Gypsum on fields protects the Baltic Sea from eutrophication

Phosphorus runoff from fields causes eutrophication in the Baltic Sea and enables blue-green algae to thrive. Nutrients are prevented from entering the Vantaa River by spreading gypsum on fields. The Vantaa River gypsum treatment project is one of the initiatives of the John Nurminen Foundation. Orion supports the foundation’s work.

There they are: two piles of white gypsum, ready to spread on fields after the harvest season. On a partly cloudy Friday morning, the gypsum piles have attracted a large number of people: researchers, journalists, members of associations and people in charge of the gypsum treatment project. Kallepekka Toivonen, the head of the Myllymäki Farm in Nurmijärvi, is also present, of course.

The farmer decided to join the gypsum treatment project with an open mind, well aware of the eutrophication effect of his business on the Baltic Sea. When it was suggested that phosphorus and gypsum be spread on Toivonen’s fields to bind solid matter in the soil, he said “yes, please”.

“Some agricultural nutrients inevitably end up in natural waterways, but spreading gypsum on fields is a quick and effective way to prevent runoff. This benefits not only the Baltic Sea, but also the Vantaa River, which is dear to me,” says Toivonen.

Phosphorus onto the field, not into the sea

The environmental benefits of gypsum are indisputable.

“When gypsum is spread on fields, it dissolves in the soil and facilitates the formation of larger particles of soil. These soil particles bind up phosphorus effectively. Gypsum also improves the structure of the soil and prevents erosion in cultivated areas, in that it binds phosphorus for a longer period of time to be reused by plants,” says Maija Salmiovirta, Project Manager at the John Nurminen Foundation.

Phosphorus that stays in the field will not burden the Baltic Sea. In a field treated with gypsum, the field holds half of the amount of phosphorus and soil that would usually end up in the sea.

“One gypsum treatment is enough to bind that amount of phosphorus and solid matter in the field for five years. In other words, the farmer won’t need to go through the trouble of spreading gypsum after each harvest season,” Salmiovirta adds.

Gypsum on fields prevents blue-green algae in the sea

The Vantaa River gypsum treatment project has reduced the annual phosphorus loading in the Gulf of Finland by two tonnes. Although the amount sounds impressive, Salmiovirta points out that the long-term effect of five years should also be kept in mind.

“Considering the long-term effect, the amount of nutrients not ending up in the sea in the Uusimaa region is around ten tonnes.”

But the facts get even more impressive: a kilo of blue-green algae needs only two grams of phosphorus to grow! This means that gypsum prevents a huge amount of these poison green algae from growing in the first place.

“Take out your calculators,” Salmiovirta says.

Gypsum does not interfere with growth

At the moment, Kallepekka Toivonen is one of the very few farmers in Finland whose fields are treated with gypsum. The total area of fields suitable for gypsum treatment in Finland is around 540,000 hectares. Of this total, about 5,000 hectares have been treated.

“The potential for gypsum treatment around the Gulf of Finland and the Archipelago Sea is enormous. Fields in lake regions are not suitable for this purpose, as gypsum treatment slightly increases the sulphate content of runoff. Unlike in the Baltic Sea, lakes are harmed by this.”

According to Salmiovirta, politicians now need to ensure funding for extensive gypsum treatment. In addition, favourable attitudes are needed from field owners. The future will show whether gypsum treatment will take off.

“I hope farmers will join the project with an open mind. Gypsum has not been found to have any harmful effects in agriculture. It does not interfere with growth, nor does it affect the taste of plants or change the pH of the field.”

Private funding for the gypsum treatment project

The John Nurminen Foundation launched a fundraising campaign for the Vantaa River gypsum treatment project in 2018.

“Two-thirds of the total project budget of EUR 1.2 million was covered through donations from companies and private individuals, and the Ministry of the Environment provided the remaining third. Orion has supported the Clean Baltic Sea projects of the John Nurminen Foundation since 2018,” says Salmiovirta.

Orion and the John Nurminen Foundation have signed an agreement on the foundation’s main partnership for 2018–2020. Protecting the Baltic Sea is one of the main themes of Orion’s corporate responsibility and is aligned with its own approach.

In 2019, the gypsum is provided free of charge for the project by Yara, a factory in Kuopio. The expenses mainly arise from the transportation of the gypsum and the fees paid for spreading it. Farmers joining the project receive a financial incentive from the foundation.

Salmiovirta is grateful to each donor for their input for the benefit of the Baltic Sea. She believes that Finns increasingly want to take environmental action.

“It’s not too late to join the project. Next, we will start gypsum treatments in fields in the Archipelago Sea region, and our work will also continue after that.”


Text and photo: Essi Kähkönen

The Vantaa River gypsum treatment project is funded by private supporters of the John Nurminen Foundation and by the Ministry of the Environment. The project is being implemented by the John Nurminen Foundation, the Vantaa River and Helsinki Region Water Protection Association, the University of Helsinki and the Finnish Environment Institute.