United States 

Department of 

Agriculture

Natural 

Resources 

Conservation 

Service

Plant Materials Center

July 2009

Indiangrass

(Sorghastrum nutans) 

Biomass Trials

North Dakota, South Dakota, and Minnesota
Who We Are

Plants are an important tool for conservation. 

The Bismarck Plant Materials Center (PMC) is part 

of the United States Department of Agriculture, 

Natural Resouces Conservation Service

(USDA, NRCS). It is one of a network of 27 

centers nationwide dedicated to providing 

vegetative solutions to conservation problems. 

The Plant Materials program has been providing 

conservation plant materials and technology 

since 1934.

Contact Us

USDA, NRCS Plant Materials Center

3308 University Drive

Bismarck, ND 58504

Phone: (701)250-4330

Fax: (701)250-4334

http://Plant-Materials.nrcs.usda.gov

Acknowledgements

Cooperators and partners in the warm-season 

grass evaluation trials, together with the USDA, 

NRCS Plant Materials Center at Bismarck, North 

Dakota, have included: the U.S. Department 

of Interior, Fish and Wildlife Service (J. Clark 

Salyer National Wildlife Refuge near Upham, 

North Dakota; the Wetland Management 

District at Fergus Falls, Minnesota; and the 

Karl E. Mundt National Wildlife Refuge near 

Pickstown, South Dakota); the South Dakota 

Department of Agriculture Forestry Division; 

the South Dakota Department of Game, Fish, 

and Parks; the Minnesota Department of Natural 

Resources, Division of Forestry; the U.S. Army 

Corps of Engineers; the USDA, NRCS field and 

area offices and Soil and Water Conservation 

District offices located at Bottineau, North 

Dakota; Fergus Falls, Minnesota; Lake Andes, 

South Dakota; Onida, South Dakota; Rochester, 

Minnesota; and Pierre, South Dakota; the 

Southeastern Minnesota Association of Soil 

and Water Conservation Districts; the Hiawatha 

Valley Resource Conservation and Development 

Area (Minnesota); and the North Central 

Resource Conservation and Development Office 

(South Dakota).

In this photo: 

 Indiangrass seed 

that has been 

debearded. It is 

smooth and flows 

easily through a 

grass drill.
Indiangrass 

(Sorghastrum nutans)

Biomass Trials

North Dakota, South Dakota, and Minnesota

Dwight Tober, Plant Materials Specialist; Nancy Jensen, Agronomist; 

Wayne Duckwitz, Plant Materials Center Manager; 

and Mike Knudson, Assistant Plant Materials Center Manager; 

USDA, Natural Resources Conservation Service, Bismarck, North Dakota

Indiangrass [Sorghastrum nutans (L.) Nash] is a tall, tufted, warm-season perennial grass with short, stout, 

scaly rhizomes. It has also been described as a bunchgrass. It grows to an average height of 3 to 5 feet. 

Inflorescence is a contracted panicle that is golden to reddish tan and softly hairy. The species occurs 

naturally from Canada to Mexico through the eastern and central United States (USDA NRCS 2004). It is 

codominant with big bluestem and switchgrass in tall grass prairies. It grows on a wide range of habitats, 

from prairies to woodlands, savannahs, and scrubland vegetation. In the drier area of its natural range, it 

prefers fertile bottomlands or lowlands where moisture is more available. It can grow in a wide array of soils 

ranging from sandy loam to clay loam. It is used for forage, erosion control and restoration.

Dry matter biomass yields and other plant performance documentation were compiled for Indiangrass 

and six other warm-season grass species from 1982 to 1992 at six sites in North Dakota, South Dakota, 

and Minnesota (Jacobson et al 1986). The effect of seed origin (parentage) on plant performance was 

apparent. Five varieties 

of Indiangrass were 

evaluated with origin 

varying from North 

Dakota to Oklahoma and 

Illinois. Winter injury 

was a problem for the 

more southern varieties 

when grown at the more 

northern locations. When 

winter injury was not an 

issue, the more southern 

seed sources generally 

had higher biomass 

production although stand 

longevity may have been 

impacted. Plant density 

(stand index) was related 

to winter injury and 

biomass yield. Northern Figure 1. Locations of warm-season grass trials in North Dakota, 

South Dakota, and Minnesota

1
seed sources moved more than 200 miles 

southward from their origin generally 

did not perform well, and biomass was 

significantly less than local or more 

southern origin sources. Northern 

varieties required fewer days for seed 

maturity compared to the more southern 

origin seed sources.

