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The 12 soil orders


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The 12 soil orders

  1. 1. 28/03/2011 1. ENTISOLSSoil Taxonomy Classification Sytem (‐ent) 1
  2. 2. 28/03/2011 Major soil property: featureless soil bodies Climate: ‐ may form in a variety of climates Diagnostic horizons: typically absent, albic Epipedon: ochric (light color due to limited  Examples accumulation of OM) 1. an arid or pergelic (cold) climate may limit the amount of Characteristic: little or no evidence of soil  p soil development to inhibit the formation of other soil development d l orders The Entisols are recent soils occuring on flood‐plains Pergelic = mean annual soil temperature is between‐4°C to ‐10°Cof large rivers or on other recent deposits. The recent 2. A pronounced saturation of the soil profile or evendeposits generally show stratification. submergence for long enough periods inhibit soil development Parent Material: 1. Entisols are on land surfaces that are very young (alluvium, colluvium, mudflows) 2
  3. 3. 28/03/2011Colluvium Parent Material: 2. extremely hard rocks (e.g. Orthents), or disturbed material (e.g. mined land, highly compacted soils, toxic material). 3. They also occur on deep bodies of water and glaciers which are transitions between soils and not soils . soils not soils Effect of gravity 3
  4. 4. 28/03/2011 Parent Material: 4. They are also typical of the shifting sands of the Sahara Desert and Saudi Arabia. Parent Material:5. In serpentine barrens (Serpentinite rocks), Entisols may be associated with bedrock outcrops.6. Entisols may be also associated with salt flats. 4
  5. 5. Million years ago (Ma) Era eon Epoch Period Supereon c.4570 Cryptic Era c.4150 Basin Groups c.3920 Nectarian Hadean c.3850 Lower Imbrian 3800 Eoarchean 3600 Paleoarchean 3200 Mesoarchean Archean 2800 Neoarchean 2500 Siderian 2300 Rhyacian Paleoproterozoic Precambrian 2050 Orosirian 1800 Statherian 1600 Calymmian 1400 Ectasian Mesoproterozoic Proterozoic 1200 Stenian 1000 Tonian 850 Cryogenian Neoproterozoic 630 +5/-30 Ediacaran 542.0 ± 1.0 Lo ower/Early 513.0 ± 2.0 Middle Cambrian Upp per/Late or 501.0 ± 2.0 - 496.0 ± 2.0 Furongian 488.3 ± 1.7 - 478.6 ± 1.7 wer/Early* Low 471.8 ± 1.6 - 468.1 ± 1.6 Middle* Ordovician* 460.9 ± 1.6 - 445.6 ± 1.5 Up pper/Late* 443.7 ± 1.5 - 436.0 ± 1.9 Lo ower/Early 428.2 ± 2.3 - 426.2 ± 2.4 W Wenlock Silurian 422.9 ± 2.5 - 421.3 ± 2.6 Up pper/Late 418.7 ± 2.7 Pridoli 416.0 ± 2.8 - 374.5 ± 2.6 Lo ower/Early Devonian Carboniferous Paleozoic Era (542 Ma - 252 Ma) 359.2 ± 2.5 - 326.4 ± 1.6 Mississipian* Carboniferous 318.1 ± 1.3 - 303.9 ± 0.9 Pennsylvanian* 299.0 ± 0.8 - 275.6 ± 0.7 C Cisuralian 270.6 ± 0.7 - 265.8 ± 0.7 Gu uadalupian Permian 260.4 ± 0.7 - 253.8 ± 0.7 L Lopingian Phanerozoic (542 Ma - present) 251.0 ± 0.7 - 203.6 ± 1.5 Triassic* 199.6 ± 0.6 - 150.8 ± 4.0 Jurassic* Ma) 145.5 ± 4.0 - 112.0 ± 1.0 Low wer/Early* Cretaceous (251 Ma - 65 Mesozoic Era 99.6 ± 0.9 - 70.6 ± 0.6 Up pper/Late* K-T Mass Extinction T 65.5 ± 0.3 - 58.7 ± 0.2 Pa aleocene T 55.8 ± 0.2 - 37.2 ± 0.1 Eocene T Paleogen 33.9 ± 0.1 - 28.4 ± 0.1 O Oligocene T 23.03 ± 0.05 - 7.246 ± 0.05 M Miocene T present) 5.332 ± 0.005 - 3.600 ± 0.005 P Pliocene Q 2.588 ± 0.005 - 0.126 ± 0.005 Ple eistocene Cenozoic Era (65 Ma- Neogene Q 0.011430 ± 0.00013 Ma - now Holocene (‐ept) Global distribution of Entisols 2. INCEPTISOLS5 28/03/2011
