biomass and energy yields of bioenergy...

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BIOMASS AND ENERGY YIELDS OF BIOENERGY GERMPLASM GROWN ON SANDY

SOILS IN FLORIDA

By

PEDRO HENRIQUE KORNDÖRFER

A THESIS PRESENTED TO THE GRADUATE SCHOOL

OF THE UNIVERSITY OF FLORIDA IN PARTIAL FULFILLMENT

OF THE REQUIREMENTS FOR THE DEGREE OF

MASTER OF SCIENCE

UNIVERSITY OF FLORIDA

2011

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© 2011 Pedro Henrique Korndörfer

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To my beloved family

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ACKNOWLEDGMENTS

I wish to extend my deep thanks and gratitude to Dr. Robert A. Gilbert, Chairman of the

Supervisory Committee, for his guidance, assistance, and useful criticism throughout the

duration of my graduate program. I feel indebted for his help, support, and understanding.

I also would like to thank Dr. Zane R. Helsel, for his guidance, assistance and advice

throughout my work. I would like to express my appreciation to Drs. John E. Erickson and Lynn

E. Sollenberger, who where always there to answer my questions, contribute with their expertise

to this research and for serving as members of the Supervisory Committee.

I am thankful for the endless love, encouragement and support of my family. To my

parents, Gaspar and Clotilde, to my sisters, Letícia, Ana Paula, and Andréa Luisa, and to my

fiancé, Camilla, who pushed me forward throughout my academic progress, my thanks cannot be

adequately acknowledged with words. The encouragement, help, and friendship of Miguel

Castillo, Daniel Pereira, and Barbara Martin, is also sincerely acknowledged.

Thanks also are due to the staff of the Everglades Research and Education Center at Belle

Glade, Florida. I wish to thank Jairo Sanchez and Miguel Baltazar for their assistance in planting,

sampling, and harvesting of the experiments, and laboratory analysis.

Finally, I would like to acknowledge the support from Florida Crystals/Okeelanta

Corporation and U.S. Sugar Corporation for providing the experimental areas and the mechanical

equipment for field preparation, crop management and harvests.

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TABLE OF CONTENTS

page

ACKNOWLEDGMENTS ...............................................................................................................4

LIST OF TABLES ...........................................................................................................................7

LIST OF FIGURES .........................................................................................................................9

ABSTRACT ...................................................................................................................................10

CHAPTER

1 INTRODUCTION ..................................................................................................................12

2 LITERATURE REVIEW .......................................................................................................15

2.1 Background ...................................................................................................................15

2.1.1 Use of Perennial Grasses as Energy Crops .......................................................15

2.1.2 Cellulosic Ethanol .............................................................................................15

2.1.3 State of Florida: Potential for Biomass Energy Crop Production .....................16

2.2 Grasses as Lignocellulosic Feedstock ...........................................................................16

2.2.1 Energycane (Saccharum spontaneum hybrids) .................................................18

2.2.2 Elephantgrass (Pennisetum purpureum Schum.) ..............................................19

2.2.3 Giant reed (Arundo donax L.) ...........................................................................21

3 CROP GROWTH AND BIOMASS YIELDS FROM BIOENERGY GRASS SPECIES

GROWN ON SANDY SOILS OF FLORIDA .......................................................................23

3.1 Materials and Methods ..................................................................................................25

3.1.1 Soil and Climatic Conditions ............................................................................25

3.1.2 Field Experiment Design and Management ......................................................26

3.1.3 Genotype Selection ...........................................................................................27

3.1.4 Measurements and Analysis ..............................................................................28

3.1.5 Statistical Analysis ............................................................................................30

3.2 Results ...........................................................................................................................31

3.2.1 Tecan Analysis ..................................................................................................31

3.2.2 Townsite Analysis .............................................................................................32

3.2.3 Combined Analysis ...........................................................................................33

3.3 Discussion .....................................................................................................................34

4 FIBER CONCENTRATION, CALORIFIC VALUE, AND ASH CONCENTRATION

OF BIOENERGY GRASS SPECIES GROWN ON SANDY SOILS OF FLORIDA ..........49

4.1 Materials and Methods ..................................................................................................50

4.1.1 Measurements and Analysis ..............................................................................51

4.1.2 Statistical Analysis ............................................................................................53

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4.2 Results ...........................................................................................................................54

4.2.1 Tecan Analysis ..................................................................................................54

4.2.2 Townsite Analysis .............................................................................................55

4.2.3 Combined Analysis ...........................................................................................56

4.3 Discussion .....................................................................................................................57

5 SUMMARY AND CONCLUSIONS .....................................................................................72

LIST OF REFERENCES ...............................................................................................................73

BIOGRAPHICAL SKETCH .........................................................................................................80

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LIST OF TABLES

Table page

3-1 Analysis of variance F ratios and level of significance for juice concentration, Brix,

and moisture concentration for crop and genotype effects and their interaction at the

Tecan location. ...................................................................................................................38

3-2 Juice concentration, Brix, and moisture concentration for giant reed, energycane, and

elephantgrass genotypes at Tecan. .....................................................................................38

3-3 Crop x genotype interaction means for Brix of giant reed, energycane, and

elephantgrass genotypes at the Tecan location. .................................................................39

3-4 Analysis of variance F ratios and level of significance for fresh and dry yields for

crop and genotype effects and their interaction at the Tecan location. ..............................39

3-5 Fresh and dry yields for giant reed, energycane, and elephantgrass genotypes at

Tecan. .................................................................................................................................40


and moisture concentration for crop and genotype effects and their interaction at the

Townsite location. ..............................................................................................................40

3-7 Juice concentration, Brix, and moisture concentration for giant reed and energycane

genotypes at Townsite. .......................................................................................................41

3-8 Analysis of variance F ratios and level of significance for fresh and dry yields for

crop and genotype effects and their interaction at Townsite. ............................................41

3-9 Fresh and dry yields for giant reed and energycane genotypes at Townsite. ....................42


and moisture concentration for crop, genotype, and site effects and their interactions. ....42

3-11 Crop x genotype interaction means for Brix yield. ............................................................43

4-1 Analysis of variance F ratios and level of significance for cellulose, hemicellulose,

and lignin concentration (conc.) and yield for crop and genotype effects and their

interaction at Tecan. ...........................................................................................................61

4-2 Cellulose, hemicellulose, and lignin concentrations and yield for giant reed,

energycane, and elephantgrass genotypes at Tecan. ..........................................................61

4-3 Analysis of variance F ratios and level of significance for ash concentration and

HHV value for crop and genotype effects and their interaction at the Tecan location. .....62

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4-4 Crop x genotype interaction means for hemicellulose and HHV of giant reed,

energycane, and elephantgrass genotypes at the Tecan location. ......................................62


and lignin concentration and yield for crop and genotype effects and their interaction

at Townsite. ........................................................................................................................63

4-6 Genotype effect for cellulose, hemicellulose, and lignin concentrations and yield for

giant reed and energycane genotypes at Townsite. ............................................................63

4-7 Analysis of variance F ratios and level of significance for ash concentration and

HHV for crop and genotype effects and their interaction at the Townsite location. .........63


and lignin concentration and total yield for crop, site, and genotype effects and their

interaction. .........................................................................................................................64

4-9 Crop x genotype interaction means for hemicellulose yield. .............................................64

4-10 Genotype x site interaction means for hemicellulose yields of giant reed and

energycane genotypes. .......................................................................................................65

4-11 Genotype x site x crop interaction means for cellulose concentration of giant reed

and energycane genotypes .................................................................................................66

4-12 F ratios and level of significance for ash concentration and HHV for crop, site, and

genotype effects and their interaction. ...............................................................................67

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LIST OF FIGURES

Figure page

3-1 Monthly rainfall, maximum and minimum temperatures at Tecan and Townsite

locations. ............................................................................................................................44

3-2 Genotype leaf area index (LAI) in first ratoon crop at Tecan (A) and Townsite (B). .......45

3-3 Crop treatment effect means for juice concentration (A), Brix (B), and moisture

concentration (C) in the plant cane and first ratoon crops at Tecan. .................................45

3-4 Crop means for fresh yield (A) and dry yield (B) in the plant cane and first ratoon

crops at Tecan. ...................................................................................................................46

3-5 Crop means for juice concentration (A), Brix (B), and moisture concentration (C) in

the plant cane and first ratoon crop at Townsite ................................................................46

3-6 Crop by genotype interaction means for Brix in plant cane and first ratoon crops at

Townsite. ............................................................................................................................47

3-7 Crop effect means for fresh yield (A) and dry yield (B) in the plant cane and first

ratoon crops at Townsite. ...................................................................................................47

3-8 Crop by site interaction means for juice concentration (A), Brix (B), and moisture

concentration (C) in the plant cane and first ratoon crops at Tecan and Townsite. ...........48

3-9 Crop x site interaction means for fresh yield (A) and dry yield (B) in the plant cane

and first ratoon crops at Tecan and Townsite. ...................................................................48

4-1 Crop means for cellulose, hemicellulose, and lignin concentration (A) and dry yield

(B) at Tecan ........................................................................................................................67

4-2 Crop treatment means for ash concentration and higher heating value at Tecan. .............68

4-3 Crop effect means for cellulose, hemicellulose, and lignin concentration (A) and dry

yield (B) at Tecan. ..............................................................................................................68

4-4 Crop x genotype interaction means for cellulose concentration in the plant cane and

first ratoon crops at Townsite. ...........................................................................................69

4-5 Crop treatment effect means for ash concentration (A) and HHV (B) in plant cane

and first ratoon crop at the Townsite location. ..................................................................70

4-6 Crop x site interaction effect means for cellulose, hemicellulose, and lignin

concentration (A) and total yield (B) in the plant cane and first ratoon crops at Tecan

(TC) and Townsite (TS). ....................................................................................................70

4-7 Crop x site interaction effect means for ash concentration (A) and HHV (B). .................71

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Abstract of Thesis Presented to the Graduate School

of the University of Florida in Partial Fulfillment of the

Requirements for the Degree of Master of Science

BIOMASS AND ENERGY YIELDS OF BIOENERGY GERMPLASM GROWN ON SANDY

SOILS IN FLORIDA

By

Pedro Henrique Korndörfer

May 2011

Chair: Robert A. Gilbert

Cochair: Lynn E. Sollenberger

Major: Agronomy

The development of carbon-neutral energy sources has become one of the primary

challenges of the twenty-first century. Perennial grasses such as energycane [crosses of

commercial sugarcane hybrids (Saccharum spp.) with S. spontaneum], giant reed (Arundo donax

L.), and elephantgrass (Pennisetum purpureum Schum.), have been proposed as promising

feedstocks for lignocellulosic ethanol or direct combustion, and are expected to be grown on

marginal lands. The objectives of this study were to evaluate biomass yields and estimate fiber

concentration (cellulose, hemicellulose, and lignin), calorific value and ash concentration of

energycane and elephantgrass genotypes and giant reed in low-input rainfed sandy soil farming

systems of south Florida. Eight energycane genotypes (875-3, US 74-1010, US 78-1011, US 78-

1013, US 78-1014, US 82-1655, US 84-1047, and US 84-1066), ‘Merkeron’ and ‘Chinese Cross’

elehphantgrass, giant reed and a check cultivar of energycane (L 79-1002) were compared in a

randomized complete block design at two different mineral soil sites with differing organic

matter concentration, Tecan and Townsite, with 50 and 15 g kg-1

organic matter, respectively.

The experiment was evaluated during a two crop cycle (2008 to 2010). At Tecan, fresh yields

ranged from 53.9 to 69.3 Mg ha-1

in plant cane and 44.1 to 56.7 Mg ha-1

in first ratoon. Fresh and

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dry yields for giant reed at Tecan were extremely low, 10.1 and 5.3 Mg kg-1

, respectively.

Overall plant cane yields were lower and first ratoon yields were higher at Townsite than Tecan,

but the same yield and fiber concentration differences between energycane and giant reed were

observed. Our results showed that mean cellulose, hemicellulose, and lignin (mean of plant cane

and first ratoon crops) were 400, 273, and 81 g kg-1

, respectively across species. The overall

higher heating value (calorific value) of plant cane and first ratoon crops for the species in the

present study were 19.2 and 19.9 MJ kg-1

. Ash concentration ranged from 24.6 to 31.6 g kg-1

and

was positively correlated to the Si concentration. Our results indicate that energycanes and

elephantgrasses are more appropriate bioenergy feedstocks than giant reed for marginal sandy

soils of south Florida.

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CHAPTER 1

INTRODUCTION

The growing reliance on energy, the exhaustion of fossil fuel energy sources, and

significant changes in climate are combined factors that drive the increasing demand for

alternative energy sources. The carbon dioxide concentration of the atmosphere is projected to

increase by approximately 50% over the first 50 years of this century (IPCC, 2001). The major

cause of this increase is continued combustion of fossil fuels. As a result, significant changes in

climate will be accelerated, in particular global temperature increases. Therefore, the

development of carbon-neutral energy sources has become one of the primary challenges of the

twenty-first century.

