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RESEARCH REPORTING SERIES
Research reports of the Office of Research and
Monitoring, Environmental Protection Agency, have
been grouped into five series. These five bread
categories were established to facilitate furtrer
development and application of environmental
technology. Elimination of traditional grouping
was consciously planned to foster technology
transfer and a maximum interface in related
fields. The five series are:
1. Environmental Health Effects Research
2. Environmental Protection Technology
3. Ecological Research
14. Environmental Monitoring
5. Socioeconomic Environmental Studies
»
This report has been assigned to the ENVIRONMFNTAL
PROTECT-ON TECHNOLOGY series. This scries
describes research performed to develop and
demonstrate instrumentation. equipment and
methodology to repair or prevent environmental
degradation ftom po-nt and non-point sources of
pollution. This tvork provides the ne ; or improved
technology required for the control and treatment
of pollution sources to meet environmental quality
standards.
-------
SELECTED WATER
RESOURCES ABSTRACTS
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-The application of chemical fertilizers to forest soils for
site amelioration is one of the newest and
most promising methods
for increasing production. Concern has risen over possible toxic
and eutrophic effects of fertilization on water quality. The
Environmental Protection Agency assembled
dati on the scope and
trends of the practice throughout the world
extent of actual or potential detrimental
in order ^o determine the
effects of forest
fertilization, and to evaluate priority for
grants .
Definitive
knowledge on the biological effects of forest fertilization is
incomplete or lacking in many aspects of tree physiology and soil
sciences, and in the long-term consequences
of forest fertilization
on toxic and/or eutrophic parameters of water quality."" Toxic levels
are usually not approached in natural water
applied nutrient loss is inconsequential.
supplies and the total
Results of completed forest
fertilization-water quality studies are summarized and evaluated,
and the status of current water quality studies is described.
Recommendations are given for reviews and
(Knapp-USGS)
new research efforts.
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WATEI RESOURCES SCIENTIFIC INFORMATION CFNTFR
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-------
EPA-R2-72-016
August 1972
FOREST FERTILIZATION
(A STATE-OF-THE-fRT REVIEW AND
DESCRIPTION OF ENVIRONMENTAL EFFECTS)
William A Groman
Pacific Northwest Water Laboratory
200 S U 35th Street
Con/all is, Oregon 97330
Program Element 1B2037
Ib
National Environmental Research Center
Office of Research and Monitoring
U.S. Environmental Protection Agency
Corvallis, Oregon
For sale by the Superintendent of Documents U 8 Government Printing Office Washington, D C 2M02 Price 65 cents
-------
EPA Review Notice
This report has been reviewed by the Environ-
mental Protection Agency and approved for
publication Approval does not signify that
the contents necessarily reflect the views
and policies of the Environmental Protection
Agency, nor does mention of trade names or
commercial products constitute endorsement
or recommendation for use
11
-------
i ABSTRACT
Information pertaining to the concepts, scope, and methods of
forest fertilization in various nations and regions of the world
has been compiled from available sources Factors influenc-
ing development to present status, possible trends, and impacts on
water quality are discussed
i
Results of completed forest fertilization-water quality studies
have been summarized and evaluated, and the status of current
water quality studies is described Recommendations for state
of the art reviews and essential research efforts are presented
-------
CONTENTS
Section Page
I Conclusions 1
II Recommendations 3
III Introduction 5
Purpose and Scope 6
Excluded Practices 6
IV Forest Fertilization 11
Development . 11
Current Status 15
Sweden 15
Finland 17
Norway . . . . 19
Denmark ... 20
France 20
West Germany . . . . 21
Great Britain 21
Other European Countries .... 22
New Zealand 22
Australia. ... .23
Japan . . 23
Canada . . 24
United States. ... . . . . 25
Pc-oific Northwest 29
Southern Pine Region 33
Influences and Possible Trends .... 37
Social 38
Economics 39
Technology 41
Application . . .... 41
Fertilizers 42
Soil and Tree Physiology Sciences 43
V Effects on Water Quality 45
VI References Cited 51
VII Appendix 57
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FIGURES
NO PAGE
1 MAJOR WESTERN UNITED STATES FOREST TYPES 26
2 BROAD PHYSIOGRAPHIC-EDAPHIC REGIONS OF THE SOUTHERN
UNITED STATES 27
3 ANNUAL ACREAGE FERTILIZED, PACIFIC NORTHWEST 31
VI
-------
TABLES
NO. frAGE
1 AREA FERTILIZED ANNUALLY IN SWEDEN 15"
2 AREA FERTILIZED ANNUALLY IN FINLAND 18
vn '
-------
SECTION I
CONCLUSIONS
1 The use of inorganic fertilizers is a forest cultural practice
that has accelerated rapidly in certain sections of the world within
the past ten years Although .relatively small in terms of fertilizer
production consumed and commercial forest area fertilized, the overall
trend has been toward increased acceptance and use of inorganic chemicals
to increase tree growtn
2. An interrelationship of socioeconomic corditions, technologic
advances, and scientific findings determine the rate and magnitude
of forest fertilization operations in any area at any point in time
3. Definitive knowledge on the biological effects of forest fertilization
is incomplete or lacking in man- aspects of tree physiology and soil
sciences, and in the long-term consequences of forest fertilization
on toxic and/or eutrophic parameters of water quality
4. The few forest fertilization-water quality studies conducted
to date indicate that toxic levels are not approached in natural water
supplies and that the total applied nutrient lost is inconsequential.
Numerous studies in progress or contemplated will provide more conclusive
information on the real or potential hoards, if any, of forest ferti-
lization on water quality
5. Increasing use of forest fertilization in certain areas, reappli-
cation to previously fertilized forest lands, changes in application
rates and fertilizer formulations, and new application methods could
conceivably cause toxic or eutrophic consequences if predictive results
and corrective procedures are not available
-------
SECTION II
RECOMMENDATIONS
This report has reviewed the state of the art of forest fertilization
and of water quality studies associated with the practice Although
a relatively new and minor operation, the use of inorganic fertilizers
to ameliorate forest soils has gained acceptance and expanded rapidly
over the past several years Consequently, the Concepts, methoos,
scope, and objectives of forest fertilization and of water quality
studies are constantly changing As a result, much of the conclusive
data essential for predicting tree growth and environmental qual-
ity parameters are incomp1ete or lacking
Two comprehensive and coordinated surveys are necessary to update and
maintain contact with various phases of forest fertilization-water
quality operations First, periodic compilation and summarization
of national and regional data pertaining to the state of the art of
forest ferti1ization should be conducted This information is vital
for determining tht scope, methods, and trends of forest fertilization
and for assessing conditions that have the potential to affect water
quality
Sf ond, a continual process of collecting and evaluating forest-
fertilizdtion-water quality studies is required to supplement and
refine current knowledge The few studies conducted to date indicate
no substantial or long-term detrimental effects on the environment
associated with the practice, however, the quantity and sophistication
of water quality studies contemplated or being conducted should provide
much needed definitive and predictive information
The following research areas should receive prime attention in the
immediate future.
-------
1 The most significant and practicable proportional reduction
of applied nutrient loss at this time can be accomplished through
avoiding direct application of inorganic fertilizers to surface waters
and riparian zones The minimum stream channel size to be avoided
and width of an effective riparian zone are currently speculative.
The numerous variables influencing conditions unique to each forest
stand must be investigated, analyzed, and correlated
2. As the practice of forest fertilization expands both in area
and in quantity of fertilizers utilized through reapplication to
previously fertilized lands, new environmental considerations ma>
appear
Monitoring of nutrient loss on forest lands has indicated that a
very small percentage of the total applied elements enter che drainage
system Nutrient concentrations have remained well below acceptable
levels, but the ultimate fate of accumulations of these nutrients
in streams, rivers, and impoundments has not been thoroughly investigated
The amount of introduced nutrients that an individual forested water
system can assimilate without deleterious consequences on the aquatic
ecosystem must be determined
3 Losses of applied fertilize 's through leaching and volatilization
are largely dependent upon rate, timing, and fertilizer formulation
Research efforts directed toward finding the most desirable interactions
of these components to minimize losses should be undertaken
-------
SECTION III
INTRODUCTION
Various socioeconomic factors have resulted in acceleration of intensive
cultural practices on forest lands for the purpose of increasing wood
fiber production Projected worldwide and national wood requirements
indicate dpficits within the next several decades, primarily due to the
needs of an expanding population and the lack of additional productive
forest lands to supplement existing sources (30) (40) (44)
The application of chemical fertilizers to forest soils for site
amelioration is one of the newest and most promising methods for increas-
ing unit growth increment (14) Although not a new concept, the main
body of forest soil fertility and tree nutrition research has occurred
since the late 1940's, the operational phase was initiated approximately
one decade *go as advancing fertilnzer technology, improved application
methods, and favorable economic conditions enhanced its feasibility
Research and practice of forest fertilization have progressed
exponentially, with practice generally empirical and preceding conclusive
or predictive research results
Within the past several years, concern has risen over possible toxic
and/or eutrophic effects on water quality from fertilization of agri-
cultural lands. Because of apparent similarities between agricultural
and forest fertilization, the latter is also liable for criticism under
a blanket indictment In addition, forest fertilization must undergo
scrutiny for possible detrimental alteration of soil, watershed, and
recreation values and as a potential disruptive agent in the forest
ecosystem.
