Location: Wheat, Sorghum and Forage Research
2024 Annual Report
Objectives
1. Develop best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation’s natural resources. (NP215 1A, 2C, 4B, 4C)
2. Develop new forage and biomass germplasm and cultivars for central U.S. growing conditions. (NP215 1A, 2C)
3. Identify molecular, biochemical and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. (NP215 1A, 2C)
Approach
Project objectives are to develop best management practices for annual and perennial grasses for livestock production, provide feedstocks for bioenergy, develop new forage and biomass cultivars for the central U.S., and identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production and complement breeding and management research. Perennial grass breeding techniques will be refined to design improved cultivars. Improved management methods will be developed to fully utilize the genetic potential of new cultivars by enhancing establishment, yield, and utilization by livestock and by the bioenergy industry. Molecular biology and biochemistry/physiology information will be utilized to improve breeding and management products. The project is a continuation of a long-term perennial grass research program with plant materials, management, and related studies in various stages of development and completion. Research will be conducted on C3 (cool-season) and C4 (warm-season) perennial grasses, and C3 annual grasses. All are needed to maximize the length of the growing season and more fully utilize available land. Switchgrass, big bluestem, and indiangrass are the primary C4 species being evaluated for use in livestock and/or bioenergy production systems. Triticale, a winter annual, will be developed for forage/cover crop use as a double-crop option with early spring grazing and improved soil conservation. New technologies from this research, when utilized on 6 million hectares in the Midwest, could produce biofuels for 15 million cars, increase beef production per hectare by 10%, and increase early spring forage production by 6 million animal unit months.
Applying N fertilizer in the planting year for perennial grasses like switchgrass, big bluestem, and Indiangrass is not well studied and is poorly understood. We will evaluate the interaction of seeding rate, N rate, and N formulation on switchgrass establishment and planting year yield. Although N fertilization on established switchgrass has been studied broadly, little research has been conducted to determine the role of N formulation and application timing. For studies on established stands, we will evaluate the effects of N rate and N formulation (granular vs. foliar-applied) applied at three different growth stages on subsequent switchgrass yield and composition. These studies will serve as baselines and will be expanded to different species and cultivars.
Progress Report
During the 5-year project, the following specific objectives were addressed. (1) Develop best management practices for annual and perennial grasses to increase livestock production, provide biomass feedstocks for bioenergy, and preserve and maintain the nation’s natural resources; (2) Develop new forage and biomass germplasm and cultivars for central U.S. growing conditions; and (3) Identify molecular, biochemical, and plant characteristics that impact livestock and bioenergy production to develop improved breeding criteria and improved management practices. Despite the COVID pandemic and limited precipitation in 2021 and 2022, progress was significant and milestones were met.
For Objective 1, best management practices for annual and perennial grasses were improved to provide biomass feedstocks for bioenergy and preserve and maintain the nation’s natural resources. In the first 16 years of a long-term project, switchgrass systems mitigated greenhouse gas emissions (GHG) emissions during the feedstock production phase compared to GHG-neutral continuous corn under conservation management. Increased soil organic carbon was the major GHG sink in all feedstock systems, but net agronomic GHG outcomes hinged on soil nitrous oxide emissions controlled by nitrogen (N) fertilizer rate. In a five-year study, soil organic carbon, total soil nitrogen, and biomass were evaluated for native perennial warm-season grasses with different N fertilizer rates compared to no-till continuous corn. Soil organic carbon and total soil nitrogen were unchanged over time under either the warm-season grasses or corn. However, soil organic carbon and total soil nitrogen were generally greater in the low-diversity mixture compared to big bluestem. The effect of N fertilizer on warm-season grass biomass was inconsistent. Biomass was generally greater in the low-diversity mixture after the first harvest year. Growing native perennial grasses on marginal cropland can maintain soil organic carbon and soil nitrogen stocks while providing biomass for energy production or in integrated livestock systems, benefiting farmers, the bioenergy industry, and the nation’s natural resources. New near infrared reflectance spectroscopy (NIR) evaluation techniques using hand-held instruments improved our ability to rapidly and inexpensively evaluate forage and biomass feedstock traits.
For Objective 2, perennial grass breeding techniques were refined to design improved cultivars and germplasm for forage and bioenergy. Different ways of analyzing genetic data from a switchgrass breeding population under improvement for bioenergy were evaluated. Selecting for biomass yield, ethanol yield, lignin content, and disease resistance using all generations and integrating the pedigree was improved and provided greater accuracy than the traditional one-generation analysis with no pedigree used by switchgrass breeders. The value of accuracy is directly proportional to predicting and making greater progress from breeding and selection. A selection index incorporating all four traits (biomass yield, ethanol yield, lignin content, and disease resistance) captures the positive relationships between biomass yield, lignin content, and disease resistance and capitalizes on the negative correlation between lignin content and ethanol yield.
For Objective 3, molecular, biochemical and plant characteristics were identified to improve breeding and management practices for forage and bioenergy production. Switchgrass populations had similar and cultivar-specific changes in gene expression. The development of leaf functions and transition to senescence were similar across populations, but Kanlow plants had a much greater number of expressed genes that could be involved in defense against pathogens. This suggests Kanlow plants could provide useful traits for the continued improvement of switchgrass germplasm with improved disease resistance. Further research documented common and uniquely different proteins during the progression of rust infection in the moderately resistant cultivar Kanlow as compared to the rust-susceptible cultivar Summer. This resulted in the detection of significant genetic variation in the switchgrass populations providing opportunities for rust resistance progress to be made by breeding and selection. This study suggested that reducing the incidence of rust in switchgrass is readily attainable through breeding for ultimate deployment of cultivars with durable resistance that potentially benefit farmers, the livestock and bioenergy industries.
Accomplishments
1. Switchgrass is a sustainable and productive biomass feedstock for marginal croplands. Switchgrass is a sustainable and productive biomass feedstock for marginal croplands. Managing annual row crops on marginally productive croplands can be environmentally unsustainable and result in variable economic returns. Incorporating perennial bioenergy feedstocks like switchgrass into marginally productive cropland enhances ecosystem services and climate resiliency while also diversifying the landscape and farm incomes. Long-term economic results indicate switchgrass returns can exceed that of corn by 2.1 times when optimally managed on marginal cropland. The long-term net return for corn was $389 ha–1 fertilized with 120 kg N ha–1, and $815 ha–1 for switchgrass fertilized with 120 kg N ha–1. Additionally, switchgrass is a reliable and sustainable bioenergy feedstock compared to corn as demonstrated by its ability to increase soil organic carbon (SOC) and reduce greenhouse gas (GHG) emissions. The oldest bioenergy- specifc field experiment in North America has demonstrated switchgrass can be economically and environmentally sustainable and productive for more than 25 years on marginal cropland. Although perennial bioenergy systems will not replace annual row crops on prime agricultural land, the environmental and economic benefits on marginal cropland are undeniable.