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|Accumulation of peat|
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|Inventory of peat in Florida|
|Everglades agricultural area|
|Industrial uses of peat|
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|Endangered species associated with...|
|Reclamation of mined peatlands|
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Division of Natural Resources
Unnumbered ( 3 )
Table of Contents
Historical perspective of peat research in Florida
Accumulation of peat
Accumulations of peat in Florida
Inventory of peat in Florida
Everglades agricultural area
Industrial uses of peat
Potential environmental impacts of peat mining
Endangered species associated with areas of potential peat mining
Reclamation of mined peatlands
Summary and conclusions
Appendix A: Federal environmental legislation
Appendix B: Classification of wetlands in Florida
AppendixC: Florida statutes concerning wetlands
Appendix D: Water quality
Appendix E: Peatlands management
cpE Fi ~eufr -4
AN OVERVIEW OF PEAT
AND RELATED ISSUES
Secretary of State
RALPH D. TURLINGTON
Commissioner of Education
ELTON J. GISSE
GERALD E .iLEW IS
Commissioner' of a oricuiture
The cover drawing shows Water:Lilly (Nymphaea), the living
plant from which Water Lilly Peat ',ot s, characteristiic of,,.';
relatively deep, open waters '
r ~-~':: ~~I~II ~' I ""
STATE OF FLORIDA
DEPARTMENT OF NATURAL RESOURCES
Elton Gissendanner, Executive Director
DIVISION OF RESOURCE MANAGEMENT
Charles W. Hendry, Jr., Director
BUREAU OF GEOLOGY
Steve R. Windham, Chief
AN OVERVIEW OF PEAT
AND RELATED ISSUES
Bureau of Geology
Paulette Bond, Principal Investigator
THE FLORIDA LEGISLATURE
TABLE OF CONTENTS
Executive Summary. ................ ... .................... x
Acknowledgements.... .. d........ ............ .............. xviii
Purpose and Scope of the Study .............. ............. 1
Historical Perspective of Peat Research in Florida......... 1
Definition of Peat and the Significance of This
Definition ... .. ............... .... ........... ......... 4
Terminology Relating to the Peat Forming Environment.. 7
Peat: Agricultural or Mineral Resource?.............. 9
Harvesting or Mining ................................. 14
Classification Systems Applied to Peat ................ 16
The Accumulation of Peat... .... ..... ....... ... ............. 20
The Process of Peat Formation......................... 20
Geologic Conditions Associated with Peat
Accumulation ...................................... 21
Mining Technology .......... .............................. 23
Mining Methodology Associated with the Use of
Peat for Fuel................................. .. .. 23
Mining Methodology Associated with the
Agricultural Use of Peat ........................... 26
The Accumulation of Peat in Florida...................... 27
Rates of Peat Accumulation in Florida................. 27
Geologic Settings of Peat Accumulation in Florida..... 30
Inventory of Peat in Florida............................... 40
Mapping and Evaluating the Peat Resource.............. 40
Current Estimates of Peat in Florida.................. 42
The Everglades Agricultural Area.......................... 49
History of the Everglades Agricultural Area........... 49
Crops and Soils of the Everglades Agricultural Area... 51
Subsidence ............................................ 54
Conservation Measures. .......... . ............. 60
The Near Future of the Everglades Agricultural Area... 61
Industrial Uses of Peat .... ...... ........................ 65
Preparation of Peat for Industrial Utilization........ 65
Fuel Uses ............................................. 67
Direct Combustion ............................... 67
Gasification ................. ... ........ ........ 68
Biogasification .................................. 69
Industrial Chemicals... ............................... 70
Bitumens. ........... ............................ 70
Carbohydrates. ........................... ....... 72
Humic Acids ........ ...... ...................... 73
Peat Coke, Peat Tar and Activated Carbon......... 74
Use of Peat as a Growth Medium ............. .......... 75
Horticulture .......... .... ... ... ................ 75
Agriculture..... .............................. 76
Energy Crops ........... ........................ 76
Sewage Treatment. ....................................... 77
Economic Impact........................... .......... ..... 78
Production, Value, and Price of Peat.................. 78
Location of Peat Producers ........... ....... .......... 80
Location of Markets... ............................... 82
Use of Peat.................................. .. ........ 82
Permitting ................................................. 83
County Level Permits ... .............................. 83
State Level Permitting .............................. ..... 86
Department of Environmental Regulation........... 86
Water Management Districts....................... 87
Suwannee River Water Management District.... 87
St. Johns River Water Management District... 87
Southwest Florida Water Management
District ........................ ....... 93
South Florida Water Management District..... 94
Department of Community Affairs.................. 94
Federal Level Permitting............................... 95
Army Corps of Engineers.......................... 95
The Environmental Protection Agency............... 96
Peat Revenue and Taxation................................... 96
Potential Environmental Impacts of Peat Mining............. 98
The Effects of Peat Mining on Wetlands................ 98
The Effects of Peat Mining on Water Quality............ 102
The Effects of Peat Mining on Water Resources......... 107
Water Resources in an Undisturbed System......... 107
Water Resource Parameters Affected by Peat
Mining ........ ..... ........ ....... ........
The Effects of Peat Mining on Air Quality .............
The Effects of Peat Mining on Topography .............
Endangered Species Associated with Areas of Potential
Peat Mining............... .. .. ...........................
Reclamation of Mined Peatlands.............................
Peatland Reclamation in Minnesota.....................
Peatland Reclamation in North Carolina.......... .....
Peatland Reclamation in Finland........................
Peatland Reclamation in New Brunswick.................
Reclamation in Peatlands of Florida...................
Summary and Conclusions........................ ...... .....
Glossary of Technical Terms............................. ...
Appendices ...................... .......... ...............
Appendix A. Federal Environmental Legislation........
Appendix B. Classification of Wetlands in Florida....
Appendix C. Florida Statutes Concerning Wetlands......
Appendix D. Water Quality............................
Appendix E. Peatland Management......................
The process of coal formation...................
The relationship of peat types to fuel grade.....
A comparison of moisture content and heating
value for peat, wood and various coal types....
4 Peat provinces of southern Florida............... 31
5 SW-NE cross-section from Cape Sable to vicinity
of Tamiami Trail ....... .......... ... ........... .. 32
6 Cross-section through a cypress hammock...c...... 33
7' Cross-section through a "Bay Head"............... 34
8 Cross-section through bay swamp and titi swamp... 35
9 Peat deposits bordering lakes.................. 36
10 Cross-section showing peat filling lake.......... 37
11 Cross-section using cores to show buried peat
layers at Eureka Dam site, Oklawaha River,
Marion County, Florida........................ 38
12 Isopach map of the Everglades region showing
thickness of peat and some muck areas........... 41
13 Peat deposits in Florida......................... 45
14 Fuel grade peat deposits in Florida.............. 46
15 Peat deposits in Florida........................ 47
16 Location map of the Everglades Agricultural
17' Map of the Everglades Agricultural Area showing
the locations of profiles A-A' and B-B'........ 57
18 Profile A-A' across the upper Everglades showing
the original surface elevations and the
ground elevation in 1940 as shown by
topographical survey. Profiles for the years
1970 and 2000 are estimated .................... 58
19 Profile B-B' through the lower part of the
Everglades Agricultural Area show the original
surface elevation and the surface elevation as
determined in 1940 by topographic surveys.
Profiles for the years 1970 and 2000 are
estimated...... ............ ................. 59
20 Soil depths predicted (Stephens and Johnson,
1951) for the year 1980. Compare with
figure 17: ..................................... 62
21 Thicknesses of soils from the Everglades
Agricultural Area as determined in a recent
study .......................................... 63
22 Location of current peat producers............... 79
23 Production and value of peat in Florida.......... 81
24 Topographic profile of a karst basin peat
deposit in north Florida ...................... 119
25 Topographic profile of St. Johns River Marsh
peat deposit in southern Brevard County........ 120
26 Topographic profile of the Oklawaha River peat
deposit in northern Lake-southern Marion
counties ....................................... 121
27 Topographic profile of the Santa Fe Swamp peat
deposit in Alachua and Bradford counties....... 122
28 Topographic profile of the Everglades in Collier
and Dade counties............. ..... ...... .... 124
1 Estimated rates of peat accumulation in
Florida ......... ................... .......... 28
2 Proportions of the organic soils of the
Everglades Agricultural Area falling into
categories based on thickness.................. 64
3 Summary of county level permitting
requirements .. ............................... 84
4 Water quality issues associated with peat
mining ......................................... 104
5 Water resources issues associated with peat
6 Air quality issues associated with peat mining... 115
7 Plant communities of concern ..................... 128
8 Endangered, threatened, and rare species
associated with areas of potential peat
accumulation ................................... 129
9 Independent factors governing site specific
reclamation programs........................... 138
Peat is a deposit of partially decayed plant remains which
accumulates in a waterlogged environment. It may contain some
proportion of inorganic material which is referred to as ash.
Ash content is a critical parameter if peat is to be used as a
fuel and may not exceed 25 percent of the material by dry weight.
In addition, fuel grade deposits must be at least four feet thick
with a surface area of at least 80 contiguous acres per square
mile. Fuel grade peat must yield at least 8000 BTU per moisture-
Peat is removed from the ground in an excavation process.
The procedure is alternatively referred to as harvesting or
mining. "Harvesting" when used in conjunction with peat
correctly refers to the nearly obsolete practice of harvesting
Living Sphagnum from the surface of a bog. In this process, the
Sphagnum was allowed to grow back so that repeated harvests were
possible in a given area. Very little or no true harvesting
occurs today. Thus, the extraction of peat is properly termed
An important implication of the definition of peat is its
classification as an agricultural resource as opposed to a
mineral resource. This classification may have ramifications
with respect to the sorts of regulations which are applied to
peat mining. Peat does not comply with the conditions set forth
in the academic definition of the term mineral. It is, however,
considered a mineral resource by the United States Geological
Survey and the United States Bureau of Mines. Peat is an
ancestor of the mineral graphite and is also viewed by earth
science professionals as nonrenewable. Thus it is considered
appropriate to term peat a mineral resource.
Peat-accumulates and is preserved in wetlands, such as the
Everglades, marshes and mangrove swamps, river-valley marshes
(St. Johns river-valley marsh), and in sinkhole lakes. This
strong association of peat with wetlands occurs because the
presence of water serves to inhibit the activity of decomposing
organisms which would normally metabolize plant matter and
prevent its accumulation.
Earth science professionals consider peat to be
nonrenewable. In Florida an average rate of peat accumulation
is 3.62 inches per 100 years. Using this average rate, a deposit
4 feet thick (minimum thickness of a fuel grade deposit) could
accumulate in approximately 1,326 years or approximately 18 human
lifetimes (average lifetime of 7'2 years).
Florida is estimated as having 677,688 acres of fuel grade
peat or 606 million tons. This estimate is based on material
thought to contain no more than 25 percent ash. Other estimates
are much greater (1.7'5 billion tons and 6.9 billion tons). These
estimates include organic soils whose ash content exceeds ASTM
standards for material defined as peat and U.S. Department of
Energy standards for fuel grade peat.
The Everglades Agricultural Area was delineated based on
scientific analysis of soils to determine their suitability as a
growth medium. The drainage necessary for successful agriculture
has been accompanied by subsidence primarily because soils are no
longer protected from decomposing organisms which require oxygen
for their metabolizm. Soil loss continues to occur at about 1
inch each.year. It is predicted that by the year 2000
approximately 250,000 acres in the Agricultural Area will have
subsided to depths of less than one foot. The fate of soils less
than one foot thick is uncertain. They may be used for pasture
land or abandoned for agricultural purposes.
Peat currently is used in Florida for a variety of
horticultural and agricultural purposes. The United States
Bureau of Mines reports that in 1982, 120 thousand short tons was
produced at a value estimated at 1.5715 million dollars. These
data reflect voluntary information supplied to the Bureau of
Mines and do not include responses from all of Florida's peat
producers. Most peat sales in Florida are currently wholesale
and for agricultural purposes and are thus exempt from sales tax.
