Search results
Jul 29, 2015 · Soil water is the amount of water present in the vadose zone, or the zone of unsaturated flow, of the soil profile. The term groundwater refers to the area of saturated flow in the soil. Water enters the soil profile through the process of infiltration, and then moves through the soil profile via percolation.
- PDF
The Soil Profile The vertical section of soil that shows the...
- PDF
- 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.
Are you a student? Get Britannica Premium for only 24.95 - a 67% discount!
Learn More
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
Soil is the most important raw material for agriculture. Agriculture provides food, clothing and shelter to all entities either directly or indirectly. Hence, soil is an inseparable part of our living. What is Soil Profile? The soil profile is a vertical section of the soil that depicts all of its horizons.
- 6 min
Jan 27, 2020 · CLIMATE- The climate is a very important factor in soil formation. It determines many things like, how much water will drain through different layers of the soil profile. Water is needed to convert the minerals into clay and pass on that clay to the lower layers.
Aug 3, 2024 · The ultimate size of the soil particle, called soil texture, has an important influence on soil permeability, water intake, and water storage capacity. Based on texture, soils are identified as sandy (2–0.05 mm average particle diameter), silty (0.05–0.002 mm), clayey (less than 0.002 mm), and loamy (mixture of sand, clay, and silt).
Jan 1, 2024 · Eluviation, illuviation, and humification are the three fundamental soil-forming processes that influence the formation of soil horizons and soil profile development. Eluviation is the process by which minerals and organic matter are removed from the upper soil horizons through the action of water, while illuviation is the process by which these materials are transported and deposited in lower ...
People also ask
Why is soil profile important?
What is soil profile?
Why is soil important?
How does water enter the soil profile?
How does soil drainage affect soil development?
How do micropores affect a soil profile?
Aug 4, 2021 · Soil life also plays an important role in soil formation, a process that takes centuries to thousands of years and a succession of different interlinked plants and soil biota. Insight in the interlinkages is of importance to understand the impact of human modification of habitats on soil diversity and functioning and to devise strategies to counteract soil loss and promote soil and habitat ...
