Mechanisms and Processes of Soil Organic Carbon Sequestration in Ethiopia: A Review

Photosynthesis, litter decomposition, and root exudation are key processes contributing to organic carbon sequestration in ecosystems. Soil organic carbon (SOC) is a heterogeneous mixture of organic components, including microbial biomass, plant and animal residues, simple sugars, complex organic compounds, and carbohydrates. Globally, soils contain an estimated 1,550 Pg of organic carbon. However, historical land conversion for agriculture has caused substantial carbon losses, with approximately 78 Pg lost mainly through erosion and mineralization. In Ethiopia, SOC loss is similarly attributed to soil erosion and land use change, with estimates ranging from 15 to 1,000 kg ha<sup>-1</sup> yr<sup>-1</sup>. SOC sequestration occurs through various mechanisms, including carbon inputs from plant litter, crop residues, and rhizodeposition. The stabilization of SOC plays a vital role in the long-term storage and protection of carbon in soils. Physical protection involves strong chemical bonding between SOC and the soil’s mineral matrix and the physical inaccessibility of SOC to decomposers. Biological protection involves the encapsulation of SOC within soil aggregates and hydrophobic domains of soil organic matter. Overall, SOC storage is influenced by complex interactions among soil, plant systems, and management practices. Effective soil management strategies can significantly enhance SOC sequestration in croplands.