SGINC1-07

June 2007

Composition of

Herbaceous Biomass Feedstocks

Composition of Herbaceous Biomass Feedstocks 

 DoKyoung Lee

 Vance N. Owens

 Arvid Boe

 Peter Jeranyama

 Plant Science Department

 South Dakota State University

	 	 This Report Sponsored by

 Sun Grant Initiative

 North Central Center

 South Dakota State University

	 	 Prepared by:

 North Central Sun Grant Center

 South Dakota State University

 Box 2140C

 Brookings, SD 57007
Contents

Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

1. Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

2. General Characteristics of Lignocellulosic Biomass. . . . . . . . . . . . . . . . . . . . . . . 6

3. Composition of Lignocellulosic Biomass Feedstock Resources. . . . . . . . . . . . . 7

	 3.1. Corn Stover, Wheat Straw, and Switchgrass. . . . . . . . . . . . . . . . . . . . . . . . . . . 7

	 3.2. Other Crops. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0

4. Harvest and Storage Issues. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 0

	 4.1 Harvest Timing. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 1

	 4.2. Storage. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 2

5. Summary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4

Glossary. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 4

References. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1 5

4
Summary

This report summarizes published information about the chemical composition of potential herbaceous biomass 

feedstocks for biorefineries in the north-central United States. The specific usefulness of this report varies 

according to conversion process; thus, values are intended only for exploratory calculations and preliminary 

estimates about the feasibility and economics of a particular feedstock. More detailed feedstock compositional 

information will become available as further research is completed at various locations throughout the country.

1. Introduction

National energy security and global climate change will require large-scale substitution of petroleum-based fuels 

by other sources of energy. One source of renewable energy will be biomass for use in transportation fuels. 

The U.S. Department of Energy (USDOE) and the U.S. Department of Agriculture (USDA) are strongly 

committed to expanding the role of lignocellulosic feedstocks as an energy source to reduce oil and gas imports. 

A goal set forth in “The United States Bioenergy Vision and Sustainable Feedstock Supply” by the Biomass R&D 

Technical Advisory Committee is that, by year 2030, 30% of current U.S. petroleum-based fuels will be replaced by 

biofuels. It has been estimated that an annual production of at least 1 billion dry tons of lignocellulosic feedstock 

will be required to meet this goal [1, 2]. 

The USDOE and USDA have estimated that more than 1.3 billion dry tons of biomass (368 million dry tons of 

biomass from forestlands and 998 million dry tons from agricultural lands) can be produced per year in the U.S. 

[2]. Biomass from agricultural lands would include 428 million dry tons of annual crop residues, 377 million 

dry tons of perennial crops, 87 million dry tons of grains, and 106 million dry tons of animal manure, process 

residues, and other miscellaneous sources.

Biomass is defined as consisting of all plant and plant-derived materials including livestock manures. 

Lignocellulosic biomass is the nonstarch, fibrous part of plant material and is an attractive resource because it is 

renewable and abundant [2]. 

Chemical composition 

of lignocellulosic 

feedstocks is a key factor 

affecting efficiency of 

biofuel production 

during conversion 

processes [3, 4]. The 

structural and chemical 

composition of 

lignocellulosic feedstocks 

is highly variable 

because of genetic 

and environmental 

influences and their 

interactions.

Switchgrass being harvested for biomass feedstock near Bristol, S.D. Photo by Jerry Roitsch. 

5
2. General Characteristics of Lignocellulosic Feedstocks

Lignocellulosic feedstocks are composed primarily of carbohydrate polymers (cellulose and hemicellulose) and 

phenolic polymers (lignin). Lower concentrations of various other compounds, such as proteins, acids, salts, and 

minerals, are also present.

Cellulose and hemicellulose, which typically make up two-thirds of cell wall dry matter (dry matter: the portion 

of biomass that is not water), are polysaccharides that can be hydrolyzed to sugars and then fermented to ethanol. 

Process performance, in this case ethanol yield from biomass, is directly related to cellulose, hemicellulose, and 

individual sugar concentration in the feedstock. Lignin cannot be used in fermentation processes; however, it may 

be useful for other purposes. 

