Switchgrass Best Management Practices for Biofuel Production

Compiled and edited by D.K. Lee and Rob Mitchell University of Illinois, Urbana-Champaign U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), Lincoln, Nebraska Switchgrass Best Management Practices for Biofuel Production Acknowledgment This material is based upon work supported by the U.S. Department of Energy’s Office of Energy Efficiency and Renewable Energy (EERE) under the Bioenergy Technologies Office (BETO) Award Number DE-EE0008521. Disclaimer The Sustainable Agriculture Program, Department of Crop Sciences, University of Illinois Urbana-Champaign, produced the publication in collaboration with the U.S. Department of Agriculture, Agricultural Research Service (USDA-ARS), Lincoln, Nebraska. This report was prepared as an account of work sponsored by an agency of the United States Government. Neither the United States Government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States Government or any agency thereof. The views and opinions of authors expressed herein do not necessarily state or reflect those of the United States Government or any agency thereof. Copyright Copyright© 2025 by the Department of Crop Sciences, University of Illinois Urbana-Champaign, USA 3 Contributors Compiled and edited by: D.K. Lee: Department of Crop Sciences, University of Illinois, UrbanaChampaign, Illinois. Rob Mitchell: U.S. Department of Agriculture (USDA), Agricultural Research Service (ARS), Lincoln, Nebraska. Authors: Arvid Boe: South Dakota State University Calvin Ernst: Ernst Seeds, Meadville, Pennsylvania Colleen Zumpf: Argonne National Laboratory, IL David Archer: United States Department of Agriculture-Agricultural Research Service, Mandan, North Dakota Emily Heaton: University of Illinois, Urbana-Champaign Gevan Behnke: University of Illinois, Urbana-Champaign Daniel Wasonga: University of Illinois, Urbana-Champaign Nictor Namoi: University of Illinois, Urbana-Champaign Muhammad Umer Arshad: University of Illinois, Urbana-Champaign Nicholas Boersma: Iowa State University Tim Rooney: Stark Tech, Williamsville, NY Contents Contents .................................................................................................................... 4 Executive Summary ................................................................................................... 5 Introduction .............................................................................................................. 9 Variety Selection ..................................................................................................... 11 Seed Quality and Seeding Rate ........................................................................... 13 Establishment Stage ................................................................................................ 16 Evaluation of Establishment Success .................................................................. 17 Common Causes of Poor-Stand Establishment ................................................... 20 Weed Control in Switchgrass .............................................................................. 20 Maintenance Stage ................................................................................................. 24 Fertilization ......................................................................................................... 24 Diseases and Pest Management ......................................................................... 25 Harvesting Stage ..................................................................................................... 27 Harvest Timing and Cutting Height ..................................................................... 27 Moisture Content and Drying ............................................................................. 28 Baling ................................................................................................................... 29 Storage ................................................................................................................ 30 Potential Yield ......................................................................................................... 31 Switchgrass Production Cost ................................................................................... 32 Environmental and Ecosystem Services .................................................................. 33 Outlook and Policy Implications .............................................................................. 35 Appendices .............................................................................................................. 37 Bibliography ............................................................................................................ 