Soil organic carbon fractions under different land use systems of Jorhat district

The present study was conducted using soil profiles of Jorhat district under different land use systems (LUS) i.e. Bamboo field, tea plantation and rainfed rice. The total soil organic carbon content at 0-15 cm depth varied from 7.86 to 8.43 g kg-1, wherein rainfed rice land use system recorded significantly higher total organic carbon (TOC) than tea plantation but at par with that of bamboo field. However, at 15-30, 30-60 and 60-100 cm soil depths bamboo field recorded significantly higher over other land use systems. Among these LUS, rainfed rice showed significantly higher very labile carbon (CVL) in soil than tea plantation and bamboo field at 0-15 cm depth whereas in 15-30 cm depth CVL in tea plantation was found to be significantly higher than bamboo field and rainfed rice. However, Bamboo field and tea plantation had CVL significantly higher than rainfed rice under 30-60 and 60-100 cm depths, respectively. In all the depths, labile carbon pool (CL) was significantly higher in bamboo field ranging from 1.01 to 1.67 g kg-1 whereas under bamboo field, less labile carbon (CLL) pool 0-15, 15-30 and 30-60 cm depths was significantly higher than tea plantation and rainfed rice soils. However, the recalcitrant carbon (CR) pool did not vary significantly among different LUS. Soil organic carbon stock in soil at 0-15 cm depth was found to be significantly higher in rainfed rice soil than tea plantation and bamboo field whereas in the remaining depths the SOC stock was significantly higher under bamboo field. Moreover, the interaction between LUS and depths varied significantly. Among different fractions (CL, CLL, CVL and CR fractions), CR fraction had the smallest variation among land uses, which indicate that the non-labile fraction was less sensitive to land use systems.