Miscanthus for a Sustainable Development: How Much Carbon Is Captured in the Soil?

Soils are an important sink for the carbon storage in the form of soil organic carbon and reduction of CO2 in the atmosphere. But, the beneficial effects and applicability of carbon sequestration by perennial grasses, still need to be demonstrated. Historical and unpublished data of long-term Miscanthus plantations in Caparica, Portugal, were analysed in order to establish its influence on soil organic matter. Miscanthus plantations were established in clay soil and parallel to Miscanthus plantations, there were parcels of land without the crop, for comparison. Data on belowground biomass production and litter production along the growing cycle and along several years were examined because of their potential importance to soil C sequestration. Soil organic matter were also monitored along the long-term plantations. Results show that the presence of Miscanthus in the soil contributed to an increment of organic matter by comparison with soils without the crop, although this increment is not statistically significant. Recycled carbon to soil from litter of Miscanthus represents ca 3.1-3.9 Mg.ha-1.year-1. Carbon sequestration by the root and rhizome system is considerable, representing ca 12.5-13.5 Mg.ha-1, over the life time of the system. But this soil-rhizome accumulation can become prejudicial if land use will be changed, by release of the stored carbon.