Hydric soil

Hydric soil is soil which is permanently or seasonally saturated by water, resulting in anaerobic conditions, as found in wetlands.


Most soils are aerobic. This is important because plant roots respire (that is, they consume oxygen and carbohydrates while releasing carbon dioxide) and there must be sufficient air—especially oxygen—in the soil to support most forms of soil life. Air normally moves through interconnected pores by forces such as changes in atmospheric pressure, the flushing action of rainwater, and by simple diffusion.

In addition to plant roots, most forms of soil microorganisms need oxygen to survive. This is true of the more well-known soil animals as well, such as ants, earthworms and moles. But soils can often become saturated with water due to rainfall and flooding. Gas diffusion in soil slows (some 10,000 times slower) when soil becomes saturated with water because there are no open passageways for air to travel. When oxygen levels become limited, intense competition arises between soil life forms for the remaining oxygen. When this anaerobic environment continues for long periods during the growing season, quite different biological and chemical reactions begin to dominate, compared with aerobic soils. In soils where saturation with water is prolonged and is repeated for many years, unique soil properties usually develop that can be recognized in the field. Soils with these unique properties are called hydric soils, and although they may occupy a relatively small portion of the landscape, they maintain important soil functions in the environment.[1]

The plants found in hydric soils often have aerenchyma, internal spaces in stems and rhizomes, that allow atmospheric oxygen to be transported to the rooting zone.[2] Hence, many wetlands are dominated by plants with aerenchyma;[3] common examples include cattails, sedges and water-lilies.

Technical definitions

United States

A hydric soil is defined by federal law[4] to mean "soil that, in its undrained condition, is saturated, flooded, or ponded long enough during a growing season to develop an anaerobic condition that supports the growth and regeneration of hydrophytic vegetation". This term is part of the legal definition of a wetland included in the United States Food Security Act of 1985 (P.L. 99-198). This definition is provided in the controlling regulations to the Wetland Conservation Provisions of the FSA of 1985(7 C.F.R 12) and is used by the U.S.D.A. Natural Resources Conservation Service in the administration of the Wetland Conservation Compliance provisions ("Swampbuster") contained in the FSA of 1985. In adopting this definition in 1985, Congress attempted to capture the duration of waterlogged condition of a hydric soil by adding that a hydric soil is waterlogged long enough to support not only the growth of plants adapted to life in anaerobic conditions but also the regeneration of such plants.

Another common definition of a hydric soils is provided by the National Technical Committee of Hydric Soils (NTCHS) as "a soil that formed under conditions of saturation, flooding, or ponding long enough during the growing season to develop anaerobic conditions in the upper part."[5] The NTCHS hydric soil definition is used by the U.S. Army Corps of Engineers and the Environmental Protection Agency in their joint responsibilities in the administration of Section 404 of the Clean Water Act (1972).

See also


  1. ^ Schuyt, K. and Brander, L. 2004. Living Waters: Conserving the Source of Life – The Economic Values of theWorld’sWetlands. Amsterdam, the Netherlands: European Union, and Gland, Switzerland: World Wildlife Fund.
  2. ^ Justin, S. H. F. W. and Armstrong, W. 1987. The anatomical characteristics of roots and plant response to soil flooding. New Phytologist 106: 465–95.
  3. ^ Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK.
  4. ^ Food Security Act(FSA) of 1985 16 U.S.C. Section 3801(a)(2)
  5. ^ This definition (Federal Register, July 13, 1994) replaced the older 1991 version and accomplished two things. First, a soil that is artificially drained or protected (ditches, levees, etc.) is a hydric soil if the soil in its undisturbed state meets the definition of a hydric soil. Estimated soil properties for manipulated soils are based on best professional estimates of the properties thought to exist before manipulation. Second, the link between the definition and criteria was removed.