Trial Sites

The trial sites were studied in 

cooperation with numerous partners (see 

acknowledgements inside front cover). 

They were located near Upham, North 

Dakota; Fergus Falls, Minnesota; Rochester, Minnesota; Lake Andes, South Dakota; Onida, South Dakota; 

and Fort Pierre, South Dakota (Fig. 1). Soils and precipitation information are included with the tables 

(pages 6-11). Growing seasons at the six locations varied from an average of 110 days at Upham, North 

Dakota, to an average of 150 days at Rochester, Minnesota. Average annual precipitation ranged from 15 to 

30 inches. Seven to nine different species of warm-season grasses were evaluated at each site. Each species 

included two or more varieties or seed sources. Indiangrass is the only species presented in this report.

Methods and Materials

The experimental design was a randomized complete block with three replications for data collection. An 

evaluation array was seeded for demonstration purposes. Plot size varied from 12 to 15 feet in width, and 

from 60 to 100 feet in length. A clean, firm seedbed was prepared by disking, harrowing, and roller packing. 

The plots were seeded using a grass seed drill. Herbicides were used for weed control. Biomass residue was 

removed each spring either by mowing and raking, or burning. No fertilizer was applied.

Data collection at all six locations 

included stand ratings, plant height, 

weed contamination, stand index density, 

phenology, and annual biomass production. 

Only biomass production, stand density, and 

phenology are presented and discussed in 

this report.

Stand index density was determined by 

estimating the number of plants in a 9-inch 

by 16-inch quadrat. Ten quadrats were 

systematically counted near the center line 

of each plot. A density index rating was 

developed. Values ranging from 0 to 40 

plants per square foot were used to estimate 

density for each subsample. 

2

All plots were planted into a clean, firm seedbed
Dry matter yield was documented at all sites beginning the second year following establishment. Biomass 

production was determined by clipping a 2-foot by 10-foot subplot in each plot with a forage harvester. 

Sampling dates were as close as possible to the end of the growing season (first killing frost). The sample 

plots were systematically located within each plot across the treatment and clipped to a stubble height of 

approximately 2 inches. After weighing the large samples, small (100 gram) grab-samples were weighed, 

oven-dried at 60 degrees C for 48 hours, and used for dry matter determinations. Biomass production is 

reported in pounds per acre.

Estimating plant density in 

10 quadrats/plot to determine stand index

The drill was carefully cleaned between 

seeding plots to avoid contamination

3

Harvesting 10-foot by 2-foot strips 

to determine biomass yield
4

Variety/Seed Source Origins (USDA SCS 1994)

Tomahawk

Tomahawk originated from a composite of three seed 

collections made in 1961 from native stands near Ludden, 

North Dakota (Dickey County), Britton, South Dakota 

(Marshall County), and Hecla, South Dakota (Brown 

County). These were selected from a comparison trial at 

the Bismarck PMC for high seed yield and winter survival. 

At northern latitudes, forage production is similar to the 

variety Holt. Seed matures approximately 30 days earlier 

than Holt, 70 days earlier than Oto, and 80 days earlier than 

Osage and Rumsey. Chromosome number is 2n=40. It was 

released cooperatively in 1988 by the USDA-NRCS Plant 

Materials Center, Bismarck, North Dakota; USDA-ARS 

Northern Great Plains Research Laboratory, Mandan, 

North Dakota; and the North Dakota, South Dakota, and 

Minnesota Agricultural Experiment Stations.

