Wood-derived organic soil amendments have positive climate impacts

Article: Effects of biochar and ligneous soil amendments on greenhouse gas exchange during extremely dry growing season in a Finnish cropland

Authors: Kulmala, Liisa et al.

Publication: Frontiers in Sustainable Food Systems

Year: 2022

The study researched the climate impacts of ligneous soil amendments obtained from the side streams of the pulp industry. Three soil amendments were studied: lime-stabilized fiber from the pulp industry, willow biochar and spruce biochar. These are economically important biomasses, and it is possible to increase their use in Finnish agricultural lands.

The study compared greenhouse gas exchange, plant growth and soil properties two years after introducing the soil amendments. The experimental fields were of a clay soil cultivated with oat at the Qvidja farm. The plots with soil amendments were compared against fertilized and non-fertilized controls.

Overall, the studied soil amendments indicated positive climatic impact.

The tested soil amendments were found to increase porosity and the mean soil water holding capacity, which was most noticeable in plots amended with spruce biochar. The mean yield and overall biomass production were usually larger in plots with soil amendments; however, the difference was seldom significant due to high variance of crops and biomass production inside duplicate plots.

The measurements coincided with an exceptionally hot and dry summer in 2018, with reduced carbon dioxide and methane exchange rates between the field and the atmosphere, probably due to the weather conditions. But no differences could be found between the amended and unamended treatments. The nitrous oxide emissions were significantly smaller from the soil amended with willow biochar compared with the unamended control plots.