Editing Chernozem

{{Short description|Soil type; fertile black-coloured soil}}
{{Use dmy dates|date=September 2023}}
{{Infobox soil
|name = Chernozem
|alternative_name = Chernozemic soil
|type = 
|type_link = 
|image = Image:Mollisol.jpg
|image_size = 250px
|image_caption = Mollisol ([[USDA]]-[[Natural Resources Conservation Service|NRCS]])
|classification_system = [[World Reference Base for Soil Resources|WRB]], other
|profile = AhBC
|parent_material = [[Loess]]
|code = CH
|climate = [[Humid continental climate|Humid continental]]
}}

'''Chernozem''' ({{IPAc-en|ˈ|tʃ|ɜːr|n|ə|z|ɛ|m}} {{respell|CHUR-nə-zem}}),{{efn|{{lang-rus|Чернозём|p=tɕɪrnɐˈzʲɵm|r=Černozjom}}; {{lit|black ground}}<ref>{{cite book|title=Russia Investment and Business Guide|date=2007|publisher=International Business Publications|isbn=9781433041686|page=63|url=https://books.google.com/books?id=BFC0zTM4TkAC&q=Chernozyom&pg=PA63|access-date=11 January 2018|language=en}}{{Dead link|date=May 2023 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref name=Etymonline>{{Cite web |title=chernozem {{!}} Etymology, origin and meaning of chernozem by etymonline |url=https://www.etymonline.com/word/chernozem |access-date=5 October 2022 |website=www.etymonline.com |language=en}}</ref>}} also called '''black soil''', '''regur soil''' or '''black cotton soil''', is a black-colored [[soil]] containing a high percentage of [[humus]]<ref name=Merriam-Webster>{{cite web    | url = http://www.merriam-webster.com/dictionary/chernozem  | title = Chernozem  | access-date = 7 July 2008| year = 2008 | work= Merriam-Webster Online Dictionary}}</ref> (4% to 16%) and high percentages of [[phosphorus]] and [[ammonia]] compounds.<ref>{{cite news |title=How Chemical Pre-Treatments in Particle Size Analysis Impact Wind Erosion Modeling |url=https://www.azom.com/article.aspx?ArticleID=20616 |access-date=30 August 2022 |work=AZoM.com |date=28 July 2021 |language=en}}</ref> Chernozem is very [[soil fertility|fertile]] soil and can produce high [[agricultural yield]]s with its high moisture-storage capacity.{{Efn|Prolonged use may still require replenishment with fertilizers because it easily can get depleted of nutrients.}} Chernozems are a Reference Soil Group of the [[World Reference Base for Soil Resources]] (WRB).

== Distribution ==
[[File:Chernozem map.svg|thumb|Distribution of chernozem soils according to the [[World Reference Base for Soil Resources]] classification:
{{legend|#d95f0e|Dominant (more than 50% of soil cover)}}
{{legend|#fec44f|Codominant (25–50%)}}
{{legend|#fff7bc|Associated (5–25%)}}]]
The name comes from the [[Russian language|Russian]] terms for black (чёрный ''čjornyj'') and soil, earth or land (земля ''zemlja'').<ref name=Etymonline/><ref name=Merriam-Webster/> The soil, rich in organic matter presenting a black color, was first identified by the [[Russians|Russian]] geologist [[Vasily Dokuchaev]] in 1883 in the tallgrass [[steppe]] or prairie of [[Eastern Ukraine]] and [[European Russia]]. It is distinct from the similar [[terra preta]] of the [[Amazon rainforest]].

Chernozem covers about 230 million [[hectare]]s of land. There are two "chernozem belts" in the world. One is the [[Eurasian Steppe]] that extends from eastern [[Croatia]] ([[Slavonia]]), along the [[Danube]] (northern [[Serbia]], northern [[Bulgaria]] ([[Danubian Plain (Bulgaria)|Danubian Plain]]), southern and eastern [[Romania]] ([[Wallachian Plain]] and [[Moldavian Plain]]), and [[Moldova]], to northeast [[Ukraine]] across the [[Central Black Earth Region]] of [[Central Russia|Central]] and [[Southern Russia]] into [[Siberia]]. The other stretches from the [[Canadian Prairies]] in [[Manitoba]] through the [[Great Plains]] of the United States as far south as Kansas.<ref>[https://books.google.com/books?id=GTHrCAAAQBAJ&dq=kansas+Chernozem+soil&pg=PA58 Ecology of Arable Land – Perspectives and Challenges] by M. Clarholm and L. Bergström {{ISBN|978-94-010-6950-2}}</ref> 