Tomahawk Indiangrass

5-year average forage production

0

2000

4000

6000

8000

Upham

Fergus

Falls

Lake

Andes

Onida

Rochester

Ft. Pierre

Location

pounds/acre

Holt

Holt is moderately early maturing; and superior in leafiness 

and yield to early maturing strains from the northern and 

western sandhill region of Nebraska. It originated from 

collections from native prairie ecotypes of the sandhills 

and adjacent areas in the Elkhorn Valley of Holt County in 

northeastern Nebraska. It is typical of Indiangrass ecotypes 

of north central and northeastern Nebraska. It was grown at 

Lincoln, Nebraska, since 1942 and cooperatively released 

in 1960 by the Nebraska Agricultural Experiment Station, 

and the USDA-ARS, University of Nebraska, Lincoln.

Holt Indiangrass

5-year average forage production

0

2000

4000

6000

8000

Upham

Fergus

Falls

Lake

Andes

Onida

Rochester

Ft. Pierre

Location

pounds/acre
5

Oto

Oto matures late in the season with seed harvest at early 

frost in southern Nebraska. It originated from collections 

from natural grasslands of Nebraska and Kansas in 

1953-1954. Fifteen accessions (collections) exhibited 

bright green leaves, brown panicles and late maturity. 

One group of 100 clones was isolated and progeny bred 

true for brown glumed seed. It was developed at the 

Nebraska Agricultural Experiment Station, Lincoln, and 

cooperatively released with USDA-ARS in 1970.

Oto Indiangrass

5-year average forage production

0

2000

4000

6000

8000

Upham

Fergus

Falls

Lake

Andes

Onida

Rochester

Ft. Pierre

Location

pounds/acre

Osage

Osage originated from seed collected in 1953 from eastern 

and central Kansas and Oklahoma. Recurrent selection for 

leafiness, vigor, freedom from rust, and earliness of maturity 

in Kansas was used as the method of development. It was 

released in 1966, cooperatively by Kansas Agricultural 

Experiment Station; Plant Sciences Division, Soil 

Conservation Service; and Plant Science Research Division, 

Agricultural Research Service.

Osage Indiangrass

5-year average forage production

0

2000

4000

6000

8000

Upham

Fergus

Falls

Lake

Andes

Onida

Rochester

Ft. Pierre

Location

pounds/acre

Rumsey

Rumsey is described as having increased seedling growth 

rate, superior forage production, and increased resistance to 

lodging. It flowers late in the growing season. It originated 

from a collection from a native stand in southern Illinois 

(Jefferson County). It was tested and selected at Elsberry, 

Missouri, and was released in 1983 by the USDA-NRCS 

Plant Materials Center at Elsberry in cooperation with the 

Missouri Agricultural Experiment Station.

Rumsey Indiangrass

5-year average forage production

0

2000

4000

6000

8000

Upham

Fergus

Falls

Lake

Andes

Onida

Rochester

Ft. Pierre

Location

pounds/acre
Upham, North Dakota

Average annual precipitation for the 5 years of biomass harvest was near normal. Tomahawk and Holt, the 

two northernmost varieties, had the highest biomass yields in 1983, 1984, and 1985, and had the highest 

5-year averages of 4,156 lbs/ac, and 3,869 lbs/ac, respectively. Tomahawk and Holt also had the highest 

average stand index ratings, 17 and 16 respectively. Oto, Osage, and Rumsey showed signs of moderate 

to severe winter injury the second growing season. Varieties with winter injury tended to rebound due 

to reduced plant populations. Plants were larger and more vigorous in years three through five. There is 

anticipation, however, that additional harvesting or grazing of these varieties would further reduce stands. 

Rumsey had the most winter injury, and was rated lowest for biomass and stand index. Phenology ratings 

were taken in early August, and at that time, Tomahawk already had first seed ripening, compared to Holt 

which was just starting to flower. Oto, Osage and Rumsey were at the vegetative growth stage. The first 

killing frost on this site is often as early as late August. .

Upham, North Dakota (MLRA 55A, north central North Dakota) 

Average Annual Precipitation: 16.08 inches

Soils: Great Bend silty clay loam

6

(pounds/acre) Stand

 Variety Biomass1 Index2 Phenology3

1983 1984 1985 1986 1987 Avg Rank 1982-1984* Early Aug.

