Unleashing the sequestration potential of soil organic carbon under climate and land use change scenarios in Danish agroecosystems

• Published in: The Science of the total environment Vol. 905; p. 166921
• Main Authors: Gutierrez, Sebastian, Grados, Diego, Møller, Anders B., de Carvalho Gomes, Lucas, Beucher, Amélie Marie, Giannini-Kurina, Franca, de Jonge, Lis Wollesen, Greve, Mogens H.
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 20-12-2023
• Subjects: Data-based model; Digital soil mapping; Process-based model; SOC stabilization; Soil carbon deficit; Soil health; Soil carbon deficit; SOC stabilization; Digital soil mapping; Data-based model; Process-based model; Soil health
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2023.166921

Future global climate changes are expected to increase soil organic carbon (SOC) decomposition. However, the combined effect of C inputs, land use changes, and climate on SOC turnover is still unclear. Exploring this SOC-climate-land use interaction allows us to understand the SOC stabilization mechanisms and examine whether the soil can act as a source or a sink for CO2. The current study estimates the SOC sequestration potential in the topsoil layer of Danish agricultural lands by 2038, considering the effect of land use change and future climate scenarios using the Rothamsted Carbon (RothC) model. Additionally, we quantified the loss vulnerability of existing and projected SOC based on the soil capacity to stabilize OC. We used the quantile random forest model to estimate the initial SOC stock by 2018, and we simulated the SOC sequestration potential with RothC for a business-as-usual (BAU) scenario and a crop rotation change (LUC) scenario under climate change conditions by 2038. We compared the projected SOC stocks with the carbon saturation deficit. The initial SOC stock ranged from 10 to 181 Mg C ha−1 in different parts of the country. The projections showed a SOC loss of 8.1 Mg C ha−1 for the BAU scenario and 6 Mg C ha−1 after the LUC adoption. This SOC loss was strongly influenced by warmer temperatures and clay content. The proposed crop rotation became a mitigation measure against the negative effect of climate change on SOC accumulation, especially in sandy soils with a high livestock density. A high C accumulation in C-saturated soils suggests an increase in non-complexed SOC, which is vulnerable to being lost into the atmosphere as CO2. With these results, we provide information to prioritize areas where different soil management practices can be adopted to enhance SOC sequestration in stable forms and preserve the labile-existing SOC stocks.
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•First-national map of soil organic carbon sequestration potential for Denmark at 1 km resolution.•Climate change leads up to soil organic carbon loss by 2038 in Danish agroecosystems.•Perennial grasses in rotation with annual crops promote the soil organic carbon sequestration.•Soil organic carbon sequestration strategies must take organic carbon saturation level into account.