Farm Diversification

Crops are generally grown on a small scale with a high level of inputs appropriate to the crop. 

Widespread knowledge of the agronomy of some of these crops and the availability of suitable approved agrochemicals is limited.  These factors present challenges for individual growers seeking to cultivate such crops. 

Crops may be mown and wilted in the field for a short time to reduce moisture content before being picked up and placed in a steam distillation unit. Yield of essential oil is generally extremely low e.g. a good yield of lemon balm can be 1 litre of essential oil per hectare.  

The less favourable conditions at harvest in Scotland may present even greater challenges for development of many of these crops in this area.

Price of essential oils produced from many essential oil crops is high; lemon balm can attract £2,500 per litre and German chamomile £400/kg, offering good potential gross margins.

The economic potential for many essential oil crops may be limited by less favourable conditions in Scotland. 

• Bog myrtle, however, offers opportunities for northern Britain as it is found in upland areas of the north and is attracting significant interest due to its midge repelling properties.  Considerable work to develop bog myrtle as a crop has been carried out, with the creation of a specialised harvester for upland conditions and steam distillation unit to enable extraction of the essential oil on site.  Preparations from the plant are now marketed under the name ‘sweet gale’.

Essential oils can be extracted from plant material using steam distillation. 

Small scale stills are available for on-farm use.  A farm trailer can be adapted to act as the steam distillation tank.  With this system, the essential oil crop is picked up from the field with a forage harvester and placed into the specially adapted trailer.  The lid is securely fastened and the trailer is taken to a farm building containing the other steam distillation equipment.  A steam inlet pipe can be attached to the trailer, the trailer placed in a vertical position and the outlet pipe attached to the top and the steam supplied.  Steam containing the essential oil is conveyed out of the trailer into the condenser unit.  Adaptations to the trailer include a lining of stainless steel, insulation and anti-reflux systems.