Qualitative Assessment of Soil Organic Carbon Pools using UV-Vis Spectroscopy

Soil acts as the niche of Carbon (C). Soil carbon sequestration is of paramount importance for sustaining soil health as well as mitigating global warming. Studies on soil organic C content of both surface as well as deep subsoil are very important.  Besides, studies on C in rice soil, as well as non-rice upland soil of tropical India, are also of principal importance. With this background, the present experiment was undertaken to recognize qualitative characteristics of water-soluble soil C in rice soil and non-rice soil along depth using UV-Vis spectroscopy.  Soil sampling was done from representative rice and non-rice soil ecologies in West Bengal from 0-20 cm, 100-120 cm and 120-140 cm soil depths. Quality and stability of C can be estimated by studying the nature of absorbance of water-soluble C in UV-visible range.  Results indicated a higher absorbance of C in the subsurface than that of surface soil. Similarly, higher absorbance of C was recorded in soil collected from rice ecology compared to non-rice ecology. Irrespective of soil depth, it was noted that there was more humified as well as aromatic C in rice ecologies than that in non-rice ecologies. Thus soil of lower depth as well as rice ecologies acts as a better niche for sequestrating C in soil.