Gypsisol

Gypsisol

The Gypsisol (Greek Gypsos or Latin gypsum = gypsum) is a ground class of the World Reference Base (WRB) and the Food and Agriculture Organization of the United Nations (FAO). Gypsisols are widespread in deserts and semi-arid arid areas with irregular rainfall (<200 mm per year). Characteristic of the soil type is the low humus mineral soil with secondary calcium sulphate enrichment, which partly leads to hardening or cementation in the subsoil in the upper 125 cm of the soil (or 100 cm according to WRB). The A horizon above is mostly shallow. The browned or de-activated B horizon, which is located below the A horizon, often shows calcium deposits in addition to plaster crusts and soft plaster efflorescence . Gypsisols have no clear equivalent in the German soil system of 1990.

description

The gypsisols are floors made of gypsum or anhydrite . Like calcisols , gypsisols are soils that are enriched with gypsum or lime . However, lime is much more common than gypsum. Both soils are often in transition forms to one another. Depending on the gypsum content, gypsisols are brown, light brown or white, with a higher gypsum content causing a lighter color. While the pH value is between 7 and 8 and is therefore neutral or slightly basic, the base saturation is 100%. The availability of phosphorus is low because the pH is too high .

The base class is different from Calcisolen, Solontschaken , Solo networks and Durisolen by their amounts of salts , sulfates , carbonates and silica . Certain chemical compounds from minerals are enriched in these soils in the top 125 cm. The background to this is the high level of evaporation, the low level of water seepage and the low air and water supply, which prevent chemical reactions in deeper soil areas. Also up to this depth there is a real hardening horizon with gypsisol.

Gypsisols have either a petrogypsic or a gypsic horizon that is at least 10 cm thick and cannot be penetrated by roots . The enrichment horizon must be over 15 cm in size and have a sulfate content that is over 5% higher than the original substrate. In contrast to the gypsic horizon, the petrogypsic horizon is hardened or cemented . Root penetration is only possible if there are cracks. At least 5% of the horizon is plaster of paris. With the gypsic horizon, lime can appear on the aggregate surface through efflorescence, while with an existing petrogypsic horizon, the lime appears through hard banks . In the mixed form with calcisol, lime accumulations can be found above the gypsum accumulations during the formation of surface water . The reverse is true for groundwater formation. In the underbody , soluble can easily salts accumulate. The topsoil horizons have only a low electrical conductivity . The formation of attapulgite , special clay minerals , is induced by gypsum precipitation .

Gypsisols are low -humus , often salty soils that show neutral reactions. The gypsum accumulations of the gypsisole lead either to the hardened petrogypsic or the soft gypsic horizon. If the petrogypsic horizon is at a shallow depth, gypsisols have only a small water storage capacity . Not infrequently in Gypsisolen petrocalcic or - calcic -Horizonte or reliktisch usually duric- or petroduric to be found -Horizonte. The horizon sequences are usually as follows:

• A (y) -Cy,
• A-By-C (y),
• A-Bym-C or less often
• A- (E-) Bty-C (y).

Due to the high gypsum content, coherent, structurally poor structures are found in gypsisols. As a result, gypsisols have a low infiltration rate . Likewise, only a small amount of organic matter can be found in gypsisols. The organic carbon content is less than 0.6%. The potential cation exchange capacity can reach up to 10 to 20 cmol (+) kg ⁻¹ FE.

While soils with a relatively low gypsum content are called hypogypsic-gypsic horizons, gypsic horizons are called hypergypsic. They are located on higher, i.e. older, terraces and usually have a high gypsum content. There are also petrogypsic horizons, which are often found on the top and oldest terrace steps and knolls.

