Editing Histosol

{{Short description|Soil consisting primarily of organic materials}}
{{Infobox soil
|name=Histosol
|alternative_name=
|image=Histisol profile.jpg
|image_size=250px
|image_caption=A Histosol profile
|classification_system=[[World Reference Base for Soil Resources|WRB]], [[USDA soil taxonomy]], other
|profile=OC
|parent_material=[[Organic matter]]
|code=HS
|climate=[[subarctic climate|subarctic]], other
}}

[[File:HistosolWorld.jpg|thumb|upright=1.6|Histosols of the world]]

In both the [[World Reference Base for Soil Resources]] (WRB)<ref>{{Cite web|url = https://wrb.isric.org/files/WRB_fourth_edition_2022-12-18.pdf|title = World Reference Base for Soil Resources, fourth edition|author=IUSS Working Group WRB|year = 2022|publisher = International Union of Soil Sciences, Vienna}}</ref> and the [[USDA soil taxonomy]],<ref>{{Cite web|url = https://www.nrcs.usda.gov/sites/default/files/2022-09/Keys-to-Soil-Taxonomy.pdf|title = Keys to Soil Taxonomy 13th edition|author=Soil Survey Staff|year = 2022|publisher = USDA Natural Resources Conservation Service}}</ref> a '''Histosol''' is a [[soil]] consisting primarily of [[organic material]]s. They are defined as having {{convert|40|cm|in}} or more of organic soil material starting within 40 cm from the soil surface. In Soil Taxonomy, [[Gelisol]]s key out before Histosols, and in WRB, Histosols key out before [[Cryosol]]s. Therefore, organic [[permafrost]] soils belong to the Histosols in WRB (Cryic Histosols) and to the Gelisols (Histels) in Soil Taxonomy. 

Organic soil material has an organic carbon content (by [[weight]]) of 12 percent or more (Soil Taxonomy) or 20 percent or more (WRB). These materials include [[Muck (soil)|muck]] ([[sapric]] soil material), mucky peat (hemic soil material), or [[peat]] ([[fibric]] soil material). Many Histosols show aquic conditions or artificial drainage,<ref>{{cite web |url=http://www.dep.state.fl.us/water/wetlands/delineation/soilwatr.htm |title=Hydric Soils of Florida |work=Wetland Evaluation and Delineation Program |publisher=[[Florida Department of Environmental Protection]] |access-date=2009-02-24 |archive-date=2008-03-16 |archive-url=https://web.archive.org/web/20080316061138/http://www.dep.state.fl.us/water/wetlands/delineation/soilwatr.htm |url-status=dead }}</ref> some (Folists in Soil Taxonomy and Folic Histosols in WRB) developed under terrestrial conditions. Organic material and therefore Histosols have very low [[bulk density]]. Many are [[acidic]] and very deficient in major [[plant]] [[nutrient]]s, especially the [[raised bog]]s, which are saturated by rainwater and lack connection to nutrient-containing groundwater.

Histosols are known by various other names in other countries, such as [[peat]] or [[muck (soil)|muck]]. In the [[Australian Soil Classification]], Histosols are called Organosols.<ref>{{Cite web|url = http://www.clw.csiro.au/aclep/asc_re_on_line/or/orgasols.htm|title = Australian Soil Classification – Organosols|access-date = 8 February 2016|publisher = CSIRO|archive-date = 16 February 2016|archive-url = https://web.archive.org/web/20160216030616/http://www.clw.csiro.au/aclep/asc_re_on_line/or/orgasols.htm|url-status = dead}}</ref>

Histosols form whenever organic matter forms at a more rapid rate than it is destroyed. This occurs because of restricted [[drainage]] precluding [[aerobic decomposition]], and the remains of plants and [[animal]]s remain within the soil. Thus, Histosols are very important [[Ecology|ecologically]] because they, and [[Gelisols]], store large quantities of organic [[carbon]]. If accumulation continues for a long enough period, [[coal]] forms.