There has been increasing concern in the U.S. regarding both sustainability and national

security issues surrounding imported fuels. Biomass has always been a major source of energy

for mankind and is presently estimated to contribute approximately 10 to 14% of the world’s

energy supply (Kaygusuz and Türker, 2002; Gross et al., 2003; Parikka, 2004). In 2008,

bioenergy provided 53% of all renewable energy, and 5% of the total energy produced in the

U.S. (EIA, 2009).

Renewable energy sources can improve energy security, decrease urban air pollution, and

reduce accumulation of carbon dioxide in the atmosphere (Lynd et al., 1991). Many energy

production and utilization cycles based on cellulosic biomass have near-zero greenhouse gas

emissions on a life-cycle basis (Lynd et al., 1991), meaning that all the carbon dioxide released

from plant energy will be sequestered in the subsequent crop, becoming a carbon neutral cycle.

Biomass energy sources are attractive due to their carbon-neutral balance and as renewable

alternatives to existing transport fuels (Schell et al., 2004). The technology of ethanol production

from non-food plant sources is being developed rapidly for large-scale production in the near

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future (Lin and Tanaka, 2006). However, production costs and species selection have been major

concerns (Cardinale et al., 2007).

Cellulosic ethanol is defined as the production of ethanol from feedstock containing

cellulose, such as agricultural wastes (sugarcane bagasse and corn stover), forestry wastes

(woodchips), grasses (Panicum virgatum and Miscanthus x giganteus), and others. Studies on

cellulosic ethanol production (Sticklen, 2008; Rubin, 2008; Lynd et al., 2008) have found that

the three main pillars are viable biomass production, cell wall degradation, and optimization of

fermentation of formed sugars (USDOE, 2006).

Species and genotype selection for biomass production is a fundamental step in the

production of cellulosic ethanol (McKendry, 2002). Total biomass yield, as well as fiber

concentration, cellulose, hemicellulose, and lignin, must be taken into account.

Identifying plants with high biomass production for marginal lands is critical for the

successful implementation of cellulosic biofuels. Perennial grasses are commonly considered as

potential lignocellulosic feedstocks for both energy and fiber production. These grasses possess

higher cellulose and lignin concentration than annual species (Dien et al., 2006), and are

characterized by having relatively low moisture concentration at the end of their growing cycle,

high water and nutrient-use efficiencies and low susceptibility to pest and diseases. Perennial

plant species may have high adaptation ability to produce in marginal lands. In addition, C4

perennial grasses are more efficient converters of light, water, and nutrients into biomass than are

C3 temperate species.

In summary, giant reed, energycanes, and elephantgrasses are perennial grasses species

that have many of the desired traits for addressing bioenergy crops, and they represent important

species for cellulosic ethanol production and industrial biomass combustion in the southeastern

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USA. However, little research has been performed on biomass and energy yields of these species

when grown on marginal lands in Florida. The objective of this thesis research was to document

realistic biomass yields, fiber characteristics, and energy content of these species for emerging

bioenergy industries in Florida.

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CHAPTER 2

LITERATURE REVIEW

Background

Use of Perennial Grasses as Energy Crops

Since the mid-1980s there has been significant interest in the use of perennial grasses as a

renewable source of energy in the U.S. and Europe (Lewandowski et al., 2003). The production

of transportation fuels, such as ethanol, as well as cogeneration for electricity and steam heat

production, are the two primary markets for bioenergy (McLaughlin and Kszos, 2005). Perennial

grasses have high biomass production and lignocellulose concentration (McKendry, 2002), as

well as high nutrient and water use efficiency (Lewandowski et al., 2003), attributes which have

contributed to interests in perennial grasses for biofuels. The literature review that follows

discusses the potential of grasses as lignocellulosic feedstocks, explores the potential of selected

perennial grass genotypes as bioenergy crops, and evaluates their biomass production and

composition when grown in marginal lands.

Cellulosic Ethanol

Lignocellulosic biomass from grasses provides an abundant and renewable source of

sugars for the fermentation of cellulosic ethanol. Lignocellulose represents the majority of plant

dry biomass. Lignocellulose is composed primarily of organic carbohydrates (cellulose,

hemicellulose, and pectin), aromatic polymers (lignin) (Fengel and Weneger, 1984; Ingram et al.,

1999), and inorganic components which remain as ash following combustion (Wiselogel et al.,

1996). The plant cell wall is composed of fibrils of cellulose (polysaccharide with glucose as its

monomer) embedded in a polymeric matrix of hemicellulose (xylan, glucuronoxylan,

arabinoxylan, or glucomannan) and lignin (guaiacyl) (Aspinall, 1980). Lignocellulosic

composition may vary among grass species, however it is generally composed of 200 to 500 g

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kg-1

cellulose, 200 to 400 g kg-1

hemicellulose, 20 to 200 g kg-1

pectin, and 100 to 200 g kg-1

lignin (Ingram et al., 1999).

Each of these components contributes to fiber properties, which ultimately impact the

lignocellulosic feedstock properties. In the cellulosic ethanol conversion process, cellulose and

hemicellulose components are broken down into simple sugars and fermented. Another fraction

of the biomass consists of lignin and insoluble extractives which are not fermented to ethanol

(Chang and Holtzapple, 2000; Laureano-Perez et al., 2005). Lignin suppresses the rate of

enzymatic hydrolysis in lignocellulosic ethanol processing, by preventing the digestible parts of

the substrate from hydrolyzing (Chang and Holtzapple, 2000). Lignin and other extractives

become a byproduct and may be used in combustion systems to generate heat energy or

electricity.

State of Florida: Potential for Biomass Energy Crop Production

The southeastern regions of the U.S., where sunlight and rainfall are abundant and growing

seasons are longer, is the optimum zone of the country for biomass production (USDA, 2010).

The state of Florida has favorable climatic conditions and low opportunity-cost land for

production of biomass crops, and can be considered as one of the leading areas in the United

States to produce biomass as a source of renewable energy. Florida is a subtropical region, with

one of the wettest climates in the U.S., receiving 1150 to 2050 mm of rain (Stricker et al., 1993).

The average number of frost-free days per year ranges from 240 in the Panhandle to 365 in the

Keys (Sanford, 2003). The precipitation and solar radiation throughout the year create favorable

climatic conditions for biomass accumulation in Florida.

Grasses as Lignocellulosic Feedstock

Since the mid-1980s, various perennial grasses have been proposed for bioenergy in

temperate and sub-tropical regions of the world. Giant reed (Arundo donax L.) (Angelini et al.,

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2009), miscanthus (Miscanthus x giganteus) (Lewandowski et al., 2003; Atkinson, 2009; and

Burner et al., 2009), energycane (Saccharum spontaneum hybrids) (Wang et al., 2008), and

elephantgrass (Pennisetum purpureum Schum.) (Woodard and Prine, 1993; Overman and

Woodard, 2006; and Morais et al., 2009) have been evaluated for bioenergy potential in both

Europe and the U.S.

Perennial grasses are ideal energy crops for cellulosic ethanol production, because they

contain high amounts of renewable lignocellulosic biomass, may have low input production

requirements, and are relatively inexpensive to produce (Kim and Dale, 2004; Bransby, 2008).

According to Long (2008), an ideal energy crop would be a photosynthetically-efficient C4

plant, recycle nutrients through its root system, require low inputs (nutrients, water and

pesticides), not have invasive characteristics, be resistant to pests and outcompete weeds, and

would not be difficult to harvest.

In cellulosic ethanol production, plant biomass is converted to fermentable sugars for the

production of biofuels using pretreatment processes that break down the lignocellulose and

remove the lignin, thus allowing microbial enzyme access for cellulosic fermentation to ethanol

(Sticklen, 2006). Cultivars containing high levels of cellulose would be preferred over those with

high levels of lignin. Lignin plays an important role in structurally supporting the plant to

prevent lodging. Thus, the benefits of lignin will need to be balanced against its negative effect

on the efficiency of cellulosic ethanol production in an energy crop breeding and selection

program (Tew and Cobill, 2008).

Successful production of cellulosic biofuel feedstocks will depend on improvement of

plant characteristics through traditional and molecular breeding methods. When breeding for

cellulosic ethanol production, selection criteria should include high fiber/sugar ratio, tolerance to

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biotic and abiotic stresses, high biomass yields, limited or late flowering, and no seed (Jakob et

al., 2009).

Energycane (Saccharum spontaneum hybrids)

Saccharum spontaneum is one of the six species of the genus Saccharum (Daniels and

Roach, 1987). Soltwedel in Java and Harrison and Bovell in Barbados, (later reviewed by

Mangelsdorf, 1946, and Stevenson, 1965), performed the first hybridization efforts involving S.

officinarum (sugarcane) and S. spontaneum (wild sugarcane) species. This cross resulted in a

hybrid (F1) which was more robust than the parental material. Clones of S. spontaneum have

long been used as sources of disease and pest resistance, ratooning performance, cold tolerance

and vigor in sugarcane breeding programs for commercial sucrose production. However it was

not until 2007 that L 79-1002, a high-fiber S. spontaneum hybrid, was released for energy

proposes in the U.S. (Bischoff et al., 2008). Energycane and sugarcane are from the same genus,

Saccharum, however energycanes have higher fiber/sugar ratios, thinner stalks and higher plant

populations then sugarcane.

L 79-1002 was evaluated from 2002 through 2005 by Legendre and Gravois (2007) at the

USDA-ARS Sugarcane Research Unit, in Houma, LA. They recorded average fresh weight cane

yields of 70.7 Mg ha-1

(Bischoff et al., 2008). Giamalva et al. (1984) reported average dry weight

cane yields of L 79-1002 over a five harvest period of 21 Mg ha-1

in Louisiana. Brix and fiber

concentration in the stalks of this cultivar were approximately 120 and 280 g kg-1

, respectively.

The reported fiber concentration was more than twice that of commercial sugarcane. L 79-1002

has shown promising energy characteristics, however, L 79-1002 has also shown increasing

susceptibility to smut disease (caused by Ustilago scitaminea Sydow & P. Sydow) (Bischoff et

al., 2008) in the field in LA and FL, thus new high-yielding, disease-free germplasm is needed.

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In the Everglades Agricultural Area in south Florida, where soils are primary organic

Histosols, Deren et al. (1991) tested two inter-specific hybrids between commercial sugarcane

and S. spontaneum (US 72-1288 and US 79-1010) under seasonally flooded conditions. They

reported dry biomass yields of 20 and 60 Mg ha-1

for the cultivar US 72-1288 and 7 and 42 Mg

ha-1

for the cultivar US 79-1010, in the plant cane (first-year crop) and first ratoon crops (second-

year crop), respectively.

In phosphatic clay soils, where fertility and water holding capacity are high, energycane

may be grown with minimal inputs thus reducing production costs. Stricker et al. (1993)

evaluated two energycane accessions in phosphatic clays in central Florida, and reported mean

annual dry biomass yields of 43 and 49 Mg ha-1

yr-1

, for L 79-1002 and US 72-1153 energycane,

respectively. Energycane yields increased through the 4-yr study, suggesting strong ratooning

ability.

According to Burner et al. (2009) it is important to select site-specific crop species that fit

an overall bioenergy management plan. To date, Florida and Louisiana are the largest sugarcane

producers in the U.S., having sugarcane production areas of 150,660 and 157,950 hectares,

respectively (USDA, 2009). Established sugarcane production infrastructure (planting,

fertilizing, weeding and harvesting equipment), grower experience in tall grass production, and a

favorable climate are important factors that make energycane production attractive in Florida.

Elephantgrass (Pennisetum purpureum Schum.)

Elephantgrass is a tall rhizomatous perennial bunchgrass that may reach a height of 6 m

and similar appearance to sugarcane, introduced from tropical Africa in 1913 (Thompson, 1919).

Popularly named as Napiergrass, usually propagated vegetatively and can also reproduce

sexually but seed size are small and seedlings are weak (Burton, 1993). Initially exhibited

20

potential as forage for cattle when introduced in the USA (Sollenberger et al., 1987), because of

its high biomass production, elephantgrass exhibits potential for use as a bioenergy crop.

Burton (1989) registered Merkeron elephantgrass (Pennisetum purpureum Schum.) as a

hybrid between dwarf elephantgrass, no. 208, and a tall selection, no. 1. Woodard et al (1991)

compared elephantgrass (PI 300086 and Merkeron) to energycane (L 79-1002) for silage on

sandy soils of north Florida, harvested one, two and three times per year. They reported average

dry biomass yields of 27.3, 27.0, and 17.5 Mg ha-1

yr-1

for PI 300086, Merkeron and L 79-1002,

respectively. However, biomass yields were reduced with increased frequency of harvest for all

three genotypes.