41 5 Executive Summary witchgrass is a perennial C4 grass native to North America and broadly adaptable across the U.S. Its high productivity, low input requirements, and ability to deliver significant ecosystem services benefits, including carbon sequestration, soil conservation, and wildlife habitat, make it well-suited for cultivation on marginal lands. Achieving the U.S. Department of Energy’s projected potential of 1 billion dry tons of biomass annually by 2050 – with switchgrass contributing up to 230 million tons – will require a transition to large-scale, commercial production 1 . This technical guide was developed to provide decisionmakers with current best management practices (BMPs) for establishing, managing, and harvesting bioenergy switchgrass at scale on marginal lands across the U.S. Midwest and Great Plains. Drawing extensively on previous field research and insights from the five-year 'Next-Generation Feedstocks for the Emerging Bioeconomy' project – funded by the U.S. Department of Energy’s Bioenergy Technologies Office – this guide provides practical strategies for scaling up switchgrass production to meet the demands of the growing bioeconomy. The guide distills researchbased insights into actionable recommendations, organized into the following thematic areas: Agronomic Management Successful large-scale deployment of switchgrass requires optimized management strategies, including: • Variety Selection: Lowland varieties (Kanlow, Independence, Mt. Airy, and Cedar Creek) and a hybrid, Liberty, offer high yield potential in midand southern latitudes. Upland varieties 1 US DOE (2024). “2023 Billion-Ton Report”. https://www.energy.gov/eere/bioenergy/2023-billion-ton-report-assessmentus-renewable-carbon-resources S (Shawnee, Cave-In-Rock, Sunburst, and Carthage) are better suited for midto northern U.S. latitudes. • Establishment Practices: Switchgrass grows well on a variety of soils, with best results on well-drained, moderately finetextured soils (pH 5.5-7.0). Planting should occur from mid-April to early June, with seeds placed ¼ to ½ inch deep. No-till seeding into soybean stubble is preferred; conventional tillage requires a firm, packed seedbed. Use drills with depth bands and closing wheels; avoid broadcast seeding due to poor depth control. • Weed Control: Weed management strategies should consider previous land use, ground conditions, soil fertility, planting methods, and planting date. A combination of preand postemergence herbicides – including atrazine, quinclorac, and 2,4-D is recommended, particularly during the first two establishment years 2 . • Fertilization: Apply no nitrogen (N) in the establishment year to reduce weed pressure. From year two onward, apply 10-15 lbs (5-7 kg) of N per ton of biomass removed if harvesting after a killing frost. Adjust rates based on soil N and mineralization estimates from soil tests. • Harvest: Switchgrass should be harvested once annually after a killing frost to enhance nutrient translocation and improve feedstock quality. The target stubble height is 4-6 inches, and biomass should be baled with a moisture content below 20% to prevent spoilage. Economic Viability Switchgrass could be more profitable than corn and soybean on marginal lands, with yields around 4.66 tons/acre (10.45 Mg/ha) and the farmgate 2 Consult herbicide labels, regulations, restrictions, and licensing requirements specific to your state prior to application, as rules vary regionally. 7 price of $80/ton. Depending on biomass yield, the annual production costs, including annualized establishment cost, average $138/acre/year ($340/ha/year) in Illinois and $119/acre/year ($294/ha/year) in Iowa with 50 lbs N/acre (56 kg N/ha) fertilization. Profit margins are estimated at $156/acre/year ($385/ha/year) for Independence in Illinois and $142/acre/year ($350/ha/year) for Liberty in Iowa and Nebraska, assuming the farmer owns the land. Advanced bioenergy cultivars show strong economic performance compared to forage-type cultivars. Environmental and Ecosystem Benefits Switchgrass offers substantial ecosystem services: • Carbon Sequestration: Switchgrass increases soil carbon at rates of 1.01-2.8 Mg C/ha/year. Belowground (root) biomass carbon can accumulate up to ~2 Mg C/ha/year of cultivation. • Erosion Control: Switchgrass’s perennial root system stabilizes soil, protecting against wind and water erosion on fragile lands. • Reduced Emissions and Leaching: Switchgrass requires less fertilizer than annual crops, resulting in lower nitrous oxide emissions and up to 80% reduction in nitrate leaching compared to corn in mature stands. • Wildlife Habitat and Pollinator Support: Switchgrass fields provide critical spring and summer habitat for grassland birds and pollinators, supporting species such as the Common Yellowthroat, Dickcissel, Grasshopper Sparrow, and Sedge Wren more frequently than corn fields. They also support greater insect and pollinator diversity – including bees, flies, beetles, and butterflies – compared to corn fields. Outlook and Policy Implications Switchgrass is a productive, environmentally beneficial, and economically viable option, but its broader adoption is limited by market and infrastructure gaps. Policy support is needed to incentivize both farmers and biorefineries by recognizing environmental benefits and ensuring long-term feedstock supply chains. 