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Soil plays a vital role in the Earth’s ecosystem and without soil, human life would be very difficult. Caption: A pine tree's root system with mycorrhizal threads (hyphae) that assist the tree to absorb additional nutrients. Credit: David Read. Soil provides plants a foothold for their roots and holds the necessary nutrients for plants to grow.
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Soil degradation, where soil loses the physical, chemical, or biological qualities that support life, is a natural process but it is being accelerated by human activity.
- Jon Heggie
- 2 min
Nov 11, 2024 · However, when soil becomes damaged or degraded, it can release CO2 or methane back into the atmosphere, thereby accelerating – rather than decelerating – the impact of climate change. As John Scott, Zurich’s Head of Sustainability Risk, says: “This is why the way in which we use land for agriculture is so important.
What damages soil structure? There are many reasons why a soil may become damaged. The use of heavy machinery is known to compact soil, which means that soil is less permeable to water, which increases the likelihood of soil erosion and flooding. High livestock densities can also compact the 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
Aug 15, 2017 · They now advocate for the promotion of sustainable soil practices. This will work towards securing a productive food system. It will improve all livelihoods. It will lead to a healthy environment. Soil is important. It's important to microorganisms. Plants rely on it. Animals need it. Humans won't survive without it. It's undeniable.
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Why is soil important?
What are soil functions?
Why is promoting good soil structure important?
What is soil health?
Why is soil health management important?
Why does soil matter?
Soil health is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. Healthy soil gives us clean air and water, bountiful crops and forests, productive grazing lands, diverse wildlife, and beautiful landscapes. Soil does all this by performing five essential functions:
