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The productivity effects of macroalgal biochar from Ulva (Linnaeus) bloom species on Arabidopsis thaliana (Linnaeus) seedlings

Kenneth, Finlay; Joniver, Catherine F.H.; Meredith, William; Adams, Jessica M.M.

The productivity effects of macroalgal biochar from Ulva (Linnaeus) bloom species on Arabidopsis thaliana (Linnaeus) seedlings Thumbnail


Finlay Kenneth

Catherine F.H. Joniver

Jessica M.M. Adams


Intensive agricultural practices and poor management of organic waste have adverse effects on aquatic ecosystems, where excessive macroalgal proliferation can occur to form ‘green tides’, with negative environmental, ecological and socioeconomic impacts. One novel method for converting a problematic material into a valuable resource is to use excess algal biomass as a feedstock for biochar production. With a high elemental composition, such a resource might be suitable to redress soil deficiencies and to ameliorate soil fertility. Green macroalgae from the Ulva genus, in bladed (predominantly U. rigida), tubular (predominantly U. prolifera) and mixed morphological (U. rigida and U. prolifera) phenotypes, were used to produce biochars. A pot trial within a controlled-environment chamber was carried out to determine the effects of amending high- and low-fertilizer compost with algal biochars (applied at 0, 0.5, 1, 2 and 5% w/w) on the growth rate of Arabidopsis thaliana. A commercial wood-based biochar was used under similar treatments as a control. Weekly imaging and final harvest weights provided additional growth data; composition data including ultimate and proximate analyses, pH, Brunauer–Emmett–Teller (BET) surface area and hydropyrolysis of the dried macroalgae and algal biochars were also conducted. Significant enhanced growth in seedlings grown with biochar amendment were not observed in high- or low-fertilizer compost, and the addition of algal biochars at 5% w/w to high-fertilizer soil significantly reduced plant growth. Elemental analysis revealed that the algal biochars contained high quantities of alkaline elements including sodium. It was hypothesised that salinity was the primary factor affecting plant growth at higher biochar application rates, despite the algae being sourced from an estuarine environment. Biochar provenance and composition is highly significant: using the catch-all term ‘biochar’ ignores both the range of materials and composition that could be used to create it and its subsequent impact within the soil. HIGHLIGHTS First plant trial using biochar predominantly from Ulva species. Negative impact seen with 5% algal biochar on plant growth. High sodium concentrations putatively identified as reduced plant growth cause.


Kenneth, F., Joniver, C. F., Meredith, W., & Adams, J. M. (2023). The productivity effects of macroalgal biochar from Ulva (Linnaeus) bloom species on Arabidopsis thaliana (Linnaeus) seedlings. European Journal of Phycology, 58(3), 284-299.

Journal Article Type Article
Acceptance Date Jul 15, 2022
Online Publication Date Aug 23, 2022
Publication Date 2023
Deposit Date Aug 25, 2022
Publicly Available Date Aug 25, 2022
Journal European Journal of Phycology
Print ISSN 0967-0262
Electronic ISSN 1469-4433
Publisher Informa UK Limited
Peer Reviewed Peer Reviewed
Volume 58
Issue 3
Pages 284-299
Keywords Plant Science, Aquatic Science
Public URL
Publisher URL