Biomass yield, nutrient concentration and nutrient uptake by SRC willow cultivars grown on different sites in Denmark

Abstract

Yield and nutrient uptake of willow cultivars are important factors for long-term feasibility and sustainability of willow short rotation coppice (SRC). This study investigated biomass yield of eight willow cultivars (Inger, Klara, Linnea, Resolution, Stina, Terra Nova, Tora, Tordis) during two three-year harvest rotations on four Danish sites. Also, concentration and uptake of N, P and K was measured in harvested biomass in 2nd harvest rotation on two of the sites.Dry matter (DM) yield differed significantly between sites in both 1st and 2nd harvest rotation, but the relative difference between sites decreased from 106 to 54 %. Mean DM yield across cultivars and sites increased 67 % from 1st to 2nd harvest rotation but ranging from 44 to 108 % between sites. There were certain significant differences in yield ranking of cultivars between sites and harvest rotations but, overall, ranking was rather consistent. Across all four sites and all six growth years, there were four cultivar groups differing significantly in DM yield, with highest yield in Tordis and Tora, second highest in Klara and Resolution followed by Terra Nova and Inger and lowest yield in Linnea and Stina, with Stina having 39 % lower yield than Tordis.Concentration and uptake of N, P and K in harvested biomass in 2nd harvest rotation differed significantly between cultivars and between sites. Across cultivars and sites, nutrient concentration decreased linearly with increasing DM yield, whereas nutrient uptake increased linearly. These results have implications for nutrient balance and fertilization strategies for willow SRC.