9 Introduction witchgrass (Panicum virgatum L.) is a perennial warm-season (C4) grass that is native to the tallgrass prairies of North America. It is broadly adapted to regions below 55°N latitude, spanning from Canada to northern Mexico. Historically, switchgrass has grown alongside other key prairie species such as big bluestem, Indiangrass, sideoats grama, little bluestem, eastern gamagrass, and various forbs (e.g., sunflowers, gayfeather, prairie clover, and prairie coneflower). As the U.S. advances its renewable bioeconomy, the inherent traits and well-documented research history of switchgrass make it highly suitable for large-scale feedstock production across diverse agro-ecoregions. Its appeal as a bioenergy crop stems from its proven long-term (>10 years) productivity in multiple environments, adaptability to marginal cropland, low water and nutrient requirements, ease of establishment and management, compatibility with conventional haying equipment, high biomass yields, and a favorable chemical profile suitable for conversion technologies. Switchgrass offers multiple environmental benefits, including soil carbon sequestration, reduced nutrient losses and soil erosion, and mitigation of greenhouse gas emissions. In line with national energy goals, the U.S. Department of Energy (US DOE), in collaboration with other federal agencies, has set targets to produce 3 billion gallons of sustainable aviation fuel (SAF) annually by 2030 and 35 billion gallons by 2050 3 . Meeting the 2050 target will require 400 biorefineries processing 1 billion dry tons of biomass and/or gaseous carbon dioxide feedstock annually. About 345 million of the 1‑billion dry‑ton biomass annual supply is 3 US DOE (2022). “Sustainable Aviation Fuel Grand Challenge”. https://www.energy.gov/eere/bioenergy/sustainable-aviation-fuel-grandchallenge S Establishment Stage witchgrass performs well across a wide range of soil and landscape conditions. Most fields previously used for annual row crops are generally suitable for switchgrass establishment. Productivity is highest on mediumto high-fertility soils that are moderately fine textured, well-drained to moderately well-drained, and have a pH of 5.5 to 7.0. In the Great Plains and Midwest, the optimal time to plant switchgrass is in the spring, typically from mid-April to early June, ranging from two to three weeks before to two to three weeks after the local corn planting date. When soil moisture and temperature are optimal, switchgrass seedling emergence can begin as early as three days after planting and may be complete within 21 days. However, due to the relatively small seed size compared to annual crops, emergence may be slow, and it is not uncommon for it to appear delayed, with minimal visible growth even 30 days after planting under suboptimal environmental conditions. Due to their small size and panicoid characteristics (subcoleoptile elongation during germination), switchgrass seeds should be planted no deeper than ¼ to ½ inch. Planting deeper than ½ inch can lead to poor establishment, as seedlings may fail to emerge and experience delayed adventitious root development. Switchgrass may be established using either no-till or conventional tillage practices. No-till planting into soybean (Glycine max) stubble is highly effective. Therefore, growing soybeans the year prior to switchgrass establishment is highly recommended. Seeding into corn (Zea mays) or sorghum (Sorghum bicolor) stubble may require residue removal, S Figure 1. Switchgrass planting in early May with a John Deere 750 drill. 17 disking, and packing to develop a firm seedbed. No-till planting offers several benefits, including soil moisture conservation, reduced erosion, and lower fuel, labor, and time requirements. Another advantage of no-till switchgrass seeding is reduced soil disturbance, which helps minimize erosion and can lower weed pressure. For conventional tillage, the seedbed should be packed firmly – firm enough that walking on it leaves only a faint footprint – to ensure good seed-to-soil contact. Loose, uneven, fluffy, or cloddy seedbeds can result in poor stands or complete establishment failure. A drill equipped with depth bands and closing wheels is best for both no-till and conventionally tilled fields (Fig. 1). Native grass drills, no-till drills, or conventional small grain drills may be used if seeding depth and rate are well-controlled. Grain drills and broadcast seeding are generally ineffective and not recommended. Evaluation of Establishment Success Successfully establishing a stand is necessary for a profitable switchgrass production system. The establishment success is evaluated using a frequency grid, often within 42 to 70 days after planting or when grass seedlings are easy to see and have 3 to 4 leaves. The frequency grid (Fig. 2) is a metal frame or rigid wire mesh containing 25 cells (5 x 5). Each cell measures 6 in x 6 in. To determine seeding success: 1. Place the grid either systematically (for smaller plots) or randomly (for larger plots) within the seeded area and count how many of the 25 cells contain at least 1 seeded plant (presence = 1, absence = 0) (Fig. 3). Switchgrass seedlings can be identified by their Figure 2. Switchgrass stand counts monitoring early growth under field conditions. smooth texture and a distinctive purplish coloration on the lower portion of the stem. 2. Flip the grid forward and repeat counts 3 more times at adjacent spots. This gives you 4 placements × 25 cells = 100 total cells sampled. 