Prine et al. (1991) recorded elephantgrass dry biomass yields ranging from 20 to 30 Mg

ha-1

yr-1

in north Florida. Prine et al. (1997) also grew elephantgrass on a range of soils in

southern and central Florida using different cultural practices and reported dry biomass yields

between 30 and 60 Mg ha-1

yr-1

.

Elephantgrass is adapted to soils ranging from low-fertility acid soils to slightly alkaline

soils (Hanna et al., 2004). Elephantgrass is a C4 crop with high water use efficiency and high

biomass yields that could produce large amounts of biomass per acre, thus reducing land

requirements needed for biomass feedstocks (Lewandowski et al., 2003). However, desirable

traits for bioenergy crops may overlap with those of invasive non-native species (Barney and

DiTomaso, 2008). Elephantgrass raises concerns to sugarcane growers in south Florida, since is

commonly seen growing along canals and roadsides in sugarcane production areas (Rainbolt,

2005) and is found to have a high probability of becoming invasive (Gordon et al., 2011). Since

there are no labeled herbicide for the selective control of elephantgrass and cultural and

mechanical control less effective at the later stages of growth (Rainbolt, 2005), proper

21

management practices should be taken into to consideration when growing elephantgrass near

already established sugarcane areas.

Giant reed (Arundo donax L.)

Giant reed is a tall perennial grass species, putatively native to East Asia (Rossa et al.,

1998), with a rapid growth rate of up to 8 m within a growing season (Perdue, 1958). Giant reed

is one of the tallest of the herbaceous grasses (Lewandowski et al., 2003), and is found in all

subtropical regions of both hemispheres (Herrera and Dudley, 2003).

The Arundo genus belongs to the Poaceae family and is commonly named giant reed,

bamboo reed, Spanish reed, Italian reed, or wild cane. Despite its rapid growth rate, giant reed is

a C3 plant, although its high rates of photosynthesis and biomass productivity are similar to those

of a C4 plant (Rossa et al., 1998; Christou, 2001). Giant reed flowers in the late summer, but

apparently does not produce viable seeds. Consequently, it is planted by rhizome propagation or

vegetative planting of the stalks. Giant reed has exhibited potential for use as a bioenergy crop,

with rapid growth, low nutrient requirements, and adaptation to different soil conditions,

tolerating both heavy clays and loose sands (Perdue, 1958). According to Hartmann (2001), the

lignin and cellulose concentration of giant reed is higher than annual crops, which explains its

ability to stand upright at lower water concentrations. Thus, giant reed may be better suited to

late harvest than other biomass crops (Lewandowski et. al., 2003).

In an experiment in Italy by Angelini et al. (2009), the biomass yield of giant reed was

reported up to 42 Mg ha-1

in the plant cane crop under optimal conditions in a warm climate with

sufficient irrigation. In the first ratoon crop, biomass dry yield increased by 43% (from 29 to 51

Mg ha-1

yr-1

). Lewandowski et al. (2003) has shown that giant reed can maintain a relatively

stable biomass yield from the second to fourth ratoon crop.

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Giant reed is considered by some scientists to be a noxious or invasive plant (Gordon et al.,

2006; Barney and DiTomasso, 2008). Despite these concerns, giant reed has also been cited as a

potential biomass energy crop (Lewandoski et al., 2003; Angelini et al., 2009). The date and

location of the introduction of this species in the U.S. is unknown, but giant reed has become an

invasive weed problem in riparian areas of California and watersheds of Texas (Herrera and

Dudley, 2003). In wetlands of Florida, especially south Florida, giant reed invasive potential in

areas near Lake Okeechobee has been evaluated (Gordon et al., 2006). The risk of giant reed

becoming an invasive weed is considered low to moderate, although it has been found in 21 of

67 Florida counties. Other than its growth characteristics and its invasive ability, little is known

about appropriate management practices for large scale production of this crop, and little has

been published on its use for bioenergy production in the U.S.

23

CHAPTER 3

CROP GROWTH AND BIOMASS YIELDS FROM BIOENERGY GRASS SPECIES GROWN

ON SANDY SOILS OF FLORIDA

The growing reliance on energy, the exhaustion of fossil fuel energy sources, and

significant changes in climate are factors that drive the increasing demand for alternative energy

sources. Biomass energy sources are attractive due to their favorable carbon balance and as

renewable alternatives to existing transport fuels (Schell et al., 2004). The technology of ethanol

production from non-food plant sources is being developed rapidly for large-scale production in

the near future (Lin and Tanaka, 2006), and the production costs and species selection have been

a major concern (Cardinale et al., 2007).

According to Long (2008), ideal characteristics of a biomass crop are low input

requirements, C4 photosynthesis, long canopy duration, high water-use efficiency, ability to

manage using existing farm equipment, disease and pest resistance, ease of harvest, and storage

in the field. Successful production of cellulosic biofuel feedstocks will depend on improvement

of plant characteristics through traditional and molecular breeding methods. Other selection

criteria when breeding for cellulosic ethanol include high fiber/sugar ratio, tolerance to biotic and

abiotic stresses, high biomass yields, low or late flowering, and no grain set (Jakob et al., 2009).

Some perennial grasses have desirable attributes, including high amounts of renewable

lignocellulosic biomass, high nutrient and water use efficiency (Lewandowski et al., 2003), and

relatively inexpensive production (Kim and Dale, 2004; Bransby, 2008). These qualities have

contributed to increased interest in perennial grasses as feedstocks for biofuel production. Since

the mid-1980s, various perennial grasses have been proposed for bioenergy in temperate and

sub-tropical regions of the world. Giant reed (Arundo donax L.) (Angelini et al., 2009),

miscanthus (Miscanthus x giganteus) (Lewandowski et al., 2003; Atkinson, 2009; and Burner et

al., 2009), energycane (Saccharum spontaneum hybrids) (Wang et al., 2008), and elephantgrass

24

(Pennisetum purpureum Schum.) (Woodard and Prine, 1993; Overman and Woodard, 2006; and

Morais et al., 2009) have been evaluated for bioenergy potential in both Europe and the U.S.

The southeastern regions of the U.S., where sunlight is abundant and growing seasons are

long, is the optimum zone of the country for biomass production (USDA, 2010). The state of

Florida has favorable climatic conditions and low opportunity-cost land for production of

biomass crops, and can be considered as one of the leading areas in the United States to produce

biomass as a source of renewable energy. Identifying plants with high biomass production for

marginal lands, such as sandy soils in south Florida, is critical for the successful implementation

of cellulosic biofuels.

In the Everglades Agricultural Area in south Florida, where soils are primarily organic

Histosols, Deren et al. (1991) tested two inter-specific hybrids between commercial sugarcane

and S. spontaneum (US 72-1288 and US 79-1010) under seasonally flooded conditions. They

reported annual dry biomass yields of 20 and 60 Mg ha-1

for the cultivar US 72-1288 and 7 and

42 Mg ha-1

for the cultivar US 79-1010, in the plant cane and first ratoon crops, respectively.

In phosphatic clays soils, where fertility and water holding capacity are high, energycane

may be grown with minimal inputs thus reducing production costs. Stricker et al. (1993)

evaluated two energycane accessions in phosphatic clays in central Florida, and reported mean

annual dry biomass yields of 43 and 49 Mg ha-1

yr-1

, for L 79-1002 and US 72-1153 energycane,

respectively. Energycane yields increased through the 4-yr study, suggesting strong ratooning

ability. Giamalva et al. (1984) reported average dry weight cane yields of L 79-1002 over a five

year harvest period of 21 Mg ha-1

yr-1

in Louisiana. Brix and fiber concentration in the stalks of

this cultivar were approximately 120 and 280 g kg-1

, respectively. The reported fiber

concentration is more than twice that of commercial sugarcane. L 79-1002 has shown promising

25

energy characteristics, however, L 79-1002 has also shown increasing susceptibility to smut

disease (caused by Ustilago scitaminea Sydow & P. Sydow) in the field in LA and FL.

Elephantgrass is adapted to soils ranging from low-fertility acid soils to slightly alkaline

soils (Hanna et al., 2004). Woodard et al (1991) compared elephantgrass (PI 300086 and

Merkeron) to energycane (L 79-1002) for silage on sandy soils of north Florida, harvested one,

two and three times per year. They reported average dry biomass yields of 27.3, 27.0, and 17.5

Mg ha-1

yr-1

for PI 300086, Merkeron and L 79-1002, respectively. Prine et al. (1991) recorded

elephantgrass yields ranging from 20 to 30 Mg ha-1

yr-1

in north Florida. Prine et al. (1997) also

grew elephantgrass on a range of soils in southern and central Florida using different cultural

practices and reported yields between 30 and 60 Mg ha-1

yr-1

. In an experiment in Italy by

Angelini et al. (2009), the dry biomass yield of giant reed was reported up to 42 Mg ha-1

yr-1

in

the plant cane crop under optimal conditions in a warm climate with sufficient irrigation. In the

first ratoon crop, biomass dry yield increased by 43% (from 29 to 51 Mg ha-1

yr-1

).

While energycane, elephantgrass, and giant reed have been evaluated for biomass

production in Europe and U.S. there is a lack of information on biomass yields when grown on

marginal sandy soils in Florida. This information is crucial as this is the area where biomass

production is most likely to occur. The objectives of this study were to: 1) compare plant growth;

2) quantify fresh and dry biomass yields; and 3) quantify Brix, juice, and moisture concentration

of selected perennial grass genotypes in a two-crop cycle grown on marginal lands in Florida.

Materials and Methods

Soil and Climatic Conditions

The experiment was conducted at two mineral soil sites with differing soil organic matter

concentration. The first location, managed by Florida Crystals Corporation (Tecan), contained

soil of the Pomona series (sandy, siliceous, hyperthermic Ultic Alaquods). This soil is

26

characterized by an Ap horizon (to a depth 15-20 cm) with 50 g kg-1

organic matter

concentration, soil pH of 4.7, and Mehlich-1 extractable P, K, Ca, Mg, and Si of 6.2, 22, 847, 24,

and 1.1 mg kg-1

, respectively. The second location, managed by United States Sugar Corporation

(Townsite), also contained soil of the Pomona series. However the Townsite location had a lower

organic matter concentration of 15 g kg-1

, average soil pH of 7.3, and higher P, K, Ca, Mg, and

Si of 10.4, 31, 2515, 148, and 113.1 mg kg-1

, respectively.

The coordinates of the field boundaries for each experiment were as follows: Tecan

(26o37.84Ń, 80

o56.19´W), (26

o37.64Ń, 80

o56.19´W), (26

o37.64Ń, 80

o56.10´W), (26

o37.84Ń,

80o56.09´W); and Townsite (26

o43.95Ń, 80

o59.18´W), (26

o44.37Ń, 80

o59.18´W), (26

o44.37Ń,

80o59.23´W), (26

o43.95Ń, 80

o59.23´W).

Air temperature and rainfall were recorded by a meteorological station of the Florida

Automated Weather Network (FAWN), Clewiston, FL at a distance of 1 km from Townsite and

10 km from Tecan field trials. Average monthly maximum and minimum temperatures, as well

as precipitation during the 27-mo. period of the study are shown in Figure 3-1.

Field Experiment Design and Management

Large-scale plots were used at both locations to facilitate mechanical harvesting with

commercial equipment. Plots measured four rows wide by 12.2 m long, with 1.5 m and 1.7 m

between-row spacing, at Townsite and Tecan, respectively. The experiment was planted in a

randomized complete block design with 3 replications.

Fertilization, weed and pest control at both sites followed customary commercial sugarcane

practices. Our goal was to determine how the germplasm used in this experiment would perform

under standard field management practices and under rainfed conditions. All plots at both

locations received 150, 170, and 170 kg ha-1

of N, P2O5, and K2O, respectively, one week prior to

27

planting and 160, 160, and 170 kg ha-1

of N, P2O5, and K2O, respectively, eight weeks after plant

cane harvest.

Genotype Selection

Energycane genotypes were initially selected from wide crosses of S. spontaneum x

commercial sugarcane made at the U.S. Department of Agriculture-Agricultural Research

Service (USDA-ARS) Sugarcane Field Station at Canal Point, FL. Fifty-three of these genotypes

were planted in December 2006 in single replicate plots on a Lauderhill muck soil (euic,

hyperthermic and Lithic Haplosaprist) at the University of Florida Everglades Research and

Education Center (EREC) in Belle Glade, FL. From these 53 genotypes, 21 were selected for this

study based on superior plant cane yields at EREC.

