Fine Roots Carbon Mineralization and Soil Carbon Stabilization Under Major Tree Species of the Semi-arid Region of India

Abstract

Below ground biomass is a major determinant of soil carbon (C) storage in semi - arid ecosystem. An extended laboratory incubation study for a period of 323 days was carried out to ascertain the decomposition kinetics of fine roots of major trees (Jatropha curcas, Leucaena leucocephala, Acacia nilotica, Azadirachta indica and Prosopis juliflora) and a grass species (Cenchrus ciliaris) in the semi - arid region of India with the hypothesis that species with a slower decomposition rate will increase stability of soil organic carbon and will have higher potential to rehabilitate degraded sites in terms of soil quality. The results were confirmed by analyzing biochemically stabilized carbon pool of soils under different species. Decay constant (k) for fine roots carbon ranged from 0.14 to 0.21 year - 1 under different tree species and followed the order; Acacia[Jatropha][Grass - C. ciliaris][ Leucaena][Azadirachta][Prosopis]. Acid nonhydrolysable C (biochemically stabilized C pool) of soil was maximum in P. juliflora (1.84 g kg - 1) followed by Azadirachta (1.79 g kg - 1). Results emanating from the present investigation suggest that fine roots of A. indica have greater carbon stabilization potential than other species of the region.