Environmental costs and benefits of growingMiscanthusfor bioenergy in the UK.
Planting the perennial biomass cropMiscanthusin the UK could offset 2-13 Mt oil eq. yr-1, contributing up to 10% of current energy use. Policymakers need assurance that upscalingMiscanthusproduction can be performed sustainably without negatively impacting essential food production or the wider environment. This study reviews a large body ofMiscanthusrelevant literature into concise summary statements. PerennialMiscanthushas energy output/input ratios 10 times higher (47.3 ± 2.2) than annual crops used for energy (4.7 ± 0.2 to 5.5 ± 0.2), and the total carbon cost of energy production (1.12 g CO2-C eq. MJ-1) is 20-30 times lower than fossil fuels. Planting on former arable land generally increases soil organic carbon (SOC) withMiscanthussequestering 0.7-2.2 Mg C4-C ha-1yr-1. Cultivation on grassland can cause a disturbance loss of SOC which is likely to be recovered during the lifetime of the crop and is potentially mitigated by fossil fuel offset. N2O emissions can be five times lower under unfertilizedMiscanthusthan annual crops and up to 100 times lower than intensive pasture. Nitrogen fertilizer is generally unnecessary except in low fertility soils. Herbicide is essential during the establishment years after which natural weed suppression by shading is sufficient. Pesticides are unnecessary. Water-use efficiency is high (e.g. 5.5-9.2 g aerial DM (kg H2O)-1, but high biomass productivity means increased water demand compared to cereal crops. The perennial nature and belowground biomass improves soil structure, increases water-holding capacity (up by 100-150 mm), and reduces run-off and erosion. Overwinter ripening increases landscape structural resources for wildlife. Reduced management intensity promotes earthworm diversity and abundance although poor litter palatability may reduce individual biomass. Chemical leaching into field boundaries is lower than comparable agriculture, improving soil and water habitat quality.
Institute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth Wales SY23 3EQ UK.
Jon P
JP
McCalmont
Institute of Biological and Environmental Science University of Aberdeen 24 St Machar Drive Aberdeen AB24 3UU UK.
Astley
A
Hastings
Centre for Ecology & Hydrology Lancaster Environment Centre Library Avenue, Bailrigg Lancaster LA1 4AP UK.
Niall P
NP
McNamara
Rothamsted Research West Common Harpenden, Hertfordshire AL5 2JQ UK.
Goetz M
GM
Richter
Institute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth Wales SY23 3EQ UK.
Paul
P
Robson
Institute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth Wales SY23 3EQ UK.
Iain S
IS
Donnison
Institute of Biological, Environmental and Rural Sciences (IBERS) Aberystwyth University Gogerddan, Aberystwyth Wales SY23 3EQ UK.
John
J
Clifton-Brown
GHG; Miscanthus; biodiversity; bioenergy; crop modelling; energy crops; land‐use change; perennial grasses; plant ecophysiology; renewable energy