Title: Potassium cycling in a fertilized slash pine (Pinus elliottii var. elliottii Engelm) ecosystem in Florida /
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Title: Potassium cycling in a fertilized slash pine (Pinus elliottii var. elliottii Engelm) ecosystem in Florida /
Physical Description: xi, 133 leaves : ill. ; 28 cm.
Language: English
Creator: Voss, Roylyn Lee, 1939-
Publication Date: 1975
Copyright Date: 1975
 Subjects
Subject: Slash pine   ( lcsh )
Potassium fertilizers   ( lcsh )
Soil Science thesis Ph. D
Dissertations, Academic -- Soil Science -- UF
Genre: bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Thesis: Thesis--University of Florida.
Bibliography: Bibliography: leaves 123-132.
Statement of Responsibility: by Roylyn Lee Voss.
General Note: Typescript.
General Note: Vita.
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Bibliographic ID: UF00098321
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: alephbibnum - 000355569
oclc - 02274401
notis - ABZ3810

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POTASSIUM~ CYCLING IN A FERTILIZED SLASH PINE
(Pinus elliottii var. elliottii Engelm.)
ECOSYSTEM IN FLORIDA











B~y

Roylyn Lee Voss


A DISSERTATION PRESENTED TO THE GRADUATE COUNCIL OF
THE UNIVERSITY OF FLORIDA IN PARTIAL
FULFILU4ENT OF THE REQUIREHlENTS FOR THE DEGREE OF
DOCTOR OF PHIILOSOPHIY








UNIVERSITY OF FLORIDA


1975


















ACKNO~L EDGEM1ENTS


I wish to acknowledge the assistance and encouragement of the

many people at the University of Florida thiat have made my stay a

pleasant one. In particular, my thanks must go to Dr. W.L. Pritchett,

my committee chairman, and to the members of my committee, Dr. T.L.

Yuan, Dr. W.H. Smithi, and Dr. J.A. Cornell for their guidance and

encouragement, both in my course wrork and in my research.

I especially wish to thank Ms. MIary MlcLeod for her encourage-

ment and assistance in the laboratory, Dr. Johin Feaster of the Animal

Nutrition Laboratory for the use of the atomic absorption spectro-

photometer, and my wJife for her assistance as technologist in the

Animal Nautrition Laboratory and for her efforts in typing the draft

of this dissertation.

For the financial support of this project I am indebted to the

Cooperative Research in Forest Fertilization (CRIFF) program and its

many members.





TABLE OF CONTENTS


Pa7,e

ii



lXi

ix


1

3

3

3

3



4

4

4

5

5

6

6

7

9

9

11

12


ACKNOW~LEDGE~MENTS ..............

LIST OF TABLES

LIST OF FIGURES

ABSTRAlCT

INTRODUCTION ...........

LITERATURE REVIEW .............

The Role of Potassium in Plant Nutrition ........

Physiological Function of K ............

Potassium Uptake.......... .

Role of K in Disease and Insect Resistance
in Forests . . .. . .

Distribution of K in Trees ...... .....

Interrelations of K and Other Nutrients ......

Potassium as a Component of the Physical Environment ..

Mineralogical Sources of K ............

Potassium in Florida Forest Soils .........

Leaching of K ...........

Meteorological Inputs of K and Other Nutrients ....

Response of Forest Trees to K Fertilization ......

Geographical Areas of K Deficiencies .......

Deficiency Symptoms in Trees ...........

Evaluation of Soil K Supplies ..... .....














Page

Tissue K Concentration .. . . . ... 13


Extent of K Fertilization in Pine Production .. 14


Biomass and Nutrient Cycling in Forests with Reference
to K .. .. .. .. .... .. .. 15


Biomass Production in Forests .. .. .. .. 15


Nutrient Cycling in Forests .. .. .. . 17


Summary . .. .. .. .. .. . 21


MA~TERIALS AND METHODS . .. . . . . .. . 24


Experimental Site . ... .. ... .. .. 24


Location and Description of Stand . .. .. .. 24


Soil . . . .. . .. .. 25


Climatic Data .. . .. .. .. .. 26


Experimental Methods . .. . . ... 26


Experimental Design . .. .. . .. 26


Sampling Methods . ... . .. .. .. 27


Laboratory Analysi~s .. .. .. . .. ... 30


Growth Data .. ... .. .. .. .. .. 31


Whole Tree Harvest . .. .. .. .. .. .. 32


Statistical Treatment of Data .. .. .. .. 33


RESULTS AND DISCUSSION ... . . . .. .. 34


Precipitation Inputs into the System .. ... .. 34


Growth Response in the Fertilized Plantation .. .. 38


Volume Increment Response to Treatment .. .. 38


Needle Length . ... .. .. .. .. 41


Effect of Fertilization on K and Other Nutrient
Contents in Tissue .. .. .. . .. 41


K Concentration of Tissue as Influenced by Time
and Fertilization ..... . . .. . 41












Pag

Na, Ca, Mg, and P Concentration of Tissue
as Influenced by Time and Fertilization .. .. 53

Leaching of Nutrients from the Trees .. .. .. .. 56


Throughfall Nutrient Concentrations . .. .. .. 56

Stemflow L~osses from Trees .. .. . ... 58


Throughfall and Stemnflow Quality and Quantity
as Affected by Amounts of Rainfall .. .. .. 60

Litterfall . . ... .. .. 64


Estimates of Annual Litterfall . .. .. .. .. 64

Effect of Fertilization on Litter Nutrient
Concentration . .. . . .. 65

Residence Time of K and Other Nutrients in the
Forest Fl~oor . ... .. . .. 65

Nutr-ient Status of Soil and Soil WJater Following
Fertilization .. .. .... .. . 68


Changes in Soil K with Depth and Time .. .. .. 68

Changes in Other Nutr-ients with Depth and Time . 75

Soil Water and Ground Water Nutrient Concentration 75


Estimation of Water Use by the Plantation . ... 79

Rainfall Influences on Soil r.ater and Ground Water 80


Estimates of Leaching Loss .. .. .. .. .. 80

Fertilizer Effects on Selective Ground Cover Plants . 80


Biomass and Nutrient Content Changes in Saw
Palmetto . . ... .. .. . 80


Biomass and Nutrient Content Changes in
Bracken Fern .. ... . . . 81

Biomass and Nutrient Concentration in the Tree
Component ..... . . 83

Total Tree Harvest . . . . . . 83

Biomass Distribution in the Above Ground Portion
of the Trees .. . .. . . 83














rage

Comparison of Nutrient Contents in Various
Parts of the Tree . .. ... . .. 87


The Nutrient Cycle .. .... .. .. 90


The K Cycle in Slash Pine . ... .. .. 90


The Effect of Applied Fertilizer in the K Cycle . 94


Cycle of Other Nutrients in the System .. .. 95

The Recovery of Applied K in the Slash Pine
Ecosystem .... .... . .. 97


Long-Term Implication of the K Cycle .. .. .. 99

SUMMARY AND CONCLUSIONS . ... .. ... 100

APPENDIX . . ... . .. . 103

LITERATURE CITED . ...... ... . .. 123

BIOGRAPHICAL SKETCH . .... .. . .. 133





LIST OF TABLES


Table Page

1 A summary of some atmospheric nutrient inputs
reported worldwide .. .. ... .. . 8

2 Volumes and nutrient concentration of rainfall . .. 35

3 Analysis of variance of volume increment response . 39

4 Mensuration data averages on plantation by treatment 40

5 Variation of flush needle length with time (age) and
treatment during the 1973 growing season. (9/14/73)
represents date of maximum needle elongation .. .. 42

6 Summary of tests of significance for K concentration
of tissue by type of tissue, treatment, and date of
sampling .. . ... .. . .. 49

7 Tissue K compared by Dunnett's test and linear
regression ... .. . 50

8 The effect of treatment and type of tissue on the mean
K concentration for sampling dates ... .. .. 52

9 Summary of tests of significance for Na, Ca, Mlg, and
P concentrations of tissue by type of tissue and
treatment effect ... . .. . .. 54

