History of earth and soils
Geological processes and the climate have produced a diverse landscape with different kinds of soil. You can find the westernmost saline soils on the Eurasian continent, fertile black earth and sandy soils. This diversity of soil is the basis for diverse plant-communities occuring in this area.
How was the area of the Neusiedler See between the Alps and the Puszta formed?
About 16 million years ago, the area around today's City of Vienna, called the Wiener Becken, as well as the Small Hungarian Plain, were covered by sea. An inland lake was left as the open sea retreated to the east, about 13 million years ago.
The salt concentration decreased and enormous amounts of sediment were left. As this inland sea retreated even more to the east, the first plants started to grow in the Seewinkel.
About 13.000 years ago, at the end of the last Ice Age some tectonic shifts took place. During the process of this subsidence, the first bodies of water were formed in the area that is today called the Hanság (Waasen). After and during the late Ice Age, precipitations and other influx formed the first lake. Over the years this lake dried up several times and refilled with rain.
The history of the soils in Seewinkel makes clear, that the soils in this easternmost and lowest region in Austria are very different from those of river valleys or the foothills of the Alps. Austria's largest saline soil region is located in the Seewinkel, with a total area of 25km². Conditions for the formation of saline soils are optimal here: high annual average temperatures (10-11°C) and low annual precipitations (< 600 mm) accompanied by frequent windy conditions and long periods of sunshine, lead to heavy evaporation, causing the rise of saline water in the subsoil through capillary action.
There is only little sea salt and Glauber salt in the Seewinkel, but the sodium carbonate, the so called soda is very common. These salts are dissolved in the water of the salt pans.
Where the salt-containing stratum is not covered with gravel and sand-layers, so-called "Solontschak soil"(russian: sol = salt, kirghiz: tschaki = flowering) develops. In this sandy, light, unstratified soil salt migrates upwards with the rising water during periods of dryness, where it remains after evaporation of the water as a salt efflorescence. By means of this "upward leeching" the uppermost strata of the soil exhibits the highest salt concentration that prevents the creation of a humus layer.
Here at the saline lakes, only plants that are specialised on living under these extreme conditions can survive. Some plants have developed thick leaves in order to store the salt and absorb a lot of water to dilute the salt; others store the salt in the leaves and simply drop the leaves. Some can (like humans do with toxins) sweat the salt out by means of vesicular (salt) hair.
There is a second kind of soda soil, the 'Solonetz'. Here, the salt-containing layer is found some 35 to 70 cm beneath the surface. It is covered by an argillaceous low-salt layer upon which humus can form. During dry periods, the clay layer cracks open and forms polygonal columns. During humid periods, when the humidity penetrates the clay layer, it becomes impermeable. The vertical transport of salt can no longer take place, so there is no salt visible on the surface.
If layers of gravel and sand cover the salt-containing stratum, so called "chernozem" soils (black earth) evolve.
These soils are known for their thick humus layer and provide, unlike the saline soils, best farmland. The black earth soils that are not threatened by flooding are used intensively for agriculture.
Sand layers of different thickness can be found in the south of the Seewinkel. The most obvious deposit is the so called "bank" on the east shore of the Neusiedler See, that is - with some short interruptions- about 20 km long and ranges from Weiden/See to Sandeck in the very south of the National Park.
Water currents and debacles, or ice jams, coming from the northwest, the main wind direction, pushed the lake bottom and formed a bank up to 5 m high. This sandy soil stores humidity. Thanks to its perfect location between the lake and the saline lakes and its excellent supply of nutrients (lime) the world famous Seewinkel wines thrive here.