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a Dep. of Agricultural Economics, Univ. of Tennessee, 2621 Morgan Circle Dr., Knoxville, TN 37996
b Dep. of Biosystems Engineering and Soil Sci. West Tennessee Res. and Educ. Cent., Univ. of Tennessee, 605 Airways Blvd., Jackson, TN 38301
* Corresponding author (dmooney1{at}utk.edu).
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.
Abbreviations: MDSU, moderate to somewhat poorly drained eroded sloping upland PDFP, poorly drained flood plain PLS, pure live seed SR, seeding rate WDFP, well to moderately well drained flood plain WDLU, moderately well drained level upland
1 Cost estimates reported here include establishment, annual maintenance, and harvest costs, plus the opportunity cost of land for a 10-yr production period.
2 Budgeted P and K rates differed from the rates applied in the experiment because P and K recommendations for switchgrass were not developed until after the experiment was initiated.
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Received for publication March 3, 2009.
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