For this present research project, only 12 genotypes from the experimental plots at Tecan

and Townsite were selected based on plant cane yields at those sites to proceed with a complete

fiber concentration, ash concentration, and higher heating value analysis for this study. From the

selected energycane genotypes, only nine were common to both sites (Tecan and Townsite), 875-

3; US 74-1010; US 78-1011; US 78-1014; US 78-1013; US 82-1655; US 84-1047; US 84-1066

(CP energycane genotypes) and giant reed. Three other genotypes were added to the selection

from the Tecan site, L 79-1002 (Bischoff et al., 2008), used as an energycane check, and

‘Merkeron’ and ‘Chinese Cross’ elephantgrass (Pennisetum purpureum Schum.). The check

cultivar, L 79-1002, was not planted at Townsite because insufficient seedcane was produced to

plant a second experiment. Elephantgrass genotypes were also not used at Townsite, because of

grower concerns regarding the weed potential of this species in adjacent sugarcane fields

(Rainbolt, 2005).

The Tecan location was planted on 19 Dec. 2007 and the Townsite location on 21 Feb.

2008. All plots were planted vegetatively using stalk cuttings from the germplasm collection at

28

EREC. The EREC seedcane was harvested at a 10-cm stubble height on the day of planting. Two

stalks were placed horizontally side by side in furrows 15 to 20-cm deep, and chopped into

sections approximately 60-cm long to remove apical dominance and improve seedcane

germination.

Measurements and Analysis

Leaf area index (LAI) for all selected genotypes was measured once per month for a

period of 9 months in the first ratoon crop (2009-2010) at Tecan on 27 Jan., 17 Feb., 17 Mar., 14

Apr., 18 May, 16 June, 16 July., 18 Aug., and 18 Sept. 2009 (41, 62, 90, 118, 152, 181, 211, 244,

and 275 days after plant cane harvest) and Townsite for a period of six months, with

measurements performed on 15 Apr., 12 May, 12 June, 20 July, 19 Aug., and 23 Sept. 2009 (34,

61, 92, 130, 160, and 195 days after plant cane harvest). A SunScan Canopy Analysis System

(Dynamax Inc., Houston, TX) was used to estimate leaf area index. This system uses a 1.0-m

wand placed beneath the crop canopy to measure transmitted photosynthetic active radiation

(PAR) and compares it to simultaneous measurements of unshaded radiation from a globe sensor

outside the plots to calculate LAI. Since the inter-row spacing of the plots was 1.5-m and the

SunScan wand is 1.0-m, two measurements were taken diagonally across the measurement row,

spanning from mid-row to mid-row, and these readings averaged to get one LAI measurement.

This procedure was repeated twice per plot, and all readings were performed between 10 and 14h

(Gilbert et al., 2008). Plant cane crop results were not conducted because LAI equipment was not

available at the time. LAI equipment failure precluded measurements after the month of

September on the first ratoon crop at Townsite.

Two days prior to final biomass yield measurements at Tecan (plant cane, 15 Dec. 2008;

and first ratoon, 13 Dec. 2009), and at Townsite (plant cane, 10 Mar. 2009; and first ratoon, 8

Mar. 2010), ten stalks were collected at random from the two center rows of each plot. These ten

29

stalk samples were chopped in a modular sugarcane disintegrator (Codistil S/A Denini, Mod:

132S, Piracicaba-SP, Brazil). All chopped plant material (including leaf, stem and tops) from

each sample was mixed in an individual 200 L barrel. From each of the plot samples, two

subsamples were collected. Subsample 1, composed of 800 to 1000 g fresh weight was used to

measure juice concentration and Brix (total soluble solids). Subsample 2, composed of 500 to

700 g of fresh weight biomass was used to measure moisture concentration.

For juice concentration, Subsample 1 fresh weight was recorded and then samples were

placed in a hydraulic press (Codistil S/A Dedini, Mod: D-2500-II, Piracicaba-SP, Brazil), for 30

sec. until pressure attained 3000 psi. The resultant filter cake press subsample was weighed and

the extracted juice, juice volume and weight were measured to determine the juice concentration

from biomass. Approximately 5 ml of juice was used to determine total soluble solids (Brix) in a

refractometer (Bellingham and Stanley Inc., RFM 91, England). Subsample 2 was placed in a

paper bag (Duro Bag Mfg., #25, Florence, KY), fresh weight was recorded using a balance with

weighing capacity up to 8100 g x 0.1 g (Metter Toledo, Mod: PB-8001-S), and the subsample

was dried at 60°C until constant weight to determine dry biomass concentration and moisture

concentration.

Plots were harvested at Tecan on 19 Dec. 2008 (plant cane) and 15 Dec. 2009 (first

ratoon). Townsite harvests occurred on 12 Mar. 2009 (plant cane) and 10 Mar. 2010 (first

ratoon). The border rows (rows 1 and 4) were removed and the center two rows of each plot were

cut using a commercial sugarcane harvester. Harvesters used at Tecan on plant cane harvest and

first ratoon were Case IH 7700 (Piracicaba, Brazil) and Case IH 8800 (Piracicaba, Brazil),

respectively, and at Townsite a John Deere 3510 model (Catalão, Brazil) was used for both crop

harvests. These harvesters were followed by a tractor (John Deere, 7210, Moline, IL) pulling a

30

weigh wagon (Cameco Ind., 3 Ton Sample Wagon, Thibodaux, LA). All primary and secondary

fans from the sugarcane harvester were turned off to ensure all harvested aboveground biomass,

including leaves and tops, was deposited into the weigh wagon. The weigh wagon was equipped

with load cells (Avery Weigh-Tronix, 715), and the two center rows of each plot were weighed

individually before taring the scale and proceeding to the following plot. Total dry biomass

yields were calculated using fresh weights recorded by the weigh wagon at harvest multiplied by

the dry biomass concentration of subsample 2.

Statistical Analysis

Data were analyzed using SAS software (SAS Inc., 1996; Littell et al., 2002). Analyses of

variance for all yield data were performed for a randomized complete block design using the

general linear model (PROC GLM) of the SAS software. LAI measurements at each sampling

date were analyzed using ANOVA with genotype as the independent variable. Mean separations

were performed using Fisher’s protected LSD (least significant difference) method at P= 0.05

unless otherwise noted. Three separate analysis were performed and are presented separately for

genotypes grown at the 1) Tecan location (875-3; US 74-1010; US 78-1011; US 78-1014; US

78-1013; US 82-1655; US 84-1047; US 84-1066; giant reed; Merkeron; and Chinese Cross), 2)

Townsite location (875-3; US 74-1010; US 78-1011; US 78-1014; US 78-1013; US 82-1655; US

84-1047; US 84-1066; and giant reed), and 3) Combined analysis (875-3; US 74-1010; US 78-

1011; US 78-1014; US 78-1013; US 82-1655; US 84-1047; US 84-1066; and giant reed) for the

common set of genotypes grown at both Tecan and Townsite. Main effects of crop and genotype

and their interactions were analyzed for the Tecan and Townsite data sites whereas main effects

of crop, genotype, site, and their interactions were analyzed for the combined data set.

31

Results

Significant differences in first ratoon crop LAI were noted beginning 75 days after plant

cane harvest at Tecan (Figure 3-2A) and Townsite (Figure 3-2B). By the final measurement date

at 275 days after harvest (DAH), LAI of the Merkeron elephantgrass and CP energycane

genotypes was significantly greater than the Chinese Cross elephantgrass and energycane

genotype L 79-1002, which was significantly greater than giant reed at the Tecan location

(Figure 3-2A). LAI of the CP energycanes was significantly greater than giant reed from 120 to

190 days after plant cane harvest (Figure 3-2B).

Tecan Analysis

At Tecan, the effects of crop and genotype were highly significant for juice concentration,

Brix, and moisture concentration, and the crop x genotype interaction was significant for Brix

(Table 3-1).

Figure 3-3 presents plant cane and first ratoon crop treatment effect means for juice

concentration (A), Brix (B), and moisture concentration (C) at Tecan. The plant cane crop had

greater means than the first ratoon crop for all three traits, with plant cane recording 424, 118,

and 648 g kg-1

greater juice concentration, Brix and moisture concentration, respectively.

The juice concentration and Brix means of 146 and 93 g kg-1

for giant reed, and 265 and

77 g kg-1

for Merkeron, were lower than the energycane genotypes. Energycane means ranged

from 386 to 427 g kg-1

for juice concentration, and 114 to 127 g kg-1

for Brix (Table 3-2). Data

for these traits were not obtained for the elephantgrass genotype Chinese Cross. All energycane

and elephantgrass moisture concentrations were higher than giant reed at Tecan (Table 3-2).

The crop x genotype interaction for Brix at Tecan (Table 3-3). The genotypes giant reed,

Merkeron, and US 78-1013 increased from the plant cane to first ratoon crops for Brix, however,

all other genotypes decreased in Brix from plant cane to first ratoon.

32

Crop and genotype had significant effects on fresh yields, however only the genotype

effect was significant for dry yields. The interaction of crop x genotype was not significant for

either trait (Table 3-4).

Figure 3-4 presents the crop treatment effect means for fresh (A) and dry yield (B) in the

plant cane and first ratoon crops at Tecan. The plant cane crop had 18.5% greater fresh yields

than the first ratoon crop, however the dry yields were similar across crops.

Fresh and dry yields for giant reed at Tecan were lower (only 10.1 and 5.3 Mg ha-1

) than

the energycane and elephantgrass genotypes (Table 3-5). Merkeron elephantgrass was notable

for high fresh and dry yields. US 74-1010 recorded lower fresh and dry yields than US 78-1013,

but in general there were few differences in yields among energycane genotypes.

Townsite Analysis

At the Townsite location, the crop and genotype effects were significant for juice

concentration, Brix and moisture concentration (Table 3-6). However, the crop x genotype

interaction was significant only for Brix.

Figure 3-5 presents plant cane and first ratoon crop means for juice concentration (A), Brix

(B), and moisture concentration (C). Juice and moisture concentrations were significantly lower

in plant cane than first ratoon at Townsite. However, Brix was significantly greater in plant cane

than the first ratoon crop.

At Townsite, the juice concentration, Brix, and moisture concentrations of giant reed

were lower than energycane genotypes (Table 3-7). Giant reed had only 77 g kg-1

juice

concentration compared to a range of 331 to 363 g kg-1

for the energycane genotypes. Thus while

the Brix values of giant reed juice concentration were 17% percent lower than the energycanes,

the total sugar yields would be much lower due to the lower total juice concentration in the plant.

33

Figure 3-6 presents the significant crop x genotype interaction means for Brix at

Townsite. Brix was greater for all energycane genotypes in plant cane than the first ratoon crop

with an average decrease of 30% between crops. In contrast, giant reed had a 13.5% increase

from the plant cane to the first ratoon crop. Crop and genotype had significant effects on fresh

and dry yields at Townsite, but the crop x genotype interaction was not significant for these traits

(Table 3-8).

Figure 3-7 presents the crop treatment effect means for fresh (A) and dry yield (B) in the

plant cane and first ratoon crops at Townsite. The plant cane crop had lower fresh and dry yields

than the first ratoon crop. Fresh yield increased 29.5 percent and dry yield increased 30.6 percent

from plant cane to first ratoon.

Fresh yields of the energycane genotypes (44.0 to 52.1 Mg ha-1

, Table 3-9), were greater

than fresh yields of giant reed (10.6 Mg ha-1

). Dry yield means of the energycane genotypes, 17.9

to 20.4 Mg ha-1

per year, were also greater than giant reed (6.0 Mg ha-1

). Fresh and dry yields

were not different among energycane genotypes.

Combined Analysis

Crop, genotype, site, and crop x site interactions had highly significant effects on juice

concentration, Brix, and moisture concentration. The crop x genotype interaction was significant

only for Brix. Thus, this analysis will focus primarily on the crop x site interaction means (Table

3-10).

The crop by genotype interaction was significant for Brix yield (Table 3-11). Giant reed

recorded an increase in Brix from plant cane to the first ratoon crop, whereas all the energycane

genotypes recorded a decrease in Brix between crops.

Figure 3-8 presents the significant crop x site interaction for juice concentration (A), Brix

(B), and moisture concentration (C). The three traits exhibited different trends across crops at the

34

two locations. Juice concentration was greater in plant cane than first ratoon at Tecan, but greater

in first ratoon than plant cane at Townsite. The opposite trend was recorded for moisture

concentration with first ratoon means greater than plant cane at Tecan but plant cane greater than

first ratoon at Townsite. Brix means were higher in plant cane than first ratoon at both locations,

however the difference was greater at Townsite than Tecan.

The effect of genotype, site and the crop x site interaction was highly significant for fresh

yield, crop, genotype and crop x site interactions were significant for dry yield. All other

interactions were not significant for either trait (Table 3-12).

Figure 3-9 presents the significant crop x site interaction effect means for fresh yield (A)

and dry yield (B). At Tecan, plant cane fresh and dry yields were greater than first ratoon, but at

Townsite, first ratoon yields were greater than plant cane.