 Precip. deviation (0.98) (0.9) (1.63) (-0.09) (-1.23)

 Tomahawk 4918a 2419ab 4410a 5729a 3304a 4156 1 17 6

 Holt 4330a 3190a 4219a 4937a 2668a 3869 2 16 4

 Oto 1695b 1750b 3178ab 4980a 3866a 3094 3 11 1

 Osage 716b 1736b 3610a 3493ab 3725a 2656 4 9 1

Rumsey 538b 588c 1989b 1747b 3852a 1743 5 8 1

Statistical Analyses: Duncan’s New Multiple Range Test, means with same letter are not significantly different (P=.05) 1

Biomass: flail-type forage harvester, 2’ x 10’ strip in each plot clipped to a 2-inch stubble height 2

Stand Index: Estimate of plant density in 10 (1.0 sq ft) quadrats per plot. Full frame=40 3

Phenology (1984): 1=vegetative; 2=jointing; 3=first emergence of inflorescence; 4=first anthesis,10 culms or more;

 5=50% anthesis; 6=first seed ripe; 7=50% seed ripe; 8=seed mature; 9=complete dormancy

* Data is an average from these years

Tomahawk continues to perform well

 10 years after seeding

Severe winter 

injury

 on Osage 

Indiangrass
Fergus Falls, Minnesota

The soils on this site are a well drained loam complex formed in calcareous glacial till. Two years of well 

below normal precipitation in 1983 (-3.96) and 1987 (-7.2) reduced the 5-year average biomass yields. Holt 

had the best average biomass yield of more than 4,000 lbs/ac over the five year period. Stand index ratings 

were similar, with the most northern variety Tomahawk having the highest rating with 20. Rumsey had 

severe winter injury and had the lowest average stand index rating of 4. Tomahawk had ripe seed in early 

September compared to Holt which was at first anthesis, and Oto, Osage, and Rumsey which were still at the 

vegetative growth stage.

Fergus Falls, Minnesota (MLRA 102A, west central Minnesota)

Average Annual Precipitation: 23.52 inches 

Soils: Barnes and Langhei loam

7

(pounds/acre) Stand

 Variety Biomass1 Index2 Phenology3

1983 1984 1985 1986 1987 Avg Rank 1983-1984* Early Sept.

 Precip. deviation (-3.96) (1.54) (.85) (6.23) (-7.2)

 Tomahawk 4566ab 3852a 2234a 2917a 973a 2908 3 20 7

 Holt 5428a 5791a 4562a 3111a 1743a 4127 1 14 4

 Oto 4623ab 3041a 2079a 1028a 818a 2318 5 19 1

 Osage 3834ab 5262a 3300a 1901a 1494a 3158 2 13 1

 Rumsey 1993b 3570a 3844a 1822a 1712a 2588 4 4 1

Statistical Analyses: Duncan’s New Multiple Range Test, means with same letter are not significantly different (P=.05) 1

Biomass: flail-type forage harvester, 2’ x 10’ strip in each plot clipped to a 2-inch stubble height 2

Stand Index: Estimate of plant density in 10 (1.0 sq ft) quadrats per plot. Full frame=40 3

Phenology (1983): 1=vegetative; 2=jointing; 3=first emergence of inflorescence; 4=first anthesis,10 culms or more;

 5=50% anthesis; 6=first seed ripe; 7=50% seed ripe; 8=seed mature; 9=complete dormancy

* Data is an average from these years

The experimental design was a randomized 

complete block at all sites

Holt Indiangrass performed well at Fergus Falls 

and was ranked first in average biomass yield
Lake Andes, South Dakota

Three years of well above average rainfall influenced biomass production at this site. The soils are a fertile 

Agar silt loam. Above average precipitation amounts totaled 12.9 inches (1984), 10.7 inches (1986), and 

3.71 (1987). This was the most southern of the test sites, and the more southern varieties performed best, 

except for Rumsey which again suffered severe winter injury. Rumsey had an initial stand index rating of 

2. It bounced back in years three through five and had comparable biomass yields to the other three southern 

varieties. Stand index ratings were comparable for the other four varieties and ranged from 15 to 22. Oto 

had the highest 5-year average biomass yield of almost 7,000 lbs/ac. Tomahawk was ranked last in biomass 

yield with an average of 3,508 lbs/ac for 5 years. The abundant rainfall in 1986 resulted in biomass yields 

in the 9,000 to 10,000 lbs/ac range for all varieties except Tomahawk which was about half that amount. 

