This led to the drainage of Tøndermarsken, which is the only salt marsh in which pumping stations and levees have been built. Thanks to the levees, unlike most other streams, Vidåaen hardly ever overflows its banks. Ballummarsken and Ribemarsken have also been drained off, but only by means of canals.
The salt marsh on fire
However, the drainage of the salt marsh was not without problems. Former wetland plants in the salt marsh have been covered by the muddy water from the Wadden Sea and have transformed into a varied peat layer below the clay soil. If the peat layer is not kept moist, oxygen will enter the peat and cause it to ‘burn’ and subside. This has happened in the salt marsh of Ballummarsken, for instance, where some areas have subsided by up to 75 cm, resulting in the occurrence of large wet areas.
Cultivating the salt marsh
Until the mid-20th century, only a very small part of the salt marsh was cultivated. Instead, the flat grazing areas were used for bullock fattening and hay-making. Cultivation of the salt marsh developed in earnest from the 1950s to the 1970s. Oats was the dominant crop because it could be used as animal feed and was well-suited to moist soil. Furthermore, greater tractor power made it possible to plough the heavy salt marsh soil.