Discussion

At Tecan, the leaf area index of the energycane clones declined after reaching peak

estimated LAI of 6.0 at 241 days after plant cane harvest. The LAI of L 79-1002 energycane,

Merkeron and Chinese Cross elephantgrass increased steadily up to 210 days after plant cane

harvest. Giant reed had a slow increase in LAI, reaching its peak LAI of only 2.8 at 241 days

after plant cane harvest. At Townsite, giant reed LAI was much lower than CP energycanes. The

low LAI of giant reed impacted photosynthesis and consequently fresh and dry biomass yields.

The average air temperature at Tecan during the initial 5 months of growth was 19.7°C

during plant cane and 18.6°C during the first ratoon crop. Total rainfall during the same period

was 252 mm during plant cane crop and only 19 mm during first ratoon crop. At Tecan, plant

cane fresh yields were greater than first ratoon. The difference between crops may be explained

by the fact that rainfall was greater during the initial period of crop establishment in plant cane

than first ratoon crop.

35

For thermal conversion, feedstock requires low moisture concentration, typically less than

500 g kg-1

, while lignocellulosic ethanol processing can utilize high moisture concentration

feedstocks (McKendry, 2002). Energycane and elephantgrass genotypes are thus more

appropriate for lignocellulosic ethanol than thermal conversion because their moisture

concentrations ranged from 600 to 667 g kg-1

. Giant reed recorded a moisture concentration of

470 g kg-1

and thus may be better suited for thermal conversion.

Low Brix is desired for lignocellulosic ethanol production. High Brix may suppress

enzymatic hydrolysis by microorganisms. When plants are subjected to drought stress, Brix

increases. At Townsite, energycane genotypes had greater Brix in plant cane compared to the

first ratoon. This occurred because rainfall was only 49 mm from 12 Nov. 2008 to 12 Mar. 2009,

prior to plant cane harvest. In contrast, higher rainfall (177 mm) occurred from 10 Nov. 2009 to

12 Mar. 2010, prior to first ratoon harvest, which likely increased moisture concentration and

decreased Brix.

Results from the combined data set, which included giant reed and CP energycane

genotypes common to both locations, showed that Brix was lower at Tecan than at Townsite.

This may be explained by the difference in soil organic matter content between locations. The

Tecan locations had 50 g kg-1

soil organic matter and Townsite only 15 g kg-1

. Higher levels of

soil organic matter mean more available water to plants, lower stress and lower Brix. Greater

available water in the soil stimulates plants to increase biomass (leaf area), and this may cause

reduction of sucrose due to the dilution effect and energy consumption.

The average dry biomass yields recorded for Merkeron and Chinese Cross elephantgrass in

this study (26.3 and 20.4 Mg ha-1

, respectively) are lower than dry biomass yields reported by

Bouton (2002) for Merkeron ranging from 27.7 to 30.7 Mg kg-1

, and elephantgrass lines tested

36

by Prine et al. (1997) ranging from 30 to 60 Mg kg-1

, in south and central Florida. These results

are approximately one third of those reported under optimal conditions by Andrade et al. (2005).

The low dry biomass yields observed for elephantgrass in this study can be explained by the low

fertility soil (sandy soil) and climatic conditions. However at Tecan, Merkeron had the greatest

yields among the genotypes evaluated in this study.

The cultivar L 79-1002 was released because of its high fiber concentration, excellent

ratooning ability and vigorous growth habit. According to Bischoff et al. (2008), L 79-1002 is

moderately susceptible to smut disease. Stricker et al. (1993) reported dry biomass yields

reaching up to 42.6 Mg ha-1

(4-yr means) when grown in a phosphatic clay soil in central Florida.

This productivity is much higher than that observed in sandy soils of our experiment (18.6 Mg

ha-1

) for the same cultivar. The results of the experiment demonstrated that CP energycanes

recorded similar yields to L 79-1002.

The overall dry biomass yields from giant reed, 3.8 and 5.1 Mg ha-1

in plant cane and first

ratoon, respectively, were lower than dry biomass yields observed in trials from southern Italy

(10.6 and 22.1 Mg ha-1

, in plant cane and first ratoon, respectively) (Cosentino et al., 2006),

northern Italy (13.0 and 37.0 Mg ha-1

, in plant cane and first ratoon, respectively) (Angelini et

al., 2005), and Spain (17.0 and 22.5 Mg ha-1

, in plant cane and first ratoon, respectively)

(Christou, 2001). One reason for lower dry biomass yields of giant reed in our study could be

related to the method of propagation. In the present study, seedcane cuttings was used rather than

rhizomes, which may explain the large gaps in rows of giant reed plots and lower LAI and

biomass yields. However, rhizome propagation for giant reed under rain-fed conditions on

marginal lands may not be economically viable for commercial biofuel production in Florida.

Our study used commercial seedcane production practices used in sugarcane cultivation and

37

giant reed performance was extremely poor in this farming system. According to Lewandowski

et al. (2003), the production of giant reed is more economical and environmentally favorable

under moderate irrigation. Our results showed that giant reed was approximately one fourth as

productive as energycane and elephantgrass genotypes. The poor performance of giant reed in

sandy soils could also be partially associated with the wide row spacing and 12-mo. harvest

frequency that followed commercial sugarcane standards, whereas plantings performed with

narrower rows (Gilbert et al., 2008) and more frequent cuttings could increase the low yields

reported in this study.

Based on yields, our results indicate that energycanes and elephantgrasses are more

appropriate bioenergy feedstocks than giant reed for marginal sandy soils of south Florida

managed under sugarcane cultivation practices. Rainfall during the establishment period is

essential for high biomass yields on sandy soils. Fresh and dry yields from new energycane

genotypes were similar to L 79-1002 energycane.

38

Table 3-1. Analysis of variance F ratios and level of significance for juice concentration, Brix,

and moisture concentration for crop and genotype effects and their interaction at

the Tecan location.

Treatment Juice Concentration Brix Moisture Concentration

Crop (C) 157.8*** 7.3** 144.0***

Genotype (G) 25.6*** 17.6*** 56.4***

C x G 0.8 2.6* 1.8

*, **, *** Significant at the < 0.05, 0.01, and 0.001 levels of probability respectively.

Table 3-2. Juice concentration, Brix, and moisture concentration for giant reed, energycane,

and elephantgrass genotypes at Tecan.

Genotype Juice Concentration Brix Moisture Concentration

________________________

g kg -1

________________________

Giant reed 463c† 93c 471f

Merkeron‡ 265b 77d 600e

L 79-1002 427a 117ab 667a

875-3 394a 119ab 627cd

US 74-1010 397a 121ab 654ab

US 78-1011 386a 127a 633cd

US 78-1013 390a 126ab 645bc

US 78-1014 392a 125a 637bc

US 82-1655 386a 127a 643bc

US 84-1047 392a 119ab 640bc

US 84-1066 395a 114b 653ab

Chinese Cross‡ 614de

LSD 0.05 45.96 10.5 19.33 † Treatment means followed by the same letter are not significantly different (P≤ 0.05).

‡ Elephantgrass (Pennisetum purpureum) genotypes.

39

Table 3-3. Crop x genotype interaction means for Brix of giant reed, energycane, and

elephantgrass genotypes at the Tecan location.

Genotype Brix

_____

g kg-1

_____

Crop PC† 1R

†

Giant reed 101 115

Merkeron 68 87

L 79-1002 122 110

875-3 124 115

US 74-1010 123 119

US 78-1011 123 121

US 78-1013 116 130

US 78-1014 131 118

US 82-1655 133 121

US 84-1047 124 113

US 84-1066 122 107

Chinese Cross † PC = plant cane; 1R = first ratoon.

Table 3-4. Analysis of variance F ratios and level of significance for fresh and dry yields

for crop and genotype effects and their interaction at the Tecan location.

Treatment Fresh Yield† Dry Yield

†

Crop (C) 24.8*** 2.6

Genotype (G) 14.2** 12.0***

C x G 0.8 0.7

*, **, *** Significant at the < 0.05, 0.01, and 0.001 levels of probability respectively. † Yields include the entire aboveground portion of the plant (stalks, tops, and dead leaves).

40

Table 3-5. Fresh and dry yields for giant reed, energycane, and elephantgrass genotypes at

Tecan.

Genotype Fresh Yield‡ Dry Yield

‡

__________________

Mg ha-1 __________________

Giant reed 10.1 d† 5.3d

Merkeron 65.8a 26.4a

L 79-1002 56.6abc 18.6bc

875-3 59.3abc 21.8bc

US 74-1010 51.7c 17.9c

US 78-1011 56.0abc 20.5bc

US 78-1013 63.1ab 22.2b

US 78-1014 52.6bc 18.9bc

US 82-1655 58.4abc 20.6bc

US 84-1047 59.4abc 21.0bc

US 84-1066 60.0abc 20.6bc

Chinese Cross 53.0bc 20.5bc

LSD 0.05 10.74 4.04 † Treatment means followed by the same letter are not different (P≤ 0.05).

‡ Yield includes the entire aboveground portion of the plant (stalks, tops, and dead leaves).

Table 3-6. Analysis of variance F ratios and level of significance for juice concentration,

Brix, and moisture concentration for crop and genotype effects and their

interaction at the Townsite location.

Treatment Juice Conc. Brix Moisture Conc.

Crop (C) 24.0*** 150.8*** 37.2***

Genotype (G) 44.1*** 2.7* 49.4***

C x G 0.6 5.1*** 1.6


41

Table 3-7. Juice concentration, Brix, and moisture concentration for giant reed and

energycane genotypes at Townsite.

Genotype Juice Concentration Brix Moisture

Concentration

_______________________

g kg-1

_______________________

Giant reed 77 b† 122b 431b

875-3 337a 146a 586a

US 74-1010 340a 146a 587a

US 78-1011 363a 144a 587a

US 78-1013 333a 149a 579a

US 78-1014 341a 143a 586a

US 82-1655 349a 153a 589a

US 84-1047 331a 150a 577a

US 84-1066 355a 143a 587a

LSD 0.05 38.79 1.55 20.95 † Treatment means followed by the same letter are not significantly different (P≤ 0.05).

Table 3-8. Analysis of variance F ratios and level of significance for fresh and dry

yields for crop and genotype effects and their interaction at Townsite.

Treatment Fresh Yield Dry Yield

Crop (C) 55.5*** 62.4***

Genotype (G) 17.6*** 13.7***

C x G 1.2 1.4


42

Table 3-9. Fresh and dry yields for giant reed and energycane genotypes at Townsite.

Genotype Fresh Yield ‡ Dry Yield

‡

_____________________

Mg ha-1 ______________________

Giant reed 10.6 b† 6.0b

875-3 46.4a 18.2a

US 74-1010 46.2a 18.2a

US 78-1011 50.2a 19.7a

US 78-1013 48.5a 19.6a

US 78-1014 47.6a 18.8a

US 82-1655 52.4a 20.4a

US 84-1047 44.0a 17.9a

US 84-1066 51.8a 20.4a

LSD 0.05 8.82 3.48 † Treatment means followed by the same letter are not different (P≤ 0.05).

‡ Yields includes the entire aboveground portion of the plant (stalks, tops, and dead leaves).

Table 3-10. Analysis of variance F ratios and level of significance for juice concentration,

Brix, and moisture concentration for crop, genotype, and site effects and their

interactions.

Treatment Juice Conc. Brix Moisture Conc.

Crop (C) 27.8*** 131.4*** 11.4**

Genotype (G) 52.3*** 7.6*** 99.7***

Site (S) 40.0*** 124.6*** 229.6***

C x G 0.2 5.9*** 0.6

C x S 117.8*** 62.6*** 134.2***

G x S 0.4 0.5 1.1

C x G x S 0.9 1.4 1.4


43

Table 3-11. Crop x genotype interaction means for Brix yield.

Genotype Brix

__________

g kg-1

__________

Crop PC† 1R

†

Giant reed 99 116

875-3 149 117

US 74-1010 146 121

US 78-1011 152 119

US 78-1013 153 119

US 78-1014 148 119

US 82-1655 160 120

US 84-1047 148 121

US 84-1066 145 112 † PC = plant cane; 1R = first ratoon

44

Figure 3-1. Monthly rainfall, maximum and minimum temperatures at Tecan and Townsite locations.

45

Townsite 1st ratoon LAI

Days after plant cane harvest

0 50 100 150 200

Lea

f a

rea

in

dex

, (L

AI)

0

1

2

3

4

5

6

7B

Arundo donax CP Energycane

Days after plant cane harvest

0 50 100 150 200 250 300

Lea

f a

rea

in

dex

, (L

AI)

0

1

2

3

4

5

6

7

8A

Arundo donax Chinese CrossMerkeron L79-1002 CP Energycane

Tecan 1st ratoon LAI

Figure 3-2. Genotype leaf area index (LAI) in first ratoon crop at Tecan (A) and Townsite (B).

