Comparative Studies on Effect of Conventional Practices on Soil Quality Parameters and Carbon Stock in Common Land Uses in Namthang Block, South Sikkim

Landuse is the prime management intervention that results to significant changes in the physicochemical properties. Two (2) Land use systems (Maize- broadbean and ginger) were selected for study. A total of sixty (60) soil samples were collected from five (5) different villages of Namthang Block from two different depths viz. 0-0.20m and 0.20-0.40m. The samples were analysed for the soil physicochemical properties, soil carbon, carbon stock, fertility status and biological properties. It was observed that the soils were moderately acidic to slightly acidic in reaction, high in organic carbon. Bulk density and particle density ranged from 1.02-1.30 g cm-3 and 2.45-2.69 g cm-3 at the surface soil in the maize-broadbean LUS and the densities increased with depth. The soils were found to be medium in N, P, K and S. The exchangeable calcium and magnesium ranged from 0.54-1.18 [Cmol (P+) kg-1] and 0.51-1.06 [Cmol (P+) kg-1] at the surface soil in the maize-broadbean LUS. The Soil microbial biomass carbon and dehydrogenase activity was found to be decreasing with increasing soil depth. The organic carbon stock ranged from 24.51-32.00 (Mg ha-1) at the surface soil in the maize-broadbean LUS and found to be decreasing with increasing soil depth. Substantial amount of SOC stock indicated fairly healthy soil of Namthang block. Maize-broadbean LUS found to be superior over ginger LUS owing to enhanced soil fertility as well as biological parameters.