The Hypogypsic Qualifier is characterized by a plaster of paris content of a maximum of 25% gypsum mass. This occurs as pseudomycelia , in coarse single crystals and crystal nests as well as in fine crystals in small solum veins . Accordingly, hypogypsic qualifications are common in soils with young parent rock, where the gypsum formation process is still ongoing. Hypergypsic, on the other hand, is used to mark floors where the gypsum content makes up at least 50% of the mass. This occurs in the form of massive gypsum efflorescence. In contrast to the hypogypsic qualifier, gypsum formation processes are common for the hypergypsic qualifier that have been going on for a long time. Accordingly, hypergypsic floors are often found.

Bottoming out

Gypsisols can arise from the following processes:

1. Pseudomycelia arise from meandering fine threads that are located in the pore spaces of the solum and often follow the root canals. This leads to the recent plaster training.
2. Massive gypsum efflorescence occurs together with gypsum crystal nests and pseudomycelia in soils with a sandy texture and a gypsum content of at least 50%.
3. Gypsum crystal accumulations can develop through various processes. They often go from needle-shaped single crystals produced, but also from crystal accumulations in valleys with temporarily high standing, saline water. Another possibility emergence form deposits on terraces crushed stone and fibrous crystals which are in coarse growing media. Furthermore, gypsum crystal accumulations can arise through crystal nests in pore spaces that are above, below, but also in a calcic horizon.
4. Petrogypsic horizons are created by cemented or hardened white crusts from massive, compact microstructures made of pure gypsum. They have an average crystal size of 0.01 to 0.05 mm. The deeper the horizon, the coarser it is.
5. Polygonal gypsum crusts are a transitional form of massive gypsum efflorescence and the petrogypsic horizon. The plates are 2 to 5 cm thick.

Occurrence

Distribution of Gypsisol floors

Gypsisol is a type of soil that occurs in arid areas. It mostly arises from loose rock of colluvial , alluvial or aeolian origin. Gypsisols are often found in the depressions of dried-up lakes, but also on river terraces that have a high groundwater level, as well as on exposed prehistoric layers of gypsum. The distribution areas are therefore small and in special locations.

Like calcisol, gypsisol can also be found not only in full, but also in semi-deserts . Gypsisol can therefore be found in arid climatic areas . Gypsisols can also occur in semi-arid areas. They occur in nemoral areas and in dwarf shrub semi-deserts.

Gypsisols are most widespread in north and south-west Africa as well as in Somalia and the Arabian Peninsula . Gypsisols are also found in Anatolia , Syria , Iraq , Iran and Central Asia . Gypsisols can also be found in a few places in Australia and the southwestern United States . In total, Gypsisols take up around 100 × 10 ⁶  ha globally .

Gypsisols, together with calcisols and Solontschaken, determine the soil landscape in the dry lee of the Andes . In addition, Gypsisols occur together with Calcisols and Solontschaks in the intramontaneous basin layers of the Tian Shan and in the Central Asian deserts of Kyzylkum , Karakum , Taklamakan , Dzungarei and Gobi .

Gypsisols can also be found in salt deserts . So dune valleys of the Erg landscape type often have loamy soils that can be gypsum Solontschake. In the Hamadas landscape type, clay and silt-rich end pans can often be found in full deserts . These sebkhas are enriched with gypsisol or solontschak. Furthermore, extensive sebkhas can be found in the former lakes of the Serir landscapes, some of which contain gypsisols or Solontschake extremely gypsum or salty.

Gypsum is widespread and important as a newly formed mineral in the Atacama and Namib coastal deserts . In the west of the Namib, voluminous plaster crusts have developed. These are partially divided into two mineral profiles : Above is mainly gypsum, below an old crust of lime .

The gypsum was created through high biomass production through nutrient-rich, cold upwelling waters, as hydrogen sulfide is formed during the anaerobic decomposition of the dead marine macrofauna as well as the phyto- and zooplankton . The gas then enters the air and is converted into sulfate as a result of photochemical processes . On the mainland, the hydrogen sulfide reacts on contact with blown lime dust to form calcium sulfate , i.e. gypsum, which is easily soluble. The gypsum gets into the ground through moisture, for example through fog or rain.

