Creating A Bio Fuel Woodland

So you have a bit of land and want to experience a bit of the "Good Life" by growing your own raw materials and fuel, sounds like heaven.

Normal woodland planting is 2.5m between each tree which equates to 600 trees per acre or 1500 trees per hectare however you can plant at closer intervals for firewood production. The closer intervals help to encourage the trees to grow straighter as they are competing for light and will reach upwards. Planting at 1.5m intervals (1700 trees per acre or 4300 trees per hectare) would be our suggestion as this would provide some early thinnings which means warmer sooner or off the grid earlier. These measurements are not applicable to Willow and Poplar which do come under a different category.

Trees suitable for SRC (short rotation coppicing, harvested 2-5 years) and Energy crops include Willow, and Poplar although Willow far out weighs Poplar for energy crops (odd that Poplar is less popular)

Tree Species suitable for SRF (Short Rotation Forestry, harvested 8-20 years) include: Ash, Alder, Sycamore, Willow, Sweet Chestnut, Birch, and Poplar.

Cuttings Vs Cell Grown Trees

Cuttings offer you a cheaper overall option however the failure rate is much higher than that of cell grown and much more ground preparation is needed. Cell grown trees are available to plant all year round and can be stored much easier. 

Choosing a SRC site

Choose a site with 7% or less gradient for ideal conditions, anything over 15% is not advised. If compacted ground is an issue, sub-soiling to around 40cm is required.
A maximum of 100m above sea level is advisable unless the site is particularly sheltered.
Expect around 30 years productivity from your site before considering replanting.
Considerations for SRC are water, weed control, light and temperature.
Although Willow can handle light soils, the addition of low Nitrogen organic manure will improve the soil considerably. These include farmyard manure and sludge cake.
Best results come from enough water within 1 metre of the soil surface with annual rainfall in the 600mm to 1000 mm range. Seasonal flooding is acceptable but standing water will make the site unsuitable. Soil erosion on sandy sites maybe a problem initially as new SRC sites will be exposed to the wind and sloping sites maybe eroded by large rainfall, think Summer 2012! 
Willow is tolerant of most soil types from sand and clay to reclaimed colliery spoil however sandy or clay sites that retain moisture will give best results especially if in the PH 5.5 to 7 range.

Pros and Cons For Willow SRC

On the Con side: For commercial growers the machinery to administer the crop is mostly limited to the North of England, poor initial cash flow as a full harvest takes three years, mixed plantations may cause harvesting problems, for best price your crop needs expensive processing to cut and dry, large storage area required and can affect land drains if too close.

SRC Land Preparation

Weed control is a priority for your crop. Before planting anything, the site needs to be cleared of weeds. Spraying with Glyphosate in the Summer and then again in the Autumn prior to Spring planting is advised. Some sites may need another application in the Spring. For compacted sites, sub soil to 40cm and then plough to 25cm then leave to over winter. Power harrow just before planting.
 
Rabbits will likely be an issue for the first two years, possibly even up to your first full harvest. Consider rabbit fencing for your whole crop.

Once the first year is out of the way and your SRC crop has become established, the use of herbicides is less important. In fact allowing ground flora to develop will be beneficial as it attracts wild life that eats the defoliating invertebrates, either directly or indirectly.

Willow Planting

Willow is a popular choice (despite the moisture content being 45-60%) if you are patient because planting a new tree can be as straight forward as cutting a branch off of one willow and just sticking the cut end in the ground in Spring. The professional way to take cuttings is to take them from one year wood that is harvested from December to March, plant them straight away or store between -2 to-4 degrees centigrade.

Cuttings will be around 20cm long with a 8 mm minimum diameter and last for several weeks at this temperature and rods (1.5m - 3m) will last for up to 3 months. If in storage, they should be taken out on the day of planting. The longer out of temperature the less viability you have. If you have rods, cut them down to 18-20cm lengths and plant 2-8 cm straight into the ground, firming around the base. 

Willow cuttings are typically planted in Spring, possibly early as February after the last frost or as late as June however earlier is better. Plant at 15,000 per hectare, 12000 if you want thicker stems for improved chip quality. Plant the Willow cuttings in twin rows 75cm apart with 1.5m between each twin row. In other words plant your first row, then plant a second row 75cm away. The third row will be 1.5 m away from the second and the fourth row will be 75cm away from the third.  Another way of describing this is to plant in rows of two that are separated by 75cm. Each row of two is then separated by 1.5 metres.  Plant spaces along the rows should be at 59cm intervals. No This configuration allows standard machinery to work across your harvest. 

Roll the soil after planting for effective herbicide application. Pre-emergence herbicide should be used with 3-5 days of planting. Land that was grassland or not used for a long time then leather jacket pest control should be applied.  Leather Jacket are Crane Flies or Daddy Long leg larvae which is a grey brown cigar shaped grub. Best time to apply this insecticide is at the same time as the pre-emergence herbicide or before root development.