3. Sum all cells that had at least 1 seeded plant out of the 100 total cells. 4. The total “Presence” cell count out of 100 total cells is the percent frequency of grass seedlings (Equation 4). For example, a count of 50 is interpreted as a stand of 50%. Equation 4: Calculating % Seeding Presence The percent frequency of occurrence can be multiplied by 0.04 to obtain a conservative estimate of plant density/ft2. As a general rule, a minimum of four sampling locations per acre should be assessed to obtain a reliable estimate of establishment success. A stand frequency of 50% or greater (two or more switchgrass plants/ft2) indicates a successful stand, whereas stand frequency between 25 and 50% is marginal to adequate, and stands with less than 25% frequency indicate a partial stand and may need to be reseeded. In a study conducted across five locations in Illinois, Iowa, Nebraska, and South Dakota, switchgrass fields showed a stand frequency of 40% or greater and provided successful stands for bioenergy production. % 𝑠𝑒𝑒𝑑𝑖𝑛𝑔 𝑝𝑟𝑒𝑠𝑒𝑛𝑐𝑒 = 𝑁𝑢𝑚𝑏𝑒𝑟 𝑜𝑓 𝑐𝑒𝑙𝑙𝑠 𝑤𝑖𝑡ℎ ≥1 𝑝𝑙𝑎𝑛𝑡 100 × 100 𝐷𝑒𝑛𝑠𝑖𝑡𝑦 (𝑝𝑙𝑎𝑛𝑡𝑠 𝑓𝑡2 ⁄)= % 𝑠𝑒𝑒𝑑𝑖𝑛𝑔 𝑝𝑟𝑒𝑠𝑒𝑛𝑐𝑒 × 0.04 19 Figure 3. Frequency grid used to assess switchgrass stand success. Red dots indicate grids with switchgrass seedlings. Good stand (left) with a seedling frequency of 88% (based on four grid placements), and poor stand (right) with a seedling frequency of 28%. Assessments may need to be conducted at multiple time points during the establishment phase, such as shortly after seedling emergence, at the end of the establishment year, or during spring green-up in the following year. If switchgrass yield declines over consecutive growing seasons or drops by more than 30% from expected levels under favorable conditions and proper management, re-establishment of the stand may be warranted. The goal for the seeding year is to achieve uniform and successful establishment, followed by a post-frost biomass harvest equal to approximately 50% of the cultivar’s full yield potential, which is typically achieved by the second to third growing season after planting. Before proceeding, an evaluation of winter survival, soil conditions (including drainage, fertility, and pH), and management practices should be conducted to identify the underlying causes of stand decline. Common Causes of Poor-Stand Establishment Several factors can contribute to stand failure in switchgrass, with weed competition – particularly from grassy weeds – being the most common cause. Such competition can delay optimal switchgrass production by one or more years. Other common causes of poor switchgrass stand establishment include: ▪ Poorly prepared seedbed – Seedbed too loose for good seed-to-soil contact and planting depth control. ▪ High seed dormancy – Dormant seeds result in uneven germination and establishment across rows. ▪ Lack of rainfall post-planting – Even when seedlings emerge, prolonged drought can cause seedling mortality. ▪ Frost heaving – Freeze-thaw cycles can push seedlings out of the soil, exposing roots and leading to desiccation. ▪ Herbicide damage – Injury to young seedlings from preor postemergent herbicides can reduce stand density or cause seedling death. ▪ Mowing too closely during the seeding year – Cutting too low can remove the apical meristem, killing young seedlings. Weed Control in Switchgrass Establishing and maintaining a productive stand of switchgrass requires a clear weed management plan (Fig. 4), especially during the first year. Weeds compete with switchgrass for sunlight, water, and nutrients, potentially leading to reduced stands or complete Figure 4. No-till planting in May 2021 showing herbicide application. 21 establishment failure. Key considerations include site history, soil fertility, planting date, seeding method, and timely herbicide application. Site History and Herbicide Residue Before planting, assess prior herbicide use on the site. Residual herbicides from past corn or soybean production may hinder switchgrass establishment. Review product labels for “crop rotation intervals” or “replant periods”. Field Conditions and Fertility Wet fields limit spring herbicide application. Apply glyphosate while switchgrass is dormant (early spring or late fall). Avoid fertilization during the first year – high fertility favors fast-growing weeds over young switchgrass seedlings. Planting Method and Timing No-till systems reduce weed pressure by minimizing soil disturbance. Delaying planting until after the first flush of weeds allows for a pre-plant glyphosate application. Uniform seeding depth and density also help switchgrass seedlings out-compete weeds. Weed Management Strategy Most problematic weeds are grasses like crabgrass, foxtails, barnyardgrass, and johnsongrass. Broadleaf weeds are more easily controlled with selective herbicides. A combination of preand postemergent herbicides