Eutrophication: The role of agricultural ditches in eutrophication of the Baltic Sea

Author: BalticSea2020
Year published: 2011


We do not know enough about the role of agricultural ditches in eutrophication of the Baltic Sea. This is shown by a collation of knowledge* from the Swedish University of Agricultural Sciences and BalticSea2020.

The collation also shows that there is often a lack of knowledge on how effective different measures are in reducing phosphorus leaching from agricultural ditches. According to the researchers, an experimental facility should therefore be established where different measures can be tested and evaluated under controlled conditions.

"It is important to increase knowledge of how effective measures are under different conditions as quickly as possible and consequently make it possible for the most appropriate measures to be taken," says Conrad Stralka, Executive Director of BalticSea2020.

There are a total of 90 000 km of agricultural ditches in Sweden. The ditches were originally dug to increase the acreage of productive land and are needed for good crop production. At the same, rainwater and groundwater carry nutrients via the ditches to watercourses, lakes and seas. Measures that reduce phosphorus losses from ditches to watercourses can have favourable effects on environmental problems related to eutrophication, but the level of knowledge on which measures are actually effective is low. Buffer zones and small sedimentation ponds are two examples of this.

"Many measures are required in a large proportion of existing ditches and drainage systems to reduce phosphorus transport to the Baltic Sea. The measures therefore must not be too difficult or expensive," says Joakim Ahlgren, a researcher at the Swedish University of Agricultural Sciences (SLU).

The role, functionality and effectiveness of the ditches have not yet been studied systematically. An experimental facility would also make it possible to find the most cost-effective measures for different conditions.

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* Measures to improve phosphorus retention in open ditches in areas at risk in the agricultural landscape around the Baltic Sea, by Joakim Ahlgren, Faruk Djodjic & Stefan Löfgren at the Department of Aquatic Sciences and Assessment, SLU. The whole collation of knowledge can be downloaded from www.balticsea2020.org.

The BalticSea2020 foundation has financed the work.

About BalticSea2020

BalticSea2020 is a private foundation whose objective is to contribute to reversing the trend in the Baltic Sea by 2020. This is to be achieved by spending a donation of SEK 500 million on practical measures in research, opinion-forming and active involvement in projects.

About SLU

The vision of SLU is to be a world-class university in the life and environmental sciences. SLU contributes knowledge on the eutrophication of our aquatic systems, for instance through:

Our focus areas

fisheryThe stock of predatory fish is crucial for the state of the Baltic Sea. Therefore, the Foundation worked to ensure that the environmental effects of fishing should be a central part of the EU's Common Fisheries Policy. The Foundation also worked on projects to increase the proportion of predatory fish, such as cod, pike and perch. Read more

eutroEutrophication is caused by emissions of nutrients that come from e.g. agriculture, water treatment plants, sewage and transportation. To find measures that could reduce emissions the Foundation worked on projects in agriculture, industrial animal farms and the coastal zone, to research on measures to catch or bind nutrients. Read more

seagull-informationTo create awareness about the threats and opportunities the Baltic Sea is facing, the Foundation initiated a 10-year media and film project with journalist Folke Rydén and photographer Mattias Klum. The Foundation has also supported Stockholm University Baltic Sea Centre (Baltic Eye), and Baltic Sea Science Center at Skansen. Read more