Soil Organic Carbon Pools in Rice Growing Inceptisols of Northeast India

Abstract

ABSTRACT Estimation of soil organic carbon (SOC) stock and its pools is important for understanding C budgeting and ecosystems services of any land use. The present study was conducted to quantify SOC stock and its pools of different oxidizability (very labile, labile, less labile and non-labile C), microbial biomass C and mineralizable C at different depths (0–0.15, 0.15–0.30 and 0.30–0.50 m) of selected 26 rice growing Inceptisols located in the subtropical Manipur valley, India. Results of this study showed that organic C stock in 0–0.50 m depth of the rice growing Inceptisols varied from 55.7 to 133.5 Mg ha−1 and there was a decrease in SOC stock along depth. The rice growing Inceptisols under subtropical climate of northeast India are characterized by cooler climatic conditions and soil acidity, which are favorable for SOC accumulation. The study also showed that more than two-third (72.0%) of SOC is present in active pools with rapid turnover. Therefore, much of the SOC in these soils is very susceptible to changes in management practices such as increased tillage intensity, inappropriate cropping without legume and inadequate fertilization and in weather conditions such as increased temperature.