Every year a panel of experts chooses the floor of the year. For 2025, this title has now been won by the so-called Rendzina – a soil type that is formed on lime, dolomite or gypsum rocks. Rendzines are often dry, but ecologically valuable. They provide habitat for rare flowering plants and numerous soil organisms. Rendzines occur in Germany, among other places, on the chalk cliffs of Rügen.
No matter how inconspicuous they may seem, soils do us humans and life on earth a great service. They are a habitat for large and small creatures, store carbon, filter pollutants and protect against erosion and flooding. In order to recognize the diverse achievements of different soil types, specialist soil science associations have chosen the Soil of the Year every year since 2005.
A “communicating” soil type
For 2025, the jury chose the so-called Rendzina – a soil type that is formed on lime, dolomite or gypsum rock and is characterized above all by the fact that the rock subsoil lies directly beneath the dark, humus-rich topsoil. The name Rendzina comes from Polish and means something like “to communicate”. Since rendzines contain a lot of gravel and stones, there is a characteristic scratching and squeaking sound when plowing. The soil then “communicates” with its plowman, so to speak. But Rendzines are actually less suitable for agriculture, as the soil can only be worked superficially due to its lack of depth and large pieces of rock always come to the surface during plowing.
Since water usually seeps away quickly through the fissured and soluble rock, a dry grassland with numerous rare flowering plants often forms on the Rendzina. But it also happens that entire forests grow on this type of soil, often in the form of stately old beech stands. Animal residents such as earthworms, insects and microorganisms also find a home in the slightly alkaline, crumbly topsoil of the Rendzinen. Due to the favorable living conditions, the soil organisms quickly convert plant litter into organic soil matter and thus improve the soil structure. This in turn promotes air exchange and the storage of nutrients.
Also common on the chalk cliffs of Rügen
Rendzines were formed primarily in karst areas, low mountain ranges and the Alps from rocks of different geological ages. In Germany, for example, they occur on the Jurassic limestone areas of the Franconian and Swabian Alb and in the Muschelkalk areas of Thuringia. There are also Rendzinen in the far north: on the limestone from the Cretaceous period – including the famous chalk cliffs of Rügen. The Rügen chalk is used, for example, for cement production, the production of fertilizer lime and in products from the electrical, cosmetics and pharmaceutical industries. Once the mining of raw materials has ended, the mining areas are prepared again so that yields can be created again over the course of decades.
Source: GeoUnion Alfred Wegener Foundation