Plaggenesch

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Profile of a Plaggenesches: 40-50 cm overlay on fossil podzol

The plaggen soil (also Plagge soil or ash soil ) is an almost exclusively on the space Northwest Germany limited soil type , by an operation performed for centuries Plagge fertilization arose. Since the formation of this soil is based on human activity, it is classified in class Y (anthropogenic soils) in the German soil systematics . Its abbreviation is YE.

On the World Day of the ground in 2012 this type of soil from was Bundesverband floor and the German Soil Science Society as a bottom of the Year was proclaimed, 2013.

Origin and Distribution

Plagge ash was created through a special cultivation for soil improvement - the Plaggenwirtschaft. On nutrient-poor sandy soils, as are typical in the area of ​​the north-west German Geest , podzols , which are not good arable sites, usually form when there is medium to high rainfall . The arable farmers avoided these areas for as long as possible. When the population pressure rose sharply in the Middle Ages from around the year 1000, it became necessary to cultivate these low-quality areas, the yields of which were marginal and uncertain.

In order to guarantee the level and security of yield, and in view of the lack of mineral fertilizers , it was necessary to develop other forms of fertilization. In addition to the three-field economy that was customary at the time, the plague economy was developed in the north-west of Germany . A few corridors near the village or farm (called Esch in northern Germany ) were regularly fertilized with grass or heather pests. As sods will abgestochener, humus (grass) topsoil designated parts of the vegetation and scattered thereon. The plagues were collected in the so-called “common lands” (in the Osnabrück region, “Mark”), initially used as litter in the stables for about a year and then brought onto the fields together with the dung , ash and kitchen waste. In East Westphalia, the increase in the Plaggenesche often went hand in hand with the widening of the Sieke .

From archaeological excavations it is known that Plaggenesche emerged from the 11th century. In the Osnabrück region, one of the main areas in which Eschboden is distributed, it did not develop until the 12th and 13th centuries.

The end of the pest management came abruptly at the beginning of the 20th century, because with the introduction of mineral fertilizers at the end of the 19th century, the labor-intensive use of pests became superfluous. Since the 1930s at the latest, the blow has not been practiced any more. In the future, the soil type of the Plaggenesche will be preserved for a long time under arable use, is in a phase of degradation because it is no longer actively created. If there is no pest management, it will develop under the forest again in the long term towards Podzol.

Plaggene ash can only be found in very small areas around the world, because their distribution is linked to their former cultivation. More precisely, they are a regional peculiarity of northwest Germany with a focus on Osnabrück and Cloppenburg . Here they take up a large area of ​​up to 20 percent. But they occur in Central Europe up to the Ruhr area as well as in Belgium , the eastern Netherlands and Denmark . There are also analogous occurrences on the Orkneys and some Shetland Islands .

Medieval soil erosion

While the ash experienced a strong appreciation due to the plague economy, there was hardly any damage to the soil in its surroundings. Since the tapping areas were constantly disturbed and lay fallow for several years for the formation of a humus A-horizon, a large reserve of common land was required for an Esch. The area ratio was around 1: 5 to 1:30, depending on the location. After the plague was extracted, these soils were exposed to erosion without protection, so that large-scale swellings and water damage occurred. The loss of soil and nutrients set in motion a veritable devastation, which can still be proven today. There are numerous dunes from this medieval period of erosion throughout northwest Germany . In addition to erosion, overexploitation also led to extensive forfeiture .

properties

The constant supply of material caused an increase in the surface of the terrain and the creation of deeply humus Esch horizons, which have their own name in the German soil systematics (E-horizon). The soil horizon was raised at a rate of around one millimeter per year. A 40 cm thick E horizon must have been plagued for at least 400 years. Since the same areas were always plagued, there were abrupt changes in height over time (ash edges). These can be a meter.

The foreign mineral soil often led to a change in soil type . There are often siltier areas above the source material sand . The fertilizing effect of manure, ash and kitchen waste can be proven even decades after the end of the plague economy: The ash horizons still have a significant increase in the nutrients phosphorus (podzol sand: <20 mg P / 100 g soil; E horizon: 400-1000 mg P / 100 g soil) and potassium , where the phosphorus was supplied with the dung of the animals and the potassium with the ash. The increase in nitrogen content can no longer be determined because of the rapid leaching of this nutrient element.

With the plagues, so-called artifacts such as brick or ceramic fragments also got into the soil. The charcoal from the ashes strewn across the entire E-horizon is almost typical. Due to the high content of organic matter, not only the nutrient, but also the water balance of the soil has been improved.

As archive floors, Plaggenesche are of particular importance for archeology . They act like a protective layer that lies over cultural layers from prehistoric times. For example, the Stone Age artefact of Venus von Bierden was found under a layer of ash up to 60 cm thick, which offered protection from destruction by agriculture . The Eschboden in the Kalkriese find region had a similar effect as a possible location for the Varus Battle .

