Podzolic soil is formed under the influence of the podzolic process. Its maximum effect is manifested in the coniferous forest.
It is here that all the conditions necessary for its passage are present: the water regime of the flushing type, the reaction is stable acid, aggressive organic acids.
Forest litter is mainly represented by fiber, tannins and lignin, its reaction is acidic, but it contains insufficient nitrogen and calcium. Mushrooms decompose it mainly, and this contributes to the formation of aggressive fulvic acids. In addition, the upper layers of the soil are subject to vigorous leaching of readily soluble compounds and deep destruction of soil minerals. During these processes, the products of destruction dissolve, and together with acids and water fall below.
As a result, a podzolic or eluvial horizon is separated, in which there are few nutrients for plants, one-and-a-half oxides of aluminum and iron, silt particles, but a lot of crystalline quartz (SiO2) and amorphous silicic acid (SiO2 • 2), to which this horizon owes its light gray color, reminiscent of the color of ash.
Some of the substances that have been washed out of the podzolic horizon and forest litter are fixed below the eluvial layer and form a leaching horizon - the illuvial layer. It contains many colloidal and clay particles, iron and aluminum oxides, phosphorus compounds and some part of humus. The color of this horizon is often reddish brown.
A certain amount of substances that have been washed from the upper layers reaches the groundwater and is lost by the soil profile. So, the essence of the podzolic process is manifested in the destruction of minerals in the upper part of the soil under the influence of an acid reaction and the subsequent redistribution of the products of their destruction throughout the profile. It is also believed that this process can occur in combination with lessage (removal of clay particles from the upper soil layers without destroying their structure).
Podzolic soils have the following profile structure: A O + A 2 + B + C.
And O is a forest litter with a thickness of 3-5 centimeters, which consists of undecomposed and semi-decomposed remains of moss, lichens, needles, pieces of bark and the like.
And 2 is an eluvial, or podzolic layer, whitish or whitish-gray, having an unstable layered-tiled structure or completely structureless, not more than a quarter meter thick.
B is an illuvial red-brown or brown layer, dense, having a prismatic or blocky structure, up to a meter thick, it can be divided into subhorizons - B 1, B 2, and so on.
C is the parent rock, most often represented by clay or carbonate-free loam. At the border of the forest litter and the podzolic horizon, a layer A 0 A 1, 2 to 3 centimeters thick , can be distinguished, consisting of a well-decomposed lower part of the litter or the upper mineral layer of the A 1 A 2 profile, colored with humus substances.
Podzolic soil in its properties is unfavorable for growing cultivated plants on it. The humus horizon in it is practically absent, the reaction is highly acidic (pH = 4.0-4.5), its absorption capacity is from 3 to 15 mg • equiv / 100 grams of soil, which is quite small. In addition, podzolic soils are poorly saturated with bases - from 30 to 40%.
Nutrients such as phosphorus, potassium, nitrogen and others are also few. Podzolic soils are structureless, swim after rain, form a fairly dense crust after drying. All this negatively affects the plants.
In order to cultivate such lands, it is necessary to lime them, to introduce higher standards of both organic and mineral fertilizers. Plowing podzolic soils is necessary to a depth of 24 centimeters and to ensure their processing in accordance with all the rules.