  6. 6. 28/03/2011 The subsoil in this soil is permanently under water. In the absence of oxygen a bluish color develops in the soil and is evidence for reduction The Inceptisols have horizons in early stage of formation. Inceptisols form under a variety of climates except aridicSome are wet soils and used for rice cultivation. Others may conditions.occur on slopes of hills or mountains. Soil moisture regimes can be variable ranging from poorly drained soils to well‐drained soils on steep slopes. Climate which inhibits soil development such as low temperatures or low precipitation favors the development of Inceptisols. The suborder of Aquepts requires higher soil moisture conditions compared to the other suborders of Inceptisols. 6
  7. 7. 28/03/2011 Global distribution of InceptisolsParent Material: Inceptisols are extensive in areas of glacial deposits or on recent deposits in valleys or deltas. They occupy upland positions on young geomorphic surfaces, both primary and secondary minerals are present. Most Inceptisols are present on geologically young sediments (e.g. alluvium, colluvium, loess). Parent materials which is highly calcareous or resistant to weathering inhibit soil development but favor the development of Inceptisols. 3. MOLLISOLS (‐oll) 7
  8. 8. 28/03/2011 The Mollisols are the Prairie soils. They have a dark surface horizon, very friable and easy to cultivate. The soil is generally deep and may have some special features. The white subsoil is due to the presence of a calcic horizonGlobal distribution of Mollisols 4. ALFISOLS (‐alf) 8
  9. 9. 28/03/2011 The Alfisols are well structured deep soils and generally very fertile. They support a good vegetation and in most parts of the world are used for agriculture. The ‘B’ horizon has well developed columnar structureGlobal distribution of Alfisols 5. ULTISOLS (‐ult) 9
  10. 10. 28/03/2011 The Ultisols are mainly in the humid parts of the world. They have a subsoil with more clay (or and argillic horizon) and are generally acid. Ultisol from Taiwan is a rice‐ growing soil and has reddish mottles called plinthite.Global distribution of Ultisols 6. OXISOLS (‐ox) 10
  11. 11. 28/03/2011 The Oxisols are found in the tropics, generally yellowish to reddish in color, deep, loamy to clayey, and the natural vegetation is forest.Global distribution of Oxisols 7. VERTISOLS (‐ert) 11
  12. 12. 28/03/2011 Characteristic feature of soils are slickensides , which are arranged in a curvi‐linear In Vietnam Vertisol structural polygons are exposed to the sun  to form seedbed material manner. Global distribution of Vertisols The Vertisols are formed on sediments rich insmectites (2:1 clay). Smectites swell when moist andshrink when dry and this property has implications forstructures built on this soil. 12
  13. 13. 28/03/20118. ANDISOLS (‐and) The Andisols develop on volcanic deposits under different climates. Many of them are stratified indicating different periods of pyroclastic deposition. A buried soil and there was a period of a few thousand years prior to the more recent deposition. During this period, vegetation was established and an organic rich surface horizon formed. 13
  14. 14. 28/03/2011Global distribution of Andisols 9. HISTOSOLS (‐ist) The Histosols are formed by accumulation of organic matter in a water‐logged basin or under a cold humid climate or both. from Greek  “Histos = tissue” “ i  i ” Formed under conditions of water saturation. Water stands in the pit. Histosols in Sumatra 14