Fertilising Willow Crops

Under the code of Good Agricultural practice for the protection of water 1998, no more than 250 kg of organic Nitrogen per hectare per year should be applied to agricultural land. Luckily, Willow has a low demand for Nitrogen. For the first year after cutback apply 40kg per hectare, followed by 60kg for the second year and 100 kg for the third. If your soil has previously high levels of Nitrogen then these levels should be decreased. Do not apply fertilizer from first planting to first cut back as the root system will not be formed enough to take up the Nitrogen and will just leach away.

Harvest

Cut your Willow down to below 10cm in their first winter to promote multiple stem re-growth. Expect between 5 and 20 shoots. This should be done late in the winter, around late February. A contact Herbicide should be applied after first harvest and before bud break. Generally avoid sytemic/translocated contact herbicides to avoid crop damage although some such as amitrole have been shown to be safe before bud break.

First year trees could get to 4m. Commercial willow growing sites typically harvest at around 8 metres which is around the three year point. A reasonable site can yield 7 to 12 tonnes per hectare (dried wood) from the first year.

After the first one year harvest, your next one at three years should take place mid-October to Early March or if you have wacky weather patterns, after leaf fall and before bud break.
 
The smaller you cut the willow up, the less air will circulate around them leading to possible composting and mould problems. Keeping them as rods with steady air flow around them would be less problematic. Expect a moisture content of around 30% after a few months of being stored in bundles with good air flow around them.

Willow Disease and Problems

Melampsora is an adaptable fungi that causes Rust and infects the stems and leaves. Being adaptable makes it a challenging problem to eradicate.

It is a good idea to mix your Willow species to guard against disease and pest as Rust and Willow beetles will be two of your biggest concerns. The UK and European Plant Breeding Programme suggest planting at least 5 different species at random. This is because the Willow Beetle will favour one species of Willow over another and therefore slow there spread giving you more time to deal with it.  The use of fungicides is not recommended however more information can be found from the Forestry Commission Information Note written by Tubbush, Parfitt and Tubby (2002)

Chrysomelids (willow beetles) will be another enemy of the Willow SRC farmer. They re-produce rapidly in Spring with both adults and larvae eating the leaves. 90% leaf destruction in Summer could lead to 40% reduction at harvest. 

You can find them in the Winter under rotting wood bark in similar habitats a short distance from your Willow SRC.  Warm weather will make them move to the edge of your Willow SRC which is now a food source for them and they will gradually move further into your crop. You have a problem if when shaken, a Willow tree produces more than a 100 adult beetles per square metre. Spraying the whole crop with insecticide is not an option, local application at known hot spots or spraying the perimeter of your crop are the only two feasible courses of action. This is because there are other beneficial insects within your crop that would also be killed.

Having an infestation one year, is not guaranteed you will get another next year. 

Browsing animals could an issue but only in the first year of establishment. The Game conservancy Trust has produced a booklet describing "Integrated Pest Management Techniques For SRC Tucker and Sage 1999)

Other Willow Information

If you do not want to make firewood, Willow was once used to make Cricket bats and charcoal. Future considerations are to use Willow to make bio fuel for our transportation and other engine needs.

Poplar SRC Land Preparation

Same as Willow SRC.

Land for Poplar SRC

Poplar will grow to an acceptable standard in most soil conditions although it prefers deep and fertile. Those that will give you most trouble are shallow and waterlogged. PH between 5.5 and 7.5 are preferable but some Poplar species will tolerate outside of this range.

Planting Poplar SRC

Some species have been bred for SRC, more information on this can be found from the Forestry Commission Note "Poplar and Willow Varieties For Short Rotation Coppice (Tabbush, Parfitt and
Tubby 2002). Poplar is under the control of the "Forest Reproductive Material Regulations" to ensure that only suitable varieties are used.

Poplar planting should take place as early in the Spring as possible but avoid the frost. Density is slightly lower than willow at 10-12,000 per hectare instead of 15,000 for Willow. The Poplar cuttings should be 20-25cm long with an Apical bud within 10mm of the tip and be a minimum of 10mm at its narrowest point. Weed control is important for the first year so use a residual herbicide 3-5 days after planting.

Harvesting Poplar

As with Willow, harvest your Poplar SRC in the first winter to promote extra shoot growth. Unlike Willow, you will only see 1-3 shoots appear in the Spring.
In some situations Poplar can out perform Willow but these appears to be site specific and harvesting every 4 years.

Poplar Disease and Problems
As with Willow, Melampsora and the Willow Beetle are pests to your SRC. Treat as for Willow.

If you want to stop SRC, removing Poplar can be an issue as it has a tap root requiring heavy machinery to remove.  

Buy Willow Trees Online

Buy Poplar Trees Online

Summary

Information about species specific trees for SRC changes regularly due to the problems they face changing quickly and frequently. To that end, to ensure you get the best up to date information, we suggest looking at the following websites:

https://www.forestry.gov.uk/
www.crops4energy.co.uk
wwww.biomassenergy.org.uk