Podzolic soils.

Podzolic soil is formed under the influence of the podzolic process. Its maximum impact is manifested in the coniferous forest.

It is here that all the conditions necessary for its passage are present: a water regime of the washing type, the reaction is a stable acidic, aggressive organic acids.

Forest litter is mainly fiber, tannins and lignin, its reaction is acidic, but nitrogen and calcium contain not enough. Its decomposition is mainly fungi, and this contributes to the formation of aggressive fulvic acids. In addition, the upper layers of the soil are subject to vigorous washing out of readily soluble compounds and the profound destruction of soil minerals. During these processes, the products of destruction dissolve, and together with acids and water fall lower.

As a result, a podzolic or eluvial horizon is separated out, in which there are few nutrients for plants, sesquioxides of aluminum and iron, silt particles, but a lot of crystalline quartz (SiO2) and amorphous silicic acid (SiO2 • H2O), which this horizon owes its light- Gray color, reminiscent of the color of ash.

Some of the substances that have been washed from the podzolic horizon and forest litter are fixed below the eluvial layer and form a washout horizon - an illuvial layer. It contains a lot of colloidal and clay particles, iron and aluminum oxides, phosphorus compounds and some 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 soil-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 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 levies (the removal of clay particles from the upper soil layers without destroying their structure).

Podzolic soils have the following structure of the profile: AO + A 2 + B + C.

A O is a forest litter 3 to 5 centimeters thick, which consists of undecomposed and half-decomposed remains of moss, lichens, needles, pieces of bark and the like.

A 2 is an eluvial or podzolic layer whitish or whitish-gray, having a weak lamellar-platy structure or even completely structureless, not more than a quarter of a meter in thickness.

B is an illuvial red-brown or brown layer, dense, having a prismatic or lumpy structure, up to a meter in thickness, it can be divided into subhorizons - B 1, B 2, and so on.

C is a parent rock, often represented by clay or non-calcareous loam. On the boundary of the forest litter and podzolic horizon, a layer A 0 A 1, 2-3 cm thick, consisting of a well decomposed lower part of the litter or a humus-colored upper mineral layer of the profile A 1 A 2 can be distinguished.

Podzolic soil is unfavorable in its properties for growing cultivated plants on it. The humus horizon is practically absent in it, the reaction is strongly acidic (pH = 4.0-4.5), its absorption capacity is from 3 to 15 mgEq / 100 grams of soil, which is quite small. In addition, podzolic soils are poorly saturated with bases - from 30 to 40%.

Nutrient elements, such as phosphorus, potassium, nitrogen and others are also small. Podzolic soils are structureless, they swim after the rain, they form a fairly dense crust after drying. All this has a negative effect on plants.

To conduct the cultivation of such lands, they must be limed, make higher rates of both organic and mineral fertilizers. It is necessary to plow podzolic soils up to a depth of 24 centimeters and ensure their processing according to all the rules.

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