-------
Realizing the concern of participants and observers on the effects of
forest fertilization on water quality, the Environmental Protection
Agency has assembled data on the scope and trends of the practice
throughout the world in order to determine the extent of actual or
potential detrimental effects of forest fertilization, and to evaluate
priority for related grants
Prior participation in forest fertilization-water quality studies
by the Environmental Protection Pgency has included monitoring of
two fertilized watersheds. One study was in cooperation with a forest
industry firm and the other with the U S Forest Service In
addition, grant support is pending for fiscal year 1972 with a forest
industry research organization to determine thf> extent of volatilization
and leaching of urea, and to investigate fertilizer formulations best
suited to minimize these losses
The brief period during which forest fertilization has been practiced, and
the relatively small magnitude of the operation in total annual tonnage
of fertilizers applied and forested acreage involved present a unique
opportunity to study forest fertilization-water quality relationships
as the program expands.
Research efforts in this area have been conducted and are intensify-
ing Therefore, as knowledge accumulates, situations which have potential
to degrade the environment may be observed and corrected before they
become widespread and irreversible
Purpose and Scope
The material presented in this report has been compiled through litera-
ture surveys, correspondence, and personal contacts The intent is to
provide a current and comprehensive description of various uspects of
forest fertilization and of related water quality studies throughout
the world. Restrictions on completeness are imposed by available
information and by rapidly changing knowledge and conditions.
-------
The first section of the report reviews the development and current
status of forest fertilization. The factors influencing possible
trends are also delineated and assessed The second portion summaries
the results of completed forest fertilization-water quality studies
and briefly describes the status of current or proposed research
efforts
Aerial application of nitrogenous fertilizers receives the main attention
throughout the report, inasmuch as this method currently dominates
operational forest fertilization The use of other application techniques,
essential elements (notably phosphates), and special purpose and
product objectives separate from increased wood fiber increment are discussed
where applicable
Excluded Practices
Operational forest fertilization has been defined as "that carried out
on commercial forests as part of a management plan with profit motive,
i e , as opposed to fertilization for ourely research purposes" (32).
This definition connotes application of chemical amendments to sizable
areas cf commercial forest lands in order to stimulate growth on new
plantations or established stands
However, fertilizer usage under the control of forest land managers
or occurring on forest lands for purposes other than operational
fertilization is practiced These operations will be excluded from
consideration and discussio Some are more closely related to agronomy
than to forestry, others are highly controlled and/or involve small
areas and application rates and, in certain instances, the growth
benefits derived through fertilization are sub-ordinate to other objectives.
Exclusion from consideration does not imply that none of these practices
has the potential for affecting water quality, but rather that they
do not fit the definition of operational forest fertilization . A
summary of specific purpose and special product uses of fertilizers
in forestry follows.
-------
1. Seed Production Areas. Specific purpose - to increase the produc-
tion of seed on selected trees within a forest stand Highly
controlled Small area.
2 Seed Orchards Specific purpose - to increase the production of
seed from genetically selected clones Similar to horticultural
practices. Highly controlled Small area
3 Christmas Tree Plantations. Special product - to improve color,
needle retention, and growth qualities Highly controlled
Relatively small area or portion generally involved
4 Forest Nurseries specific purpose - to improve germination, vigor,
and survival potential of seedlings Highly controlled Generally
small area or portion involved
5. Individual Tree Planting Specific purpose - to aid survival anJ
initial growth. Fertilizer applied to planting hole Highly
controlled Small amount of fertilizer pe>" land unit
6 Fire Retardant Specific purpose - applied aerially or by
taiker during fire suppression (loose control, variable area)
or aroun^ perimeters of controlled burns prior to ignition
(high control, small area).
7 Recreation and Aesthetics Specific purpose - to ameliorate heavy
use areas, encourage windbreaks and camping unit barriers, etc.
Highly controlled Generally small area
8 Wildlife Specific purpose - to encourage palatable and nutri-
tious browse for game species Control variable Area variable.
Policy decision by wildlife managers
9 Special Forest Understory Products Special product - to increase
quality of floral brush and greens. Generally a secondary benefit
of operational forest fertilization, otherwise high control and
small area
-------
10. Special Forest Products Special product - to increase quality
and/or quantity of high value commodities, such as naval stores,
mast, poles and piling, valuable harduoods, etc Generally highly
controlled. Area variable
11. Control of Water Yield Specific purpose - to regulate water yield
on all or portions of a watershed through control of vegetative
growth and subsequent evapotranspiration. Mainly theoretical and
experimental at this time
12. Range Management Specific purpose - to ameliorate rangeland and/or
increase quality and quantity of forage Different conditions from
the more closed system of a forest stand Control and area variable
Policy decision by range biologists
13 Cellulose Silage Specific purpose - to harvest coppica (sprout)
vegetation fron, fast growing species such as cottonwood and
sycamore for pulp mtn approximately five year rotations Rela-
tively new technique with promising potential Fertilization and
harvest methods similar to agriculture Acreage under intensive
cultivation currently small, possible rapid expansion depending
upon economic feasibility
14. Spray Irrigation Specific purpose - primary purposes are
alleviation of municipal and industrial treated waste disposal
problems and reclamation of spoil banks and harsh sites. Growth
response is a derived benefit. Highly planned and controlled
Amount of acreage and quantity of nutrients variable
-------
SECTION IV
FOREST FERTILIZATION
Numerous examples of dramatic and substantial growth response in
forest stands after application of inorganic fertilizers are pre-
sented in the literature In other instances, insignificant addi-
tional increment has been observed after treatment The differences
in magnitude of response reflect the rewness of the cultural practice
and the subsequent lack of detailed Knowledge necessary for predict-
ing and obtaining optimum growth objectives under a wide range of
physiographic, edaphic, climatic, and biotic variables
The state of the art of operational forest fertilization at any point
in time depends upon developments in and interaction of socioeconomic
conditions, fertilizer and application technology, and soil and tree
physiology sciences This interrelationship influences acceleration
or modification of the practice
Development
Tamm (43) separates the evolution of forest fertilization in Europe
into four periods F^om approximately 1865 to 1900 there was recogni-
tion of forest nutrient cycling ^nd of tree nutrient demands, but very
few experiments Investigations of a "trial and error" type, rarely
based on analytical thinking, occurred from about 1900 to 1925 The
next period witnessed the initiation of forest nutritional work on a firm
scientific foundation with numerous experiments The first limited
practical applications, particularly liming in Germany, were attempted
The start of large-scale forest fertilization began in 1960, and use
of fertilizers as a siIvicultural tool has increased dramatically.
A similar sequence of development has generally occurred in other areas
practicing or investigating forest fertilization, although regional
conditions have altered the dates, intervals, and research emphasis.
11
-------
Some of the reasons for the past neglect of interest in soil fertility
improvement as a scientific method for increasing wood fiber production
have been outlined by Gessel (13) Adapted for worldwide rather
than North American conditions these are
1. An adequate supply of accessible wood products to meet past
demands
2 A lack of interest in the management of non-agricultural
lands for production purposes
3. A lack of interest in the physiology of forest and range
plants, particularly with respect to mineral nutrition, and
the common belief that all forest soils contained adequate
amounts of essential elements
4. A general opinion among forest biologists that the natural
state is perfect, and that any nutritional changes imposed
on it by man would upset this balance and be harmful Even
though differences in land productivity and plant composi-
tion were recognized, very little research was initiated
5 The relatively low value of products from non-agricultural
land, commonly expressed in the phrase that "it is not
economical to put fertilizers on these lands"
6 The relatively restricted supply of fertilizers available
and their high cost of application
7 The general leek of information on the soils of non-agri-
cultural lands
8 The impression that added fertilizers would rapidly be leached
and lost from the site
12
-------
9. The common concept that the crops in question are strictly
soil builders, and therefore production does not consti-
tute a drain on the soil
10. Poor design and analysis of some of the forest fertilizer
work
Changes in concepts, knowledge, and conditions within the past quarter
century have reversed the insignificant attention previously paid to
forest soil fertility. The interaction of various factors has contri-
buted to the major role in increased forest productivity that amend-
ments are assuming
•
The dynamic advancement of forest fertilization to its present status
within the past 20 years and possible trends in the future are
inseparable components In order to avoid repetition anc' overlapping
emphasis the contributing factors will be summarized briefly in this
section for a simplified introduction to Current Status, and discussed
in detail unaer Influences and Possible Trends
Insufficient timber supplies to meet worldwide total wood requirements
within several decades have been predicted This problem has focused
attention on the necessity of employing intensive management practices
to exploit optimum growth and utilization
The situation is further compounded in certain regions by withdrf-wal
of anticipated timber reserves for recreational values, loss of higher
site commercial forest land to expanding population pressures, and
inaccessibility or low quality of existing timber supplies These
conditions have forced forest land man?gers to attempt to increase wood fiber
production on existing commercial forest lands and on converted or
reclaimed low quality sites
13
-------
The value of forest products has risen, and advances in fertilizer
technology, production trethods, manufacturing capacities (particu-
larly nitrogen fertilizers), and improved application techniques have
lowered total treatment costs per acre Investments in operational
forest fertilization not previously acceptable from an economic
standpoint when compounded over the periods of time involved are
now justifiable due to the value of the additional increment
realized through fertilization.
