Willow wood properties, production and economy

Over the last Few years, selected and genetically improved willows have been introduced as a new crop on farmland with short-rotation coppice systems. The willow wood is used mainly as a biomass fuel. The introduction of willow plantations has been fast in a few areas in northwest Europe and there is still a lot of research and biological and technical development needed for further improvement. Since large-scale willow plantations for biomass fuel constitute a new crop and the willow species come from a very old and wide-spread genera, the potential for improvement is large. The water content in stems at harvest is around 50%, and may be reduced to 25-30% in non-chipped stems after drying during one summer. The calorific heat value of willow wood has been determined to be 19.7 MJ/kg. The ash and sulphur contents are low, 1.0-1.2% and 0.03%, respectively. Nitrogen, phosphorus and potassium in the wood constitute about 0.5%, 0.09% and 0.3%, respectively. Among the metals, cadmium seems to be somewhat higher in willow wood than in wood from conventional forests, namely in the range of 0.8-2.9 mg/kg as compared to < 0.15 mg/kg. In production systems of willows in short-rotation forestry, planting, harvest and handling require specifically unique techniques, which have been developed over the last few years. The economic result for the farmer of willow wood production systems is comparable to the economic results of conventional food crops. Copyright (C) 1996 Elsevier Science Ltd.