Juice Concentration

Tecan: Plant Cane and First Ratoon

Crop

Plant Cane 1st Ratoon

Ju

ice

Co

nce

ntr

ati

on

, (

g k

g-1

)

0

100

200

300

400

500

Brix


Crop


Bri

x, (

g k

g-1

)

0

20

40

60

80

100

120

140

Moisture Concentration


Crop


Mo

istu

re C

on

cen

tra

tio

n, (

g k

g-1

)

0

100

200

300

400

500

600

700

800

a

b aCBA

b ab

Figure 3-3. Crop treatment effect means for juice concentration (A), Brix (B), and moisture

concentration (C) in the plant cane and first ratoon crops at Tecan. Different letters

represent significant differences among crop means (P < 0.05).

46

Dry Yield


Crop


Dry

Yie

ld (

Mg

ha

-1 )

0

5

10

15

20

25

aa

Fresh Yield


Crop


Fre

sh Y

ield

( M

g h

a-1

)

0

10

20

30

40

50

60

70

a

b

A B

Figure 3-4. Crop means for fresh yield (A) and dry yield (B) in the plant cane and first ratoon

crops at Tecan. Different letters represent significant differences among crop means

(P < 0.05).

Juice Concentration

Townsite: Plant Cane and First Ratoon

Crop


Ju

ice

Con

cen

trati

on

, (

g k

g-1

)

0

100

200

300

400

Brix


Crop


Bri

x, (

g k

g-1

)

0

20

40

60

80

100

120

140

160

180

200



Crop


Mois

ture

Con

cen

trati

on

, (

g k

g -1

)

0

100

200

300

400

500

600

700

b

a a

b

ba

A B C

Figure 3-5. Crop means for juice concentration (A), Brix (B), and moisture concentration (C) in

the plant cane and first ratoon crop at Townsite. Different letters represent significant

differences between crop means (P < 0.05).

47

Brix


Gia

nt ree

d

875-

3

US 7

4-10

10

US 7

8-10

11

US 7

8-10

13

US 7

8-10

14

US 8

2-16

55

US 8

4-10

47

US 8

4-10

66

Bri

x,

( g

kg

-1 )

0

20

40

60

80

100

120

140

160

180

200

220

240

Plant Cane

1st Ratoon

Figure 3-6. Crop by genotype interaction means for Brix in plant cane and first ratoon crops at

Townsite.

Fresh Yield


Crop


Fre

sh Y

ield

( M

g h

a-1

)

0

10

20

30

40

50

60

a

b

Dry Yield


Crop


Dry

Yie

ld (

Mg

ha

-1 )

0

5

10

15

20

25

b

aA B

Figure 3-7. Crop effect means for fresh yield (A) and dry yield (B) in the plant cane and first

ratoon crops at Townsite. Different letters represent significant differences among

crop means (P < 0.05).

48

Juice Concentration

Plant Cane and First Ratoon

Site

Tecan Townsite

Ju

ice

Con

cen

trati

on

, (

g k

g-1

)

0

100

200

300

400

500

Plant Cane

1st Ratoon

Brix


Site

Tecan TownsiteB

rix, (

g k

g-1

)

0

50

100

150

200

Plant Cane

1st Ratoon



Tecan Townsite

Mois

ture

Con

cen

trati

on

, (

g k

g-1

)

0

100

200

300

400

500

600

Plant Cane

1st Ratoon

A CB

Figure 3-8. Crop by site interaction means for juice concentration (A), Brix (B), and moisture

concentration (C) in the plant cane and first ratoon crops at Tecan and Townsite.

Dry Yield


Site

Tecan Townsite

Dry

Yie

ld, (

Mg

ha

-1 )

0

5

10

15

20

25

30

Plant Cane

1st Ratoon

B

Fresh Yield


Site

Tecan Townsite

Fre

sh Y

ield

, (

Mg

ha

-1 )

0

10

20

30

40

50

60

70

80

Plant Cane

1st Ratoon

A

Figure 3-9. Crop x site interaction means for fresh yield (A) and dry yield (B) in the plant cane

and first ratoon crops at Tecan and Townsite.

49

CHAPTER 4

FIBER CONCENTRATION, CALORIFIC VALUE, AND ASH CONCENTRATION OF

BIOENERGY GRASS SPECIES GROWN ON SANDY SOILS OF FLORIDA

The production of ethanol from lignocellulosic biomass is a promising alternative source

of energy (USDOE, 2006), with a comparative advantage over sources like corn and sugarcane

due to the abundance of lignocellulose compared to grain and sucrose combined, and the

diversity of raw materials that can be used as feedstocks. However, lignocellulosic ethanol

requires greater processing to extract fermentable sugars from feedstock.

Perennial grasses, such as elephantgrass, energycane and giant reed have been identified as

potential bioenergy feedstocks. Some authors suggest that these species can be grown on

marginal lands thus reducing land competition with food crops (Field et al., 2008), while causing

less harm to the environment by reducing greenhouse gas (GHG) emissions up to 88% (Farrell et

al., 2006). Biomass feedstocks are primarily composed of cellulose, hemicellulose and lignin.

The six and five-carbon carbohydrate components from cellulose and hemicellulose are

fermented into ethanol, whereas the lignin fraction is not fermented. Lignin is thus a byproduct

in the cellulosic ethanol process and may be used for direct combustion (Huang et al., 2009) to

produce steam, heat energy and electricity.

Lignocellulosic biomass composition may change depending on climatic conditions and

within-season plant growth patterns (Naik et al., 2010). Thus, careful characterization of biomass

feedstocks is necessary, since the chemical composition of plant cell wall will affect biomass

conversion efficiency.

For example, high nitrogen, moisture and ash concentration from feedstock reduces the

efficiency of thermo-chemical conversion (Sanderson et al., 1996). High moisture concentration

of feedstocks can negatively affect the combustion quality of biomass, because it causes ignition

problems and reduces combustion temperatures (Demirbas, 2004). Biomass heating value, also

50

called calorific value, can be defined as the higher heating value (HHV), which is the energy

concentration of biomass on a dry basis when combusted (Khan et al., 2009).

The quantification of cell polymers is also important to both lignocellulosic ethanol and

direct combustion bioenergy production systems. In the lignocellulosic conversion process, most

of the fermentable sugars are from cellulose and hemicellulose in plant cell walls, and lignin

limits the availability of these sugars for enzymatic breakdown (Chang and Holtzapple, 2000;

Laureano-Perez et al., 2005). However, in thermo-chemical conversion, feedstocks with greater

lignin concentration are desirable, because lignin has greater heating value than cellulose and

hemicellulose (Demirbas, 2005).

Heating value is reduced proportionally with increasing ash concentration in biomass

(McKendry, 2002). Many of the ash-forming elements in biomass, such as Si, Al, Fe, Ca, Mg,

Na, K, S, and P (Khan et al., 2009), can form slag in boiler tubes and result in the increase of

maintenance and operational costs (McKendry, 2002; Khan et al., 2009). Quantification of

feedstock composition, heating value and ash concentration enables calculations of theoretical

yields for conversion processes, assists with economic analysis, and provides selection criteria

for plant breeders.

The objectives of this study were: 1) to quantify and estimate concentration of cellulose,

hemicellulose, and lignin from plant biomass of giant reed, elephantgrass and energycane; and 2)

to quantify HHV and ash concentration of these genotypes grown on marginal lands in Florida.

Materials and Methods

The experimental design, planting and harvest were performed as reported in Chapter 3.

Two days prior to final biomass yield measurements at Tecan (plant cane, 15 Dec. 2008; and first

ratoon, 13 Dec. 2009), and at Townsite (plant cane, 10 Mar. 2009; and first ratoon, 8 Mar. 2010),

ten stalks were collected at random from the two center rows of each plot. These ten stalk

51

samples were chopped in a modular sugarcane disintegrator (Codistil S/A Denini, Mod: 132S,

Piracicaba-SP, Brazil). All chopped plant material (including leaf, stem and tops) from each

sample was mixed in an individual 200 L barrel. From each of the plot samples, two subsamples

were collected. Subsample 1, composed of 800 to 1000 g fresh weight biomass was used

estimate fiber concentration. Subsample 2, composed of 500 to 700 g of fresh weight biomass

was used to estimate fiber component concentrations, and measure higher heating value and ash

concentration.

Measurements and Analysis

For fiber concentration, Subsample 1 fresh weight was recorded and then samples were

placed in a hydraulic press (Codistil S/A Dedini, Mod: D-2500-II, Piracicaba-SP, Brazil), for 30

sec. until pressure attained 3000 psi. The resultant filter cake press subsample was weighed and

the estimated fiber concentration of the subsample was calculated using Eq. 1.

Estimated fiber concentration = (Initial subsample 1 weight – Filter cake press weight) /

(Initial subsample 1 weight) x 100 Eq. 1

Subsample 2 was placed in a paper bag (Duro Bag Mfg., #25, Florence, KY), fresh weight

was recorded using a balance with weighing capacity up to 8100 g x 0.1 g (Metter Toledo, Mod:

PB-8001-S), and the subsample was dried at 60°C until constant weight to determine dry

biomass concentration. After drying, subsamples were ground to pass a 1-mm screen in a Wiley-

Mill, standard model #3 (Thomas Scientific, Philadelphia, PA). These ground samples were

stored in whirlpak bags (± 300 g) at room temperature. Approximately 40 g of ground samples

were sent to a commercial laboratory (Dairy One Lab., Ithaca, NY) for wet chemistry analysis to

calculate acid detergent fiber (ADF), neutral detergent fiber (NDF), and acid detergent lignin

(ADL), following the method of Van Soest et al. (1991).

52

Simple subtraction rules are used to estimate cellulose and hemicellulose concentration

from ADF, NDF and ADL (Mandre, 2005; Hodgson et al., 2010).

ADF – ADL = cellulose Eq. 2

NDF – ADF = hemicellulose Eq. 3

Cellulose and hemicellulose were calculated using these equations and reported both as a

concentration and in Mg ha-1

on a total dry weight basis. Lignin was determined using the ADL

values directly (Van Soest et al, 1991) and reported as concentration on a total dry weight basis

and in total Mg ha-1

. Total dry biomass yields from each fiber component was calculated using

the total dry biomass yields (chapter 3) and multiplied by the concentration of each fiber

component.

The HHV from the ground dry biomass material was measured at a commercial laboratory

(Dairy One, Ithaca, NY) using an IKA C2000 basic Calorimeter System. The instrument was set

to IKA’s dynamic mode with an outer vessel temperature of 25 ºC. Analysis time was between 7

and 12 min. Dried samples were weighed into polyethylene bags. Samples were then placed in a

crucible, and ignited in an oxygen rich atmosphere in a sealed decomposition vessel where the

increase in temperature of the system was measured. The specific HHV of the sample was

calculated from the weight of the sample, the heat capacity of the calorimeter system determined

from benzoic acid calibration standards, and the increase in temperature of the water within the

inner vessel of the measuring cell, and expressed in MJ kg-1

on a dry biomass weight basis.

For determination of ash concentration from plant biomass, the laboratory analytical

procedure NREL/TP-510-42622 (Sluiter et al., 2008) was used. Results were expressed as the

concentration of residue remaining after dry oxidation at 575 ± 25 ºC (loss on ignition). All

results were reported relative to the 105 ºC oven dry weight of the sample. The procedure

53

consists of weighing a sample of 0.5 to 2.0 g, to the nearest 0.1 mg. This sample was placed in a

porcelain ashing crucible to heat the biomass sample in a muffle furnace (Thermolyne, Mod: F-

A1740, Dubuque, IA, USA) with a ramping program (furnace temperature ramp from room

temperature to 105 ºC, hold at 105

ºC for 12 min., ramping to 250

ºC at 10

ºC/min., holding at 250

ºC for 30 min., ramping to 575

ºC at 20

ºC/min., holding at 575 for 180 min., allowing

temperature to drop to 105 ºC, and holding furnace temperature at 105

ºC until samples are

removed) for 24 ± 6 h. Samples were then placed into a desiccator and cooled until constant

weight. Ash concentration was expressed as g kg-1

.

Statistical Analysis

Yield traits associated with lignocellulosic ethanol production (cellulose, hemicellulose,

and lignin concentration and dry weight yields) and direct combustion (HHV and ash

concentration) were analyzed using analysis of variance with Proc GLM in SAS with crop,

genotype, site and their interactions as independent variables. Fisher’s protected least significant

difference (LSD) test was used for comparisons of means in all statistical analysis.

Three separate analysis were performed and are presented separately by genotypes grown

at the 1) Tecan location (875-3; US 74-1010; US 78-1011; US 78-1014; US 78-1013; US 82-

1655; US 84-1047; US 84-1066; giant reed; Merkeron; and Chinese Cross), 2) Townsite location

(875-3; US 74-1010; US 78-1011; US 78-1014; US 78-1013; US 82-1655; US 84-1047; US 84-

1066; and giant reed), and 3) Combined analysis (875-3; US 74-1010; US 78-1011; US 78-1014;

US 78-1013; US 82-1655; US 84-1047; US 84-1066; and giant reed) for common set of

genotypes grown at both Tecan and Townsite as in Chapter 3.

