Shrub Willow Biomass Production Ranking Across Three Harvests in New York and Minnesota

Shrub willow has potential for being a viable dedicated bioenergy crop in temperate northern latitudes of the USA. Selection of high-producing willow cultivars is critical for economic viability and long-term sustainability of willow production systems. Long-term trials are needed in different geographic areas to better understand genetic by environment interactions on biomass yield for greater profitability and to enhance future breeding efforts. Field trials were conducted in two contrasting environments, northern New York and southern Minnesota, to explore changes in shrub willow yield ranking over three harvest cycles across a range of cultivars and diversity groups. Overall, the MN site produced higher, more stable biomass yields than the NY site due primarily to more productive soils, warmer climate, and less weed pressure. However, between-site differences in willow biomass yield were nominal after the second harvest cycle. Yield variability among the top five willow cultivars at each harvest was significantly less than variability among all cultivars regardless of site. Shrub willow cultivars identified in the top-ranking groups were different between sites. Results show that willow can be a viable long-term crop for sustained biomass feedstock production across a wide range of soils and climates but proper cultivar selection is critical for biological and economic success.