is most effective. Table 2 summarizes commonly used herbicides and their recommended application stages in switchgrass systems. Recommended Herbicides Note: Herbicide labels, availability, approved uses, and application rules may vary by state; always consult your state’s herbicide regulations before use 5 . Pre-emergent: Atrazine, Simazine, Pendimethalin (only postestablishment) Post-emergent for grasses: Quinclorac (apply before weeds exceed 4–5 inches) Broadleaf control: 2,4-D (economical), Aminopyralid, Clopyralid, Fluroxypyr, Dicamba (apply after 3–4 leaf stage in switchgrass) Table 2. Herbicides used for weed control in switchgrass grown for biofuel production. Herbicide Weeds controlled Stage of application Glyphosate Broadleaves and grasses Burn down before planting or dormant application in spring Atrazine Broadleaves some grasses PRE to weeds and crop Quinclorac Broadleaves and annual grasses PRE or POST when switchgrass is at 3–4 leaf stage Sulfosulfuron Broadleaves, sedges, quackgrass POST when switchgrass is at 3-4 leaf stage Dicamba Broadleaves POST when switchgrass is at 3-4 leaf stage 2,4-D Broadleaves POST when switchgrass is at 3-4 leaf stage Aminopyralid Broadleaves POST when switchgrass is at 3-4 leaf stage Metsulfuron Broadleaves POST when switchgrass is at 3-4 leaf stage Triclopyr Broadleaves Established stand Burnonly 5 Active ingredients are detailed in the Appendix 3 23 Note: Always read and follow label directions. Example Year 1 Herbicide Program: 1. Two weeks before planting: 4 lbs a.i./ac glyphosate + 2 lbs a.i./ac 2,4-D 2. Immediately after planting: 1 lbs a.i./ac Atrazine or Simazine + 8 oz a.i. /ac Quinclorac 3. Post-emergent (grassy weeds < 5 inches): 8 oz a.i./acre Quinclorac 4. Broadleaf control: 2 lbs a.i./acre 2,4-D at post 3-4 leaf stage Example for Established Stands: 1. Before green-up: 4 lbs a.i./acre Glyphosate + 2 lbs a.i./acre Atrazine or Simazine 2. For summer annual grasses: 8 oz a.i./acre Quinclorac 3. For broadleaf weeds: 2 lbs a.i./acre 2,4-D Maintenance Stage Fertilization Switchgrass nutrient requirements are much lower than annual row crops like corn. However, nitrogen (N) is the primary nutrient limiting switchgrass yield and persistence. Nitrogen fertilizer application is not recommended during the planting year because N will encourage weed growth, increase establishment costs, and increase economic risk if the stand fails. Postestablishment year N-management recommendations for switchgrass can be determined based on available soil N, anticipated biomass yield, and the time of switchgrass harvest. N fertilizer should be applied in late spring when the plant begins active growth or when regrowth reaches 6 to 8 inches in height (Fig. 5). Generally, N-fertilizer application rates can be calculated based on N removal by switchgrass biomass. Nitrogen concentration in switchgrass is typically around 1-2% at flowering but may decline to as low as 0.5% after a killing frost due to translocation of N to below-ground organs for overwinter storage. Consequently, if switchgrass is harvested after a killing frost and yields 4.5-5 tons/acre (10-11 Mg/ha) of dry biomass with a crude protein concentration of 4% (equivalent to approximately 0.64% N), the estimated N removal is about 45-50 lb N/acre (50-55 kg N/ha). Based on regional guidelines for the Great Plains and Midwest, a general N fertilizer recommendation is 10-15 lb N/acre (57 kg N/ha) per ton of anticipated biomass yield when harvesting occurs after a killing frost. The N application rate should be adjusted according to soil N levels and estimated N mineralization rates, as determined through soil testing. In newly established switchgrass fields with high Figure 5. Nitrogen fertilization of switchgrass. 25 residual soil N, fertilizer application rates can be significantly reduced during the initial years of production. However, insufficient N inputs over time can lead to a decline in biomass yield, stand vigor, and increased weed pressure. Long-term yield sustainability requires maintaining adequate N levels through appropriately timed and calibrated fertilization strategies. In Illinois, Iowa, and Nebraska, the yields of bioenergy switchgrass cultivars ‘Independence’ and ‘Liberty’ increased with rising N application rates, with optimal yields achieved at 50 lb N/acre. Similarly, in South Dakota, the bioenergy cultivar ‘Carthage’ also reached optimal yields at 50 lb N/acre (~56 kg N/ha). If soil pH is less than 5.0, lime should be applied to raise pH to 6.5 to allow for more efficient utilization of soil nutrients. Adequate levels of phosphorus (P) and potassium (K) will be in the soil profile in most agricultural fields in the Midwest and Great Plains. If warranted by soil tests, P and K should be applied before planting and incorporated into the soil to promote root growth and encourage rapid establishment. The P and K removal rates can vary considerably and are dependent on growing season, yield, timing of harvest, precipitation, and soil quality. One ton of switchgrass removes about 4 lbs P/acre (~4.5 kg/ha) and 40 lbs K/acre (~45 kg/ha). Nutrients removed through