Records are not maintained which detail sales tax on retail sale
of peat products specifically, and thus there is no way of esti-
mating the current tax income derived from the exploitation of
peat resources in the State of Florida.
The peat permitting process as it applies to peat mining is
complex. County level permits may be required, although in many
cases zoning regulations are the only regulations which apply to
opening a peat mine. At the state level, the Department of
Environmental Regulation and Water Management Districts
containing peat may require permits. The Department of Community
Affairs has jurisdiction over Developments of Regional Impact
(DRI). Certain peat mining operations could come under federal
jurisdiction. The agencies concerned would include the
Environmental Protection Agency and the Army Corps of Engineers.
The environmental impacts associated with peat mining for
energy purposes depend strongly on the size of the prospective
operation. Environmental impacts are also extremely site
specific. Small operations would consume 26 acres of peat mined
to a depth of 6 feet, over 4 years, moderate operations 3500
acres mined to a depth of 6 feet, over a 20 year period and a
large operation would require 125,000 acres of peat, mined to a
depth of 6 feet to operate for 20 years. Peat mining will occur
largely in wetlands and the functions of each individual wetland
must be weighed against the value of peat to be removed. The
wetland habitat will be severely affected. Fauna will be
displaced and possibly destroyed and flora will be destroyed when
the peatland is cleared for mining. Water quality impacts may
be major, even for small operations and are related to chemical
characteristics of the discharge waters. Water resource
parameters are not expected to be severely affected by small
scale operations but may be more seriously impacted by larger
scale development. The impacts of mining on air quality arise
from mining, processing, and utilizing peat as a fuel. They are
specific to an operation's size, mining method, and the intended
use for the product. Endangered species, both plant and animal,
may inhabit peatlands. The change in habitat brought about by
peat mining might lead to the destruction of members of stressed
species associated with a mined area.
Research in Minnesota, North Carolina, Finland and New
Brunswick, Canada, show that reclamation techniques can be
successfully applied to peatlands. Reclamation techniques are
specific to those areas and do not address difficulties inherent
to Florida peatlands. Reclamation of Florida's peatlands will
involve a change from wetland systems to other systems (probably
aquatic systems). Restoration of mined peatlands (for the most
part wetlands) will, in all probability, be financially
SUMMARY AND CONCLUSIONS
Mineral Versus Non-Mineral
Peat, like coal, petroleum and natural gas, does not comply
with the principal conditions set forth in the academic defini-
tion of the term mineral. Peat represents an early stage in a
series of products resulting in the conversion of vegetable
matter to pure carbon (peat-lignite-coal-graphite), the end pro-
duct of which fits all the requirements of a true mineral. In
classifying peat as a mineral or non-mineral, there has been a
tendency toward allowing use to play an important role in the
classification, that is, if used as an agricultural product peat
would be treated as a non-mineral or if used as an energy source
or fossil fuel peat would be treated as a mineral. Classifica-
tion based on use can create considerable confusion especially
with mineral products used as fertilizers. Peat has been
historically classified by the U.S. Bureau of Mines and the U.S.
Geological Survey as a mineral resource, a somewhat broader
category than just "mineral," along with coal, oil and natural
gas. Peat is generally regarded as nonrenewable by earth science
professionals, requiring in excess of 1,000 years to generate a
commercially extractable deposit of fuel grade peat.
This study would conclude that because of peat's genetic
relationship to the mineral graphite, its general classification
by the U.S. Bureau of Mines and the U.S. Geological Survey as a
mineral resource, and emphasizing its nonrenewability, peat
should be classed as a mineral, mineral resource, or mineral pro-
duct. Consequently, any classification based on use should be
Harvesting versus Mining
Harvesting and mining have been used synonymously to refer
to the extraction of peat. Literature searches reveal the term
harvesting correctly refers to the nearly obsolete practice of
selectively removing living Sphagnum from the surface of the bog.
In this practice, Sphagnum was allowed to grow back, permitting
successive harvests in a single location. Peat (unlike living
Sphagnum) is considered nonrenewable and the term harvesting is
inappropriate when applied to peat extraction. Additionally, the
method and equipment utilized in peat extraction and the environ-
mental impacts of peat extraction are synonymous with those com-
monly attributed to mining, not harvesting.
This.study would conclude that harvesting should be applied
only to the removal of living Sphagnum or other living plants and
that the extraction of peat should be categorized as mining.
Environmental Impacts of Peat Mining
Peat occurrence in Florida is, in nearly every case exa-
mined, coexistent in and beneath a current wetland area. For
this reason, peat mining and wetland mining are virtually synony-
mous terms in Florida. The environmental impacts associated with
peat mining may vary widely depending on the type of wetland, the
location of the wetland, the function of the wetland, the extent
of mining, the type of mining, and other physical parameters of
This study would conclude that an accurate assessment of the
environmental impacts of peat extraction will be site specific
and can be anticipated to range from minor to severe.
Reclamation of Peat Mining
Reclamation or the return of mined land to a beneficial use
is applicable to most mining operations and would be so with peat
mining. Restoration or the return of mined land to the pre-
mining function is only partially applicable to most mining
operations and would not be practical with peat mining. The
higher the ratio of overburden to the mined product, the higher
the percentage of original landform and contour that can be
achieved in reclamation. In peat mining, where the mined product
typically-has no overburden, the extraction leaves a void space
with no material available for filling, and therefore, no origi-
nal landform and contour can be achieved in reclamation.
This study would conclude that reclamation of mined
peatlands to a beneficial use as an aquatic or uplands system is
achievable, however, the restoration of mined peatlands to pre-
mining contour and function is not feasible.
Agricultural Use of Peat
The inplace use of peat and related organic for agri-
cultural purposes such as the Everglades Agricultural Area appear
to be a nonconsumptive use of peat. In fact, the exposure of
peat to air allows aerobic bacteria to oxide the peat causing a
gradual loss of peat accompanied by subsidence of the land sur-
face. It is predicted that by the year 2000, approximately
250,000 acres in the Everglades Agricultural Area will have sub-
sided to depths of less than one foot.
This report would conclude that agricultural uses of inplace
peat be viewed as a consumptive use of peat and that companion to
the use, research and planning be carried out to determine the
systems impact resulting from peat loss and land subsidence for
management to better transition into future land uses.
The initial outline for this study was read and improved by
David Gluckman, representing the Florida Chapter of the Sierra
Club; Charles Lee, representing the Florida Audubon Society; and
Katherine Ewel, Helen Hood, John Kaufmann, and Marjorie Carr,
representing the Florida Defenders of the Environment.
Richard P. Lee, Florida Department of Environmental Regulation
offered helpful comments on the outline and sent valuable
references concerning wetlands. Irwin Kantrowitz, United State
Geological Survey read the outline and offered assistance.
Ronnie Best of the Center for Wetlands, University of Florida
provided an excellent perspective on the values attributed to
wetlands and proved to be a most useful reference. Roy Ingram,
Professor of Geology at the University of North Carolina, Chapel
Hill, provided work space, access to his personal collection of
peat reference works and the benefit of his research experience
through numerous informal conversations concerning various
aspects of peat.
PURPOSE AND SCOPE OF THE STUDY
This study was undertaken in response to a directive from the
Florida Legislature originating in the Natural Resources
Committee of the Florida House of Representatives. Florida is
currently faced with immediate expanding industrial interest in
the exploitation of its peat resources for fuel use. The study
is primarily a compilation of literature pertinent to peats of
Florida and their use for agriculture and energy applications.
It is conceived as providing an information base for decisions
concerning both the utilization and conservation of Florida's
extensive peat resource.
HISTORICAL PERSPECTIVE OF PEAT RESEARCH
Interest in Florida's peat deposits has fluctuated since the
Florida Geological Survey published a "Preliminary Report on the
Peat Deposits of Florida" in its Third Annual Report (Harper,
1910). This early work was basically a reconnaissance study of
peat resources in the state. The author acknowledged that as
population density in the state increased a detailed report would
be required. In light of current environmental awareness, it is
especially interesting that Harper (1910) recommended studies by
both an engineer and an ecologist.
The historical perspective of peat use in Florida is not
complete without mention of the work of Robert Ransom, a civil
engineer, who came to Florida from Ipswich, England in 1884.
Ransom viewed Florida's peat deposits as a readily exploitable
resource and was especially interested in energy production from
peat. For thirty-five years Ransom experimented with peat, even-
tually even opening a test plant near Canal Point (Palm Beach
County) which produced power gas, tars, oils, methyl alcohol and
various by-products. He was not able to gain acceptance for his
radical projects within his lifetime (Davis, 1946).
In 1946, John H. Davis published The Peat Deposits of
Florida, Their Occurrence, Development and Uses. This study
categorized peat-forming environments in the state and treated
individual deposits in detail. It extended Harper's work and
included chemical characterization of various Florida peats.
Chemical characteristics were related to the use of peat for
agricultural purposes and also to its use as a fuel source.
A number of studies treating the peats of south Florida have
been prepared by W. Spackman in conjunction with co-workers.
Spackman and others (1964) presented a summary of various coal
forming environments associated with the Everglades. This work
includes a large number of geologic cross sections which document
the relationship of peats to bedrock and surrounding materials.
The plant communities currently associated with peats in the
various coal forming environments are also carefully documented.
Cohen and Spackman (1977', 1980) present detailed descriptions of
peats from southern Florida along with discussions of their ori-
gin, classifications and consideration of the alteration of plant
material. Spackman and others (1976) present an updated and
augmented edition of the original guidebook. The format of
these works (Spackman, et. al., 1964 and Spackman, et. al., 1976)
makes them particularly useful to scientists in various disci-
plines whose interests converge on the various wetland environ-
ments of south Florida.
In 1979, the U. S. Department of Energy began its "Peat
Development Program." The assessment of fuel grade peat deposits
was part of an effort to define energy resources in the United
States exclusive of petroleum. The Florida Governor's Energy
Office subcontracted with the University of Florida's Institute
of Food and Agricultural Sciences to survey the peat resources of
Florida. This study resulted in a literature survey of peat
deposits of Florida combined with detailed work in the Everglades
Agricultural Area (Griffin, et al., 1982).
The current study was undertaken in response to a directive
from the Florida Legislature originating in the Natural Resources
Committee of the Florida House of Representatives. It provides a
compilation of information concerning the location and amount of
Florida's peat resources. In addition, the various aspects of
the Everglades Agricultural Area are described in some detail and
implications of subsidence of peats in this region are con-
sidered. Emphasis is also placed on existing information rela-
tive to potential effects of peat mining on Florida's
environment. Legislation which may be applied to peat mining,
water quality parameters monitored in conjunction with various
phases of peat mining and methods of regulation applied to the
peat resource by Minnesota, New Brunswick and North Carolina are
included as appendices to this report.
DEFINITION OF PEAT AND THE SIGNIFICANCE OF THIS DEFINITION
Peat is defined by workers in a variety of disciplines
(geology, botany, soil science, and horticulture among others).
These definitions proliferate in response to the specific
interest of researchers and also in response to the multiple uses
of peat. The American Geological Institute defines peat as, "An
unconsolidated deposit of semicarbonized plant remains of a
watersaturated environment, such as a bog or fen and of per-
sistently high moisture content (at least 7'5 percent). It is
considered an early stage or rank in the development of
coal..." (Gary, et al., eds., 1974). This extremely general
definition notes several essential points. Peat is composed of
plant remains which accumulate in a wet environment. It is con-
sidered to be an early product of the coal-forming process.
In a definition which will be published in an upcoming
volume (A. Cohen, personal communication, 1984), the American
Society for Testing and Materials (ASTM) defines peat as a
naturally occurring substance derived primarily from plant
materials. Peat is distinguished from other organic soil
materials by its lower ash content (less than 25 percent ash by
dry weight IASTM Standards D2974]) and from other phytogenic
material of higher rank (i.e. lignite coal) by its lower BTU
value on a water saturated basis. This very specific definition
is designed so that peats may be classified objectively and
distinguished from both organic soils and also coals.
