Methane yield from switchgrass harvested at different stages of development in Eastern Canada

Mesophilic methane yield of ensiled switchgrass grown in Eastern Canada was assessed. Switchgrass was harvested at three stages of development, corresponding to mid-summer, late summer and early fall in 2007. The regrowth of plots harvested in mid-summer was also harvested in early fall as a two-cut strategy. Specific methane yields decreased significantly with crop maturity from 0.266 to 0.309 (N)L CH(4)g(-1) VS in mid-summer to 0.191-0.250 (N)L CH(4)g(-1) VS in early fall; values were similar for the first harvest in late July and the second harvest (regrowth) in October. Approximately 25% more methane was produced by hectare for the two-cut strategy (2.90-3.44 x 10(6)(N)L CH(4)ha(-1)) compared to the one-cut strategy with a harvest in late summer (2.28-2.77 x 10(6)(N)L CH(4)ha(-1)). Methane yields from switchgrass grown under the cool humid climate of Eastern Canada suggest that this crop remains an interesting renewable alternative energy source.