Important Constituents of Lignocellulosic 

Feedstocks

Lignocellulose is the term used to describe the 

three-dimensional polymeric composites formed 

by plants as structural material. It consists of 

variable amounts of cellulose, hemicellulose, and 

lignin [5].

Cellulose (30–50% of total feedstock dry matter) is 

a glucose polymer linked by ß–1,4 glycosidic bonds. 

The basic building block of this linear polymer is 

cellubiose, a glucose-glucose dimer (dimer: two 

simpler molecules—monomers—combined to 

form a polymer). Hydrolysis of cellulose results in 

individual glucose monomers. This process is also 

known as saccharification.

Hemicellulose (20–40% of total feedstock 

dry matter) is a short, highly branched polymer of five-carbon (C5) and six-carbon (C6) sugars. Specifically, 

hemicellulose contains xylose and arabinose (C5 sugars) and galactose, glucose, and mannose (C6 sugars). 

Hemicellulose is more readily hydrolyzed compared to cellulose because of its branched, amorphous nature. A 

major product of hemicellulose hydrolysis is the C5 sugar xylose.

Lignin (15–25% of total feedstock dry matter), a polyphenolic structural constituent of plants, is the largest 

non-carbohydrate fraction of lignocellulose. Unlike cellulose and hemicellulose, lignin cannot be utilized in 

fermentation processes. 

Ash (3–10% of total feedstock dry matter) is the residue remaining after ignition (dry oxidation at 575 ± 25°C) of 

herbaceous biomass. It is composed of minerals such as silicon, aluminum, calcium, magnesium, potassium, and 

sodium.

Other compounds present in lignocellulosic feedstocks are known as extractives. These include resins, fats and 

fatty acids, phenolics, phytosterols, salts, minerals, and other compounds. 

6

Other

5-35%

Lignin

15-25%

Hemicellulose

20-40%

Cellulose

30-50%

Fig. 1. General composition of lignocellulosic 

biomass feedstocks
3. Composition of Lignocellulosic Biomass Feedstock Resources

An ideal biomass resource will be high yieding, have low production costs, be readily available, and have consistent 

desirable chemical concentrations. The feasibility of a new energy crop will depend largely on its production costs, 

cost of converting the biomass to usable energy, and cost of competing fuels. 

Agriculture-derived biomass, specifically crop residues from corn and small grains and dedicated perennial grasses 

such as switchgrass, are emphasized in this report. Table 1 lists general characteristics of these and other potential 

biomass resources.

3.1. Corn Stover, Wheat Straw, and Switchgrass

The most probable feedstocks for initial processing facilities would be low-cost agricultural residues because of 

their abundance and proximity to existing grain-to-ethanol conversion facilities. 

On the other hand, it is assumed that significant amounts of land could be shifted to production of perennial 

energy crops if a large market for bioenergy and biobased products emerges. Characteristics which make perennial 

grasses attractive for biomass production are yield potential, high concentration of lignocellulose, and generally 

positive environmental impact. 

The chemical composition of switchgrass, corn stover, and wheat straw is relatively similar when harvested to 

maximize the lignocellulosic component (Fig 2). However, when grown in different environments, considerable 

variation in feedstock composition may occur, as demonstrated by the range of data reported for these crops in 

the literature (Table 2). In addition to the range in genetics, environmental effects on feedstock composition also 

are significant.

Corn stover-to-grain ratios are about 1:1 on a dry matter basis, and corn stover is about 38% cellulose, 26% 

hemicellulose, and 19% lignin. 

Wheat straw yields, dry matter basis, are about 1.3–1.4 lb straw per 1 lb grain. Wheat straw is about 38% cellulose, 

29% hemicellulose, and 15% lignin. 

Similarly, switchgrass biomass on a dry matter basis is about 37% cellulose, 29% hemicellulose, and 19% lignin 

during late autumn.

