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Biotic and abiotic components
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- Soil is composed of various factors like air, water, minerals, and different living and non-living organic compounds. The entire composition of soil can be classified as biotic and abiotic components; the abiotic component includes the non-living things of soil while the biotic component includes the living organisms.
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Oct 31, 2024 · Soil is a complex natural resource that plays a vital role in supporting life on Earth. It acts as a medium for plant growth, a habitat for various organisms, and a crucial component of the Earth's ecosystem. Understanding soil composition and types is essential for sustainable agriculture, land management, and environmental conservation. This article delves deeper into the components of soil ...
- Overview
- Soil horizons
- Pedons and polypedons
Soil is the biologically active and porous medium that has developed in the uppermost layer of Earth’s crust. It serves as the reservoir of water and nutrients and a medium for the filtration and breakdown of injurious wastes. It also helps in the cycling of carbon and other elements through the global ecosystem.
What are the grain sizes in soil?
The grain size of soil particles are categorized into three groups: clay, silt, and sand. Clay measures less than 0.002 mm (0.0008 inch) in diameter, silt is between 0.002 mm (0.0008 inch) and 0.05 mm (0.002 inch), and sand is between 0.05 mm (0.002 inch) and 2 mm (0.08 inch).
What are the five factors of soil formation?
The evolution of soils and their properties is called soil formation, and according to pedologists, five fundamental soil formation processes influence soil properties. These five “state factors” are parent material, topography, climate, organisms, and time.
What are the layers of soil?
Soils differ widely in their properties because of geologic and climatic variation over distance and time. Even a simple property, such as the soil thickness, can range from a few centimetres to many metres, depending on the intensity and duration of weathering, episodes of soil deposition and erosion, and the patterns of landscape evolution. Nevertheless, in spite of this variability, soils have a unique structural characteristic that distinguishes them from mere earth materials and serves as a basis for their classification: a vertical sequence of layers produced by the combined actions of percolating waters and living organisms.
These layers are called horizons, and the full vertical sequence of horizons constitutes the soil profile (see the figure). Soil horizons are defined by features that reflect soil-forming processes. For instance, the uppermost soil layer (not including surface litter) is termed the A horizon. This is a weathered layer that contains an accumulation of humus (decomposed, dark-coloured, carbon-rich matter) and microbial biomass that is mixed with small-grained minerals to form aggregate structures.
Below A lies the B horizon. In mature soils this layer is characterized by an accumulation of clay (small particles less than 0.002 mm [0.00008 inch] in diameter) that has either been deposited out of percolating waters or precipitated by chemical processes involving dissolved products of weathering. Clay endows B horizons with an array of diverse structural features (blocks, columns, and prisms) formed from small clay particles that can be linked together in various configurations as the horizon evolves.
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Below the A and B horizons is the C horizon, a zone of little or no humus accumulation or soil structure development. The C horizon often is composed of unconsolidated parent material from which the A and B horizons have formed. It lacks the characteristic features of the A and B horizons and may be either relatively unweathered or deeply weathered. At some depth below the A, B, and C horizons lies consolidated rock, which makes up the R horizon.
Soils are natural elements of weathered landscapes whose properties may vary spatially. For scientific study, however, it is useful to think of soils as unions of modules known as pedons. A pedon is the smallest element of landscape that can be called soil. Its depth limit is the somewhat arbitrary boundary between soil and “not soil” (e.g., bedrock). Its lateral dimensions must be large enough to permit a study of any horizons present—in general, an area from 1 to 10 square metres (10 to 100 square feet), taking into account that a horizon may be variable in thickness or even discontinuous. Wherever horizons are cyclic and recur at intervals of 2 to 7 metres (7 to 23 feet), the pedon includes one-half the cycle. Thus, each pedon includes the range of horizon variability that occurs within small areas. Wherever the cycle is less than 2 metres, or wherever all horizons are continuous and of uniform thickness, the pedon has an area of 1 square metre.
Soils are encountered on the landscape as groups of similar pedons, called polypedons, that contain sufficient area to qualify as a taxonomic unit. Polypedons are bounded from below by “not soil” and laterally by pedons of dissimilar characteristics.
- Garrison Sposito
Mar 25, 2022 · Soil, in general, is classified into four different types depending on its composition and the size of particles. The four types of soil are: A. Sandy Soil. Sandy soil is a type of soil that contains a higher proportion of sand and less clay. Sandy soil is light, dry, and warm that tends to be more acidic than other types of soil.
Oct 19, 2023 · These soil components fall into two categories. In the first category are biotic factors—all the living and once-living things in soil, such as plants and insects. The second category consists of abiotic factors, which include all nonliving things—for example, minerals, water, and air.
In this article, we’ll discuss soil composition, formation of soil, and different types of soil, such as sandy, clay, silt, peat, chalk, and loamy soil. The layer of earth that is composed of soil and involved in the process of soil formation is called Pedosphere.
What are the soil types? To identify, understand, and manage soils, soil scientists have developed a soil classification or taxonomy system. Like the classification systems for plants and animals, the soil classification system contains several levels of detail, from the most general to the most specific.
May 16, 2019 · There are five basic components of soil that, when present in the proper amounts, are the backbone of all terrestrial plant ecosystems. Figure 1. Soil is composed of a matrix of minerals, organic matter, air, and water. Each component is important for supporting plant growth, microbial communities, and chemical decomposition. Image courtesy of FAO.