Griffin and others (1982) note the definition of fuel grade
peat which is used by the United States Department of Energy.
Fuel grade peat is defined as an organic soil consisting of
greater than 75 percent organic matter in the dry state. In
order for a peat deposit to be classified as fuel grade, the
deposit must be at least 4 feet thick, with a surface area of not
less than 80 contigous acres per square mile and yield not less
than 8000 BTU per pound (moisture free). The definition for fuel
grade peat establishes minimum standards for organic matter con-
tent and also for heating value (BTU per pound). It further com-
ments on the deposits itself, stipulating minimum thickness and
contiguous acreage requirements.
The three definitions of peat presented here respond to the
specific purposes of individuals and agencies who prepared them.
Varied user groups and professionals who work with peat may for-
mulate additional definitions directly suited to their needs. It
is thus necessary to determine the way in which an author defines
peat in order to fully understand the implications of his work.
In the state of Florida, the definition of peat may take on
special significance if it is used as criteria for classification
of peat as either a mineral resource or an agricultural
(vegetable) resource. It has been argued that if peat is not
classified as a mineral then its excavation might constitute a
harvesting process. Harvesting may not be subject to the regula-
tory procedures that govern mining of a legally-defined mineral
The usage of the term harvesting to describe the mining of
peat follows Kopstein (1979). "Harvesting" when used in conjunc-
tion with peat correctly refers to the nearly obsolete practice
of harvesting living Sphagnum (peat moss) from the surface of a
bog. In this process, the Sphagnum was allowed to grow back so
that repeated harvests were possible in a given area. Thus, a
crop was in actuality "harvested." Very little or no true har-
vesting occurs today (A. Cohen, personal communication, 1984).
In the carbonization process, the carbon content of the
plants' cellulose is proportionally increased as water, carbon-
dioxide and methane are evolved. Carbonization can be generally
described by the following equation:
072H120060 = C62H72024 + 2CH4 + 8C02 + 20H20
Cellulose Peat Methane Carbon Dioxide Water
The expressions for cellulose and peat were taken from U.S.
Geological Survey Bulletin 7'28 (Soper and Osbon, 1922).
Two major considerations arise from the definition of peat.
One of these considerations involves the classification of peat
as a vegetable or mineral and the second consideration follows
from the first. If peat is viewed as being a vegetable material,
then its excavation might be termed a harvesting process.
Harvesting practices would not be subject to the regulatory pro-
cedures that govern mining of a legally-defined mineral material.
TERMINOLOGY RELATING TO THE PEAT FORMING ENVIRONMENT
Peat can only accumulate in a waterlogged environment. The
terms which refer to these environments take on different defini-
tions according to author preference. The American Geological
Institute distinguishes between bogs and fens on the basis of
chemistry. Bogs and fens are both characterized as waterlogged,
spongy groundmasses. Bogs, however, contain acidic, decaying
vegetation consisting mainly of mosses while fens contain alka-
line, decaying vegetation, mainly reeds (Gary, et al., eds.,
1974). The terms "bog" and "fen" are not usually applied to
peatlands in the southeastern United States. They are included
in this discussion because they occur frequently in the litera-
ture associated with peatlands extraneous to Florida. Although
a significant body of research specific to the peats of Florida
exists (Cohen and Sparkman, 1980; Cohen and Spackman, 1977;
Griffin et al., 1982 Spackman et al., 1976), much information
concerning mining techniques, reclamation methods and hydrologic
aspects of peatlands pertains directly to areas remote to Florida
where the terms "bog" and "fen" may be used.
The concepts of minerotrophy and ombrotrophy are based on
the quality of water feeding a peatland (Heikurainen, 1976) and
are perceived as separate from the series eutrophy, mesotrophy
and oligotrophy. The latter series describes nutrient resources
of peatlands using plant composition with eutrophy being richer
in nutrients and oligotrophy being poorer. The eutrophy oli-
gotrophy series is difficult to apply since it may be expanded to
include additional extreme and transitional groups. The boun-
daries between these various groups are not clear (Heikurainen,
1976) and they will not be considered further in this document.
Bogs are said to be ombrotrophic, which implies that the bog
is isolated from the regional groundwater system and receives its
moisture mainly from precipitation. Minerotrophic peatlands, or
fens, are defined as being connected with the regional ground-
water system and are nourished both by precipitation and ground-
water flow (Brooks and Predmore, 1970).
The U.S. Department of Energy in its Peat Prospectus avoids
the usage of fen and characterizes peat as forming in swamps,
bogs and saltwater and freshwater marshes (Kopstein, 1979). The
extent of this confusion becomes clear on examination of the
American Geological Institute's definition of swamp (Gary, et
al., sds., 1974) which is characterized as "A water saturated
area..., essentially without peatlike accumulation." It should
be noted that most workers in the field do not concur with the
portion of the American Geological Institute's definition that
addresses the accumulation of peat in swamps (A. Cohen, personal
communication, 1984). Moore and Bellamy (1974, p. 84) use the
term "mire" to cover all wetland ecosystems in which peat
accumulates in the same area where its parent plant material
lived and grew. Thus, the meaning of specific names assigned to
the peat-forming environment must be derived from an author's
In the southeastern United States, the most commonly used
terms for.peat-forming environments are swamps and marshes.
Swamps refer to forested wetlands and marshes refer to aquatic,
herbaceous wetlands (A. Cohen, personal communication, 1984).
PEAT: AGRICULTURAL OR MINERAL RESOURCE?
In Florida, peat may eventually be viewed as a mineral
resource or an agricultural resource. The United States Bureau
of Mines has long considered peat a mineral resource for the
reporting of commodity statistics. In deference to the formal
definition of the term "mineral," the greatest majority of earth
science professionals would not classify peat as a mineral. Peat
more properly might be likened to a rock in that it contains a
number of minerals (quartz, pyrite, and clay minerals among
others) as well as macerals which are the organic equivalents of
If, however, the formal and most restricted definition of
mineral is compared with a definition of mineral that reflects
current usage, it is noted that "minerals" adhere to the specifi-
cations of the formal definition in varying degrees. The intent
of this discussion is not to establish that peat is a mineral,
but rather to illustrate the extent to which the formal defini-
tion has been expanded in the realm of common usage.
A standard mineralogy textbook for university students,
Elements of Mineralogy (Mason and Berry, 1968), gives the
following definition of a minerals "A mineral is a naturally
occurring, homogeneous solid, inorganically formed, with a defi-
nite chemical composition and an ordered atomic arrangement."
This definition is useful because its authors continue by
expanding on each part of their definition, taking into account
the complexity of the group of compounds classified as minerals.
According to this definition, a mineral must be naturally
occurring. This eliminates materials which are synthesized in
the laboratory or are formed as by-products of various manufac-
turing processes. Since peat is indisputably naturally
occurring, this aspect of the definition will not be considered
A mineral must also be a homogeneous solid. This qualifica-
tion eliminates liquids and gases from consideration and implies
that a mineral cannot be separated into simpler compounds by any
physical means (Mason and Berry, 1968). In the coalification
process by which plant material (i.e., cellulose) becomes peat,
water, carbon dioxide and methane are evolved with time
(Kopstein, 1979). Kopstein (1979) is referring to a generali-
zation of the peat-forming process in which all initial plant
material is referred to as cellulose. In actuality, peat con-
tains many types of plant material and may possibly contain no
cellulose at all. It is important here to note that many mineral
substances evolve water or gaseous by-products when subjected to
changed conditions of pressure or temperature. Gypsum dehydrates
(evolves water) forming anhydrite. The mineral talc evolves
water and forms enstatite and quartz at elevated temperatures.
Thus, minerals commonly contain water as an integral part of
their crystal structures.
The term mineral is restricted by definition (Mason and
Berry, 1968) to refer to inorganically formed substances. It
eliminates homogeneous solids formed by plants and animals such
as oyster shells, pearls and gallstones. Ostensibly, this
qualification could eliminate peat from consideration.
The American Geological Institute in its Glossary of Geology
(Gary, et al., eds., 1974) includes the following reference in
its definition of the term mineral: "A mineral is generally con-
sidered to be inorganic, though organic compounds are classified
by some as minerals." Thus, organic compounds are not automati-
cally eliminated from consideration as minerals. This suggests
that'the term mineral has come to be used in a sense that is less
restricted than might be supposed from examination of the defini-
tion presented to beginning students of mineralogy.
Minerals are defined as having definite chemical composition
(Mason and Berry, 1968). This implies that their composition
must be readily expressible using a chemical formula. It does
not preclude variation in chemical composition. Variation within
definite limits is allowed, thus, the composition is definite but
not fixed (Mason and Berry, 1968). The compositions of cellulose
and the peat derived from it are frequently cited using the
appropriate chemical formulae (Soper and Osbon, 1922, pp. 6-7;
Kopstein, 1979, pp. 5-6; Cameron, 1973, p. 506). (As noted pre-
viously, the formulae cited here are based on a generalization of
the peat-forming process in which peat is derived from a
starting material of cellulose. For most peats, this simplified
approximation is not realistic.)
The last criterion in the definition of a mineral is that of
an ordered atomic arrangement; that is, a mineral should be a
crystalline solid. Mason and Berry (1968) note a group of com-
pounds which are considered minerals even though the crystalline
state is not initially attained: "A few minerals, the commonest
being opal, are formed by the solidification of a colloidal gel
and are noncrystalline initially; many such minerals become
crystalline during geologic time." The mineral opal may attain
an ordered atomic arrangement only in the course of geologic
The coal-forming process is illustrated in figure 1. As
organic matter (originally deposited as peat) is subjected to
conditions of increasing temperature and pressure it undergoes
the changes associated with coalification. The end-product of
this process is the mineral graphite (Press and Siever, 1974,
p. 468). Graphite crystallizes in the hexagonal system and its
formula is simply carbon (C). It is found in a number of
occurrences including metamorphosed coal beds (Quinn and Glass,
ABUNDANT VEGETATION ADAPTED TO SWAMPY CONDITIONS
OVERLYING SEDIMENTARY ROCKS I
-UNDERLYING SEDIMENTARY ROCKS "
l i I
-- - -~~ --- - - -
-'- HUNDREDS TO THOUSANDS
........... OF M TERS ...........
.::::::::::OF METERS OF.-
z--OVERLYING SEDIMENTARY ROCKS
la- .- ,
I OR BITU C
Plant litter accumulates at
Buried plant litter decays
partially and is compacted
Underlying sediments in -rida
typically consist of limestone
clay and unconsolidated sand.
With shallow burial peat is
compressed to form brown
Additional burial transforms
the brown coal to lignite if
burial is comparatively shallow
and bituminous coal if depth of
burial is greater.
Coal is metamorphosed to anthracite
or graphite with continuing burial
The process of coal formation. (Modified from Press and Siever,
1974, Figure 13-18, p. 468)
I L __
-- I ,, = I
1958). The parallels with the case of opal seem apparent.
Neither opal nor peat initially attain the internal atomic
ordering referred to in Mason and Berry's definition of a
mineral. Opal will presumably achieve internal atomic ordering
in the course of geologic time (Mason and Barry, 1968). The
transformation of peat into the mineral graphite requires, in
addition to the passage of time, increases in temperature and
pressure (Press and Siever, 1974).
Geologists do not universally include crystalline form as a
prerequisite to classification of a material as a mineral. This
is demonstrated in the continuation of the AGI Glossary's defini-
tion of mineral. "Those who include the requirement of
crystalline form in the definition of a mineral would consider an
amorphous compound such as opal to be a 'mineraloid'" (Gary, et
al., eds., 1974).
The United States Geological Survey in its volume entitled
United States Mineral Resources (Brobst and Pratt, eds., 1973),
devotes a chapter to peat as well as chapters to petroleum,
natural gas and coal. The United States Bureau of Mines also
considers peat to be a mineral resource in addition to coals,
petroleum and natural gas. These resources including peat are
HARVESTING OR MINING
Harvesting and mining are both terms which are applied to
the extraction of peat. As was discussed in the section of this
report "The Definition of Peat and Significance of this
Definition" the term "harvesting" properly refers to the
practically obsolete procedure of literally harvesting living
Sphagnum from the surface of a bog. In this procedure, Sphagnum
is allowed to continue its growth subsequent to harvesting (A.