  • Environmental Laboratory. 1987. Corps of Engineers Wetland Delineation Manual, Technical Report Y-87-1, U.S. Army Engineer Waterways Experiment Station, Vicksburg, Miss. Url (pdf) last accessed 2006-04-16
  • Soil Conservation Service. 1994. National Food Security Act Manual. Title 180. USDA Soil Conservation Service, Washington, D.C.
  • Soil Survey Staff. 1999. Soil Taxonomy: A Basic System of Soil Classification for Making and Interpreting Soil Surveys. USDA Natural Resources Conservation Service, Agric. Hdbk. 436, U.S. Government Printing Office, Washington, D.C. 869 pp.
  • Soil Survey Staff. 1994. National Soil Survey Handbook. USDA Soil Conservation Service, Washington, D.C.

External links

Arthrobacter paludis

Arthrobacter paludis is a Gram-positive, non-endospore-forming and strictly aerobic bacterium from the genus of Arthrobacter which has been isolated from hydric soil from the Seogmo Island in Korea.

Fish pond

A fish pond, or fishpond, is a controlled pond, artificial lake, or reservoir that is stocked with fish and is used in aquaculture for fish farming, or is used for recreational fishing or for ornamental purposes. In the medieval European era it was typical for monasteries and castles (small, partly self-sufficient communities) to have a fish pond.


Gley may refer to:

Eugène Gley (1857–1930), French physiologist and endocrinologist

Gley soil, a type of hydric soil


A Gley (Russian: глей) is a wetland soil (hydric soil) that, unless drained, is saturated with groundwater for long enough periods to develop a characteristic gleyic colour pattern. This pattern is essentially made up of reddish, brownish or yellowish colours at surfaces of soil particles (peds) and/or in the upper soil horizons mixed with greyish/blueish colours inside the peds and/or deeper in the soil. Gleysols are also known as Gleyzems and meadow soils (Russia), Aqu-suborders of Entisols, Inceptisols and Mollisols (USDA soil taxonomy), or as groundwater soils and hydro-morphic soils.

Gleysols occur on wide range of unconsolidated materials, mainly fluvial, marine and lacustrine sediments of Pleistocene or Holocene age, with basic to acidic mineralogy. They are found in depression areas and low landscape positions with shallow groundwater.

Wetness is the main limitation of virgin Gleysols; these are covered with natural swamp vegetation and lie idle or are used for extensive grazing. Artificially drained Gleysols are used for arable cropping, dairy farming and horticulture. Gleysols in the tropics and subtropics are widely planted to rice.

Gleysols occupy an estimated 720 million hectares worldwide. They are azonal soils and occur in nearly all climates. The largest extent of Gleysols is in northern Russia, Siberia, Canada, Alaska, China and Bangladesh. An estimated 200 million hectares of Gleysols are found in the tropics, mainly in the Amazon region, equatorial Africa and the coastal swamps of Southeast Asia.

They exhibit a greenish-blue-grey soil color due to anoxic wetland conditions. On exposure, as the iron in the soil oxidizes colors are transformed to a mottled pattern of reddish, yellow or orange patches. During soil formation (gleying), the oxygen supply in the soil profile is restricted due to soil moisture at saturation. Anaerobic micro-organisms support cellular respiration by using alternatives to free oxygen as electron acceptors to support cellular respiration. Where Anaerobic organisms reduce ferric oxide to ferrous oxide, the reduced mineral compounds produce the gley soil typical color. Green rust, a layered double hydroxide (LDH) of Fe(II) and Fe(III) can be found as the mineral fougerite in gley soils.

Gley soils may be sticky and hard to work, especially where the gleying is caused by surface water, held up on a slowly permeable layer. However, some ground-water gley soils have permeable lower horizons, including some sands, for example in hollows within sand dune systems, known as slacks, and in some alluvial situations.

Groundwater gley soils develop where drainage is poor because the water table (phreatic surface) is high, whilst Surface-water gleying occurs when precipitation inputs at the surface do not drain freely through the ground. A reducing environment exists in the saturated layers, which become mottled greyish-blue or brown because of the content of ferrous iron and organic matter. The presence of reddish or orange mottles indicates localised re-oxidation of ferrous salts in the soil matrix, and is often associated with root channels, animal burrows or cracking of the soil material during dry spells.

