Accumulation of Soil Carbon Over 12,000 Years in Three Miscanthus Sinensis Grasslands in Japan.

Miscanthus spp. is considered a promising feedstock for the production of cellulosic ethanol and may soon see a dramatic increase in area planted. Research into the effects of Miscanthus on soil edaphic resources is limited to study plots less than 20 years old. To estimate the long term effect of Miscanthus on accumulation of soil carbon (C) stock in its home range, we measured total C at 10 cm intervals to 1.2 m depth along a catena sequence in three grasslands at varied latitudes in Japan. Soil carbon stock (Mg/ha) was estimated by combustion and age was estimated from radiocarbon dating—providing the net soil C accumulation rate (Mg C/ha/year) to 120 cm. Miscanthus contribution to soil C was estimated by C-4 discrimination. Three Miscanthus grasslands were examined in Japan, Kawatabi (KAW), Soni Kogen (SON), and Mt. Aso (ASO), ranging in Latitude from 32° to 38° N. To 1.2 m depth, total soil C (Mg C^.ha^-1): in the profile ranged: KAW (379-640), SON (249-483), and ASO (371-406). Catena position was only a significant factor at KAW, where the tow slope soil C accumulation exceeded the peak. Soil C stock in the grasslands, derived mainly from Miscanthus C, accumulated between 9,000 and 12,000 years before present.