biomass harvest will need to be replenished through appropriate fertilization based on soil test recommendations. Comprehensive soil testing should be conducted the year prior to planting to address any major nutrient deficiencies or soil pH imbalances. Particular attention should be given to phosphorus (P) levels, as P is essential for early root development and seedling establishment. Given the deep-rooted nature of switchgrass, soil samples should be collected in 1-ft increments to a depth of 5 ft to accurately assess nutrient availability throughout the rooting zone. Diseases and Pest Management frost in the planting year, and 70-100% of the yield potential by the end of the second year after planting. Fields should be at full production potential by the second or third growing season after planting, depending on rainfall, and should be productive for a decade or more. A long-term study in Nebraska has maintained full production for 25 years with good management. In large-scale switchgrass fields in Illinois, Iowa, Nebraska, and South Dakota, we have observed average biomass yields exceeding 5 tons/acre/year beginning the year after planting. Switchgrass Production Cost An economic study from Illinois shows that switchgrass is a profitable option for landowners with marginal lands. With a dry matter yield of 4.7 tons/acre (10.45 Mg/ha), switchgrass can economically compete with soybeans priced at $80/ton ($88/Mg), and in some locations, with corn at $60/ton ($66/Mg). Production costs vary by region and management but generally fall into three categories: establishment, maintenance, and harvest. Establishment costs include land preparation, seeding, and drilling; maintenance involves herbicides, N fertilizer, and application; while harvest costs cover swathing, raking, and baling. Tillage costs apply only in the establishment year and are eliminated under no-till systems. Herbicide costs are typically limited to the first two years, while N fertilizer is applied starting in year two, with costs dependent on the source and rate. Machinery expenses are influenced by equipment type, labor and fuel prices, field size, and location. Baling costs, usually charged per bale, are generally lower for round bales than square bales and tend to rise with increased biomass. A recent five-year techno-economic analysis across Illinois, Iowa, Nebraska, and South Dakota confirmed the economic advantage of improved bioenergy cultivars (Independence, Liberty and Carthage) over 33 the traditional forage types. In Illinois, the Independence cultivar fertilized with 50 lb N/acre (56 kg N/ha) had an average production cost of ~$138/acre/year ($340/ha/year) and yielded the highest profit margin of ~$156/acre/year ($385/ha/year), especially in USDA Plant Hardiness Zone (PHZ) 6a (Urbana, IL). In Iowa, Liberty under the same N rate showed a production cost of ~$119/acre/yr ($294/ha/year) and a profit margin of ~$142/acre/year ($350/ha/year), particularly in PHZ 5b (Madrid, IA, and Ithaca, NE). These trends suggest the broader applicability of cultivar-specific profitability across similar climatic zones. Environmental and Ecosystem Services There are numerous environmental benefits to growing switchgrass. The perennial root system of switchgrass provides three important ecosystem services: protecting soil from wind and water erosion by stabilizing fragile soils, intercepting nutrients, thereby reducing nitrate-N leaching, and sequestering C in the soil profile. Switchgrass contributes to carbon sequestration by storing carbon in the soil profile. The rate of soil C accumulation has been estimated at an average of 1.01 Mg C/ha/year, with values reaching up to 2.8 Mg C/ha/year. However, short-term increases in soil carbon are difficult to detect, as measurable changes typically occur over longer timescales. In contrast, belowground biomass offers a more immediate and promising pathway for demonstrating carbon sequestration benefits in the short to near term. Belowground (root) biomass C can accumulate up to 1.75-2 Mg/C/ha/yr within four years of cultivation. Unlike annual crops, switchgrass develops deep root systems that can reach depths of up to 3 meters, facilitating long-term carbon storage in subsoil layers where carbon is less prone to microbial decomposition and loss. A recent study in Illinois revealed that soil N2O emissions were two times lower in switchgrass plots than corn plots. Switchgrass cultivation also enhances soil water quality by reducing nitrate leaching into groundwater. While nitrate losses under switchgrass are initially comparable to corn during the establishment year, they decline significantly over time (at least 80% within three years) as the stand matures and root systems extend deeper into the soil profile, improving nutrient interception and retention. Switchgrass cultivation also contributes to enhanced wildlife habitat quality. In particular, switchgrass fields provide critical breeding and foraging grounds for birds and pollinators during the spring and summer seasons. Findings from our five-year, field-scale trials in Illinois demonstrate that bioenergy switchgrass cultivars can support grassland bird populations, help replace lost habitats, and aid in the recovery of vulnerable species. Species such as the Common Yellowthroat, Dickcissel, Grasshopper Sparrow, and Sedge Wren were observed more frequently in switchgrass plots than in adjacent corn fields. In addition, insect diversity was significantly higher in switchgrass fields compared to continuous corn fields at two Illinois locations (Fig. 16). Four major insect pollinator orders – Hymenoptera (bees), Diptera (flies), Coleoptera (beetles), and Lepidoptera (butterflies and moths) – were present at both sites, indicating that switchgrass can support a robust pollinator community. 