Chernozem (from rus, чернозём, p=tɕɪrnɐˈzʲɵm, r=chernozyom; "black ground"), also called black soil, is a black-colored soil containing a high percentage of

humus In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the Latin ...

(4% to 16%) and high percentages of phosphorus and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

compounds. Chernozem is very fertile soil and can produce high

agricultural yield In agriculture, the yield is a measurement of the amount of a crop grown, or product such as wool, meat or milk produced, per unit area of land. The seed ratio is another way of calculating yields. Innovations, such as the use of fertilizer, the c ...

s with its high moisture storage capacity. Chernozems are a Reference Soil Group of the

World Reference Base for Soil Resources The World Reference Base for Soil Resources (WRB) is an international soil classification system for naming soils and creating legends for soil maps. The currently valid version is the fourth edition 2022. It is edited by a working group of the Int ...

(WRB).

Distribution

The name comes from the Russian terms for black and soil, earth or land (''chorny'' + ''zemlya''). The soil, rich in organic matter presenting a black color, was first identified by Russian geologist Vasily Dokuchaev in 1883 in the tallgrass steppe or prairie of European Russia. Chernozem cover about 230 million

hectares The hectare (; SI symbol: ha) is a non-SI metric unit of area equal to a square with 100-metre sides (1 hm2), or 10,000 m2, and is primarily used in the measurement of land. There are 100 hectares in one square kilometre. An acre is ...

of land. There are two "chernozem belts" in the world. One is the Eurasian steppe which extends from eastern Croatia ( Slavonia), along the Danube (northern Serbia, northern

Bulgaria Bulgaria (; bg, България, Bǎlgariya), officially the Republic of Bulgaria,, ) is a country in Southeast Europe. It is situated on the eastern flank of the Balkans, and is bordered by Romania to the north, Serbia and North Maced ...

( Danubian Plain), southern and eastern Romania ( Wallachian Plain and

Moldavian Plain Moldavian Plain ( ro, Câmpia Moldovei) is a geographic area in the north east of Romania, one of the components of the Moldavian Plateau. Despite the name, Moldavian Plain is not flat, but a region dotted with hills, part of the Moldavian Plateau ...

), and

Moldova Moldova ( , ; ), officially the Republic of Moldova ( ro, Republica Moldova), is a Landlocked country, landlocked country in Eastern Europe. It is bordered by Romania to the west and Ukraine to the north, east, and south. The List of states ...

, to northeast Ukraine across the

Central Black Earth Region The Central Black Earth Region, Central Chernozem Region or ''Chernozemie'' (russian: Центрально-черноземная область, Центральная черноземная область, Центрально-черноз ...

of Central Russia, southern Russia into Siberia. The other stretches from the

Canadian Prairies The Canadian Prairies (usually referred to as simply the Prairies in Canada) is a region in Western Canada. It includes the Canadian portion of the Great Plains and the Prairie Provinces, namely Alberta, Saskatchewan, and Manitoba. These provin ...

in Manitoba through the Great Plains of the US as far south as Kansas. Similar soil types occur in Texas and Hungary. Chernozem layer thickness may vary widely, from several centimetres up to 1.5 metres (60 inches) in Ukraine, as well as the

Red River Valley The Red River Valley is a region in central North America that is drained by the Red River of the North; it is part of both Canada and the United States. Forming the border between Minnesota and North Dakota when these territories were admitted ...

region in the Northern US and Canada (location of the prehistoric

Lake Agassiz Lake Agassiz was a large glacial lake in central North America. Fed by glacial meltwater at the end of the last glacial period, its area was larger than all of the modern Great Lakes combined. First postulated in 1823 by William H. Keating, i ...

). The terrain can also be found in small quantities elsewhere (for example, on 1% of Poland). It also exists in Northeast China, near Harbin. The only true chernozem in Australia is located around Nimmitabel, with some of the richest soils in the nation. Previously, there was a

black market A black market, underground economy, or shadow economy is a clandestine market or series of transactions that has some aspect of illegality or is characterized by noncompliance with an institutional set of rules. If the rule defines the s ...

for the soil in Ukraine. The sale of agricultural land has been illegal in Ukraine since 1992 until the ban was lifted in 2020, but the soil, transported by truck, was able to be sold and bought. According to

Kharkiv Kharkiv ( uk, Ха́рків, ), also known as Kharkov (russian: Харькoв, ), is the second-largest city and municipality in Ukraine.

-based "Green Front" NGO, the black market for illegally acquired chernozem in Ukraine was projected to reach approximately US$900 million per year in 2011.

