Switchgrass and Giant Miscanthus Biomass Production on Reclaimed Mine Lands

Growing food crops for biofuel on productive agricultural lands may become less viable as requirements to feed a growing human population increase. This has increased interest in growing cellulosic biofuel feedstocks on marginal lands. Switchgrass (Panicum virgatum) and Miscanthus (Miscanthus x gigantea), two warm-season perennials, are viable bioenergy crop candidates because they produce high yields on marginal lands under low fertility conditions. In other studies, switchgrass dry matter (DM) yields on marginal croplands varied from 5.0 to 10.0 Mg ha−1 annually. West Virginia contains immense areas of reclaimed surface mined lands that could support a biomass-based industry but yield data on these lands are lacking. Field experiments were established in 2008 to determine yields of three switchgrass cultivars on two West Virginia mine sites. One site reclaimed with topsoil and municipal sludge produced biomass yields of 19.0 Mg DM ha−1 for Cave-in-Rock switchgrass after the sixth year, almost double the varieties Shawnee and Carthage, at 10.0 and 5.7 Mg ha−1, respectively. Switchgrass yields on another site with no topsoil were 1.0 Mg ha−1 after the sixth year, with little variation among cultivars.

At a different reclaimed mine site following 25 years of herbaceous cover, vegetation was killed and plots of switchgrass (cultivars Kanlow and BoMaster) and Miscanthus (lines Illinois and MBX-002) were planted in five 1-ac replications. Annual switchgrass and miscanthus yields averaged 5.8 and 8.9 Mg dry matter ha−1, respectively, over a four-year period.

Jeff Skousen
West Virginia University, Morgantown, United States