Inducing inorganic carbon accrual in subsoil through biochar application on calcareous topsoil

Wang Yang, Joseph Stephen, Wang Xiang, Weng Zhe H., Mitchell David R.G., Nancarrow Mitchell, Taherymoosavi Sara, Munroe Paul, Li Guitong, Lin Qimei, Chen Qing, Flury Markus, Cowie Annette, Husson Olivier, van Zwieten Lukas, Kuzyakov Yakov, Lehmann Johannes, Li Baoguo, Shang Jianying. 2023. Inducing inorganic carbon accrual in subsoil through biochar application on calcareous topsoil. Environmental Science and Technology, 57 (4) : 1837-1847.

Liste HCERES des revues (en SHS) : oui

Thème(s) HCERES des revues (en SHS) : Psychologie-éthologie-ergonomie

Résumé : Biochar amendments add persistent organic carbon to soil and can stabilize rhizodeposits and existing soil organic carbon (SOC), but effects of biochar on subsoil carbon stocks have been overlooked. We quantified changes in soil inorganic carbon (SIC) and SOC to 2 m depth 10 years after biochar application to calcareous soil. The total soil carbon (i.e., existing SOC, SIC, and biochar-C) increased by 71, 182, and 210% for B30, B60, and B90, respectively. Biochar application at 30, 60, and 90 t ha–1 rates significantly increased SIC by 10, 38, and 68 t ha–1, respectively, with accumulation mainly occurring in the subsoil (below 1 m). This huge increase of SIC (mainly CaCO3) is ∼100 times larger than the inorganic carbon present in the added biochar (0.3, 0.6, or 0.9 t ha–1). The benzene polycarboxylic acid method showed that the biochar-amended soil contained more black carbon particles (6.8 times higher than control soil) in the depth of 1.4–1.6 m, which provided the direct quantitative evidence for biochar migration into subsoil after a decade. Spectral and energy spectrum analysis also showed an obvious biochar structure in the biochar-amended subsoil, accompanied by a Ca/Mg carbonate cluster, which provided further evidence for downward migration of biochar after a decade. To explain SIC accumulation in subsoil with biochar amendment, the interacting mechanisms are proposed: (1) biochar amendment significantly increases subsoil pH (0.3–0.5 units) 10 years after biochar application, thus forming a favorable pH environment in the subsoil to precipitate HCO3–; and (2) the transported biochar in subsoil can act as nuclei to precipitate SIC. Biochar amendment enhanced SIC by up to 80%; thus, the effects on carbon stocks in subsoil must be understood to inform strategies for carbon dioxide removal through biochar application. Our study provided critical knowledge on the impact of biochar application to topsoil on carbon stocks in subsoil in the long term.

Mots-clés Agrovoc : carbone, sous-sol, sous solage, sous soleuse, amendement minéral, carbone organique du sol, amendement organique, charbon de bois, séquestration du carbone, cycle du carbone, sol calcaire, carbone inorganique

Mots-clés libres : Biochar, Inorganic carbon

Classification Agris : P33 - Chimie et physique du sol
F04 - Fertilisation

Champ stratégique Cirad : CTS 2 (2019-) - Transitions agroécologiques

Agences de financement hors UE : National Natural Science Foundation of China, China Agricultural Research System, Ministry of Finance, Rural Affairs, RUDN University

Auteurs et affiliations

• Wang Yang, CAU [China Agricultural University] (CHN)
• Joseph Stephen, UNSW Sidney (AUS)
• Wang Xiang, CAU [China Agricultural University] (CHN)
• Weng Zhe H., University of Queensland (AUS)
• Mitchell David R.G., University of Wollongong (AUS)
• Nancarrow Mitchell, University of Wollongong (AUS)
• Taherymoosavi Sara, UNSW Sidney (AUS)
• Munroe Paul, UNSW Sidney (AUS)
• Li Guitong, CAU [China Agricultural University] (CHN)
• Lin Qimei, CAU [China Agricultural University] (CHN)
• Chen Qing, CAU [China Agricultural University] (CHN)
• Flury Markus, Washington State University (USA)
• Cowie Annette, University of New England (AUS)
• Husson Olivier, CIRAD-PERSYST-UPR AIDA (FRA) ORCID: 0000-0001-9587-5819
• van Zwieten Lukas, Wollongbar Primary Industries Institute (AUS)
• Kuzyakov Yakov, University of Göttingen (DEU)
• Lehmann Johannes, Cornell University (USA)
• Li Baoguo, CAU [China Agricultural University] (CHN)
• Shang Jianying, CAU [China Agricultural University] (CHN) - auteur correspondant

Source : Cirad-Agritrop (https://agritrop.cirad.fr/603269/)

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