Reduktosol

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The reductosol (formerly also called methanosol) is similar to a gley , a soil with redoximorphic soil properties. While in gleyas an excess of water in the soil is responsible for this, in the case of the reductosol it is so-called reduct gases ( methane , carbon dioxide , hydrogen sulfide ) that displace the soil oxygen.

genesis

Since reduct gases are required to form a reductosol, this soil is found above all on gas pipes with leaks, in the vicinity of landfills (since processes take place in these areas, which can produce methane and carbon dioxide) or under the influence of post-volcanic mofats . Atmospheric oxygen is prevented from entering the soil by the formation of methane and carbon dioxide. Iron oxides and sulphates are reduced by these reductant gases and thus cause metal sulphides to turn black. Since microbial conversions have to take place anaerobically, blue-green Fe (II) / Fe (III) mixed oxides are formed. Furthermore, the soil is further acidified by the sulfuric acid that is formed . Reducing conditions can arise even if repeated contamination by liquids takes place as long as these contain easily degradable organic substances (e.g. sewage, slurry, fuels, etc.).

morphology

Next to or on landfills, soils have black colored subsoils due to metal sulphides, while ferrihydrite is responsible for a red-brown color in the topsoil (especially along root canals).

classification

A reductosol has so-called Y-horizons as a diagnostic horizon . A Yr horizon has gray or gray-green to blue-gray reduction colors, O 2 -free, CH 4 - and / or CO 2 -rich soil air as well as rH values ​​≤ 19 (the rH value is used as a measure of the redox conditions and is defined as the negative decadic logarithm of the hydrogen partial pressure). The yo horizon is usually on top of this horizon . This is a red-brown colored (especially along root tubes and on aggregate surfaces) Y-horizon due to Fe oxides, with at least partially increased methane and / or carbon dioxide contents of the soil air. Here, rH values ​​of ≤ 19 are given.

In addition, a Yg horizon is also proposed, which is characterized by rust stains (especially in the interior of the unit) and partly bleached unit surfaces as well as partly low redox potential (analogous to the Yo horizon).

In the international soil classification World Reference Base for Soil Resources (WRB), the reductosols mostly belong to the Reductic Gleysols .

ecology

Due to the lack of oxygen in the subsoil, deep roots are damaged and die, while shallow roots can grow normally. In addition, a high Mn content can also damage plant growth. In addition, toxic Al concentrations in the soil solution are to be expected in dystrophic reductosols . On the other hand, due to the activity of microorganisms and the resulting heat in the soil, the vegetation period can be extended.

literature

  • H.-P. Blume: Reductosols - a new class of the German soil systematics. In: Communications of the German Soil Science Society. Volume 85, Issue No. 3, 1997, pp. 1103-1106.
  • H.-P. Blume, P. Felix-Henningsen: Reduktosols. In: K. Stahr, H.-P. Blume, P. Felix-Henningsen, H.-G. Frede, G. Guggenberger, R. Horn (Ed.): Handbook of soil science . Loose-leaf collection. 28. Result delivery, chap. 3.3.2.11, Weinheim (1996 -) 2009, pp. 1-24.

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