7
8

Table 1. Composition of potential lignocellulosic biomass resources.a

Acid

Hemi- detergent Crude 

Cellulosec cellulosec Lignind lignine proteinf Ash References

% of dry matter 

Crop residues

Corn stover 38 26 19 4 5 6 6, 7-20

Soybean 33 14 - 14 5 6 48, 49

Wheat straw 38 29 15 9 4 6 7, 9, 11, 21-26

Rye straw 31 25 - 3 3 6 38, 39

Barley straw 42 28 - 7 7 11 11

Warm-season grasses

Switchgrass 37 29 19 6 3 6 6, 7, 11, 27-37

Big bluestem 37 28 18 6 6 6 32, 33, 37

Indiangrass 39 29 - 6 3 8 32, 37

Little bluestem 35 31 - - - 7 37

Prairie cordgrass 41 33 - 6 3 6 46

Miscanthus 43 24 19 - 3 2 42-45

Cool-season grasses

Intermediate wheatgrass 35 29 - 6 3 6 33

Reed canarygrassb 24 36 - 2 10 8 47, 48

Smooth bromegrassb 32 36 - 6 14 8 47, 48

Timothyb 28 30 - 5 7 6 40, 41

Tall fescue 25 25 14 - 13 11 7

Other crops

Alfalfab 27 12 - 8 17 9 40

Forage sorghum 34 17 16 - - 5 7

Sweet sorghum 23 14 11 - - 5 7

Pearl milletb 25 35 - 3 10 9 47, 48

Sudangrass 33 27 - 8 12 12 47, 48

a

Values in table are means or values obtained from cited references. 

b

Data for these species were available for hay only. All other species harvested for biomass. 

c

Reported directly from literature, calculated from individual sugars (Cellulose = Glucan; Hemicellulose = Xylan + Arabinan + Galactan 

+ Mannose), or based on fiber analysis (Cellulose = ADF- ADL; Hemicellulose = NDF – ADF). 

d

Lignin is total lignin (acid soluble lignin + acid insoluble lignin), which is measured using ASTM standard method. 

e

Acid detergent lignin (ADL) is commonly used for forage. In general, acid insoluble lignin is 30% higher than ADL for legumes and 

2 to 4 times greater than ADL for grasses [50]. 

f

Reported directly from literature or calculated from total nitrogen (crude protein = % total N * 6.25).
Table 2. Detailed compositional analysis of switchgrass, corn stover, and wheat straw.a