10 Average Na, Ca, Mig, and P concentrations in slash pine
tissue .. .. ...... . .. 55

11 Annual nutrient contents of throughfall . .. ... 57

12 Annual nutrient loss from trees by stemflow . ... 59

13 Regression equations of throughfall volume on
throughfall nutrient concentrations . .. ... 61

14 Annual nutrient content of litter from slash pine . 66

15 Quantities of litter, forest floor, and nutrient at
conclusion of experiment .. ... . .. . 67

16 Summary of tests of significance for sampling time and
nutrient concentration of soil by treatment and depth 70











Table

17 Average Na, Ca, Mlg, and P concentrations in soil by
sample date and depth ... .. ... . . 76

18 Soil water and groundwater nutrient concentrations . 77

19 Ground cover biomass and nutrient concentrations .. 82

20 Biomass, biomass distribution, and mensuration date on
harvested trees . .... . . . 86

21 Concentration of nutrients in biomass and forest floor 88

22 Average tree biomass and nutrient content distribution
in the plant tion . . .. . . 89

23 Biomass and nutrient contents during the 14th year of
tree growth . . . . . 92

24 Net recovery of K from applied fertilizer in the system 98

25 Soil chemical and physical properties ... . ... 104

26 Extractable soil nutrients by date, treatment and depth 105

27 Average concentration of K in foliage .. .. ... 110

28 Multiple regression equations for % K in various
tissue components . .. .. . . . 111

29 Average concentration of Na in foliage . .. ... 112

30 Average concentration of Ca in foliage .. .. .. 113

31. Average concentration of Mg in foliage .. .. .. 114

32 Average concentration of P in foliage .. .. .. 115

33 Volume of throughfall and K and Na concentrations .. 116

34 Throughfall volumes and Ca, Mg, and P concentrations. 118

35 Needle litter weights and nutrient concentrations .. 119

36 Other litter weights and nutrient concentrations .. 121.


V111

















LIST OF FIGURES


FigurePayr

1 Potassium cycle in Scots pine .. .. .. .. .. .. 22

2 A systems model to mineral cycling .. .. . ... 23

3 Precipitation at Austin Cary Memorial Forest and
ground water levels at selected dates ... .. .. 37

4 Tissue K concentration with time in treatment KO .. 44

5 Tissue K concentration with time in treatment KO+ . 45

6 Tissue K concentration with time in treatment K48+ . 46

7 Tissue K concentration with time in treatment K96+ . 47

8 Tissue K concentration with time in treatment Kl92+ . 48


9 Regression of throughfall and stemflow volumes on
rainfall volume .. .... . ... 62

10 Throughfall, rainfall, and groundwater level in the
plantation .. .... .. . . 63

11 Distribution of K in soil by treatment, time, and depth 71

12 Comparison of inner bark tree volumes by stem
analysis and local volume formula .. .. . 85

13 The K cycle in 13-year-old slash pine .. ... .. 93





Abstract of Dissertation Presented to the Graduate Council
of the University of Florida in Partial Fulfillment of the Requirements
for' the Degree of Doctor of Philosophy


POTASSIUMI CYCLING, IN A FERTILIZED SLASH PINE (Pinus elliottii
var. elliottii Engelm. )ECOSYSTEMI IN FLORIDA

By

Roylyn L~ee Voss

June, 1975

Chairman: Wil~liam L. Pritchett
Major Department: Soil Science

The effect of applied K on the growth and K; cycle in a 13-year-

ol~d slash pine plantation was examined. Potassium chloride at rates of

0, 48, 96, and 192 kg K/ha with a basal application of diammonium

phosphate (DAP) at 224 kg/ha was applied to 0.04 ha plots. An addition-

al treatment receiving no fertilizer was established as a check plot.

There were three replications of the five treatments. Annual nutrient

input from rainfall to the system under study was 1.6 kg K/ha, 7.2 kg

Na/ha, 4.6 kg Ca/ha, 1.3 kg Mg/ha, and 0.2 kg P/ha.

While no growth response to K treatments was detected, DAP in-

creased the first flush needle lengths in the 1973 growing season by

10%.

Tree tissue, litterfall, throughfall, stemfall, soil, soil

water, ground water, and ground cover nutrient concentrations were ex-

amined throughout the 17-month experimental period. Final nutrient

contents were determined by total tree harvest. Root biomass and nu-

trient contents were estimated using published data for slash pine

growing on similar soils.





Differences in K concentration in current and new growth were

significant within 30 days following treatment, with the high K con-

centrations corresponding to the high K treatment rate. Sodium, Ca, Mg,

and P concentrations were not affected by K or DAP application.

Losses of nutrients from the tree crowns by leaching and litter-

fal~l were small and amounted to only 4 to 8 kg K/ha/yr. Calcium losses

approached 25 kg/ha/yr, while Mg and P losses were lower than K.

Throughfall P contents were smaller than rainfall and indicated direct

foliar uptake of P from the rainfall.

Up to 82% of the K in the oldest needles on the tree appeared

to be translocated from the needles to other parts of the tree before

abscission. Litterfall did not lose additional K as it was incorporated

into the forest floor.

Total tree biomass amounted to 100 t/ha at the conclusion of the

study. Volume increment determinations provided an estimate of

10 t/ha/yr net increase in tree biomass for the duration of the experi-

ment. Ground cover provided little total biomass, but contained 29% as

much K as the total trees.

Recovery of applied K ranged from 68% of the lowest K applica-

tion rate to 29% of the highest application rate.
















INTRODUCTION


Miineral cycling plays an important role in the continued mainte-

nance of nutrition in forest ecosystems, as well as contributing to the

processes of forest soil development. Under cond itions of nutritional

stress, whether through natural. deficiencies in the system, by continued

depletion by harvest, or by other means, the mineral cycle must adjust

to low nutrient levels. Premature loss of needles, visual foliage

changes, and suppressed growth are visual signs of adjustments to nutrient

deficiencies in Pinus species, particularly with phosphorus (P)

(Pritchett and Llewellyn, 1966; Will, 1968), but also common symptoms in

potassium (K) deficient areas (Heiberg and White, 1951; Raupach and Hall,

1972). In less severe cases of nutrient deficiencies, growth response to

added K is taken as presumptive evidence of deficiency (Pritchett and

Smith, 1969; Hall and Parnell, 1961).

Growth responses in slash pine are well documented for nitrogen

(N) and P in marine deposited sands of the southeastern Coastal Plain of

the United States (Pritchett and Llewellyn, 1966) and current use of N

and P fertilizers is increasing to meet the increasing demand for pulp

and lumber (Pritchett and Cray, 1974). Potassium deficiencies are less

evident in this area, although K levels in foliage and soil are sometimes

extremely low. It is not yet known how increased tree growth resulting

from P and N fertilization will affect the K nutrition of forests of this

area, but in a series of experiments conducted by the Cooperative

Research in Forest Fertilization (CRIFF) program little or no growth





response was obtained when additions of 88 kg/ha of K were made to N

and P fertilizer treatments.

Large areas of the Coastal Plain are currently in forests, with

over half of the approximately 80 million forested hectares in the 13

southeastern states supporting pine forests. In Florida alone, it is

estimated over 4 million ha of slash pine forest on "flatwood" soils

will respond to application of N and P fertilizer (Pritchett and Gray,

19 74) These soils are characterized by coarse textures, acid reac-

tion, inherently low levels of fertility, and somewhat poor drainage

(drainage class 2) (Pritchett and Smith, 1974). Because of the low

total K contents and absence of K-bearing primary minerals in these

soils (Zelazny and Carlisle, 1971), the ability to supply K to forest

trees over long periods is of interest, particularly in light of

responses to K found in agronomic crops in Florida. In addition,

shortened rotation times and whole tree harvest methods may result in

a rapid and serious deplation of nutrients on forest sites of

naturally low fertility (Malkonen, 1973).

The objectives of this study were to:

1. Determine the response of slash pine to applied K on

a flatwoods soil.

2. Examine the K cycle in reference to foliage, litter-

fall, throughfall, stemflow, rainfall, soil water,

ground water, and soil nutrient concentrations as

affected by K fertilization.

3. Model the long range K needs for slash pine production

on flatwood soils.





LITERATURE REVIEIJ


UTe Role of Potassium in Pl~ant Nutrition


Physiological Function of K

While N and P are constituents of plant protoplasm and undergo

many complex organic combinations in the synthesis of compounds neces-

sary to plant growth, K does not. Potassium is generally found as a

soluble inorganic salt in tissues in relatively large amounts and ap-

pears to have rather specific functions that cannot be replaced

completely by even closely related elements, such as sodium (Na) and

lithium (Li) (Tisdale and Nelson, 1966; Mustanoja and Leaf, 1965;

Baule and Fricker, 1970).

These functions include;

a) production and translocation of carbohydrates,

b) conversion of reduced N compounds to protein,

c) uptake of nitrate and other anions, water uptake and
transpiration, and

d) enzymatic action enhancement. Potassium and other
monovalent cations may serve as cofactors for as many
as 46 known enzymes for animals, microorganisms, and
higher plants (Cauch-, 1972).


Potassium Uptake

Potassium presumably is taken up by plants through a process

of "active transport" that allows uptake against a concentration

gradient (Epstein, 1955). Some evidence suggests that mycorrhizal as-

sociations enhance K uptake in trees (Harley, 1959; Rosendabl, 1942;

Baule and Fricker, 1970).





Role of K in Disease and Insect Resistance in Forests

WJhile K is generally credited with increased disease and insect

resistance in trees (Weetman and Hill,, 1973), results have been

ambiguous in many CRIFF experiments. Potassium added as a supplement

to 88 kg/ha rates of N and P reduced insect damage from 17% without

added K to 12% in 5 locations, b;ut had little effect on the incidence

of Cronartium fusiforme (Pritchiett and Smith, 1972). It was also

found that K alone has been able to give height growth increases

without concomitant increase in rust infection. When N was added with

K, higher rust incidence often resulted over that of the K alone

(Pritchett and Smith, 1972).


Distribution of K in Trees

Because K occurs in trees in the ionic form, it appears to be

quite soluble and leaching of K from foliage occurs readily during

precipitation (Tamm, 1951; Will, 1955; and Cassiday, 1966). Because of

its mobility, K; tends to concentrate in the active growing portion of

the trees. New flushes, buds, and growing root tissue are generally

higher in K concentration than older tissue (Madgw~ick, 1963; and WJhite,

1964). Translocation within the plant from one tissue to another is

commonly observed and at times of plentiful supply, K may be taken up

in greater quantities than is needed by the plant, leading to the

phenomenon of "luxury" consumption. Only when quantities of K( reach~ a

concentration causing salt injury will toxicity occur.


Interrelations of K and Other Nutrients

rhile K is closely related to Na, little evidence of substitu-

ion of Na for K: in forest trees hias been found. Only small responses





due to Na application has been observed in red pine (P.resinosa) in K

deficient soils in New York (Madgwick, 1961). Potassium and Na uptake

appear to be accomplished separately and evidence suggests that

calcium (Ca) is required for the active uptake of K (Epstein, 1955) in

addition to the physiological function relationships already noted for

other nutrients.


