Soil redox potential as predictor of heterotrophic respiration of an oil palm plantation-peatland in Riau

Abstract

Soil respiration consists of autotrophic and heterotrophic respiration, in which in a peatland the latter is equivalent to the decomposition of peat material. This study aimed to develop a model of soil redox potential (Eh) as a pedictor of heterotrophic respiration of an oil palm plantation cultivated in tropical peatland. Soil respiration was measured using closed chamber method at close-to-tree (2 m distance from the tree) and far-from-tree (4.5 m from the tree) plots, while for heterotrophic one was at root-cut (4.5m from the tree) plots prepared by root-trenching up to 80 cm depth with 8 months’ incubation. Soil respiration of the study site was 40.81 ton CO2 ha-1.y-1, 50.53% of which was contributed by respiration from the heterotrophic components (RHC). The latter correlated positively with soil Eh at pH 7 measured at-30 and-90 cm depth (Eh7~30 and Eh7~90), and negatively with soil water level. Significant values of simple linear correlation coefficients (r= 0.838 and 0.866, each with n= 12) with RHC were shown by Eh7~30 and Eh7~90, respectively. Therefore, these factors could be suggested as predictors for RHC by equation: RHC (ton CO2 ha-1.y-1) = 18.2 + 0.029 Eh7~30 + 0.037 Eh7~90 (Eh in mV).