Cohen, personal communication, 1984).
Currently, the choice of "harvesting" as opposed to "mining"
for terms to describe the excavation process of peat is
arbitrary. The nature of the distinction is demonstrated in the
following quotation taken from Peat Prospectus: "Thus, the reco-
very of peat is a surface mining or harvesting process,"
(Kopstein, 1979, p. 18). It may be significant that surface
mining carries with it certain negative environmental connota-
tions. Harvesting is largely free of environmentally negative
connotations but this is perceived to be due to a lack of
understanding since harvesting is frequently used as synonymous
with surface mining.
The equipment utilized in the peat removal process is not
associated with harvesting in its commonly accepted sense. Peat
operations which are currently active in Florida utilize earth
moving and excavating machinery. In drained bogs such machinery
commonly includes shovels, bulldozers and front-end loaders
while draglines, clamshells and dredges are used in undrained
bogs (Searls, 1980).
Harvesting originally referred to removal of living Sphagnum
which was allowed to replenish itself after harvesting. Peat is
not considered renewable due to its slow rate of accumulation
(Kopstein, 1979; Moore and Bellamy, 197'4).
The process of harvesting in its usual sense does not imply
the necessity of extensive land reclamation. However, reclama-
tion of peatlands which have been excavated is acknowledged as
necessary.(Minnesota Department of Natural Resources, 1981) and
is discussed more thoroughly in the section of this report
entitled "Reclamation of Peatlands of Florida."
CLASSIFICATION SYSTEMS APPLIED TO PEAT
Peat, like many materials, is classified for the convenience
of persons using it. Since peat use in the United States has
been largely agricultural, most classification schemes are based
on properties of peat pertinent to agricultural applications. As
one might expect, classification schemes devised for agricultural
application do not necessarily indicate peat quality for energy
purposes. However, there is a general relationship between peat
decomposition and its energy value with respect to direct com-
bustion. This is illustrated in figure 2.
The American Society of Testing and Materials (ASTM) has
established maximum and minimum particle sizes for peat (ASTM,
1969). They additionally specify fiber content requirements for
various types of peat. The maximum particle size for fibers is
0.5 inch (1.25 cm) and the minimum is 0.006 inches (0.15 mm).
Peat is subdivided into five types and each type must contain a
0 10 20 30 40 50 60 70 80 90 100
PLANT FIBER DECOMPOSITION (%)
Figure 2. The relationship of peat types to fuel grade. (Modified from
certain percentage of the characteristic fiber. These percen-
tages are based on an oven-dried weight at 105 OC as opposed to
volume. The types of peat recognized by the ASTM include: 1)
Sphagnum moss peat which must contain 66.66 percent Sphagnum
fibers by weight, 2) Hypnum moss peat which must contain 33.33
percent fibers with one-half of those identifiable as Hypnum
moss, 3) reed-sedge peat which must contain 33.33 percent fibers,
half of which are reed-sedge and other nonmosses, 4) peat-humus
must contain less than 33.33 percent fiber, and 5) other peat,
which accounts for all peat not previously classified in ASTM
Designation D-2607-69 (ASTM, 1969).
The ASTM classification as discussed in the previous
paragraph is currently under revision. Two major factors were
considered in this revision. The classification of peat should
meet the needs of three major user groups including engineers,
energy users and agricultural users. In addition, the
classification should be based on parameters which may be
measured objectively. These parameters include ash, botanical
composition, pH, and water holding capacity. In order to be
called peat, a material will have to contain 75 percent or more
organic material. Although peats will still be categorized as
fibric, hemic or sapric, these general terms will be modified by
ash content, botanical composition, pH and water holding capacity
(A. Cohen, personal communication, 1983).
One essential parameter that is characteristic of all peat
is moisture level, but there are no current regulated standards
for moisture in peat. The United States Bureau of Mines con-
siders a commonly accepted value in the United States to be 55
percent moisture by weight for air dried peat (Searls, 1980).
The U.S. Department of Agriculture divides peat into three
categories (Searls, 1980). Fibric peat must contain more than
66.66 percent plant fibers. Hemic peats are more decomposed than
fibric peats. They must have a fiber content which ranges
between 33.33 percent and 66.66 percent fibers. Sapric peat con-
sists of the most extensively decomposed plant material. Sapric
peat contains less than 33.33 percent recognizable plant
fragments of any type.
Peat in the United States has often been classified into
three general categories (Searls, 1980; Kopstein, 1979). Moss
peat comprises Sphagnum, Hypnum and other mosses. Reed-sedge
peat is mainly the product of reeds, sedges and other swamp
plants. Humus is simply too decomposed for evidence of its ori-
gin to be retained.
The parameters which bear most directly on peat's usefulness
as a fuel source are measured by proximate analysis. In this
procedure, peat is analyzed in the laboratory for its volatile
content, fixed carbon, ash content and moisture. The volatile
content of peat refers to substances other than moisture which
are emitted as gas and vapor when peat is burned. Peat has a
very high volatile content compared to coal. This is a positive
attribute for peat which is to be gasified since the reactivity
of peat in the gasification process increases with increased
volatile content. The fixed carbon content of the peat is
responsible for much of its combustion energy.
Ash is the amount of material in a fuel which remains after
combustion. The amount of ash varies for different types of
peat. Peats which receive their moisture primarily from precipi-
tation are usually lower in ash than those which are nourished by
surface waters. In times of flood, surface waters may carry
large sediment loads onto the peatlands where it is trapped in
Peat's high moisture content can be a major problem which
must be considered in its utilization. Even a drained and soli-
dified bog may contain 70-95 percent moisture and for some uses
peat will require additional drying which will, in turn, require
THE ACCUMULATION OF PEAT
THE PROCESS OF PEAT FORMATION
Peat forms when the rate of accumulation of plant matter
exceeds the rate at which decomposing organisms metabolize it.
The conversion of fresh plant material to peat takes place over
a period of time as peat becomes enriched in fixed carbon while
evolving water, carbon dioxide and methane (Kopstein, 1979).
Peat is comparatively increased in fixed carbon as opposed to
cellulose and the process by which this takes place is referred
to as carbonization. It is this enrichment of carbon which makes
peat desirable as a fuel source (figure 3). The Peat Prospectus
(Kopstein, 1979) compares peat with wood and various grades of
coal in terms of fixed carbon and the heating value (in British
Thermal Units, BTU). The following values are taken from figure
3 of the Peat Prospectus and are approximate (Kopstein, 1979).
One pound-of wood with a fixed carbon content of approximately 20
percent, generates 9,300 BTU on a moisture and mineral free
basis. An equivalent amount of peat containing 28 percent fixed
carbon may generate approximately 10,600 BTU. These values for
peat and wood contrast with values for lignite which yields about
12,400 BTU at a fixed carbon content of approximately 47' percent.
These figures demonstrate that peat is a material distinguishable
from wood in its fuel-producing characteristics.
GEOLOGIC CONDITIONS ASSOCIATED WITH PEAT ACCUMULATION
As was previously noted, peat forms when the accumulation of
plant material exceeds its destruction by the organisms which
decompose it. Since plant matter is usually decomposed before
significant accumulations develop, it is instructive to examine
the set of circumstances which allow peat to form. Certain
geologic, hydrologic and climatic conditions serve to inhibit
decomposition by organisms. Ideally, areas should be continually
waterlogged, temperatures generally low and pH values of asso-
ciated waters should be low (Moore & Bellamy, 1974). It should
noted that Moore and Bellamy (1974) primarily treat peats asso-
2i 40 .
A comparison of moisture content and heating value for peat, wood
and various coal types. (Modified from Kopstein, 1979)
ciated with northern cold climates.
Certain geologic characteristics are associated with
waterlogged surface conditions. The tendency toward waterlogging
is enhanced if topographic relief is generally low and topographic
barriers exist which restrict flow and allow water to pond.
Additionally, waterlogging is encouraged if highly permeable
bedrock is covered with material of low permeability (Olson, et
The chemical nature of the plant litter may also serve to
reduce its susceptibility to decomposition. Moore and Bellamy
(1974) note the association of cypress and hardwood trees with
peats characteristic of the hammocks or tree islands of the
Everglades. These hammocks occur on peat deposits which are
situated on limestone bedrock. The trees, which are responsible
for the peat beneath them, contain enormous amounts of lignin.
Lignin is very resistant to decay (Moore and Bellamy, 1974). It
is alternatively suggested that hammock peats in Florida may be
controlled by the persistence of water (A. Cohen, personal com-
MINING METHODOLOGY ASSOCIATED WITH THE USE OF PEAT FOR FUEL
Recently, several potential commerical users have been
investigating Florida's peat as a fuel source. This interest is
prompted by the rising cost of traditional fuels. Preliminary
proposals for the use of peat as a fuel in Florida suggest that
peat will be air dried and burned directly. This usage will
require comparatively large amounts of peat which must be dried
before it is burned (this drying is in addition to the moisture
reduction which accompanies bog drainage) (Kopstein, 1979). The
drainage of a peatland is an integral and necessary first step in
any large-scale peat mining operation utilizing milled peat or
sod peat mining methods. Moisture must be reduced to approx-
imately 90 percent for the bog to be considered workable (i.e.,
able to bear the weight of machinery).
Drainage is accomplished by construction of a system of
ditches and waterways which are designed to capture water and
route it away from the portion of the bog to be mined (Kopstein,
1979). If surface streams traverse the bog, they are diverted
around it. Eventually, surface vegetation and stumps must be
There are several mining methods in common use in Europe.
The manual method is one in which peat is cut into blocks by
hand, removed from the bog for air drying and finally burned for
home heating and cooking (Kopstein, 1979). Manual peat har-
vesting is labor intensive and probably will not become important
The sod peat mining method is one in which a trench is cut
into a previously prepared field. These trenches are cut by
excavator/macerators which are specifically designed to cut,
macerate, and extrude sods onto a conveyor which deposits them
onto the field for air drying. At a moisture content of about
75 percent the sods are windrowed. Windrows are periodically
split and turned to facilitate drying and at about 55 percent
moisture sods are considered dry and removed for storage
The milled peat mining method is one in which a peat layer
1/4 to 2 inches thick is milled or shredded from the prepared
surface of the bog. The peat is periodically harrowed to
expedite drying. At a moisture content of 50 to 55 percent, the
dried peat is pushed into ridges where it is collected for
transportation to storage facilities (Aspinall, 1980).
Several methods of hydraulic peat mining are in development.
Examples of these processes are the slurry ditch, hydro peat and
slurry pond methods (Aspinall, 1980). In each of these methods,
the surface must be cleared; but drainage is not necessary.
The slurry ditch and hydro peat methods utilize high
pressure water guns to cut peat from a ditch face. The dif-
ference between the methods lies in the post-mining dewatering
process. The slurry ditch method utilizes a dewatering
apparatus; whereas, the hydro peat method is dewatered by pumping
the slurry to a drying field where it spread to dry (Minnesota
DNR, 1981). The slurry pond method utilizes mechanical
excavators or a dredge to remove peat. Mining equipment is
mounted on a barge which floats on a pond excavated within the
peat deposits as the mining progresses.
The ultimate success of wet mining methods will depend on
the successful development of very large scale dewatering
processes and upon the environmental impacts of the mining
process (Kopstein, 1979). These may be the preferred methods,
however, in areas where drainage of the peat deposit will be
MINING METHODOLOGY ASSOCIATED WITH THE AGRICULTURAL USE OF PEAT
In order to obtain current information on Florida's active
peat operations for the present study, the staff of the Bureau of
Geology designed and conducted a survey of producers. In the
first stage of this survey, a list of peat producers was
compiled. In an effort to make this list as comprehensive as
possible, a number of sources were consulted including: existing
lists of producers (Florida Bureau of Geology, United States
Bureau of Mines, United States Mines Safety and Health
Administration); agencies contacting peat producers in
conjunction with regular professional services (county
agricultural agents, Florida Department of Agriculture); and
numerous telephone directories. In the second stage of the
survey, peat producers were contacted by telephone and field
visits were arranged. The information which follows was
contributed on a voluntary basis by producers'who were contacted
during field visits.
