Seasonal dynamics of biomass productivity, combustion quality, and nutrient translocation in bulbous canary grass (Phalaris aquatica L.) in a semiarid Mediterranean environment

In order to achieve sustainable biomass production from perennial grasses, seasonal changes in biomass yield, combustion quality, and nutrient translocation need to be monitored in detail. In this study, the effects of six distinct disruptive harvests (November, January, March, May, July, and September) on the dry biomass yield, ash, moisture, and mineral contents, as well as the composition of the cell walls and the translocation of nutrients in bulbous canary grass, were investigated in a semiarid Mediterranean climate. The September harvest significantly reduced aboveground ash and mineral contents, while their contents in belowground biomass exhibited a significantly increasing trend from May to September, which might be evidence of nutrient mobilization from the shoots to storage organs during the summer dormancy. Additionally, the September harvest considerably improved the combustion quality of bulbous canary grass by reducing moisture content (from 75.35% to 19.23%), ash-sintering index (1.47 to 0.70), and increasing lignin content (8.40% to 13.11%) and lignin/holocellulose ratio (0.151 to 0.187), despite causing a 26% DM yield loss (from 235.8 to 174.9 g plant–1) compared to the May harvest, which coincided with the end of the growing period. However, further efforts are required to reduce the ash and mineral contents of the crop in order to decrease the risk of slagging, sintering, and hazardous gas emissions that may occur as a result of burning biomass.