The lime was created through a sinking infiltration process under more humid climatic conditions. The plaster of paris formed in parallel was rinsed out of these areas. With the beginning of the full or extreme desert climate, gypsum was formed over the limestone. Sometimes the lime disappeared completely. Due to the thickness of various gypsum crusts, a full desert climate has been concluded here for at least 100,000 years, as there was little tendency to erosion during that time .

use

Due to the aridity of the regions in which gypsisol occurs, only moderate biological activity takes place in the gypsisol soils . With an average annual precipitation of 400 mm and a gypsum content of the topsoil of a maximum of 25%, both pasture use and rain- fed cultivation are possible on gypsisols . Large parts of Gypsisol areas are used for extensive grazing. The cultivation of goods is mainly possible on the soil that has only a small amount of gypsum in the top 30 cm.

The cultivation on gypsisol soils is agriculturally worthwhile, especially when the gypsum deposits are still young and there is a large amount of water. With correct irrigation, a good yield can be obtained even on soils that contain more than 25% gypsum. Even with a high gypsum content in the soil, high yields on gypsisols are possible through irrigation. Typically, on Gypsisol floors apricots , cotton , dates , barley , corn , wheat , grapes , and forage grasses grown. In order to be able to achieve a satisfactory yield, irrigation and mineral fertilization, especially with sodium , phosphorus , potassium and magnesium, are necessary despite the risk of erosion . Otherwise it is possible that there will be no income.

With a higher gypsum content, the absorption of potassium and magnesium is made more difficult for the plants due to potassium / calcium or magnesium / calcium antagonisms. Petrogypsic horizons and hard gypsum or lime bank layers have a negative effect on the yield due to the resulting root barriers and can also completely prevent it.

Nevertheless, because of the low vegetation cover such as xerophytic woody plants and annual grasses, gypsisol soils are mostly used as extensive pasture. Another hindrance is that Gypsisol soils are prone to erosion and desertification . With soil irrigation there is a risk of soil salinization and the dissolution of the gypsic or petrogypsic horizon. However, irrigated agriculture on gypsisol soils can lead to the dissolution of the gypsum. This can cause the soil to erode and sink, collapse and corrode the soil structures . This can lead to subsidence.

literature

• Wulf Amelung, Hans-Peter Blume , Heiner Feige, Rainer Horn, Ellen Kandeler , Ingrid Kögel-Knabner , Ruben Kretzschmar, Karl Stahr , Benrdt-Michael Wilke: Scheffenhofer / Schachtschabel textbook of soil science . 17th edition. Springer Spectrum, Heidelberg 2018, ISBN 978-3-662-55870-6 .
• Wolf Dieter Blümel : Deserts . Eugen Ulmer, UTB, Stuttgart 2013, ISBN 978-3-8252-3882-7 .
• Food and Agriculture Organization of the United Nations (Ed.): World reference base for soil resources 2014. International soil classification system for naming soils and creating legends for soil maps. Update 2015 . Rome 2015, ISBN 978-92-5108369-7 ( PDF ).
• Wolfgang Zech , Peter Schad, Gerd Hintermaier-Erhard: Soils of the world. A picture atlas . 2nd Edition. Springer Spectrum, Heidelberg 2014, ISBN 978-3-642-36574-4 .