Intensified basic and applied research in forest soil and tree physiol-
ogy sciences has advanced knowledge in the fields of nutrient cycling
and deficiencies. Appropriate corrective measures necessary to achieve
increased growth objectives have been more adequately determined
Three general but major findings of forest soils studies are that (13)
1 The historical concept that forest vegetation is strictly
soil conserving is being placed in proper perspective
Under intensive management and harvest, non-agricultural
soils can be drained of essential plant nutrients just as
easily as soils under agricultural production The losses
may be more critical than in agriculture because forest
soils are frequently of a v~ry low nutrient status
2. Studies of the total nutrient cycle have demonstrated a
conservation of applied elements
3 Significant increases frequently occur in overall wood
production on forest lands when limiting nutrients are
applied Concepts regarding what is productive also are
changing as those designated as t'.ie best sites actually
show more response than poorer sites
14
-------
Generally, nitrogen has been found to be universally deficient in
forest soils, and nitrogenous fertilizers currently comprise the
bulk of inorganic chemical amendments used in forest fertilization
Phosphorus is required for and is used extensively on certain lands
Current Status
The following compilation of operational forest fertilization
practices in various countries and regions is inconsistent in
completeness and currentness due to the sources of information available.
Other nations not included may be practicing forest fertilization
on a small scale, although information on their methods and rates
was not available for this review
Sweden (15) (16) (17) (18) (19) (43)
Operational forest fertilization began in 1962 Mineral soils,
where mostly nitrogen (N) is applied, receive the main attention
of fertilization efforts, while peatlands, which require N, phosphorus
(P), and potassium (K) are presently relegated to a minor role in
the Swedish fertilization program (Table 1)
15
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Table 1
AREA FERTILIZED ANNUALLY IN SWEDEN
Year
1962
1963
1964
1965
1966
1967
1968
1969
1970
1971 I/
Mineral
Hectares
4017
5996
11500
40208
106131
100285
81026
77710
84187
115000
Soil
Acres
9926
14816
28417
99353
262249
247804
200660
192021
208026
284165
Peat! and
Hectares
749
1102
1021
765
906
665
978
2049
372
7
Acres
1851
2723
2522
1890
2238
1643
2417
5063
919
?
Total
626060
1547437
8607
21266
iy Estimated
The reduction in area fertilized beginning in 1967 was due to a
temporary economic crisis, but the 1971 data indicate resumption of
the prior trend.
The majority of fertilizer is aerially applied, mainly by fixed-
wing aircraft. Fertilization has been most common in stands 10 years
prior to harvest
Until 1968, urea comprised 95-100 percent of the nitrogen fertilizer
applied, but from 1968 to 1970 the share of urea decreased to
64 percent, while the use of various types of ammonium nitrate increased
in the same proportion The reason for tins shift in the type of N
applied may be based on a combination of economic and biologic considera-
tions
16
-------
The amount of N applied on a unit basis has steadily increased from
61 kg/ha (54 Ib/acre) in 1962 to 132 kg/ha (118 Ib/acre) in 1570
The application rate of N appears to be leveling at the latter figure
The total productive forest land in Sweden is estimated to be 21,500,000
hectares (53,126,000 acres) About 50 percent of the forest ownership,
and principally the best forest acreage, belongs to small landowners
and is difficult to organize for forest fertilization operations
Approximately three percent of the total forest acreage has neen
fertilized through 1971
On the basis of experimental data, it is estimated that the potential
area of forests on mineral soils to be fertilized amounts to 4,000,000
hectares (9,884,000 acres) The corresponding peatland area contains
2,500,000 hectares (6,177,500 acres) Thus, 15 65 percent of the
mineral soils and 0 34 percent of the peatlands amenable to fertilization
have been treated to date
The Swedisn Cellulose Company (SCA) has been the leader in forest
fertilization in Sweden. Their program calls for 15,000 metric
tons of N to be applied annually to approximately 60,000 hectares
(148,2CO acres) The same area is to be treated every five years,
meaning that roughly 300,000 nectar s (741,300 acres) of forest land
held by SCA will be continually provided with extra N
Other companies are expected to increase their level of participation
in the practice
Finland '34) (35) (43)
Finland has the most ambitious and comprehensive forest fertilization
program of all countries surveyed Coordinated high level, long
range planning, involving both government and forest industries,
anticipates increased forest growth of 12,300,000 m3 (434,313,000
ft ) per year
17
-------
More than 71 percent (21,740 hectares - 53,719,540 acres) of the total
land area is forested, 9,700,000 hectares (23,968,700 acres) of
the forested area are peatlands
Forest fertilization on a practical scale started in the early 1960s,
and the area treated annually has approximately doubled each year during
the first years for which data were available (Table 2) Contrary to Sweden
and Norway, the emphasis of the fertilization program has been on
organic peatlands since the beginning
Table 2
AREA FERTILIZED ANNUALLY IN FINLAND
Year
1961
1962
1963
1964
1965
1966
Hectares
20CO
4000
7000
12000
27000
50000
Acres
4942
9884
17297
29652
66717
123550
Total to 1966 102000 252042
Fertilization was scheduled for 80,000 to 100,000 hectares (197,680 to
247,100 acres) in 1967.
Revised plans in 1967 anticipated 330,000 hectares (815,430 acrei)
would be fertilized in 1970 increasing to 633,000 hectares (1,564,143
acres) in 1975, at which time the annual fertilized area was expected to
stabilize at that figure.
18
-------
A summary of the results of fertilization experiments in Finland indi-
cates that in mineral forest soils lack of N seems to most commonly
limit growth. Peatlands usually lack P and K, but are also often
deficient in N.
Through 1966, 0.46 percent of the total forest area had been ferti-
lized. In 1966, 33,000 hectares (81,543 acres) of the fertilized area
were peatlands and 17,000 hectares (42,007 acres) were mineral soils
Elemental ?! applied in urea and itPK fertilizers accounted for only
7.78 percent of the total fertilizers applied in 1966, the remainder
was in P, K, and PK fertilizers.
Norway (23) (43)
Based on the results of field trials, the fertilization program in
Norway is concentrated in older stands, where N has been found to be the
essential element contributing first and foremost to improved growth
Applications are repeated every s1/ to eight years In spruce forests
the best results are obtained with P in addition to N
Fertilization of younger forests is being investigated, but is still
in the research stage.
The first significant operational forest fertilization was conducted
in 1963, when about 550 tons of fertilizers were applied Rapid
expansion of the practice followed, and 2400 tons of fertilizers,
of which 2000 tons were urea, were placed on 7000 7500 hectares (17,297-
18,532 acres) in 1966. Ninety-five percent of the fertilized area
received N only.
The total forest area of Norway is 7,500,000 hectares (18,532,500
acres). Therefore, approximately 0.10 percent of the forest land
rfas fertilized in 1966 Authorities predict that the area fertilized
annually will be 10 to 20 t'nes higher in a few years
19
-------
Seventy percent of the application is by fixed-wing aircraft, heli-
copters are rarely used Small ownership units, averaging 20 to 30
hectares (49 to 74 acres) necessitate tractor and manual spreading
on much of the land
Twenty-seven percent of the productive forest lands are peat bogs.
Utilization of these lands is essential for increased wood fiber
production. Every year 10,000 hectares (24,710 acres) of peat bogs
are drained, and roughly 50 percent of these organic soils are in
need of fertilization In 1966, 1800-2000 hectares (4448-4942 acres)
of peat bog were fertilized with PK or NPK fertilizers The goal
for the future is significant increases in the fertilization of
amenable peat bog areas
Denmark (20)
Forest fertilization is still in the experimental stage in Denmark,
and an extremely cautious attit rde prevails toward the practice
Holstener Jorgensen (20) states that "some years will pass before
the first results of the experiments are available, and until then
we cannot start any actual consultative work in this field "
Experimental results indicate an overall N deficiency in the forect
soils Preliminary results reveal that P is deficient under certain
conditions The relationship between additional K and increased
growth is weak
France (25)
Because of severe fires which destroyed large areas of forest lands
in the past, France has been primarily concerned with reforestation
fertilization problems Work is just starting on established stand
fertilization
20
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Interest in forest fertilization of older stands is apparently increasing,
but information on the scope and methods of field operations is not presently
available
West Germany (14) (26) (43)
After a period of minimum attention to forest fertilization, interest
in the practice has been revived in West Germany The intensive
si1vicultural practices employed for different objectives under varying
conditions precludes a statistical breakdown of fertilizers and practices
employed
Generally, N has received much more attention than previously - even
anhydrous ammonia has been used successfully on certa.n terrain with
special equipment. Consequently, centers of nitrogen research in
forestry are developing
Available 1966 statistics for I'est Germany show 50,000 hectares
(123,550 acres) of the total productive forest land of 7,200,000
hectares (17,791,200 acres), or 0 69 percent, receiving fertilizer
treatment during that year One thousand metric tons of N were
consumed in 1966 by forest management practices, and the forecast
for future annual consumption (date unspecified) was 5000 metric tons
Great Britain (2)
Until recently, only phosphate fertilizers were normally used in British
forestry on a large scale. Their application was confined to older
stands on mineral soils where P is usually the most, if not the only,
limiting nutrient Younger stands planted on poorer soils, notably
acid peat, require only P to produce reasonable early growth, but sooner
or later K is generally required to keep the trees vigorous
21
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Nitrogenous fertilizers are beginning to receive more consideration in British
forestry - their short-lived effect previously made their use on
a field scale economically unattractive In future years, N and
K as well as P fertilizers may well be required on a large percentage
of the forest land in Scotland, and much of the forest land in Wales
and northern England may benefit significantly from P as well as
K
Advances in fertilizer technology and application methods are stimulating
the interest in and use of fertilizers for increased growth potential
in established forest stands Aerial application is becoming more
commonplace
Other European Countries (43)
/
The Netherlands probably have the most intensive use of fertilizers,
but their forest area is relatively small
East Germany and Czechoslovakia have some activity in forest fertilization
The practice in these two countries is evidently more intensive and
advanced than in the rest of eastern Europe, but information on the methods
and magnitude of operational fertilization in this area is not available
Ireland (29) has a cautious attitude toward extensive forest fertilization.