Potassium as a Component of the Physical Environment


Mlineralogical Sources of K

The average K content of the earth's crust is 2.4%, but the

content in soil is variable and may range from only a few hundred

parts per million (ppm) in quartzite sands to more than 24,000 ppm in

soils containing large amounts of K-bearing minerals (Tisdale and

Nelson, 1966).

The primary minerals most commonly associated with soil forma-

tio ar K eldpar KA~i308; muscovite, H2KAl3(SiO4 3; and biotite,

(H,K)2(Nrg,Fe)2Al2(SiO )3 (Tisdale and Nelson, 1966). The feldspars

are the most abundant of all minerals, making up approximately 57% of

the earth's crust. The K feldspars contain an average of 14% K. The

mica group of phyllosilicates (muscovite and biotite) are less

abundant and make up 5.2% of the earth's crust and contain 8 to 10% K

(Berry and Mason, 1959).

The relative availability of the K contained in these minerals

follows the sequence: biotite > muscovite > feldspar. During soil

weathering illite or hydrous mica which contains 3 to 5% K may form.

Other clay minerals such as interstratified mica and montmorillonite

may contain up to 0.5% K (Tisdale and Nelson, 1966).





While K in primary minerals is generally not available to

plants, it has been shown to be somewhat water soluble in finely ground

minerals. Carbonated water is effective in removing K from finely

ground minerals (Rich, 1968), and mycorrhizal fungi have been shown to

utilize K from minerals in association with forest tree roots (Harley

and Wilson, 1959; Voigt, 1965).

Potassium may be fixed by certain clay minerals into relatively

unavailable forms which allow the buildup of total K; in the soil, while

reducing the readily available K. This is beneficial in soils that are

low in cation exchange capacity (CEC) and that contain small amount of

K-bearing minerals (Volk, 1934; Vleck et al., 1974).


Potassium in Florida Forest Soils

Pine production in the southern Coastal Plain is predominantly

in the flatwoods areas (Pritchett and Smith, 1974). Quartzite sands

dominate the area, and often contain less than 5% silt plus clay and

little or no detectable K-bearing primary minerals. The clay fractions

of the surface horizons contain only small amounts of intergrade clay

minerals, but increase slightly in amount with depth (Zelazny and

Carlisle, 1971).




Total quantities of K in flatwood soils range from 50 to 100

ppm with less than 25 ppm extractable with N NH40Ac buffered at pH 4.8.

The low CEC, low clay, and low organic matter contents would not appear

to be conducive to retention of K in the flatwood soil. Nevertheless,

greater than 50% of K applied as KC1 at 90 kg/ha has been shown to be

retained in surface soils undergoing leaching studies in soil columns

after passage of 50 cm of water (Voss, R.L., unpublished). Under field











conditions th~e leaching losses of K: due to prescribed burning and remov-

al of forest cover appear to be relatively low (Wells, 1971; Gessel and

Cole, 1965). Application of urea has also been shown to reduce the

leaching of K( in Leon soil supporting slash pine in pot experiments

(Sarigumba, 1974).


Meteorological Inputs of K and Othler Nutrients

The importance of nutrients in rainfall to nutrient cycling has

been an item of conjecture for over a hundred years (Wetsel~aar and

Hutton, 1963). Numerous early studies have had varied results, but it

seems certain that both anion and cation concentrations are generally

less than 1 ppm and contribute less than 1 to a few kg/ha/yr of

nutrient to a system except in a few particular cases as summarized in

Table 1 (Attiwill, 1966; Tamm, 1951; Nye, 1961; Miller, 1968;

Duvigneaud and Denaeyer-De Smet, 1970; Cole et al., 1967; Wetselaar and

Hutton, 1963).

Atmospheric inputs can be classified as wet deposition and dry

deposition. Wet deposition includes condensation of rainfall around

particulate matter and the interception of particles by raindrops. Dry

deposition occurs as sedimentation of particulate matter through the

atmosphere and by impaction of particulate matter upon obstacles in the

path of the windflow. Sodium, Ca, Mg, P, and K exist in the atmosphere

only in particulate form, originating from smoke, mineral dust, sea

spray, and other aerosols (White and Turner, 1970). Dry deposition is

difficult to assess, especially under forest cover, but attempts have

been made to separate the foliar dust contribution from that leached

from the tree crowns by using artificial entrapments of netting to













TABLE 1. A summary of some atmospheric nutrient inputs reported world-
wide.


Annual
Location Rainfall K Na Ca MgP P Source
cm ----------- Kg/ha/yr ----------


1970)


97 2.0 16.8 2.7 5.4 tr. (Attiwill,
1966)


Australia


171 2.8


165 17.8

120 5.2




-1.6-11.7


6.7 6.1 .28 (Carlisle et
al., 1967)

12.9 11.5 .42 (Nye, 1961)

5.1 2.0 .2 (Voss, R. L.
Iinpublished)


- -(O'Carroll
and M~cCarthy,
1973)


England


Gh-ana

Hawaii




Ireland


New Zealand 92 .3-.9 1.1


S2


(Wetselaar
and Hutton,
1963)


New Zealand


5.0 54.0 7.0 10.0 .3 (Mliller, 1968)


2.8 .7 .2 (W(ells and
Jergensen,
1973)

8.1 10.4 1.5 (Tarrant et
al., 1968)


North Carolina


1.6


Oregon


Sweden


95 1.9 5.6 3.5 .91 .07 (Nihlajard,











simulate the foliage (Schlisinger and Reiner, 1974; Niblajard, 1970) and

special dust collectors (Wh-ite and Turner, 1970; Woodwell and Whittaker,

1967). In general, contributions of nutrients from dry deposition are

considerably smaller than from wet deposition and are usually collected

along with the wet deposition in open rainfall collectors.


Response of Pine Trees to K Fertilization


Geographical Areas of K Deficiencies

Growth responses to fertilizer K in pine forests have been

reported throughout the world (Leaf, 1967). In general, K deficiency

occurs most often on acid sandy soils that are low in organic matter

and low in CEC. Previously cropped lands, leached soils, and eroded

soils may show K deficiency when planted to pine.

One of the most thoroughly studied areas of K deficient forest

soils occurs in the glacial outwash soil areas of northern New York.

Over 30 years of extensive research exists on these sandy soils where

red pine (P. resinosa) and white pine (P. strobus) show marked responses

to applied K. Early application of 224 kg/ha of KCl to 5- and 6-year-

old trees corrected deficiency symptoms and increased the tissue K

content from less than 0.34% to 0.74%. Response was still measurable

after 16 years of growth (Heiberg and White, 1951).

In some of these soils the presence of a fine textured soil

layer at depths of as great as 3 m enhanced growth by improving

moisture relationships and preventing the leaching of K. Without ad-

ditions of K, the foliage of trees growing in the soil area with the

fine-textured layer had K concentrations of 0.35% while the foliage

from trees growing in the areas without such a layer had K concentra-





tions of only 0.27% (White and Wood, 1958). Even those sandy soils

shown to contain 2 to 3% total K; have shown responses to K applica-

tions due to the relative unavailability of the K in the primary min-

erals (White and Leaf, 1964).

Similar coarse textured soils in Canada hanve also shown

improved growth of pine with applications of up to 224 kg K/ha. Two

years were required for a significant response in diameter increase

and three years for height responses in 20-year-old red pine plant-

ings (Gagnon, 1965).

In Denmark and throughout the Scandinavian countries, ferti-

lizer applications of P and N appear to have significantly increased

incidences of observable K deficiency symptoms (Holstener-Jdrgensen,

1964).

Poorly drained silt loom soils in eastern Australia and fine

sandy loams and loamy sands in western Australia have both been shown

to be K deficient for radiata pine of all ages (Hall and Raupach,

1963; Raupach and Clarke, 1972). In Ireland, K deficiency is found on

peat lands that have little or no primary K mineral sources and are

far enough removed from the ocean that levels of K in the precipita-

tion are insufficient to maintain K supplies for normal tree growth

(0'Carrol and McCarthy, 1973).

In the coarse textured coastal plain soils of the southeastern

United States K was not originally considered a limiting factor in

pine production (Pritchett and Llewellyn, 1966; Walker, 1958). Mlore

recently, as additions of N and P were found to enhance growth on the

less well drained soils, K responses in young slash pine and loblolly

pine are being observed. Approximately 40% of a series of 36 experi-





ments with slash pine placed throughout the southeast have shown initial

response to additions of 88 kg/ha of K when applied with N and P as

compared to N and P applied alone (Pritchett and Smith, 1972),

but these gains have not persisted as the trees attained sufficient size

to more thoroughly exploit the site (Pritchett and Smith, 1974).