35 Figure 12. Acoustic monitor in switchgrass plot at Brighton, IL in June 2020 (a). Sample spectrograms of bird vocalizations recorded (b). Adult male indigo bunting (c) and red-winged blackbird (d), in switchgrass fields in June 2021. To protect nesting birds, management activities such as fertilization and weed control should be minimized during mid to late summer, allowing time for fledglings to become mobile and independent. Harvest timing should also align with wildlife conservation goals. Delaying harvest until after a killing frost helps safeguard grassland-nesting species that depend on switchgrass fields during the spring and summer. In addition, producers may consider partial harvesting or leaving uncut strips to provide dense cover for overwintering wildlife and suitable nesting habitat the following spring. Outlook and Policy Implications Current research demonstrates that switchgrass is a high-yielding, environmentally protective, and economically viable bioenergy crop. Its long-term success depends on the availability of suitable agricultural land and the profitability it offers to farmers. With established best management practices and improved cultivars, sustainable biomass production can benefit both producers and biorefineries. However, limited adoption to date is largely due to inefficiencies in biomass conversion technologies, farmers' reluctance to plant switchgrass without a secure market, and biorefineries’ hesitance to invest without a reliable feedstock supply. To overcome these barriers, policy interventions should offer incentives that reflect both the energy value and environmental services provided by switchgrass, while also fostering the development of stable, long-term feedstock supply chains. Importantly, payments for ecosystem services – such as carbon sequestration, water quality protection, and wildlife habitat enhancement – can further improve the economic attractiveness of switchgrass, compensating farmers for the broader public benefits their land stewardship provides. 37 Appendices Appendix 1: Cultivar factsheets and registration information. • Boe, A., & Ross, J. G. (1998). Registration of ‘Sunburst’ switchgrass. Crop Science, 38(2), 540-540. https://acsess.onlinelibrary.wiley.com/doi/abs/10.2135/cro psci1998.0011183X003800020058x. • Burns, J. C., Godshalk, E. B., & Timothy, D. H. (2008). Registration of ‘BoMaster’ Switchgrass. Journal of Plant Registrations, 2(1), 31–32. https://doi.org/10.3198/jpr2007.02.0094crc. • Burns, J. C., Godshalk, E. B., & Timothy, D. H. (2008b). Registration of ‘Performer’ Switchgrass. Journal of Plant Registrations, 2(1), 29–30. https://doi.org/10.3198/jpr2007.02.0093crc. • Casler, M. D., Vogel, K. P., Mitchell, R. B., & Moore, K. J. (2023). Registration of ‘Cedar Creek’ switchgrass. Journal of Plant Registrations, 17(1), 1–4. https://doi.org/10.1002/plr2.20294. • Casler, M. D., et al. (2023). Espresso switchgrass cultivar release. Journal of Plant Registrations. https://doi.org/10.1002/plr2.20338 • Durling, J. C., Leif, J. W., & Burgdorf, D. W. (2008). Registration of Southlow Michigan germplasm switchgrass. https://www.nrcs.usda.gov/plantmaterials/mipmcrj7805.p df. • Ernst Conservation Seeds. (n.d.). Switchgrass ‘Carthage’ NC ecotype. https://www.ernstseed.com/product/switchgrasscarthage-nc-ecotype/. • Fact Sheet for release of Cave-In-Rock switchgrass (Panicum virgatum L.). USDA-Natural Resources Conservation Service, Elsberry Plant Materials Center, Elsberry, Missouri 63343. Published [November 2011]. https://www.nrcs.usda.gov/plantmaterials/mopmcrb11259. pdf. • High Tide Switchgrass (Panicum virgatum). USDANatural Resources Conservation Service, Cape May Plant Materials Center. Cape May, NJ 08210 Published January, 2014. https://www.nrcs.usda.gov/plantmaterials/njpmcrb12121.p df. • Lee, M., Casler, M. D., & Lee, D. (2024). Registration of ‘Independence’ switchgrass. Journal of Plant Registrations, 18(3), 506–511. https://doi.org/10.1002/plr2.20384. • Newell, L. C. (1968). Registration of Pathfinder switchgrass. https://www.ars.usda.gov/ARSUserFiles/30421000/Hard WinterWheatRegionalNurseryProgram/Cultivarsandgermp lasm/Pathfinder%20switchgrass.pdf. • Release Brochure for ‘Shelter’ switchgrass (Panicum virgatum L.). USDA-Natural Resources Conservation Service, Big Flats Plant Materials Center, Corning, New York 14830. Published [March 2015]. https://www.nrcs.usda.gov/plantmaterials/nypmcrb12507. pdf. • Release Brochure for Blackwell switchgrass (Panicum virgatum ). USDA-Natural Resources Conservation Service, Manhattan PMC. Manhattan, KS 66502. Published: April 2011. https://www.westernnativeseed.com/plant%20guides/blac kwellpg.pdf. • Release Brochure for Carthage switchgrass (Panicum virgatum). 