Current efforts are directed toward providing amendments for plantation
establishment on poorer sites P and K, in the form of natural mineral
fertilizers, are used
New Zealand (46).
In the mid-1950s, Mew Zealand started an active and continuing program of
applying approximately five-hundredweight (=254 kg = 560 Ib) of super-
phosphate per acre to between 30,000 and 40,000 acres (12,138 and 16,184
hectares) annually Application is primarily by aerial methods (any
stand more than five years old is fertilized by air), and 95 percent of
the treatment is applied to plantations
22
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Nitrogen has not been used in operational forest fertilization, although
research plots have been established However, grasses seeded on forest
lands for soil stability have had aerial applications of N.
Australia (12) (46)
Application 01 phosphates to plantations in Australia has been practiced
for some time with rates similar to those in New Zealand The terrain
permits ground application, although a small amount of aerial application
is practiced in West Australia Trace elements, particularly zinc,
sulfur, and boron are applied when specific deficiencies require correct-
ive measures
Research on N requirements is in progress, but to date only handspreading
of N fertilizers (mainly urea) around native Eucalypts has been
practiced
Japan (24) (36)
In Japanese forestry practices, forest fertilization is an economic
necessity. Species composition, quality, and ownership distribution
require combinations of intensive cultural methods for effective '
-------
forests and 101,000 acres (40,685 hectares) in private forests, for
a total of 143,000 acres (57,858 hectares), a 3 6-fold increase in
five years Most of the earlier fertilization was confined to young
plantations before crown closure, the fertilization of established
forests was begun on a large scale only several years ago
Both aerial and ground dissemination methods are utilized in Japanese
forestry The means of application selected depends upon both the
the type of fertilizer used and the silvicultural practices employed
Many of these cultural systems are costly and would not have been
feasible in other countries Within recent years, industrial progress
in Japan and accompanying wage increases for laborers have focused
attention on the need to develop new and less costly techniques for
forest fertilization.
The Forest Fertilization Society of Japan, supported by the national
and prefecture! governments, is the primary coordinating agency for
forest fertilization research
Canada (10) (11) (38) (41) (42)
Operational forest fertilization in Canada is not widely practiced,
althougn extensive and coordinated fertilizer trials are being con-
ducted on essential element deficiencies
In 1968, the Inter-Provincial Forest Fertilization Field Trials were
established in eastern Canada The Federal Government, five provinces,
three universities, and the Pulp and Paper Research Institute of
Canada are cooperating in standardized tests, this pooling of talents
and results is expected to yield more information rorc quickly than by
independent action Although timber resources in this region are
adequate for immediate needs, it is anticipated that the necessary
diagnostic, prescriptive, and applicative skills will be sufficiently
developed to permit the scientific use of fertilizers in forestry
when increased wood fiber production becomes a necessity.
24
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Information from a recent survey on the state of the art of operational
forest fertilization in eastern Canada showed two private companies
and one province engaged in the practice A total of 4,776 acres
(1932 hectares) had been treated through 1970 Aerial application is
utilized, and urea comprises the bulk of fertilizers applied The
province accounted for nearly 85 percent of the acreage fertilized
(1966 through 1970), and was tne only participant with a consistent
annual program
Operational forest fertilization was initiated in western British
Columbia in 1963. From available data, the total acreage operationally
fertilized through 1969 was 16,383 acres (6,630 hectares) Fixed-wing
aerial application using urea is preferred
Research activities in westurn Canada are coordinated by the British
Columbia Forest Fertilization Board, with supporting members from
private forest industry, the Canadian Department of Forestry, and
the British Columbia Forest Service As of July, 1959, 118 fielo
trials involving 1,705 plots had been established
United States (1) (4) (5) (6) (9) (14) (21) (?2) (27) (32) (38) (39)
Nearly all operational forest fertiI.zation presently practiced in the
United States is confined to two distinct areas - the Pacific North-
west (Douglas-fir Subregion) and the pine regions of the southern and
southeastern states (Figures 1 and 2) Although other forested sections
of the nation may possibly utilize operational forest fertilization to
some degree in the future (45), these two areas are widely recognized as
the potential primary wood fiber producing regions on a perpetual basis
due to past growth performances of indigenous species and other conditions
25
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Douglas-fir
I I Western hemlock-Sitka spruce
Redwood
Other Use
Figure 1 I1AJOR WESTERN UNITED STATES FOREST TYPES
(Adapted from American Forests 1971
Vol 77(10) Cover).
26
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n
Southeastern Uplands
Lower Mississippi Valley
Florida, Flatwoods, and Atlantic Coastal Plain
East Central Uplands
Other Use
Figure 2. BROAD PHYSIOGRAPHIC-EDAPHIC REGIONS OF THE SOUTHERN
UNITED STATES (Boundaries adapted from Stefferud
(37) as described by Bengtson (5)
27
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Recommendation 28 of the Public Land Law Review Commission, Dominant
Use Timber Production Umts (33), proposes the following public land
management policies.
There should be a statutory requirement that those
public lands that are highly productive for timber be
classified for commercial timber production as the
dominant use, consistent with the Commission's con-
cept of how multiple use should be applied in practice
The fact is that the purpose of the 1897 Organic Act
of the Forest Service, whose major aim was to assure
future timber supplies, has been obscured by changing
conditions and needs Yet the United States continues
to require timber and wood products in increasing
quantities The Commission believes that these and
other requirements can best be met by the identification
of highly productive areas of public forest lands
administered by the Forest Service and the Bureau of
Land Management, their classification for commercial
timber production as the dominant use, ana their
inclusion in separate timber management systems.
Lands classified for inclusion in this system would be
those that are rapable of efficient, high quality timber
production, and jre not uniquely valuable for other uses
Most of the forest lands to be included in such units are
in Alaska, California, Idaho, western Montana, Oregon,
Washington, and the southern states
Lands having a unique po+«->ntial for other uses should not
be included Critical watersheds, for example, where
cutting may be prohibited or sharply limited. Similarly,
important or potentially important intensive recreation use
sites close to urban areas should not be included On
the other hand, watershed, recreation, or other uses would
not be precluded on lands in the system
The best sites for timber grovnng are mostly at lower or
middle elevations in the West and in the southern states
In the West, outdoor recreation use tends to occur at the
higher elevations where the scenery is mo^e spectacular,
where there is snow for winter sports, and where the ground
cover is more open and suitable for hiking and other
summer sports The conflicts resulting from outdoor
recreation, on the better national forest timber production
areas in the South occur less frequently than in other
regions.
-------
The total area included in timber production units
would probably be less than one-half of the total
forest land now in Federal ownership, and less than
one-fourth of the total area of the national forests.
This is the land that will react most readily to
investments in timber management and will be the
key source of public timber for industrial uses
in the future
The recommendation applies to public forest lands, however, its
adoption would have significant impact on private ownership in these
regions due to location of processing facilities and research
emphasis
Regional information and analyses of timber production, potential
in the United States are provided by Barrett (3) and Clawson, Held,
and Stoddard (7)
Pacific Northwest.
The Douglas-fir Region of western Washington, western
Oregon, cod northwestern California is one of the most
important forest regions in the nation Almost three-
fourths (27 6 million acres) of the total area in the
region is ccmme-cial forest land Public agencies
administer about one-half (13 8 million acres) of the
commercial forest land, and the remainder is administered
by Forest Industry and other private ownerships For
all ownerships, over one-half the net sawtimber volume
in western Washington and Oregon is Douglas-fir
Throughout the region only 60 percent of all stands
are well stocked, 26 percent are medium stocked, 9
percent are poorly stocked, and 5 percent of the
area is nonstocked Information presented in the
"Douglas-fir Supply Study" published last year by
the Forest Service points out that over half of the
forested area is potentially more productive than
indicated by present net growth rates if subjected
to intensified management It is estimated further
that 10-1/2 million acres now support stands under
60 years of age At present it is not possible to
estimate what part of the total area may be expected
to yield an economic response, but the use of fertilizer
nitrogen to accelerate growth rates of both old and
young stands to full production represents a potential
application of thousands of tons of nitrogen fertilizer
per year to forested land in the Pacific Northwest (27)
29
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In addition to the Douglas-fir type, the commercial young redwood stands
of northern California and the western hemlock-Sitka spruce type along
the coasts of Oregon, Washington, and southern Alaska must be considered
as potentially amenable to fertilization (Figure 1).
Deficiency symptoms were observed and forest nutrition research was
initiated in the Douglas-fir Subregion in 1949 Laboratory studies
and field trials indicated and confirmed that nitrogen deficiency
is the most common limiting essential element to growth in this area.
Operational fertilization of forest stands was first practiced in 1965
when 1500 acres (607 hectares) were fertilized by Crown Zellerbach
Corporation in western Oregon Bulk urea was applied at a rate of
440 Ibs/acre (493 kg/hectare) by fixed-wing aircraft on an operational
trial basis.
Acreage and tonnage figures from 1966 through 1971, and especially for
the years 1970 and 1971, are not exact due to incomplete and extrapolated
fertilization data However, using a widely quoted base figure of 200,000
acres (80,920 hectares) fertilized through 1970, the total fertilized
acreage ti,rough 1971 is probably between 300,000 and 350,000 acres (121,380
and 141,610 hectares) If projections were reasonably accurate, the latter
figure should be more correct.
