1. Switchgrass for Biomass Energy
Rob Mitchell
USDA-ARS
Grain, Forage, and Bioenergy Research Unit
Lincoln, Nebraska

2. Where are We Going? Background Establishment
Production, Harvest and Storage
Switchgrass Production Economics
Switchgrass Energy Production
Land Requirements and Feedstocks
Answer Biorefinery Questions

3. Native to Tallgrass Prairie
Ecologically functions as a monoculture

4. Switchgrass Biomass Energy Current Goals & Research
Tools and Products
Weed control, no-till planting, seed quality
Breeding - Biomass specific cultivars & F1 hybrids, improved conversion, NIRS
Molecular biology, cell walls, conversion & seed quality
C sequestration, entomology
Goals
Full establishment in 1 year with 50% yield
Be at full production (5 t/a) second year
Goal of 10 t/a in Midwest; increase ethanol yield/ton
Fully document environmental benefits

5. Establishing Switchgrass
How do you get from this…
…to this?

6. Switchgrass Establishment Recipe
Is switchgrass feasible for the area?
Suitable for dryland corn = suitable for switchgrass
Plant 2 to 3 weeks either side of optimum corn planting date
Develop a good seedbed
No-till seed into soybean stubble
Clean till and pack to leave a faint footprint
Use high quality certified seed of adapted material
Plant at least 30 PLS per ft2 ¼ to 1/2” deep
Manage weeds ASAP!
Pre-emergent application of 1 qt. of atrazine plus 8 oz of quinclorac/acre
Mow or spray broadleaves with 1-2 qt./a of 2,4-D in summer
Spend money on quality seed & weed control

7. Switchgrass seedling morphology, seedbed firmness, and planting depth
Soft seedbed with packer wheel depression
Seedlings develop adventitious roots at soil surface not at seed.
Planting depth .
} = 1/2”
} = 1/2”
Seed 
Seed < 1/2” deep
First rain fills the depression .
} = 1”
Seed 
The seed is too deep and will have problems emerging

8. Worst-Case Scenario for Switchgrass Establishment
6 October 2006
2.5 tons/acre
5 May 2006
No-till seeded 57 acres into soybean stubble on 5 May 2006
Pre-emergent application of 1 qt. of atrazine plus 8 oz of quinclorac/acre
Received 5 in of rain for the first 90-days after planting (40% of LTA)
Mowed & sprayed with 2 qt./acre of 2,4-D to control broadleaf weeds in July
Produced 2.5 tons/acre near Mead, NE in the establishment year (50% of our yield goal)
Seed quality & weed control are critical to economical switchgrass production

9. Worst-Case Scenario for Switchgrass Establishment
27 September 2007
4 tons/acre
2 tons/acre regrowth
31 July 2007
4 tons/acre

10. Worst-Case Scenario for Switchgrass Establishment
17 October 2008
5-6 tons/acre
~1 ton/acre regrowth
7 August 2008
6 tons/acre
Averaged over 4 tons/acre for the planting year and the first 2 production years

11. Switchgrass Harvest & Storage

12. Switchgrass Harvest & Storage

13. Switchgrass Harvest & Storage
24% DM loss in 12 months
3 or 4 wraps reduces spoilage
Big squares rapidly degrade outside
Chopping reduces density

14. Major Questions for Perennial Herbaceous Bioenergy Crops
Can perennial herbaceous biomass energy crops be produced at a cost which makes their use for biomass energy economically feasible? (Initial goal was to compete with $35/barrel oil.)
Are perennial biomass energy crops net energy positive?
New Question: Are they greenhouse gas neutral or negative?