Chernozem layer thickness may vary widely, from several centimetres up to 1.5 metres (60 inches) in Ukraine,<ref>[http://www.britannica.com/EBchecked/topic/612921/Ukraine/30095/Soils Ukraine: Soils] in [[Encyclopædia Britannica]]</ref> 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]], near [[Harbin#Economy|Harbin]]. The only true chernozem in Australia is located around [[Nimmitabel]], some of the richest soils on the continent.<ref>KG McQueen. "[http://regolith.org.au/docs/cars/carspub2.pdf The Tertiary Geology And Geomorphology Of The Monaro: The Perspective In 1994]" Centre For Australian Regolith Studies, Canberra 1994</ref>

Previously, there was a [[black market]] for the soil in Ukraine. The sale of agricultural land was illegal in Ukraine from 1992 to 2020,<ref>{{cite web |title=Ukraine lifts ban on sale of farmland in bid to receive international funds |url=https://www.euronews.com/2020/03/31/ukraine-lifts-ban-on-sale-of-farmland-in-bid-to-receive-international-funds |website=Euronews |date=31 March 2020 }}</ref> but the soil, transported by truck, could be traded legally. According to the [[Kharkiv]]-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.<ref>[https://www.kyivpost.com/article/opinion/op-ed/black-market-for-rich-black-earth-116610.html Black market for rich black earth], [[Kyiv Post]] (9 November 2011)</ref>

== Canadian and United States soil classification ==
'''Chernozemic soils''' are a [[soil type]] in the [[Canadian system of soil classification]] and the [[World Reference Base for Soil Resources]] (WRB).

Chernozemic soil type "equivalents", in the Canadian system, [[World Reference Base for Soil Resources|WRB]], and [[USDA soil taxonomy|U.S. Department of Agriculture soil taxonomy]]:

{|
|-style="border-bottom:1px solid black;"
! align=left style="border-bottom:1px solid black;" | Canadian
! align=left style="border-bottom:1px solid black;" | WRB
! align=left style="border-bottom:1px solid black;" | United States
|-
| [http://www.soilsofcanada.ca/orders/chernozemic-soils.php Chernozemic]
| Kastanozem, Chernozem, Phaeozem
| [[Mollisol]]
|-
| Brown Chernozem
| Kastanozem (Aridic)
| Aridic Mollisol subgroups (Xerolls and Ustolls)
|-
| Dark Brown Chernozem
| Haplic Kastanozem
| Typic Mollisol subgroups
|-
| Black Chernozem
| Chernozem
| [[udic moisture regime|Udic]] Mollisol subgroups
|-
| Dark Grey Chernozem
| Greyzemic Phaeozem
| Boralfic Mollisol subgroups, Albolls
|-
|Source: [http://www.pedosphere.com/resources/cssc3rd/chapter16.html Pedosphere.com] {{Webarchive|url=https://web.archive.org/web/20160314065655/http://pedosphere.com/resources/cssc3rd/chapter16.html |date=14 March 2016 }}.
|}

