Growing Fire Wood Logs from Willow

Introduction

Growing biomass willow cuttings in short rotation coppice is the fastest way to grow your own wood fuel and fire wood. Willow logs can be used in wood burners or log boilers, chipped willow is an ideal fuel for automated biomass boilers. You can have your first wood fuel harvest just 3 years after planting and can realistically expect a harvest of 8-10 tonnes of dry wood per hectare per year.

 Short rotation coppice (SRC) is already used in large scale wood fuel production for power stations, normally as wood chip and automated domestic woodchip boilers are becoming more popular as oil prices continue rising.

Planting and harvesting your own fire wood crop is straight forward and can be done without specialist equipment. Harvesting the wood fuel is done near ground level, easy to cut and access. The size of logs produced on a 3 to 6 years rotation will vary from 2 to 4 inches in diameter, no need for splitting. You can vary the time between harvesting to suit your needs or the size of your wood burner. Willow for wood chip can be harvested on shorter rotations, giving higher yields. By dividing your coppice into four or more sections and harvesting in rotation you will have a ready supply of logs, year after year.

Benefits of SRC Willow

The major reasons for growing willow rather than other firewood crops are;

• · It has the shortest time to harvest of any woodfuel
• · It is environmentally beneficial – willow supports the greatest range of wildlife of any single crop grown in the UK, willow trees can be the home to a staggering 450 different invertebrates.  SRC willow plantations have been shown to support 50 different bird species.
• · It is the highest yielding woodfuel crop growing in the UK.
• · It is easy to harvest and handle.

  Mammoth Willow cuttings are all proven biomass varieties suited to UK conditions. We supply a mix of five varieties of willow in the woodfuel growing kits. Each has its own growing habit. Initially you will notice significant variation in the size of the willow plants, this is normal and by the time of harvest most varieties will be of equal size at around 14 to 20 feet. The genetic diversity ensures that you willow plantation is less vulnerable to pests, diseases and climate variations resulting in higher yields.

Our low Carbon SRC system.

This fire wood growing guide focuses on a no till pesticide free production method suited to planting in uncultivated grassland, for which Mammoth Willow’s wood fuel kits have been designed. By planting through a permeable plastic membrane you can plant into grassland without ploughing and cultivating the soil. This reduces the work required and significantly reduces time to achieve carbon payback compared to spraying, ploughing and cultivating grass land for planting. The membrane also negates need to use weed killers to kill competing plant life. Although the plastic used does have an environmental impact it is less than cultivating previously uncultivated land.

There are four easy stages to planting using our system.

• 1. Lay the groundcover sheeting down and peg it every metre. Refer to the diagram showing spacings.
• 2. Make a planting hole with metal rod, pierce through the ground cover.
• 3. Place the sett in the hole.
• 4. Place wire pin/peg next to the cuttings, to prevent the groundcover lifting up in the wind.

Where to Grow your Short Rotation Coppice.

Willow can be grown successfully on a wide range of soil types but very wet soil which remains waterlogged for much of the year can prevent some unrooted cuttings from forming roots successfully. Very dry soils or very sandy soils are also best avoided. As with any crop willow will grow best on fertile soil and willow does like water so long as it’s not standing in it for months.

Preparing the planting area.

Your willow plantation should be planned for easy access. The spacings between groundcover rows suggested below can be varied to suit the equipment you use. You will need to mow between the rows during spring and early summer in the first two years so space your rows for easy mowing (we use a mower with a 1 metre cutting bar). You will also want to ensure access for a trailer, the spacing below assumes that a vehicle and trailer will be used. Once a row has been harvested the vehicle and trailer will be able to drive up that row straddling the coppiced willow stools. Allow for turning space at the end of rows. If you are growing on a steep hill it is normally easier to run the rows up and down the slope. Because groundcover vegetation is maintained between the rows erosion is not normally a problem. Even if you plan on carrying the harvested willow out on your back don’t reduce the space between the rows below that suggested. 

(in our kits we use 75cm for larger kits and 50cm spacing for starter kits)

 Prior to laying your groundcover sheeting you may want to mow the planting area if the grass and weeds are long. This will ensure that the groundcover is not lifted by the wind. As you unroll your groundcover peg it down at 1 metre intervals using the pegs supplied, in soft ground you can just push in the pegs, in harder ground you will need to use a hammer. The pegs should be pushed through the plastic around 5cm from the edge to ensure it doesn’t fray. At extremely windy sites you may need to weigh down the groundcover as well.

