Soil Forming Processes

 The formation of soil is a complex process along with a lot of factors and processing ways. In takes a long period of time to develop even an inch of soil.

In this article, the basic processes of soil formation is discussed briefly.

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Pedogenesis is originated from the Greek term pedo/pedon meaning soil/earth and genesis meaning origin. So, Pedogenesis means ‘the origin of soil’. It is also termed as soil genesis.

Pedogenesis is the process of soil formation that is regulated by the effects of environment,  place  and history. In this process, parent material of soil is converted into soil in few steps.


Parent material in converted into regolith. This step is accomplished by weathering.

Regolith: The layer of unconsolidated solid material covering the parent material (bed-rock).

Weathering: The physical disintegration and ddecomposition of rocks and minerals under natural condition.


In this step, the regolith is converted into soil. It is associated with the action of Soil Forming Factors.


It is the removal and translocation of certain constituent’s viz. Clay, Fe2O3, Al2O3, SiO2, humus, CaCO3, other salts etc. by the percolating water from the upper to lower layers.


Illuviation is the process of deposition of soil materials (removed by eluviation) in the lower layers.


It is the process of precipitation and accumulation of calcium carbonate (CaCO3) at the base of B- horizon.


It is the reverse of calcification that is the process of removal of CaCO3 or calcium ions from the soil by leaching.


It is a collection of processes that includes eluviation of base cations, weathering transformation of Fe and Al compounds, mobilization of Fe and Al from surface horizons, and transport of these compounds to the B horizon as Fe and Al complexes.


It is the process that removes silica, instead of sesquioxides from the upper layers and thereby leaving sesquioxides to concentrate in the solum.


Melanization is the development of dark, humus-rich coatings on ped faces and mineral grains, rendering the horizon a dark brown or black.


The term glei is of Russian origin means blue, grey or green clay. It causes the development of a glei/gley horizon in the lower part of the soil profile above the parent material due to poor drainage
condition (lack of oxygen).


It is the process of transformation of raw organic matter into humus. It is extremely a complex process involving various organisms.


This process denotes the conversion of inorganic matter into organic matter.


It is the process of transformation of organic matter into inorganic matter.


It is the process of accumulation of salts, such as sulphates and chlorides of calcium, magnesium, sodium and potassium, in soils in the form of a salty (salic) horizon.


It is the removal of excess soluble salts by leaching from horizons or soil.


1. Feature image: https://forum.byjus.com/the-soil-which-is-formed-due-to-weathering-of-lava-rock-is-called.

2. Wikipedia

3. Class lecture of Bayazid Khan, Department of Soil, Water & Environment, University of Dhaka

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About Tarek Siddiki Taki

Currently studying at Department of Botany, University of Dhaka. E-mail: tareksiddikitaki@gmail.com Minimum monthly resolution- publish (1), revise (2), share (2)

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