fulvic acids are formed in a greater extent. They are not similar to other organic matters. They are able to decompose many soil-forming minerals, constituting the basis of the rock.
Formed in organogenic horizon A0 fulvic acids, under the influence of subsoil flow and precipitation filterable through the soil precipitation, they penetrate into the mineral horizons of the soil or soil-forming rock. Gradual decomposition of minerals occur in the process of the interaction between this element and acidic solutions of fulvic acids. Soluble substances, released in this process (mainly oxides of ferric and aluminium), move deeper into the profile, while the upper part contain the silicon compound - quartz. Thus, the podzolic horizon A2, located directly under the A0 horizon, is forming.
The soil has peculiar properties to be washed out with water and filter precipitation in the form of meltwater and rain. Water, passing forest litter, comes upon the upper horizon, containing humus acids. They dissolve in water and then the water reaches the mineral soil layer. It leads to the interaction of humus acids with minerals, making up the soil-forming rock. The consequence of this interaction is the process of decomposition of minerals and advancement of chemical elements, being part of the composition of the soluble minerals, in the depth of the soil profile. In the end of these processes the normal effect is the formation of intense destruction horizon of minerals. This horizon is located right under the «forest litter» and it is called podzol. Its name it received because of the similar color with ash.
As far as podzolic horizon A2 consists mainly of quartz and other light minerals, its color is whitish, sometimes grey from the presence of organic matter (humus) therein. In addition, it is loose, powdery.
Some chemical elements such as sodium, magnesium, calcium leache out the soil with water and some parts of aluminum and ferric accumulate in the bottom of podzolic layer. Thus horizon leaching (illuvial) is formed. It is also called illuvial-ferric podzol.
Under podzolic it lies the illuvial horizon «B». There accumulate such leaching out podzolic horizon substances, as the hydroxides of aluminum and ferric in combination with humus elements - fulvic acids. Substance precipitation is carried out by varying the reaction, getting weak-acid in this environment and characterized by settling out these oxides. Presence in the horizon of a significant amount of ferric oxides gives it an ocher color from fulvous to brown. The color becomes dark brown, often nearly black, when there is a high content of humus. If the podzolic horizon usually has a small thickness (power), illuvial horizon is stretched and it can be subdivided into two subhorizons B1 and B2. The action of soil-forming factors weakens with depth and the soil becomes a normal moraine rock of gray colour with a greenish tint, that typical for the soils of this type of Murmansk region. In these soils normally contains large amounts of boulders and stones of different sizes.
This general scheme is rather applicable for the forming process of the most spread local soils on sandy and moraine rocks. But it does not mean that podzolic soils are the same. Theyare differ depending on relief and conditions of the ecological environment of the area.
Horizon’s power, their color and structure depend largely on the conditions of soil formation. In the tops of the flat hills, in pine crowberry or lichen forests you can commonly found low-powered podzols. As far as the amount of vegetable abscission in such forests is small, the organic horizon is also small - only 1-2 cm, that’s why there forms relatively little humus substances. Podzolic horizon is also low-powered, it is low in humus, its color is almost white. Illuvial horizon is also low-powered and it has bright ocher color. In general, the soil is characterized by shorter profile due to that these soils are called dwarf podzols.
In more humid places (in the lower parts of the slopes, in cranberry or blackberry pine forests) scientists observe much more abscission, the increase of organogenic and podzolic horizon’s power. Podzolic horizon’s coloring becomes dark (grey, dark grey) from the presence of humus in it; illuvial - dark fulvous or brown. In much more humid places (under the billberry or blueberry fir-groves) plant productivity and the abscission amount increases even more. Moreover, the decomposition of plant remains on the soil surface is slowed down in conditions of excess moisture. As a result, the condition and color of the horizons in these soils change more: organogenic horizon is converted into peat, its power reaches 10 centimeters or more; the color of podzolic horizon becomes darker; for the illuvial it is often dark brown, sometimes almost black.
Podzolic sandy soils are widespread in all areas of the Kola Peninsula and its natural zones. In tundra these soils occupy the tops and sloping hills. From the described above forest podzols they differ in low-powered podzolic horizon, usually dark-colored even in those soils, that are located in dry places. Often podzolic horizon in tundra soils is so thin that it is not always visible on the wall of the soil profile cut.
Except podzolic soils in tundra zone you can meet protomorphic soils, that can be regarded as the soils of primary soil formation. They are spread in the rocks (Barents sea coast) and represented as peaty cushions with a thin layer of sand (fine-grained soil) lying under it. Such soils are also formed in the rocks of the major mountain systems of the Khibiny, Monche-tundra and other places of high-altitude - tundra zone.
In addition to sandy podzolic soils on the territory of Murmansk region you can meet the soils formed in loamy and clayey soil forming rocks. Their profile significantly differs from the described above. Under the plant there is alayer of so-called gley horizon of bluish-gray color, sometimes with fulvous or reddish spots. The formation of this horizon is connected with the excess moisture, caused by weak filtering of loamy soils. When it is observed the lack of oxygen ferric compounds of which always are in a great amount, convert to the sour form (bivalent ferric salts), that endow it with a bluish coloration of the soil.
Podzolic sandy soils are widely used in agriculture. About the half of the arable area lands is located on these soils. Their land invasion is rather difficult: it is necessary to remove trees, remove large and small stones (boulders), that met in a great amount; after surface removal plow. Thus there is a mixing of the A2 and B horizons of natural soil and there creates loose arable layer (horizon A).
Natural soil have little nutrients, they contain very little humus (humus) and they are characterized by high acidity. In the process of their amelioration and growing there plants you need to enter it organic (manure, compost) and mineral (nitrogen, phosphorus and potassium) fertilizers and lime for reducing acidity. The arable layer of dark grey color is formed by the soil processing with plough or disc harrow and entering organic fertilizers. The deeper the arable layer, the darker its color, the more cultivated the soil, therefore, the more successful it is for growing crops.
Fertilizing should be moderate, because their abundance is expressed by the possible solution of surface and groundwater with hazardous substances. Moreover, the abundance of mineral fertilizers can lead to the accumulation of hazardous substances (such as nitrate) in agricultural products.
Sandy podzolic soils do not require the drainage, the main difficulty of land invasion is the gathering of stones and boulders. In some areas there are sandy soils, devoid of boulders. They are quite easy for mastering. But such soils have little humus. It is necessary to introduce a lot of organic matter (peat, manure) for their improving.
Peaty-podzolic soils are transitional between podzol and peat soils. They are characterized by more moisture and more powerful organogenic horizon that lies even more powerful podzolic horizon of dirty grey colour. Deeper it is observed the illuvial horizon of dark brown (almost black) color and greater density. These soils are fertile and productive, but they require drainage.