Belowground Carbon Storage and Dynamics

This chapter explores the importance and prospects of soil organic carbon (SOC) sequestration for addressing the present day challenge of food and nutritional security and mitigation as well as adaptation to global climate change scenario. Soil organic matter (SOM) is dynamic and vital to soil fertility. Long-term storage of SOC through sequestration in soil has strategic importance in mitigating climate change and improving soil quality. Therefore, an accurate estimation of SOC stocks is necessary which strongly depends on baseline SOC values and involves the quantification of (a) organic carbon concentration of the given soil depth and (b) soil bulk density. Such measurement should be done on equivalent mass basis to avoid imprecision due to presence of residues or changes in bulk density by tillage. The main mechanisms behind SOM stabilization are chemical stabilization, physical protection, and biochemical stabilization. All these processes function by protecting the SOM from microbial decomposition and eventually reducing its decomposition rate in soils. Soil organic carbon sequestration depends on adoption of management practices that increase the amount of carbon stored in soil. The strategies suggested here for SOC sequestration especially in Indian context are integrated nutrient management, conservation agriculture, agroforestry, crop diversification, prevention of soil erosion, and restoration of degraded lands. These C sequestering practices act by increasing the rate of input of organic matter to soils and/or by reducing the turnover rates of SOC stocks already present in the soil. The benefits of SOC sequestration are immense; however, challenges are being encountered which needs to be taken care of.