Location: Wheat, Sorghum and Forage Research2016 Annual Report
The overall objectives of this continuing long-term project are to develop improved perennial grasses, management practices, and technologies for use in grazing lands and biomass energy production systems in the central USA. Over the next five years, the following specific objectives will be addressed. (1) Develop best management practices for Midwest and central Great Plains perennial grass, mixed grass, and grass-legume pastures to increase livestock production, provide biomass feedstocks for bioenergy production, and maintain ecosystem services; (2) Develop new cool- and warm-season grass cultivars and native legume germplasm for Midwest and Great Plains growing conditions; and (3) Identify biomass characteristics that impact conversion efficiency to liquid fuels. Utilize this information to develop improved breeding criteria and improved management practices.
Improved perennial grasses and legumes and associated management practices will be developed for use in the Central Great Plains and Midwest for bioenergy production and grazing when grown on land that is unsuitable or marginal for grain crop production. Perennial plant breeding technologies will be used to develop the improved cultivars. Improved management methods will be developed to fully utilize the genetic potential of the new cultivars by enhancing establishment, yields, and utilization by livestock, and all aspects of biomass energy crop production. Basic molecular biology and biochemistry/physiology information will be developed that will improve the breeding and management products. The project is a continuation of a long-term perennial grass project that has plant materials, management, and basic science studies in various stages of development and completion. Research will be conducted on both C3 (cool-season) and C4 (warm-season) grasses because both are needed in the region to maximize the length of the grazing season. Switchgrass, big bluestem, and indiangrass will be the primary C4 species and will be developed for use in both bioenergy and livestock production systems. Smooth and meadow bromegrass and intermediate, tall, and western wheatgrass will be bred for use in cool-season pastures. Native legumes will be enhanced for use with C4 grasses in biomass production systems. Grass technologies from this research when utilized on 6 million hectares in the Midwest could produce biofuels for 15 million cars. Beef production per hectare from pastures with new cultivars and improved management could be improved by 10 to over 25%.
Objective 1: Switchgrass seed dormancy can exceed 90% in newly harvested seed. Dormancy can hinder seedling establishment and limit breeding progress if long time periods are required to break seed dormancy. Bioinformatic analyses are in progress to identify genes that are associated with dormancy in switchgrass seeds. Native perennial warm-season grasses provide quality forage during summer when cool-season grass productivity declines. However, little information is available for producers to know if single-species stands or mixtures provide the best livestock performance. A 4-year warm-season grass grazing trial was completed to compare beef cattle average daily gain and gain per acre for the best commercially-available cultivars of native warm-season grass monocultures and mixtures. Initial results indicate the 5-species mixture has the best livestock performance, followed by the 3-species mixture, followed by the single species stands. Livestock performance has been summarized and forage nutritive value is being summarized for both pure stands and mixtures. This study highlights the importance of plant biodiversity in grazing systems. Switchgrass is the model herbaceous perennial biomass feedstock, but corn stover could provide substantial biomass without significantly altering farm production practices. We have initiated Year 19 of a long-term switchgrass and no-till corn bioenergy study on marginally-productive cropland, the longest-term switchgrass and corn comparative study in existence. This study has been a model for collaboration across multiple USDA-ARS research units. Recently-published data reports that switchgrass root biomass C was nearly 5 times greater and root biomass N was 1.7 times greater than the root biomass for corn. Analysis of nutrient removal by each cropping system is in the final stages of completion. Multi-location field trials of switchgrass, big bluestem, and perennial grass mixtures in NE, IA, IL, IN, MN, and WI are fully established. Plot and field-scale harvests continue. Yield data and quality analysis are expanding our understanding of how perennial grasses will perform on marginally productive sites throughout the Great Plains and Midwest. Preliminary results indicate current establishment practices can reliably produce about 50% of the yield potential of the cultivars by the first killing frost in the planting year and the stands can be near full production in the first full growing season after planting. At the field scale, baled and transported yields averaged across the planting year and the first three production years have been near 5 tons per acre for all feedstocks. Objective 2: Polycross nurseries of advanced experimental strains of one switchgrass and three wheatgrass breeding populations were established in FY16. Selection nurseries of three switchgrass and five bromegrass populations were planted in FY16. Biomass and seed harvests of switchgrass, smooth bromegrass, intermediate wheatgrass, and tall wheatgrass breeding nurseries from previous evaluation years were completed as scheduled. Developing improved switchgrass for grazing and bioenergy requires and understanding of the genetic determinants of winter-survival and re-growth. Analyses were conducted to characterize expressed genes and metabolic pathways in divergent switchgrass plants. Resulting data will be deposited into public databases in FY16, and will be used to target traits and genes in improvement efforts. A model for the metabolic functioning of dormant rhizomes for a northern-adapted switchgrass was developed. Objective 3: Plants were significantly damaged by early winter weather in FY14. Plants were collected during FY15 and evaluated. Families and parent plants were selected and will be collected again in FY16 to verify results.
