Energy Crop Options

Energy crop growing is a long term investment for farmers and land owners and it is crucial that you make the right choice for you. There are a variety of options available and you should base your choice on the land available and the requirements of the end user. Energy crop options include:

• Short rotation coppice
• Miscanthus
• Reed Canary Grass
• Switch grass
• Short rotation forestry
• Broadleaved coppice

Short Rotation Coppice (SRC)

SRC consists primarily of densely planted, high yielding varieties of willow, and occasionally poplar, harvested on a two to five year cycle, although most commonly every three years. The rootstock or stool is left in the ground and after each harvest new shoots emerge, as in traditional coppice. It is currently expected that an SRC plantation should be viable for 30 years before it needs replanting. Full best practice guidelines can be found in the DEFRA publication ‘Growing Short Rotation Coppice’.

SRC costs around £2000 per hectare to establish but is eligible for a 40% planting grant through the Energy Crops Scheme. It can be grown on marginal and reclaimed land although a reduction in yield should be expected in these circumstances. Harvesting takes place during the winter and therefore provides employment opportunities for agricultural workers at a quiet time of year. However, as it is a perennial crop with reduced requirements for pesticide application or other annual arable operations it has a lower labour requirements overall compared to other arable crops.

Miscanthus

Miscanthus 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 15 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 £2300 per hectare although it is also eligible for a 40% 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.

Reed Canary Grass

Reed canary grass (Phalaris spp.) is a native perennial C3 grass that is propagated by seed or rhizome. It grows to a maximum height of 2m and produces a maximum yield of 12.5odt/ha/yr (48.8 odt/ha over six years). It is a good short–term energy crop, especially as this it has much lower establishment costs (around £341/ha) than Miscanthus. There are however, various problems associated with growing reed canary grass:

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  • It is susceptible to various pests.
  • It is prone to lodging.
  • It does not fully senesce in winter, making harvest difficult.
  • It requires too much Nitrogen for the yield achieved.

This crop is not eligible for an establishment grant because it is very economical to plant and therefore doesn’t justify support.

Switchgrass

Switchgrass (Panicum spp.) is a perennial C4 grass from North America, which is propagated by seeds. It grows up to 2.5m in height and produces a maximum yield of 14 odt/ha/yr (51.7odt/ha over six years). Like Reed Canary Grass it has low input costs (around £357/ha) and the gross margin should increase as the crop becomes more established. The crop has the following drawbacks:

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  • Some varieties are prone to lodging.
  • It does not respond to Nitrogen fertilizer.

This crop is not eligible for an establishment grant because it is very economical to plant and therefore doesn’t justify support.

Short rotation forestry (SRF)

SRF involves planting single stemmed trees over rotations between 8-20 years depending on the species chosen. This practice is similar to conventional forestry and trees are harvested when they reach 10-20cm at breast height (1.3m). The area can then be replanted or allowed to become longer rotation coppice. Fast growing trees with potential for SRF include native trees such as poplar, sycamore, ash, birch and alder and exotic species such as shining gum (Eucalyptus nitens and E. gunnii), and southern beech (Nothofagus spp).

SRF has great potential as single stemmed trees can be planted in areas unsuitable for SRC and miscanthus. All operations are performed using conventional forestry equipment and the yields and quality of woodfuel produced should be superior. However, SRF has until now received little research and development and as a result there is a great deal of uncertainty about the performance of individual species, plantation design and the optimum point for harvest. As a result there is little guidance available for interested farmers.

Currently, SRF is not funded under the Energy Crops Scheme. It is possibility that funding might be sourced through the English Woodland Grant Scheme but it is unlikely that an application for establishing new woodland containing a high proportion of exotic species will score highly against the criteria described in the Woodland Creation Grant Scoring Form.

Broadleaved coppice

Broadleaved coppice involves growing native trees such as ash, sycamore, sweet chestnut, alder and hazel. The plantation should be cut back to ground level after 5 years to promote the production of many shoots and then harvested every 10-15 years thereafter. Broadleaved coppice is eligible for a 40% planting grant through the Energy Crops Scheme.

The yields of native species grown as broadleaved coppice are likely to be much less than SRC willow or poplar on the same site. Forestry Commission Guidance suggests that yields might be 50-66% lower than SRC. This is because individual trees are propagated from seeds and so the plantation will follow a normal distribution pattern with some performing better than others.

Broadleaved coppice is probably the most appropriate energy crop for visually sensitive areas. It is also a versatile option being suitable for establishment on grassland areas of low biological interest and poor quality agricultural land (grades 4 and 5).