Tomahawk again had the earliest maturity and had mature seed in early September. Holt at this time was 

at 50 percent anthesis compared to Oto, Osage, and Rumsey which were still at the first emergence of 

inflorescence growth stage.

Lake Andes, South Dakota (MLRA 55C, southeast South Dakota)

Average Annual Precipitation: 21.37 inches

Soils: Agar silt loam

8

(pounds/acre) Stand

 Variety Biomass1 Index2 Phenology3

1984 1985 1986 1987 1988 Avg Rank 1984 Early Sept.

 Precip. deviation (12.9) (-.21) (10.7) (3.71) (1.0)

 Tomahawk 2890b 2413b 4824b 2825a 4587a 3508 5 16 8

 Holt 3412b 4021ab 9860ab 4777a 4181a 5250 4 15 5

 Oto 8098a 5828a 10223a 5479a 5063a 6938 1 20 3

 Osage 7097a 6382a 9720ab 4857a 5013a 6614 2 22 3

 Rumsey 3612b 3813ab 9077ab 5539a 5719a 5552 3 2 3

Statistical Analyses: Duncan’s New Multiple Range Test, means with same letter are not significantly different (P=.05) 1

Biomass: flail-type forage harvester, 2’ x 10’ strip in each plot clipped to a 2-inch stubble height 2

Stand Index: Estimate of plant density in 10 (1.0 sq ft) quadrats per plot. Full frame=40 3

Phenology (1984): 1=vegetative; 2=jointing; 3=first emergence of inflorescence; 4=first anthesis,10 culms or more;

 5=50% anthesis; 6=first seed ripe; 7=50% seed ripe; 8=seed mature; 9=complete dormancy

Rumsey had severe winter injury such as this 

the first two years but biomass yield 

was good in years three through five

The more southern varieties

performed better at Lake Andes
Onida, South Dakota

The soil at the site is a Lowry silt loam, which is fertile but droughty. Average annual precipitation was near 

normal for 3 years, considerably above normal in 1986 (5.27 inches), and below normal in 1988 

(-4.07 inches). Holt, Oto, and Osage had similar and the best 5-year average biomass production. Yields 

ranged from 2,402 to 2,800 lbs/ac. Rumsey was last in biomass yield with 861 lbs/ac. It also had winter 

injury resulting in the lowest stand index rating of 8. The other four varieties had similar stand index ratings 

ranging from 19 to 26. Phenology was comparable to the other sites with Tomahawk having mature seed 

in early September, while Holt had first ripe seed, and Oto had inflorescences first emerging. Osage and 

Rumsey were still at the jointing growth stage.

Onida, South Dakota (MLRA 53C, central South Dakota)

Average Annual Precipitation: 17.47 inches

Soils: Lowry silt loam

9

(pounds/acre) Stand

 Variety Biomass1 Index2 Phenology3

1985 1986 1987 1988 1989 Avg Rank 1984-1985* Early Sept.

 Precip. deviation (.13) (5.27) (-1.86) (-4.07) (.33)

 Tomahawk 365a 5127b 2991a 507a 1217a 2041 4 20 8

 Holt 1014a 6183ab 4256a 1333a 1212a 2800 1 26 6

 Oto 1353a 7439a 2753a 520a 457ab 2504 2 23 3

 Osage 869a 6071ab 3644a 943a 483ab 2402 3 19 2

 Rumsey 224a 1477c 1887a 521a 197b 861 5 8 2

Statistical Analyses: Duncan’s New Multiple Range Test, means with same letter are not significantly different (P=.05) 1

Biomass: flail-type forage harvester, 2’ x 10’ strip in each plot clipped to a 2-inch stubble height 2

Stand Index: Estimate of plant density in 10 (1.0 sq ft) quadrats per plot. Full frame=40 3

Phenology (1986): 1=vegetative; 2=jointing; 3=first emergence of inflorescence; 4=first anthesis,10 culms or more;

 5=50% anthesis; 6=first seed ripe; 7=50% seed ripe; 8=seed mature; 9=complete dormancy

