Abstract: Ameliorating effect of biochar in varying concentrations (i.e., 0, 8, 16, 32 and 64 t hm^-2) on acidity of tea garden soils were studied in field trials. The results showed that, as compared with CK (no added biochar), the soil pH increased by 0.19-1.72, the soil exchangeable acid decreased by 0.79-3.96 cmol·kg^-1, the soil base saturation increased by 20.98-173.67%, and the soil cation exchange capacity (CEC) increased by 0.80-2.46 cmol·kg^-1 on the 0-20 cm layer of the soils. On the other hand, in the 20-40 cm layer of the soils, the pH of the treatment samples increased by 0.05-0.61, the soil exchangeable acid decreased by 0.20-2.14 cmol·kg^-1,the soil base saturation increased by 27.72-56.51%, and the soil CEC increased by 0.57-1.12 cmol·kg^-1. It appeared that the soil ameliorating effect increased with increasing biochar addition. The increase was particularly significant in the 0-20 cm than the 20-40 cm layer of the soils. The yield of the fresh tea leaves was changed 6.61%, 5.62%, -0.11% and -0.77% by the addition of biochar at the rates of 8, 16, 32 and 64 t·hm^-2, respectively. However, no significant differences (P>0.05) on tea yields between the treatments and control was found.

Key words: biochar, soil acidification, soil, soil amelioration, tea garden