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The Baltic Sea suffers from eutrophication, with part of the nutrient emissions originating from agriculture. The SuMaNu project coordinated by Luke established recommendations for more sustainable use of manure and nutrients in the Baltic Sea Region.

According to Research Scientist Minna Sarvi and Principal Research Scientist Sari Luostarinen from Natural Resources Institute Finland (Luke), the connection between nitrogen and phosphorus emissions from agriculture, forestry, industry and municipalities and the eutrophication of water systems were recognised decades ago. Significant measures have been taken to reduce emissions since the 1980s.

Nitrogen and phosphorus emissions from industry and municipalities have been significantly reduced through improvements in wastewater treatment, for example. However, diffuse pollution remains a problem, with much of it originating from agriculture.

Diffuse pollution accounts for approximately half of the nutrient load to the Baltic Sea. It is expected to increase further if climate change leads to higher precipitation and mild winters. This would also increase the risk of nutrient leaching from fields,” Sarvi says.

Phosphorus and nitrogen that end up in the Baltic Sea promote the growth of algae and cyanobacteria, increase the turbidity of seawater and threaten the biodiversity of the marine ecosystem. Emissions cause changes in animal and plant species, lead to fish deaths and increase the risk of oxygen depletion. In oxygen-depleted conditions, phosphorus accumulated in seabed sediments may be released, which further accelerates eutrophication.

Making nutrient use more efficient

Luke has carried out numerous research and development projects aimed at reducing nutrient emissions from agriculture. Funded by various parties, the projects have shared the common goal of making nutrient use more efficient and finding solutions for nutrient recycling. One of the recent projects developed a nutrient calculator for assessing the availability and use of and the need for organic nutrient-rich biomasses in Finland. Luke has engaged in wide-ranging cooperation in these projects with international and domestic partners.

“If a farm or a region has more manure than is needed, it may end up fertilising fields more than is necessary. The key is to first determine the nutrient content of the soil and the actual fertilisation needs of crops. This reveals the need for additional nutrients using fertilisers. Nutrient leaching can also be partially prevented by keeping field soils in good condition and through effective water management. Wide-ranging measures reduce nutrient load and thereby help prevent eutrophication,” Luostarinen explains.

One of Luke’s most recent projects is the SuMaNu project funded by the Interreg Baltic Sea Region Programme. The three-year project, which ended in September, involved participants from seven Baltic Sea countries as well as the Baltic Marine Environment Protection Commission HELCOM.

This international project compiled results from previous international projects. Based on the results, we created international recommendations for more sustainable use of manure and nutrients,” says Sarvi, who served as Project Coordinator.

Surplus must be recycled

The SuMaNu project’s list of action proposals includes both farm-level and region-level recommendations. Animal farms are instructed to implement the entire manure management chain, from animal feeding to the collection, storage and field application of manure, in such a way as to minimise nutrient emissions. The recommendations emphasise the importance of taking crop-specific fertiliser limits, the nutrient content of manure and the nutrient content of the soil into account in addition to optimising the timing of manure application.

If a farm’s nutrient balance is at a surplus, the excess nutrients should be reallocated to nearby farms or farms located in a different region.

“If a region has an excess of nutrients in biomasses, part of it should be transferred to regions in need for the nutrients. This would reduce the risk of nutrient leaching in domestic animal production and the use of manure could replace the use of commercial fertilisers. Such region of concentrated animal production exists in several countries around the Baltic Sea. In Finland, there is a need to reallocate manure from Ostrobothnia to Central Finland, for example. To improve transportability, manure should be processed into more concentrated fertiliser products. However, this processing requires the implementation of expensive technologies and the creation of a market for the new products. This can only be achieved if society provides economic incentives for it,” Luostarinen says.

A healthy Baltic Sea can only be accomplished through international cooperation. HELCOM has made use of the recommendations compiled in the SuMaNu project during its work to update the Baltic Sea Action Plan.

The Action Plan defines a broad range of recommendations and obligations aimed at protecting the Baltic Sea through reducing eutrophication, for example. The SuMaNu recommendations also support the EU’s shared goal of halving nutrient emissions from agriculture and reducing fertiliser use by a fifth by 2030.

Bringing nutrient use under control

  • The SuMaNu project coordinated by Luke promoted the sustainable use of manure and nutrients in agriculture in the Baltic Sea region.
  • The main objective was to make more effective use of recycled nutrients and reduce nutrient loss from agriculture to the Baltic Sea.
  • International recommendations were created in the project for more sustainable use of manure and nutrients.More information from SuMaNu’s website.

Luken koordinoiman SuMaNu-hankkeen logoja.

Text: Tuomas I. Lehtonen
Photo: iStock

A Finnish version of this article was released in the Climate Publication published in Helsingin Sanomat newspaper November 3rd 2021. The Climate Puplication was produced by Content House.