Individual evidence

1. ↑ ^{a b c d e f g h i j k l m n o p q r s} Wolfgang Zech, Peter Schad, Gerd Hintermaier-Erhard: Soils of the world. A picture atlas . 2nd Edition. Springer Spectrum, Heidelberg 2014, ISBN 978-3-642-36574-4 , p. 74 .
2. ↑ ^{a b} Gypsisols. In: Spektrum.de. Retrieved March 10, 2019 . 
3. ↑ ^{a b c d e f g} Wolf Dieter Blümel: Deserts . Eugen Ulmer, UTB, Stuttgart 2013, ISBN 978-3-8252-3882-7 , pp. 131 .
4. ↑ ^{a b c d e f} Wulf Amelung, Hans-Peter Blume, Heiner Feige, Rainer Horn, Ellen Kandeler, Ingrid Kögel-Knabner, Ruben Kretzschmar, Karl Stahr, Benrdt-Michael Wilke: Scheffenhofer / Schachtschabel textbook of soil science . 17th edition. Springer Spectrum, Heidelberg 2018, ISBN 978-3-662-55870-6 , p. 454 .
5. ↑ Wolf Dieter Blümel: Deserts . Eugen Ulmer, UTB, Stuttgart 2013, ISBN 978-3-8252-3882-7 , pp. 130 .
6. ↑ Wolf Dieter Blümel: Deserts . Eugen Ulmer, UTB, Stuttgart 2013, ISBN 978-3-8252-3882-7 , pp. 131 f .
7. ^ ^{A b c} Wolfgang Zech, Peter Schad, Gerd Hintermaier-Erhard: Soils of the world. A picture atlas . 2nd Edition. Springer Spectrum, Heidelberg 2014, ISBN 978-3-642-36574-4 , p. 75 .
8. ^ ^{A b} Wolfgang Zech, Peter Schad, Gerd Hintermaier-Erhard: Soils of the world. A picture atlas . 2nd Edition. Springer Spectrum, Heidelberg 2014, ISBN 978-3-642-36574-4 , p. 69 .
9. ^ ^{A b} Wolfgang Zech, Peter Schad, Gerd Hintermaier-Erhard: Soils of the world. A picture atlas . 2nd Edition. Springer Spectrum, Heidelberg 2014, ISBN 978-3-642-36574-4 , p. 39 .
10. ^ Wulf Amelung, Hans-Peter Blume, Heiner Feige, Rainer Horn, Ellen Kandeler, Ingrid Kögel-Knabner, Ruben Kretzschmar, Karl Stahr, Benrdt-Michael Wilke: Scheffenhofer / Schachtschabel textbook of soil science . 17th edition. Springer Spectrum, Heidelberg 2018, ISBN 978-3-662-55870-6 , p. 484 .
11. ↑ Wolf Dieter Blümel: Deserts . Eugen Ulmer, UTB, Stuttgart 2013, ISBN 978-3-8252-3882-7 , pp. 131 f .
12. ↑ Wolf Dieter Blümel: Deserts . Eugen Ulmer, UTB, Stuttgart 2013, ISBN 978-3-8252-3882-7 , pp. 132 .
13. ↑ ^{a b c} Wulf Amelung, Hans-Peter Blume, Heiner Feige, Rainer Horn, Ellen Kandeler, Ingrid Kögel-Knabner, Ruben Kretzschmar, Karl Stahr, Benrdt-Michael Wilke: Scheffenhofer / Schachtschabel textbook of soil science . 17th edition. Springer Spectrum, Heidelberg 2018, ISBN 978-3-662-55870-6 , p. 456 .
14. ↑ ^{a b} * Food and Agriculture Organization of the United Nations (ed.): World reference base for soil resources 2014. International soil classification system for naming soils and creating legends for soil maps. Update 2015 . Rome 2015, ISBN 978-92-5108369-7 , pp. 160 .
15. ↑ Food and Agriculture Organization of the United Nations (Ed.): World reference base for soil resources 2014. International soil classification system for naming soils and creating legends for soil maps. Update 2015 . Rome 2015, ISBN 978-92-5108369-7 , pp. 160 .
16. ↑ Food and Agriculture Organization of the United Nations (Ed.): World reference base for soil resources 2014. International soil classification system for naming soils and creating legends for soil maps. Update 2015 . Rome 2015, ISBN 978-92-5108369-7 , pp. 160 f .