Peat extraction methods vary with the size and nature of the
deposit being mined. Most deposits are mined using conventional
types of earth-moving and excavating equipment. The machinery
used includes draglines, backhoes, grade-alls, front-end loaders
and hydraulic excavators. The majority of companies use a
dragline for mining. A shredder is used to pulverize the peat.
Most-companies drain the immediate area of mining by
pumping and ditching, which enables the deposit to be mined by
dry processes. Approximately one-third of the companies con-
tacted conduct all or part of their mining below the watertable.
Two companies utilize a variety of the milled peat mining
process. After surface clearing and ditching is complete, the
surface peat is pulverized with a rotovater. The pulverized
material is dried in the sun and is turned by discing to help
promote drying. The dried material is mechanically windrowed
using a front-end loader or bulldozer and is then stockpiled or
loaded for transport. There are no companies currently mining
peat by the sod peat method in Florida.
ACCUMULATIONS OF PEAT IN FLORIDA
RATES OF PEAT ACCUMULATION
Knowledge of the rate of peat accumulation is important in
that it allows various extractive uses for the resource to be
weighed in light of the amount of time it takes for the material
to accumulate. Rates of peat accumulation are usually deter-
mined using the carbon-14 method of dating organic materials.
This method is subject to a number of difficulties when applied
to peat. The following problems are enumerated by Moore and
Bellamy (1974). 1) Wide errors may be introduced since young
roots may penetrate material at depth. This problem could result
in apparently rapid rates for the accumulation of peat. 2) Older
layers are compacted as new ones are deposited. This could cause
rates of deposition to appear anomalously low. 3) Rates of peat
formation vary with climate and climate varies with time. Thus,
an accumulation rate probably reflects a sort of average rate for
some given amount of peat. Several estimates of peat accumulation
rates in Florida are presented in Table 1.
TABLE 1. ESTIMATED RATES OF PEAT ACCUMULATION IN FLORIDA
Author Estimated Rate Comments
Davis (1946, p. 74) 5.2in/100 years This rate is computed based on the
amount of Si02 fixed by a standing crop
of sawgrass from the Everglades. It
is widely quoted, but a recent analysis
of the method (Gleason, et al., 1974)
indicates that certain of the assump-
tions necessary to the calculation must
be in error. This difficulty is dis-
cussed more completely in the accom-
Kuehn (1980, p. 49) 4.24in/100 years This rate was computed from a core
which penetrated peat formed alter-
nately in marine, brackish and fresh
water environments from southwest
Florida. The computations were based
on radiocarbon ages.
Kuehn (1980, p. 49) 3.64in/100 years This rate was computed for a single
type of peat, red mangrove (Rhizophora),
from southwest Florida using measured
thickness and radiometric ages.
Stephens (1974, 3 in/100 years Rates were computed from the Everglades
p. 356) using radiocarbon ages which were not
specifically referenced in the text.
The variation in rate presented here for peat accumulation
may be attributed to a number of factors. Gleason and others
(1974) used Davis' (1946) data to compute a value of productivity
for the sawgrass environment. Productivity refers to the amount
of dry organic matter (measured in pounds) which is formed on an
acre of ground in a year. When this productivity is compared to
the dry weight of an acre-foot of peat as estimated by Davis
(1946), a discrepancy is apparent. According to these com-
putations, more material accumulates as peat than is originally
formed in the sawgrass environment (Gleason, et al., 1974).
Factors which may account for this difficulty include possible
low estimates of productivity and inadequate estimates of silica
content or peat density. It is also possible that silica in the
peat might not be entirely derived from sawgrass (Gleason, et
al., 1974). Rates of peat accumulation computed from radiocarbon
age are grouped about an average of 9.1 cm/100 years. The rate
of peat accumulation can vary with climate (which also varies
with time), the position of the water table and nutrient supply
(Moore and Bellamy, 1974). Data are not available which would
allow rate variation in different environments to be evaluated.
The rates presented here were calculated from peats produced from
varying plant communities which thrive in different environments.
In addition, peat has been lost by fire during various
prehistoric dry periods (Cohen, 1974). Failure to recognize
evidence of fire could alter the rate at which peat is calculated
GEOLOGIC SETTINGS OF PEAT ACCUMULATION IN FLORIDA
The conditions under which peat can occur in Florida are
highly variable. While geologic and hydrologic relations of peat
to its neighboring materials have been thoroughly documented in
the Everglades of south Florida, numerous small deposits in the
central peninsula remain unmapped. Davis (1946, p. 114), con-
sidered the peat deposits of Florida as falling into a number of
groups based on their locations. These groups include: 1)
coastal associations, including marshes and mangrove swamps,
lagoons and estuaries as well as depressions among dunes;
2) large, nearly flat, poorly-drained areas as exemplified by the
Everglades illustrated in figures 4, 5, 6, and 7; 3) river-valley
marshes such as the marsh adjacent to the St. Johns River; 4)
swamps of the flatland region (figure 8); 5) marshes bordering
lakes and ponds (figure 9); 6) seasonally flooded shallow
depressions; 7) lake bottom deposits (figure 10); 8) peat layers
buried beneath other strata (figure 11).
Cohen and Spackman (1977) have devised a more comprehensive
classification of south Florida's phytogenic (of plant origin)
sediments based on micropetrological studies. They first divide
BIG CYPRESS PROVINCE .. .
R RIDGE AND SLOUGH
Figure 4. Peat Provinces of Southern Florida. (Modified from Spackman et
SCAPE SABLE- -EE-8C
PEAT "10 3
MARINE MARL E
0 8 KM LIMESTONE E \
.SHELL BEACH I
-Mi. WATER 0
SW-NE cross-section from Cape Sable to vicinity of Tamiami Trail
and map showing line of section. (Modified from Spackman, et al.,
1964 and Spackman, et al., 1976)
Figure 6. Cross-section through a cypress hammock. (Modif*ed from Spackman
et al., 1964)
WATER FRESH WATER MARL
Cross-section through a "Bay Head". (Modified from Spackman et
---------- ------------- -- --------- ----1
- -- -e - - - -- --- - -
----- - - - --- -- -
---~------------- ---------- ------------ ------
-- -- -- -- -- -- -- ---- -- -
-------------------------- --- ------- ----
I----- -_-------------------------- -
--11--------------- ---- 11 ---------
-- 111--- ----- --------- ----- -
- -- - - ----- -
-- -- ----- ---------
ED PEAT, MUCK and SAND l SAND PEAT and MUCK D SAND, SILT and CLAY
Fige 8. Cross-section trough bay swamp and titi swamp. (Modified from
Cameron et al.,i 19771).
Figure 9. Peat deposits bordering lakes. (Taken from Davis, 1946)
HUNDREDS OF YARDS
FIBROUS SAWGRASS PEAT
Figure 10. Cross-section showing peat filling lake. (Taken from Davis, 1946)
SCALE VER [4FT.
LEGEND HOR. 200 FT.
SAND : 2
i MARL I- I- -
MA- MARINE I
PO PINE-OAK ::
Figure 1 cross-section using cores to show buried peat layer! (at eka
Dam Site, Oklawaa River, Marion County, Florida. ( fom
phytogenic sediments into two groups based on whether the plant
material is transported from the site of growth or deposited at
or near the growth sites of their source plants. Transported and
nontransported phytogenic sediments are subdivided as occurring
in marine to brackish water or fresh water. Specific environ-
ments are enumerated for both marine to brackish water deposits
and also fresh water deposits. Peats of these deposits are dif-
ferentiated based mainly on their botanical composition.
In Florida, peat deposits occur above or below the water-
table (Davis, 1946; Gurr, 1972). Wet peat deposits occur if the
watertable remains relatively high. Peat may be actively accumu-
lating in these deposits. Certain areas within the Everglades,
the coastal mangrove peats, and some lake-fringing peat deposits,
such as the one associated with Lake Istokpoga, are examples of
deposits which occur below the watertable. In other instances,
peat deposits are located above the watertable. This drainage
may have been instigated to enhance the land for agricultural
use. The Everglades agricultural region contains numerous tracts
drained'for this purpose. Other deposits have apparently been
drained as a result of regional lowering of the watertable. Most
peatlands in Florida occur at or below the watertable and, thus,
are very frequently also wetlands.
INVENTORY OF PEAT IN FLORIDA
MAPPING AND EVALUATING THE PEAT RESOURCE
There is no comprehensive inventory of Florida's peat de-
posits currently in print. Until recently, peat was not even
remotely considered as a fuel source in Florida; and several
scattered deposits were adequate to satisfy the state's agri-
cultural and horticultural needs. Thus, neither interest nor
funding were available for a complete peat inventory in the
It is important to point out that a comprehensive inventory of
Florida's peat resource is, of necessity, a massive undertaking.
The reasons for this difficulty are manifold. Florida is currently
estimated to have 6.8 billion tons of peat contained in 4,700
square miles (U.S. Soil Conservation Service). This peat occurs
in a variety of geologic settings which are both discontinuous
and widely distributed across the breadth and length of the
state. The various geologic settings of peat in Florida are
discussed in a previous section, "Geologic Settings of Peat
Accumulation in Florida."
These difficulties are compounded by the inaccessibility of
many peat-producing areas. Peat actively accumulates in wetland
situations typified by marshes, swamps, and mangrove islands.
Much of Florida's peat occurs in the Everglades region (figure
12). Due to extensive drainage in the Everglades the exact
II ~-9 I;
OF EVERGLADES !
Figure 12. Isopach maps of the Everglades region showing thickness of peat
and some muck areas. (Taken from Davis, 1946)
thickness and extent of the peat has decreased since figure 12
was prepared. Many of these areas are not accessible to
conventional vehicles. Their size and character may render foot
travel unfeasible. Some, but not all, sites may be accessible to
boats. Coring apparatus for taking samples and measuring
thickness must, in addition, accompany any field party charged
with assessing peat reserves.
A realistic appraisal of Florida's peat resource is further
complicated by the variability of the material. Peat may be
classified as fibric, hemic or sapric depending on the extent to
which it has decomposed (see section entitled "classification
systems applied to peat"). It also varies with respect to
chemical properties that affect its viability as a fuel source.
Complete assessment of the peat resource requires laboratory
analysis in addition to time-consuming field studies.
Attempts to assess the amount and locations of peat in
Florida are hampered by an additional factor. Peat deteriorates
by oxidizing when the wetlands where it accumulates are drained.
This drainage may be due to the activities of man or by natural
lowering of the water table in times of drought. Any data base
for peat will require periodic updating if it is to remain
CURRENT ESTIMATES OF PEAT IN FLORIDA
The total peat resources available in Florida are difficult
to estimate and published values vary widely. The paucity of
actual peat resource investigations is an important hindrance to
the development of accurate figures. A few published studies are
concerned with the entire state (Davis, 1946; Griffin, et al.,
1982). Several others concentrate on limited areas (Stephens and
Johnson, 1951; Gurr, 1972).
Individual county soil surveys vary in their usefulness due
to apparent inconsistencies in the terminology relating to
organic and organic-rich soils. The more recent studies were
used by Griffin, et al. (1982) to estimate fuel grade peat
resources. Unfortunately, these studies are not complete for
every county in the state. As a result, Griffin, et al. (1982)
were unable to provide a comprehensive inventory of the peat
resources for the entire state.
Another possible reason for the variation between resource
estimates may be the result of the specific material studied.
Griffin, et al. (1982) investigated "fuel-grade peats" while
Davis (1946) inventoried a variety of organic materials
classified as peats. The United States Soil Conservation Service
(1981) studies soils in general and describes their organic con-
tent in addition to other characteristics.
