Biofuel Component Concentrations and Yields of Switchgrass in South Central U.S. Environments

and Vogel, 1995). Morphological type is designated as lowland (tall, coarse stems, adapted to poor drainage) Optimizing biofuel production and quality from switchgrass (Panand upland (short, fine stems, good drought tolerance), icum virgatum L.) may require matching of ecotype and morphological type to environments, particularly in southern regions. Nine while physiological ecotype is determined by latitude genotypes from four combinations of ecotype and morphological switchof origin (broadly classified as northern or southern). grass type were harvested from 1998 to 2000 in five sites across Texas, Because of the strong response of maturation rate to Arkansas, and Louisiana that varied in latitude and precipitation. An photoperiod, northern ecotypes generally have lower additive main effects and multiplicative interaction (AMMI) method cell wall concentration than southern ecotypes at the was used to evaluate genotype environment interaction (G E) same stage of maturity (Buxton and Fales, 1994). Hoppatterns for traits important to biofuel production. Compared with kins et al. (1995) reported that cell wall concentration upland genotypes across all site-years, lowland genotypes had greater and in vitro dry matter digestibility (IVDMD) of switchlignocellulose yields (3.26 vs. 7.40 Mg ha 1), greater removal rates of grass grown in Iowa, Indiana, and Nebraska were relasoil N (41 vs. 83 kg ha 1) and P (6 vs. 12 kg ha 1), greater concentrations tively stable over environments, but that large G E of moisture (394 vs. 452 g kg 1) and cellulose (388 vs. 394 g kg 1), and lower concentrations of N (6.3 vs. 5.7 g kg 1) and ash (48 vs. interactions existed for dry matter (DMY) and cell wall 40 g kg 1). Compared with northern ecotypes, southern ecotypes had yield. Selection efforts focused on improving IVDMD greater lignocellulose yields (4.95 vs. 6.85 Mg ha 1), greater removal for livestock have also produced lower lignin concentrarates of soil N (60 vs. 76 kg ha 1) and P (8 vs. 11 kg ha 1), greater tions (Vogel and Jung, 2001), suggesting that selection moisture concentrations (417 vs. 445 g kg 1), and lower ash concentrain the opposite direction might lead to genotypes with tions (45 vs. 40 g kg 1). Lignocellulose yield paralleled dry matter improved combustion biofuel characteristics. Casler and yield (DMY) patterns. Switchgrass biofuel production efforts in the Boe (2003) reported G E interactions for ash concensouth-central USA should focus on improving DMY of southern lowtration among switchgrass cultivars. The extent of poland genotypes to maximize lignocellulose yields, but management tential G E interactions for other biofuel qualities factors may be more effective in optimizing moisture, ash, and mineral such as harvest moisture and mineral concentrations in concentrations for combustion. switchgrass has not been reported. Moisture is undesirable in combustion processes because additional energy is required to dry material beS is widely adapted across the USA (Moser fore it will burn. Jenkins et al. (1998) stated that 650 g and Vogel, 1995) and has potential as a biofuel for kg 1 of moisture is the upper limit for self-supporting cofiring with coal. Specific target concentrations of combustion of biomass, with wet fuels burning less chemical constituents for optimal energy generation cleanly and requiring a supplemental fuel source to supfrom switchgrass are currently unclear because biomass port combustion when moisture exceeds 500 g kg 1. conversion technology is at a very early stage of developLewandowski and Kicherer (1997) cited 230 g kg 1 of ment (Vogel and Jung, 2001). In general, combustion moisture as the critical maximum for efficient combusbiofuels should contain a high concentration of lignoceltion and safe storage of grass biofuels. lulose as the primary energy-producing substrate with Biofuel ash has several undesirable properties for low accompanying concentrations of water, ash, and N combustion energy conversion processes, and some con(Hohenstein and Wright, 1994). sider it to be the most limiting factor in those processes Morphology and physiology affect lignocellulose con(Jenkins et al., 1998). Compared with coal, biofuel ash centration, and these functions are primarily determined contains more alkali elements that contribute to slagging by photoperiod and precipitation in switchgrass (Moser (formation of deposits on surfaces exposed to radiant heat) and fouling (formation of deposits on heat-recovK.A. Cassida, USDA-ARS-AFSRC, 1224 Airport Rd., Beaver, WV 25813; J.P. Muir, Texas Agric. Res. Station, 1229 North U.S. Hwy. ery surfaces) in furnaces and boilers, agglomerization 281, Stephenville, TX 76401; B.C. Venuto, USDA-ARS-GRL, 7207 of fluidized beds, and corrosion of metal surfaces, all W. Cheyenne Rd., El Reno, OK, 73036; J.C. Read, Texas Agric. Res. of which severely affect operation of power plants Station, 17360 Colt Rd., Dallas, TX 75252; M.A. Hussey, Dep. of Soil (Olanders and Steenari, 1995; Tillman, 2000; Werther and Crop Sci., Texas A&M University, College Station, TX 77843; et al., 2000). Heating value of wood fuels has been negaand W.R. Ocumpaugh, Texas Agric. Res. Station, 3507 HWY 59 E, Beeville, TX 78102. This research was sponsored by the U.S. Departtively correlated with ash concentration (Jenkins et al., ment of Energy’s Biomass Program through contract 19XSY091C 1998), with every 10 g kg 1 increase in ash concentration with Oak Ridge National Laboratory (ORNL). ORNL is managed decreasing heating values by 0.2 MJ kg 1. Tillman (2000) by UT-Battelle, LLC, for the U.S. Department of Energy under contract DE-AC05-00OR22725. Received 11 Feb. 2004. Forage & GrazAbbreviations: AMMI, additive main effects and multiplicative intering Lands. *Corresponding author ([email protected]). action; ANOVA, analysis of variance; DMY, dry matter yield; G E, genotype environment interaction; IVDMD, in vitro dry matter Published in Crop Sci. 45:682–692 (2005). © Crop Science Society of America digestibility; L, lowland morphological type; N, northern ecotype; S, southern ecotype; U, upland morphological type. 677 S. Segoe Rd., Madison, WI 53711 USA 682 Published online February 23, 2005