Deficiency Symptoms in Trees


Deficiency symptoms have been shown to occur quite rapidly when

K concentrations drop below that necessary to maintain metabolic fune-

tions. Stunting, bluish-green discoloration of needles, chl.orosis, and

copper-colored discoloration of the terminal growth, with some necrosis,

have been shown to be characteristics of K-deficient pitch pine (P.

rigida), red pine, white pine, and shortleaf pine (P. echinata) grown

in K-deficient solution cultures, with white pine showing general

chlorosis and thie rest only occasional chlorosis (Hobbs, 1944). Stunt-

ing and discoloration have also been recognized under field conditions

in Scots pine (P. sylvestris) and radiata pine (P. radiata), with the

previous years foliage yellowing as a result of the rapid translocation

of K to the actively growing portion of the plant (Hall and Raupach,

1963), particularly during the early spring flush (Walker, 1956). Pre-

mature needle cast and short needles are often described as symptoms of

K deficiency (Heiberg, Madgwick, and Leaf, 1964). Radiata pine grown

on K-deficient sites in Australia show early spring symptoms of yellow-

ing at the tips of the youngest needles immediately behind the current

shoot in the lower laterals, giving a halo appearance to the shoot

(Raupach and Hall, 1972). "U" shaped shoots have also been described

(bu~pach and Hall, 1972) as a K deficiency symptom in radiata pine in





Australia. Sulfur-induced K deficient slash pine grown on excessively

drained soils in Florida also show a yellow halo appearance (Bengts >n,

G.W., personal communication).


Evaluation of Soil K jggy lies

Soil testing has long been regarded as a rapid means of evalu-

ating the nutrient supplying ability of a soil and much effort has gone

into calibrating levels of K extracted by different test methods with a

particular crop's ability to make use of that nutrient. Originally,

total analysis served to give an approximation of the nutrient content

of a soil, but with increased understanding of soil mineralogy this was

abandoned in favor of various chemical extractants that could be cali-

brated to plant uptake.

Forest soils work has relied on test methods developed for agri-

cultural crops and often the need for a soil test that takes into con-

sideration the longer tenure of a forest crop on a given site is compro-

mised in favor of the ease of adopting methods already developed.

One method of evaluating long term K supplying power for tree

crops is boiling soil samples in N HNO3 for 10 minutes. Good correla-

tion within growth of red pine in the K-deficient outwash soils of New

York has been reported (Hart, Leaf, and Statzback, 1969).

In the southeastern United States, methods developed by agri-

cultural workers have been used extensively with varying degrees of

success and in Florida the standard method for extracting P and cations

is with N NH 0Ae buffered at pH 4.8. Levels of K found in soils by

this method range from 3 to 50 ppm with values below 15 ppm for surface

soils considered low in K for trees (Pritchett,W.L.,personal communication).





In general the use of soil test results alone for evaluation of K--

deficient areas for pine has met with little success (Walker, 1956;

Heiberg and Leaf, 1960).


Tissue K Concentration

Tissue analysis has proved to be somewhat more satisfactory

than soil analysis in predicting areas of K response in pine (Leaf,

1973), although time of sampling, sample age, tissue type and crown

position all affect the level of K found. In general, K concentrations

decrease from the top of the crown to the bottom and decrease with the

age of the tissue (White, 1954). Potassium concentration reaches a

peak in the youngest tissue during the growing season and tends to be

stable in the late fall and winter at a lower concentration than during

the growing period. It would appear that late fall sampling of middle

crown, current-year foliage is best for evaluating K status of pines

(Wells and Metz, 1963; White, 1954). TIhe incipient K deficiency level

for this foliage appears to be 0.30 to 0.50% K for pine, with optimum

levels of between 0.50 and 0.70% K (Ingestad, 1960; W~hite and Wood,

1958; Heiberg and Mahite, 1951; Stone and Leaf, 1967; Walter, 1956). In

K deficient outwash soils of northern New York state red pine responded

to K fertilization with 0.3% K concentration in the unfertilized

tissue, and increased to 0.45% and above with K fertilization at rates

of 220 kg/ha (Heiberg and White, 1951; Heiberg and Leaf, 1960). White

pine increased to 0.4% K with fertilization. Scots pine (P. sylvestris)

was found more demanding, with K deficient tissue of 0.3% K and suf-

ficient tissue 0.7 1.6% K (Ingestad, 1960).

Severe deficiency symptoms in P. radiata in eastern Victoria,











Australia, were observed when the older needles in the lower whor1 of

the crown reached a level of 0.2% K. If lower than 0.35%, growth de-

pression was detected (Raupach and Clarke, 1972). Application of

1000) kg KC1/ha gave optimum growth and increased the tissue K

concentration to 0.6% K (Hlall and Raupack, 1963; Raupack and Hal~l,

1972).

Slash and loblolly pine appear to require less K than the

above species and slash pine is the least demanding of the two. Grown

on Lakeland fine sand, both loblolly and slash pine seedlings

approached a minimum value of 0.1% K with no K added in pot culture

and a critical value of 0.2% K at application levels of 10 ppm K

(Terman and Bengtson, 1973). On a Bladen clay loam, soil water level

controlled at or near the surface of the soil gave foliar K levels of

0.58%. With 8-8-8 fertilizer applied at 1120 kg/hia, the K level in-

creased to 1.2 1.5% K (Walker, 1962).

On flatwood soils, the foliar K levels of slash pine varied

from 0.2 0.4% when N and P were added. Foliar K levels exceeded

0.4% when K was added at rates of 90 kg K/ha (Pritchett and Smith,

1974 ; Pritchett and Llewellyn,1966).


Extent of K Fertilization in Pine Production

Potassium fertilization is commercially practiced only in mid-

western Europe, Japan, and Oceana at present with minor applications to

correct specific deficient areas in New York, Canada, Australia,

Scandinavia, and Ireland. In Japan, in 1970, only 70 to 80 thousand ha

were fertilized with K at the time of establishment and another 20 to

30 thousand ha on established stands. Ten thousand ha in Oceana were











fertilized at time of establishment and 2 thousand ha on established

stands. MIidwestern Europe fertilized less thian 30 thousand ha at

establishment with 20 to 30 thousand ha of established stands ferti-

lized with K in 1970 (Hagner, 1971). With the exception of these

areas, it does not appear that any large increases in commercial use

of K in forests will occur in the next few years.


Biomass and Nutrient Cycling in Fiorests
with Reference to K


Biomass Production in Forests

It is important to know the amount, distribution, and function-

ing of tissue within a forest stand in order to evaluate the production

and nutrient needs of the total plant community.

Recent studies of total biomass production throughout the world

have been reviewed (Rodin and Bazilevieh, 1967; Art and Mlarks, 1971).

While values of over 400 t/ha of dry matter have been reported for

mature forests in both temperate and tropical areas, values of between

1.00 and 200 t/ha are more commonly found for total tree, shrub, and

herb above ground biomass. Great variability exists among reports of

biomass production, but a number of studies have shown mature Pinus spp

to reach a maximum biomass of approximately 200 t/ha when fully occupy-

ing a site (Art and Marks, 1971).

Loblolly and slash~ pine h-ave been examined for total biomass as

well as biomass distribution in the various components of the tree by

total tree harvest in the southeastern United States. Biomass of young

loblolly pine in a bottomland site in Mlississippi increased by 10 t/ha

during its fifth year of growth, increasing from 6 to 16 t/ha. Bark











percentage stayed relatively constant at 20%, with foliage decreasing

from 40 to 33% and stem wood increasing from 39 to 47% (Nelson, Switzer,

and Smith, 1968). At age 16 years, loblolly pine grown in South

Carolina had accumulated a total above ground biomass of 156 t/ha with

needles accounting for only 5% of the total, living branches 9%, dead

branches 5.5%, stem bark 9.8% and stem wood 70%. Roots added 36 t/ha

(23% of the above ground tree biomass) to the system (Wells and

Jorgensen, 1973). Other studies in the southeast have shown agreement

with these data, with needles accounting for 4 to 7% of the total above

ground biomass, stem wood averaging 70%, stem bark ranging from 10 to

12%, and living branches averaging 10 to 11% of the total (Ral~ston,

1973; Metz and Wells, 1965).

Slash pine growing on sandy loams in North Carolina accumulated

31.7 t/ha of above ground biomass by age 8 years. Stem wood accounted

for 38% of this total with stem bark, needles, live branches, and dead

branches accounting for 12, 22.5, 21, and 5.7%, respectively (Nemeth,

1973). In Louisiana bottomland soils, 8-year-old slash pine had

accumulated 50.7 t/ha on bedded sites as opposed to 34 to 37 t/ha on

flat-disced or unprepared sites. Stem wood accounted for 40 to 43% of

the total above ground biomass, with 16 to 17% bark, 16 to 22%

branches, and 20 to 23% needles. Little effect due to bedding was

found in the distribution of biomass, but the total biomass for the

bedded site was significantly greater than the disced or unprepared

sites due to the impact of an effective lowering of the water table

during the winter by bedding (McKee and Shoulders, 1974). Twelve-year-

old slash pine grown on imperfectly drained soil in Florida have shown











total above ground biomass production of 102 t/ha with 65% stem wood,

19% stem bark, 7.7% branches and 7.7% foliage. Another 27 t/ha was

found in root biomass (Mead, 1971). Fertilized slash pine growing on

a very poor drained Bladen soil in western Florida produced 190 t/ha

above ground biomass during 14 years, with 68% stem wood, 6.9% needles,

12.2% branches, and 13% stem bark (Pritchett and Smith, 1974).

In studying whole tree harvest methods of slash pine, the

total above ground biomass plus the roots in a 0.9 meter radius of

soil about the base of the tree have been examined. About 13 to *19% of

the total harvest was root material, 57 to 60% was bark-free stem to a

10 em top, 10 to 15% was stem bark, 4 to 5.5% was the remaining stem

with bark, 3 to 4% was branches, and 3.5 to 5% was needles (Koch, 1972).

Litter fall for slash pine was 1.4 t/ha for an 8-year-old stand

in North Carolina (McI~ee and Sh~oulders, 1.974). Total accumulation in

the forest floor in Florida has been reported at 19.4 t/ha in 11-year-

old slash pine (Mlead, 1971) and 39.5 t/ha in fertilized 15-year-old

slash pine (Pritchett nnd Smnith, 1974).


