Estimation of soil organic carbon turnover using natural 13c abundance in asian tropics: A case study in the philippines

Abstract

The organic carbon (C) content and natural 13C abundance (Σ13C) of two series of forest and sugarcane soils from Central Luzon and Negros Island in the Philippines were analyzed to determine the origin and turnover of soil organic C in the Asian tropics. The organic C contents and Σ13C values were investigated after a long period (years) of sugarcane cultivation following forest clearing. Conversion of forest areas to field for sugarcane cultivation had been associated with a rapid decrease of the soil organic C content and increase of the soil Σ13C values. The easily mineralisable compartment accounted for 95 and 98.5% of forest- derived C and the half-lives were 1.2 and 1.8 years in Central Luzon and on Negros Island, respectively. On the other hand, sugarcane-derived C accumulation accounted for 25 and 22% of the soil organic C content of natural forests. © 2004 Taylor & Francis Group, LLC.