Clay-humus complex

In soil science, clay-humus complex refers to the aggregate formation of organic fragments such as humic substances with inorganic particles such as clay minerals through hydrogen bonds or the inclusion of metallic cations . Both clay minerals and humic substances are soil colloids .

education

Humic substances are able to combine individual soil particles to form a crumb structure and thus stabilize the soil structure . Such aggregate structures are formed from clay colloids through the connection of calcium bridges with humic substances in humus topsoils. While the clay minerals and the humic acid residues (organic dipoles) of the humus particles are negatively charged, the Ca ²⁺ ion or other multivalent cations, for example Mg ²⁺ , form a neutralizing bridge. The resulting organo-mineral compounds are called clay-humus complex or lime-clay-humus complex .

A particularly intensive mixture of organic and mineral substances takes place in the intestine of the earthworm, where the aggregates are stabilized by mucilage. The THK that are formed are further built up into crumbs by bacteria and fungi. This living construction only takes place when the soil life is very active in humus and nutrient-rich topsoils, in which an optimal crumb structure and the humus form " gauze " can form.

meaning

The complex formed stabilizes the soil against erosion and silting up, creates favorable conditions for the air and water balance in the pore volume of the soil and thus causes a higher soil fertility . Due to the binding of the positively charged nutrient salt ions, these substances, which are important for the plant, cannot be washed out into deeper soil layers by rain. They are later released by the plant through an ion exchange from the THKs and used.

The elasticity of the crumb structure formed is favorable. The soil fermentation is promoted more sustainably by the soil life with the formation of clay-humus complexes than is possible, for example, with a frozen fermentation . The physically determined structures of the segregate structure are only beneficial for plant cultivation for a short time because they quickly lose their function through cracking and further decay.

Excessive tillage, however, leads to the disintegration of every crumb structure - in horticulture this cultural error is referred to as "milling to death" of a soil.

See also

• Chemical soil properties
• humus
• Liming
• Turbation

literature

• D. Schroeder: Soil Science in Key Words , Unterägeri 1984, p. 62, ISBN 3-266-00192-3

Individual evidence

1. ^ Gisi Ulrich, Schenker Rudolf, Schulin Rainer, Stadelmann Franz X., Sticher Hans: Bodenökologie . 2nd Edition. Thieme, Stuttgart 1997, ISBN 3-13-747202-4 .
2. ↑ Kuntze, Roeschmann, Schwerdtfeger - Soil Science (Eugen Ulmer 5th edition 1994)
3. ↑ Scheffer, F .; Schachtschabel, P .: Textbook of Soil Science . 13th edition. Ferdinand Enke Verlag, Stuttgart 1992, ISBN 3-432-84773-4 .
4. ↑ Heistinger, A .; Grand, A .: Make organic fertilizers yourself. Earthworm humus - green manure - compost . 1st edition. Löwenzahn, Innsbruck 2014, ISBN 978-3-7066-2519-7 .