Farm Ireland

Saturday 21 April 2018

Branch out with eucalyptus

Some varieties of the tree can survive frosts of -16°C and, with their rapid growth rates, appear ideal for growing for energy production
Some varieties of the tree can survive frosts of -16°C and, with their rapid growth rates, appear ideal for growing for energy production
Joe Barry

Joe Barry

Most of us are constantly looking for new crops that will leave a reasonable profit without the weather risks associated with growing grain.

Formerly, we farmed almost exclusively to produce food but now we are being urged to grow more crops for energy use.

It is worth noting how words like sustainable, renewable and recyclable have crept in to our everyday language along with bio diverse, bio degradable, carbon neutral and so on.

Everyone is familiar with the arguments relating to the environment, the dangers of greenhouse gas emissions and the most popular topic of all, how to heat our homes economically.

Green energy crops are gradually gaining a foothold and even grain is being grown to burn for heat. That seems somehow like a waste of good food, but the argument goes that if you feed it to a horse it produces energy so why not feed it to a stove.

I have always been sceptical regarding the merits of making wood chip or wood pellets. A basic log, once dry, makes excellent fuel without the high energy requirement and costs of further manufacturing.

I also feel that there are still questions to be answered regarding the economics and viability of producing willow or miscanthus for energy production and feel more at ease with the concept of planting fast-growing tree species to supply our heating needs.

Trees are relatively straightforward to harvest and for smaller operations, one only needs the most basic of equipment. This line of thought is of course not considered fashionable at present but then often the wisest and safest move can be to resist fashion and avoid costly capital investments.

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Acacia has often been touted as the fuel crop of the future, but last winter’s severe frosts dampened the enthusiasm for it.

Eucalyptus, however, has been grown under trial in Ireland since the 1930s and numerous experiments have taken place to assess its viability for construction and other uses. The wood is difficult to mill, however, so the timber industry lost interest.

But with the recent demand for alternative crops for energy use and especially for home heating, people are taking a second look at this wonderful tree and its amazing growth rates. When cut into logs or chipped, eucalyptus makes excellent fuel and can be harvested on an eight-year rotation. Most varieties coppice well and the speed of regrowth is astonishing.

It can deliver approximately 16t of dry wood/hectare and you can repeat the process three times before needing to replant.

Brendan Doyle of D Plant Horticulture has been undertaking trials of differing species of eucalyptus and he believes that it has a sound commercial future in Ireland. I understand that COFORD and Coillte are also examining its potential.

Some varieties can survive frosts of -16°C and with their rapid growth rates and ability to coppice they would appear ideal for growing for energy production.

I have grown eucalyptus for 15 years as a foliage crop but had not considered it for use as a wood fuel. To find out some more I visited the D Plant nursery at Glenbrian near Enniscorthy, Co Wexford and found that they are already producing transplants for sale to many outlets, including the British Forest Commission.

Eucalyptus is planted and grown in almost exactly the same manner as any forest tree. Two metre spacings are best and weed control is required for the first two years.

It will grow well on heavy soils but should ideally be grown on good, free-draining land. The wood splits easily and is perfect for open fires, stoves and log gasifier boilers and Brendan said it can produce up to double the yield of willow.

Matching the species to the site is important. Three crops can be harvested before replanting taking place at year 24. This relatively short rotation looks attractive, as do the high yields and volume of wood produced.

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Irish Independent