Nutrient Cyclin~g. in Forests

The cycling of minerals is a phenomenon that is rather unique

to forest nutrition studies as it is of minor importance in most

agronomic crop production. Cycling occurs as a function of time, and

while short term cycles may be important physiologically, it is the

seasonal and annual fluctuations that appear to be most revealing in

the study of tree nutrition.

Two basic nutrient cycles have been recognized in forest eco-

systems; (1) biological cycle, composed of thle circulation of nutrients











between the forest floor and the plant community, and (2) the geochemical

cycle, concerned with input and output of mineral elements from the sys-

tem under study (Duvigneaud and Denaeyer-De Smet, 1970). An additional

cycle has been proposed recently to account for the internal biochemical

transfer of nutrients wholly within the tree tissue (Switzer and Nelson,

1972).

The geochemical cycle includes atmospheric inputs, inputs via

the soil from geologic weathering, and transport of minerals into the

system through the ground water, both laterally and vertically. Losses

to the geochemical cycle include harvest, fires, and transport out of

the system through the ground water as leaching losses.

Rainfall inputs and the supplying ability of the soil have pre-

viously been discussed. In addition, the horizontal continuity of

ground water in forest ecosystems well away from sources of nutrient in-

put such as would occur in agricultural lands should provide a system

where gains and losses are at or near steady state conditions. That is,

ground water gains in nutrients are balanced by continuous losses.

Fertilization, burning, and harvest may upset the balance and a period

of time would then be necessary for a steady state situation to be

reestablished (Ulrich, 1973; NJells, 1971; Stone, 1971).

The biological cycle includes nutrient uptake from the soil and

forest floor, retention of nutrients within the tissue of the biomass,

and the return of nutrients to the forest floor from the biomass by

litterfall, throughfall, and stemflow. It also includes the ground

flora as part of the system.

Studies in Mississippi showed that retention of nutrients in

biomass followed the pattern of nutrient uptake, with Ca and Mg being





retained to the greatest degree in loblolly pine (Switzer and Nelson,

1972). Phosphorus and K were the most mobile in this system, being

retained in lower amounts but showing greater mobility as active parts

of the metabolic pool. The 20-year-old plantation showed 11% of the

total annual requirement for K retained and the remainder recycled. A

total of 40% of the Ca and 22% of the Mg was retained while the

balance was recycled (Switzer and Nelson, 1972). The total content of

K, Ca, Mg, and P within the tree biomass after 20 years was 98, 90, 24,

and 19 kg/ha, respectively.

Sixteen-year-old loblolly pine in South Carolina was found to

have a biomass containing 165, 187, 46, and 30 kg/ha of K, Ca, Mlg, and

P, respectively. The annual requirements at this age were 5.4 kg K/ha,

4.6 kg Ca/ha, 1.5 kg Mg/ha, and 0.9 kg P/ha (W~ells and Jorgensen, 1973).

Total above ground biomass nutrients in a 15-year-old fertilized slash

pine plantation in West Florida was 137, 221, 52, andi 24 kg/ha K, Ca, M~g,

and P, respectively (Pritchett and Smith, 1.974).

Annual returns of nutrients in litterfall were recorded for 16

to 20-year-old slash pine in Australia in which K( was returned at 2.5

kg/ha, Ca at 16 kg/ha, M~g at 6.7 kg/ha, and P at 0.4 kg/ha (Dept. of

Forestry, Queensland, 1971-72)1. Loblolly pine was found to return

greater amounts of nutrients to the forest floor in an unthinned 16-year-

old plantation than that reported for slash pine in North Carolina. An-

nual. nutrient returns as l~itterfall were 13.9 kg K/ha, 26 kg Ca/ha, 6.2

kg Mlg/ha, and 7.5 kg P/ha (Wells and Jorgensen, 1973).

Throughfall removal of nutrients from tree crowns was recognized





as early as 1814 by De Saussure. Nutrient removal as a percentage of

element present follows the sequence K > Ca > N > P (Cassiday, 1966).

Total annual removal of nutrients from radiata and loblolly crowns

ranges from 6 20 kg K/ha, 2 20 kg Na/ha, 2 8 kg Mig/ha, and 0.1 -

1 kg P/ha (Attiwill, 1966; Will, 1968; Switzer and Nelson, 1972; Wells

and Jorgensen, 1973).

Stemflow leaching, while causing only minor amounts of nutrient

loss from the crown, may be beneficial to soil microflora at the base

of the tree (Curlin, 1970).

Because K is such a mobile element, internal transfer within

the biomass may contribute greatly to the K nutrient cycle. An estimate

of up to 22% of the annual K requirement has been given for this portion

of the nutrient cycle (Switzer and Nelson, 1972) but another estimate

suggests that up to 50% of the K in the needles may be translocated into

the other portions of the tree before abscission (Wells and Metz, 7963).

The ground flora plays an important role in the nutrient cycle

in the early stages of stand development, but tends to lose its

influence during crown closure. This may be as early as 7 10 years

for loblolly and slash pine plantations, with the first few years of the

stand development dominated by the ground cover (Switzer and Nelson,

1972). Large proportions of the total K of older forest ecosystems are

sometimes found in the ground cover (Carlisle et al., 1967b: Armson,

19 73) Some ground flora also seem to be predisposed to K accumulation.

An example of this is the ubiquitous broaden fern (Pteridium aquilinum)m),

a fire resistant inhabitant of woods and thickets (Cobb, 1963; Waters,

1903). Totals of 10 to 16 kg/ha of K have been found in bracken cover

in oak forests in England. It contributed 18 31% of the annual K











input into the soil (Carlisle et al., 1967b). In eastern Australia, K

deficient areas of radiata pine failed to display deficiency symptoms

or respond to K fertilizer applications in spots where bracken was

present (Hall and Parnell, 1961).


Summary

Numerous methods of modeling the K cycle in forest ecosystems

have been attempted and in general all have followed the concept of the

biological and geochemical cycling systems previously described

(Duvigneaud and Denaeyer-De Smet, 1970; Jordon et al., 1972). By

examining the uptake and distribution of K in the system, inputs and

outputs from the system, and ascertaining the adequacy of the system to

sustain optimum growth, a logical outline of K flow can be charted as

shown in Fig. 1 (Ovington, 1965). The addition of fertilizer as a single

input into a natural system is showJn in Fig. 2 in a systems model

developed by Curlin (1970). Both show the interdependency of all the

components of the biosystem in maintaining adequate nutrition.
N 0TE


Annual report of Dept. of Forestry, 1.971.-1972. Queensland,
Australia.





22














Rainfall input


10 kg 30-40 kg 30-40 kcg

0BOLE BRANCH LEAVES
P


rl rl Q~cc~~ 150 n1 0



7 ~ lecdecomp0




a, lo E s Leachin loss un
Fiuesbsd nth -ycei 7yer-ol treana mut/a


Fig. 1. Potassium cycle in Scots pine.





Transfer from one compartment to another indicated by arrows.


Fig. 2. A systems model to mineral cycling.

















MATERIALS AND METHODS


Experimental Site


Location and Description of Stand

The 13-year-old slash pine plantation used for the experiment

was located in the Austin Cary Memorial Forest. The forest is owned

and controlled by the University of Florida as a teaching and research

laboratory and is situated approximately 15 km northeast of

Gainesville on State Highway 24 in Alachua County, Florida.

Local history indicates that the area originally supported a

longleaf pine (Pinus palustris) forest and may have undergone a period

of naval stores production prior to acquisition by the University.

Trees were harvested in 1959 and prior to replanting the area

was burned and bedded. The 1 0 slash pine seedlings originated from

a single, open-pollinated seed source and were hand planted at a spac-

ing of 1.5 x 3 m in December, 1960.

Measurements made in April, 1973 gave a site quality (age 25)

of 65 for the stand (Barnes, 1955). The 13-year-old stand had a mean

height of 11.1 m and mean diameter at breast height (dbh) of 12.3 cm.

Stand density was 1660 trees/ha with diameter class distribution given

on the following page.











Diameter class %

6.25 cm 5
8.75 cm 8
11.25 cm 30
13.75 cm 34
16,.25 cm 20
18.75 cm 3

Basal area of thie stand was 20.0 m2 with an estimated crown

cover of 80 ~t-o ~85%. A litter layer of only 1 to 2 em was developed.

The ground cover consisted mainly of saw palmetto (Serenoa

re~pen) and bracken fern (Pteridium aquilinum) with scattered wire

grass (Aristida stricta) and blackberry (Rubus occidentalis).


Soil

The soil of the area was imperfectly drained and classified as

a sandy, siliceous, hyperthermic family of Aeric Haplaquods. It had

been mapped as a Leon very fine sand, but is now classified as a Myakka

soil (Miyakka is the hyperthermic taxadjunct of the L~eon soil and occurs

to the south of a line drawn between Perry and Jacksonville). The soil

had a 1 to 2 cm thick organic layer (01) over an inorganic dark colored

surface horizon (Al1) of 10 cm (Table 25). The A2 was between 45 and 75

em thick and was light gray in color. The B2h horizon was irregular in

depth and varied from a well developed spodic horizon to a weakly

developed staining with no evidence of induration. The C horizon was

light colored with occasional mottles and extended approximately 1.5 to

2 m where a D1 horizon of clay loam was uniformly present.

