Chernozem ( ),; also called black soil, regur soil or black cotton soil, is a black-colored

soil Soil, also commonly referred to as earth, is a mixture of organic matter, minerals, gases, water, and organisms that together support the life of plants and soil organisms. Some scientific definitions distinguish dirt from ''soil'' by re ...

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 Lati ...

(4% to 16%) and high percentages of

phosphorus Phosphorus is a chemical element; it has Chemical symbol, symbol P and atomic number 15. All elemental forms of phosphorus are highly Reactivity (chemistry), reactive and are therefore never found in nature. They can nevertheless be prepared ar ...

and

ammonia Ammonia is an inorganic chemical compound of nitrogen and hydrogen with the chemical formula, formula . A Binary compounds of hydrogen, stable binary hydride and the simplest pnictogen hydride, ammonia is a colourless gas with a distinctive pu ...

compounds. Chernozem is very fertile soil and can produce high agricultural yields with its high moisture-storage capacity. Chernozems are a Reference Soil Group of the World Reference Base for Soil Resources (WRB).

Distribution

The name comes from the Russian terms for black (чёрный ''čjornyj'') and soil, earth or land (земля ''zemlja''). Studies of the

steppe In physical geography, a steppe () is an ecoregion characterized by grassland plains without closed forests except near rivers and lakes. Steppe biomes may include: * the montane grasslands and shrublands biome * the tropical and subtropica ...

soils of the Poltava region in the

Russian Empire The Russian Empire was an empire that spanned most of northern Eurasia from its establishment in November 1721 until the proclamation of the Russian Republic in September 1917. At its height in the late 19th century, it covered about , roughl ...

in 1883, conducted by geologist Vasily Dokuchaev, showed that the peasants called all soils by color, so the scientist began to use such names. Chernozem was black in color due to the large amount of organic matter. Dokuchaev was the first to describe the chernozem of the European part of the Russian Empire, and discovered its fertility. It is distinct from the similar

terra preta ''Terra preta'' (, literally "black soil" in Portuguese language, Portuguese), also known as Amazonian dark earth or Indian black earth, is a type of very dark, fertile human impact on the environment, anthropogenic soil (anthrosol) found in the ...

of the

Amazon rainforest The Amazon rainforest, also called the Amazon jungle or Amazonia, is a Tropical and subtropical moist broadleaf forests, moist broadleaf tropical rainforest in the Amazon biome that covers most of the Amazon basin of South America. This basin ...

. Chernozem covers about 230 million

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

s of land. There are two "chernozem belts" in the world. One is the

Eurasian Steppe The Eurasian Steppe, also called the Great Steppe or The Steppes, is the vast steppe ecoregion of Eurasia in the temperate grasslands, savannas and shrublands biome. It stretches through Manchuria, Mongolia, Xinjiang, Kazakhstan, Siberia, Europea ...

that extends from eastern

Croatia Croatia, officially the Republic of Croatia, is a country in Central Europe, Central and Southeast Europe, on the coast of the Adriatic Sea. It borders Slovenia to the northwest, Hungary to the northeast, Serbia to the east, Bosnia and Herze ...

(

Slavonia Slavonia (; ) is, with Dalmatia, Croatia proper, and Istria County, Istria, one of the four Regions of Croatia, historical regions of Croatia. Located in the Pannonian Plain and taking up the east of the country, it roughly corresponds with f ...

), along the

Danube The Danube ( ; see also #Names and etymology, other names) is the List of rivers of Europe#Longest rivers, second-longest river in Europe, after the Volga in Russia. It flows through Central and Southeastern Europe, from the Black Forest sou ...

(northern

Serbia , image_flag = Flag of Serbia.svg , national_motto = , image_coat = Coat of arms of Serbia.svg , national_anthem = () , image_map = , map_caption = Location of Serbia (gree ...

, northern

Bulgaria Bulgaria, officially the Republic of Bulgaria, is a country in Southeast Europe. It is situated on the eastern portion of the Balkans directly south of the Danube river and west of the Black Sea. Bulgaria is bordered by Greece and Turkey t ...

( Danubian Plain), southern and eastern

Romania Romania is a country located at the crossroads of Central Europe, Central, Eastern Europe, Eastern and Southeast Europe. It borders Ukraine to the north and east, Hungary to the west, Serbia to the southwest, Bulgaria to the south, Moldova to ...