Figure 3 illustrates the rate of growth of operational forest fertiliza-
tion in the Pacific Northwest from 1965 through 1971
Only a small number (approximately six) of the public and private
organizations that could advantageously employ operational forest
fertilization on their lands have been actively engaged in the
practice since 1965. Three forest land management operations (Crown
Zellerbach Corporation, Weyerhaeuser Company, and the State of
Washington Department of Natural Resources) have accounted for more
than 99 percent of the total forest acreage fertilized in the Douglas-fir
Subregion thus far, according to available aata.
30
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o 100-
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65 6£> 67 68 69 7O 71
YEAR
Figure 3 ANNUAL ACREAGE FERTILIZED, PACIFIC NORTHWEST
Authorities anticipated annual fertilization of approximately 100,000
acres (40,460 hectares) in the first five years of the 1970 decade,
this figure has already been exceeded Annual fertilization is fore-
seen on 250,000 acres (101,150 hectares) during the last half of the
decade
31
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The original operational applications were performed by fixed-wing
airfcraft Helicopters were first used in 1967, and since that ^me
all recorded fertilization projects in the Douglas-fir Subregion
have utilized this dissemination method
Trials have been conducted with mechanical ground equipment, but terrain
and logistics have indicated little practical value for this method,
especially on larger acreages
Inasmuch as the soils of this region are commonly deficient in nitrogen,
urea pellets and prills have been used exclusively Application lates
are in the range of 330 Ib urea/acrp (370 kg urea/hectare) (150 Ib N/acre)
to 440 Ib urea/acre (493 kg urea/hectare (200 Ib N/acre)
The coordinating organization for fertilization research and information
dissemination is the Regional Forest Nutrition Research Project. This
body was officially formed in 1969 under the direction of the Inscituce
of Forest Products of the University of Washington, and is concerned
with Douglas-fir, westc -n hemlock, and Sitka spruce in Oregon and
Washington.
Cooperative sponsorship involves municipal, state and federal agencies,
forest industries, aerial application firms, and chemical companies
Twenty-nine organizations contribute funding and facilities. The first
field trials were established and initial measurements taken on 702
Douglas-fir and western hemlock plots in western Washington and western
Oregon during 1969-1971. The Project is now commencing thinmng-
^ertilization interaction trials, corollary examinations on the effects
of forest fertilization on various components of the ecosystem are also
being conducted
As a result of preliminary findings, the following general statements
appear to be applicable to growth response through fertilization in
the Douglas-fir Subregion.
32
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1. From all indications, nitrogen is the most effective element
for stimulating growth of Doug!as-fir and western hemlock
Other elements, alone and in combination with N or other
elements have not been adequately tested to evaluate their
potential importeince Other elements are like1,/ to become
growth-limiting when inadequate natural supplies of N have
been corrected by fertilizer application
2 Western redcedar and Sitka spruce have also shown response
to fertilization.
3. Cubic volume responses by Doug!as-fir to nitrogen range from
0 to more than 100 percent over the pretreatment growth rate
and probably average about 30 percent during a five to seven
year response period
4. Growth response has been obtained in Douglas-fir up to 300
years of age Most operational fertilization has taken place
on younger stands with closed crowns, the Regional Forest
Nutrition Research Project is concentrating its efforts on
field trial plots established in 1£- to 60-year old stands
5 Response to nitrogen fertilization has been noted over a
wide range of stocking densities and site qualities
Southern Pine Region The characteristics of the Southern Pine Region
present a more complex situation in respect to forest fertilization than
the Douglas-fir Subregion The primary differences are
1 Four distinct physiographic-edaphic subregions with varying
potential for increased wood fiber production
2 A more intensive cultural program and shorter rotations
3 Use of P as well as N fertilizers, ground as well as
aerial application, and fertilization of both young
and old stands
33
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There are approximately 200,000,000 acres (80,920,000 hectares) of
commercial forest land in the southern and southeastern states Roughly
one-half of this area is presently in hardwoods--the remainder is in
pine lands. Inasmuch as operational forest fertilization is not currently
practiced on the hardwood lands, discussion of the present status of forest
fertilization in the South will be primarily restricted to the intensively
managed pine lands.
Bengtson's (5) evaluation places the status and potential of the four
subregions (Figure 2) in perspective, and provides an understanding of
the current situation and probably development of forest fertilization
within each area to the year 2000 His summary is as follows
\
1 The outlook for profitable use of fertilizers in tne
East Central Uplands is not promising The forest base
upon which fertilizers would be applied doe^ not lend
itself to efficient fertilizer use The potential for
considerable forest growth increase is present on many
acres, but the quality and quantity of trees per unit
area are generally deficient for an economic response
Landowners in this area will probably choose to invest
available capital in regeneration and stand improvement
activities for some time to come
2. In the Lower Valley of the Mississippi and its similar
bottomlands, environmental conditions and native tree
species combine to provide a tremendous potential for
response to forest fertilization But the forests in
general are not in condition to fully realize this
potential. Forest fertilization will not contribute
greatly to production in this area until problems of
regeneration, stand composition/, and early stand
management are more completely worked out and the
results applied extensively Substantial effects of
forest fertilization on hardwood pulp production are
a distinct possibility, but important increases in the
supply of quality hardwood timber as a result of
fertilization cannot be expected in this century
34
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3. In the Southeastern Uplands, the outlook is more promising
Stands on many acres, par^cularly those of pine types, are
well-stocked, generally vigorous, and on soils at least
marginally deficient in nitrogen Judicious selection of
acres to fertilize can lead to increased total production
in this area of perhaps 5 percent, while yielding an
acceptance profit on the investment As more stands are
regenerated and holdings are consolidated, the potential
for increased production from both pines and hardwoods
through fertilization will increase
4. In Florida and the Flatwoods and the Middle Atlantic
Coastal Plan, I am virtually certain that a substantial
increase in production—perhaps 10 percent for the
region as a whole—will be made through forest
fertilization in the next three decades Most of this
increase will come from the less well-a«ained sites in
the area where excess moisture and nutrient deficiencies
have, in the past, strongly limited stand establisMent
and tree growth.'1
Because of these conditions, operational forest fertilization has been
mainly confined to the phosphorus deficient, poorly drained soils of
the pine Flatwoods of the Gulf and Atlantic Coastal plains
Two general ferti^zation principles have been prescribed for this
subregion. Early fertilization of between 80 and 100 pounds of
PpOr per acre (90 and 112 kg/hectare) is recommended on the phosphorus
deficient soils of the flatwoods Delaying the fertilization results
in very slow tree growth, and oft&n in poor survival. Since applied
phosphate remains available to the stand for long periods of time,
application should be at planting time or soon thereafter Small
amounts of nitrogen applied in combination with the phosphates usually
result in better growth than phosphates alone
35
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Older stands appear to respond favorably to nitrogen fertilizers (or to
nitrogen plus phosphate if the stand is in a phosphorus c ficient area)
Applications of 80 to 120 pounds of nitrogen per acre (90 to 134 kg/hectare)
have been used in established stands after crown closure Urea is the most
popular source of nitrogen
Serious research in the field of forest fertilization started about 25
years ago, and the first operational fertilization was conducted in 1963 on
630 acres (255 hectares). Through 1969, a total of 33,000 acres (13,350
hectares) had been fertilized. Host of the fertilization during this
period took place in 1968 and 1969
Available data through 1969 indicate that approximately one-half of the
fertilization was accomplished with ground equipment, and that 79 percent
of the fertilizers were applied to young stands
The proportion of various types of fertilizers applied were 82 percent
superphosphate only, 7 percent urea only, and the remainder were N-P
combinations
Fifty thousand acres (20,230 hectares) were fertilized in 1971 and,
assuming a moderate interim figure for 1970, approximately 110,000
acres (44,500 hectares) have received chemical amendments through
1971.
Thus, the total acreage fertilized through 1971 is roughly one-third
of the total area fertilized in the Pacific Northwest, a gross estiirate
of total fertilized acreage in the United States through 1971 would be
450,000 acres (182,070 hectares).
Two cooperative forest fertilization programs exist for the basic goal
of coordinated, efficient research into increased wood production Both
programs include participation by commercial forest owners, public
agencies, and fertilizer producers.
36
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The Cooperative Research in Forest Fertilization (CR1FF) effort was
initiated in 1968 under the supervision of the University of Florida
Its responsibility is investigation of fertilization in the pine region
in Florida and in the lower Coastal Plain of neighboring states
The other program was officially started in 1970 and is adminis-
tered by North Carolina State University Its concern is the southern
pine range from Virginia south and west into Mississippi exclusive of
the area covered by CRIFF
Influences and Possible Trends
The preceding survey indicates the wide range of emphasis placed upon
forest fertilization throughout the world due to varying concepts,
conditions, and objective's Bengtson's (5) assessment of the "prospects
and challenges ahead" for forest fertilization in the South are also
applicable in some degree to all fertilization programs His conclusions
are that
" . Beyond the year 2000, it is difficult to conceive of what
our forests will be like, what types of land they wi"1! occupy,
how extensive they will be, and what the demand price situation
for forest products will be Nevertheless, there is good reason
to believe that if we continue to upgrade the stocking and quality
of our existing forest, to employ, where appropriate, land manage-
ment techniques which complement fertilization, such as wetland
drainage, sub-soiling and liming, and more effectively control
competing vegetation, wildfire, insects and other pests
and pathogens, and press ahead with the selection and propagation
of tree genotypes having high fertilizer response potential, we
eventually will see fertilizer of some type beirg used profitably
on virtually every acre of commercial forest land in the South.