* Data is an average from these years

The more southern varieties were taller The maturity difference between Tomahawk (left) 

and Holt (right) is about 30 days
Rochester, Minnesota

The soils are a well drained, rolling silt loam. This site, with 29.58 inches, had the highest average annual 

precipitation of the six test sites. Precipitation was quite variable from year to year. It was below normal in 

1987 (-2.63), 1988 (-8.19), and 1989 (-6.85). Precipitation was substantially above normal in 1990 (14.36), 

and 1991 (7.33). Biomass yield was significantly less than expected on this site for all entries. The droughty 

soils with low fertility may have been a factor. Oto, Osage, and Holt had the highest average five-year yields 

and ranged from 2,509 to 3,034 lbs/ac. Rumsey again had the lowest stand index rating of 4. Oto, Osage, 

and Holt also had the highest 5-year average stand index ratings ranging from 11 to 15. All five varieties 

were reported to have different phenology ratings in early September, ranging from first seed ripe for 

Tomahawk to jointing for Oto.

Rochester, Minnesota (MLRA 105, southeast Minnesota)

Average Annual Precipitation: 29.58 inches

Soils: Mount Carrol silt loam

10

(pounds/acre) Stand

 Variety Biomass1 Index2 Phenology3

 1987 1988 1989 1990 1991 Avg Rank 1985-1987* Early Sept.

 Precip. deviation (-2.63) (-8.19) (-6.85) (14.36) (7.33)

 Tomahawk 2814b 2514a 1764a 2388a 1184a 2133 4 7 6

 Holt 5451ab 1595a 1777a 2454a 1266a 2509 3 13 5

 Oto 9136a 1376a 1552a 2339a 769a 3034 1 15 2

 Osage 8752a 1715a 1462a 1503a 1059a 2898 2 11 3

 Rumsey 3461b 1715a 2914a 1171a 1151a 2082 5 4 4

Statistical Analyses: Duncan’s New Multiple Range Test, means with same letter are not significantly different (P=.05) 1

Biomass: flail-type forage harvester, 2’ x 10’ strip in each plot clipped to a 2-inch stubble height 2

Stand Index: Estimate of plant density in 10 (1.0 sq ft) quadrats per plot. Full frame=40 3

Phenology (1988, 1989): 1=vegetative; 2=jointing; 3=first emergence of inflorescence; 4=first anthesis,10 culms or more;

 5=50% anthesis; 6=first seed ripe; 7=50% seed ripe; 8=seed mature; 9=complete dormancy

* Data is an average from these years

Holt had mature seed in October Osage performed well given its southern origin
Fort Pierre, South Dakota

The soil at the site is Promise clay, which is fertile with low permeability. Infiltration is less than 0.2 inches 

per hour. Three consecutive years (1988, 1989, and 1990) of significantly lower than normal rainfall greatly 

reduced annual and the 5-year average biomass yields. Oto and Osage had the highest 5-year average 

biomass yields of 2,091 lbs/ac and 1,634 lbs/ac, respectively. Tomahawk and Rumsey were ranked last with 

each averaging less than 1,000 lbs/ac. Rumsey also showed signs of winter injury, and had the lowest stand 

index rating of 13. Holt, Oto, and Osage had the highest average stand index ratings ranging from 24 to 31. 

Phenology was comparable to the other sites with Tomahawk maturing first with 50 percent ripe seed in early 

September. Holt was the second most mature and was at 50 percent anthesis compared to the other three 

varieties which were still jointing.

Fort Pierre, South Dakota (MLRA 63A, central South Dakota)

Average Annual Precipitation: 18.08 inches

Soils: Promise clay

11

(pounds/acre) Stand

 Variety Biomass1 Index2 Phenology3

1988 1989 1990 1991 1992 Avg Rank 1986-1987* Early Sept.

