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MISCANTHUS  genetic experiment © Aline Waquet

Miscanthus, a very promising plant...

Environmental impacts of Miscanthus

Researchers are carrying out assessments of the environmental impacts of miscanthus crops, in terms of energy and greenhouse gas emissions. The balances are favourable for both criteria.

By Pascale Mollier - Maryse Brancourt-Hulmel - Hubert Boizard - Fabien Ferchaud, translated by Inge Laino
Updated on 04/22/2013
Published on 02/15/2013

Biomass and Environment experiment at INRA's Estrées-Mons site.. © INRA, PAILLARD Gérard
Biomass and Environment experiment at INRA's Estrées-Mons site. © INRA, PAILLARD Gérard

At INRA’s Estrées-Mons site (cf part 2 of this report), researchers are carrying out assessments on several aspects of miscanthus crops including the quantity and quality of dry material generated at different growth stages, nitrogen content in soil and plants, patterns and changes in organic matter of each harvest, greenhouse gas emissions, and water consumption of crops. These assessments are used to establish energy balances and the environmental impact of miscanthus crops.

Savings on nitrogen fertiliser and energy

Miscanthus crops are low-maintenance and require very little in the way of nitrogen fertilisers, which is a big advantage for its energy balance (the production of nitrogen fertilisers being energy-intensive). If the crop is harvested late, nitrogen is recycled very efficiently:  it is stored in the rhizomes at the end of the growing cycle, then retrieved by the plant in the spring to resume growth (Loïc Strullu 2011 thesis, Enerbio project). In this case, there is little need for nitrogen fertilisers: approximately 30 kg/ha/year can be enough to make up for nitrogen losses that occur at harvesting. Nitrogen losses through leaching (nitrates carried away by water as it percolates through the soil) are very limited, except during planting.

A small greenhouse gas footprint

Device for measuring N2O emissions in a Miscanthus x giganteus crop.. © inra
Device for measuring N2O emissions in a Miscanthus x giganteus crop. © inra

In terms of greenhouse gases (GHG), perennial miscanthus crops score very well. Thanks to minimal requirements in terms of nitrogen fertilisers, nitrous oxide (N2O) emissions from the ground are kept at bay. Studies carried out in the field have allowed researchers to better evaluate emissions in relation to harvesting practices: they confirm that losses are kept in check when fertilisation is kept to a minimum.

References

Strullu L., Cadoux S., Preudhomme M., Jeuffroy M.H., Beaudoin N. 2010. Biomass production and nitrogen accumulation and remobilisation by Miscanthus x giganteus as influenced by nitrogen stocks in belowground organs. Field Crops Research,121, 381-391.

Cadoux S., Ferchaud F., Demay C., Boizard H., Machet J-M., Fourdinier E., Preudhomme M., Chabert B., Gosse G., Mary B. 2013. Implications of productivity and nutrient requirements of greenhouse gas balance of annual and perennial bioenergy crops. Global Change Biology Bioenergy, forthcoming.