The surface soil was very fine sand with silt plus clay frac-

tions of less than 5 percent. Acid conditions prevailed with low CEC,

low organic matter, and low available nutrients (Table 25). The A2 was

very low in organic matter and lower in CEC and available nutrients than











the surface horizon. The spodic horizon had greater organic matter

than the surface horizon with CEC and available nutrients similar to

the surface when it was present in a well developed state.


Climatic Data

Mlean annual temperature for A~lachua County is 21.1 C with

average temperature for the months of December, January, and February

falling below 15 C (U.S. Weather Bureau, 1970). May through September

temperatures were between 25 to 30 C giving the area a broad sub-

tropical to warm temperate classification. MIean annual soil temperature

was 23 C and the mean annual rainfall was 133 cm. Rainfall was

seasonal with nearly half falling during the summer months of June

through September in severe, convection caused, thundershowers. The

dry season extends from November to January with monthly averages of

less than 7.5 cm with a second dry period often occuning from the last

of April to mid-June.

The rainfall data from 1973 to 1974 from Austin Cary Memorial

Forest are given in Fig. 3. The rain gauge was located approximately

2 km from the experimental site (Kaufman, C.M~., personal communication)

Average depths to ground water measured in water table wells

placed in the experiment are shown for selected dates in Fig. 1. Water

table in the experimental area fluctuated from a low of 2 meters during

the dry season to at or above the surface during the wet season.



E1xperimental Method


Experimental Design

A randomized block design with three blocks of five treatments











each was established in the plantation. Blocking was done because of

a suspected topographic and drainage gradient existing across the area.

Each plot consisted of a 0.04 ha gross plot that received fertilization.

A 0.02 ha net measurement plot consisting of 4 tree rows of 16.6 m

length was used for measurements and sampling. Thle treatments applied

were:

KO No fertilizer

KO+ 0 kg/ha K + 40 kg/ha N and 45 kg/ha P

K48+ 48 kg/ha K; + 40 kg/ha N and 45 kg/ha P

K96+ 96 kg/ha K + 40 kg/ha N and 45 kg/ha P

Kl92+ 192 kg/ha K + 40 kg/ha N and 45 kg/ha P

The K treatments were applied as granular fertilizer-grade KC1

with the N and P supplied as fertilizer-grade diammonium phosphate (DAP)

applied at a rate of 224 kg/ha. Application was with a hand carried

cyclone-type spreader calibrated to deliver approximately 10 kg/ha. The

fertilizer materials were then applied by applications in alternate

directions across the gross plot until the fertilizer was expended.

Fertilizer was applied May 2 and 3, 1973.


Sampling Methods

Sampling of foliage, stem flow, through~fall, rainfall, litter,

soil water, ground water, and soil was carried out preceding and follow-

ing fertilizer treatments. Intensive sampling was done over the first

growing season with less rigorous sampling over the second growing

season.

Foliage was collected from 8 to 10 trees in each plot for each

sampling date in the 1973 growing season. Samples were clipped from the











south side, mid-crown position of randomly chosen trees, using pruning

shears on an extension pole. Even distribution between first and

second order branch sampling was attempted, taking care not to deplete

the crown through continuous sampling. After sampling, the shoots were

divided into old foliage (pre-1972 growth), current foliage (1972

growth), and flushes as they became large enough to sample (1973 growth)

Buds and stems associated with the current and flush growth were also

collected for analysis. Collection dates for 1973 were April 24, May

13, May 18, June 4, July 9, August 19, September 13, and November 14.

Stem flow was collected from a tree randomly selected from the

11..25 or 13.75 cm diameter class of each plot. The stem-flow collector

consisted of an aluminum foil collar cemented to the tree stem with

plastic roofing cement. It was placed 1 m above ground level and

positioned to divert the stem flow to a funnel attached to the side of

the tree with an aluminum nail. The funnel was attached to a plastic

tube carrying the stem flow to a covered 36-liter plastic container.

Throughfall and rainfall were collected in one-liter containers

placed on stakes 1 m above ground level. The area of the catchment was

105 em2 and it was fitted with a plastic dise that allowed rainfall to

enter but minimized evaporation. Nylon netting covering the container

prevented entry of litter, insects, and animals. One th~roughfall

container was placed in each plot within 2 3 m of the stemflow catch-

ment tree for the plot. Four open areas adjacent to the plantation

served as locations for the rainfall catchment. Stemflow, throughfall,

and rainfall collections were taken on the basis of rainfall amounts and

frequency. During the first month collections were made after every

rainfall. Thereafter, collections were made approximately monthly.










Literfll collected in 0.97 m2 trays placed on the ground.

They were constructed of 2.5 x 10 em wooden frames with 0.3 cm2 mesh

galvanized hardware cloth bottoms. A tray was placed at a random posi-

tion between rows within 5 m of the stemflow sample tree in each plot.

The trays were put in place April 24, 1973 and collections were taken

5, 28, 60, 97, 133, 150, 163, 191, 282, and 582 days following fertili-

Zat ion.

Soil water and ground water collectors were placed in random

locations between rows within 5 m of the stemflow sample tree and with-

in 1 m of each other. Soil water was collected from 20 and 40 em depths

in each plot by means of 2.5 em tubes fitted with porous ceramic cups.

Water was extracted from the soil by evacuating the air from the tubes

creating a negative pressure that allowed water to move from the soil,

through- the ceramic tip, into the tube. Sampling of the soil water was

then accomplished by removing the water from the tube with gentle suc-

tion. Evacuation and sampling were accomplished using a hand vacuum

pump fitted with a sample trap. Soil water was sampled 1 day prior to

treatment and 15, 19, 25, 60, 101, and 133 days following fertilization.

Around water wells were dug to 1.8 m with a 10 cm bucket auger.

A plastic cylinder 15 em diameter and 15 cm high was placed around the

hole to prevent surface cave-in of the well. A 15 cm plastic pot was

used as a cover for the well. Ground water depth measurements were taken

for each plot by measuring depth~ to free water with the ground line as a

reference. Sampling was done by suction similar to soil water sampling.

Little caving occurred during the duration of the experiment and was cor-

rected by reaugering the well to remove the slumped soil. Ground water

samples were taken 16 and 6 days before and 15, 25, 28, 60, 101, and 133





days following fertilizer application.

Soil samples were taken with a 2.5 cm diameter soil sampling

tube from 10 to 12 random locations within each plot. Samples were

taken from the 0 to 10 and 10 to 20-cm depths prior to the fertilizer

application. Six days following the treatment 0 to 2.5 and 2.5 to

5-cm depths only were sampled. Nineteen days following treatment 0 to

2.5, 2.5 to 5, 5 to 7.5, 7.5 to 10, and 10 to 20-cm soil depths were

sampled. At 25, 102, and 500 days following treatment, samples were

collected from the same depths as the 19 day sampling with 20 to 40,

and 40 to 60 cm depths taken as well.

Selected ground vegetation consisting of the above ground por-

tions of bracken fern (Pteridium aquilinum) and saw palmetto (Serenoa

repens) was harvested on August 13, 1973. Numerical methods were used

to evaluate the saw palmetto by counting the total number of plants

within the plots. Random samples of palmetto were taken for weight per

plant determination and tissue analysis. Cover measurements were

estimated for palmetto in the field by measuring per plant coverage.

The bracken fern was sampled by harvesting the total number of fronds

in random 1.5 x 3 m quadrants unoccupied by saw palmetto.


Laboratory Analysis

All tissue samples were transported to the laboratory immediate-

ly after harvest, dried to constant weight at 65 C, and ground to pass

a 20 mesh sieve in a stainless steel Wiley M~ill. Appropriate weights

of tissue were dry ashed in a muffle furnace at 450 C to prevent K

volatilization (Jackson, 1958), the ash taken up with 0.1 N HC1,

filtered, and taken to volume for nutrient analysis. Potassium and Na





were determined by flame emission, Ca and Mg by atomic absorption spec-

trophotometry with lanthanum oxide added to suppress interference

(Perkin Elmer Corp., 1971), and P was determined by the ascorbic acid

method (Watanabe and Olsen, 1965).

Water samples were analysed within 1 or 2 days of collection,

using the methods described above for individual elemental analysis.

Conductivity and pH were determined on selected samples using a

Barnstead conductivity bridge and pH meter, respectively.

Soil samples were air dried, sieved to 20 mesh, and extracted

with N NH OAc buffered at pH 4.8. A 10-g sample was extracted with 1:5

soil to extractant ratio in 90 ml Nalgene centrifuge tubes for 30

minutes in a reciprocating shaker. Following shaking, the suspension

was centrifuged and an aliquot of the supernatant solution was taken

for K, Na, Ca, Mg, and P analysis.

Soil pH was determined by pH meter in a 1:5 soil to water

suspension and a 1:5 soil to N KC1 suspension. Organic matter determi-

nation was by a modified Walkley-Black wet digestion method (Jackson,

1958) and particle size distribution by the hydrometer meter. Bulk

density was determined by weighing soil cores. Available but non-

exchangeable K; was determined by boiling soil in N HNO3 for 10 minutes

at a ratio of 1:10 soil to acid.

Total analysis was done by digesting 100 mesh soil samples with

HF in platinum crucibles (Jackson, 1958). The final HC1 digest was

analyzed for K, Na, Ca, and Mg.


Growth Data

Initial height and diameter measurements of each tree in all

plots were taken in April of 1973 prior to height growth initiation for











the year. Final measurements were taken in October of 1974 after

height growth for the season had terminated. Heights were determined

by Haga hypsometer and dbh was determined by steel diameter tape.

