Biomass Yield and Nitrogen Response of Perennial Bioenergy Grasses in North Carolina.

Perennial grasses are attractive candidates for bioenergy production that can exhibit significant biomass yields while requiring relatively few agronomic inputs. However, adaptability and yield of perennial grasses can vary considerably by region.  Because candidate grasses are diverse and information on regional yields and suitability are often lacking, an assessment of performance under different conditions is an integral component of the transition towards large scale bioenergy production. In this study, biomass yield, nitrogen response, and regional adaptability of selected grasses were evaluated over 3 years at 2 locations in North Carolina as part of an ongoing effort to develop improved plants and production practices. Field trials were established in 2008 at Mills River (Mountains) and Wallace (Coastal Plain), NC. Treatments included 7 taxa (Arundo donax, M. ×giganteus, M. sinensis H2006-006-001, M. sinensis ‘Gracillimus’, S. ravennae, S. arundinaceum, and P. virgatum ‘Alamo’) and 4 N rates (0, 34, 68, 136 kg N ha-1) arranged in a completely randomized factorial containing 28 plots at each of the 2 locations. Transplants of all grasses, except switchgrass, were planted on 1 x 1m spacing with 25 plants per plot.  Switchgrass was seeded in 12 inch rows at 8 kg ha-1. Plots were harvested in late December/early January of 2008-2011, and a biomass subsample collected for measurement of moisture and nutrient content. Individual taxa varied in survivability and yield between the 2 sites.  Among the taxa, and year 3 yields ranged from 5-34 Mg ha-1 and N removal ranged from 32-175 kgN ha-1.