In both the World Reference Base for Soil Resources (WRB) and the USDA soil taxonomy, a Vertisol (Vertosol[1] in the Australian Soil Classification) is a soil in which there is a high content of expansive clay minerals, many of them known as montmorillonite, that form deep cracks in drier seasons or years. In a phenomenon known as argillipedoturbation, alternate shrinking and swelling causes self-ploughing, where the soil material consistently mixes itself, causing some Vertisols to have an extremely deep A horizon and no B horizon. (A soil with no B horizon is called an A/C soil). This heaving of the underlying material to the surface often creates a microrelief known as gilgai.

Vertisols typically form from highly basic rocks, such as basalt, in climates that are seasonally humid or subject to erratic droughts and floods, or that impeded drainage. Depending on the parent material and the climate, they can range from grey or red to the more familiar deep black (known as "black earths" in Australia, "black gumbo" in East Texas, and "black cotton" soils in East Africa).

Vertisols are found between 50°N and 45°S of the equator. Major areas where Vertisols are dominant are eastern Australia (especially inland Queensland and New South Wales), the Deccan Plateau of India, and parts of southern Sudan, Ethiopia, Kenya, and Chad (the Gezira), and the lower Paraná River in South America. Other areas where Vertisols are dominant include southern Texas and adjacent Mexico, central India, northeast Nigeria, Thrace, New Caledonia and parts of eastern China.

The natural vegetation of Vertisols is grassland, savanna, or grassy woodland. The heavy texture and unstable behaviour of the soil makes it difficult for many tree species to grow, and forest is uncommon.

The shrinking and swelling of Vertisols can damage buildings and roads, leading to extensive subsidence. Vertisols are generally used for grazing of cattle or sheep. It is not unknown for livestock to be injured through falling into cracks in dry periods. Conversely, many wild and domestic ungulates do not like to move on this soil when inundated. However, the shrink-swell activity allows rapid recovery from compaction.

When irrigation is available, crops such as cotton, wheat, sorghum and rice can be grown. Vertisols are especially suitable for rice because they are almost impermeable when saturated. Rainfed farming is very difficult because Vertisols can be worked only under a very narrow range of moisture conditions: they are very hard when dry and very sticky when wet. However, in Australia, Vertisols are highly regarded, because they are among the few soils that are not acutely deficient in available phosphorus. Some, known as "crusty Vertisols", have a thin, hard crust when dry that can persist for two to three years before they have crumbled enough to permit seeding.

In the USA soil taxonomy, Vertisols are subdivided into:

  • Aquerts: Vertisols which are subdued aquic conditions for some time in most years and show redoximorphic features are grouped as Aquerts. Because of the high clay content, the permeability is slowed down and aquic conditions are likely to occur. In general, when precipitation exceeds evapotranspiration, ponding may occur. Under wet soil moisture conditions, iron and manganese are mobilized and reduced. The manganese may be partly responsible for the dark color of the soil profile.
  • Cryerts: They have a cryic soil temperature regime. Cryerts are most extensive in the grassland and forest-grassland transitions zones of the Canadian Prairies and at similar latitudes in Russia.
  • Xererts: They have a thermic, mesic, or frigid soil temperature regime. They show cracks that are open at least 60 consecutive days during the summer, but are closed at least 60 consecutive days during winter. Xererts are most extensive in the eastern Mediterranean and parts of California.
  • Torrerts: They have cracks that are closed for less than 60 consecutive days when the soil temperature at 50 cm is above 8 °C. These soils are not extensive in the U.S., and occur mostly in west Texas, New Mexico, Arizona, and South Dakota, but are the most extensive suborder of Vertisols in Australia.
  • Usterts: They have cracks that are open for at least 90 cumulative days per year. Globally, this suborder is the most extensive of the Vertisols order, encompassing the Vertisols of the tropics and monsoonal climates in Australia, India, and Africa. In the U.S. the Usterts are common in Texas, Montana, Hawaii, and California.
  • Uderts: They have cracks that are open less than 90 cumulative days per year and less than 60 consecutive days during the summer. In some areas, cracks open only in drought years. Uderts are of small extent globally, being most abundant in Uruguay and eastern Argentina, but also found in parts of Queensland and the "Black Belt" of Mississippi and Alabama.
a Vertisol profile
Used inWRB, USDA soil taxonomy
WRB codeVR
Key processclay pedoturbation
Climatetropical savanna, semi-arid, humid subtropical, Mediterranean