  15. 15. 28/03/2011 comprises soils formed in ‘organic soil material’. These vary from soils developed in moss peatParent material: (boreal, arctic and subarctic regions), reeds/sedge incompletely decomposed plant remains, with peat and forest peat (temperate regions),or without admixtures of sand, silt or clay. mangrove peat and swamp forest peat (humid tropics). Found at all altitudes but the vast majority occurs‘Organic soil material’ is soil material that contains in lowlands.more than 20 percent organic matter by weight,roughly equivalent to 30 – 35 percent by volume. Common international names are ‘peat soils’, ‘muck soils’, ‘bog soils’ and ‘organic soils’. Elsewhere, they are confined to poorly drained The exceptionally large total pore volume of Histosols (typically > 85%), their perishable nature and their basins, depressions, swamps and marshlands with normally poor chemical properties pose formidable shallow groundwater, and highland areas with a problems to farmers and others concerned with conserving high precipitation/evapotranspiration ratio. use of Histosols. Organic soil materials that formed in different g Fibric Histosols are loosely p y packed in their natural state, environments are generally of different botanical with a bulk density (ρ) that is typically between 0.05 and composition; degrees of decomposition and 0.15 Mg/m3. contents of mineral admixtures are equally varied. Wide variation in chemical properties: Extremely acid Histosols, with a field‐pH value around 3, have been observed in coastal regions where pyrite (FeS2) containing peat bogs were drained. Alkaline peat (field‐pH around 7.8) has been reported from the Maldives. 15
  16. 16. 28/03/2011Use: Use: Sustainable use of peat lands is limited to extensive If carefully managed, Histosols can be very forms of forestry or grazing productive under capital‐intensive forms of arable In places, peat bogs are mined, e.g. for production cropping/horticulture, at the cost of sharply horticulture, of growth substrate for horticulture or to fuel increased mineralization losses. power stations. Deep peat formations and peat in northern regions are best left untouched. PROBLEM !!!  The exceptionally large total pore volume of Histosols (typically > 85%), their perishable nature and their normally poor chemical properties Grasses,  pose formidable problems to farmers and others concerned with ferns conserving use of Histosols. Reeds,  sedges Aquatic  plants Fibric Histosols are loosely packed in their natural state, with a bulk density (ρ) that is typically between 0.05 and 0.15 Mg/m3. Wide variation in chemical properties: Extremely acid Histosols, with a field‐pH value around 3, have been observed in coastal regions where pyrite (FeS2) containing peat bogs were drained. Alkaline peat (field‐ pH around 7.8) has been reported from the Maldives. 16
  17. 17. 28/03/2011 Grasses,  shrubs Mixed swamp  forest Grasses,  ferns Reeds,  sedges Aquatic  plantsGlobal distribution of Histosols 10. SPODOSOLS (‐od) 17
  18. 18. 28/03/2011 Typical feature is a bleached layer underlain by a dark organic rich layer. The Spodosols are probably the most photogenicsoils with several kinds of horizons, each with its owncolor, texture, and properties. Histosols in Sumatra 18
  19. 19. 28/03/2011Global distribution of Spodosols 11. ARIDISOLS (‐id) “Salt caps” The white layer in the subsoil is a calcic horizon or an accumulation of calcite. 19
  20. 20. 28/03/2011 Global distribution of Aridisols The Aridisols occur in the deserts and the soil doesnot moisten for more than a few weeks a year. Undersuch conditions, salts and other minerals accumulate inthe soil 12. GELISOLS (‐el) 20
  21. 21. 28/03/2011 The Gelisols occur in the tundra zone of northern latitudes or at very high elevations. The subsoil may be permanently frozen or frozen for long periods during the year. An ice layer forms the subsoil of this Gelisol from AlaskaGlobal distribution of Gelisols 21