Dynamic change of biomass and quality of switchgrass in different growing seasons

Switchgrass (Panicum virgatum) has the potential to produce biofuel from its lignocellulosic feedstock. A field experiment was conducted to evaluate the dynamic change of biomass yield and qualities of switchgrass (P. virgatum cv. Alamo) in different growing seasons in Beijing, China. The results showed that the aboveground biomass of switchgrass was highest in late August, and gradually decreased by 23% (from 20.3 to 15.2 t·ha-1) in late October and decreased by 30% in late November. There were significant dynamic various for switchgrass qualities in different growing seasons. The nitrogen and chlorine concentrations increased firstly and then decreased with a peak value at anthesis stage in late August. The heat value, volatile, hemicellulose, lignin contents increased, and the water, ash, fixed carbon, cellulose, phosphorus, potassium, sulphur contents decreased. The offtake of all elements measured in this experiment reached the peak value in late August which suggest that late October was optimal for harvest with better qualities and higher biomass yield for Alamo in Beijing.