  • IUSS Working Group WRB: World Reference Base for Soil Resources 2014, Update 2015. World Soil Resources Reports 106, FAO, Rome 2015. ISBN 978-92-5-108369-7. (PDF 2,3 MB).
  • Soil Survey Staff: Keys to Soil Taxonomy. 12th edition. Natural Resources Conservation Service. U.S. Department of Agriculture. Washington D.C., USA, 2014.
  1. ^ "Australian Soil Classification - Vertosols". CSIRO. Retrieved 8 February 2016.

See also

Agriculture in Tanzania

Agriculture is the main part of Tanzania's economy. As of 2016, Tanzania had over 44 million hectares of arable land with only 33 percent of this amount in cultivation. Almost 70 percent of the poor population live in rural areas, and almost all of them are involved in the farming sector. Land is a vital asset in ensuring food security, and among the nine main food crops in Tanzania are maize, sorghum, millet, rice, wheat, beans, cassava, potatoes, and bananas. The agricultural industry makes a large contribution to the country's foreign exchange earnings, with more than US$1 billion in earnings from cash crop exports.The 7 main cash crops are as follows;



Cashew nuts



TobbaccoAt one point in its agricultural history, Tanzania was the largest producer of sisal in the world.The agriculture sector faces various challenges and had been the governments top priority to develop to reduce poverty and increase productivity. Farming efficiently has been a challenge for many farmers, and lack of finances and farming education has caused many to remain subsistence farmers. Farm sizes remain very small with an average plot size being around 2.5 ha.Challenges on the Agriculture Industry of Tanzania include lack of agricultural technology, droughts, floods, and agriculture temperature shocks. These pose severe challenges to the living standards of most of people involved in the Agriculture Industry in Tanzania and create huge increases in unemployment, hunger, malnutrition and starvation, and diseases rates.Large declines in commodity prices, decreased export revenues, increased trade and budget deficits all amount to hindering the growth of the country's gross domestic product (GDP). The Agriculture Industry in Tanzania represents 32.4 percent of GDP of Tanzania.


Argillipedoturbation, sometimes referred to as self-mulching, is a process of soil mixing caused by the shrinking and swelling of the smectite clays contained in the soil. It is an effect specific to soils of the vertisolic variety, and is triggered by the constant cycles of wetting and drying It is characterized by 1 centimetre (0.39 in) wide, 50 centimetres (20 in) deep vertical cracks in the solum that contain differing materials from the rest of the soil layer they are found in, as well as sloughed-in surface materials. In order for argillipedoturbation to occur, the soil must be at least 30% clay content. The expression of argillipedoturbation depends to a large degree on the exact clay content of the soil, as well as on what other minerals make up the soil composition.Argillipedoturbation can be strong enough that it can affect the soil horizons by combining the different horizons, making them difficult to distinguish. It can also result in a gently-rolling surface referred to as gilgai topography and in the dramatic soil inclusions known as slickensides. In addition, argillipedoturbation sometimes results in a chernozemic-like A-type horizon, or one resembling a gleysolic order soil. This process can also affect the distribution of rock fragments, by moving fragments at the surface to lower soil layers and vice versa.The effects of this process are useful in agriculture, as the organic surface materials fertilize the soil and cause them to become very productive when irrigated. However, they are very difficult to plow and manage due to the high, thoroughly mixed clay content.

Black Banks Creek

Black Banks Creek is a stream in the U.S. state of South Dakota.Black Banks Creek is lined with vertisol giving its banks a black tint.

Black soil

Black soil may refer to:

Chernozem, fertile black soils found in eastern Europe, Russia, India and the Canadian prairies

Muck (soil), a soil made up primarily of humus from drained swampland

Vertisol, dark cracking soils with a high clay content found between 50° N and 45° S of the equator

Terra preta, “black earth” or soil of the Amazon river basin

Canadian system of soil classification

The Canadian System of Soil Classification is more closely related to the American system than any other, but they differ in several ways. The Canadian system is designed to cover only Canadian soils. The Canadian system dispenses with the sub-order hierarchical level. Solonetzic and Gleysolic soils are differentiated at the order level.