Most Histosols occur in [[Canada]], [[Scandinavia]], the [[West Siberian Plain]], [[Sumatra]], [[Borneo]] and [[New Guinea]]. Smaller areas are found in other parts of [[Europe]], the [[Russian Far East]] (chiefly in [[Khabarovsk Krai]] and [[Amur Oblast]]), [[Florida]] and other areas of permanent [[swamp]]land. [[Fossil]] Histosols are known from the earliest extensive land [[vegetation]] in the [[Devonian]].

Histosols are generally very difficult to cultivate because of the poor drainage and often low chemical [[Fertility (soil)|fertility]]. However, Histosols formed on very recent [[glacial]] lands can often be very productive when drained and produce high-grade [[pasture]] for [[dairying]] or [[beef cattle]]. They can sometimes be used for [[fruit]] if carefully managed, but there is a great risk of the organic matter becoming dry [[Powder (substance)|powder]] and eroding under the influence of drying [[wind]]s. A tendency towards shrinkage and [[Soil compaction|compaction]] is also evident with [[crop]]s.

Like [[Gelisols]], Histosols have greatly restricted use for [[civil engineering]] purposes because heavy [[structure]]s tend to subside in the wet soil.

In [[USDA soil taxonomy]], Histosols are subdivided into:
* '''Folists''' – Histosols that are not saturated with water for long periods of time during the year.
* '''Fibrists''' – Histosols that are primarily made up of only slightly decomposed organic materials, often called peat.
* '''Hemists''' – Histosols that are primarily made up of moderately decomposed organic materials.
* '''Saprists''' – Histosols that are primarily made up of highly decomposed organic materials, often called muck.
* '''Wassists''' - Histosols that have a field observable water table 2 cm or more above the soil surface for more than 21 hours of each day in all years.

== Taxonomy. Principal qualifiers==
Histosols are classified into: <ref>{{Cite web |last= |title=World reference base for soil resources 2014. International soil classification system for naming soils and creating legends for soil maps. Update 2015. FAO |url=https://openknowledge.fao.org/server/api/core/bitstreams/bcdecec7-f45f-4dc5-beb1-97022d29fab4/content}}</ref>

*Muusic/ Rockic/ Mawic
*Cryic
*Thionic
*Folic
*Floatic/ Subaquatic/ Tidalic
*Fibric/ Hemic/ Sapric
*Leptic
*Murshic/ Drainic
*Ombric/ Rheic
*Hyperskeletic/ Skeletic
*Andic
*Vitric
*Calcic
*Dystric/ Eutric

==See also==
*[[Acid sulfate soil]]
*[[Hydric soil]]
*[[Pedogenesis]]
*[[Pedology (soil study)]]
*[[Soil classification]]
*[[Soil type]]


== References ==
{{reflist}}
* {{cite web| url =http://soils.usda.gov/technical/classification/orders/histosols.html| title =Histosols| publisher =USDA-NRCS| access-date =2006-05-14| url-status =dead| archive-url =https://web.archive.org/web/20060509223440/http://soils.usda.gov/technical/classification/orders/histosols.html| archive-date =2006-05-09}}
* {{cite web| url =http://soils.ag.uidaho.edu/soilorders/histosols.htm| title =Histosols| publisher =University of Idaho| access-date =2006-05-14| archive-url =https://web.archive.org/web/20060901063659/http://soils.ag.uidaho.edu/soilorders/histosols.htm| archive-date =2006-09-01| url-status =dead}}

==Further reading==
* W. Zech, P. Schad, G. Hintermaier-Erhard: Soils of the World. Springer, Berlin 2022, Chapter 3.3.1. {{ISBN|978-3-540-30460-9}}

== External links ==
* [https://wrb.isric.org/picture-gallery/ profile photos (with classification)] WRB homepage
* [https://www.iuss.org/index.php?article_id=73|title=IUSS profile photos (with classification)] IUSS World of Soils

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

[[Category:Pedology]]
[[Category:Types of soil]]