First-Rotation Yields of 30 Short-Rotation Willow Cultivars in Central Saskatchewan, Canada

Abstract

The Government of Saskatchewan is evaluating whether biomass crops can be successfully used as an affordable, reliable, and environmentally sustainable bioenergy source. The objective of this study was to determine the first 3-year-rotation biomass yields of 30 willow cultivars planted in central Saskatchewan. Annual willow morphological data were collected throughout the first rotation, and stem biomass equations were developed. A willow yield map was produced for the SV1 cultivar across climates and soils of Saskatchewan. The majority of willow biomass equations were with high R2 values (>0.90), and there was a strong agreement between equation-derived yield and harvested biomass (RMSE = 13.6 %; bias = -3.3 %). The average diameter, height, and stem count of 3-year-old stems were 14.1 (standard deviation (SD) =1.7) mm, 304.7 (SD = 45.4) cm, and 8.7 (SD = 1.8), respectively. The average first-rotation harvested yield was 10.5 (SD = 3.3) Mg ha−1, and the average survival rate was 81 %. Simulated SV1 productivity was 13.6 and 11.8 Mg ha−1 across marginal agricultural lands of the Prairies (1.7 million ha) and Boreal Plains (0.4 million ha) ecozones, respectively. Low growing degree days, heavy clay soils, low nitrogen availability, and winter stem dieback at these northern latitudes were the main factors to influence willow production at relatively lower yields observed in this study. Based on first-rotation results, the Tully Champion cultivar had the highest potential to be utilized as biomass feedstock in Saskatchewan, producing 17.4 Mg ha−1, which was 70 % greater biomass than the average yield of the other 29 cultivars. The use of willow as a bioenergy source appears promising, but further research is needed.