Harvest Of Green Willow Biomass For Feed - Effects Of Harvest Time And Frequency On Yield, Nutrient Concentration, Silage Quality And Regrowth

This study investigated the effects of harvest time during the growth season on yield, quality and regrowth of willow. An eight-year-old willow field was harvested in April 2017, and biomass was harvested either once during 2017 on five dates from 13 June to 27 October, harvested twice in June and October or not harvested in 2017. Biomass yield, nutrient uptake and silage quality were measured for 2017 harvests, and regrowth yield was measured in November 2018. Postponing harvest from June to October increased dry matter (DM) mass fraction from 17.4 to 42.8% and decreased the concentration of ash, N, P and K in DM with N decreasing from 33.3 to 9.7 g kg(-1). pH in willow silage decreased with the later harvest. DM yield increased from 1.1 to 5.8 Mg ha(-1)from June to September and decreased to 4.5 Mg ha(-1)in October, and two harvests in 2017 only yielded 2.2 Mg ha(-1)in total. The sum of DM yields in 2017 and 2018 were 11.4 Mg ha(-1)without harvest in 2017 and ranged between 5.2 and 9.8 Mg ha(-1)when harvested in 2017.