Rendzina

As rendzina or rendsina a shallower soil is referred to in the Soil Science and Geology, which forms on carbonate - or gypsum- rich rocks. The soil type has two horizons, and is in the class R (Ah / C soil) divided. Its abbreviation is RR.

Rendzina floors are typical of karst and many mountains, but can in favorable conditions to black or brown earth evolve.

Origin of the name

The term rendzina comes from the Polish language ( Rędzina ) and is modeled after the shuffling sound made by a plow when hitting hard rock.

Emergence and dissemination

Can Rendzinen form on carbonate - or gypsum- rich solid rock or loose material (≥ 75 % by weight carbonate or gypsum). They are thus a development of Intitialböden Syrosem or Lockersyrosem. By far the most common starting material with this property is the limestone. More solid starting rocks are marble, the magnesium-containing dolomite and gypsum (calcium sulfate). As carbonatreiche unconsolidated rocks are Cretaceous (eg on Rügen) or geologically very young Seekreiden (eg in the Bodensee area ) before. In addition, may be considered nowadays calcareous technogenic materials such as concrete or brick.

In addition to the physical weathering, which loosens the structure of the solid rock, also acts as the solution weathering in the genesis of Rendzinen. Carbonates are solved by kohlenstoffdioxidhaltiges water and transported to the leachate as bicarbonate. The formula is considered coarse:

CaCO3 H2O CO2 → 2 HCO3- Ca2

When sulfates a simple solution expires, which also removes the sulfate with the leachate.

The purer or fissured, the material, the faster the solution weathering expires. In the upper floor, the insoluble matter, especially clay minerals accumulate. This form of soil formation runs compared to the weathering of carbonate - or gypsum-free soil relatively quickly. In addition, it is in the upper bottom in the accumulation of humus due to the biological activity. The Ah horizon of a rendzina is significantly humos but still carbonate or gypsum content, even if the levels are significantly lower than in the parent rock.

The rendzina goes into more differentiated soils with increasing carbonate or gypsum depletion. If the A horizon 40 cm or more, the class of chernozems is achieved. If, in the ground to form a verbraunten horizon, a brown soil developed (B- horizon in the subsoil ) or Terra fusca (T- horizon in the subsoil ). The rendzina is therefore usually a stage of development of a site, which is crossed relatively quickly. However, the erosion can obtain the soil type of the rendzina permanently, because of the continuous erosion throws back the soil development resistant.

The classic distribution area of ​​Rendzinen located in karst areas and mountains, where calcareous material and slope meet. In the cuesta landscapes of the highlands they arise everywhere where exposed limestone layers.

Leveling

The rendzina has as a non- deep soil horizons two: Ah / cC.

• Ah - is above the starting material is a humic ( h) surface horizon (A). Its thickness must be> 2 cm and ≤ 40 cm. The coloration is due to the organic material usually dark gray to blackish. In field use, this horizon is designated Ap ( p plow horizon).
• CC - Under the Ah horizon is directly the starting material ( C). This must be carbonatisch or gypsum content ( c ), that have a lime or gypsum content of ≥ 75 % by mass. Often the prefix c is omitted since it is mandatory for the speech as rendzina. In part, the C horizon is weathered and is referred to as Cv (v for the weathered ).

In the international soil classification WRB Rendzinen belong to the Leptosolen, Chernozemen or Kastanozemen.

Properties

The Ah horizon is still carbonate or gypsum content in the rule. Thus, the pH is usually in the basic range 7 to 8 Since the residue of the solution weathering consists mainly of clay, the soil type of Rendzinen is fine with up to 60 % by mass of clay. In the clay are in principle also many nutrients, so that the cation exchange capacity high values ​​of up to 40 cmol reached. Another special feature is the very high pore volume can be considered. While it is in average soils at 45 % by volume, up to 70 vol % are possible in Rendzinen. This ensures excellent ventilation, workability and drainage of the sites.

Due to the high pH, nutrients and pore soils provide ideal conditions for soil organisms. Registered organic material is rapidly degraded and fully incorporated into the soil. The humus is in the form of Mull and has the highest possible quality. The entire A horizon is very rich in humus (often 10-20 % by mass) and has an excellent, loose crumb structure.

Use

Despite the good basic conditions above Rendzinen are only suitable due to their Flachgründigkeit for agricultural use. On the one hand the mechanical cultivation is hindered. On the other hand, lack a sufficient soil volume for water storage or supply of nutrients, so that the sites are rather sparse. The informal storage with high pore volume, the soils tend principle for fast drying. In particular, on south-facing slopes and in low-rainfall winters they are very threatened by drought. For the plants of small powerful Ah horizon is hardly the root zone. Last but not least are Rendzinen mostly on slopes with more or less strong tendency. When a land use is therefore often occurs on soil erosion.

At the time of Pferdepflüge the plowing depth was approximately 15-20 cm. This depth is often permitted the agricultural use of Rendzinen without the stony ground to touch. The regular contact of plow and limestones caused buzzing noise, which led to the naming of the soil type. The introduction of large agricultural machinery plow depth was reduced to about 30 cm, so that the Flachgründigkeit often led to problems. As long as the erosion and the water supply in the grip of providing high yields can be achieved on Rendzinen. Because of the numerous problems Rendzinen but are now rarely used as arable.

In some cases, especially in karst areas, pastures can be found on which occurs from a conservation point of view valuable limestone grassland with extensive use. Mähweiden are rare, since protruding stones can endanger the cutter bar.

A typical in Central Europe use is forestry. Rendzinen are classic sites for beech forests.

Other Ah / C soils

In addition to the rendzina include three other soil types in the class of Ah / C soils that differ diagnostically in the lime content of the starting material:

• The Pararendzina built on marly material ( carbonate content > 2 wt % and < 75 % by mass). Most are unconsolidated rocks.
• The Ranker forms on lime- or - free hard rock ( carbonate content ≤ 2 % by mass).
• The regosol is on low lime loose material ( carbonate content ≤ 2 % by mass).