JEAS-Blog (2025.10.23)
Soil Organic Carbon (OC) and Iron (Fe) Oxides at The Soil Micro-Scale Interfaces
Soil Organic Carbon
Organic Carbon (OC) is a fundamental component of soil health, stored within organic matter. It enhances soil structure by forming stable aggregates, which improve porosity, water retention, and root growth. As a substrate for microbes, it drives nutrient cycling, releasing nitrogen and phosphorus to maintain fertility. Crucially, soil OC is a major global carbon sink, mitigating climate change.
Iron Oxides in the Soil
Iron oxides are highly reactive soil minerals that govern key soil processes. They provide extensive surfaces for the adsorption and transformation of nutrients and pollutants. A critical function is their direct binding to organic carbon, forming stable organo-mineral complexes that protect OC from microbial decomposition. This action, particularly by poorly crystalline Fe oxides, is vital for long-term carbon storage and enhances soil aggregate stability.
Synergistic Role of Organic Carbon and Iron Oxides The interaction between OC and Fe oxides is a primary mechanism for soil carbon stabilization. Fe oxides act as a mineral shield, binding OC and encapsulating it within soil aggregates. This physical protection significantly reduces the decomposition rate of OC, leading to: 1. Enhanced soil carbon sequestration. 2. Improved soil structure and fertility. 3. Greater ecosystem resilience. highly reactive
Interactions Between Organic Carbon and Iron OxidesMineral Architecture: The soil micro-scale is a complex architecture composed of iron oxide minerals existing as discrete particles, cemented aggregates, and coatings on pore walls. This heterogeneous structure creates a vast surface area with diverse chemical environments that dictate the fate of OC.
Organic Matter Transformation and Interaction Pathways: Before sequestration, complex organic matter (Lignin, polysaccharides) often undergoes partial oxidative depolymerization. The resulting smaller molecules and biomolecules then access mineral surfaces through several key mechanisms:
Reference Robinson KA, Saldanha IJ, Mckoy NA. 2011. Development of a framework to identify research gaps from systematic reviews. J. Clin. Epidemiol. 64(12):1325-30.
Journal of Environmental and Agricultural Sciences (JEAS)