15. Northern Plains Field Scale Production and Economics Trial
15”-17” Annual Precipitation
On-Farm Production
Trials: acre (6-9 ha) fields
Cooperating farmers paid
to manage fields as biomass
energy crops.
31”-33” Annual Precipitation

16. USDA switchgrass study
10 locations for 5 years
165 acres seeded
Seeded with commercial drills
Dryland sites
Harvested entire field with commercial hay equipment

17. Switchgrass Average Annual Production Costs
Cost Item
$/Acre
$/Ton
Planting
12.74
5.74
Herbicide Applied
12.95
5.84
Fertilizer Applied
15.04
6.78
Harvest
32.65
14.72
Total Operating Costs
73.38
33.08
Land Rent
59.70
26.91
Total Cost
133.08
59.99
Costs are annualized at 10%.
Perrin et al. 2008

18. Previous Switchgrass Producer vs. New Crop Producer
Five Year Average Cumulative Costs
Total costs
$/ton
Costs (no land $)
Experienced (2)
$43.13
$26.42
New crop producer (8)
$69.16
$37.28
Experience helped producers reduce production costs by $10.86/ton during the 5 production years.
Perrin et al. 2008

19. Extension Efforts Will Pay Dividends
Field of Jerry Roitsch near Bristol, South Dakota
5-year average yield of 4.2 tons/acre
Average cost of $38/t including land & labor
Farm gate feedstock cost was $0.48/gal
Based on 80 gallons of ethanol per ton, each big bale equals 50 gallons of ethanol

20. Paramount Herbicide vs. No Paramount in Establishment Year
Five Year Average Cumulative Costs
Total costs
$/ton
Costs (no land $)
Paramount used (4)
$44.06
$28.35
No Paramount (6)
$77.22
$39.62
Applying Paramount in the establishment year reduced production costs by
$11.27/ton for 5 production years, a $124/a return on a $20/a investment.
Perrin et al. 2008

21. Year 1 Harvests vs. No Year 1 Harvest Comparisons
Five Year Average Cumulative Costs
Total costs
$/ton
Costs (no land $)
Year 1 Harvest (3)
$44.22
$27.61
No Year 1 Harvest (7)
$72.41
$38.32
Harvestable yields in the establishment year reduced production costs by
$10.71/ton over the 5 production years.
Perrin et al. 2008

22. On-farm Switchgrass Production in the Great Plains – Energy
Previous models over-estimated the energy inputs for switchgrass production by as much as 2X
Switchgrass produced 13X more energy as ethanol than was required as energy from petroleum
Switchgrass produced 540% more renewable than non-renewable energy consumed on marginal land when properly managed
Switchgrass biofuel production systems are economically feasible, and energetically positive on marginal cropland in the central USA east of the 100th Meridian
Results from ARS & UNL economic study. Manuscript in review.
Schmer et al – Proceedings of the National Academy of Science

23. USDA switchgrass study
10 locations
67 ha seeded
Seeded with commercial drills
Dryland sites
Harvested entire field with commercial hay equipment
Man-made prairies
One location
Small-plots
Hand-seeded
Irrigated during establishment
Hand-weeded
Hand-harvested - 10cm wide strips

24. Managed switchgrass produced 97% more ethanol yield than man-made prairies
USDA study
Tilman et al., 2006
Higher yielding farms, a result of following best management practices produced 140% more ethanol than man-made prairies. Switchgrass managed as a bioenergy crop had similar ethanol yields as statewide corn grain yields from Nebraska, South Dakota, and North Dakota. Caution should be made in making direct ethanol yield comparisons with cellulosic sources and corn grain at present because corn grain conversion technology is mature while cellulosic conversion efficiency technology is a predicted value. However, mean corn grain yield is based on irrigated and rain-fed fields on both marginal and fertile soils. Switchgrass will likely be established on rain-fed, marginal soils where row crop yields are generally lower and more variable than crop yields on irrigated or rain-fed, fertile soils. Even with a more conservative cellulosic conversion value, switchgrass from this study is much closer to current corn grain ethanol yields than man-made prairies for this geographic region.

