Several key bottlenecks in the willow crop production system have been overcome during the past few years, making deployment on a large scale possible. One of those barriers has been availability of large quantities of shrub willow planting stock. Over the past few

years a commercial nursery in western New York (Double A Willow) planted over 60 ha of willow nursery beds to meet the projected annual demand for millions of planting stock cuttings and several other nurseries are being planned.

Another significant bottleneck has been how to efficiently and economically harvest the crop and produce a consistent quality product that is acceptable to end users. Since 2004, Case New Holland (CNH) has been working with SUNY-ESF and other partners to develop a harvesting system for willow biomass crops based on a New Holland self-propelled forage harvester and a header that is designed to cut short rotation woody crops. Trials with the latest version of this system, based on a New Holland FR series self-propelled harvester and a 130 FB coppice header, indicate that for three or four-year-old willow biomass crops with the majority of stems <75 mm in diameter, consistent high quality chips (>95% of the chips being smaller than 37.5 mm) can be produced at a harvest rate of about 0.8-1.8 ha h-1. Additional actions are being tested to further improve this machine [35]. As noted above, the improved production rates that are possible with this harvester will have a direct impact on the delivered cost of willow biomass.

12.2 Conclusions

In order to meet the projected demand for biomass for the production of bioenergy, biofuels, and bioproducts in the United States, perennial energy crops will need to be developed and deployed across millions of hectares over the next 25-30 years. Over the past few decades, research in Europe and North America has resulted in the development of a shrub willow production system. Thousands of hectares of shrub willow crops have been deployed in Europe, and the system is beginning to be expanded in the United States, but the future of it as a sustainable system will depend on continued research on biological, ecological and socioeconomic factors, development of a feedstock production and supply infrastructure, and supportive renewable energy policies.

Many characteristics of shrub willows, and the production system that has been devel­oped, contribute to sustainability of the system. The perennial nature of willows, their extensive diffuse root system and the coppice management approach that has been devel­oped, result in a crop that can be maintained and productive for more than two decades after it is planted. These characteristics create tight nutrient cycles and a permanent crop on the landscape that will improve soil and water quality as well as biological and landscape diversity relative to traditional annual agricultural crops. The potential of the system to sequester greenhouse gases and its high-energy return on investment are other key features that contribute to its sustainability.

Under existing policy structures, the economics of willow biomass crops are marginal because of the relatively high cost of establishment, low prices for woody biomass, and limited experience with the crop. In addition to optimizing the production system and improving yields, changes in policies to support commercial deployment of willow and other perennial energy crops in the near term are necessary to transition these crops to commercially viable systems. Recent development of the USDA BCAP project in northern New York is a positive step forward. As this and subsequent expansions occur, potential socioeconomic benefits associated with producing a marketable product from marginal agricultural land should begin to accrue to rural areas. Since biomass from shrub willow crops will be integrated with woody biomass from other sources, such as low-grade material from forests and residues from forest harvesting operations, there is potential for benefits to accrue to local communities from revitalization of those sectors as well.

The future challenges are to simultaneously optimize willow biomass crop production, increase interest from potential producers, and develop long-term markets for willow and other sources of woody biomass. To accomplish this and develop a sustainable system, strong links between researchers, potential producers, and end users are required. With these links in place, development of a vibrant willow biomass enterprise will play an important role in bolstering the farm and forestry sectors, while increasing energy independence, providing environmental benefits, and mitigating pollution problems.