Soil formation is a two-step process:
The transition from regolith to true soil occurs through the collaborative influence of soil-forming factors and processes.
Dokuchaiev (1889) established that the soils develop as a result of the action of soil forming factors
S = f (P, Cl, O)
Further, Jenny (1941) formulated the following equation
S = f (Cl, O, R, P, T, …)
Where,
Cl – environmental climate
O – Organisms and vegetation (biosphere)
R – Relief or topography
P – Parent material
T - Time
… - additional unspecified factors
The five soil forming factors, acting simultaneously at any point on the surface of the earth, to produce soil.
The passive soil-forming factors are the elements that serve as the origin of the soil-forming material and the conditions that influence it. They establish a foundation upon which the active soil-forming factors operate to facilitate the formation of soil.
It is that mass (consolidated material) from which the soil has formed.
Colluvium: This refers to materials that are poorly sorted and found near the base of steep slopes. They are transported due to the force of gravity.
Alluvium: Alluvium consists of materials that are transported and deposited by water. These materials are typically located along major river courses and at the lower portions of mountain slopes. They can also be found along small streams that flow out of drainage basins.
Lacustrine: Lacustrine materials are composed of substances that have settled out of the calm waters of lakes.
Moraine: Moraine is made up of a variety of materials that have been collected, mixed, broken down, transported, and deposited as a result of glacial ice or the water produced primarily from the melting of glaciers.
Loess or Aeolian: These materials are transported by the wind. When the texture is silty, it is referred to as loess, and when it is sandy, it is categorized as aeolian.
Eolian: Soils that develop on such transported parent materials are named after the parent material itself, such as alluvial soils from alluvium and colluvial soils from colluvium. However, in the initial stages, soil properties are primarily determined by the type of parent material.
As soil development progresses and leaching becomes more pronounced, the impact of the parent material on soil characteristics gradually wanes. In some soils, the parent material's composition can temporarily overshadow the influences of climate and vegetation. However, these soils are transient and only persist until chemical decomposition becomes active under the influence of climate and vegetation.
Formation of a standard soil profile is influenced by climate and vegetation.
The type of parent material significantly impacts profile development and leads to the creation of distinct soil types, particularly in the early stages of soil formation.
1. What are passive soil-forming factors? |
2. How does climate influence soil formation? |
3. What is the significance of parent material in soil formation? |
4. How does topography affect soil formation? |
5. Why is time considered a passive soil-forming factor? |
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