Total inner bark tree volumes were calculated using a volume

formula modified for slash pine (CRIFF Progress Report, 1973-74)1


Vol in m3 = .000030(dbh)2(ht) + .00207

where dbh is in em and height is in m.

Needle lengths for the first flush of 1973 were determined at

the time of foliage sampling. Average needle lengths were taken from

the mid-point of the flush from 8 to 10 trees. Crown cover was

estimated from field observations.


Whole Tree Hlarvest

One tree from each plot in block I was felled for total above

ground biomass analysis (Newbold, 1967). These trees were selected on

the basis of random diameter class assignment stratified according to

total diameter class distribution for each plot and a random selection

of a single tree belonging to that class interval within the plot.

Total 1974 foliage, total 1973 and earlier foliage, total live

branches, dead branches, stem wood, and stem bark were determined for

each tree on a dry weight basis and compared with standard biomass

formulae found in the literature (Miead, 1971; Nemeth, 1973; MlcKee and

Shoulders, 1974). Nutrient concentration was determined on these

tissues and compared with the foliage nutrient concentrations of the

prior year as well as with published values for use in estimating

nutrient content.











Volumes were determined on the felled stems according to

Smalian's combined formula (Strickland, personal communication).


Statistical Treatment of Data

Standard methods of statistical analysis were used in the treat-

ment of data (Steele and Torrie, 1960; Snedecor anid Cochran, 1967) with

the bulk of the analysis run with the IBM 360-165 computer using the

Statistical Analysis System (Barr and Goodnight, 1972) of computation.

Details of the individual statistical analyses are given where

appropriate.




NOTE

1CRIFF Progress Report (unpublished), 1973-1974. Soil Scienice

Department, University of Florida, Gainesvil~le, Florida. VolIume

formula modified from: Bailey, R.L., and J.L. Clutter, 1970. Vo lume

tables for old-field loblolly pine plantations in the Georgia piedmont

Ga. Research Council Report 22.
















RESULTS AND DISCUSSION


Precipitatio Inputs ino the Syse

While fertilizer applications may have a large, but relatively

short-term impact on the slash pine ecosystem, the effect of inputs

into the system from atmospheric sources is continuous. Both wet and

dry depositions were collected with no attempt to separate the two in

this experiment. During the first month, collections were taken after

every rainfall. Subsequent samples were collected every month or when

approximately one liter of rainfall had accumulated in the collector,

whichever came first. Amounts of rainfall by collection date are

recorded in Table 2. Rainfall was determined by measuring the volume

collect-ed, with each 1.00 ml collected equivalent to 0.95cm of rainfall.

During the first month of the experiment rain fell on six sepa-

rate occasions for a total of 15 cm. This was followed by frequent

short storms during June and into July (Fig. 3). A two-week rainless

period in mid-July was followed by frequent rainfall through early

August. Rainfall from then till the end of the year was relatively in-

frequent. A total of 85 cm of rainfall was collected at the experiment-

al site during the 1973 experimental period. Rainfall records from a

recording rain gauge located at another site in the Austin Cary Forest

indicated 100 em of rainfall for the same period of time.

Less rigorous sampling was done during 1974, with samples taken

every two months. A total of 66 cm was collected during the 1974 sampl-

ing period from Jan. 1 to Sept. 24, 1974. The nearby recording rain



















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gauge recorded 101 cm of rainfall for the period.

Rainfall nutrient concentrations for the 17-month duration

averaged 0.16, 0.74, 0.46, 0.13, and 0.02 ppm, respectively, for K, Na,

Ca, Mig, and P (Table 2). Annual contributions of these elements were

1..6, 7.2, 4.6, 1.3, and 0.2 kg/ha, respectively.

The total annual input of nutrients into the system agrees well

with data reported in the southeastern United States (Wells, 1974) and

other areas of the world (Table 1).

Growth Response in the Fertilized Plantation



Volume Increment Response to Treatment

No volume increment increases due to treatment were detected in

the experiment (Table 3) over the 17-month experimental period. To tal

volume increased from an average of 0.0578 m3/tree to 0.0681 m3, with an

average increment of 0.0091 m3 per tree. The total stand volume at the

beginning of the experiment was 96.8 m3 compared to 111.3 at the con-

clusion, or an increase of only 14.5 m3 for the 17 month period (Table 4).

Neither basal area, height, dbb, nor calculated wJeight of foliage

exhibited a response to K treatment. WJhile this site was not identified

as a K responsive site, it did have soil characteristics of low exchange-

able K; and low total K that suggested K might be a limiting factor for

tree growth. Applications of 90 kg/ha to similar soils in the south-

eastern United States on poorly and very poorly drained sites have been

shown to increase volumes by as much as 46% compared to the average

volume of plots receiving N and P (Pritchett,W.L. ,personal communications). In

the northeastern United States it has been found that 2 to 3 years must

elapse after treatment for significant increases in diameter and height












TABLE 3. Analysis of variance of volume increment response.




Source df ms F

Treatment (A) 4 0.0278295 0.687 ns

Block (B) 2 0.1078477 2.663 ns





Error 491 0.0405017


ns indicates no significance.

















O 0





O O~



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00




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to become apparent (Gagnon, 1965). Additional. measurements must be taken

at a later date to determine if this was the case in the present study.

Volume increments found were somewhat less than the 10 to 15

m3/yr- reported elsewhere for slash pine grown under similar conditions

(Mlalac, 1968; Nemeth, 1973; and Barnes, 1955). The relatively small

increment may be due in part to the failure of th~e final measurement to

reflect the maximum diameter increase for the 1974 growing season, but

must also reflect a poor site condition that is not related to K nutri-

tion .


Needle Lnth

While needle length alone cannot define a nutrient response it

was anticipated that the reported short length of needles due to K

deficiency (Heiberg and White, 1951; Raupach andi Clarke, 1972) might be

corrected with K treatment.

Needle measurements taken throughout the 1973 growing season on

the first flush, mid-crown growth showed no significant differences in

needle length for the period during which elongation was taking place

(Table 5). While no increase in needle length due to K fertilization

occurred, an increase due to treatment with N and P, unrelated to K

treatment was observed at the final measurement. Longer needle length

has been observed in fertilized trees for up to 15 years following fer-

tilization (Gooding, 1970).


Effect of Fertilization on K and Othier
Nutrient Contents in Tissue


K Concentration of Tissue as Influenced by Time and Fertilization

Foliage Kt concentrations are given in Table 27. The dlesi~gnation














TABLE 5. Variation of flush needle length with time (age) and treat-
ment during the 1973 growing season. (9/14/73) represents
date of maximum needle elongation)



D~atea
Treamen 5 /18/73 6/5/73 7 /9/i73 9/14/73
- - - - - - - - - c m - - - - - - -


aColumn eniefoledbth same letter as a control do not differ
significantly (P = 5) ro he control as determined by Dunnett's
method of comparing several treatment means with a control (Dunnett,
1955).

S(L) is the estimated standard error of a difference between two
means =2eromansquareN where N = 24 observations per mean.


5.15 a


7.42 a

7.46 a

6.84 a

6.79 a

7.15 a

0.457


13.22 a

13.82 a

14.98 a

13.89 a

14.12 a

0.675


20.08 a

22.04 b

22.33 b

22.45 b

22.37 b

0.756


KO+ 4.39 a


K48+

K96+

Kl92+

S(L~b


4.16 a

3.99 a

5.07 a

0.589











"old needles" represents those needles older than one year at the start

of the experiment (those needles initiated during 1971). "Current

needles" were the needles initiated during 1972. First and second flush

needles and the bud and stemn of those flushes were those initiated

during the 1973 experimental period and were sampled as they became

available.

Similar patterns of K concentrations were observed for all treat-

ments in the various tissues examined (Fig. 4, 5, 6, 7, and 8) with the

old and current needles showing a significant but relatively small

variation in K concentration during the sampling period (Table 6). The

flush samples all showed relatively large differences in K concentration

associated with time of sampling and treatment.

Means of tissue concentration by treatment, regardless of sampl-

ing date, were compared by Dunnett's test for significant differences

between treatment means and a control (Dunnett, 1955), and by linear

regression (Table 7). Trees receiving no K had lower K concentration in

old needles than those receiving the highest rate of K. Current needles

of trees receiving no K had lower K concentrations than trees receiving

K,with the highest rate of K application giving the highest K concentra-

tion in the current needles. The first and second flush needles and the

first flush bud and stem tissue followed the same pattern of differences

in K concentration as the current needles. In all tissue tested, the

increase in K concentration was linearly related to increasing rates of

K applied when adjustment for date of sampling was made. Mul~tiplee

regression equations for the various tissue components are presented in

Table 28.

The application of N and P did not affect the K concentrations


















































E E








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indicates no significance.


indicates significance at P =


indicates significance at P =


__ ______~I__ ~ ___


49





TABLE 6~. Summary of tests of significance for K concentration of tissue
by type of tissue, treatment, and date of sampling.


AXT

*k

**

**


Type of tissue

Old needles


Current needles


1st flush needles


1st flush bud and stem

2nd flush needles


2nd flush bud and stem


Treatment (A)







k

**


Time (T)

AA



**


**~ ns


**ns


ns










50







*4c -# + -i
4' M -lc C


000000







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000000 ci
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o' d o d d 3 9
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bDI I O a,
k +I 1n tr U) ca U t


rd I : 0 0 0 0 0 0V

0+ a to a a




+: I N I tr tr as
8 000000 ct E3


k~~~ III I ,lr
C,~~* t> 4Sla




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a,~~~~ *H I ( I
F:t ed~
d rl HI I


0 0 0 0O 0 *H *H

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o~U H N <0 I a rl bl











in any of the tissue studied.

