Miscanthus

IMG_7841Miscanthus is a woody rhizomatous C4 grass species which originated in SE Asia and was initially imported to Europe as an ornamental plant. It is a perennial plant with an estimated productive life of around 16 years. It grows to 3-4m in height and the stems and leaves can be harvested annually. It utilises the C4 photosynthetic pathway in contrast to the C3 pathway utilised by standard arable crops in Northern Europe (such as wheat, oilseed rape potatoes). As such its shows a higher irradiation conversion efficiency than C3 plants and is also more efficient in its use of nitrogen and water. It is affected by low temperatures, but is better adapted to temperate climates than most other C4 crops (such as maize).

Establishing a miscanthus plantation costs around £2500-£3000 per hectare although it is also eligible for a 50% establishment grant through the Energy Crops Scheme. As a general rule it is considered a viable option for farmland south of a line drawn between the Severn and the Wash. However, extensive plantings have been established in Yorkshire to fuel the Drax power station.

Miscanthus is grown as a monoculture of one variety of M x giganteus although there is a breeding programme underway at the Institute of Biological, Environmental and Rural Sciences at Aberystwyth University to increase the genetic base of the crop. There are currently no significant economic pests and diseases.

Pros Cons
Harvested annually Monoculture
Uses conventional agricultural machinery Only one or two varieties in cultivation – no significant disease or pest problems – yet!
Reasonable contractor rates as outside typical forage harvester season Challenging fuel – typically more hands on due to higher ash and mineral content.
Limited pests and disease Higher establishment costs
Annual harvests provide better cash flow Generally lower returns than SRC due to annual harvesting
Lots of alternative markets e.g. biocomposites, horse bedding Does not respond to N fertilizer
Low inputs required Low density fuel so transport is typically more expensive
Uniform crop Requires covered barn for storage of bales
Typically higher yields than SRC More limited boiler selection
Lower moisture content when harvested