54

Results

Tecan Analysis

At Tecan, crop and genotype effects were significant for cellulose, hemicellulose and

lignin concentration and yield with the exception of the crop effect on lignin yield (Table 4-1).

The crop x genotype interaction was significant only for hemicellulose concentration.

Figure 4-1 presents the crop effect means for cellulose, hemicellulose, and lignin

concentration (A) and dry yield (B) for plant and first ratoon crops at Tecan. There was a greater

cellulose and lignin concentration in first ratoon than plant cane, but higher concentration

hemicellulose in plant cane than first ratoon. Dry yields of cellulose were lower in the plant cane

than the first ratoon crop, but hemicellulose yields were higher in the plant cane than in first

ratoon. Lignin yields were not different between crops.

Giant reed produced significantly lower cellulose, hemicellulose, and lignin yields than

energycane and elephantgrass (Table 4-2). Merkeron elephantgrass had the highest yields for all

three traits. Elephantgrass genotypes Merkeron and Chinese Cross had higher cellulose and

lignin concentrations than most energycane genotypes, with giant reed also having higher lignin

concentration than the energycanes. The fiber components concentrations and yields were similar

among energycane genotypes.

Crop had a significant effect on ash concentration and HHV values whereas genotype did

not have a significant effect on these traits. The genotype x crop interaction effect was only

significant for HHV (Table 4-3).

The crop x genotype interaction for hemicellulose concentration and HHV at Tecan (Table

4-4). An increase in hemicellulose occurred for L 79-1002, US 78-1011, US 78-1014, US 84-

1047, and US 84-1066 from plant cane to the first ratoon crop, whereas all other genotypes

decreased in hemicellulose concentration between plant cane and first ratoon crops. Increases in

55

HHV were noted from plant cane to first ratoon for all genotypes, except Merkeron and Chinese

Cross elephantgrass.

Figure 4-2 presents the crop treatment effect means for ash concentration and HHV.

Higher heating value was greater in first ratoon (20.1 MJ kg-1

) than in plant cane (19.6 MJ kg-1

).

However, ash concentration was lower at first ratoon (219 g kg-1

) than in plant cane (313 g kg-1

).

Townsite Analysis

At the Townsite location, crop had a significant effect on cellulose and lignin concentration

and cellulose, hemicellulose and lignin yields (Table 4-5). The genotype effect was significant

for cellulose, hemicellulose and lignin yields and hemicellulose concentration. Crop x genotype

interaction effects were significant only for cellulose concentration.

Figure 4-3 presents the crop effect means for cellulose, hemicellulose, and lignin

concentration (A) and dry yield (B) for plant and first ratoon crops at Townsite. Cellulose and

lignin concentration was greater in the first ratoon than the plant cane crop, whereas

hemicellulose concentration was not different between crops. Dry biomass yields were lower in

plant cane than the first ratoon crop for all fiber components.

Giant reed yielded less cellulose, hemicellulose, and lignin yields than the energycane

genotypes (Table 4-6) due to lower total biomass rather than lower fiber component

concentrations. Giant reed had higher hemicellulose concentration than the energycane

genotypes, with the exception of US 82-1655. In general, the energycane genotypes recorded

similar fiber concentrations and yields.

Figure 4-4 presents the crop x genotype interaction effect means for cellulose

concentration at Townsite. First ratoon crop cellulose concentrations were greater than the plant

cane crop for all genotypes, however the differences were smaller for giant reed than the

energycane genotypes.

56

The crop effect was significant for ash concentration and higher heating values at

Townsite, whereas genotype and crop x genotype interaction did not have a significant effect on

these traits (Table 4-7).

Figure 4-5 presents the crop means for ash concentration (A) and HHV (B) at Townsite.

Ash concentration was greater in plant cane than the first ratoon crop, but HHV were greater in

the first ratoon than the plant cane crop.

Combined Analysis

Crop, site, and genotype had significant effects on all fiber concentrations and yields, with

the exception of the crop effect on hemicellulose concentration and the effect of genotype on

cellulose concentration (Table 4-8). The crop x site interaction effect was significant for all traits

with the exception of hemicellulose concentration. The crop x genotype interaction effect was

significant for hemicellulose concentration, the site x genotype interaction had a significant

effect on hemicellulose yield, and the crop x site x genotype interaction was significant for

cellulose concentration.

Figure 4-6 presents the site by crop interaction effect means for cellulose, hemicellulose,

and lignin concentration (A) and total yield (B) for plant cane and first ratoon crops. Cellulose

concentration and yield differences between crops were greater at Townsite than Tecan.

Similarly, differences in lignin concentration and yield between crops were greater at Townsite

than Tecan. Differing trends in hemicellulose yields between crops were noted at Townsite and

Tecan with plant cane hemicellulose yields greater than first ratoon at Tecan but first ratoon

yields greater than plant cane at Townsite.

The crop by genotype interaction was significant for hemicellulose yield (Table 4-9).

Hemicellulose yields decreased between crops for giant reed, 875-3, US 78-1013, US 78-1014,

57

and US 82-1655 energycane, but increased for US 74-1010, US 78-1011, US 84-1047, and US

84-1066 energycane.

Hemicellulose yields were markedly lower at Townsite than Tecan for 875-3, US 78-1011,

US 78-1013, and US 84-1047 energycane genotypes (Table 4-10). Giant reed and US 74-1010

recorded similar hemicellulose yields between sites.

The 3-way genotype x site x crop interaction had a significant effect on cellulose

concentration (Table 4-11). For giant reed, cellulose concentration differences between crops

were larger at Tecan (9.9 %) than Townsite (5.7 %), but for all the energycane genotypes

cellulose concentration differences between crops were larger at Townsite than Tecan.

Crop and site effects and the crop x site interaction were significant for ash concentration

and HHV (Table 4-12). Varietal effects and their interactions were not significant for these traits.

There was a crop x site interaction for ash concentration (A) and HHV (B) for plant cane

and first ratoon crops at the Tecan and Townsite locations (Figure 4-7). Ash concentration was

greater in plant cane than first ratoon at both locations, but the difference between crops was

greater at Tecan. Tecan and Townsite recorded similar HHV (B) across crops.

Discussion

This study is the first to our knowledge to characterize the cell wall components from

energycane genotypes, giant reed and Merkeron and Chinese Cross elephantgrass. Our results

showed that mean cellulose, hemicellulose, and lignin concentration (mean of plant cane and

first ratoon crops) were 400, 273, and 81 g kg-1

, respectively, across species. McKendry (2002)

reported fiber concentration means for switchgrass, ranging from 300 to 500, 100 to 400, and 50

to 250 g kg-1

, for cellulose, hemicellulose, and lignin, respectively. Our data on energycane, giant

reed and elephantgrass fall within the same range. Hodgson et al. (2010), working with

Miscanthus genotypes in Europe, reported cellulose, hemicellulose, and lignin concentrations

58

ranging from 412 to 539, 235 to 338, and 76 to 115 g kg-1

, respectively. Their data are similar to

those for giant reed, elephantgrasses, and energycanes in this study, for which cellulose,

hemicellulose, and lignin concentrations ranged from 395 to 444, 252 to 305, and 65 to 112 g kg-

1, respectively, from two locations.

According to Ingram et al. (1999), fiber concentration from grass species vary between

200 to 500 g kg-1

cellulose, 200 to 400 g kg-1

hemicellulose, and 100 to 200 g kg-1

lignin. The

average lignin concentration from the selected species in this experiment was lower than means

observed by Ingram et al. (1999). The lignin concentration of giant reed, Merkeron and Chinese

Cross elephantgrass (96, 93, and 113 g kg-1

, respectively) was higher and moisture concentration

lower (471, 600, and 614 g kg-1

, respectively) than the energycanes with overall average lignin of

77 g kg-1

and moisture concentration of 615g kg-1

. Genotypes with greater lignin concentration,

such as Merkeron elephantgrass and giant reed, could cause an inhibitory effect on enzymatic

hydrolysis, making the fermentation of cellulose and hemicellulose less efficient.

For the production of ethanol, a biomass feedstock with high cellulose/hemicellulose

concentration is needed to provide a high amount of ethanol per metric ton of biomass. To

illustrate the effect of cellulose concentration on yield, up to 280 l/t of ethanol can be produced

from switchgrass, compared with 205 l/t from wood, largely due to the increased proportion of

lignin in wood (McKendry, 2002). The energycane cellulose, hemicellulose, and lignin

concentration reported in our study (397, 272, and 77 g kg-1

, respectively) is considered adequate

for ethanol production via microbial digestion (McKendry, 2002).

Jung and Lamb (2004) reported that hemicellulose and cellulose concentrations are

overestimated and lignin underestimated using the detergent fiber system and ADL which was

used to calculate the concentrations of cellulose and hemicellulose (Eq. 1 and Eq. 2). However,

59

this method is the predominant method used by agronomists and animal scientists to measure

forage quality (Jung and Lamb, 2004), and is a much less expensive method (approximately

$30/sample) to estimate fiber concentration in bioenergy crops than NREL methods

(approximately $500/sample). NIR calibrations with NREL wet chemistry methods may reduce

the cost and processing time for bioenergy fiber analysis.

Cellulose and lignin concentration from all genotypes at both locations were higher in

first ratoon than plant cane. To our knowledge this is the first report of changes in fiber

composition across crops. This information indicates that the calorific value across crops may

increase, since lignin is positively correlated to HHV. The overall HHV of plant cane and first

ratoon crops for the species in the present study were 19.2 and 19.9 MJ kg-1

, which is similar to

overall values reported by Naik et al. (2010) for firewood biomass (19.6 MJ kg-1

) and by Hu et

al. (2010) for switchgrass (18.8 MJ kg-1

). However, Mantineo et al. (2009) found averages of

16.4 MJ kg-1

for giant reed and M. x giganteus, and 15.9 MJ kg-1

in C. cardunculus, that were

lower than the values found for the grass species in this study.

The major component of ash is silica. Ash concentration has been linked to silica (Si)

concentration in plant tissue (Crocker et al., 1998) which is also linked to soil clay concentration

(Sander, 1997). High silica concentration of feedstock can combine to cause fouling and slagging

of combustion systems when temperature exceeds the melting point of ash. The development of

low ash agricultural feedstock (< 30 g kg-1

ash) could significantly expand biofuel markets

(Samson and Mehdi, 1998). Results from our soils analysis, show a high difference on the

available Si between locations, Tecan (1.1 mg kg-1

) and Townsite (113.1 mg kg-1

). Plants grown

in soils with high Si concentration recorded high ash concentration. In the first ratoon crop,

60

Tecan with low available Si in the soil had ash concentration of 24.6 g kg-1

, and Townsite, with

high available Si in the soil had ash concentration of 31.6 g kg-1

.

The low overall ash concentration observed in the present experiment is due to the high

sand concentration linked to low Si uptake. Thus the low ash concentration observed in this

study may be due to the soil characteristics (sandy soils).

Based on the lignocellulosic characteristics, all the genotypes tested in this study, with

exception of giant reed, are promising biomass candidates to be grown under commercial

management practices in sandy soils in south Florida. The cellulose, hemicellulose, and lignin

concentrations were 400, 273, and 81 g kg-1

, respectively. Direct combustion ash concentration

appears to be related to available Si in the soil.

Merkeron elephantgrass and giant reed had lower moisture and higher lignin

concentrations than the energycane genotypes. Those species appear to be more appropriate for

direct combustion than the energycanes, whereas the energycanes would be better suited for

cellulosic ethanol production.

61

Table 4-1. Analysis of variance F ratios and level of significance for cellulose, hemicellulose,


interaction at Tecan.

Treatment Cellulose Hemicellulose Lignin

Conc. Yield Conc. Yield Conc. Yield

Crop (C) 202.1*** 4.1* 5.5* 4.4* 8.0** 0.4

Genotype (G) 3.2** 11.4*** 4.6*** 12.3*** 7.1*** 7.9***

C x G 1.4 0.9 2.8** 1.0 1.9 1.7


Table 4-2. Cellulose, hemicellulose, and lignin concentrations and yield for giant reed,

energycane, and elephantgrass genotypes at Tecan.

Genotype Cellulose Hemicellulose Lignin

g kg-1

Mg ha-1

g kg-1

Mg ha-1

g kg-1

Mg ha-1

Giant reed 413 cd† 2.2c 305a 1.6f 96b 0.5c

Merkeron 445a 11.7a 296abc 7.9a 93bc 2.5a

L 79-1002 420bcd 7.8b 283bcd 5.3cde 72d 1.3b

875-3 400d 8.7b 306a 6.7b 80cd 1.7b

US 74-1010 416bcd 7.4b 275d 4.9e 78cd 1.4b

US 78-1011 400d 8.2b 289abcd 5.9bcde 70d 1.4b

US 78-1013 408cd 9.1b 278cd 6.2bcde 69d 1.5b

US 78-1014 396d 7.4b 293abcd 5.5bcde 77d 1.4b

US 82-1655 419bcd 8.6b 301ab 6.2bcd 68d 1.4b

US 84-1047 432abc 9.0b 301ab 6.3bc 65d 1.3b

US 84-1066 417bcd 8.6b 294abcd 6.1bcde 79cd 1.6b

Chinese Cross 441ab 9.1b 252e 5.1de 113a 2.3b

LSD 0.05 24.6 1.82 20.4 1.20 14.8 0.50 † Treatment means followed by the same letter within a column are not significantly different

(P≤ 0.05).

