Rewetting alongside biochar and sulphate addition mitigates greenhouse gas emissions and retain carbon in degraded upland peatlands

Jeewani, Peduruhewa H.; Brown, Robert W.; Evans, Chris D.; Cook, Jack; Roberts, Benjamin P.; Fraser, Mariecia D.; Chadwick, David R.; Jones, Davey L.

Rewetting alongside biochar and sulphate addition mitigates greenhouse gas emissions and retain carbon in degraded upland peatlands

Jeewani, Peduruhewa H. ORCID: https://orcid.org/0000-0001-8883-9887; Brown, Robert W. ORCID: https://orcid.org/0000-0001-9119-6130; Evans, Chris D. ORCID: https://orcid.org/0000-0002-7052-354X; Cook, Jack ORCID: https://orcid.org/0009-0004-3811-5433; Roberts, Benjamin P. ORCID: https://orcid.org/0000-0003-0329-2515; Fraser, Mariecia D. ORCID: https://orcid.org/0000-0003-3999-1270; Chadwick, David R. ORCID: https://orcid.org/0000-0002-8479-8157; Jones, Davey L. ORCID: https://orcid.org/0000-0002-1482-4209. 2025 Rewetting alongside biochar and sulphate addition mitigates greenhouse gas emissions and retain carbon in degraded upland peatlands. Soil Biology and Biochemistry, 207, 109814. 11, pp. 10.1016/j.soilbio.2025.109814

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Official URL: https://doi.org/10.1016/j.soilbio.2025.109814

Abstract/Summary

Peat soils store significant amounts of carbon (C) globally, and increased C sequestration into peatlands could play a role in offsetting anthropogenic greenhouse gas (GHG) emissions. As such, there is a need to find and assess optimal greenhouse gas removal (GGR) interventions to minimise GHG losses, protect current C stocks, and promote further C sequestration. This mesocosm study assessed the additional C storage potential of different C-rich substrates (Juncus straw or Juncus-derived biochar) and/or FeSO4 amendments, with a low water table (LW; −15 cm) and high-water table (HW; 0 cm) in intact soil columns (20 cm diam. x 25 cm deep) extracted from degraded upland peat. GHG fluxes, soluble nutrients, changes in microbial community structure and enzyme activity were measured over a one-year period to evaluate the net C storage and their overall GGR potential. HW reduced CO2 emissions by 28 % compared to LW, while CH4 emissions increased, ultimately contributing 61 % of the overall CO2 equivalent (CO2eq) GHG emissions in HW cores with no amendments. Organic amendments had a significant effect on CO2 and CH4 emissions with the highest cumulative emissions being from the Straw-HW (26.2 t CO2eq ha−1 yr−1) and the lowest cumulative emissions being from the Biochar + FeSO4+HW (7.9 t CO2eq ha−1 yr−1). Biochar + FeSO4+HW led to the strongest net gain in soil C, suppressing decomposition of the native peat-C as well as CH4 emissions. The application of FeSO4 significantly reduced CO2eq GHG emissions by preventing methanogenesis through alternative electron acceptors. The Biochar + HW treatment suppressed Ascomycota abundance by 22 %. The combination of a high-water level, biochar addition and availability of alternative electron acceptors (e.g., FeSO4) can increase net C accumulation and GGR via both abiotic and biotic mechanisms, including i) increased C input, ii) modulation of soil microbiome to reduce peat turnover; and iii) suppression of CH4 and N2O emissions.

Item Type:

Publication - Article

Digital Object Identifier (DOI):

10.1016/j.soilbio.2025.109814

UKCEH and CEH Sections/Science Areas:

Land-Atmosphere Interactions (2025-)

ISSN:

0038-0717

Additional Keywords:

carbon sequestration, greenhouse gas removals, soil biodiversity, methane, enzymes

NORA Subject Terms:

Ecology and Environment
Agriculture and Soil Science
Atmospheric Sciences