Soil organic carbon (SOC) contents of 562 Taiwan non-calcareous forest soil samples were
determined by the Walkley-Black (WB) method and an elemental analyzer. The data analyzed
by the elemental analyzer were taken as the standard, to obtain the SOC recovery rate by the WB
method in 7 forest types (coniferous forest, coniferous-broadleaf mixed forest, warm temperate
broadleaf forest, coniferous plantation, bamboo/bamboo-broadleaf mixed forest, broadleaf plantation,
and subtropical broadleaf forest) and their soil horizons (A, B, and C), in order to obtain suitable
correction factors. SOC data of the WB method and the elemental analyzer were 0.06~36.4%
and 0.08~44.6%, respectively. Recovery rates ranged 50.4~93.7% with an average of 75.6% for all
samples. There was no significant correlation between SOC concentrations and WB recovery rates.
All forest types had higher recovery rates in the A horizon than the B and C horizons, while no significant
difference was found between the B and C horizons. Although recovery rates significantly
differed among forest types, the correction factors were quite similar. Correction factors of the A
horizon ranged 1.19~1.27, and those of the B and C horizons were 1.29~1.37, while averages were
1.24 and 1.34, respectively. It is suggested that a general value of 1.30 can be used to estimate the
organic carbon content of a wide range of soils; however, for a more-accurate estimate of SOC
contents in Taiwanese forests, the A horizon can use 1.24, and the B and C horizons can use 1.34.