 Precip. deviation (-7.3) (-4.77) (-5.74) (.87) (.79)

 Tomahawk 205b 81a 488b 1655a 1494b 785 4 17 7

 Holt 594a 242a 515b 2069a 2991ab 1282 3 25 5

 Oto 238b 214a 2081a 2780a 5142a 2091 1 31 2

 Osage 256b 312a 888b 2050a 4662ab 1634 2 24 2

 Rumsey 607a 376a 729b 549b 0 452 5 13 2

Statistical Analyses: Duncan’s New Multiple Range Test, means with same letter are not significantly different (P=.05) 1

Biomass: flail-type forage harvester, 2’ x 10’ strip in each plot clipped to a 2-inch stubble height 2

Stand Index: Estimate of plant density in 10 (1.0 sq ft) quadrats per plot. Full frame=40 3

Phenology (1990): 1=vegetative; 2=jointing; 3=first emergence of inflorescence; 4=first anthesis,10 culms or more;

 5=50% anthesis; 6=first seed ripe; 7=50% seed ripe; 8=seed mature; 9=complete dormancy

* Data is an average from these years

The plots were burned each spring so only new 

growth was harvested as biomass

Indiangrass yielded the lowest average biomass 

at Fort Pierre on the Promise clay soils
Results and Discussion

Biomass yields of Indiangrass at all six locations were heavily dependent on seasonal precipitation 

patterns. Seed origin and soils differences also affected overall performance. Rumsey, originating from 

southern Illinois, suffered winter injury at all six locations. Tomahawk, the northernmost variety in the test 

(central North Dakota) performed best at Upham, the northernmost evaluation site. Previous studies at the 

Bismarck PMC have shown that generally warm-season 

grass species can be moved about 300 miles north or 

200 miles south of their original collection location 

without serious impact on performance. East and west 

movement is affected by moisture and elevation (USDA 

NRCS 2006). Varieties with the highest biomass yield 

varied across the plot locations, but generally the more 

southern origin seed sources produced the most biomass, 

if winter injury was not a problem. Additional winter 

injury is anticipated when the southern origin varieties 

are grazed or hayed. Indiangrass that is locally adapted 

should be used for native or natural area plantings. 

Production of viable offspring (seed) and winter survival 

are important components of local adaptation. Winter 

survival is associated with the plants ability to “harden 

off” and have enough regrowth to capture and store the 

necessary carbohydrates.

Stand index densities were rated at all six sites. 

Generally, the varieties with the highest biomass yields 

also had the highest stand index ratings. The exception 

was Rumsey. Following winter die-back, the remaining 

plants of Rumsey responded with higher biomass 

because of the decrease in plant competition. Winter 

injury was less noticeable the second year with older 

plants. Osage and Oto also received winter injury at the 

northernmost evaluation site at Upham.

Phenology was similar across sites even though annual rainfall varied greatly. Tomahawk had mature seed 

in early August at Upham, and in early September at the remaining five sites. Holt was the next variety to 

mature at all the sites and varied from first anthesis to first seed ripe when Tomahawk had mature seed. Oto, 

Osage, and Rumsey were similar at all the sites during the evaluation period and varied from the vegetative 

growth stage to the first emergence of inflorescence growth stage. None of these three varieties produced 

mature seed at any of the six test sites. 

12

Flowering dates varied depending 

on the origin of the variety
Variety Recommendations for North Dakota, South Dakota, and Minnesota

Variety Origin

Average Number of 

Days to Ripe Seed 

after July 15

Where Adapted

Tomahawk

south central North Dakota,

north central South Dakota 60 ND, SD, MN

Holt northeastern Nebraska 90

SD; south half of MN; 

southeast and south central ND

Oto Nebraska, Kansas 110

south half of SD; south quarter of MN;

not recommended in ND

Osage

eastern and central

Kansas and Oklahoma 120 not recommended in ND, SD, MN

Rumsey southern Illinois 120 not recommended in ND, SD, MN

13

Indiangrass seed 

with awns

Indiangrass seed 

with awns removed (debearded)

Key Establishment and Management Considerations

•	 Soils/Adaptation: Plant performance is best on moist, well drained, moderate to fine textured deep 

soils in areas of greater than 14 inches of average annual precipitation. Indiangrass will decline from 

stands during periods of drought on dry sites.

