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Willow short rotation coppice (SRC)
Varieties
Willow (Salix spp.) is planted as rods or cuttings in spring using specialist equipment at a density of 15,000 per hectare.  The willow stools readily develop multiple shoots when coppiced and several varieties have been specifically bred with characteristics well suited for use as energy crops.  Information and advice is available from the Forest Research Yield models for energy coppice of poplar and willow website.
Growth

During the first year it can grow up to 4m in height, and is then cut back to ground level in its first winter to encourage it to grow multiple stems.

The first harvest is in winter, typically three years after cut back, again using specialist equipment, however a cycle of 2 or 4 to 5 years is also common.

In fertile sites growth can be very strong during the first two years after coppicing, giving rapid site capture, reducing thereafter and so a 2 year cutting cycle may be more appropriate.

Yield

Yield is dependent on many factors, including:

  • Site
  • Water availability
  • Weed control
  • Planting density
  • Light
  • Temperature.
Harvesting

Typically the first harvest may be expected to be somewhat lower than subsequent ones, and figures from 7 to 12 oven dried tonnes per hectare per annum can be expected on reasonably good sites.

Harvesting may be as rods (up to 8 m length), billets (5-15 cm lengths) or as direct chip harvesting.  Direct chip harvesting can cause problems for storage with rapid composting (and hence loss of energy content) and mould formation (and attendant health risks) owing to the high moisture content of freshly harvested willow.  This can be less of a problem with billets owing to improved air flow through the pile.

Chipping
Shredding and grinding
Viability
A willow SRC plantation may be expected to be viable for up to 30 years before it becomes necessary to replant and can reach 7-8 m in height at harvest.  The site should be reasonably flat, or with a slope no more than 7% and, to be eligible for the Defra Energy Crops Scheme (ECS) grant, needs to be at least 3 ha, though this need not all be in a single plot.
Energy Crops Scheme
Establishment grants of 50% of eligible costs for planting SRC willow or poplar, miscanthus, or a range of short rotation coppice traditional broadleaf species.

Administered by Natural England. More information on their website: www.naturalengland.org.uk/ourwork/farming/funding/ecs/default.aspx

For further information
Yield models for energy coppice of poplar and willow
Information on many aspects of SRC for growers, researchers and the bio-energy industry (Forest Research)
Growing short rotation coppiceGrowing short rotation coppice
Best practice guidelines for applicants to Defra's Energy Crops Scheme (PDF - 4.1 MB)
New draft: Growing Short Rotation Coppice (advanced draft Autumn 2008)New draft: Growing Short Rotation Coppice (advanced draft Autumn 2008)
An advanced draft of the new Defra guidance on growing short rotation coppice for applicants to the Energy Crops Scheme (PDF - 163 KB)
NNFCC Crop Factsheet: Short Rotation Coppice Willow (SRC)NNFCC Crop Factsheet: Short Rotation Coppice Willow (SRC)
Information from the National Non-Food Crops Centre (NNFCC) on growing, harvesting and storing short rotation coppice willow (SRC) in the UK and its uses as a non-food crop (PDF - 110 kB)

Other short rotation coppice cropsOther short rotation coppice crops

Willow short rotation coppice
Defra energy crops opportunity maps
Including existing energy crops locations.
(N.B. Now on the archived Defra website)