Clay is a finely-grained natural rock or soil material that combines one or more clay minerals with possible traces of quartz (SiO2), metal oxides (Al2O3 , MgO etc.) and organic matter. Geologic clay deposits are mostly composed of phyllosilicate minerals containing variable amounts of water trapped in the mineral structure. Clays are plastic due to particle size and geometry as well as water content, and become hard, brittle and non–plastic upon drying or firing. Depending on the soil's content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red.

Although many naturally occurring deposits include both silts and clay, clays are distinguished from other fine-grained soils by differences in size and mineralogy. Silts, which are fine-grained soils that do not include clay minerals, tend to have larger particle sizes than clays. There is, however, some overlap in particle size and other physical properties. The distinction between silt and clay varies by discipline. Geologists and soil scientists usually consider the separation to occur at a particle size of 2 µm (clays being finer than silts), sedimentologists often use 4–5 μm, and colloid chemists use 1 μm. Geotechnical engineers distinguish between silts and clays based on the plasticity properties of the soil, as measured by the soils' Atterberg limits. ISO 14688 grades clay particles as being smaller than 2 μm and silt particles as being larger.

Mixtures of sand, silt and less than 40% clay are called loam. Loam makes good soil and is used as a building material.


Diskagma ("disc-like fragment") is a genus of problematic fossil from a Paleoproterozoic (2200 million years old) paleosol from South Africa, and significant as the oldest likely eukaryote and earliest evidence for megascopic life on land.

Economy of Ferizaj

Ferizaj is a city and municipality in southern Kosovo, located 38 kilometers (24 mi) south of the capital city, Pristina. Ferizaj is the third most populated city in Kosovo, after Pristina and Prizren.

It is the administrative centre of the homonymous district. The central city postal code is 70 000, and the currency is euro (€).

Gumbo (disambiguation)

Gumbo is a spicy, hearty stew or soup.

Gumbo may also refer to:

Gumbo (mascot), the mascot dog of the New Orleans Saints

Gumbo, Missouri, a community in the United States

Gumbo (soil), heavy clay soil

Okra or gumbo, a flowering plant with edible green fruit

Gumbo!, a 1963 album by Pony Poindexter with Booker Ervin

Dr. John's Gumbo, an album by Dr. John

"Gumbo" (song), by the rock band Phish

Gumbo, a character in Gumby

Gumbo, the pet St. Bernard dog in EastEnders

Gumbo, the family name of the characters in Rose Is Rose

Gumbo, the code name for Adobe Flex 4

Black Gumbo is a Texan name for Vertisol

Index of soil-related articles

This is an index of articles relating to soil.

Indian Institute of Soil Science

The Indian Institute of Soil Science (acronym IISS) is an autonomous institute for higher learning, established under the umbrella of Indian Council of Agricultural Research (ICAR) by the Ministry of Agriculture, Government of India for advanced research in the field of soil sciences.


Juanacatlán (Spanish pronunciation: [xwanakaˈtlan]) is a town and municipio (municipality) in the central region of the Mexican state of Jalisco.

Lago de Camécuaro National Park

Lago de Camécuaro National Park is located east of the city of Zamora de Hidalgo in the municipality of Tangancícuaro in the state of Michoacán. The Park consists of 9.65 hectares (23.8 acres) of protected area including Camécuaro Lake which is supplied by a series of natural springs. The lake is popular due to crystal clear water and the beautiful vegetation that surrounds the lake. Even though the lake is relatively small, many photographers from all over Mexico come to take professional photographs that capture the parks picturesque views.

Polish Soil Classification

The Polish Soil Classification (Polish: Systematyka gleb Polski) is a soil classification system used to describe, classify and organize the knowledge about soils in Poland.