In the World Reference Base for Soil Resources (WRB), soils with redox processes due to ascending groundwater belong to the Reference Soil Group Gleysols. Soils with redox processes due to stagnant water are Stagnosols and Planosols.


In both the World Reference Base for Soil Resources (WRB) and the USDA soil taxonomy, a Histosol is a soil consisting primarily of organic materials. They are defined as having 40 centimetres (16 in) or more of organic soil material in the upper 80 centimetres (31 in). Organic soil material has an organic carbon content (by weight) of 12 to 18 percent, or more, depending on the clay content of the soil. These materials include muck (sapric soil material), mucky peat (hemic soil material), or peat (fibric soil material). Aquic conditions or artificial drainage are required. Typically, Histosols have very low bulk density and are poorly drained because the organic matter holds water very well. Most are acidic and many are very deficient in major plant nutrients which are washed away in the consistently moist soil.

Histosols are known by various other names in other countries, such as peat or muck. In the Australian Soil Classification, Histosols are called Organosols.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 animals remain within the soil. Thus, Histosols are very important 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 swampland. 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. 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 and eroding under the influence of drying winds. A tendency towards shrinkage and compaction is also evident with crops.

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

In USA 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.

Index of soil-related articles

This is an index of articles relating to soil.


A pond is an area filled with water, either natural or artificial, that is smaller than a lake. It may arise naturally in floodplains as part of a river system, or be a somewhat isolated depression (such as a kettle, vernal pool, or prairie pothole). It may contain shallow water with marsh and aquatic plants and animals.Factors impacting the type of life found in a pond include depth and duration of water level, nutrient level, shade, presence or absence of inlets and outlets, effects of grazing animals, and salinity.Ponds are frequently man-made, or expanded beyond their original depth and bounds. Among their many uses, ponds provide water for agriculture and livestock, aid in habitat restoration, serve as fish hatcheries, are components of landscape architecture, may store thermal energy as solar ponds, and treat wastewater as treatment ponds.

Ponds may be fresh, saltwater, or brackish.

Riparian zone

A riparian zone or riparian area is the interface between land and a river or stream. Riparian is also the proper nomenclature for one of the terrestrial biomes of the Earth. Plant habitats and communities along the river margins and banks are called riparian vegetation, characterized by hydrophilic plants. Riparian zones are important in ecology, environmental resource management, and civil engineering because of their role in soil conservation, their habitat biodiversity, and the influence they have on fauna and aquatic ecosystems, including grasslands, woodlands, wetlands, or even non-vegetative areas. In some regions the terms riparian woodland, riparian forest, riparian buffer zone, riparian corridor and riparian strip are used to characterize a riparian zone. The word riparian is derived from Latin ripa, meaning river bank.

Saline Wetlands Conservation Partnership

Saline Wetlands Conservation Partnership (SWCP) is a conservation program devoted to the protection and preservation of Nebraska’s Eastern Saline Wetlands. The Eastern Saline Wetlands of Lancaster and Saunders counties Nebraska are among the most unusual and threatened wetland communities in the state. Limited to the floodplain swales and depressions within the Salt Creek, Little Salt Creek, and Rock Creek drainages, it’s estimated that the Eastern Saline Wetlands once covered an area in excess of 200,000 acres (810 km2). Today, due to extensive degradation, draining and filling through commercial, residential, and agricultural development, less than 4,000 acres (16 km2) remain, and many of these remnants are highly degraded. Now more than ever it’s become increasingly important to preserve what remains of this unique wetland resource. Although several existing programs have been recognized to address saline wetland conservation needs, they alone have not been enough to ensure the long term protection of this endangered resource. Thus, the Saline Wetland Conservation Partnership (SWCP) was created to offer additional protection and management of the state’s diminishing saline wetlands.

Soil classification

Soil classification deals with the systematic categorization of soils based on distinguishing characteristics as well as criteria that dictate choices in use.