Minimum Maximum Mean SD

——————————% of dry matter ——————————

Corn Stover

Celluloseb 31.3 41 37.5 2.8

Structural glucan 33.8 41 37.5 2.2

Hemicellulose 20 34.4 26.1 4.8

Xylan 19.8 25.8 21.7 2.1

Arabinan 1.7 6.1 2.7 1.6

Galactan 0.7 3 1.6 1

Mannan 0.3 1.8 0.6 1.1

Total lignin 15.8 23.1 18.9 2.6

Acid soluble lignin 1.9 3.6 2.9 0.9

Acid insoluble lignin 13.6 19.8 16.4 3.1

Acid detergent lignin 3.1 5 4.1 1.3

Crude protein 3.5 8.7 4.7 2.2

Ash 4.2 7.5 6.3 1.2

Soil - - 1.3 -

Wheat Straw

Cellulose 31.5 48.6 37.6 5.7

Structural glucan 31.5 32.6 32.1 4.5

Hemicellulose 22.6 38.8 28.8 5.7

Xylan 19.2 19.7 19.5 0.3

Arabinan 2.4 3.2 2.8 0.6

Galactan 0.8 1.5 1.1 0.5

Mannan 0.3 0.9 0.6 0.4

Total lignin 5.3 19 14.5 6.2

Acid soluble lignin - - 2.5 -

Acid insoluble lignin 5.3 16.5 10.9 7.9

Acid detergent lignin 7.6 11.2 9.2 1.6

Crude protein 1.9 5.7 3.8 1.9

Ash 1.4 10.2 6.4 3.4

Soil - - - -

Switchgrass

Cellulose 31.4 45 37.3 4.4

Structural glucan 31.4 38 34.2 2.1

Hemicellulose 22 35.1 28.5 3.5

Xylan 20.2 24 22.8 1

Arabinan 2.7 3.8 3.1 0.5

Galactan 0.7 1.9 1.4 0.5

Mannan 0.3 0.4 0.3 0

Total lignin 17.7 22 19.1 1.7

Acid soluble lignin 3.3 3.7 3.5 0.3

Acid insoluble lignin 15.8 16.5 16.2 0.5

Acid detergent lignin 4 12 6.4 2.7

Crude protein 1.6 3.8 3.1 0.7

Ash 4.4 8.5 5.9 1

Soil - - - -

a

Values in table are compiled from references listed in Table 1. b

Cellulose and hemicellulose values may not equal the sum of individual sugars because of limited data for individual sugars.

9
3.2 Other Crops

Other potential biomass crops may have levels of lignocellulose comparable to switchgrass, corn stover, and 

wheat straw at similar stages of maturity (Tables 1 and 2). However, warm-season grasses generally contain higher 

concentrations of lignocellulose than crop residues and cool-season grasses (Table 1).

4. Harvest and Storage Issues

Biomass feedstock composition is affected by time and method of harvest and storage. 

Several studies have been published regarding the effect of harvest timing on feedstock composition [50, 34, 

20] particularly as harvest timing relates to optimizing lignocellulosic concentrations. There is less published 

information about storage of biomass resources for biorefineries. 

However, since biorefineries will require a consistent supply of product, feedstock storage either at the farm or at 

the biorefinery will be necessary. Storage examples for round bales of switchgrass and corn stover are discussed in 

section 4.2.

0 20 40 60 80 100

37.3

37.5

37.6

28.5

26.1

28.8

19.1

18.9

14.5

3

5

4

6

6

6

Switchgrass

Corn stover

Wheat straw

Cellulose

Hemicellulose

Lingnin Protein

Ash

Percent (%)

Fig 2. Comparison of feedstock composition of switchgrass, corn stover, and wheat straw 

harvested for maximum lignocellulose. Data were summarized from Table 3. 

10
4.1 Harvest Timing

Feedstock composition varies with crop maturity. Maximum lignocellulosic yield for corn is obtained when 

corn stover fractions are harvested at physiological maturity. For switchgrass, maximum yield is obtained when 

harvested around anthesis; however, stand health and longevity will decrease as a result of harvesting annually 

at anthesis. Therefore, harvesting around a killing frost in the fall is recommended for switchgrass grown for 

biomass. A reduction in certain chemical elements that reduce process performance is an added benefit of 

harvesting later in the season. 

In corn, soluble solids rapidly decrease and lignin and xylan increase shortly after grain physiological maturity

(Table 3) [12]. In switchgrass, cellulose, hemicellulose, and lignin concentrations increase while total nitrogen 

and ash content decreases when harvest is delayed from anthesis to a killing frost (Table 4) [33]. In switchgrass 

biomass, total potassium (K) and water extractable chlorine (Cl) decrease 60% and 70%, respectively, when 

harvest is delayed from green stem to late winter (Table 5) [27]. Other warm-season perennial grasses would likely 

behave similarly; however, research with individual species is required to verify this assertion.

Table 3. Changes in composition of corn stalk and leaf with crop maturity.

Late dent Physiological Post physiological 

(110da) maturity (153d) maturity (220d)

————————————% of dry matter ———————————

Corn stalk

Structural glucan 35 35 35

Xylan 16 22 23

Lignin 15 20 19

Protein 3 4 4

Soluble solids 15 4 4

Corn Leaf

Structural glucan 18 23 32

Xylan 2 17 22

Lignin 4 13 16

Protein 8 8 4

Soluble solids 35 8 6

Source: [12]\

a

Days after planting

Table 4. Changes in composition of ‘Nebraska 28’ switchgrass with crop maturity.