1. Bioenergy progress made by the Central-East Regional Biomass Research Center. The USDA Regional Biomass Research Centers (RBRCs) were established in 2010 to promote collaboration and reduce repetition among researchers in all aspects of the bioenergy-production continuum. The Central-East RBRC, coordinated by ARS-Lincoln, focuses on perennial grasses, biomass sorghum, and corn stover for lignocellulosic biomass. The Central-East RBRC has released “Liberty” switchgrass, a broadly adapted and high yielding perennial biomass crop suited to the Great Plains and Midwest. Additionally, a suite of other warm-season grasses and associated management practices have been developed. Second generation biofuel feedstocks provide an opportunity to increase the production of transportation fuels from recently fixed plant carbon rather than from fossil fuels. Research has demonstrated that integrating perennial grass feedstocks into current agricultural systems will help reduce nutrient escape from fields to surface and groundwater, reduce groundwater use, reduce greenhouse gas emissions, reduce erosion, increase soil carbon sequestration, and improve wildlife habitat for grassland birds. Perennial warm-season grasses and corn stover are well-suited to the eastern half of the USA and provide opportunities for expanding agricultural operations in the region.
2. Management affects soil carbon and nitrogen in switchgrass and corn managed for bioenergy. Root biomass is seldom measured and is simply represented in models that predict landscape level changes to soil carbon and greenhouse gases. We examined the soil beneath switchgrass and corn to measure root biomass, C, N and soil particulate organic matter C (POMC) in a 9-year rainfed study of N fertilizer rates and harvest management in eastern NE. Switchgrass was harvested once in either August or after frost and no-till corn had either 50% or no stover removed. Switchgrass root biomass C was nearly 5 times greater and root biomass N was 1.7 times greater than the root biomass for corn. The highest N fertilizer rate decreased POMC under both corn and switchgrass, indicating faster decomposition rates with more N fertilizer. Residue removal reduced corn root biomass C by 37% and N by 48% and reduced POMC by 22% compared to no-residue removal. Developing productive bioenergy systems that promote soil health will require balancing fertilization that optimizes aboveground productivity and soil C storage.
This project focuses on the development of perennial grasses and legumes and associated management practices and serves the special target audience of small farmers growing perennial grasses for hay and forage, small grass-fed livestock operations, and native legumes for use by honey-bees and other pollinators.
Rinerson, C.I., Scully, E.D., Palmer, N.A., Donze-Reiner, T., Rabara, R.C., Tripathi, P., Shen, Q.J., Sattler, S.E., Rohila, J.S., Sarath, G., Rushton, P.J. 2015. The WRKY transcription factor family and senescence in switchgrass. Biomed Central (BMC) Genomics. 16:912. doi: 10.1186/s12864-015-2057-4.
Paudell, B., Das, A., Tran, M., Boe, A., Palmer, N.A., Sarath, G., Gonzalez-Hernandez, J.L., Rushton, P.J., Rohila, J.S. 2016. Proteomic responses of switchgrass and prairie cordgrass to senescence. Frontiers in Plant Science. 7:293. doi: 10.3389/fpls.2016.00293.
Anderson, W.F., Sarath, G., Edme, S.J., Casler, M.D., Mitchell, R., Tobias, C.M., Hale, A.L., Sattler, S.E., Knoll, J.E. 2016. Dedicated herbaceous biomass feedstock genetics and development. BioEnergy Research. 9:399-411.
Mitchell, R., Schmer, M.R., Anderson, W.F., Jin, V.L., Balkcom, K.S., Kiniry, J.R., Coffin, A.W., White Jr, P.M. 2016. Dedicated energy crops and crop residues for bioenergy feedstocks in the Central and Eastern U.S.A. BioEnergy Research. 9:384-398.
Stewart, C.E., Follett, R.F., Pruessner, E.G., Varvel, G.E., Vogel, K.P., Mitchell, R.B. 2016. N fertilizer and harvest impacts on bioenergy crop contributions to SOC. GCB Bioenergy. doi:10.1111/gcbb.12326.
Ramstein, G.P., Casler, M.D., Evans, J., Kaeppler, S., Mitchell, R., Vogel, K.P., Buell, C. 2016. Accuracy of genomic prediction in switchgrass (Panicum virgatum L.) improved by accounting for linkage disequilibrium. Genes, Genomes, Genetics 6:1049-1062.
Vogel, K., Mitchell, R., Sarath, G. 2016. Registration of NE Trailblazer C-1, NE Trailblazer C0, NE Trailblazer C2, NE Trailblazer C3, NE Trailblazer C4, and NE Trailblazer C5 Switchgrass Germplasms. Journal of Plant Registrations. 10(2):159-165 doi:10.3198/jpr2015.11.0070crg..
Kibet, L., Blanco, H., Mitchell, R., Schacht, W. 2016. Root biomass and soil carbon response to growing perennial grasses for bioenergy. Energy, Sustainability and Society. 6(1):1-8 doi:10.1186/s13705-015-0065-5.