Griffin, et al. (1982) report the discrepancies among the
figures from various studies but were unable to determine the
reason for the differences. Griffin, et al. (1982) also state
that verbal reports from other Department of Energy peat
researchers indicate that they have found similar discrepancies
between the resource figures from the Soil Conservation Service
and their own figures in other states.
Published estimates of Florida's peat resources vary nearly
by an order of magnitude. Griffin, et al. (1982) provide the
lowest figure of 677',688 acres (1,059 square miles) consisting of
606 million tons of peat. Davis (1946) estimated 2,240,000 acres
(3,500 square miles), comprising 1,750,000,000 tons of peat. The
highest figure is provided by the Soil Conservation Service and
is 3,000,000 acres (4,700 square miles), or 6,900,000,000 tons of
The published resource estimates vary significantly and thus
should be used with reservation. The U.S. Bureau of Mines
currently uses the Soil Conservation Service figure (C. Davis,
personal communication, 1983).
The determination of a more accurate resource figure for
Florida peats would require a significant investment of time and
money to complete. The scattered nature of the deposits in north
and central Florida (figure 13) is such that there are literally
thousands of sites to be investigated. In south Florida, peat
deposits cover broad areas which would have to be examined in
order for accurate estimates to be prepared.
The greatest potential peat resources in Florida lie predo-
minantly in south Florida (figures 13, 14, and 15). The vast
majority of this peat lies in the Everglades and associated
swampy areas. It is interesting to note that while Davis (1946)
(figure 13) and the Department of the Interior (Christ et al.,
1981) (Figure 15) show similar areas of peat in south Florida,
I .- .
_", ,.. I
-. ,- EVERGLADS- -
MostlycSaw-9 ssPeo--,. l
A an I-'tt >.. : -', .Muck. and-T -. A at
8 Loxahatchee Peat
COASTAL MANR VE '-
E CORKSGLREW MARSH o -. .
Mostly Sowoross Peat -
A Muck and *oat -oq
B Loxahatche. Peat ^ --*---f'H 1
SALT-MARSH PEATS ^ ^ -
+ E CORKSCREW MARSH o + -, r---c- -
F VAN SWEARINGEN SLOUGH -. .
G ISTOKPOGA MARSH & SWAMP -- "
H UPPER ST JOHNS RIVER
FELLSMERE AREA -._ _
1 PEACE CREEK DRAINAGE --
DISTRICT AREA '
J CLERMONT MARSH -
K LAKE APOPKA MARSH Lt, .L '- -
L OKLAWAHA RIVER AREA
M ORANGE LAKE
N FLORAHOME AREA -_- ,."
0 SAMPLES TAKEN AND SMALLER '. -- ,. ... .
q PEAT AREAS' .
STATE OF FLORIDA 'IS<' .-.
C.L A'< ,- U D
S--- UI- ,- -. ,-.I -- --
7 x x 1 .0
,I^ ..L .
GtvLP oF MXxILo rC(\
Peat Deposits in Florida. (Taken from Davis, 1946)
* No Survey Avoilable
; I I 1
Z\ e/ f1
Figure 14. Fuel Grade Peat in Florida. (Taken from Griffin, et al., 1982)
Figure 15. Peat deposits in Florida. (Taken from Christ, et al., 1981)
Griffin et al. (1982) (figure 14) show a significantly smaller
area. This discrepancy may be due to subsidence and high ash
content which would render peat unsuitable for fuel use.
Griffin, et al. (1982) show peat deposits in Collier and Lee
counties that are not included on the other maps.
Figures 13, 14, and 15 indicate the presence of large depo-
sits in the St. Johns River Valley (Indian River, Brevard and
Ocange counties), and the Oklawaha River Valley (Marion and Lake
counties). Other relatively large deposits include: Lake Apopka
(Orange and Lake counties), near Lake Arbuckle (Highlands
County), Orange Lake area (Marion and Alachua counties) and the
Florahome deposit (Putnam County). Smaller deposits are also
indicated on Davis' (1946) map (figure 13) and Griffin, et al.
(1982) map (figure 14).
It is interesting to note that while Davis (1946) (figure
13) shows scattered samples taken from small peat areas in the
panhandle, Griffin, et al. (1982) (figure 14) show a number of
deposits including a large deposit in Leon County and smaller
deposits in Bay, Jackson, and Santa Rosa counties. The
Department of the Interior map (Christ et al., 1981) (figure
15) does not indicate any deposits in the panhandle.
Peat associated with mangrove and coastal swamps generally
occur in a narrow band paralleling Florida's coastline. The zone
occupied by these environments is widest in southwest Florida.
These peats are not generally shown on the maps of peat resources
due to the scale of the maps.
Until a more detailed investigation of our peat resources is
undertaken the published resource estimates must suffice. It
must, however, be kept in mind that the figures are estimates of
the available resources and vary from one investigator to
THE EVERGLADES AGRICULTURAL AREA
HISTORY OF THE EVERGLADES AGRICULTURAL AREA
The Everglades Agricultural Area is a part of an immense
natural drainage system that begins in the northernmost reaches
of the Kissimmee River drainage basin near Orlando. The
Kissimmee River flows to the southeast into Lake Okeechobee. In
its natural state, the level of Lake Okeechobee fluctuated within
a range of approximately 8 feet, that is, between 12 to 20 feet
above mean sea level (M.S.L.) (Parker, 1974). The water level in
the upper Everglades rose and fell in response to the
fluctuations of Lake Okeechobee.
In the wet season, most of the Everglades was inundated
much of the time. When the water level of Lake Okeechobee
reached about 14.6 feet (M.S.L.), two separate segments of the
lake shore would begin overflowing into the Everglades. At about
18 feet (M.S.L.), the entire southern shore (30 miles) overflowed
pouring a flood into the upper Everglades (Parker, 1974). It is
important to note, however, that losses to evapotranspiration are
estimated to have been as high as 82 percent. Thus, flood water
from Lake Okeechobee most probably did not travel the entire
length of the Everglades, but rather local precipitation caused
the inundation (Parker, 1974). This mass of water flowed
sluggishly to the Gulf and has come to be described as sheet flow
(Parker, 1974). The chronic inundation allowed the accumulation
and preservation of the organic soils which characterize the
highly productive Everglades Agricultural Area.
In about 1880, Hamilton Disston entered into a contract by
which he would drain land on the upper Kissimmee River and
receive as compensation half of the land he drained. His success
was debatable (Tebeau, 1974). The history of early drainage
efforts is a history of inadequate technical expertise and inse-
cure funding. The scope of the drainage issue was continually
underestimated. Disasterous floods associated with hurricanes in
1926 and 1928 moved the Federal Government to take action. The
extensive floods of 1947 and 1948 made it obvious that water
control had not yet been established and set the stage for the
intervention of the Army Corps of Engineeers (Tebeau, 1974).
In 1947, most of south Florida was flooded for several
months. The U.S. Congress, in response to the continuing water-
control problems, passed the Flood Control Act of June 30, 1948.
This action directed the Army Corps of Engineers to plan, design
and construct a massive project which would ultimately solve
water problems in all or parts of 18 counties in central and
south Florida (Snyder, et al., 1978). In the plan proposed by
the Army Corps of Engineers, major concern was devoted to the
protection of life and property along the lower east coast of
Florida. The first phase of the project involved building an
artificial levee from Lake Okeechobee to about Homestead in order
to confine flood waters to the Everglades. The project was also
designed to provide water control for soil, water conservation
and farming (Snyder, et al., 1978).
After studies by both the United States Department of
Agriculture and the University of Florida, the lands of the pre-
sent "Everglades Agricultural Area" were set aside for agri-
cultural development. The organic soils of the Agricultural Area
were the only soils of sufficient depth and of the proper type to
support cultivation for a period of time sufficient to justify
development (Snyder, et al., 1978). It is important to note that
when the Everglades Agricultural Area was being planned it was
recognized that subsidence of organic soil would occur and that
the area could not support cultivation indefinitely (Snyder,
CROPS AND SOILS OF THE EVERGLADES AGRICULTURAL AREA
The Florida Everglades comprises the single largest body of
organic soils in the world, 1,976,800 acres (Shih, 1980). The
Everglades Agricultural Area consists of 1,892,811 acres of fer-
tile organic soil. Winter vegetables from the Agricultural Area
include sweet-corn, celery, radishes, leaf crops, carrots and
beans. In addition, lands of the agricultural tract are used for
sugar cane, pasture and turf (Shih, 1980). Sugar cane is the
dominant crop with cash receipts of $215 million in 1977-1978
(Snyder, et al., 1978).
The proximity of the Florida Agricultural Area to the south
shore of Lake Okeechobee is not coincidence (figure 16). Before
the activities of man altered the tendency of Lake Okeechobee to
overflow along it southern edge silt, clay, and organic colloids
were mixed with dead plants to form muck. In this way, the mucks
became enriched in the microelements that peat lacks (Stephens,
1974), enchancing the mucks as an agricultural growth medium.
The soils of the Everglades Agricultural Area are classified
by soil scientists on the basis of the percentage of inorganic
matter they contain and their thickness. The Torry Series soils
occur within two to five miles of Lake Okeechobee. They contain
black organic layers more than 51 inches thick and are
characterized by a range of 35 percent to 70 percent mineral
matter (mostly the clay minerals sepiolite and montmorillonite)
(Snyder, 1978) and are not considered peats according to ASTM
standards. The Terra Ceia, Pahokee, Lauderhill and Dania soils
are dark organic soils which are differentiated from one another
based on their thickness above bedrock. The Terra Ceia soils are
the thickest with the Pahokee, Lauderhill and Dania becoming
successively thinner. As the process of subsidence occurs, Terra
Ceia soils will become Pahokee soils since Pahokee soils differ
from Terra Ceia soils only in their thickness (Snyder, 1978).
PRIVATELY BACKPUMPED LANDS
STATE OWNED LANDS
Figure 1 6.
Location map of the Everglades Agricultural Area. (Modified from
Snyder et al., 1978)
HI-- !! LLIII
Subsidence refers to the loss of thickness which is incurred
by organic soils when they are drained. A group of physical pro-
cesses are responsible for subsidence, including 1) shrinkage due
to dessication, 2) consolidation by loss of the buoyant force of
groundwater and loading, or both, 3) compaction by tillage, 4)
wind erosion, 5) burning and 6) biochemical oxidation (Stephens,
1974). The processes of drying, consolidation and compaction do
not result in actual loss of soil (Shih, 1980). Stephens and
Johnson (1951) documented an increase of oven dried weight for
Everglades peat from about 9 pounds to about 16 pounds per cubic
foot after cultivation. This increase in density corresponds to
a decrease in soil volume. In this manner, the volume of the
soil decreases although there is little actual loss of soil.
The processes of wind erosion, burning and oxidation do,
however, result in the actual loss of organic soils (Shih, 1980).
Wind erosion is thought to have minor effects in the Everglades
Agricultural Area. Numerous charcoal rich lenses which represent
ancient fires have been found at depth in cores through the
organic soils of the Everglades and coastal swamps (Cohen, 1974).
Attempts to correlate charcoal layers from core to core were
futile suggesting that fires were not widespread geographically.
The fires were confined mainly to sawgrass-dominated peats.
Modern observation indicated that fires are very common in
sawgrass communities and it is suggested that sawgrass may be
especially well-adapted to survival of fires (Cohen, 1974).
The most serious cause of long term subsidence in the
Everglades is biochemical oxidation. Biochemical oxidation has
been responsible for 55 to 75 percent of the total soil loss in
the upper Everglades Agricultural Area (Stephens, 1974).
Although original plans for drainage in the Everglades recognized
that subsidence would occur, the causes were apparently
misunderstood (Stephens and Johnson, 1951). Shrinkage of
original peat due to drainage was taken into account, but the
slow continual loss of peat due to biochemical oxidation was not
The organic soils of the Everglades are a collection of
organic particles and mineral particles which are interspersed
with void spaces or pores. When these pores are filled with
water the micro-organisms which actively decompose the organic
soil are unable to function or function at a greatly reduced rate
(Snyder, et al., 1978). This is the condition that allowed
organic soils to accumulate before modification of natural
drainage patterns. Biochemical oxidation of organic soils is
facilitated by warm temperatures, low water tables, high pH and
high organic content (Stephens, 1974).
