Switchgrass As a Bioenergy Crop a Publication of ATTRA - National Sustainable Agriculture Information Service • 1-800-346-9140 •
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ATTRA Switchgrass as a Bioenergy Crop A Publication of ATTRA - National Sustainable Agriculture Information Service • 1-800-346-9140 • www.attra.ncat.org By Lee Rinehart Switchgrass is a native warm-season, perennial grass indigenous to the Central and North American NCAT Agriculture tall-grass prairie into Canada. The plant is an immense biomass producer that can reach heights of 10 Specialist feet or more. Its high cellulosic content makes switchgrass a candidate for ethanol production as well © 2006 NCAT as a combustion fuel source for power production. This publication discusses agricultural production aspects of switchgrass. Varieties, seed sources, crop establishment, management, and harvesting issues are presented. Ecological considerations are also discussed and a case study is presented along with references and further resources. Contents Introduction ..................... 1 Description, Range, and Adaptation ........................ 2 Switchgrass Ecotypes and Varieties .................... 2 Establishment, Manage- ment, and Harvest ......... 3 Ecological Consider- ations: Prairies and Farmscapes ....................... 6 Feedstock Quality .......... 7 Economics and Multiple Uses of Switchgrass ....... 7 Other Cellulosic Feedstocks ........................ 9 References and Resources ......................... 9 Photo courtesy of USDA NRCS. Introduction stored in plant tissue. Biofuels are renew- able in that plants grow back after harvest, This publication details the production and can be regenerative when sustainable of switchgrass for use as a cellulose-to- methods are employed to manage, harvest, ethanol and direct-combustion feedstock, and process the crops. Ethanol, used in ATTRA—National Sustainable and focuses on the agronomic and eco- gasoline (spark-plug) engines, is produced Agriculture Information Service through the fermentation of plant sugars is managed by the National Cen- logic considerations of switchgrass produc- ter for Appropriate Technology tion. Ethanol production is addressed in and distillation of the mash to produce fuel (NCAT) and is funded under a alcohol. Ethanol can be produced from grant from the United States detail in the ATTRA publication Ethanol Department of Agriculture’s crops such as corn and sugarcane, which Rural Business-Cooperative Ser- Opportunities and Questions. vice. Visit the NCAT Web site are high in the sugars needed for fermen- (www.ncat.org/agri. Biofuels are carbon-based energy sources tation, or from cellulosic materials, such as html) for more informa- tion on our sustainable taken ultimately from solar energy as it wood by-products and high-fi ber grasses, agriculture projects. /$"5 is captured through photosynthesis and such as switchgrass. Switchgrass can also be directly com- (sunfl owers, gayfeather, prairieclover, prairie busted or co-fi red with coal to lower emis- conefl ower). These widely adapted species sions associated with the burning of that once occupied millions of acres of tall-grass fuel. However, for switchgrass to become prairie. Now they are rarely seen, usually practical as a directly combusted fuel on land that cannot be utilized for annual in coal plants, retrofitting current boil- cropping. Look for native plants like these in ers from coal or co-fired applications is protected areas along fencelines, in riparian required. For more information on this buffers, and especially in old cemeteries and aspect of switchgrass, see the Chariton church yards across the prairie states. Valley Biomass Project case study below. Switchgrass grows well in fi ne to coarse tex- Related ATTRA Switchgrass can be used as a fuel source tured soils, and in regions where annual pre- Publications to power ethanol plants, which results in cipitation falls between 15 and 30 inches or Alternative reduced use of fossil fuels and contributes more per year. It is an immense biomass pro- Agronomic Crops to a more positive energy balance for cellu- ducer, and can reach heights of 10 feet or losic ethanol. more in wetter areas of the country. In gen- Alternative Soil eral, ecotypical differences are related to local Amendments Although recent news has been full of excit- soil and climatic characteristics, with eastern Biodiesel—A Primer ing reports about ethanol and switchgrass, and southern varieties adapted to higher mois- producers need to be aware that a market for Biodiesel: ture conditions, and western and northern switchgrass as an energy crop is (in 2006) varieties adapted to drier conditions. The Sustainability scarce to nonexistent. There is intense spec- Dimensions ulation about how, when, and whether these Converting Cropland potential markets will materialize. In