62

Table 4-3. Analysis of variance F ratios and level of significance for ash

concentration and HHV value for crop and genotype effects and their

interaction at the Tecan location.

Treatment Ash Concentration HHV

Crop (C) 53.8*** 46.0***

Genotype (G) 1.0 0.8

C x G 1.4 2.1*

*, **, *** Significant at the < 0.05, 0.01, and 0.001 levels of probability

respectively.

Table 4-4. Crop x genotype interaction means for hemicellulose and HHV of giant reed,

energycane, and elephantgrass genotypes at the Tecan location.

Genotype Hemicellulose HHV

_____

g kg-1

_____

_______

MJ kg-1 _______

Crop PC† 1R

† PC 1R

Giant reed 340 271 19.9 20.2

Merkeron 310 282 20.1 20.0

L 79-1002 280 285 19.6 20.2

875-3 319 292 19.7 20.1

US 74-1010 275 275 19.5 20.3

US 78-1011 284 294 19.4 20.0

US 78-1013 285 270 19.8 20.0

US 78-1014 287 300 19.5 20.3

US 82-1655 310 293 19.5 20.3

US 84-1047 29.3 30.9 19.3 20.1

US 84-1066 29.4 29.4 19.5 20.3

Chinese Cross 25.5 25.0 20.2 20.0 † PC = plant cane; 1R = first ratoon.

63



interaction at Townsite.



Crop (C) 400.3*** 182.1*** 0.0 65.9*** 273.0*** 263.0***

Genotype (G) 0.5 12.5*** 2.4* 12.5*** 1.9 8.1***

C x G 2.6* 1.6 1.6 1.2 1.3 2.0


Table 4-6. Genotype effect for cellulose, hemicellulose, and lignin concentrations (conc.) and

yield for giant reed and energycane genotypes at Townsite.

Genotype Cellulose Hemicellulose Lignin


g kg-1

Mg ha-1

g kg-1

Mg ha-1

g kg-1

Mg ha-1

Giant reed 385.5 2.39b† 283.2a 1.58c 95.2 0.65c

875-3 383.8 7.14a 247.8bc 4.55ab 81.8 1.54ab

US 74-1010 372.3 6.89a 258.3bc 4.68ab 82.0 1.53ab

US 78-1011 380.2 7.60a 243.0c 4.75ab 80.2 1.62ab

US 78-1013 390.2 7.83a 253.0bc 4.96ab 82.8 1.69ab

US 78-1014 383.3 7.29a 254.8bc 4.79ab 82.8 1.63ab

US 82-1655 375.8 7.80a 266.2ab 5.42a 79.0 1.66ab

US 84-1047 385.8 7.19a 248.7bc 4.36b 76.0 1.47b

US 84-1066 384.2 8.18a 250.0bc 5.14ab 85.8 1.86a

LSD 0.05 23.7 ns

1.42 22.4 0.92 11.1 ns

0.35 † Treatment means followed by the same letter are not significantly different (P≤ 0.05).

ns = not significant at P=0.05.

Table 4-7. Analysis of variance F ratios and level of significance for ash concentration

and HHV for crop and genotype effects and their interaction at the Townsite

location.


Crop (C) 10.1*** 123.5***


C x G 0.6 1.4


64


and lignin concentration (conc.) and total yield for crop, site, and genotype effects

and their interaction.



Crop (C) 561.6*** 142.1*** 1.5 19.6*** 152.6*** 148.6***

Genotype (G) 1.1 31.5*** 2.9** 31.2*** 4.5** 13.8***

Site (S) 54.4*** 11.3** 104.8*** 42.4*** 10.2** 5.0*

C x G 1.0 1.3 3.8*** 0.9 0.9 1.3

C x S 15.5*** 55.7** 2.1 44.7*** 44.3*** 81.5***

G x S 1.2 0.9 1.6 2.2* 0.9 0.5

C x G x S 2.2* 0.9 0.8 0.6 1.1 1.8


Table 4-9. Crop x genotype interaction means for hemicellulose yield.

Genotype Hemicellulose

__________

Mg ha-1 __________

Crop PC† 1R

†

Giant reed 32.25 26.60

875-3 27.88 27.45

US 74-1010 26.63 26.73

US 78-1011 25.77 27.43

US 78-1013 27.13 25.93

US 78-1014 36.87 27.93

US 82-1655 28.75 28.00

US 84-1047 27.28 27.68

US 84-1066 26.82 27.57 † PC = plant cane; 1R = first ratoon.

65

Table 4-10. Genotype x site interaction means for hemicellulose yields of giant

reed and energycane genotypes.

Genotype Hemicellulose

________

Mg ha-1 ________

Tecan Townsite

Giant reed 1.61 1.58

875-3 6.65 4.55

US 74-1010 4.92 4.68

US 78-1011 5.90 4.75

US 78-1013 6.15 4.96

US 78-1014 5.50 4.79

US 82-1655 6.03 5.42

US 84-1047 6.31 4.36

US 84-1066 6.08 5.14

66

Table 4-11. Genotype x site x crop interaction means for cellulose concentration of giant reed

and energycane genotypes

Genotype Site Crop Cellulose

g kg-1

Giant reed TC† PC

‡ 363

1R‡ 462

TS† PC 354

1R 411

875-3 TC PC 354

1R 446

TS PC 317

1R 450

US 74-1010 TC PC 387

1R 445

TS PC 310

1R 435

US 78-1011 TC PC 365

1R 435

TS PC 312

1R 439

US 78-1013 TC PC 378

1R 445

TS PC 335

1R 445

US 78-1014 TC PC 359

1R 433

TS PC 341

1R 425

US 82-1655 TC PC 377

1R 461

TS PC 321

1R 430

US 84-1047 TC PC 392

1R 472

TS PC 331

1R 441

US 84-1066 TC PC 377

1R 457

TS PC 325

1R 443 † TC= Tecan; TS= Townsite

‡ PC = plant cane; 1R = first ratoon.

67

Table 4-12. F ratios and level of significance for ash concentration and HHV for

crop, site, and genotype effects and their interaction.


Crop (C) 49.3*** 180.1***


Site (S) 10.4** 173.5***

C x G 0.6 1.5

C x S 8.0** 4.9*

G x S 0.5 0.4

C x G x S 0.4 1.0


Cellulose, Hemicellulose, and Lignin Total Yield


Cellulose Hemi. Lignin

Dry

Bio

mass

Yie

ld, (

Mg h

a -1

)

0

2

4

6

8

10

Plant Cane

1st Ratoona

b

ab

aa

Cellulose, Hemicellulose, and Lignin Concentration


Cellulose Hemi. Lignin

Con

cen

trati

on

, (

g k

g-1

)

0

100

200

300

400

500

Plant Cane

1st Ratoon

a

b a

b

ab

A B

Figure 4-1. Crop means for cellulose, hemicellulose, and lignin concentration (A) and dry yield

(B) at Tecan. Different letters represent significant differences among crop means (P

< 0.05).

68

Ash Concentration


Crop


Ash

Co

nce

ntr

ati

on

( g

kg

-1 )

0

50

100

150

200

250

300

350

400

a

b

Higher Heating Value


Crop


Hig

her

Hea

tin

g V

alu

e (

MJ

kg

-1 )

0

2

4

6

8

10

12

14

16

18

20

22

24

ab

A B

Figure 4-2. Crop treatment means for ash concentration and higher heating value at Tecan.

Different letters represent significant differences between crop means (P < 0.05).



Fiber Component

Cellulose Hemi Lignin

Co

nce

ntr

ati

on

, (

g k

g-1

)

0

100

200

300

400

500

Plant Cane

1st Ratoon a

b

a

b

a a



Cellulose Hemi Lignin

To

tal

yie

ld,

( M

g h

a -1

)

0

2

4

6

8

10

Plant Cane

1st Ratoon

a

ba

b

b

a

Fiber Component

A B

Figure 4-3. Crop effect means for cellulose, hemicellulose, and lignin concentration (A) and dry

yield (B) at Tecan. Different letters represent significant differences between crop

means (P < 0.05).

69

Cellulose


Genotypes

Gia

nt r

eed

875-

3U

S 74

-101

0U

S 78

-101

1U

S 78

-101

3U

S 78

-101

4U

S 82

-165

5U

S 84

-104

7U

S 84

-106

6

Cel

lulo

se, (

g k

g-1

)

0

50

100

150

200

250

300

350

400

450

500

550

600

Plant Cane

1st Ratoon

Figure 4-4. Crop x genotype interaction means for cellulose concentration in the plant cane and

first ratoon crops at Townsite.

70

Ash Concentration


Crop


Ash

Co

nce

ntr

ati

on

, (

g k

g-1

)

0

5

10

15

20

25

30

35

40

a

b




Hig

h H

eati

ng

Va

lue,

( M

J k

g-1

)

0

2

4

6

8

10

12

14

16

18

20

22

24

ab

A B

Figure 4-5. Crop treatment effect means for ash concentration (A) and HHV (B) in plant cane

and first ratoon crop at the Townsite location. Different letters represent significant

differences between crop means (P < 0.05).



Cel

lulo

se T

C

Cel

lulo

se T

S

Hem

i. TC

Hem

i. TS

Lig

nin T

C

Lig

nin T

S

Tota

l Y

ield

, (

Mg h

a-1

)

0

2

4

6

8

10

Plant Cane

1st Ratoon

B



Cel

lulo

se T

C

Cel

lulo

se T

S

Hem

i. TC

Hem

i. TS

Lig

nin T

C

Lig

nin T

S

Con

cen

trati

on

, (

g k

g-1

)

0

100

200

300

400

500

Plant Cane

1st Ratoon

A

Figure 4-6. Crop x site interaction effect means for cellulose, hemicellulose, and lignin

concentration (A) and total yield (B) in the plant cane and first ratoon crops at Tecan

(TC) and Townsite (TS).

71

Ash Concentration


Site

Tecan Townsite

Ash

Co

nce

ntr

ati

on

, (

g k

g-1

)

0

5

10

15

20

25

30

35

40

45

50



Site

Tecan Townsite

Hig

h H

eati

ng

Va

lue,

( M

J k

g-1

)

0

5

10

15

20

25

30

Plant Cane

1st Ratoon

A BPlant Cane

1st Ratoon

Figure 4-7. Crop x site interaction effect means for ash concentration (A) and HHV (B).

72

CHAPTER 5

SUMMARY AND CONCLUSIONS

Our results indicate that energycanes and elephantgrasses are more appropriate bioenergy

feedstocks than giant reed for marginal sandy soils of south Florida. Rainfall during the

establishment period of growth is essential for high biomass yields on sandy soils. Fresh and dry

yields from new energycane genotypes were similar to L 79-1002 energycane.

Based on the lignocellulosic characteristics, all the genotypes tested in this study, with

exception of giant reed, are promising biomass candidates to be grown under commercial

management practices in sandy soils in south Florida. The cellulose, hemicellulose, and lignin

concentrations averaged 400, 273, and 81 g kg-1

, respectively (overall average).

Merkeron and giant reed had higher lignin concentration than energycane genotypes.

Those species are more appropriate for combustion than the energycanes. The feedstock ash

concentration appears to be related to available Si in the soil.

Future Research Needs

Because energy crops are more likely to be grown on marginal lands, such as the sandy

soils used for this study, and expected to be grown under minimal inputs, the ratooning ability

and nutrient uptake of perennial grasses under these stress conditions should be further addressed

in order to select bioenergy feedstocks for upcoming commercial-scale biofuel plants in Florida.

73

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BIOGRAPHICAL SKETCH

Pedro H. Korndörfer was born in 1984 in Porto Alegre, RS, Brazil. Pedro developed his

interests in agriculture from a family business producing sugarcane rum, and by following in his

father’s footsteps, a professor in plant nutrition. He earned his B.S. degree in Agronomy in 2008

from Goiás State University, Ipameri, GO, Brazil. Pedro began his experience at University of

Florida through short-term scholar programs in the fall of 2005, 2007 and 2008, participating in

sugarcane, weed science, and bioenergy crops research programs with Drs. Gilbert, Rainbolt and

Helsel, respectively. He joined the Agronomy Department at the University of Florida in spring

2009, pursuing his graduate studies under the supervision of Dr. Robert A. Gilbert and

completed his master’s degree program in spring 2011.

biomass and energy yields of bioenergy...

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