== Theories of Chernozem origin ==
* 1761: [[Johan Gottschalk Wallerius]] (plant decomposition)<ref>Wallerius J. G. ''Agriculturae fundamenta chemica, åkerbrukets chemiska grunder''. Upsaliae, 1761. 8, 4, 322 p.; The natural and chemical elements of agriculture. London, York: Bell, Etherington, 1770. 198 p.</ref> 
* 1763: [[Mikhail Lomonosov]] (plant and animal decomposition)<ref>'Lomonosov M. V. § 125. // ''On the strata of the Earth: a translation of "O sloiakh zemnykh"'' (1763) / translated by S. M. Rowland, S. Korolev. Boulder: Geological Soc. of America, 2012. 41 p. (Special paper; 485) "And so, there is no doubt that black soil is not primordial matter, but that it has been produced by the decomposition of animal and plant bodies over time"</ref>
* 1799: [[Peter Simon Pallas]] (reeds marsh){{cn|date=July 2023}}
* 1835: [[Charles Lyell]] (loess)<ref name=Geik75>{{citation|title=Life of Sir Roderick I, Murchison|volume=1|first1=A. |last1=Geikie | year=1875 |asin=B0095632AU}}</ref>
* 1840: [[Sir Roderick Murchison]] (weathered from Jurassic marine shales)<ref name=Geik75/>  
* 1850: [[Karl Eichwald]] (peat){{cn|date=July 2023}} 
* 1851: А. Petzgold (swamps)
* 1852: Nikifor Borisyak (peat){{cn|date=July 2023}}
* 1853: Vangengeim von Qualen (silt from northern swamps) 
* 1862: Rudolf Ludwig (bog on place of forests){{cn|date=July 2023}}
* 1866: [[Franz Josef Ruprecht]] (decomposed steppe grasses) <ref>{{citation|title=The Origins of the Russian Chernozem Soil (Black Earth): Franz Joseph Ruprecht's 'Geo-Botanical Researches into the Chernozem' of 1866 |first1=Anastasia A. |last1=Fedotova |journal=Environment and History |volume=16|issue=3 |date=August 2010 |pages=271–293|jstor=20723789 |doi=10.3197/096734010x519762|url=http://www.environmentandsociety.org/node/7607 |url-access=subscription }}</ref>
* 1879: First chernozem papers translated from Russian<ref>''Dokoutchaief B.'' Tchernozème (terre noire) de la Russie d'Europe. St.-Ptb.: Soc. Imp. libre économ., 1879. 66 p. (Comptes-rendus Soc. Imp. libre économ. T. 4).</ref> 
* 1883: [[Vasily Dokuchaev]] published his book ''Russian Chernozem'' with a complete study of this soil in European Russia.<ref>''Dokuchaev V. V.'' Russian Chernozem (1883) // Israel Program for Scientific Translations Ltd. (for USDA-NSF), S. Monson, Jerusalem, 1967. (Translated from Russian into English by N. Kaner)</ref>
* 1929: [[Otto Schlüter]] (man-made)<ref name=eckm07>{{citation |first1=Eileen |last1=Eckmeier |first2=Renate |last2=Gerlach |first3=Ernst |last3=Gehrt |first4=Michael W.I. |last4=Schmidt |title=Pedogenesis of Chernozems in Central Europe—A review |journal=Geoderma |volume=139 |issue=3–4 |year=2007 |pages=288–299 |doi=10.1016/j.geoderma.2007.01.009 |url=http://www.geo.unizh.ch/~mschmidt/downloads/Eckmeier_Geoderma_2007.pdf |url-status=dead |archive-url=https://web.archive.org/web/20160308210844/http://www.geo.unizh.ch/~mschmidt/downloads/Eckmeier_Geoderma_2007.pdf |archive-date=8 March 2016  |bibcode=2007Geode.139..288E }}</ref>
* 1999: Michael W. I. Schmidt (neolithic biomass burning)<ref>{{citation|last1=Schmidt |first1=M.W.I. |last2=Skjemstad |first2=J.O. |last3=Jäger |first3=C. |year=2002 |title=Carbon isotope geochemistry and nanomorphology of soil black carbon: Black chernozemic soils in central Europe originate from ancient biomass burning |journal=Global Biogeochemical Cycles |volume=16 |issue=4 |doi=10.1029/2002GB001939 |quote=These data challenge the common paradigm that chernozems are zonal soils with climate, parent material and bioturbation dominating soil formation, and introduce fire as a novel, important factor in the formation of these soils |bibcode=2002GBioC..16.1123S |pages=70–1–70–8|s2cid=56045817 |doi-access=free }}</ref><ref>{{citation|last1=Eckmeier|first1=E.|title=Detecting prehistoric fire-based farming using biogeochemical markers|year=2007|publisher=University of Zurich, Faculty of Science.|doi=10.5167/uzh-3752|quote=It is now an open question as to whether Neolithic settlers did indeed prefer to grow crops where Chernozems occurred or if Neolithic burning formed the chernozemic soils. |url=http://www.zora.uzh.ch/3752|type=Dissertation}}</ref>

