Long-term Fertilization Boosts Organic Carbon Sequestration in Agricultural Soils

Strategic Insights -

Research published in Land Degradation & Development, a journal from Wiley, has shown that long-term application of nitrogen and phosphorus fertilizers can significantly enhance organic carbon sequestration in agricultural soils. Led by Ying Liu from Northwest A&F University, the study revealed that these fertilizers stimulate soil organic carbon (SOC) accumulation primarily by modulating microbial carbon fixation processes through root exudate composition. This finding offers valuable insights into the microbial mechanisms underlying SOC sequestration in low-fertility farmland.

Key Takeaways:

  • The study, funded by the National Natural Science Foundation of China and the National Key Research & Development Program of China, was conducted on loess hill farmland with 26 years of nitrogen and phosphorus fertilization.
  • The researchers found that applying N and P fertilizers led to notable boosts in soil organic carbon (SOC), reactive organic carbon (KOC), and recalcitrant organic carbon (ROC), with increases of 33%, 30%, and 39% respectively, compared to the control.
  • Mechanistically, N and P fertilization altered root exudate composition, with organic acids comprising over 60% of the total exudates.
  • These changes in exudates promoted the enrichment of C fixation functional genes, particularly aclB and acsA, which are responsible for enhancing C fixation in the soil.
  • The researchers also found a positive link between reactive C fractions and C fixation gene abundance, and a negative association with C degradation genes.

Statistics:

  • 26 years of nitrogen and phosphorus fertilization on loess hill farmland.
  • 33% increase in soil organic carbon (SOC) due to N and P fertilization.
  • 30% increase in reactive organic carbon (KOC) due to N and P fertilization.
  • 39% increase in recalcitrant organic carbon (ROC) due to N and P fertilization.
  • 60% of total exudates composed of organic acids.

Sources:

  • Long-term Nitrogen and Phosphorus Fertilization Promote Organic Carbon Sequestration In Agricultural Soils By Regulating Crop Root Exudates and Carbon Functional Gene Abundance. Land Degradation & Development, 2025.
  • National Natural Science Foundation of China (NSFC)
  • National Key Research & Development Program of China
  • Northwest A&F University
  • Ying Liu, Northwest A&F University, Institute of Soil and Water Conservation, Coll Soil & Water Conservat Sci & Engn, Yangling, Shaanxi, People's Republic of China
  • Chunxiao Wu, Guoliang Wang, Guobin Liu, Furong Wei, and Benshuai Yan, authors of the study.