Define soil profile: Over time, the localized physical, chemical and biological processes in the regolith (the layer of unconsolidated solid material above the bedrock) lead to the development of observable layers in the soil, called horizons. Read on to learn more about soil profile with diagram.
Each horizon differs in physical, chemical and biological characteristics. Together, the horizons in a particular location give each soil a distinctive soil profile (i.e. sequence of horizons from the surface down). It is evident when a vertical cut is made through the soil. Since the separations between each horizon are rarely distinct, these horizons described actually form a continuum in the soil profile.
Horizons of Soil
A typical soil profile usually has four horizons (Take a look at soil profile diagram). Each main horizon is denoted by a capital letter (0, A, B, C). Although there is some variation exists between different classification systems, the widely accepted horizon classification of the soil profile is given below. The following horizons are listed by their position from top to bottom within the soil profile.
4 Horizons Types
A typical soil profile which is made up of four major horizons one is the organic (0 horizon), and three are mineral horizons (A, B and C horizons). The 0 horizon lies at the soil surface; where organic matter accumulates. Types of soil profile are
O (O stands for organic matter), made up of large amounts of organic material in varying stages of decomposition (Figure 1: layers of soil diagram).
A (referred as topsoil), the topmost mineral horizons, rich in humus and dark in color. In older, well-developed soils, an E (being short for eluviated) horizon occur between the A and B horizons. It is used to label a horizon that has been significantly leached of its mineral and/or organic content, leaving a pale layer largely composed of silicates (zone of maximum leaching of minerals or eluviation) (Figure 1: layers of soil diagram).
B (referred as subsoil) little organic material and chemical composition are largely that of the underlying rock; also referred to as illuviated horizon or the zone of accumulation since minerals from above tend to concentrate here. The B horizon may be divided into B1, B2 and B3 types.
C (referred as parent rock), made up of weakly weathered parent material sit on unaltered bedrock (R) (Figure 1: layers of soil diagram).
Soil Profile Diagram
Figure 1: Layers of soil diagram
The soil profile and the relative thickness of the horizons are generally characteristic for different climate, the type of vegetative cover and different topographical situations. For example, in grassland soil humification is rapid, but mineralization is slow. In forest soil litter and root decay slowly. Hence humus layer is narrow, but mineralization is rapid so B horizon is broad.
Soil Erosion & Steps
Soil erosion is a process of detachment of soil particles, their transportation from one place to another and deposition elsewhere through water, wind, gravity, snow and other forces. Soil erosion involves three steps: 1. Detachment of soil particles from the main soil body. 2. Their transportation and 3. Their deposition at another places.
The major factors which cause soil erosion are rainfall, vegetation destruction, freezing and thawing, water flow and wind velocity. Numerous factors affect soil erosion depending upon the local conditions with regard to physical, chemical and biological nature of the soil. The major factors affecting the soil erosion are climate, topography, physical, chemical and biological characteristics of the soil, vegetation cover and land use.
FAQs on Soil Profile with Diagram
A soil profile is a vertical section of soil, like the one in the picture above. It lets you look at how the soil is put together. A soil profile is divided into layers called horizons.
The colour and texture of the soil provide a quick and easy way to distinguish between the different layers of a soil profile. Soil makes up the uppermost part of the Earth’s crust. Various organic minerals and granules of rock make up this crucial layer. Vegetation is able to flourish thanks to these layers of the Earth’s crust.
Soil theory had its origins in the work of a German scientist, Justus von Liebig (1803-1873), and in observations of marine terraces. The late 19th-century geological understanding of soils was presented in a monograph (1891) by geologist Nathaniel Shaler (1841-1906).
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