Location: Wheat, Sorghum and Forage Research2011 Annual Report
1a. Objectives (from AD-416)
The long-term objectives of this project are the development of improved perennial grasses and management practices and technologies for use in biomass energy production systems and grazing land in the mid-continental USA. The focus of the research will be on switchgrass for bioenergy and other warm- and cool-season grasses for grazing lands. Over the next five years, the following specific objectives will be addressed: (1) Provide appropriate plant materials for use in pasture-based livestock systems; (2) Improve the economic viability of forage-livestock systems for the Great Plains and North Central States with improved plant materials and management; (3) Provide improved plant materials for harvested biomass used for bioenergy, bioproducts, and forage; and (4) Develop sustainable production systems for harvested biomass and forage.
1b. Approach (from AD-416)
Improved perennial grass cultivars that are adapted to the Central Great Plains and Midwest states that can be used as biomass energy crops or in grazed grasslands will be developed using conventional and molecular breeding technologies. To fully utilize the genetic potential of the improved cultivars, improved management tools and practices will be developed with emphasis on improving establishment success, forage and biomass yield and quality, utilization by livestock, and all aspects of biomass energy crop production. This project is a continuation of a long-term perennial grass breeding and management program that has plant materials and management practices and tools in various stages of development. In this five-year period, focus will be on development of switchgrass cultivars for use in biomass crop production systems, developing cool- and warm-season grass cultivars for use in grazing systems, and native legume germplasm for potential future use in agriculture using conventional and molecular tools. Management research will focus on improved establishment technology for perennial grasses, enhanced methods for evaluating and renovating degraded grasslands, and improved management practices for switchgrass grown as a biomass energy crop including harvest management. Potential economic and environmental benefits of improved plant germplasm and management technologies will be determined in field and pasture trials.
3. Progress Report
Objective 1a. An improved germination test that combines cold-stratification with chemical treatment was developed that provides rapid and reproducible assessment of seed germination for switchgrass. Negotiations are underway to evaluate this protocol by an independent, certified seed testing facility. Objective 1b. Seed increase of an experimental smooth bromegrass strain was completed for a pending cultivar release. Seed increases of the native legumes, Partridge Pea and Illinois bundleflower, were completed for pending release. Seed increases nurseries of other native legume species were established for future germplasm releases. Objective 2a. Replicated pastures of experimental bromegrass strains were grazed by yearling beef cattle in the spring of 2010. A fall grazing season will be conducted in 2011 followed by an additional two years of grazing. Replicated pastures of pure stands of three native warm-season grasses plus two different native grass mixtures were seeded in spring 2011. Objective 2b. Field evaluation of the grassland assessment tool and other methods of estimating biomass yields in biomass production fields was completed and published. The grassland assessment tool has been compared to other rangeland and pasture assessment tools in field trials and final data summarization is in progress. Objective 3a. Several switchgrass and sorghum genes that participate in lignin biosynthesis have been cloned and their recombinant proteins have been analyzed. Some of the proteins have been used to generate antibodies. Antibodies are being used for developing a protein chip based system to more thoroughly phenotype switchgrass germplasm. Objective 3b. Multi-location field trials of experimental switchgrass strains were completed in cooperation with ARS-Madison. A lowland type with excellent winter survival in the Midwest and high biomass yields was placed in accelerated seed increase in 2010. Seed of germplasms was compiled for pending releases. Objective 4a. Completed evaluation of seed quality tests, including several new project developed tests, for their ability to predict establishment of switchgrass under field conditions. Improved tests are needed to reduce the risk of stand failure during switchgrass establishment. A journal paper is in final review. Objective 4b. The potential variation that can occur in switchgrass biomass composition and potential ethanol yield from farmer fields was determined using switchgrass biomass harvested from 10 fields in Central and Northern Great Plains for a five year period. ARS developed Near Infrared Reflectance Spectroscopy calibrations were used to determine composition and predict ethanol yields. Objective 4c. A long-term switchgrass and corn soil C sequestration study was established in eastern Nebraska 1998. The carbon sequestration results from the first nine years of the study have been summarized. In 2010, one set of switchgrass plots was converted to non-till soybeans. In 2012, these plots will be planted no-till to a lowland, biomass type switchgrass.
1. Improved switchgrass seed quality tests improve establishment and initial biomass yields. The economic viability of growing switchgrass for bioenergy hinges on successful stand establishment the seeding year. ARS researchers in Lincoln, NE, developed an innovative seed lot evaluation test that is based on the number of emerged seedlings per gram of seed in a stress test rather than the percentage of germinated seeds in a germination cabinet. Using this test, rather than the conventional Pure Live Seed method to determine planting rates, resulted in significantly greater switchgrass stands and biomass yields the first harvest year. Basing switchgrass seeding rates on emerged seedlings per gram with an associated stress test will reduce the risks of failure during the stand establishment year due to poor seed quality and will improve biomass yields for the initial harvests.
2. Production environment effects switchgrass biomass quality and ethanol yield. Theoretical ethanol yields were determined from biomass harvested from switchgrass production fields on 10 farms in Nebraska and South and North Dakota for a five year period. Near Infrared Reflectance Spectroscopy (NIRS) calibrations developed by a team of ARS scientists from Lincoln, NE, St. Paul, MN, Peoria, IL, and Madison, WI were used to determine switchgrass composition and quality and predict ethanol yields. Theoretical ethanol yield varied significantly by year and field, with 5 year means ranging from 91 to 103 gallons per ton of biomass. Total theoretical ethanol production ranged from 187 to 394 gallons per acre across fields planted to forage type switchgrass cultivars. Because of the differences in potential liquid fuel yields per ton, cellulosic biorefineries will need to test switchgrass for biomass quality which will be feasible with the ARS NIRS calibrations. Cellulosic biorefineries will need to consider the yearly variation that can occur in biomass production in a region in their business plans.
3. Soil carbon storage benefits of switchgrass and no-till corn grown for energy underestimated. The changes in soil organic carbon during the first nine years of a long-term switchgrass and corn soil carbon sequestration study indicates that all soil carbon changes were positive and that nitrogen fertility rates and harvest management affected the net increase in soil carbon. ARS scientists at Lincoln, NE, and Ft. Collins, CO, demonstrated that both switchgrass and corn sequestered soil organic carbon down to a depth of 5 feet and over 50% of the soil organic carbon was sequestered below the one foot depth, which is the soil depth upon which most previous modeling work is based. Both switchgrass and corn sequestered 0.9 tons of carbon per year with the best management practices. The results demonstrate that previous modeling work on the net benefits of bioenergy crops, which were conducted assuming uniform responses to management and a shallow one foot soil sampling depth for soil carbon, significantly underestimated the soil carbon storage benefits of switchgrass and no-till corn production.
Saathoff, A.J., Tobias, C.M., Sattler, S.E., Haas, E.E., Twigg, P., Sarath, G. 2011. Switchgrass contains two cinnamyl alcohol dehydrogenases involved in lignin formation. BioEnergy Research. 4(2):120-133.