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 [[black carbon#Presence in soils|pyrogenic carbon]] in Chernozem led to improved formation theories.<ref name=eckm07/> Vegetation burning could explain Chernozem's high [[magnetic susceptibility]],<ref>{{citation |first1=Eileen |last1=Eckmeier |first2=Renate |last2=Gerlach |first3=Ernst |last3=Gehrt |first4=Michael W.I. |last4=Schmidt |title=Pedogenesis of Chernozems in Central Europe—A review |journal=Geoderma |volume=139 |issue=3–4 |year=2007 |pages=288–299 |doi=10.1016/j.geoderma.2007.01.009 |url=http://www.geo.unizh.ch/~mschmidt/downloads/Eckmeier_Geoderma_2007.pdf |url-status=dead |archive-url=https://web.archive.org/web/20160308210844/http://www.geo.unizh.ch/~mschmidt/downloads/Eckmeier_Geoderma_2007.pdf |archive-date=8 March 2016  |bibcode=2007Geode.139..288E |quote=magnetic susceptibility of soil material may reflect past fires}}</ref> the highest of the major soil types.<ref name="Jordanova">{{cite book|title=Soil Magnetism|editor-first=Neli|editor-last=Jordanova|year=2017|chapter=Chapter 8 - The discriminating power of soil magnetism for the characterization of different soil types
|chapter-url=https://www.sciencedirect.com/science/article/pii/B9780128092392000085
|pages=349–365|doi=10.1016/B978-0-12-809239-2.00008-5|isbn=978-0-12-809239-2|publisher=Academic Press|quote=Chernozem soils exhibit similar features worldwide and are generally characterized by significant magnetic enhancement in the upper soil horizons.}}</ref>  Soil magnetism increases when soil minerals [[goethite]] and [[ferrihydrite]] convert to [[maghemite]] on exposure to heat.<ref>{{Cite journal|url=https://pubs.geoscienceworld.org/claymin/article-abstract/39/1/85/56468/Mineralogy-of-a-burned-soil-compared-with-four?redirectedFrom=fulltext|doi = 10.1180/0009855043910122|title = Mineralogy of a burned soil compared with four anomalously red Quaternary deposits in Denmark|year = 2004|last1 = Nørnberg|first1 = P.|last2 = Schwertmann|first2 = U.|last3 = Stanjek|first3 = H.|last4 = Andersen|first4 = T.|last5 = Gunnlaugsson|first5 = H.P.|journal = Clay Minerals|volume = 39|issue = 1|pages = 85–98|bibcode = 2004ClMin..39...85N|s2cid = 129974901|url-access = subscription}}</ref> 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]].<ref name="Jordanova"/>

[[Humification]] can darken soils ([[melanization]]) absent a pyrogenic carbon component. Given the symphony of [[Pedogenesis|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.

== See also ==
* [[Loam]]
* [[Dark earth]]
* [[Terra preta]]
* [[Vertisol]]
* [[Mollisol]]
* [[Soil organic matter]]

== Notes ==
{{Notelist}}

== References ==
* IUSS Working Group WRB: World Reference Base for Soil Resources, fourth edition. International Union of Soil Sciences, Vienna 2022. {{ISBN|979-8-9862451-1-9}} ([https://wrb.isric.org/files/WRB_fourth_edition_2022-12-18.pdf]).

{{Reflist}}

==Further reading==
* W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the World. Springer, Berlin 2022, Chapter 5.3.2. {{ISBN|978-3-540-30460-9}}

== External links ==
{{Commons category|Chernozem}}
{{Wiktionary|chernozem}}
* [https://wrb.isric.org/picture-gallery/ profile photos (with classification)] WRB homepage
* [https://www.iuss.org/index.php?article_id=73 IUSS profile photos (with classification)] {{Webarchive|url=https://web.archive.org/web/20180909150525/https://www.iuss.org/index.php?article_id=73 |date=9 September 2018 }} IUSS World of Soils

{{Soil type}}
{{Authority control}}

[[Category:Canadian Prairies]]
[[Category:Geology of Canada]]
[[Category:Geology of Russia]]
[[Category:Geology of the United States]]
[[Category:Geology of Ukraine]]
[[Category:Great Plains]]
[[Category:Pedology]]
[[Category:Types of soil]]