Drained organic soils of the Florida Everglades Agricultural
Area subside at an average rate of approximately 1 inch/year
(Stephens, 1974). This rate varies with variation of depth to
the water table. Rates of subsidence for experimental plots with
water table depths of 12 inches, 24 inches and 36 inches were
measured to be 0.6 inches per year, 1.4 inches per year and 2.3
inches per year, respectively.
Subsidence has been documented in the Everglades using
repeated surveys of ground elevation along certain lines. In
figures 17, 18 and 19 (Stephens and Johnson, 1951), the solid
lines represent the original elevation of the surface of the
ground and the elevation as measured in 1940. The dashed lines
indicate the topographic elevations predicted from subsidence
rates. Stephens (1974) notes that subsidence was measured to be
33.5 inches between 1941 and 1966 in the upper Everglades which
may be compared to a predicted subsidence loss of 33.0 inches in
25 years (Stephens and Johnson, 1951).
Rates of subsidence in the Everglades Agricultural Area vary
with the depth to which the water table is maintained. The depth
at which the water table is maintained depends on optimum con-
ditions for each land use. Snyder and others (1978) note that
most vegetable crops produce high yield when the water table is
maintained at 24 inches below the surface. Sugar cane normally
requires a water table depth which is greater than 24 inches; and
in certain organic soils, a water table depth of 30 to 36 inches
greatly improves sugar cane quality. Water tables for cattle and
sod production may be maintained at levels which would be con-
sidered too high for most crops. It is important to note that
extremely high water tables may cause problems specifically
related to crop land use even though high water tables allow
maximum soil preservation (Snyder, et al., 1983).
Map of the Everglades Agricultural Area showing the locations of
profiles A-A' and B-B'. (Modified from Stephens and Johnson,
0 5 10 15 20 25 30 35
Profile A-A'across the upper Everglades showing the original
surface elevations and the ground elevation in 1940 as shown by
topographical survey. profiles for the years 1970 and 2000 are
estimated. (Modified from Stephens and Johnson, 1951).
5 10 15 20 25 30
Profile B-B' through the lower part of the Everglades Agricultural
Area show the original surface elevation and the surface elevation
as determined in 1940 by topographic surveys. Profiles for the
years 197 and n 2000 are estimated. (Modified from Stephens and
Johnson, 1951) 1 ,
Researchers who have worked in the Everglades Agricultural
Area suggest that maintenance of high water tables is the most
effective measure available for conservation of organic soils.
Tate (1980) notes that the only feasible means of controlling
subsidence is knowledgeable manipulation of the water table.
Snyder and others (1978) recommend: "For best conservation
organic soils should be kept flooded whenever not in use. When
soils are used, the water table should be maintained as high as
is possible for that use." Stephens (1974) lists a number of
suggestions geared toward conservation of organic soil: "(1)
provide adequate water control facilities for keeping water
tables as high as crop and field requirements will tolerate; (2)
make productive use of drained lands as soon as possible; and (3)
intensify research studies to develop practices to prolong the
life of the soils."
It has been suggested that extending the life of organic
soils by plowing under cover crops or litter (Snyder, et al.,
1978; Stephens, 1974) is probably not an effective conservation
measure. The rate at which peat forms is extremely slow and the
volume of plant litter produced is very small. Snyder and others
(1978) discuss an example which clarifies this relationship.
Sugar cane produces an amount of top growth exceeded by few, if
any, plants. An average cane crop (30 tons/acre) is estimated to
contain approximately 8 tons of dry matter. If all of the dry
matter from an entire crop were added to the soil, it could be
assumed that about half of it would be decomposed rapidly. One
acre-inch of top soil is about the amount lost to subsidence
each year in the Everglades Agricultural Area. That amount of
soil weighs approximately 50 tons. Thus, 4 tons are replaced each
year, which is still only approximately 1/12 the amount which is
THE NEAR FUTURE OF THE EVERGLADES AGRICULTURAL AREA
Snyder and others (1978) have included a discussion of land
use in the Everglades Agricultural Area through the year 2000.
It is noted that the predictions of Stephens (1951) have proved
reliable (compare figures 20 and 21). These predictions are pre-
sented in Table 2 (Snyder, et al., 1978). Although land eleva-
,tions are shown through the year 2000, subsidence will continue.
By the year 2000, only approximately 80,000 acres of soil three
feet in depth or deeper will remain. It is predicted that sugar
cane acreage will decrease, pasture acreage will increase signi-
ficantly and vegetable acreage will remain essentially unchanged
assuming the economic viability of such operations. By the year
2000, over 500,000 acres will be less than 3 feet in thickness.
Approximately half of this will be less than a foot in depth
(Snyder, et al., 1978). The depth of 3 feet is significant
because, at depths of less than 3 feet, the use of mole drains
becomes impractical. The soils which have subsided to depth of
PALM BEACH COUNTY
.M BEACH COUNTY
0 2 4 6 8 10 MILES
Figure 20. Soil depths predicted for the year 1980. (Modified from Stephens
and Johnson, 1951) Compare with Figure 17. (Taken from Griffin,
et al., 1982)
1 ,- .. .' MARTIN CO. 0
OEECH PLMEACH CO.
S- ... *
f. *:.:-:.': :. '. :*:** 10
PALM BEACH CO.
Figure 21, Thicknesses of soils from the Everglades Agricultural Area as
determined in r recent study. (Modified from Griffin et al.,
Proportions of the Organic soils of the Everglades Agricultural
Area falling into categories based on thickness (after Snyder,
YEAR 0 to 1 ft. 1 to 3 ft. 3 to 5 ft. over 5 ft.
1912 0 1 3 95
1925 1 3 7, 89
1940 1 7' 14 85
1950 2 7 28 76
1960 4 12 28 55
1970 11 16 41 45
1980 17' 28 41 14
1990 27' 28 39 7
2000 45 42 9 4
less than one foot face an uncertain fate. Snyder and others
(1978) suggest that while some of those soils may be suitable for
pasture, the soils may be abandoned for agricultural uses. It is
also suggested that the remaining soils and the existing water-
control structures be used to produce aquatic crops. The authors
suggest that such a usage could greatly extend the useful agri-
cultural life of the soils.
INDUSTRIAL USES OF PEAT
Industrial use of peat can be divided into two major
categories: extractive and non-extractive (Minnesota DNR, 1981).
The extractive uses include direct combustion, gasification,
industrial chemicals, horticultural products and sewage
treatment. The non-extractive uses include agriculture, energy
crops and again sewage treatment (Minnesota DNR, 1981).
PREPARATION OF PEAT FOR INDUSTRIAL UTILIZATION
For most applications, peat must be dewatered before pro-
cessing. Biogasification and some energy crops and sewage treat-
ment processes do not require dewatering.
Solar drying in the field is energy efficient but is not
suitable to wet mining processes or to all mining plans.-
Alternative dewatering processes include mechanical presses and
thermal dryers, in addition to pretreatment processes such as wet
carbonization, wet oxidation and solvent extraction.
Mechanical methods are limited in the amount of water they
can remove. Most of the water contained in peat is held in
chemical bonds, colloidal suspensions and small pores in the
organic matter. Mechanical methods may reduce water content to
70 percent at best (Minnesota DNR, 1981). Thermal dryers can be
utilized to reduce the moisture content further. The efficiency
of mechanical dewatering is greatly enhanced by pretreatment
processes such as wet carbonization, wet oxidation and solvent
extraction. Peat can be mechanically dewatered to approximately
30 percent water content after wet oxidation (Mensinger, et al.,
1980 in Minnesota DNR, 1981, p. 30).
Wet carbonization consists of heating a slurry of peat and
water (approximately 3 percent solids) to 300-400F.at 50-100
atmospheres of pressure for 30 minutes. A "peat coal" with a
heat value of 12,000-14,000 BTU/lb dry weight is obtained after
the liquid is removed (Kopstein, 1979).
Wet oxidation is an established process for the oxidation of
many wet organic materials. Air or oxygen is pressure fed to wet
peat in a closed, heated vessel. Combustion is rapid and is
controlled by the rate of supply of the oxygen or air. The pro-
cess can be stopped after enough heat has been generated to car-
bonize the remaining peat or can be carried to completion to
produce energy (Kopstein, 1979).
Solvent extraction reacts a heated peat-water slurry under
pressure with an organic solvent. The water is extracted from
the peat by the solvent. Subsequent to cooling, the absorbed
water is stripped from the solvent and after treatment is
disposed of as waste.
Direct combustion of peat is a method of producing energy
which has been utilized on a commercial scale in Ireland, Finland
and the Soviet Union for several decades. The Soviet Union had
installed an electric power station fueled entirely by peat as
early as 1914 (Kopstein, 1979).
The U. S. Department of Energy has developed several cri-
teria for fuel-grade peat. The criteria are: 1) heat value
greater than 8000 BTU/lb (dry weight), 2) greater than 80 acres
of peat per square mile, 3) peat depth greater than 4 feet, and
4) ash content less than 25 percent (Minnesota DNR, 1981). Hemic
and sapric peats are the most suitable for direct combustion
useage. The more decomposed peats (sapric) have been carbonized
to a greater extent but often have larger ash contents which
reduces their fuel value. Hemic peats generally are the most
suitable for fuel use (Minnesota DNR, 1981).
Direct combustion of peat is accomplished in boilers
designed or retrofitted for either peat fuel entirely or mixed
fuel feed. Boiler design must accommodate the characteristics of
peat fuel: low energy density, high moisture content. Both of
these characteristics result in increased cost (approximately 50
percent greater) of the boiler and feed system compared with a
coal or oil fired boiler of the same capacity (Kopstein, 1979).
Grate fired and fluidized-bed boilers require pelletized or bri-
quetted feed. Pulverized-fired boilers require peat ground to
the particle size compatible with the combuster design.
Direct combustion techniques can result in partial oxidation
of the peat and generation of synthetic fuel gases. Reduced oxy-
gen input and/or water vapor injection are required to generate
the fuel gases.
Peat is very reactive during gasification. Gasification can
yield low to medium BTU fuel gases, synthesis gases (those which
can be further upgraded by hydrocracking) fuel liquids, ammonia,
sulfur and oil byproducts (napthalene, benzene and phenol)
(Kopstein, 1979; Minnesota DNR, 1981).
Several basic designs of gasifiers are feasible for peat
gasification, however, data for peat gasification is primarily
limited to laboratory scale operations (Kopstein, 1979).
Entrained flow and fluid bed gasifiers appear attractive. An
example is the PEAT GAS process developed by the Institute of Gas
Technology. Dry peat is fed to the gasifier, and heated under
pressure with a hydrogen rich gas. The carbon in the peat reacts
with the hydrogen to form hydrocarbon gases (primarily methane
and ethene). The gases produced can be upgraded to pipeline
quality (Minnesota DNR, 1981). Byproduct oils (benzene,
napthalene and phenols), ammonia and sulfur are extracted in turn
from the liquids which are condensed during various gas upgrading
processes.(Minnesota DNR, 1981).
The ratio of gaseous to liquid products is controlled by
changes in temperature, pressure and length of reaction time.
Increased temperature and reaction time lead to gaseous product
increases. With higher temperature and longer reaction times,
the large hydrocarbon molecules comprising the liquid products
are hydrocracked into lighter gaseous molecules (Kopstein, 1979).
Biogasification is an anerobic fermentation process. An
important advantage of biogasification is that dewatering is not
required. -Biogasification is a two-stage process. In the first
step, the peat-water slurry is partially oxidized to break it down
to simple compounds. Aldehydes, ketones, organic acids and
esters are the main products at this stage. The pH is adjusted
and the mixture is transferred to the fermenter (anerobic biolo-
gical reactor) where bacteria catalyze methane production.
