Mosquera, Gundale, et al (2024) Biochar as a potential tool to mitigate nutrient exports from managed boreal forest: A laboratory and field experiment. GCB Bionergy. https://doi.org/10.1111/gcbb.13131

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Forestry activities in drained peatlands can harm water quality by increasing the export of organic matter and nutrients. To address this issue, researchers have explored the potential of biochar, a carbon-rich product, in water purification. Biochar has demonstrated strong adsorption capacity for organic and inorganic nutrients in laboratory settings due to its porous structure and ion-exchange capabilities.

In a 10-day laboratory experiment, researchers evaluated two biochar feedstocks (wood- and garden residue-based) using runoff water from drainage ditches in clear-cut peatland forests. While wood-based biochar efficiently adsorbed total dissolved nitrogen (TDN) and dissolved organic carbon (DOC) in the laboratory, it released phosphate (PO4). Field experiments confirmed that biochar filters reduced TDN and DOC concentrations in water, although the percentage decrease varied based on initial nutrient concentrations.

Considering that 15% of peatland areas in Sweden are affected by forestry, finding scalable tools to counteract negative water quality impacts is crucial. Biochar, derived from various feedstocks, shows promise in mitigating nutrient export from catchments. Importantly, the study suggests a circular system where nutrients captured by biochar filters could be applied back to the forest as a soil amendment, closing the nutrient cycle.

However, challenges exist, such as the effectiveness of biochar in fluctuating field conditions and the need to understand its limitations. The study emphasizes the importance of assessing biochar’s effectiveness in real-world scenarios, considering factors like weather conditions and nutrient fluctuations. Overall, biochar emerges as a potential sustainable solution for water protection in drained peatland forests, with further research needed to refine its application and address challenges.

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