Wood-derived soil amendments can promote sustainable agriculture

A study carried out at the University of Helsinki has demonstrated that wood-derived soil amendments can increase organic carbon content in arable land and, consequently, improve the growth conditions for plants. They can offer a novel solution for improving agricultural sustainability.

Promoting the sustainability and productivity of agriculture is an important part of future sustainable development. A study recently completed at the University of Helsinki’s Faculty of Agriculture and Forestry demonstrates that soil amendments play a key role in this. According to Doctoral Researcher Kenneth Peltokangas, pulp sludge, biochar and other soil amendments derived specifically from wood can increase the carbon content of arable land, thus improving plant growth conditions. 

“The effects of soil amendments have to do with their porous structure, which improves the soil’s retention of water and nutrients as well as promoting their availability to crops. The ligneous structure is also very durable and can be preserved in the soil for up to decades. This makes wood-derived soil amendments a natural way to bind carbon from the atmosphere to the soil, helping curb climate change,” Peltokangas says.

In addition, biochar and pulp sludge function as liming materials that reduce the acidity of the soil and, consequently, improve the nutrient absorption for plants. Liming is particularly important in Finland, where soil is naturally acidic and requires constant care. Liming also has a comprehensive effect on a soil’s capacity for growth, which is why it can contribute to reducing the environmental impact of arable land. 

“However, soil amendments are not a solution to all agricultural problems, with no direct effects on crop yields observed. At the same time, several positive effects on soil properties indicate that these substances are a safe option for maintaining soil health. In fact, soil amendments could facilitate the sustainability transition by offering farmers a new tool for reducing the environmental impact of agriculture,” Peltokangas notes.

At the moment, the biggest obstacle to the use of soil amendments is their high price. According to Peltokangas, farmers should use them with care to obtain the best possible results in terms of agricultural productivity and environmental sustainability. 

Kenneth Peltokangas wrote his doctoral thesis at the Faculty of Agriculture and Forestry in cooperation with researchers from the University of Helsinki and the Finnish Meteorological Institute as well as parties active in the circular economy. 



Doctoral defence

Kenneth Peltokangas, M.Sc. will defend the doctoral dissertation entitled "Wood-derived soil amendments and their effects on soil fertility and greenhouse gas emissions from cultivated boreal soils" in the Faculty of Agriculture and Forestry, University of Helsinki, on 9 June 2023 at 12:00. The public examination will take place at the following address: Metsätieteiden rakennus, Auditorium 108 (ls B3), Latokartanonkaari 7, Helsinki.

Professor Patrick Faubert, Université du Québec à Chicoutimista, will serve as the opponent, and Mari Pihlatie as the custos.

The dissertation will be published in the series Dissertationes schola doctoralis scientiae circumiectalis, alimentariae, biologicae. Universitatis Helsinkiensis. The dissertation is also available in electronic form in Helda.