Podzolic Soil

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Podzolic Soil Definition

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What is podzolic soil meaning? Podzolic soil, podzolic also termed as podzol, or called the lessivé soil, is a soil that is usually formed in a broadleaf forest and is mostly characterized by the average leaching, which is also highly susceptible to compaction. 

The eluvium horizon is usually 4 cm to 8 cm thick and is low in iron and aluminium oxides and the humus. It is generally formed under moist, cool and acidic conditions, and only where the parent material, like the granite or the sandstone, is present and is rich in quartz. It is usually found under a huge layer of organic material during the process of decomposition, which has a thickness of 5 cm to 10 cm. Sometimes, the middle region often has a thin horizon of 0.5 cm to 1 cm. When the soil horizon gets bleached it goes over into another red or red-brown horizon which is also known as the so-called Podzolic B. The colour is normally strongest in the upper region, and the changes occur at a depth of 50 cm to 100 cm and it progresses to the part where the soil that is mainly unaffected by any of the processes, which is the part of the parent material. The solid profiles are named by the letters A which is the topsoil, E which is the eluviated soil, B which is the subsoil and C which is the parent material. The red yellow podzolic soil is a poor soil with many limitations, including low soil pH, low clay content, low aggregate stability, low nutrient content, and susceptibility to compaction. Organic matter is the only indicator of fertility in these soils.

In some of the Podzols, the E horizon is absent which can be because of being masked by the biological activity or is obliterated by the disturbance. The podzols that have very little or almost no E horizon development are often classified as the brown podzolic soils which are also called Umbrisols and Umbrepts.

Podzolization Process

The process of podzolization is a complex soil formation process due to which the organic matters are dissolved and ions of iron and aluminium are released through the weathering of various minerals from the organo-mineral complexes and are moved from the upper parts of the soil profile it goes and deposits in the deeper regions of the soil. Via this process, the eluvial horizon of the podzol becomes bleached and it turns into an ash-grey colour. The complexes move along with the percolating water and move further down to the illuviated horizons which are usually brown or are coloured red or black when they accumulate and are made up of cemented sesquidoxes and/or organic compounds. Thus, podzolization is typically a soil formation process in the podzols. 

The above-mentioned process of formation of podzol soil known as podzolization can be simplified into two main steps:

  • The mobilization and  the translocation of the organic matter, iron and aluminium from the surface horizon, and

  • The immobilization and the stabilization of the organic matter, the iron and aluminium into the subsoil.

Finally, podzolization also promotes the relocation of some of the nutrients such as copper, iron, manganese, molybdenum and phosphorus bringing them closer to the plant roots.

FAQ (Frequently Asked Questions)

1. What are the Podzol Soil Characteristics?

Ans: The podzolic soils are mostly infertile because of low nutrient content and aluminium toxicity. They are also physically limiting soils for any productive use. They are extremely acidic and have a very low pH. They have high carbon to nitrogen ratios and apart from lacking in many plant nutrients, they contain in some amounts the upper mineral zones.

2. What is Podzol Made of?

Ans: The podzol is formed under the forested landscapes. It is formed on a coarse parent material which is usually high in quartz. They contain a characteristic subsurface layer which is known as the spodic horizon and is made up of the accumulated humus and the metal oxides which are usually of iron and magnesium.

3. Are Podzol Soils Fertile?

Ans: No, Podzol soils are not fertile. They are infertile as they mostly lack the plant nutrients and minerals which are necessary for the growth of vegetation. Along with this, they have high aluminium toxicity. They also have very low base content and they are highly acidic causing them to have high pH.