Mineral Composition and Removal of Six Perennial Grasses Grown for Bioenergy in the Southeastern USA.

Bioenergy crop mineral composition influences suitability for conversion to energy, and soil nutrient removal impacts fertilization and economics of production. However, relatively few data are available on mineral composition and removal for perennial bioenergy crops in the southeastern USA. This study was conducted at three locations in Florida comparing biomass yield, mineral composition, and mineral removal of sugarcane (Saccharum spp. hybrid), energycane (Saccharum spp. hybrid), sweetcane [Saccharum arundinaceum (Retz.) Jesw.], elephantgrass [Pennisetum purpureum (Schum.)], giant reed (Arundo donax L.), and giant miscanthus [Miscanthus x giganteus (Greef and Deuter ex Hodkinson and Renvoize)] during 2009 and 2010. Tissue ash concentrations were very similar among species at each site. However, mineral concentrations varied by site and species. Giant miscanthus had the least dry biomass yields (13.5 ha^-1), followed by giant reed (23.8 Mg ha^-1), which had lesser dry matter yield than the remaining species (35.3 Mg ha^-1). Giant miscanthus contained less moisture than all other species at each site. Across treatments, leaves accounted for only 23% of total biomass. Total N, P, and K removals were highest for sugarcane, sweetcane, energycane, and elephantgrass and averaged 179, 41.2, and 279 kg ha^-1, respectively and lowest for giant reed (147, 20.2, and 157 kg ha^-1) and giant miscanthus (56, 12.2, and 46 kg ha^-1). Results indicated that relatively high dry matter yields desirable for bioenergy production can be achieved using perennial grasses in the southeastern USA, but moderate to high fertility inputs will likely be needed to sustain high production levels.