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Clay is a type of fine-grained natural soil material containing clay minerals [1] (hydrous aluminium phyllosilicates, e.g. kaolinite, Al 2 Si 2 O 5 4). Most pure clay minerals are white or light-coloured, but natural clays show a variety of colours from impurities, such as a reddish or brownish colour from small amounts of iron oxide .
Plants with shallow roots, might not withstand the soil contraction forces due to the shrinkage of clay in the dry season. The low water infiltration rate and hydraulic conductivity may lead to a perched water table form on top of the claypan layer. Water in the perched water table evaporates instead of uptake by plants, especially in the dry ...
Soil texture is determined by the relative proportion of the three kinds of soil mineral particles, called soil separates: sand, silt, and clay. At the next larger scale, soil structures called peds or more commonly soil aggregates are created from the soil separates when iron oxides, carbonates, clay, silica and humus, coat particles and cause ...
A so-called "cathedral" mound produced by a termite colony. Structures built by non-human animals, often called animal architecture, [1] are common in many species. Examples of animal structures include termite mounds, ant hills, wasp and beehives, burrow complexes, beaver dams, elaborate nests of birds, and webs of spiders.
Galen, the Greek philosopher and physician, was the first to record the use of clay by sick or injured animals in the second century AD. This type of geophagia has been documented in "many species of mammals, birds, reptiles, butterflies and isopods, especially among herbivores". [8]
In soils, clay is a soil textural class and is defined in a physical sense as any mineral particle less than 2 μm (8 × 10 −5 in) in effective diameter. Many soil minerals, such as gypsum , carbonates, or quartz, are small enough to be classified as clay based on their physical size, but chemically they do not afford the same utility as do ...
Expansive clay, also called expansive soil, is a clay soil prone to large volume changes (swelling and shrinking) directly related to changes in water content. [1] Soils with a high content of expansive minerals can form deep cracks in drier seasons or years; such soils are called vertisols .
They sequester nitrogen and other nutrients that might otherwise enter groundwater, and they fix nitrogen from the atmosphere, making it available to plants. Many organisms enhance soil aggregation and porosity, thus increasing infiltration and reducing surface runoff. Soil organisms prey on crop pests and are food for above-ground animals.