Canadian and United States soil classification

Chernozemic soils are a

soil type A soil type is a taxonomic unit in soil science. All soils that share a certain set of well-defined properties form a distinctive soil type. Soil type is a technical term of soil classification, the science that deals with the systematic categoriz ...

in the

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-orde ...

and the

History

Theories of Chernozem origin: * 1761:

Johan Gottschalk Wallerius Johan Gottschalk Wallerius (11 July 1709 – 16 November 1785) was a Swedish chemist and mineralogist. Biography Wallerius was born at Stora Mellösa in Närke (now Örebro County), Sweden. He was a son of provost Erik Nilsson Wallerius and h ...

(plant decomposition) * 1763: Mikhail Lomonosov (plant and animal decomposition) * 1799:

Peter Simon Pallas Peter Simon Pallas FRS FRSE (22 September 1741 – 8 September 1811) was a Prussian zoologist and botanist who worked in Russia between 1767 and 1810. Life and work Peter Simon Pallas was born in Berlin, the son of Professor of Surgery Si ...

(reeds marsh) * 1835:

Charles Lyell Sir Charles Lyell, 1st Baronet, (14 November 1797 – 22 February 1875) was a Scottish geologist who demonstrated the power of known natural causes in explaining the earth's history. He is best known as the author of ''Principles of Geolo ...

(loess) * 1840: Sir Roderick Murchison (weathered from Jurassic marine shales) * 1850:

Karl Eichwald ), present-day Latvia , death_date = , death_place = St. Petersburg, Russia , citizenship = Russian Empire , nationality = Baltic German , fields = GeologyMedicine , workplaces = Kazan University, Vi ...

(peat) * 1851: А. Petzgold (swamps) * 1852: Nikifor Borisyak (peat) * 1853: Vangengeim von Qualen (silt from northern swamps) * 1862: Rudolf Ludwig (bog on place of forests) * 1866:

Franz Josef Ruprecht Franz Josef Ruprecht (1 November 1814 – 4 April 1870) was an Austrian-born physician and botanist active in the Russian Empire, where he was known as Frants Ivanovič Ruprekht (russian: link=no, Франц Ива́нович Ру́прехт). ...

(decomposed steppe grasses) * 1879: First chernozem papers translated from Russian * 1883: Vasily Dokuchaev published his book ''Russian Chernozem'' with a complete study of this soil in European Russia. * 1929: Otto Schlüter (man-made) * 1999: Michael W. I. Schmidt (neolithic biomass burning) As seen in the list above, the 19th and 20th-century discussions on the pedogenesis of Chernozem originally stemmed from climatic conditions from the early Holocene to roughly 5500 BC. However, no single paleo-climate reconstruction could accurately explain geochemical variations found in Chernozems throughout central Europe. Evidence of anthropomorphic origins of stable pyrogenic carbon in Chernozem led to improved formation theories. Vegetation burning could explain Chernozem's high magnetic susceptibility, the highest of the major soil types. Soil magnetism increases when soil minerals

goethite Goethite (, ) is a mineral of the diaspore group, consisting of iron(III) oxide-hydroxide, specifically the "α" polymorph. It is found in soil and other low-temperature environments such as sediment. Goethite has been well known since ancient t ...

and

ferrihydrite Ferrihydrite (Fh) is a widespread hydrous ferric oxyhydroxide mineral at the Earth's surface, and a likely constituent in extraterrestrial materials. It forms in several types of environments, from freshwater to marine systems, aquifers to hy ...

convert to maghemite on exposure to heat. Temperatures sufficient to elevate maghemite on a landscape scale indicates the influence of fire. Given the rarity of such natural phenomenon in the modern-day, magnetic susceptibility in Chernozem likely relates to

control of fire by early humans The control of fire by early humans was a critical technology enabling the evolution of humans. Fire provided a source of warmth and lighting, protection from predators (especially at night), a way to create more advanced hunting tools, and a ...

Humification In classical soil science, humus is the dark organic matter in soil that is formed by the decomposition of plant and animal matter. It is a kind of soil organic matter. It is rich in nutrients and retains moisture in the soil. Humus is the La ...

can darken soils (

melanization Melanin (; from el, μέλας, melas, black, dark) is a broad term for a group of natural pigments found in most organisms. Eumelanin is produced through a multistage chemical process known as melanogenesis, where the oxidation of the amino ...

) absent a pyrogenic carbon component. Given the symphony of pedogenic processes that contribute to the formation of dark earth, the term Chernozem summarizes different types of black soils with the same appearance but different formation histories.

Notes

References

* IUSS Working Group WRB: World Reference Base for Soil Resources, fourth edition. International Union of Soil Sciences, Vienna 2022.

.

External links

profile photos (with classification)
WRB homepage
IUSS profile photos (with classification)
IUSS World of Soils {{Authority control Canadian Prairies Geology of Canada Geology of Russia Geology of the United States Geology of Ukraine Great Plains Pedology Types of soil