( Wallachian Plain and Moldavian Plain), and

Moldova Moldova, officially the Republic of Moldova, is a Landlocked country, landlocked country in Eastern Europe, with an area of and population of 2.42 million. Moldova is bordered by Romania to the west and Ukraine to the north, east, and south. ...

, to northeast

Ukraine Ukraine is a country in Eastern Europe. It is the List of European countries by area, second-largest country in Europe after Russia, which Russia–Ukraine border, borders it to the east and northeast. Ukraine also borders Belarus to the nor ...

across the Central Black Earth Region of Central and Southern Russia into

Siberia Siberia ( ; , ) is an extensive geographical region comprising all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has formed a part of the sovereign territory of Russia and its predecessor states ...

. 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 ...

Manitoba Manitoba is a Provinces and territories of Canada, province of Canada at the Centre of Canada, longitudinal centre of the country. It is Canada's Population of Canada by province and territory, fifth-most populous province, with a population ...

through the

Great Plains The Great Plains is a broad expanse of plain, flatland in North America. The region stretches east of the Rocky Mountains, much of it covered in prairie, steppe, and grassland. They are the western part of the Interior Plains, which include th ...

of the United States as far south as Kansas. 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 region in the northern United States and Canada (location of the prehistoric Lake Agassiz). The terrain can also be found in small quantities elsewhere (for example, in 1% of Poland, Hungary, and Texas). It also exists in

Northeast China Northeast China () is a geographical region of China, consisting officially of three provinces Liaoning, Jilin and Heilongjiang. The heartland of the region is the Northeast China Plain, the largest plain in China with an area of over . The regi ...

, near

Harbin Harbin, ; zh, , s=哈尔滨, t=哈爾濱, p=Hā'ěrbīn; IPA: . is the capital of Heilongjiang, China. It is the largest city of Heilongjiang, as well as being the city with the second-largest urban area, urban population (after Shenyang, Lia ...

. The only true chernozem in Australia is located around Nimmitabel, some of the richest soils on the continent. Previously, there was a

black market A black market is a Secrecy, clandestine Market (economics), market or series of transactions that has some aspect of illegality, or is not compliant with an institutional set of rules. If the rule defines the set of goods and services who ...

for the soil in Ukraine. The sale of agricultural land was illegal in Ukraine from 1992 to 2020, but the soil, transported by truck, could be traded legally. According to the

Kharkiv Kharkiv, also known as Kharkov, is the second-largest List of cities in Ukraine, city 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 categ ...

in the Canadian system of soil classification and the World Reference Base for Soil Resources (WRB). Chernozemic soil type "equivalents", in the Canadian system, WRB, and U.S. Department of Agriculture soil taxonomy:

Theories of Chernozem origin

* 1761: Johan Gottschalk Wallerius (plant decomposition) * 1763:

Mikhail Lomonosov Mikhail Vasilyevich Lomonosov (; , ; – ) was a Russian polymath, scientist and writer, who made important contributions to literature, education, and science. Among his discoveries were the atmosphere of Venus and the law of conservation of ...

(plant and animal decomposition) * 1799:

Peter Simon Pallas Peter Simon Pallas Fellow of the Royal Society, FRS FRSE (22 September 1741 – 8 September 1811) was a Prussia, Prussian zoologist, botanist, Ethnography, ethnographer, Exploration, explorer, Geography, geographer, Geology, geologist, Natura ...

(reeds marsh) * 1835: Charles Lyell (loess) * 1840: Sir Roderick Murchison (weathered from Jurassic marine shales) * 1850: Karl Eichwald (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 (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 The Holocene () is the current geologic time scale, geological epoch, beginning approximately 11,700 years ago. It follows the Last Glacial Period, which concluded with the Holocene glacial retreat. The Holocene and the preceding Pleistocene to ...

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 hydro ...

convert to

maghemite Maghemite (Fe2O3, γ-Fe2O3) is a member of the family of iron oxides. It has the same formula as hematite, but the same spinel ferrite structure as magnetite () and is also ferrimagnetic. It is sometimes spelled as "maghaemite". ''Maghemite'' ...

on exposure to heat. Temperatures sufficient to elevate maghemite on a landscape scale indicate the influence of fire. Given the rarity of such natural phenomena 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 ...

. Humification can darken soils ( melanization) absent a pyrogenic carbon component. Given the symphony of pedogenic processes that contribute to the formation of dark earth, 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