Metsä Board and Finnish circular economy company, Soilfood are reusing fiber waste to improve soil quality by recycling wood fiber nutrients back into soil, which stores the fiber wood carbon. 

Soilfood produces wood-based soil improvement fibers from fiber fractions made as side streams at Metsä Board’s cardboard mills. The fibers are said to increase the fertility of the soil and improve its water retention. The use of wood fiber is also an effective method of water conservation as it can reduce the run-off of phosphorus from fields by up to 50%. 

“Together with farmers and our industrial partners, we are replacing virgin raw materials with recycled ones and using natural resources wisely. The demand for recycled nutrients and soil improvement fibers has grown strongly in recent years. The growth is currently limited mainly by the availability of raw materials,” says Sampo Järnefelt, chief commercial officer at Soilfood. 

Side streams against landfill
Soilfood collects two truckloads of side streams from Metsä Board’s mills in Kemi and Äänekoski, Finland, each weekday. In addition to Soilfood’s soil improvement fibers, the side streams from Metsä Board’s mills are being utilized for energy production and landscaping.

Metsä Board’s cooperation with Soilfood started with a research project initiated in 2015 by the Natural Resources Institute Finland to investigate the ability of wood-based fiber sludge for stabilizing the structure of field soil and thus reduce erosion and nutrient leaching from fields to water bodies. These field experiments found soil improvement fibers to reduce the risk of nutrient leaching by up to 50%.

The utilization of side streams is also included in Metsä Board’s 2030 sustainability targets. “Currently, more than 99% of our production side streams are used either as materials or energy. We aim to make 100% use of all production side streams to ensure our processes do not generate landfill waste after 2030,” says Markku Leskelä, development director at Metsä Board.

Side streams can be burned to create energy, but using them as soil improvement fibers is more valuable from a circular economy perspective. The nutrients in the wood-based material are returned to the soil and part of the carbon is stored for the long term. 

Green investments for carbon cuts 
In one treatment cycle, the farmer adds up to five metric tons of carbon to the field, some of which is broken down by biological processes to feed the microbiota of the soil and some sequestered in the soil, forming a carbon storage for more than 20 years.

“Our cooperation with Soilfood is a good example of a circular economy that benefits all parties involved,” says Leskelä.

Meanwhile, the Intergovernmental Panel on Climate Change flagged that global food systems need to dramatically transform if society wants to prevent the earth from warming over 1.5-degrees celsius by 2050 or reverse the heating if it overshoots. Balanced diets with less meat, green investments and crop resilience innovations will be key to slowing down emissions while maintaining agricultural yields that safeguard planetary food security, stressed the panel.

According to the UN Food and Agriculture Organization, food system emissions – from agricultural production, packaging, land use and waste management – accounted for 31% of global emissions in 2020, down from 38% in 2000.

“Renewable energy, energy efficiency, green transport, green urban infrastructure, halting deforestation, ecosystem restoration and sustainable food systems will help to stabilize our climate, reduce nature biodiversity loss and pollution and waste,” asserted UNEP executive director Inger Andersen.