The Norwegian way to phosphorus recycling

A circular use of phosphorus could reduce the environmental and economic risks of its dispersion, a report by the Norwegian University of Science and Technology in Trondheim explains

by Matteo Cavallito

 

Capturing and recycling phosphorus could help reduce risks in terms of availability and pollution. This is particularly relevant for Norway, whose government plans to expand salmon and trout production to 5 million tonnes annually from the current 1.5 million by 2050. This is the message from a new report by the Norwegian University of Science and Technology in Trondheim, which emphasises the crucial role of phosphorus in national agriculture and aquaculture.

“Currently, large amounts of phosphorus enter the Norwegian food system from abroad in the form of mineral fertilizer, feedstuff, food, as well as micro-ingredients for animal feed, mainly in salmon farming,” the report explains.”However, only a small fraction of this phosphorus ends up as food for humans, while the largest part accumulates in soil and water systems.”

A circular solution for phosphorus

“Many decades of overfertilization has led to a build-up of phosphorus in the soil, but also to high concentrations of phosphorus in the Norwegian water system,” explains Miguel Las Heras Hernández, a researcher at the Norwegian Institute for Air Research (NILU) and co-author of the report in a note from the Trondheim University. The result is a number of environmental hazards including dispersion by leaching from the soil into water systems and the risk of eutrophication, the excessive accumulation of nutrients in the soil.

In this scenario, the report argues, a more sustainable use of the element could reduce these risks. Creating a circular economy for phosphorus, however, is a complex task. For at least three reasons.

Firstly, the scientists explain, land- and sea-based food systems are increasingly interconnected (as shown, for example, by agricultural feed production or the application on land of so-called fish sludge, the residues of aquaculture that are also rich in nitrogen and therefore used as fertilisers). Moreover, the Norwegian phosphorous cycle is increasingly linked to that of other countries, with trade flows increasing. Finally, phosphorous fertilisers are often contaminated with heavy metals such as cadmium, uranium and zinc, which also tend to accumulate in the soil, making remediation necessary.

Four recommendations

Carried out as part of the MIND-P project, dedicated to the study of the Norwegian phosphorus cycle, the report then suggests four strategies to effectively manage phosphorus in a circular manner. Namely:

1. Develop and maintain a national nutrient accounting system.
2. Minimise losses of the element.
3. Create infrastructure to capture, process, trade and utilise manure and fish sludge to produce high quality recycled fertilisers.
4. Adopt a regulatory framework to promote a market for these products.

Today five countries control 80% of the reserves

The inefficiencies associated with the linear soil economy do not only appear on an environmental basis. Also significant are the economic impacts in terms of the availability of a resource that remains highly concentrated in a few producing countries. More than 80 per cent of global phosphate rock reserves, in fact, are owned by just five nations: around 70 per cent are located in Morocco and the occupied Western Sahara.

This oligopoly ‘The high concentration renders many countries vulnerable to geopolitical and economic instabilities and threatens food safety,’ the report continues, recalling how, not surprisingly, the EU has placed the element on its list of Critical Raw Materials.

The problem is not new. Last year, a study by INRAE, the Institut national de la recherche agronomique, a French government body, and Bordeaux Sciences Agro, a training school of the local university, pointed out how under these conditions current agricultural models end up creating great stress on the market and production, creating the conditions for new problems in the future. “At current rates of extraction,” the researchers explain, “we will likely reach peak phosphorus (the point of maximum resource production) by 2050. Such will probably lead to an increase in fertiliser prices and greater geopolitical tensions.”