2024. USDA-Natural Resources Conservation Service, Cape May Plant Materials Center. Cape May Court House, NJ. https://www.nrcs.usda.gov/plantmaterials/njpmcrb12120. pdf. • Release brochure for Dacotah switchgrass (Panicum virgatum). USDA Natural Resources Conservation Service, Plant Materials Center. Bismarck, ND. Published January 1990, revised August 2012. https://westernnativeseed.com/plant%20guides/dacotahpg .pdf. • Release brochure for Forestburg switchgrass (Panicum virgatum). USDA Natural Resources Conservation Service, Plant Materials Center. Bismarck, ND. Published August 1988, revised August 2012. https://www.nrcs.usda.gov/plantmaterials/ndpmcrb11304. pdf. 39 • Release Brochure for Southlow Michigan Germplasm switchgrass (Panicum virgatum). USDA-Natural Resources Conservation Service, Rose Lake Plant Materials Center, East Lansing, MI 48823. Published September 2001, April 2014. https://www.nrcs.usda.gov/plantmaterials/mipmcrb12207. pdf. • Rushing, J. B., Baldwin, B. S., & Morrison, J. I. (2024). Registration of ‘Espresso’ lowland switchgrass. Journal of Plant Registrations. https://doi.org/10.1002/plr2.20338 • Vogel, K. P., Haskins, F. A., Gorz, H. J., Anderson, B. A., & Ward, J. K. (1991). Registration of 'Trailblazer' switchgrass. https://www.ars.usda.gov/ARSUserFiles/30421000/Hard WinterWheatRegionalNurseryProgram/Cultivarsandgermp lasm/Trailblazer%20Switchgrass.pdf. • Vogel, K. P., Hopkins, A. A., Moore, K. J., Johnson, K. D., & Carlson, I. T. (1996). Registration of 'Shawnee' switchgrass. https://www.ars.usda.gov/ARSUserFiles/30421000/Hard WinterWheatRegionalNurseryProgram/Cultivarsandgermp lasm/Shawnee%20Switchgrass.pdf. • Vogel, K. P., Jr., Mitchell, R. B., Casler, M. D., & Sarath, G. (2014). Registration of ‘Liberty’ switchgrass. In Crop Science Society of America, Journal of Plant Registrations (pp. 242– 247). https://doi.org/10.3198/jpr2013.12.0076crc. • Wu, Y., and C.M. Taliaferro. 2009. Cimarron switchgrass: A new cultivar for bioenergy feedstock production. ASA, CSSA, and SSSA International Annual Meeting, Pittsburgh, PA. 1– 5 November. ASA and CSSA, Madison, WI. https://a-cs.confex.com/crops/2009am/webprogram/Paper52432.ht ml Appendix 2: Calculating seed amounts on a Pure Live Seed (PLS) basis Appendix 3: Herbicides used in switchgrass production, and their active ingredients Herbicide* Active Ingredient Glyphosate 2-(phosphonomethylamino)acetic acid Atrazine 6-chloro-4-N-ethyl-2-N-propan-2-yl-1,3,5-triazine2,4-diamine Quinclorac 3,7-dichloroquinoline-8-carboxylic acid Sulfosulfuron 1-(4,6-dimethoxypyrimidin-2-yl)-3-(2ethylsulfonylimidazo[1,2-a]pyridin-3-yl)sulfonylurea Dicamba 3,6-dichloro-2-methoxybenzoic acid 2,4-D 2-(2,4-dichlorophenoxy) acetic acid Aminopyralid 4-amino-3,6-dichloropyridine-2-carboxylic acid Metsulfuron 2-[(4-methoxy-6-methyl-1,3,5-triazin-2yl)carbamoylsulfamoyl]benzoic acid Triclopyr 2-(3,5,6-trichloropyridin-2-yl)oxyacetic acid Simazine 6-chloro-2-N,4-N-diethyl-1,3,5-triazine-2,4-diamine Pendimethalin 3,4-dimethyl-2,6-dinitro-N-pentan-3-ylaniline Clopyralid 3,6-dichloropyridine-2-carboxylic acid Fluroxypyr 2-(4-amino-3,5-dichloro-6-fluoropyridin-2yl)oxyacetic acid *Herbicide labels, availability, approved uses, and application rules may vary by state; always consult your state’s herbicide regulations before use. 41 Bibliography Anderson, E. K., Bollero, G. A., Maughan, M. W., Parrish, A. S., Voigt, T. B., & Lee, D. K. (2016). Establishing switchgrass with corn to improve net economic returns. Agronomy Journal, 108(1–8). Arshad, M. U., Archer, D., Wasonga, D., Namoi, N., Boe, A., Mitchell, R., Heaton, E., Khanna, M., & Lee, D. (2025). Comparative economic analysis between bioenergy and forage types of switchgrass for sustainable biofuel feedstock production: A DEA and cost-benefit analysis approach. GCB Bioenergy. https://doi.org/10.1111/gcbb.70020 Association of Official Seed Analysts. (2010a). AOSA rules for testing seeds. AOSA, Ithaca, NY. Association of Official Seed Analysts. (2010b). Tetrazolium testing handbook. AOSA, Ithaca, NY. eXtension Farm Energy. (n.d.). Switchgrass (Panicum virgatum) for biofuel production. https://farmenergy.extension.org/switchgrass-panicum-virgatum-for-biofuelproduction/. Google Patents. (2012). Cimarron switchgrass cultivar. U.S. Patent No. US8278500B2. https://patents.google.com/patent/US8278500B2 LaGory, K. E., Cacho, J. F., Zumpf, C. R., Lee, D., Feinstein, J., DeMatties, D., Walston, L. J., Namoi, N., & Negri, M. C. (2024). Bird species use of bioenergy croplands in Illinois, USA—Can advanced switchgrass cultivars provide suitable habitats for breeding grassland birds? Sustainability, 16(11), 4807. https://doi.org/10.3390/su16114807. Lee, D. K., Doolittle, J. J., & Owens, V. N. (2007). Soil carbon dioxide fluxes in established switchgrass land managed for biomass production. Soil Biology & Biochemistry, 39, 178–186.