Product Code Database
Caliche () is a soil accumulation of soluble calcium carbonate at depth, where it precipitates and binds other materials—such as gravel, sand, clay, and silt. It occurs worldwide, in aridisol and mollisol soil orders—generally in arid or semiarid regions, including in central and western Australia, in the Kalahari Desert, in the High Plains of the western United States, in the Sonoran Desert, Chihuahuan Desert and Mojave Desert of North America, and in eastern Saudi Arabia at Al-Ahsa Oasis. Caliche is also known as calcrete or kankar (in India). It belongs to the . The term is borrowed from Spanish and is originally from the Latin word , meaning lime.
Caliche is generally light-colored but can range from white to light pink to reddish-brown, depending on the minerals present. Caliche is a mark of older landscapes. It generally occurs on or very near the surface. Where caliche layers originate at some depth from the soil surface, intact landscapes and buried landscapes are more likely than eroded surfaces to have caliche well below the soil surface. Layers vary from a few inches to feet thick, and multiple layers can exist in a single location. The caliche layer in a soil profile is sometimes called a K horizon. (2025). 9780199653065, Oxford University Press. ISBN 9780199653065
In northern Chile and Peru, caliche also refers to mineral deposits that include nitrate salts.Chong et al. 2007, p. 211.A Most Damnable Invention: Dynamite, Nitrates, and the Making of the Modern World, Stephen R. Bown, Macmillan, 2005, , p. 157. Caliche can also refer to various claylike deposits in Mexico and Colombia. In addition, it has been used to describe some forms of quartzite, bauxite, kaolinite, laterite, chalcedony, opal, and soda niter.
A similar material, composed of calcium sulfate rather than calcium carbonate, is called gypcrust.
However, caliche also forms in other ways. It can form when water rises through capillary action. In an arid region, rainwater sinks into the ground very quickly. Later, as the surface dries out, the water below the surface rises, carrying up dissolved minerals from lower layers. These precipitate as water evaporates and carbon dioxide is lost. This water movement forms a caliche that is close to the surface. Caliche can also form on outcrops of porous rocks or in rock fissures where water is trapped and evaporates. In general, caliche deposition is a slow process, requiring several thousand years.
The depth of the caliche layer is sensitive to mean annual rainfall. When rainfall is around per year, the caliche layer will be as shallow as . When rainfall is around per year, the caliche layer will be at a depth of around . The caliche layer disappears complete in temperate climates if annual rainfall exceeds .
The source of the calcium in caliche may be the underlying bedrock, but caliche can form even over bedrock that is not rich in calcium. This is attributed to calcium brought in as aeolian dust.
One of the world's largest deposits of calcrete is in the Makgadikgadi Pans in Botswana, where surface calcretes occur at the location of a now-desiccated prehistoric lake.C. Michael Hogan (2008) Makgadikgadi, The Megalithic Portal, ed. A. Burnham [1]
Highly indurated (hardened) caliche is known as calcrete, and it gives rise to characteristic landforms in arid environments. Calcrete is found throughout the geologic record, forming a record of past climate. Examples include Mississippian calcretes in South Wales and Pliocene to Pleistocene caprock of the Llano Estacado of Texas, US, and Mormon Mesa, Nevada, US.
Caliches can store significant amounts of carbon, making them of significance to the overall global carbon cycle.
In Jurassic geological settings, the caliche is often indicator of warm climate with well marked wet-dry seasonality that could indicate seasonal monsoons.
The Great House at Casa Grande Ruins National Monument, Arizona, US, was built with walls of caliche. Caliche was also used in mortars used in of the Mayan buildings in the Yucatán Peninsula in Mexico. A dormitory in Ingram, Texas, and a demonstration building in Carrizo Springs, Texas, for the United States Department of Energy were also built using caliche as part of studies by the Center for Maximum Potential Building Systems. (2025). 9781000366549 ISBN 9781000366549
In many areas, caliche is also used for road construction, either as a surfacing material, or more commonly, as base material. It is one of the most common road materials used in Southern Africa. Caliche is widely used as a base material when it is locally available and cheap. However, it does not hold up to moisture (rain), and is never used if a hard-rock base material, such as limestone, is available. (1982). 9780803107878, American Society for Testing & Materials. ISBN 9780803107878
The deposits contain an average of 7.5% sodium nitrate, as well as sodium sulfate (18.87%), sodium chloride (4.8%), and smaller amounts of potassium, calcium, magnesium, borate, iodine, and perchlorate. About two-thirds of the deposits are insoluble gangue minerals. The caliche beds are from 2 cm to several meters thick in alluvial deposits, where the soluble minerals form a cement in unconsolidated regolith. Nitrate-bearing caliche is also found impregnating bedrock to form bedrock deposits.
Caliche is the main iodine ore in Chile and the country is the world's prime producer of this element in addition to hosting over half of the worlds mineral reserve of iodine. USGS Iodine Production Statistics SQM is Chile's main iodine producer. Iodine at SQM is extracted from caliche ore but requires also sulphur, ammonium nitrate, sulfuric acid, kerosene, water, electricity and fossil fuel, mainly diesel.
Caliche and agriculture
Agriculture may not be compatible with caliche. First, an impermeable caliche layer prevents water from draining properly, which can keep roots from getting enough oxygen, and potentially cause salts to build up in the soil and turn it basic. Basic soil, along with calcium carbonate from the caliche, can prevent plants from getting enough nutrients, especially iron. An iron deficiency makes the youngest leaves turn yellow. Soil water content above the caliche bed during wet spells can make the condition worse. Second, the impermeable nature of caliche beds impairs plant roots, limiting access to nutrients, water, and sound anchorage. Third, caliche's hardness can also make digging for irrigation projects such as canals more difficult.
See also
Further reading
(2025). 9781862392199, Geological Society of London. ISBN 9781862392199
External links
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