BIOMASS YIELD, COMPOSITION AND PRODUCTION COSTS FOR 8 SWITCHGRASS VARIETIES IN ALABAMA

The objective of this study was to determine the yield, chemical composition and production costs of eight switchgrass (Panicum virgatum L.) varieties grown in the southeastern USA. Plots were seeded during the summer of 1988 and were harvested twice in each of the two subsequent years. Samples taken in 1990 were analyzed for nitrogen and several fiber components. Total 1989 dry biomass yields of "Alamo" and "Kanlow" were 17.5 and 13.8 Mg ha-1, respectively. Yields provided by the other six varieties averaged 8.6 Mg ha-1. In 1990, total yield almost doubled for "Alamo" (34.6 Mg ha-1) and increased 68% for "Kanlow" (23.2 Mg ha-1), over that achieved the previous year. Average yields of the other varieties increased slightly to 9.4 Mg ha-1. Variation in chemical composition among varieties was low. In 1989, production costs per Mg DM ranged from $19.70 and $24.91 for "Alamo" and "Kanlow", respectively, to an average of $40.28 for the other six varieties. In 1990, costs fell to $9.94 and $14.82 Mg-1 for "Alamo" and "Kanlow", and to $37.65 Mg-1 for the other varieties.