Abstract
The relationships between the vertical distribution of charred plants and the humus composition or the carbon storage in the soil profile of a cumulative Andisol were investigated using 44 soil samples collected from surface and buried horizons. (1) The fraction of less than specific gravity 1.6g cm^<-3>, which was isolated after HCl-HF treatment of the soil samples, was mainly composed of charred plants. (2) The proportion of the amounts of charred plants (CO) to the amount of total organic matter (TO) ranged from 5.15 to 12.4% in 15 soil samples. (3) The vertical distribution pattern of the CO was similar to that of the TO, the amount of humic acid or the amount of fulvic acid. However, their changes were not constantly related to the elapse of soil age. (4) The CO was highly correlated with the sum of the amounts of NaOH-extractable humic acid (a_1) and fulvic acid (b_1) and the amounts of Na_4P_2O_7-extractable humic acid (a_2) and fulvic acid (b_2), the a_1+a_2, the b_1+b_2, the a_1+b_1, the a_1 and the b_1 (r≧0.860). (5) It was assumed that in the cumulative Andisol studied, charred plants contributed to the formation of Type A humic and fulvic acids as well as the carbon storage.
