The results of this study confirmed the effectiveness of wood
biochar in improving the physical and chemical properties of soil
that is highly weathered. The results indicated that the improvements
in soil characteristics varied with variations in the amount of biochar
added to the soil. Incubation results indicated that soil pH, CEC, and
BS increased significantly after the addition of biochar, particularly
at the application rate of 5%. The high liming potential of the biochar
(pH N9.0) raised the pH of the highly weathered soil. Our results further
showed that pH increased significantly with increasing application
rates of biochar, reflecting the fact that the liming potential
increased with increasing application rates of biochar. This correlated
with the results of Yuan and Xu (2011), who indicated a significantly
positive linear correlation between biochar-treated soil pH and
biochar pH (r2 = 0.46, p b 0.05). In this study, the biochar-treated
soil did not exhibit a significant increase in SOC levels (Fig. 2b),
even though the biochar used had a high TC content (78.3%) and C/N
ratio (121). This could be attributed to the lowerWalkley–Black C content
(1.82%) in the biochar (Table 1).