25. What about soil carbon?

26. Switchgrass grown for bioenergy: Soil carbon storage in 5 years: 0-30 cm

27. Switchgrass Soil Carbon Sequestration when grown and managed as a biomass energy crop
Field near Douglas, Nebraska
C storage for field at left:
- 1 Mg SOC/ha/y in the top 30 cm of soil
- 3.7 Mg SOC/ha/y in the top 120 cm of soil
Liebig et al (in press)

28. Grass to crops – what happens to the soil carbon?
Searchinger et al, Science 2008 – sequestered carbon from perennial bioenergy crops is lost due to plowing and crop production.
Fact: plowing is not necessary and not recommended. Too expensive and sod-seeding is easier.
What happens to sequestered C under no-till farming?
Mitchell et al., Renovating pastures with glyphosate tolerant soybeans. Online. Forage and Grazinglands doi: /FG BR.
Soybeans in big bluestem sod
Soybeans in indiangrass sod
Soybeans in fescue
and bluegrass sod

29. Change in soil C – bromegrass sod to no-till corn: 10-30 cm for 6 years. Mead, NE
Data from R. Follett et al., in review.

30. Switchgrass for Bioenergy Economics and Environmental Issues
Switchgrass grown for biomass energy is net energy positive
Evidence is accumulating that indicates switchgrass is greenhouse gas neutral or negative (that is good!)
Switchgrass has wildlife & other benefits
Switchgrass fits the landscape and can be profitable

31. Long-term Study of Corn & Switchgrass Mead, NE
10-year experiment established in 1998 on marginal site in eastern NE
In 2000, corn plots were split & 50% of stover removed on half of plots
Evaluate PV & no-till corn on marginal sites for:
Corn stover removal effects on yield
Response to applied N
Ethanol Production
C sequestration
Switchgrass competition
Sustainability of PV harvest & corn stover removal
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

32. Effect of 50% stover removal on corn grain yields in eastern NE fertilized with 120 kg N/ha. Mean Yields in kg/ha for first 5 years.
Varvel et al Biomass & Bioenergy.

33. Removing ½ of stover reduced grain yield by 7.2%
½ stover removed
- 7.2% grain
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

34. Removing ½ of stover reduced biomass yield by 5%
½ stover removed
- 5% biomass
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

35. Switchgrass Harvested Post Frost was Greater than August* * * *
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

36. Switchgrass Biomass Increased as N Increased
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

37. Corn Biomass was Greater than Switchgrass in August
½ stover removed
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

38. Corn Biomass was Similar to Switchgrass Post Frost
½ stover removed
Cooperative work of ARS Lincoln, ARS Ft. Collins – Ron Follett, and USDA-NRCS National Soils Lab (John Kimble).

39. In an 84-month period, 62 months (74%) were in drought
Seeding year

40. When Should Switchgrass be Harvested?
Switchgrass biomass curve developed from first growth ‘Cave-in-Rock’ switchgrass harvested at 7-day intervals from 5 production environments in August, September, October, and November in 2004, 2005, 2006, and 2007 at Mead, NE.

41. Where Are We Going? Conventional Breeding Progress Yield Trial Mead, NE 2003-2005
Cultivar
Year released
Biomass yield -Ton/a
(Mg/ha)
IVDMD
(%) (mature)
Trailblazer
1984
6.3 (14.1)
52.5
Shawnee
1995
6.5 (14.5)
54.8
NE 2000C1
In seed increase
7.4 (16.6)
53.8
NE Late YD C4
7.0 (15.7)
55.2

42. Hybrid Switchgrass Strain Yield Tons/A (Mg/ha) Kanlow & Summer F1’s
9.4 (21)
Kanlow
7.1 (16)
Summer
6.1 (14)
Vogel & Mitchell, Crop Sci. 2008, In press.
Improved hybrid cultivars with modified cell walls could improve ethanol yields & reduce costs.

43. Forage-type Switchgrass
High-input low-diversity polycultures, currently-available switchgrass, and hybrid switchgrass are feasible feedstocks
Mixture
Yield T/A (Mg/ha)
SN40, PV20, BC40
6.9 (15.5)
AG40, SN20, BC40
6.7 (15.1)
AG20, SN60, PV20
AG40, SN40, PV20
Forage-type Switchgrass
5.1 (11.4)
Hybrid Switchgrass
9.4 (21.2)

44. Biorefinery Investor Questions
How soon can switchgrass be supplied to the biorefinery?
Can adequate biomass be produced and delivered to the biorefinery in a timely manner?
Is production system information available, verified and sustainable?
Bottom Line: Can the area provide a reliable & affordable feedstock supply for the long-term?

