How forest nurseries can reduce nitrogen leaching by up to 80%

Nitrogen leaching from forest nurseries is a known problem. Traditional fertilization leads to large nitrogen nutrient losses that affect plant growth, eutrophication, and harm the environment. Holmen's forest nursery in Gideå, Sweden, is an example of how new technology and sustainable nitrogen solutions can reduce these losses. By using innovative organic nitrogen technology, Holmen has not only dramatically reduced its nitrogen leaching, but also streamlined its working practices and created more robust and sustainable forest plants.

What is nitrogen leaching and why is it a problem?

Forest nurseries rely on nutrients to produce seedlings, but much of the nutrients are leached into the surrounding environment. The use of traditional fertilizers based on ammonium nitrate leads to a large proportion of nitrogen running off and ending up in nearby water bodies. This leads to eutrophication with a range of negative effects such as algae blooms followed by oxygen depletion, but also making the water unfit for drinking. Studies show that nitrogen leaching from forest nurseries can in some cases be as high as 85% of added nitrogen (Hannerz and Rosenberg 2001), which is not only a waste of resources but also a serious environmental impact.

With a total production in Sweden of 450 million forest seedlings per year, this means, in addition to the environmental damage, higher costs for fertilizer and an inefficient use of resources. According to calculations from Skogforsk, the total nitrogen leaching from Swedish forest nurseries in the early 2000s was about 20-25 tons of N per year, given a production then of 300-400 million seedlings. Today, some 50-150 million more seedlings are produced each year, which probably means even greater leaching. This is lower than nitrogen emissions from agriculture, but locally, nitrogen runoff can have a significant impact, for example at a single nursery near a water source or at smaller water bodies and shallow bays. Therefore, the industry continues to strive for more efficient nitrogen use per plant, both for the environment and the economy.

At Holmen's nursery in Gideå, production of pine seedlings is in full swing.

A new approach to nitrogen delivery

By using an innovative organic nitrogen technology based on arginine, Arevo offers a sustainable nitrogen solution to reduce leaching in cultivation. The nitrogen in the products effectively binds to soil particles and the roots of the plants are a very efficient system for taking up the bound nitrogen. This allows the plants to take up more of the applied nutrients, reducing leaching into the environment. It also improves the root development of the plants. This method makes the plants more robust, making it easier for them to be planted out in the forest and establish themselves well.

Holmen Gideå - A success story

Holmen's forest nursery in Gideå is a good example of how this technique can be applied in practice. After identifying the problems of nitrogen leaching and inefficient fertilization, Holmen started testing a new nutrient solution already about 20 years ago. By using this technology, Holmen has managed to reduce its nitrogen leaching by more than 80%, which means both environmental benefits and less waste of resources.

The diagram shows the difference in nitrogen loss to the drainage water at a nursery when using conventional fertilizer compared to arginine-based nutrition for growing pine seedlings.

We measure the nursery's emissions twice a year, in spring and in fall. We have seven sampling points where we collect runoff water from wells and we also take surface water samples from the nearby river. The samples are then sent to analysis labs for control. We have not had any deviations," says Ingela Toljamo, Cultivation Specialist at Holmen's nurseries.

Results from Holmen's forest nursery in Gideå

The experience from Gideå shows the benefits of precision nutrition. Nitrogen leaching has been almost completely eliminated, and the amount of nitrogen used is significantly lower than before. The conversion has not only reduced the negative impact on the surrounding ecosystem and the water bodies used for drinking water, but also led to stronger plants with better root development. This makes the plants more resilient and improves their chances of establishing themselves in the forest.

Another advantage of the organic nitrogen-based nutrient is that it can be applied according to a fixed schedule. Holmen applies nutrients once a week and does not need to adjust the application in case of rainfall, saving both time and resources. This makes the work more efficient, while reducing the risk of eutrophication in surrounding waterways.

"We apply nutrients once a week. You don't need any special skills to learn how to feed the plants because it's done on a schedule. It's actually easier than doing the actual watering, which requires more dexterity," says Fanny Berglund, cultivation manager in Gideå.

Tanks with Arevo Shoot connected to the irrigation system.

The future of sustainable farming

The success in Gideå shows that it is possible to reduce nitrogen emissions and at the same time get better results both for the plants and for efficiency, and Holmen has long been using Arevo's products at the nursery in Friggesund. By using precision nutrition, forest nurseries, as well as other actors in agriculture and horticulture, can grow in a more sustainable way.

Reference list

• Skogforsk (2020). More efficient nutrient supply in nurseries - How can nitrogen emissions be reduced? [Skogforsk Article].

• SLU (2019). Eutrophication from forestry and nurseries - A growing challenge[Report from the Swedish University of Agricultural Sciences].

• EU (2021). Farm to Fork Strategy - Reducing nitrogen emissions and nutrient leaching by 2030[European Commission].

• Skogforsk (2001), Work report 480: "Nutrient utilization and leaching in practical plant cultivation " - nutrient balance measurements in cover and bare root nurseries

• Skogforsk Plantaktuellt no. 1 2004 - trials with needs-adapted fertilization of spruce (Lars Rytter)

• Skogforsk Kunskapsbanken (1986/2019) - articles on fertilization in the nursery and field

• Research/SLU - T. Näsholm et al, uptake of organic nitrogen (arginine)

• Holmen Skog (2018), press info - introduction of Argrow arginine fertilizer

• As well as collected data from industry players such as Holmen, SCA; and the Swedish Forest Agency's recommendations and theses on supplementary fertilization