the Switchgrass Ecotypes to Perennial Grassland meantime, corn ethanol is becoming more and Varieties Ethanol Opportunities popular in the marketplace. In fact, 14 per- As switchgrass evolved across North Amer- and Questions cent of the 2005 U.S. corn crop was used ica, different ecotypes emerged with genetic Nutrient Cycling to produce ethanol, and the percentage is and morphological characteristics that pro- in Pastures expected to grow. Cellulosic ethanol produc- vide a good “fi t” to a particular place. Thus tion is, from a processing and distribution ecotypes in the south typify southern char- standpoint, still in a research and develop- acteristics, such as long season growth and ment phase. As further research into cel- subsequent high dry matter yield, given lulosic ethanol production and process- favorable growing conditions. ing is completed, perhaps switchgrass can Two major types have emerged through nat- become a cost-effective, viable alternative ural selection. The upland types favor drier energy source. soils and fare better in semi-arid climates. The lowland varieties grow better in heavier Description, Range, soils and are found where water availability and Adaptation is more reliable. The lowland cultivars have the genetic ability to produce more dry mat- Switchgrass (Panicum virgatum L.) is ter than the upland cultivars. a native warm-season, perennial grass indigenous to the Central and North Plant breeders at various Agriculture American tall-grass prairie. It is found Research Stations from Texas to Nebraska into Canada and ecotypes have been have collected seeds from local switchgrass identifi ed in regions from the Atlan- colonies and reproduced them into rela- tic coast to the eastern Rocky Moun- tively uniform strains adapted to particu- tain front. Switchgrass is historically lar locales. These strains, once some bit found in association with several other of uniformity is achieved through artifi cial important native tall-grass prairie selection, are then registered as cultivars plants such as big bluestem, indian- or varieties. This simple breeding program Illustration courtesy of OSU grass, little bluestem, sideoats grama, has created the many switchgrass varieties Forage Information System. eastern gamagrass, and various forbs available today. Page 2 ATTRA Switchgrass as a Bioenergy Crop Upland Varieties Developed by USDA-ARS and Nebraska Agricultural Research Division, Dept. of Agronomy, Univ. of Nebraska. Trailblazer Released 1984. Collections from natural grasslands in Nebraska and Kansas. Adapted to Central Great Plains and adjacent Midwestern states. Developed by Plant Materials Center, NRCS, Manhattan, Kansas. Released 1944. Upland-type switchgrass. Widely Blackwell adapted to Kansas, Oklahoma, southern Nebraska, and northern Texas in areas with 20 inches or more of annual precipitation. Plant Materials Center, NRCS in cooperation with the Missouri AES. Released 1973. Tolerant to fl ooding. Adapted Cave-in-Rock to Midwest. Pathfi nder Selected at Nebraska AES, Lincoln, ARS cooperating. Released 1967. Winter-hardy, late maturing. Selected at Oklahoma AES, Stillwater, ARS cooperating. Released 1955. Forage yield under irrigation outstanding Caddo for native grass; recovers well after mowing. Lowland Varieties Developed by Texas Agricultural Experiment Station and NRCS, Knox City, Texas. Released 1978. A premier Alamo lowland variety, heavy yields especially in the south. Developed at Kansas AES and ARS, Manhattan. Released 1963. Developed for soil conservation in poorly drained Kanlow or frequently fl ooded sites. Source: Oregon State University, 2006. Research studies have determined that select- local Natural Resources Conservation Ser- ing varieties based on location increases the vice (formerly SCS) or Cooperative Extension survivability and productivity of a switch- offi ce for varieties adapted to your area. grass stand. Parrish and Fike (2005) have found a “strong correlation between latitude Establishment, Management, of origin and yield,” and “the main factor determining adaptation of a cultivar was its and Harvest latitude of origin, with southern cultivars Switchgrass has been successfully estab- having higher yield potentials as they are lished by several well-known methods: moved north.” • conventional tillage and drill planting, Switchgrass varieties should therefore be • no-till planting into crop stubble or chosen based upon ecotype (whether an pasture, including CRP, and upland or lowland variety) and the lati- tude of origin. For instance, a high-yield- • frost seeding. ing southern lowland variety like Alamo can For successful biomass plantings, plant 4 to potentially outproduce upland varieties in 10 pounds of switchgrass seed per acre at more northern latitudes. Check with your a depth of ¼ to ½ inch to obtain a plant Seed Sources Oregon State University’s