Is biochar addition an effective and environmentally safe solution for soil remediation and improvement of soil quality?

The present project intended to establish international cooperation in the research of biochar. Biochar is a product of pyrolysis of biomass that is progressively recognized as a valuable tool for soil remediation and for the enhancement of soil quality. While the research on interactions between biochar and soil pollutants has been extensive during the last years, effects on soil biota have been rather overlooked. The present project is focused on the biological effects of biochar using the nematode Caenorhabditis elegans as a representative of soil microfauna. Toxicity test with C.elegans were performed in a range of non-contaminated to contaminated soils amended with biochar at increasing doses in order to determine the maximum and minimum application doses (Max/MinADs) that can be added to soils without compromising soils´ ecological functions (MaxAD) or that should be added to soils to provide a sufficient remediation effect (MinADs). The main findings suggest that biochar up to the dose of 10-20% in soil does not have serious detrimental effects on C.elegans. Significant remediation effects were observed at doses of > 10% of biochar in soil. Apart from the toxicity effects on nematodes, the exposure concentration of soil pollutants to nematodes was quantified using a passive sampling method and compared with the toxicity data. The comparison suggests that nematodes are exposed to toxicants both via porewater and contaminated food. The findings further revealed that more information is needed on factors such as food density and length of exposure to fully understand and reliably predict the interactions between biochar, soil pollutants and toxicants. The results gained within this research project represent very well structured and primary data that will be used a basis of further cooperation on research projects. Apart from the scientific goals, EU strategic goals were tackled within this project including promoting research cooperation across borders, increasing the number of internationally co-authored scientific publications, increasing the mobility of researchers, contributing to gender equality and inclusion of young scientists (< 35), strengthening the dialogues and research between international partners on societal challenges such as food production, soil quality and health, and climate change, development of international partnerships on the basis of common interest, mutual benefit, and synergy, and improving the research quality and knowledge transfer.