 Rabbits

If rabbits are likely to be a problem consider fencing the whole area with 1050mm high rabbit netting. Fencing is relatively easy as it does not need to be dug in and posts can be spaced quite widely. The netting fence should be a minimum of 90cm (35") high with a further 15 cm (6") lapped on the surface of the ground to the outside of the fenced area. Turfs of grass should be placed on the lapped netting at 1m (3') intervals to hold it firmly in place; vegetation will later grow through the mesh to complete this job. The netting should be attached to straining wires (one at the bottom of the fence and one at the top) with galvanised fence rings or thin galvanised wire and the straining wires supported by wooden fencing stakes (2-3") in diameter. The 5ft or 6 ft high stakes can be placed  5m apart. End posts 2.1m (7') high, and 10-12½cm (4-5") in diameter, need be placed only at the ends of the fence and at bends. The wire netting should conform to the British Standard which measures mesh size across the widest part of the hexagon. 31mm (1") BS mesh,  18 or 19 gauge.

Planting Your Willow. It is important that the setts (unrooted cuttings) are planted as quickly as possible. If it is not possible to plant immediately then store them in a cool shaded place in the bag they came in. Warm conditions will cause root growth, this must be avoided. In winter, setts may be stored for a short time before planting, so long as they are kept cool (0-5degC) and out of direct sunlight.

The 1 foot willow cuttings supplied should be planted so that 3 inches are visible above the plastic. A metal rod 1/2 inch diameter should be used to make a planting hole. A crow bar, long masonry chisel or metal reinforcing bar will all do the job for small quantities of willow. The metal rod needs to be hammered through the plastic into the ground and retracted leaving a planting hole 9 inches deep. Place the sett in the hole, with the tiny buds pointing upwards. For larger quantities a rod with a cross piece welded 9” from one end and a handle on the other end should be used so that you can push with your foot like a spade.

It is also advisable to pin down or weigh down the ground cover next to the setts(2 inches/5cm away), to stop the wind blowing the sheeting up ,we make our own wire pins from 2.5mm fencing wire cut into one foot lengths, bent into a U shape. Other people have used stones, old bricks or shovelled on gravel to weigh down the groundcover.

Maintenance during the first 2 years.

During the first spring /summer mow the grass isles 2 or 3 times, to keep down the surrounding grass and weeds. By July your willow should be taller than any surrounding grass. Keep an eye out for nibbled willow, almost always caused by rabbits, if you haven’t fenced then do so. If you experience an exceptionally dry spring your willow may suffer, although we haven’t yet had reports of more than 5% failure during a very dry spring.  At the end of the first growing season slit the groundcover plastic around the base of each willow plant to stop it constricting the trunk. A Stanley knife is ideal; the cut should be at least 6” (15cm).If you have used wire pins or pegs next to your setts then remove them, this will prevent damage to the willow as it grows.

Management for logs

Short Rotation Coppice is often cut back at the end of the first growing season to encourage multiple stems to develop and increase yields. However if you are growing for logs rather than chips, a more useful harvest will be achieved  if you don’t cut back and allow fewer, thicker branches to develop.

Fertilising

No fertilisers are required to grow willow. However cattle slurry has been shown in trials to improve yield of short rotation willow crops on poor quality soil. This should only be done when the willow is fully established and ideally done after harvesting the willow for wood fuel.

Managing Pests and diseases

Willow attracts a wide range of bugs, but most are harmless and the costs and disadvantages of spraying outweigh any benefit. The major disease affecting willow is rust; you will almost certainly come across this at some point (orange coloured deposits on the underside of the leaves). Rust will have an impact on the yield, but we supply a mix of willow which display good resistance.  In dry periods the lower leaves of most willow will yellow and drop, this is normal.

Harvesting

You can harvest your willow in the 3^rd or 4^th year. However if you want larger logs you can extend the rotation up to 6 years. Harvesting takes place in winter anytime once the leaves have fallen. It is best to cut down your willow before February as some varieties will start growing then. When harvesting cut back each stem to within 4” (10cm) of the ground. The cut branches can be allowed to dry in the field for a few weeks before being collected up to be logged and stacked for seasoning. Thinner willow whips make good kindling when dried. For the highest yield, use all of the harvest  even the small stuff.

Growth in the second and subsequent rotations is normally more vigorous than the first. At this stage the willow can benefit from any added nutrients available from slurries and manures.

If you wish you can remove the plastic groundcover after the first harvest as the willow will now out compete the grass.

Drying and storage

Willow logs need to be seasoned for at least 12 month; kindling (up to 1” diameter) can be used 6 months after being cut. Logs should be dried off the ground; those in contact with the ground will rot. Ideally after 6 months logs should be placed in an open sided log shed to season.

Kindling can be dried in bags made of a material similar to the woven ground cover we supply. Builders dumpy bags are ideal and can also be used for logs.