Storage of Miscanthus-derived carbon in rhizomes, roots, and soil

Abstract

Compared with annual crops, dedicated perennial bioenergy crops are ascribed additional benefits in terms of reduced greenhouse gas emissions; these benefits include increased carbon (C) storage in soil. We measured Miscanthus-derived C in rhizomes, roots, and 0-100 cm soil beneath three 16-yr-old stands established on sandy soils at two experimental sites in Denmark. Miscanthus C in soil was estimated from changes in the natural abundance of 13C. In the 0-20 cm depth, soil C derived from Miscanthus made up to 15-18% of the soil total C. In the 20-50 cm and 50-100 cm depth, Miscanthus C accounted for less than 7% and 5% of the soil total C, respectively. After 16 yr, the total quantity of Miscanthus C in 0-20 cm ranged from 11.9 to 18.2 Mg C ha-1, of which 23-34% was in rhizomes and roots, substantiating their crucial contribution to soil C storage. Future studies should prioritize the seasonal and annual dynamics of C stored in rhizomes and roots, and the fate of these C pools following termination of Miscanthus stands.