Poza Rica

Poza Rica (Spanish pronunciation: [ˈposa ˈrika]), formally: Poza Rica de Hidalgo is a city and its surrounding municipality in the Mexican state of Veracruz. Its name means "rich well", because it was a place known for its abundance of oil. In this century oil was discovered in the area. It has since been almost completely extracted. This has resulted in the decline of oil well exploration and drilling activities, though there are still many oil facilities.

The city shares borders with the municipalities of Papantla, Tihuatlán, and Coatzintla, and stands on Federal Highway 180. The archaeological zone of El Tajín is located approximately 15 kilometers (9.3 mi) from Poza Rica. The area is intensely tropical, with two popular beaches within one hour, Tuxpan, and Tecolutla, and one within 40 minutes east, Cazones. Mexico City is about 220 kilometers (140 mi) from Poza Rica.

Unlike most Mexican cities, it does not have old buildings because it is a new city founded officially on November 20, 1951. For that reason it has contemporary architecture with well-lined and designed streets with a modern look.

While the petroleum industry features heavily amongst the industrial landscape in Poza Rica, the city also has a wide variety of other industries with a large middle class. As one of the largest and most populous cities in Veracruz, Poza Rica is an important industrial and commercial center, and a central hub for several road transportation lines. The city has recently seen a lot of growth, with several shopping malls opening around the city. The city had an official population of 174,512 inhabitants and the municipality had 181,438 at the census of 2005. However, the Poza Rica metropolitan area, which includes the municipalities of Papantla, Tihuatlán, and Coatzintla, showed a total population of 458,330.

Richvale, California

For the town formerly of this name, see Richland, California.Richvale (also, Richland, Silbys Switch, Silsby) is a small census-designated place (population 244) in Butte County, California, US, south of Chico and west of Oroville. The primary crop grown in the area surrounding Richvale is rice, irrigated from the Oroville Dam on the Feather River. Several farmers in the area are known for organic farming. The population was 244 at the 2010 census.

Richvale is located at 39° 29' 38" North, 121° 44' 41" West, 108 feet (33 m) above sea level.

The ZIP Code is 95974. The community is inside area code 530.

Stuttgart (soil)

Stuttgart soil series is an officially designated state symbol, the State Soil of Arkansas.

Stuttgart soils are named for the City of Stuttgart in southeast Arkansas. They are used primarily for crops, mainly rice, soybeans, small grains, and corn. The Stuttgart area is also famous for its large fall and winter population of ducks and geese (Stuttgart bills itself as "The Rice and Duck Capital of the World"). These waterfowl feed heavily on the crops grown on the Stuttgart soils. Stuttgart soils have been mapped on about 200,000 acres (810 km2) in Arkansas.

The Stuttgart series consists of very deep, moderately well drained or somewhat poorly drained soils formed in silty and clayey alluvium. These level to gently sloping soils are on the Grand Prairie in the Lower Mississippi Valley. They are classified as alfisols, but their high content of montmorillonite puts them close to the vertisol class. Because of the surface layer of silt loam and slow permeability in the clayey subsoil, the soils are ideal for rice production.

USDA soil taxonomy

USDA soil taxonomy (ST) developed by United States Department of Agriculture and the National Cooperative Soil Survey provides an elaborate classification of soil types according to several parameters (most commonly their properties) and in several levels: Order, Suborder, Great Group, Subgroup, Family, and Series. The classification was originally developed by Guy Donald Smith, former director of the U.S. Department of Agriculture's soil survey investigations.

Zamora, Michoacán

Zamora de Hidalgo (Spanish pronunciation: [saˈmoɾa de i'dalɢo]) is a city in the Mexican state of Michoacán. The 2010 census population was 141,627. making it the third largest city in the state. The city is the municipal seat of Zamora Municipality, which has an area of 330.97 km² (127.79 sq mi) and includes many other smaller communities, the largest of which is Ario de Rayón (Ario Santa Mónica). The municipality's population is around 186,102, which makes it the second most populous urban area in the state.

The city of Zamora is an important economic center in the state and the most significant population center between the cities of Morelia and Guadalajara. The city is located on the Tarascan Plateau in the northwestern part of the state, at an elevation of 1,567 m (5,141 ft) above sea level. Zamora is surrounded by the fertile Tziróndaro Valley which is an important agricultural area that exports large amounts of produce to the United States.

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