45. Question 1
How soon can switchgrass be supplied to the biorefinery? Answer: Full scale switchgrass production could occur in as little as 5 years.

46. Large-scale switchgrass production will require a 2-year lead time before initiating biorefinery construction, assuming Foundation Seed is available for planting Certified Seed fields.
Year 1
Year 2
Year 3
Year 4
Year 5
Harvest Foundation Seed
# PLS/a
Plant Certified Seed -
2 # PLS/acre
Harvest Certified Seed
Plant Biomass Fields
4 # PLS/acre
Harvest Biomass Fields
2 tons/acre
4 tons/acre
Biorefinery
Begin
Construction
Finish
Full
Production

47. Question 2
Can adequate biomass be produced and delivered to the biorefinery in a timely manner? Answer: Using the above seed production timeline, adequate biomass can be produced and delivered to the biorefinery in as little as 5 years.

48. Potential dry matter (DM) yield for herbaceous perennial feedstocks in the Great Plains and Midwest. A 50-million gallon cellulosic ethanol plant will require 625,000 tons of feedstock per year, assuming 80 gallons of ethanol are produced per DM ton.
Feedstock
Yield, DM tons/acre
Acres needed to grow 625,000 DM tons/year
Percent of land in 25-mile radius
LIHD1
1.75
357,000 28
Shawnee switchgrass2 5
125,000 10
Corn
150 bu/acre
111,111
8.8
Bioenergy switchgrass3
7.4
84,460
6.6
Hybrid switchgrass4
9.4
66,489
5.3
1Low-input, high-diversity mixtures (Tilman et al. 2006).
2Upland forage-type switchgrass cultivar released in 1995.
3Lowland Bioenergy-specific switchgrass in the cultivar release process.
4F1 hybrid of Summer and Kanlow switchgrass cultivars that will likely reach field-scale production in 10 years (Vogel and Mitchell 2008).

49. Question 3
Is production system information available, verified and sustainable? Answer: Switchgrass has been grown and managed since the 1930’s. Based on more than 70 years of research, switchgrass production is feasible, verified, and sustainable.

50. Question 4
Can the area provide a reliable & affordable feedstock supply for the long-term? Answer: Switchgrass can provide a reliable and affordable feedstock supply for many areas in the Central and Northern Great Plains, but the preferred feedstock will vary by locations within agro-ecoregions.

51. Where will Cellulosic Ethanol Plants Fit?
A 50-million gallon Ethanol Plant Will Require:
125,000 acres of switchgrass assuming 5 tons/acre and 80 gallons of ethanol/ton of switchgrass.
The Upper Big Blue NRD has 1.83 million acres, 1 million irrigated acres, and 4,600 center pivots. This NRD could grow 128,800 acres of switchgrass in pivot corners alone.
Has 4 existing corn ethanol plants and others under construction or in various planning stages.
25-mile radius

52. Conclusions There is no one-size-fits-all bioenergy system.
Based on nearly 20 years of bioenergy research, we can grow switchgrass in the central USA and be near 50% full production 5 months after seeding and near full production 15 months after seeding.
Switchgrass will not displace corn on prime cropland.
Switchgrass is productive on marginal land when properly managed.

53. Conclusions
Switchgrass biofuel production systems are economically feasible on marginal cropland in the central USA east of the 100th Meridian.
Properly managed switchgrass and warm-season grass mixtures will provide adequate feedstock supply for efficient transport.
The green revolution was successful because of improved genetics and agronomics. Production of sustainable green energy will likewise depend on improved genetics and agronomics.

54. Questions?

55. U.S. Average Regular Pump Price in 2008 was $3.29/gallon
$3.02
$2.13
$1.29
U.S. Average Regular Pump Price in 2008 was $3.29/gallon