Yield and breakeven price of ‘Alamo’ switchgrass for biofuels in tennessee
Research on how land suitability affects yields and breakeven prices for switchgrass (Panicum virgatum L.) grown as a bioenergy crop is lacking for the U.S. Southeast. Data from a 3-yr multilocation experiment at Milan, TN, were analyzed to determine the influence of soil drainage and landscape position on switchgrass yield and farm-gate breakeven price. Plots were seeded in 2004 with ‘Alamo’ at 2.8, 5.6, 8.4, 11.2, and 14.0 kg ha–1 pure live seed (PLS). Plots were split in 2005 and N was applied at 0, 67, 134, and 201 kg N ha–1. Farm-gate breakeven prices for 5- and 10-yr production contracts were determined by calculating unit production costs from enterprise budgets that varied by input level and yield. Maximum yields occurred at 67 kg N ha–1 on well-drained soils and at higher N levels on less-well-drained soils. Yield response to seeding rate (SR) was insignificant or small relative to other factors. Averaged across treatments, the well-drained upland location suitable for row crops had the largest yield (17.7 Mg ha–1) and lowest breakeven price ($46 Mg–1) for a 10-yr period. In contrast, the poorly drained flood plain location considered marginal yielded lowest (8.5 Mg ha–1) and had the highest breakeven price ($69 Mg–1). Breakeven prices were sensitive to yield, N price, and fuel price. Results suggest a lower breakeven price for switchgrass in the U.S. Southeast as compared with other U.S. regions, mainly due to high yields for the Alamo variety.