Rice husk ash and rice husk biochar had a high pH (Table 1); therefore, it is reasonable that the soil treated with rice
husk biochar and rice husk ash also had a high pH. This result indicated that rice husk biochar could be used as a
substitution for lime materials to increase the pH of acidic soils. The increase in CEC of the soil with organic soil
amendments would probably be due to the negative charge arising from the carboxyl groups of the organic matter. The
increase in CEC and soil pH with the addition of organic matter has been shown elsewhere (see Bot and Benites, 2005).
Biochar has a high CEC (see Table 1), and with its high recalcitrance (Glaser et al., 2002), it is reasonable that soil
applied with biochar had the highest CEC. An increase in soil CEC with the application of biochar has also been shown
by Chan et al. (2007)