Stew pond

The Beef Stew Boyz were an American rock band formed in Franklin, New Hampshire in 2014. The most consistent line-up consisted of founding members Herb "Hump" Klayton (keyboards, vocals), Jojo Tyrn (bass guitar, trombone, vocals), Ian Mcgowney (lead guitar), Sam Jones (Drums, backing vocals) and Gregory Allen (saxophone). Earlier versions of the band included Kensley Smith on lead guitar and Josh Norton on drums. The band is one of the most influential in history, with 13 platinum albums and is considered the main influence in the "Rock Revolution" of the early 2020s. Led by Hump, the band found early online success on such online music-sharing platforms as Soundcloud and Musicpoop. They released several songs and an informal version of their first album "Beef Stew" here, before signing with Pickle Records and receiving critical and commercial acclaim for Beef Stew (2015). The band toured New England and the mid-western United States excessively for the next three years, becoming a major force in the Cowpunk scene. They released four more albums before obtaining superstar success in the 2020s: Beef Stew II (2016), concept album The Revenge of Pippi Longstocking (2016), Christmas (2017) and Beef Stew Boyz Now! (2018).

In July of 2018, the Boyz performed at the Cambridge Music Festival, or Bridgefest, and caught the eye of successful manager Jonathan "Grabby" Chabby and audience member Keith Richards. They would open for the Rolling Stones on tour the next year, promoting their latest album Beef Stew III, and making acoustic hit "Satan and the Fool" a college and mainstream radio favorite. In their prime (2019-2025), the Boyz would spawn another 9 number-one singles on the Billboard Hot 100 and seven more studio albums. Their album Barrel-chested Hellbound Caravan (2019) experimented in abrasive bass guitar and new diharmonic chord techniques, while bringing the group greater commercial success. Cover album We've Got You Covered (2019) and Mirrors (2022) also contained tracks and themes favored by many Beef Stew Boyz fans, or Beefies. After the first months of production for possible rock opera Beefworld, in 2025, Sam Jones and Gregory Allen left the band, to be replaced by Elvis Presto on drums. The band has toured consistently since then, in the U. S. and Canada but lacked major commercial success.

The band has received numerous awards, including five Grammy Awards, and two Ivor Novello Awards. They are consistently considered one of music's most influential artists, and the foremost musical influence of the 21st century.

Wade Hurt

G. Wade Hurt is a soil scientist in the United States and an authority on hydric soils. As of 2007, he has a position with the University of Florida's Soil and Water Science Department in Gainesville.

Hurt retired from the Natural Resources Conservation Service (NRCS) in 2007. He served as NRCS National Leader for Hydric Soils. Wade received his bachelor's degree from Mississippi State University.


A wetland is a distinct ecosystem that is inundated by water, either permanently or seasonally, where oxygen-free processes prevail. The primary factor that distinguishes wetlands from other land forms or water bodies is the characteristic vegetation of aquatic plants, adapted to the unique hydric soil. Wetlands play a number of functions, including water purification, water storage, processing of carbon and other nutrients, stabilization of shorelines, and support of plants and animals. Wetlands are also considered the most biologically diverse of all ecosystems, serving as home to a wide range of plant and animal life. Whether any individual wetland performs these functions, and the degree to which it performs them, depends on characteristics of that wetland and the lands and waters near it. Methods for rapidly assessing these functions, wetland ecological health, and general wetland condition have been developed in many regions and have contributed to wetland conservation partly by raising public awareness of the functions and the ecosystem services some wetlands provide.Wetlands occur naturally on every continent. The main wetland types are swamp, marsh, bog, and fen; sub-types include mangrove forest, carr, pocosin, floodplains, mire, vernal pool, sink, and many others. Many peatlands are wetlands. The water in wetlands is either freshwater, brackish, or saltwater.

Wetlands can be tidal (inundated by tides) or non-tidal. The largest wetlands include the Amazon River basin, the West Siberian Plain, the Pantanal in South America, and the Sundarbans in the Ganges-Brahmaputra delta.The UN Millennium Ecosystem Assessment determined that environmental degradation is more prominent within wetland systems than any other ecosystem on Earth.Constructed wetlands are used to treat municipal and industrial wastewater as well as stormwater runoff. They may also play a role in water-sensitive urban design.

Classification systems

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