Harvest Timea

Anthesisa Post physiological maturity Overwintered 

———————————— % of dry matter ———————————

11
4.2. Storage

Any large-scale biofuel production facility needs the capacity to store biomass feedstocks for 6–12 months to 

ensure continuous availability during the year. Quantity and time of feedstock in storage will depend on size and 

requirements of the biorefinery, available storage capacity, distance from producer fields to the biorefinery, and 

other issues. 

Covered storage for bales of lignocellulosic feedstocks is unlikely to be economical or practical considering the 

quantities involved. However, unprotected outside storage results in feedstock losses that can cause potential 

economic and efficiency losses in any energy conversion process. 

Feedstock losses can be categorized in terms of loss of dry matter and in compositional changes. In a 2-year trial, 

loss of extractives was greater for switchgrass stored outside than inside, particularly during the first year when 

total precipitation was 69% higher than in the second year (Table 6) [6, 20]. However, in the same study, little or 

no change was observed for cellulose, hemicellulose, and lignin in either switchgrass or corn stover bales 

(Tables 6 and 7) [6, 20]. 

Protein 8 8 4

Soluble solids 35 8 6

Source: [12]\

a

Days after planting

Table 4. Changes in composition of ‘Nebraska 28’ switchgrass with crop maturity.

Harvest Timea

Anthesisa Post physiological maturity Overwintered 

———————————— % of dry matter ———————————

Cellulose 33.0 35.2 41.8

Hemicellulose 31.0 31.1 33.7

Acid detergent lignin 3.8 4.6 6.2

Protein 5.3 2.3 1.8

Ash 6.5 5.8 5.2

Source: [33] 

a

Harvest time: Anthesis, early August; post physiological maturity, November; and overwintered,spring of following year near 

Brookings, S.D.

Table 6. Changes in composition of switchgrass round bales during storage.

Harvest 1 (Oct. 1991) Harvest 2 (Aug. 1992)

Time zero 26 weeks storage Time Zero 26 weeks storage

Inside Outside Inside Outside

% of dry matter % change % of dry matter % change

Composition on whole biomass basis

Extractives 17.0 -7.7 -10.5 14.2 <0.6 -1.8

Ash 5.8 +0.3 +0.2 4.8 <1.0 <1.0

Protein 3.2 +0.6 +0.6 2.8 -0.8 -0.9

Composition on extractive-free basis

Lignin 21.4 +0.8 +1.5 20.6 -0.5 -0.4

Arabinan 3.4 -0.4 -0.4 3.2 <0.2 <0.2

Xylan 24.9 -1.5 -1.6 25.5 <1.3 <1.3

Table 5. Changes in potassium and chloride in switchgrass biomass with crop maturity.

Harvest Timea

Green stem Dead stem Late winter

————————————ppm of dry matter —————————

Total potassium 5580 2555 1961

Water extractable chloride 3283 1412 972

Source: [27] 

a

Harvest time: Green stem, after anthesis; Dead stem, post physiological maturity.

12
Table 7. Changes in composition of corn stover square bales during storage.

Time zero 26 weeks storage 52 weeks storage

Inside Outside Inside Outside

% of dry weight % change % change

Composition on whole biomass basis

Extractives 7.6 <1.4 -2.5 -2.9 -2.3

Ash 6.8 -1.3 -1.3 <1.1 <1.1

Composition on extractive-free basis

Lignin 18.5 +2.7 +0.9 +3.7 +3.0

Arbinan 3.4 -0.7 -0.5 -1.0 -0.8

Xylan 20.1 <0.8 +0.9 +2.0 +2.8

Mannan 0.7 -0.1 -0.1 -0.2 -0.2

Galactan 1.1 -0.1 <0.1 -0.3 +0.1

Glucan 40.7 -1.5 <1.6 -1.6 <0.6

Source: [6 and 20]

Table 6. Changes in composition of switchgrass round bales during storage.