With these complementing factors of production brought into
effective coordination, we could easily double our present pine
growth rates per acre and perhaps treble current average rates
of growth of quality hardwood. Or we could, to put it another
37
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way, maintain present levels of production with half as many
acres of commercial forest land The achievement of tne effective
coordination of tree improvement, stand reoeneration, site amelior-
ation, and forest protection required to attain these goals is the
challenging task for silviculturists in the years imnediately ahead
It certainly ranks in importance with the research activities of
the specialists in these areas, because the greatest increases in
•.orest production will come, in most cases, not from any one of
these silvicultural activities but from their multiplying effects
one upon the other "
The newness of the practice and the resulting dynamic changes occurring
preclude accurate predictions on the magnitude and trends of operational
forest fertilization in the future Rather, the interacting influences
of social, economic, technologic, and contemporary scientific knowledge
will determine future policies That forest fertilization will
increase and become more refined and predictive is evidenced by the
progress made in the past few years, the rate and magnitude of acceptance
and growth of the practice will depend upon the interaction of the
following variables with each other at any point in time.
Social
According to Osara (30), a number of countries have problems of over-
popuTation and/or climatic factors that have led to such pressures on
good land that little or nothing can be set aside for the production
of wood.
Some marginal lands may be available for this purpose, but the question
arises whether it will be possible to develop international trade
to such an extent as to enable these countries to cover their requirements
by imports from wood surplus areas Perhaps one day fertilizers
will play a role in expanding indigenous production of wood, despite
adverse conditions and high costs, at the present time, however,
it would hardly be opportune to speak of a major use of fertilizers
for trees in countries where the population suffers from hunger or
malnutrition
38
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Therefore, it may reasonably be assumed that forest fertilization
in the future will generally be confined to developed nations with a past
history of substantial wood fiber production and that are currently
practicing intensive and progressive forest management practices. In
effect, these conditions restrict operational forest fertilization in
the foreseeable future to those countries listed in the preceding survey
that are employing or considering fertilization as a silvicultural tool
Other nations and regions not listed, such as the USSR and sections
of the U.S. and Canada could conceivably initiate fertilization practices
if economic, technologic, and scientific factors become favorably balanced
Pressures in the developed wood fiber producing countries due to expand-
ing populations very likely will force further withdrawal of some of the
higher site lands for population expansion and existing mature timbered
areas for recreation and other values, in turn shifting some forest
land man. gement operations to p eviously neglected, poorer site lands
Economics
The basic inducement to fertilize depends upon the realization of
a substantial increase in wood fiber increment Objectives vary
as a result of the combination of existing forest conditions and
economic situations unique to each land manager practicing forest
fertilization
The economic reasons for employing operational forest fertilization for
increased growth are varied, several economic factors may be considered
and applied in order to attain specific goals.
The most bas c principle is production of a greater volume of wood
fiber from a treated stand than would be realized over the same period
of time and on the same area of unfertilized land Thus, if X units
of wood fiber per acre would normally be anticipated from an unfertilized
stand, and if X + F units were produced through fertilization alone
or in combination with other cultural treatments, the added incre-
ment provided by F would justify the treatment investment,
39
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provided the value of F were equal to or exceeded the fertilizer
investment compounded annually at an acceptable rate of return
Perhaps a more realistic way to consider the economics of fertilization
caused by a shrinking forest land base is through a shortening of
the rotation period. This example of resource substitution would
produce the same volume (due to increased increment through fertilization)
on the same area but in less tirce — equivalent to growing the same
volume on less land.
This concept in effect increases the amount of land under management
without additional acquisition, and eliminates the purchase price of
land and additional fixed costs such as taxes, road construction and
maintenance, protection, and cultural practices The price of land and
fixed costs per acre have been rising, while the exoense of fertilization
has dropped within the past decade and remained relatively stable over the
past several years
Another option to be considered by forest land managers is the stimulation
of growth in immature stands on better sites close to established mills,
thereby decreasing transportation costs and, in some instances, increasing
wood quality
Correcting existing unbalanced age class distributions for sustained yield
is another potential benefit that may be possible through fertilization
Preliminary investigations indicate that under certain conditions the
growth effects produced by forest fertilization interactions with other
cultural practices are synergistic and not additive Silvicultural
methods such as thinning, drainage, irrigation, and tree 'improvement,
employed in conjunction with fertilization, may make the combined
practices economically attractive, whereas if conducted singly their contri-
bution to increased increment would be inadequate
In dense young precommercial stands, fertilization has accentuated
expression of crown class dominance, thus enhancing its feasibility
as a less cos.tly method of precommercial thinning than the currently
40
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used mechanical methods A bonus is the addition of necessary soil
amendments
Certain countries must maintain a favorable export-import balance
through forest products in order to support the development of other
industries. An associated aspect in areas with a past history of
wood fiber production and declining resources is "national p"ide "
Technology
Application. On operational forest fertilization projects, hand
spreading, ground machine, or aerial application methods are employed.
Hand spreading is feasible only in areas where labor costs are low
and accessibility, size, and terrain of the project site are not
prohibitive factors This technique offers few advantages except
in specific unique situations, and is not nor will it become a
dominant factor in operational forest fertilization. Ground machine
applications are presently the cheapest methods and are particularly
adaptable for treating young plantations on level ground They are
only effective when soil conditions, vegetation, tree size and distribution^
or topography do not limit operations.
Control of fertilizer distribution by ground equipment is highly
regulated. No substantial cost reductions can be anticipated through
development of new equipment.
Aerial application is most commonly used because it enables treatment
despite highly variable ground conditions
Fixed-wing aircraft are preferred for certain situations, but this
method has the liability of requiring a suitable runway close to
the fertilization operations Helicopters, on the other hand, have
greater maneuverability and less stringent landing site requirements.
41
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Increased load capacity and improvements in design of dissemination
systems developed over the past few years have further advanced the
helicopter to the forefront of application methods.
Helicopters with pod capacities up to 4000 pounds (1814 kilograms)
are currently utilized Tins size is capable of applying 25 tons of
fertilizer per hour. The logistic problems of supplying fertilizer
in bags or bulk containers to the landing site in quantities necessary
for continuous operation and the larger transport systems and landing,
storage, and loading areas required preclude an indefinite increase
in helicopter size The amount of acreage involved in the individual
fertilization project also favors smaller aircraft in certain situations
Bergland (6) believes that improved equipment designs are possible
through several avenues These are reduced costs of coordination,
handling, and application, simplified adjustments for rate and swath
width, and greater accuracy, uniformity, and versatility throughout
the dissemination process Ircomplete operational cost data and
technical difficulties of equipment evaluation cloud the tangible dollar
benefits of new equipment designs Environmental constraints, caused
by the need to exclude streams and lakes from treatment areas dictate
that equipment development should provide acc'rcte placement of fertilizer
more economically rather than provide economy by sacrificing accuracy.
Fertilizers The impetus for development of new fertilizer formulations
or changes in the use of existing chemical amendments for specific
conditions will depend upon the findings of continuing research efforts
of soil and tree pnysiology sciences
Many of the operational forest fertilization projects undertaken have
been conducted without definitive knowledge of the correct timing,
rate, and fertilizer formulation required for optimum growth response
of the species based on site, age, and stocking. As a consequence,
applied nitrogen has been lost through volatilization, leaching, and
luxury consumption
42
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The cooperative forest nutrition research programs and other pertinent
investigations are designed to provide this essentia1 information
Fertilization programs may then be objectively planned for maximum
growth benefits with least expenditure and environmental degradation
Commercial fertilizer manufacturers anticipate no major production
breakthroughs in the immediate future which will increase the proportion
of nutrient(s) per unit of weight or reduce the bulk price of fertilizers
significantly below their present costs Formulations, additives,
and prill coatings are presently undergoing testing for nitrogenous
fertilizers to reduce volatilization loss or to inhibit nitrification
and subsequent leaching.
One technique which could possibly become operational is the use of liquid
or fluid fertilizers instead of pellets and prills in aerial application.
This method would further diminish control during dissemination and subject
initial distribution to the atmospheric loss and drift experienced by
aerially applied pesticides (28)
Soil and Tree Physiology Sciences
The nurjer of variables to be investigated and the length of time required
for conclusive results to be obtained control the rate and magnitude
at which forest fertilization will be accepted and practiced, especially
where only marginal economic returns are anticipated A number of
indicative findings have been accomplished, many more interdisciplinary
efforts are being conducted or contemplated
Results of studies in these sciences will ultimately determine the
economic feasibility of fertilization, delineate the areas included
or excluded from the practice, and specify the fertilizer formulations,
rates, and time of application necessary to optimize tree growth and
minimise nutrient loss.
43
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SECTION V
EFFECTS ON WATER QUALITY
Concern has been expressed by both participants and observers over
possible detrimental effects to the environment caused by the use of
inorganic fertilizers on forest lands No deleterious consequences
have been discovered so far, but interested organizations, especially
in the United States, are accelerating water quality research efforts
in order to understand the effects of forest fertilization on the
ecosystem, to dispel incorrect assumptions with concrete information,
to recognize and correct harmful aspects before they become irreversible
and, ultimately, to insure that forest fertilization will not be placed
under restrictions that will diminish its value as a silvicultural tool
Former concepts that 1) all forest soils contained adequate amou.its
of essential elements, 2} any nutritional changes imposed on the
natural state by man would upset the balance and be harmful, 3)
ferti^zers would rapidly be leached and lost from the site, and
4) forest crops are strictly soil builders and production does not
constitute a drain on the soil (13) have been revised throjgh findings
of research efforts conducted within the past several decades
Forest soils have generally been found to be deficient in certain
essential elements, especially nitrogen In some instances, adequate
reserves of essential elements are present, but in forms unsuitable
or unavailable for plant growth Even the higher sites which were
previously considered to be sustaining maximum growtli have shown
dramatic increases in increment when fertilizers have been applied
In contrast to cultivated lands, the forest soil generally has a
highly organic layer over its surface and otgamc matter content
of the top few inches is almost always greater than that in cultivated
soils. This substantial amount of organic matter provides a large
number of adsorption sites for applied chemicals Further, most
well-established forest stands, including understory vegetation,
Preceding page blank 45
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have a massive root system that offers great opportunity for interception
and rapid uptake of chemical fertilizer nutrients (27).
