Quantifying Carbon Sequestration Potential of Soils in An Agro-Ecological Region Scale

Soil potential to store organic carbon was assessed in the hot sub-humid dry Agro-Ecological Region (AER) of the Indo-Gangetic Plains under Recent alluvium of southern Bihar, India. The study was carried out in four prevailing cropping systems, viz. Rice–Wheat– Fallow (R–W–F), Pearl millet–Wheat–Fallow (P–W– F), pigeon pea (monoculture) and vegetable cultivation. Two different recovery factors were used to estimate Total Organic Carbon (TOC), which yielded similar results. The Soil Organic Carbon (SOC) was found highest in pigeon pea-grown soils (69.2 tonnes ha^–1) followed by R–W–F (56.2 tonnes ha^–1) and vegetable cultivation (55.8 tonnes ha^–1). The lowest SOC stock was found with P–W–F (19.2 tonnes ha^–1). The differences in SOC stock between pigeon pea and that of rice–wheat, vegetables and pearl millet–wheat are 13.0, 13.4 and 50.0 t ha^–1 respectively, that are the quantity of organic carbon can be sequestered further in these three land uses from 47.71, 49.12 and 183.50 tonnes of carbon dioxide from the atmosphere respectively. Highly significant positive correlation of soil qualities parameters such as available nitrogen (r² = 0.25), copper (r² = 0.45), zinc (r² = 0.31) and dehydrogenase activity (r² = 0.44) was found with SOC stock under the hot, sub-humid, dry, AER of southern Bihar. Similar assessment can be done in any AER and the potential of soils can be identified to increase carbon sequestration from the atmosphere.