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

Christensen, Bent T., Lærke, Poul Erik, Jørgensen, Uffe, Kandel, Tanka P., Thomsen, Ingrid K.
Canadian journal of soil science 2016 v.96 no.4 pp. 354-360
Miscanthus, carbon, carbon sequestration, carbon sinks, energy crops, greenhouse gas emissions, rhizomes, roots, sandy soils, stable isotopes, Denmark
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.