Undisturbed forest soils, in contrast to agricultural soils, are
credited with restricting losses of essential elements through leach-
ing since elements are retained within a cycle between the plant
and soil systems, and a general deficiency of amons exists in a
forest soil profile of the temperate region (8).
The two primary methods by which applied nutrients may enter stream
channels are by direct application to the water surface or through
subsurface flow Overland flow of water on well-vegetated land is
inconsequential as a means of transporting applied fertilizers into
water courses, except for occurrence on roads, trails, and other
compacted areas with exposed mineral soil.
A numbet of lysimeter studies and several watershed monitoring investi-
gations have been conducted on fertilized areas. Most of the research
emphasis has been directed toward determination of conversion, cycling,
and loss of the mobile forms of nitrogen
The lysimeter work has shown rather conclusively tnat leaching of
nitrates (the toxic form of nitrogen) into the ground water is
insignificant Forest soils are excellent filters for most plant
nutrients because of their high exchange capacities and the den«;e
root systems which can absorb and recycle nutrients (28).
The few watershed monitoring studies completed to date were accomplished
by sampling and analyzing stream flow from fertilized watersheds or
portions of drainages. In all investigations, application was by
helicopter, except for one trial application of ammonium sulfate, urea
was used exclusively A listing of the completed and analyzed studies
is presented in the Appendix
Although the degree of sophistication in experimental design, timing
and rate of application, and components analyzed differed among
studies, similarities in the behavior of critical parameters were observed.
46
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A summary of the major findings indicates the following general
characteristics
1. Urea-N and Kjeldahl-EJ reached short-lived peak concentrations
shortly after fertilizer application, and returned to pretreatment
levels within several weeks Strong evidence is presented that the
initial increase of urea-N concentrations was primarily due to direct
application to surface waters, this contention is substantiated by low
initial concentrations where surface waters were intentionally avoided
during application
2 A small increase in ammoma-N above pretreatment levels was
observed shortly after application Concentrations quickly returned to
pretreatment levels, the magnitude and duration of ammoma-N loss
appeared to be associated with surface water application and hith
volatilization loss dependent upon climatic conditions immediately
after application
3. Loss in th- form of mtrite-N was minimal and insignificant,
apparently due to rapid conversion of nitrite-N to mtrate-N through
nitrification
4 Nitrate-N contributed to the greatest and most persistent loss
of nitrogen on all study area:. The initial significant loss occurred
within a period of several days after application, subsequent substantial
losses were associated with the intensity and duration of precipitation
Virtually all of the nitrogen losses after the initial peaks associated
with application were in the form of mtrate-N
5 Short-lived and inconsequential ammomum-N losses immediately
preceded the mtrate-N losses, and coincided with the initial onset of
precipitation
6 Data from one study suggest the possibility of significant
interactions involving urea fertilization and disc i^rge of cations from
the watershed. A definite increase in the conce tr^tions of calcium,
magnesium, sodium, and potassium in the stream following fertilization
was observed
47
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7. In none of the studies was the Public Health Service maximum
permissible level of nitrogen in public water supplies seriously
approached as a result of fertilization
8 Losses of applied nitrogen to stream channels ranged from
inconsequential to a maximum of three percent Data vary according to
stream surface area, rate and consistency of application, and other
factors unique to each study, but approximately one-third to one-half
of the total nitrogen loss may bt associated with direct application
to the surface water and immediate riparian zone
A study on the possible transport of urea-N conducted in Sweden showed
a slight increase in the nitrogen content (mainly ammomum-N) in stream
and lake water. After fertilization in 1969, it was calculated that
30 to 40 kg (66 to 88 Ib) of nitrogen out of a total of 11,000 kg
(24,250 Ib) of nitrogen was deposited in the recipient. In 1970, the
corresponding figures v?re 10 to 20 kg (22 to 44 Ib). The maximum
percentage lost over the two years would not exceed 0 5 percent of the
total nitrogen applied (18)
Early in 1971, a number of areas in Sweden scheduled for fertilization
later in the year were selected, and one or more natural springs, includ-
ing controls, were used for wdter sampling at definite intervals before
and after fertilization Preliminary data show that an appreciable
increase in ground water mtrog^ i resulted only after ammonium nitrate
application, this condition occurred in only a few cases Howevet, in
one of the springs and on one occasion the nitrogen concentration reached
a value of 8-9 ppm of mtrate-N. Urea produced no noticeable increase
in the water nitrogen concentration. This study is continuing (18).
The replication of phosphorus on organic soils has received the greatest
research attention in Sweden Two projects have been initiated, results
to date indicate that on one peat type no P fixation occurs when the
fertilizer is applied in a water soluble form (superphosphate), while
the nonsoluble forms used (basic slag, apatite) do not seem to be leached
out 08).
48
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An extensive sur/ey of public and private organizations concerned
with the practice of forest fertilization and its effects on water
quality revealed a large number of well-planned lysimetry and barometer
watershed studies in various stages of preparation and sampling
Government agencies, universities, and private industry are involved
individually or cooperatively The studies are not wholly confined
to the regions presently practicing operational forest fertilization,
and the behavior of other essential elements in addition to nitrogen
are being investigated The numbers, types, and sophistication of
current research efforts, in addition to the restrictions imposed by
the lack of a coordinating agency, precludes a listing and summary
of these research projects and objectives
The scope and intensity of these studies will eventually form the
basis for trore predictive parameters than the few previously conducted
The projects range from simple monitoring of fertilized watersheds
to assessment of the impacts of introduced nutrients on the whole
forest ecosystem The water quality studies must naturally be evaluated
in their relationship to the findings of tree growth, economics,
environmental impacts, and other criteria
As well as specifying the type, quantity, and pathways of applied nutrient
loss under a wide range of conditions, the conclusions will aid in minimiz-
ing and controlling losses through delineation of the
1 Most suitable rate of application
2 Most satisfactory type of fertilizer formulation
3. Proper seasonal and chronological timing of application and
reapplication.
4. Areas with potential for substantial nutrient accumulation
in impoundments
49
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The National Environmental Protection Bo*rd of Sweden and the Roya"
College of Forestry have a small budget allocated for water quality
studies In addition to those previously mentioned, the largest
project encompassing investigation of all components of a fertilized
forest ecosystem is underway It is not anticipated that many more
water quality studies will be initiated in Sweden until a substantial increase
in forest fertilization can be foreseen (18).
Investigations are being carried out in Finland on the washing away of
nutrients on peatlands as well as the total nutrient balance No
results have been published to date (31)
In New Zealand, catchments have been established for research on
phosphate levels, but otherwise there has been very little investigation
1n this area (46).
50
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SECTION VI
REFERENCES CITED
1. Anderson, Harry W. 1969 Douglas-fir region aerial fertilization
makes strides in a brief span of years Forest Industries
96(11)-30-32.
2. Atterson, J and E J. M. Davies 1967. Fertilizers--their use
and methods of application in British forestry Scottish
Forestry 21(4) 222-228
3. Barrett, John W 1962 Regional silviculture of the United States
Ronald Press, New York. 610 p.
4. Bengtson, George W. 1969 Routine fertilization of vast acreages
in the South may be ultimately practiced. Forest Industries
96(11) 35-37
5 1970. Potential increases in wood production
through fertilization of forest land in the South. In
Nutritional Problems and Practices on Forest Land A Symposium
sponsored by the College of Forest Resources, University of
Washington, Seattle Mimeo, unnumbered leaves
6 Bergland, Robert T. 1971 Practices and problems in forest
fertilization. Paper No 71-176 presented at the 1971 annual
meeting of the American Society of Agricultural Engineers.
Washington State University, Pullman. 17 p
7. Clawson, Marion, R. B. Held, and C H Stoddard 1960 Land for
the future. The Johns Hopkins Press, Baltimore 570 p.
51
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8. Cole, Dale W. and S. P Gessel 1965. Movements of elements
through a forest soil as influenced by t»-ee removal and
'artilizer additions In Forest-Soil Relationships in
North America Papers presented at the Second North
American Forest Soils Conference. August 1963 Oregon State
University, Corvallis p 95-104.
9. Davey, Charles B. 1970 North Carolina forest nutrition
research problems In Nutritional Problems and Practices
on Forest Land. A Symposium sponsored by the College of
Forest Resources, University of Washington, Seattle Mimeo,
unnumbered leaves
10 Department of Forestry and Rural Development 1967 Review of
forest fertilization in Canada Forestry Branch, Department
of Forestry and Rural Development, Ottawa Departmental
Publication No 1186. 175 p
11 Evans, James 1972 Aerial forest fertilization with fixed wing
aircraft. In- Proceedings - Forest Fertilization Workshop
Sponsored by the Northwest Forest Soil, To-icil at Camas,
Washington, October 22, 1972 Report No 18, State of
Washington Department of Natural Resources, Olympia p. 60-66
12. Gentle, Wallace. 1970 General corrective practices—Australia
In. Nutritional Problems and Practices on Forest Land A
Symposium sponsored by the College of Forest Resources,
University of Washington, Seattle. Mimeo, unnumbered leaves
13. Gessel, Stanley P. 1962. Fertilizers and forestry Plant Food
Review 8(3) 10-12
14 1969 Introduction to forest fertilization
in North America Forest Industries 96(10) 26-28.