Harvest 1 (Oct. 1991) Harvest 2 (Aug. 1992)

Time zero 26 weeks storage Time Zero 26 weeks storage

Inside Outside Inside Outside

% of dry matter % change % of dry matter % change

Composition on whole biomass basis

Extractives 17.0 -7.7 -10.5 14.2 <0.6 -1.8

Ash 5.8 +0.3 +0.2 4.8 <1.0 <1.0

Protein 3.2 +0.6 +0.6 2.8 -0.8 -0.9

Composition on extractive-free basis

Lignin 21.4 +0.8 +1.5 20.6 -0.5 -0.4

Arabinan 3.4 -0.4 -0.4 3.2 <0.2 <0.2

Xylan 24.9 -1.5 -1.6 25.5 <1.3 <1.3

Mannan 0.4 <0.1 +1.4 0.3 <0.2 <0.2

Galactan 1.1 <0.1 <0.1 1.0 +0.1 <0.1

Glucan 37.8 -2.1 -2.2 40.8 <2.5 <2.5

Source: [6 and 20]

Harvest Timea

Green stem Dead stem Late winter

————————————ppm of dry matter —————————

Total potassium 5580 2555 1961

Water extractable chloride 3283 1412 972

Source: [27] 

a

Harvest time: Green stem, after anthesis; Dead stem, post physiological maturity.

13
5. Summary

This review of data from published and electronic sources indicated:

1. When switchgrass was harvested at physiological maturity and corn stover and wheat straw were harvested 

after grain removal, their chemical compositions were found to be similar.

2. Other potential biomass feedstocks, including other cereal crop residues and annual and perennial warmand cool-season grasses, may be expected to have comparable levels of lignocellulose as switchgrass, corn 

stover, and wheat straw when harvested after physiological maturity.

Glossary

Acid detergent fiber (ADF): Organic matter that is not solubilized after 1 hour of refluxing in an acid detergent 

solution consisting of acetyltrimethylammonium bromide in 1N sulfuric acid. ADF includes cellulose, lignin, and 

ash. This analytical method is commonly used in the feed and fiber industries. 

Acid detergent lignin (ADL): Organic matter that is not solubilized after 3 hours of extraction in 72% sulfuric 

acid.

Dimer: Molecules composed of two similar subunits or monomers linked together. Sucrose is a dimer, composed 

of a glucose molecule and a fructose molecule.

Dry matter: Moisture-free biomass, obtained by drying a sample or specimen at high temperature (105o C).

Extractives: Any number of different compounds in biomass that are not an integral part of the cellular structure. 

The compounds can be extracted from biomass by means of polar and non-polar solvents including hot or 

cold water, ether, benzene, methanol, or other solvents that do not degrade the biomass structure. The types of 

extractives found in biomass samples are entirely dependent upon the sample itself.

Genetic: Pertaining to or concerned with inheritance.

Glucan: A glucose polymer, which can be hydrolyzed (split into two parts by adding water) to glucose. Cellulose is 

a form of glucan.

Neutral detergent fiber (NDF): Organic matter that is not solubilized after one hour of refluxing in a neutral

detergent solution consisting of sodium laruryl sulfate and EDTA at pH 7. NDF includes hemicellulose, cellulose, 

lignin, and ash.

Phenology: Periodicity in organisms as related to climate events; in plants, the various biological processes that 

are correlated with the seasons, e.g. flowering, fruiting, dormancy, root or stem elongation, etc.

Physiological maturity: The plant maturity stage at which no new dry matter is added to the plant.

Polymer: Very large molecules formed by linking together a large number of repeating structural units, or 

monomers.

Senescence: The growth phase in a plant or plant part (as a leaf) from full maturity to death during which time 

significant drying occurs.

Xylan: A xylose polymer and a major portion of hemicellulose. It can be hydrolyzed to xylose. 

14
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South Dakota State University, South Dakota counties, and U.S. Department of Agriculture cooperating. South Dakota State University is an Affirmative Action/Equal Opportunity Employer 

and offers all benefits, services, education, and employment opportunities without regard for race, color, creed, religion, national origin, ancestry, citizenship, age, gender, sexual orientation, 

disability, or Vietnam Era veteran status. SGINC1-07 June 2007 http://agbiopubs.sdstate.edu/articles/SGINC1-07.pdf

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