Biochar and Hydrochar from Organic Side-Streams Induce Species-Specific Responses in Plants
Hagner, Marleena; Salmela, Matti J.; Ahmadi, Sajad; Kimbi Yaah, Velma; Ojala, Satu; Laitinen, Tiina; Hiltunen, Lea H. (2025-06-26)
Springer
26.06.2025
Hagner, M., Salmela, M.J., Ahmadi, S. et al. Biochar and Hydrochar from Organic Side-Streams Induce Species-Specific Responses in Plants. J Soil Sci Plant Nutr (2025). https://doi.org/10.1007/s42729-025-02529-2
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© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
https://creativecommons.org/licenses/by/4.0/
© The Author(s) 2025. This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
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Julkaisun pysyvä osoite on
https://urn.fi/URN:NBN:fi:oulu-202507045067
https://urn.fi/URN:NBN:fi:oulu-202507045067
Tiivistelmä
Abstract
Biochar (BC) and hydrochar (HC) have gained attention as multipurpose materials for soil improvement, plant growth promotion, carbon removal and waste reduction – key components of the circular economy. Heterogeneous side-stream and waste biomasses together with thermochemical processes produce variable char products whose effects on soil properties and plants may be divergent and dependent on the environmental context. We produced BC and HC from demolition wood, tomato leaves and biogas digestate and characterized chemical and physical properties of feedstock materials and char products. Growth chamber experiments were established to evaluate the phytotoxicity of the char products and their effects on seedling emergence, biomass and nutrient concentrations in three crop indicator species (barley, radish and rape) grown in a boreal soil. We found that both slow pyrolysis and hydrothermal carbonization (HTC) produce mostly good-quality char products within the limits of the EU Fertilising Products Regulation (FPR) 2019/1009. The effects of BC and HC applications on soil properties reflected the characteristics of the char products and application rates. In general, all char treatments increased soil pH, carbon content and organic matter. Effects of char products on emergence and growth depended on the plant species, sowing time, char treatment and application rate, with many interactive effects of treatments. Immediate phytotoxicity was shown by the highest application rate (50 t ha−1) of tomato BC which reduced emergence in all species. Overall, char application had explicit positive effects on biomass in barley only. Our results suggest that pyrolysis and HTC are valuable methods in processing different side-stream and waste materials into char products that are potential soil amendments. Harmful effects of char application are rare with high-quality products, but the observed patterns of short-term plant responses emphasize the need for environment- and species-specific testing of soil amendments.
Biochar (BC) and hydrochar (HC) have gained attention as multipurpose materials for soil improvement, plant growth promotion, carbon removal and waste reduction – key components of the circular economy. Heterogeneous side-stream and waste biomasses together with thermochemical processes produce variable char products whose effects on soil properties and plants may be divergent and dependent on the environmental context. We produced BC and HC from demolition wood, tomato leaves and biogas digestate and characterized chemical and physical properties of feedstock materials and char products. Growth chamber experiments were established to evaluate the phytotoxicity of the char products and their effects on seedling emergence, biomass and nutrient concentrations in three crop indicator species (barley, radish and rape) grown in a boreal soil. We found that both slow pyrolysis and hydrothermal carbonization (HTC) produce mostly good-quality char products within the limits of the EU Fertilising Products Regulation (FPR) 2019/1009. The effects of BC and HC applications on soil properties reflected the characteristics of the char products and application rates. In general, all char treatments increased soil pH, carbon content and organic matter. Effects of char products on emergence and growth depended on the plant species, sowing time, char treatment and application rate, with many interactive effects of treatments. Immediate phytotoxicity was shown by the highest application rate (50 t ha−1) of tomato BC which reduced emergence in all species. Overall, char application had explicit positive effects on biomass in barley only. Our results suggest that pyrolysis and HTC are valuable methods in processing different side-stream and waste materials into char products that are potential soil amendments. Harmful effects of char application are rare with high-quality products, but the observed patterns of short-term plant responses emphasize the need for environment- and species-specific testing of soil amendments.
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