Carbon sequestration in red and black soils of semi-arid tropical part of India: I. Influence of morphological properties.

Abstract

Colour, roots, coarse fragments, nodules, effervescence, and slickensides of red and black soils from different bioclimatic systems are described in relation to their organic and inorganic carbon content. Soils under high management (HM) are darker in colour and contain more soil organic carbon (SOC) than those under low management (LM). Higher concentration of roots in soils corresponds with low content of CaCO3 as manifested by dilute HCl in the field. Black soils` under HM show slickensides at lower depth. With the decrease in mean annual rainfall (MAR), the depth of occurrence of slickensides appear at 60 cm in sub-humid (moist) to 30 cm in semi-arid (dry) bioclimate. Management interventions including irrigation in drier tracts push slickensides further down the depth. The formation of sodic Vertisols (Sodic Haplusterts) indicates poor organic carbon accumulation but a very high inorganic carbon sequestration in soils of the relatively dry bioclimatic system. Morphological properties used for grouping soils as per Soil Taxonomy thus can indicate the level of carbon sequestration in soils.