1,4,- 1University of Natural Resources and Life Sciences Vienna, Institute of Soil Research , Department of Forest and Soil Science, Austria (celia.fernandez-balado@boku.ac.at)
- 2Agroscope, Agroecology and Environment, Zurich, Switzerland
- 3Lithuanian Research Centre for Agriculture and Forestry, Institute of Agriculture, Kėdainiai, Lithuania
- 4Biogeoquímica, Ecología Vegetal y Microbiana, Instituto de Recursos Naturales y Agrobiología de Sevilla, CSIC, Sevilla, Spain
Agricultural management measures that promote carbon sequestration in soils are essential for both climate change mitigation and adaption. Crop roots are the primary source of soil organic carbon (SOC) as belowground carbon (C) inputs —namely root biomass C and rhizodeposition C— persist in soil longer than C derived from above ground crop residues and organic soil amendments and they explore deeper soil layers. Therefore, selecting varieties of main crops with increased belowground C (BGC) inputs has been proposed as a viable option to enhance SOC stocks without compromising yield.
Despite this potential, there is limited understanding of how root biomass C and rhizodeposition C vary among modern commercial crop varieties. Moreover, data are lacking on how these belowground C inputs are influenced by diverse pedoclimatic conditions, and few studies assess C allocation in deep soil layers.
To address this gap, we implemented an in situ multiple-pulse ¹³CO₂ labeling experiment with four commercially relevant winter wheat (WW) varieties, which were selected based on a previous study with 10 varieties on 11 European sites (Heinemann et al., 2025). This replicated field study was carried out across four European countries—Austria, Lithuania, Spain, and Switzerland—to quantify net belowground C inputs after harvest. The WW varieties were isotopically labelled multiple times during their active growth phase. Following harvest, soil and roots were sampled using soil coring to a depth of 1 m. Bulk isotope analysis was performed on soil and each root fraction to quantify net rhizodeposition C.
Results show mean total BGC inputs across all sites and varieties of 1.59 ± 0.07 Mg ha-1. Rhizodeposition C accounted for 55% of total BGC, peaking in the 15–30 cm soil layer, which contained 81% of total BGC. After accounting for site effects, varieties showed different belowground carbon allocation strategies: some varieties exhibited relatively greater allocation to root biomass, whereas others showed comparatively higher rhizodeposition.
Our results will also integrate aboveground biomass and grain yield data to assess whether selecting specific genotypes can simultaneously support food production and enhance SOC build up.
Note: This study was part of the European Joint Programme on Soil (EJP Soil) project MaxRoot-C.
REFERENCES
Heinemann, Henrike, et al. "Optimising Root and Grain Yield Through Variety Selection in Winter Wheat Across a European Climate Gradient." European Journal of Soil Science 76.2 (2025): e70077. https://doi.org/10.1111/EJSS.70077
How to cite: Fernández Balado, C., Juchli, T., Toleikiene, M., Veršulienė, A., Hirte, J., Mayer, J., González Pérez, J. A., and Hood-Nowtony, R.: Is it possible to enhance belowground carbon inputs to soil through variety selection? A Case Study in Winter Wheat Using a ¹³CO₂ Multiple-Pulse Labelling Approach, EGU General Assembly 2026, Vienna, Austria, 3–8 May 2026, EGU26-21537, https://doi.org/10.5194/egusphere-egu26-21537, 2026.
