Posted by Design Studio
26 September 2025
Challenge 2: Soil Carbon
https://onlinelibrary.wiley.com/doi/10.1111/gcb.70450
Harnessing Plant Genetics to Influence Soil Carbon Storage
Plants play a central role in regulating soil organic carbon (SOC) dynamics. With growing interest in land-based carbon dioxide removal, breeding or engineering crops to enhance SOC storage presents a promising climate mitigation strategy. However, the specific plant traits that influence different soil organic matter (SOM) pools remain poorly understood.
A Unique Genetic Common Garden Approach
To investigate plant controls on SOC, researchers analyzed 24 genotypes from a 13-year-old Populus trichocarpa common garden in northwestern Oregon. This long-term, genetically diverse planting allowed the team to decouple biological effects on SOC from environmental and management variability — a rare opportunity in field settings.
Substantial Genotypic Influence on SOC Pools
Soil fractionation revealed wide variation in mineral-associated organic matter (MAOM; 18–67 t C/ha) and particulate organic matter (POM; 2–22 t C/ha). Tree genotype accounted for 24% and 26% of the variation in MAOM and POM stocks, respectively, highlighting a strong genetic influence on SOC dynamics.
Root Chemistry Over Biomass or Recalcitrance
Contrary to expectations, SOC accumulation was not linked to aboveground productivity or root biomass recalcitrance (C:N ratio, lignin). Instead, MAOM-C stocks were strongly associated with root elemental content — particularly a positive relationship with root aluminum (Al) and negative relationships with boron (B) and magnesium (Mg).
Heritable Traits with Biogeochemical Implications
Root elemental traits showed high heritability (57–78%) and did not simply reflect soil chemistry, suggesting a strong genetic basis. Divergence in surface SOC stocks among genotypes ranged from 1.2 to 4.3 t C/ha/year, underscoring the potential for selecting or engineering genotypes with favorable belowground traits.
Implications for Climate-Smart Breeding
These findings support the use of long-term common gardens to uncover plant trait–SOC relationships and highlight root elemental composition as a novel and actionable target for breeding programs aimed at enhancing soil carbon sequestration in agroecosystems.
Schematic of poplar trial and soil sampling, illustrating the location of soil core and fine root sampling relative to the rows of poplar trees and the overlap of their root systems, and the types of analysis conducted on each sample. Scales are exaggerated for illustrative purposes (photo by the authors; root clipart from https://www.hiclipart.com/free-transparent-background-png-clipart-dvzrp)
