Role of Aggregates and Clay Minerals in Carbon Mitigation of Sodic Soil

The aim of this study was to analyze soil aggregate carbon storage and clay mineralogy of sodic soils located in the Panipat district of Haryana, India (Panipat, Samalkha and Israna blocks; 29.39°N, 76.97°E; average elevation 219 m / 718 ft). The soils were strongly alkaline, with pH values ranging from 8.86 to 9.11. The climate of the region is semi-arid and monsoonic. Soil analysis showed that microaggregates (250–53 µm and <53 µm) constituted the largest fraction of soil aggregates and played a dominant role in protecting soil organic carbon (SOC). The total carbon content was higher in microaggregates (250–53 µm) compared to the silt- and clay-associated fractions (<53 µm). Soil aggregate carbon biomass exhibited a significant relationship with SOC across different soil depths. Clay mineralogical analysis revealed that montmorillonite, chlorite, illite, kaolinite, and vermiculite were the dominant clay minerals present in the soils. The findings suggest that conservation of native wild vegetation on salt-affected soils can enhance carbon sequestration by improving soil structure and increasing SOC storage within aggregate fractions. In sodic soils, aggregates and clay minerals are the twin pillars of carbon stabilization. While sodicity disrupts both, reclamation practices that restore aggregation and clay reactivity can transform degraded soils into effective carbon sinks. Harnessing this mechanism not only improves soil fertility and productivity but also contributes significantly to climate change mitigation strategies.