15 Hagner, Stig 0. 1967 Forest fertilization in Sweden Pulp and
Paper Magazine of Canada 68(10) WR 428-430.
52
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16 1967 The evolution of forest fertilization in
Sweden. In. Forest Fertilization. Proceedings of the Vth
Colloquium of the International Potash Institute Berne,
Switzerland, p. 41-48
17 Holmen, H. 1967. Forest fertilization in Sweden. In. Forest
Fertilization Proceedings of the Vth Colloquium of the
International Potash Institute. Berne, Switzerland p. 291-297.
18 1971 Personal communication dated November 19,
1971. The Royal College of Forestry, Stockholm, Sweden
19. . 1971. Skogsgodsl--ng i Svenge (Summary Forest
fertilisation in Sweden ) Sartryck ir Kungl. Skogs-och Lant-
bruksakademiens. Tidskrift 1971.3 7 p.
20. Holstener-.Jorgensen, H. 1967 Experiences obtained from fertili-
zation of Norway spruce in Denmark. In Forest Fertilization
Proceedings of the Vth Colloquium of the International Potash
Institute. Berne, Switzerland p 275-281
21. Institute of Forest Products. 1970. Forest fertilizer research
in the Douglas-fir region of the Pacific Northwest Phase II.
Research Proposal College of Forest Resources, Umversit,,
of Washington, Seattle 12 p
22 1971 Regional Forest Nutrition
Reaearch Project 1970-71 Annual Report College of Forest
Resources, University of Washington, Seattle 23 p.
r
23 Jerven, 0. 1967. A brief summary on the evolution of forest
fertilization in Norway In Forest Fertilization.
Proceedings of the Vth Colloquium of the International
Potash Institute Berne, Switzerland p. 49-51.
53
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24 Kawana, Akira. 1969. Forest fertilization in Japan. Journal
of Forestry 67 485-487
25. Mauge, J. P. 1967. Economic results of forest fertilization in
the area of Landes de Gascone In Forest Fertilization
Proceedings of the Vth Colloquium of the International
Potash Institute Berne, Switzerland p 341-344.
26. Mayer-Krapoll, Hermann 1956 The use of commercial fertilizers--
particularly mtrogen--in forestry Translated and published
in the United States by Nitrogen Division, Allied Chemical and
Dye Corp., N.Y 111 p
27. Moore, Duane G 1970 Nitrogen in the environment--a critical
IOOK In Nutritional Problems and Practices on Forest
Land A Symposia1" sponsored by the College of Forest
Resources, University of Washington, Seattle Mimeoh unnumbered
leaves
28. Norns, Logan A and D G Moore. 1971 The fate and entry of
forest chemicals in streams In Proceedings of a Symposium
Forest Land Uses and Stream Environment 1970. Oregon State
University, Corvallis. p 138-158
29. O'Carroll, N. 1967. Forest fertilization in the Republic of
Ireland. In Forec<- Fertilization Proceedings of the
Vth Colloquium of the International Potash Institute Berne,
Svntze-land. p. 271-21\
i
30 Osara, N A 1967. Trends in wood production and consumption,
anu the role of forest fertilization In Forest Fertiliza-
tion. Proceedings of the Vth Colloquium of the International
Potash Institute. Berne, Switzerland p 14-22
54
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31. Paarlahti, Kirwo. 1972. Personal communication dated Parch 13,
1972 The Finnish Forest Research Institute, Helsinki,
Finland.
32. Pritchett, W L. and H Hanna 1969. Results to date, potentnl
gains in Southeabt generate "cautious optimism " Forest
Industries 96(11) 26-28.
33 Public Land Law Review Commission 1970 One third of the Nation's
land A Report to the President and to the Congress by the
Public Land Law Review Commission Washington, DC 342 p
34. Rnhinen, P. 1967 The importance of tne forest and wood for
the Finnish economy In Forest Fertilization Proceedings
of the Vth Colloquium of the 'nternatioial Potash Institute.
Berne, Switzerland p 18-22.
35. Salonen, L. K 1967 Evolution of forest fertilization in
^inland In Forest Fertilization Proceeoings of the
Vth Colloquium of the International Potash Institute
Berne, Switzerland p 39-40
36 Shibmoto, Takeo 1957 Fertilizing forest lanes Translated
and published by Allied Cnemical and D>c> lorp , N. Y 35 p.
37. Stefferud, Alfred (Ed ). 1957. Soil The 1957 yearbook of
agriculture. U S. Department of Agriculture, Washington,
D. C. 784 p
38. Strand, Robert F 1C71 Forest fertilization in northwestern
U.S A. and western Canada Unpublished manuscript. 12 p
39. and R. F Miller 1969 Douglas-fir growth can
be increased report from Pacific Northwest shows Forest
Industries 96(10) 29-31
55
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40. Swan, H. S. 0. 1965. Reviewing the scientific use of fertilizers
In forestry. Journal of Forestry 63:501-508.
41. . 1969 Eastern Canada probes less costly wood
trees on good sites, near mills, fertilized Forest Industries
96(11) 32-35
42 . 1971. Personal communication dated November 2,
1971. Pulp and Paper Research Institute of Canada, Pointe
Claire, Canada.
43 Tamm, C. 0. 1968 The evolution of forest fertilization in
European silviculture. In- Forest Fertilization theory
and practice Symposium on Forest Fertilization, April 1967.
Tennessee Valley Authority, National Fertilizer Development
Center, Muscle Shoals, Alabama p. 242-247
44. U. S Forest Service 1955 Timber trends in the United States.
1). S. Dept Agr , Forest Resource Report No. 17. Washington,
D. C. 255 p.
45 White, Doraio P. 1969 Research and development in forest
fertilization in Northeast and Midlist Forest Industries
&o(9) 29-31
46. Will, Graham. 1971 Personal contact, December 6, 1971, at
Oregon State University Sanior Scientific Officer, Forest
Research Institute, New ZeaTand Forest Service, Rotorua,
New Zealand.
56
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SECTION VII
APPENDIX WATERSHED STUDIES
1. Aubertin, G. M. 1971 Influences of forest fertilization on
quantity and quality of streamflow Forest Service, Timber
and Watershed Laboratory, Parsons, West Virginia Progress
Report 4300-FS-NE-1602025. 28 p.
2. Burroughs, Edward R., Jr and H. A Froehlich 1972 Effects of
forest fertilization on water quality in two small watersheds
Final draft for Bureau of Land Management Technical Note,
Portland, Oregon. 17 p
3. (Clock, 6. 0. 1971. Streamflow nitrogen loss following forest
erosion control fertilization. Pacific Northwest Forest
and Range Experiment Station, Forest Services Research
Note PNW 169, Portland, Oregon 9 p
4. Malueg, K. W., C. F Powers, and D F. Krauczyk 1972 Effects
of aerial forest fertilization with urea pellets on nitrogen
levels in a mountain stream. Northwest Science 46(1) 52-58
5 McCall, Merley 1970. The effect;, of aerial forest fertilization
on water quality for two streams IP the Capitol Forest
Washington Sv.ate Department of Ecology, Olympia, Washington
20 p
6. Moore, Duane G. 1971 Behavior and fate of fertilizer nitrogen
apTlied to forested watersheds U S Forest Service Contri-
bution Project Report, Western Regional Research Proje:t,
Progress Report Forestry Sciences Laboratory, Corvallis,
Oregon. 5 p
7. Thut, Rudolph N. 1970. Effects of forest fertilization on surface
waters Weyerhaeuser Company, Research Division, Longview,
Washington. Project Number 045-0073 29 p
57
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SELECTED WATER
RESOURCES ABSTRACTS
INPUT TRANSACTION FORM
1 Report ffo
EPA-R2-72-016
< Title
FOREST FERTILIZATION. A State-of-the-Art Review and
Description of Environmental Effects
1 Autaorfi)
Wi n lam A Grotnan
9 Organisation
Environmental Protection Agency, Corvallfs, Oregon
National Environmental Research Center
Pacific Northwest Water Laboratory
Spoaiorinf Orgtamtioa
Supplementary Notes
3 Acctssioo Flo
S feyoitOate July 1972
6
B Performing Crgamtetioa
Report Ko EPA-R2'72"0?6
10 Pic'cctNo
Program Element 1B2037
II Contract(Grant No
12
li
13 Tj^f of Report tnd
Prrtod Covered
State of Art
through 1971
16 A bit net
Information pertaining to the concepts, scope, and methods of forest ferti'f-
zation in various nations and regions of the world ha*; been compiled from available
sources Factors influencing development to present, status, possible trends, and
Impacts on t*ater quality are •(iscussed.
Results of co-ripleted forest fertilization-water quality studies have bean
summarized and evaluated, and the status of current water quality stuoies is
X described. Recommendations for state-of-the-art reviews and essential research
/efforts are presented (Greman—EPA)
17e Descriptor*
*Forest management, *FertIlization, *Envlromnental effects, Silviculture
Forest soils, Soil treatment
17b Identifier!
*Forest fertilization, *Water quality studies
17c COWRR Field £ Croup 05B ,05C
It A visibility
rWm. A. Grontan
19 Security Cltif
(Report)
20 Security Cteu
(Post)
21 No ol
I'age*
V
U Puce
Send To
AATCR RESOURCE'S. -sClfcST ft<~ ir.FOnMAT ON CENTER
US DEPARTMENT OF TMC I
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