My research advances the understanding of soil organic carbon (SOC) dynamics, land-use transitions, and soil quality changes in the ecologically sensitive and data-deficient landscapes of Northeast India. By integrating field-based investigations with process-based modelling and machine learning approaches, my work addresses national priorities related to climate change mitigation, land degradation neutrality (LDN), and sustainable land management. I also generated comprehensive assessments of SOC stocks, dynamics, and sequestration potential across diverse land-use systems, including shifting cultivation fallows, natural forests, tea and rubber plantations, and emerging agroforestry systems, filling key knowledge gaps in a region experiencing rapid land-use change. My findings demonstrate that intensification of shifting cultivation and forest conversion result in significant SOC losses, while agroforestry and perennial systems offer strong carbon-retention potential. By establishing region-specific SOC baselines, my work contributes towards national carbon accounting and supports India’s commitments under the Paris Agreement and the UNCCD’s LDN framework.