Leveling

The German soil systematics is the only one in the world that identifies Plaggenesche as its own soil type. In it they belong to class Y of terrestrial anthropogenic soils. In order to identify a soil as Plaggenesch, the combined thickness of the A and E horizon must be at least 40 cm. If this area is less thick, then it is the variety "with ash layer" of a different soil type.

The leveling reads: Ap / E / IIf ...

  • Ap: topsoil horizon (A) under arable use (p: plowed). Some of the Plaggenesche are not used for arable farming either. In this case there is an Ah horizon (humus (h) topsoil) on the surface. The A horizon is colored dark black by humus.
  • E: E is the actual ash horizon. It was created through many years of pest management and is consistently darkly colored by humus. If the pests came from sod, the color turns brown, as the organic material was easily decomposable and mineralization has progressed more strongly (brown ash). Plagues from heather, on the other hand, produced a gray color. The decomposition conditions in them are worse, so that humification predominated (Grauer Esch). Forest plagues can develop either color. The E horizon usually contains visible artifacts (charcoal, bricks ...). A strongly increased phosphorus content must be detected in the laboratory.
  • IIf ...: The original, buried ground lies below the E horizon (f: fossil). Since the soil material is often different, a shift change (II) may be due. The ... stand for the horizons of the covered ground, which vary depending on the location. In the case of the Podsol, which is often present, these are usually the horizons fAe, fBhs, Bv and C (see also Podsol ).

In the international soil classification World Reference Base for Soil Resources (WRB), the Plaggenesche mostly belong to the Plaggic Anthrosols .

use

To this day, Plaggenesche are classic arable sites. Due to the high sand content, these are well water-permeable, nutrient-poor locations. Sufficient, regular fertilization is a prerequisite for achieving satisfactory yields. However, the plague economy operated for centuries ensured a strong appreciation of the locations, which on average led to an estimated doubling of the land value figure and above all to safer yields. In the past, the classic cultivation crop was rye .

Due to the location of the Plaggenesche, this type of soil has often disappeared due to overbuilding. In many settlements, street names such as "Am Esch" or "Auf dem Esch" still refer to the former characteristics of these areas.

research

In the 1980s there was a geoscientific research project in northern Germany called "Esch Prospection". The Lower Saxony State Office for Soil Research from Hanover and the University of Kiel were involved. With the project, non-destructive archaeological prospecting methods , such as soil resistance measurements , were checked for thick ash layers.

In Lechtingen near Osnabrück, a “Plaggenesch information center” is being set up in the Lechtingen windmill , which is operated by the Osnabrück University of Applied Sciences .

literature

  • W. Amelung, H.-P. Blume , H. Fleige, R. Horn, E. Kandeler , I. Kögel-Knabner , R. Kretschmar, K. Stahr , B.-M. Wilke: Scheffer / Schachtschabel textbook of soil science. 17th edition. Heidelberg 2018, ISBN 978-3-662-55870-6 .
  • Wolf Eckelmann: Plagge ash from sand, silt and loam as well as surface changes as a result of the plague management in the landscapes of the Osnabrück district . Schweizerbart, Stuttgart 1980. ( Geological Yearbook , Series F, Soil Science 10, ISSN  0341-6445 , also: Göttingen, Univ., Diss., 1981)
  • J. Lienemann: Anthropogenic soils in Northwest Germany in their relationship to historical land use systems . In: Problems of coastal research in the southern North Sea area . 17, 1989, ISSN  0343-7965 , pp. 77-117.
  • G. Niemeier, W. Taschenmacher: Plaggenboden. Contributions to their genetics and typology . In: Westphalian research . 2, 1939, 1, ISSN  0083-9027 , pp. 29-64.
  • Ad Hoc Working Group Soil: Soil Science Mapping Guide . 5th edition. 2005, ISBN 3-510-95920-5 .
  • Jürgen Göttke-Krogmann: 1000 years of Plaggenesch culture in the Geest landscape of the Oldenburger Münsterland - a contribution to the revitalization of our soil awareness . In: Heimatbund für das Oldenburger Münsterland (Hrsg.): Yearbook for the Oldenburger Münsterland 2014. Vechta 2013, ISBN 978-3-941073-14-2 , pp. 227–243.
  • Bodo Zehm : The Plaggenesch - an archaeological archive floor becomes “Floor of the Year 2013” in: Archeology in Lower Saxony , pp. 154–159, 2013

Web links

Individual evidence

  1. ↑ Plaggenesch - 2013
  2. ↑ Britta Fecke in conversation with Frank Glante from the Federal Environment Agency : “We have to step up our activities”, dradio.de/dlf, Environment & Consumers , December 5, 2012.
  3. ↑ Plaggenesch location at the Lechtinger windmill