•	 Seeding: Indiangrass seed is similar to big bluestem seed in appearance and has approximately 

193,000 seeds per pound. The seed also has hairy appendages (awns). Using debearded seed (awns 

removed) greatly improves seed flow through a grass drill. The extent of debearding may vary 

among seed lots. If seed is not debearded it should be planted through the chaffy seed box found 

on most grass drills. The NRCS recommended drilled seeding rate for North Dakota is 7 lbs/ac 

(approximately 30 seeds/sq ft) in the east and 5.5 lbs/ac (approximately 25 seeds/sq ft) in the west 

(Sedivec et al 2001). Rates are calculated based on Pure Live Seed (PLS). Broadcast seeding rates 

are higher than the recommended drilled seeding rates, and are generally doubled. Seeding rates vary 

across the United States, generally increasing from west to east. Spring seeding is recommended. A 

firm seedbed is essential for a shallow seeding depth (1⁄2 – 3⁄4 inch). Germination is greatly reduced 

when seeds are planted deeper than one inch (USDA NRCS 2003). 
•	 Weed Control: Abundant broadleaf weeds and annual grasses need to be controlled by mowing 

and/or herbicide application. Dense stands of foxtail (Setaria species) can be very competitive and 

significantly reduce stand establishment. Herbicides generally are more effective than mowing in 

controlling annual grasses.

•	 Fertilization: Biomass yield, quality and seed production can be improved with fertilization if 

nitrogen or other nutrients are limiting. A soil test is recommended.

•	 Grazing/Haying/Mowing: Indiangrass is considered a high quality forage species for all classes 

of livestock. It will provide good grazing during the summer months. A stubble height of 6 inches 

is recommended to assure stand longevity. A rotational grazing system can extend immature plant 

growth through early fall, reduce trampling loss, enhance utilization, and increase nutritional quality 

and palatability. Indiangrass can make good hay; however, it typically is not recommended in pure 

stands for hayland in the Northern Plains. It may be mixed with big bluestem or other warm-season 

species (USDA NRCS 2008). 

•	 Burning: Indiangrass benefits from burning of plant residue prior to initiation of spring growth. 

Advantages to burning include low impact residue removal, weed control, more uniform growth 

initiation and seed ripening, improved nutrient cycling, and more vigorous growth. Burning annually 

at the Bismarck PMC has increased long-term seed yields.

•	 Seed Harvest: Seed shattering may occur shortly after the first seed is ripe. Conventional grain 

harvesting equipment can be used with proper setting adjustments, screen sizes, and reduced air flow. 

The awns on the seed may cause problems with seed flowing through the combine. Seed strippers 

work well for harvesting Indiangrass seed. Seed is subject to heating, and moisture levels may 

require drying. Air drying is recommended as heat may cause damage to the seed. Fields should be 

as weed free as possible prior to harvest to aid in the seed cleaning process.

A prescribed burn is an important management tool

14
References

Jacobson, E.T., D.A. Tober, R.J. Haas, and D.C. Darris. 1986. The performance of selected cultivars of 

warm-season grasses in the northern prairie and plains states. p. 215-221. In G.K. Clambey and R.H. 

Pemble (ed.) Proc. North Am. Prairie Conf., 9th, Moorhead, MN. 29 July-1 Aug. 1984 Tri-College Univ. 

Cent. for Environ. Studies, North Dakota State Univ., Fargo.

Sedivec, K., D. Tober, J. Berdahl. 2001. Grass varieties for North Dakota. NDSU Extension Service, 

Fargo, ND. 20p.

USDA NRCS Plant Materials Center. 1983, 1984, 1985, 1986/1987, 1988/1989, 1990/1991, 1992/1993. 

Technical report, part 1, grasses, forbs, and legumes, Bismarck, North Dakota

USDA NRCS. 2003. Five keys to successful grass seeding. Plant Materials Center, Bismarck, ND. 6p.

USDA NRCS. 2004. Plant fact sheet, Indiangrass. The PLANTS Database, National Plant Data Center, 

Baton Rouge, LA 70874-4490. Available at: http://plants.usda.gov. Accessed 5 March 2009.

USDA NRCS Plant Materials Center. 2006. Origins of native grass and forb releases. Bismarck, ND. 

brochure 12p.

USDA SCS. 1994. Grass varieties in the United States. Agric. Handbook No. 170. Washington, D.C. 

p. 194-199.

15

Indiangrass
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July 2009