Methane and carbon dioxide are produced in stoichometric propor-
tions (Kopstein, 1979) with up 95 percent of the material being
converted to methane or carbon dioxide (Minnesota DNR, 1981).
The resulting gas can be upgraded to substitute natural gas (SNG)
by scrubbing the carbon dioxide and hydrogen sulfide from the
methane gas (Kopstein, 1979).
The waste material from the fermentation process contains
undigested peat components, inorganic residues and residual bac-
teria. These materials can be utilized for soil conditioners,
animal feeds, or can be concentrated for disposal. Excess water
is recycled to the fermenter (Kopstein, 1979).
Peat has been utilized as a raw material for the production
of industrial chemicals for many years in Europe and the Soviet
Union. U. S. interest has developed only recently. Peat bitu-
mens, carbohydrates and humic acids are extracted by processes at
low to moderate temperatures. Peat coke, peat tar and activated
charcoal are produced by pyrolysis. The use of peat for
industrial chemicals does not pose major technical problems. The
technology has been developed in Europe and the Soviet Union.
The chemicals produced are similar to petroleum derived products.
As petroleum becomes more expensive, the incentives to utilize
peat will increase (Minnesota DNR, 1981).
Peat bitumens are those peat components which are soluble
in nonpolar organic solvents. The yield of bitumens depends on
the extracting solvent chosen. Yield increases from low to high
in the following list of solvents: petroleum ether, gasoline,
dichloroethane, benzene, ethanol:benzene (1:1) (Fuchsman,1978).
Although various solvents are utilized for analytical purposes,
gasoline is the solvent used in commercial processes. Benzene is
not used because of health hazards (Bel'Kevich, 1977'). The peat
bitumens of commercial interest are peat waxes and resins. The
waxes are the most important commercially (Fuchsman, 1978).
Peat, suitable for commercial wax production, contains at
least 5 percent gasoline extractable material and has an ash con-
tent less than 10 percent (Lishtvan and Korol', 1975). The wax
content of peat is higher in more highly decomposed peats
(Naucke, 1966) particularly those with remains of shrubs and
trees (Fuchsman, 1978).
Dried peat particles in the size range of 0.02 inches 0.2
inches are required for efficient solvent extraction. Wax
extraction-utilizes gasoline as the solvent and extracts most of
the wax but relatively few of the resins (Bel'Kevich, 1977).
Gasoline and peat are mixed at 20:1. Approximately 5 percent of
the gasoline is lost in the process, with the rest being recycled
after wax removal by solvent evaporation.
The crude wax contains some resins. Resins are partially
removed by treatment with an appropriate solvent (cold acetone,
alcohol and ethyl acetate) (Fuchsman, 1976). Further purifica-
tion is accomplished by treatment with potassium dichromate and
sulfuric acid at 1670F-230F. The result is a fairly hard, light
tan wax (Bel'Kevich, 1977').
Peat waxes are produced commercially only in the Soviet
Union where they are used as release agents in foundary castings
and on polyethylene surfaces. Peat waxes are similar to montan
wax which is derived from lignite. Montan wax is a substitute
for beeswax and carnuba wax and is used as an industrial lubri-
cant and as an ingredient in shoe and furniture polish, electri-
cal insulating materials and in candles (Minnesota DNR, 1981).
Peat resins are the primary byproducts of peat wax produc-
tion. The resins are of importance as a source of steroids for
use by the pharmaceutical industry (Minnesota DNR, 1981).
Peat carbohydrates consist primarily of cellulose and
related materials such as hemicellulose and starches (Fuchsman,
1978). Sugars are produced by acid hydrolysis for use in yeast
culture. Yeast culture can be optimized for the production of
single cell protein or for the fermentation of alcohol (Fuchsman,
Peat suitable for carbohydrate hydrolysis, according to
Soviet criteria are: Spagnum peat with degree of decomposition
less than 20 percent, ash content less than 5 percent and at
least 24 percent of the dry weight of the peat recoverable as
fermentable sugars from the easily hydrolyzable carbohydrates (or
45 percent if difficultly hydrolyzable carbohydrates are
included) (Fuchsman, 1978). Cellulose is classified as being
difficult to hydrolyze. The preferred Soviet process (Ishino,
1976) is as follows: peat with a maximum grain size of 0.4
inches is.slurried with water to 7-20 percent solids and mixed.
The suspension is then pumped at 5-7 atmospheres of pressure and
concentrated sulfuric acid is added to give an overall acid con-
centration of 0.25-1 percent. The slurry is heated to
2840F-338*F by steam injection and discharged to atmospheric
pressure and reacted for 10-30 minutes. Volatile matter is
flashed off, the fluid is diluted and reacts for an additional 10
minutes at 2840F to allow hydrolysis completion. Solids are then
removed by sedimentation centrifuge or filtration. Yield by this
process is 34-40 percent of the peat dry weight.
Fuchsman (1978) describes humic acid as "alkali-soluble,
acid-insoluble organic compounds, excluding bitumens and
carbohydrates." There are several lines of chemical modification
of humic acid: pyrolysis, oxidation and reduction (Fuchsman,
To date, there are no large scale commercial uses for humic
acid. Present industrial uses for humic acids include sizing
for paper, tanning agents, in fertilizers and as viscosity modi-
fiers for oil well drilling mud (Fuchsman, 1978). Potential uses
include the production of plastics and synthetic fibers, com-
ponents for paints and adhesive formulations and flocculants or
thickeners in water purification systems. These uses are based
primarily on the adsorption and ion exchange properties of humic
acids (Fuchsman, 1978).
Peat Coke, Peat Tar and Activated Carbon
Peat coke, tar and activated carbon are produced by the pro-
cess of pyrolysis. Pyrolysis consists of decomposition of orga-
nic substances by heat in the absence of air. When carried to a
high enough temperature and for long enough time, the process
yields a carbon residue (peat coke), a water immiscible conden-
sate (peat tar) and non-condensable gases which can be utilized
as fuel gases.
Peat suitable for coking requires a relatively high carbon
content (high level of decomposition), low ash content and low
phosphorous content (Fuschman, 1978). High carbon content is
necessary for acceptable yields. Phosphorous and ash degrade the
Several factors influence the yield of pyrolysis products.
Coke yields are increased with more highly decomposed peats and
slower rates of heating. Peat tar and gases generated by the
pyrolysis process are often recycled as fuel for the coking pro-
Activated carbon is produced from peat coke by treating coke
with steam at 16320F-2012*F. The reaction forms hydrogen gas and
carbon monoxide which has the physical effect of expanding the
pores in the peat coke, greatly increasing the surface area
available for adsorption (Norit, N.V.).
Peat-coke is utilized to form high purity silicon for the
electronics industry and as a reducing agent in electric smelting
furnaces especially in the production of ferrochrome and ferrosi-
licon alloys (Eckman, 1975). Peat tars are refined for pesticide
and wood preservative use. The primary use, however, is as fuel
recycled to the peat coke production process. (Minnesota DNR).
Activated carbon is utilized for a variety of purposes, all
of which take advantage of the large surface area available for
adsorption. Uses include removal of pollutants from industrial
waste gases, as a gas absorber, deodorizer, and for purification
of water and sugar (Fuchsman, 1978).
USE OF PEAT AS A GROWTH MEDIUM
Essentially all of the peat mined in Florida, at the present
time, is used for horticultural purposes. Peat is used by home
owners'for soil enhancement, by nurseries and landscapers for
potting soils and growing media for plants, and also as a
medium for mushroom and earthworm culture.
Agricultural uses of peat are similar to horticultural uses.
The peat is utilized as a growing medium (soil) for agricultural
crops. The material is not mined, however, drainage is generally
necessary to provide the proper moisture conditions.
Hemic and sapric peats, as well as mucks, are utilized for
agricultural purposes. Fibric peats, typically are not suitable
due to the low pH (acidic) which makes nutrients unavailable to
many plants (Farnam and Levor, 1980). Large areas of Florida
peats and mucks are utilized for agricultural purposes.
Growing energy crops for plant biomass production allows
peatlands to be utilized to produce renewable energy sources.
Plant biomass can be harvested and burned directly or can be
gasified to produce liquid and gaseous fuels. Energy crops can
be an alternative to conventional mining (using the peat as a
growing medium) or can be utilized as a reclamation technique on
mined out peatlands (Minnesota DNR, 1981).
Plants which may be suitable for energy crop use in wetlands
include; cattails, reeds and sedges, willow and alder (Minnesota
DNR). These wetland species have two distinct advantages over
conventional crops for use in biomass energy production: 1) the
biomasss productivity of wetland species is often higher than
conventional crops (corn, soybeans, etc.) and 2) they can be
grown in wetlands unsuitable for conventional crop plants and
thus do not compete with conventional crop production (Minnesota
Peat has been utilized in the tertiary treatment of waste
water both in the U. S. and in Europe. The primary objective is
to reduce nutrient levels, primarily phosphorous and nitrogen
(Minnesota DNR, 1981).
Phosphorous is removed from solution by bacteria present in
that portion of the peat exposed to air. Bacterial metabolism
converts the phosphorous to insoluable forms. Chemical reactions
with calcium, aluminum and iron present in the peat also remove
phosphorous from solution (Nichols, 1980).
Nitrogen is metabolized by anerobic bacteria, converting
nitrate in the waste water to gaseous nitrogen which is released
to the atmo-sphere (Nichols, 1980). Additional nutrients are
removed through uptake by plants growing on the peat surface.
Three methods are commonly used for the tertiary treatments
of waste water. Two utilize the peat in place, the third utili-
zes excavated peat (Minnesota DNR 1981). The waste water can be
introduced directly to the bog surface and allowed to filter
through the peat or may be introduced to a ditched and drained
peat deposit. This would increase the volume of peat exposed to
the waste water, increasing residence time and allowing more
efficient nutrient uptake (Nichols, 1980). The third method
involves a built up filter bed of peat, sand and gravel. The
effluent is applied to the filter surface by sprinklers.
Generally, the surface of the filter would be seeded with a
suitable sedge or grass to remove additional nutrients (Minnesota
Peat water treatment systems and experimentation has not
been conducted for enough time to determine the period of time
over which it can effectively remove nutrients before it becomes
saturated. Environmental effects, therefore, must be strictly
monitored (Minnesota DNR, 1981).
Peat is currently mined in twelve Florida counties (figure
22). In each of these counties, the mining companies provide
jobs, pay state and local taxes, require the services of various
support industries and provide a valuable product to nurseries
PRICE, PRODUCTION, AND VALUE OF PEAT
The U. S. Bureau of Mines reports an average 1982 price for
Florida peat of $13.12 per short ton. 1983 prices quoted by
mining companies range from $8.50 to $18.00 per cubic yard of
9 o ,--
Figure 22. Location of Current Peat Producers. (Bureau of Geology survey for
peat with the most common price being $10.00 to $10.50 per cubic
yard. Blended topsoils range from $11.00 to $20.00 per cubic
yard. If one ton of peat is assumed to occupy 2.3 cubic yards,
the $10.50 per cubic yard price is equivalent to $24.15 per short
ton. Bagged peat prices are higher and are in the range of
$45.00 per ton.
Florida ranked second in peat production nationally in 1982
(Boyle and Hendry, in press, 1984). The U. S. Bureau of Mines
(B.O.M.) reported peat production in 1982 as 120,000 short tons,
with a value of $1,575,000 dollars (figure 23). The average
price in 1982 was $13.12 per short ton. The above figures repre-
sent a 25 percent drop in production and a 47' percent drop in
value from 1981.
The B.O.M. production and value figures do not represent the
complete picture. The B.O.M. reported peat production from four
counties in 1982. Of the ten companies on the B.O.M. peat
producer list, only six are still active. The authors have com-
piled a list of 21 peat producers, located in 12 counties. The
actual peat production in the state must be significantly higher
than reported by the B.O.M.
LOCATION OF PEAT PRODUCERS
Peat production is concentrated in central peninsular
Florida, in Sumter, Lake, Orange, Pasco, Hillsborough, Polk and
Highlands counties. Additional producers are located in Madison