Relationships between three measures of organic matter or carbon in soils of eucalypt plantations in Tasmania

Organic carbon or organic matter in acidic Tasmanian soils supporting eucalypt plantations was measured by dry combustion using a LECO CHIN-1000 Analyzer (C-T), wet oxidation by the Walkley-Black method (C-W&B), and loss-on-ignition (LOI at 375 degrees C). C-T and C-W&B were highly correlated in 119 surface and subsoil samples, and on average, C-W&B provided near complete recovery of C-T (97%). Although LOI may have released some structural water from the fine-textured soils, and apart from granite-derived soils which need further study, strong regressions were found between LOI and both C-W&B and C-T which were specific for either basalt or non-basalt soils. Within the non-basalt soils, parent material had little effect on these relationships, although there were large differences in C concentrations of surface soils between soils of different parent materials. The relationships of C-W&B and C-T to LOI in the basalt soils were significantly different from those in the non-basalt soils.