Treatment means were also compared by date of sampling regard-

less of treatment (Table 8A). The early dates of sampling showed

relatively little effect of treatment on K concentration. By 32 days

after fertilizer application, only the highest K rate had increased

the mean K concentration. Two months after treatment a linear response

of K concentration with increasing rates of K application was found.

The linear trend continued to be significant for thle duration of the

sampling period (Table SA).

Mean R concentration of the various tissues on a given date,

regardless of treatment, in old and current needles did not differ

from one another until well into the growing season, at which time the

mean concentration of the old needles was reduced from its early season

level (Table 8B). The current tissue K; concentration remained

relatively constant throughout the growing season.

The first flush bud and stem was sampled prior to emergence of

the needles, before fertilizer treatments. At two weeks following

treatment, the needles and bud and stem from the first flush differed

in K concentration from that of the first sampling. The K concentra-

tion in the buds and stems showed rapid reduction and the needles in-

creased in K concentration and then decreased linearly. The second

flush needles showed a similar pattern as the first flush but the bud

and stem did not show a reduction of K concentration.

The pattern of K concentration over the sampling period

indicated greater K concentrations in the first flush growth and less

fluctuation in K concentration throughout the growing season than

previously reported (Mead and Pritchett, 1974). The previous year's





00000000


ddddd~~aCOOdd


00000000









0000















dddd9-~-odoo








0000000





0~0000000 \ Dl


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00000000




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000000


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UII cn

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dddd N C



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flush (or current needles) ranged from 0.20 to 0.30% K in the no and low

K rate treatments and increased to a range of from 0.28 to 0.39% with

the highest K application level. The lowest K concentrations generally

occurred at the end of the season and even then differences due to K

application rates existed.

With no K applied, the K concentration inz slash pine in the

study was considerably lower than many pines growing in known K defi-

cient sites. The highest rate of K application in this experiment

elevated the foliar K from the lower range of K concentration to a

middle range for slash pine.


Na, Ca, Mg, and P Concentration of Tissue as Influenced
by Time and Fertilization

Concentrations of Na, Ca, Mg, and P were little affected by

fertilizer treatment during the sampling period with significant dif-

ferences in concentrations only occurring among the various types of

tissue. A summary of these effects is given by element in Table 9.

Average concentrations of Na in foliage were generally below

0.10% (Table 10) with the old needles having larger concentrations than

the current or flush tissue (Table 29). Only traces of Na have been

reported in slash pine foliage (Young, 1948).

Older tissue also accumulated higher concentrations of Ca early

in the growing season (Table 10) and appeared to decrease in concentra-

tion as the flush bud and stem increased in Ca late in the growing

season (Table 30). The first flush needles had somewhat higher Ca con-

centrations than the second flush needles and they both appeared to stay

relatively constant during the season. Calcium concentrations were

comparable to those previously reported for slash pine but did not show




































~__~_~~I~ ____


TABLE 9. Summary of tests of significance for Na, Ca, Mg, and P
concentrations of tissue by type of tissue and treatment
effect.


Treatment (A) Tissue AXB

ns ** ns


ns ** ns

ns **ns

ns ** ns


concentration

concentration


concentration

concentration


indicates no significance

indicates significance at P =

indicates significance at P =



























































_~_~~___


TABLE 10. Average Na, Ca, Mg, and P concentrations in slash pine
tissue.


Treatment
Nutrient __j gue components r____KOf_ KO KO+ 48 K6+ Kl.92+


Na Old needles 0.09 0.09 0.09 0.11 0.10
Current needles 0.05 0.05 0.05 0.05 0.05
1st flush bud and stem 0.04 0.03 0.02 0.02 0.03
1st flush needles 0.03 0.03 0.03 0.03 0.03
2nd flush bud and stem 0.01 0.02 0.02 0.02 0.01
2nd flush needles 0.02 0.02 0.02 0.02 0.02

Ca Old needles 0.24 0.27 0.27 0.26 0.25
Current needles 0.23 0.24 0.24 0.22 0.23
1st flush bud and stem 0.10 0.12 0.13 0.12 0.12
1st flush needles 0.19 0.19 0.20 0.19 0.19
2nd flush bud and stem 0.06 0.07 0.09 0.08 0.09
2nd flush needles 0.12 0.16 0.15 0.14 0.15

Mg 01d needles 0.09 0.10 0.10 0.10 0.09
Current needles 0.12 0.12 0.12 0.12 0.12
1st flush bud and stem 0.12 0.13 0.13 0.14 0.13
Ist flush needles 0.12 0.13 0.13 0.13 0.12
2nd flush bud and stem 0.12 0.12 0.13 0.13 0.12
2nd flush needles 0.14 0.14 0.16 0.15 0.15

P Old needles 0.09 0.09 0.09 0.09 0.09
Current needles 0.08 0.09 0.09 0.09 0.09
1st flush bud and stem 0.1 0.12 0.11 0.11 0.11
1st flush needles 0.08 0.08 0.10 0.09 0.09
2nd flush bud and stem 0.10 0.08 0.10 0.10 0.11
2nd flush needles 0.10 0.10 0.12 0.11 0.11





much increase in needle Ca concentrations among dates (MIead and Pritchett,

1974).

Little variation occurred in the Mg concentration with the excep-

tion of the lower concentrations in the old needles (Tables 10 and 31).

Needle concentration of Mg has been found to vary dramatically with loca-

tion within the concentration occasionally higher in the new flush than in

the previous year's growth (current) and ranging from 0.07 to 0.14% in

the needles with no consistent increasing or decreasing trend obsery-

able.

Phosphorus was also unaffected by treatment, even though DAP

had been applied at 45 kg P/ha. Type of tissue was only a minor source

of variation (Tables 10 and 32).

Phosphorus concentrations observed were consistent with

reported values in tissue and showed little variation with time during

the growing season or with type of tissue (Mead, 1971).


Leachin of Nutrients from the Trees


Throughfall Nutrient Concentrations

Concentration of K in thle throughfall increased from 0.45 ppm

with no K application to 0.67 ppm with 192 kg K/ha (Table 33). Thre

annual contribution of K by the throughfall, increased linearly from 3.7

to 5.7 kg/ha (Table 11) with a regression equation of kg K/ha =

3.53 +- 0.01.1 kg K/ha applied. When the 1.6 kg K/ha/yr in rainfall was

subtracted from this quantity a net of 2.1 kg K/ha was found to have

been added as it passed through the tree crowns of the trees receiving

no K< and 4.1 kg K/ha in the trees receiving 192 kg K/ha. Whether this

was leached from the foliage or dust is not readily known.

















Trea tmentab
Nutrient KO KO+ R;48+ K96+ Kl92+ S (L) N
----------------------kg/ha-----------------

K( 3.85 / 3.87 3.68 4.42 5.72 0.72 3

Na 8.02 7.80 7.46 8.38 9.53 0.80 3

Ca 8.49 6.60 4.88 6.51 7.26 1.15 3

Mlg 2.44 2.59 1.85 2.27 2.78 0.51 3

P 0.10 0.10 0.12 0.15 0.10 0.14 3




Row means connected by the same line as the control (KO0+) do not differ
significantly from the control (P = 5%) as determined by Dunnett's test.
RO0 and KO+ do not differ significantly when compared with a Student's
t-test.

See footnote b, Table 7.


TAB~LE 11. Annual nutrient contents of throughfall.





Sodium concentrations in the throughfall were not much greater

than the rainfall values and gave no evidence of fertilizer effect

(Table 11). The average annual Na contribution in throughfall was 8.2

kg/ha compared to 7.2 kg/ha in rainfall. Values of Ca, Mlg, and P in

the throughfall showed no treatment effect (Tables 11 and 34). Quanti-

ties in the throughfall were 6.7 kg Ca/ha, 2.4 kg Mig/ha, and 0.11

kg P/ha annually. When the rainfall contribution was subtracted, the

net throughfall contributions were 2.2 kg Ca/ha and 1.1 kg Mg/ha.

Phosphorus in the throughfall was lower than the rainfall P content,

0.11 kg/ha and 0.20 kg/ha, respectively, giving a net uptake in the

crown rather than a loss, suggesting direct foliar absorption of

nutrients (Ovington, 1960).

In the southeastern United States, 10blolly pine throughfall

and stemfl~ow were combined for annual contributions of 12.3 kg K/ha,

6.0 kg Ca/ha, 2.0 kg Mg/ha, and 0.5 kg P/ha (Wells and Jorgensen, 1974).

Other than the higher K and P contribution, the loblolly pine values

agreed with those found here for throughfall only. Radiata pine had

larger amounts of K, Mg, and P, but smaller amounts of Ca than found in

this study (Attiwill, 1966; Will, 1955; IWill, 1968). Other studies

have shown much greater nutrient concentrations in throughfall. Annual

values as high as 35 kg K/ha, 35 kg Na/ha, 30 kg Ca/ha, 10 kg Mg/ha,

and 0.5 to 1.0 kg P/ha have been reported (Madgwick and Ovington, 1959;

O'Hare, 1967; Reiner, 1972; Tamm, 1951).


Stemflow Losses from Trees

Stemflow losses of nutrients were small with no apparent treat-

ment effect (Table 12). Annual losses of 0.21 kg K/ha, 0.38 kg Na/ha,


















Treatment
Componn O K+ 4+K6 K9+Aeag (L
------------------ liter/tree -------------------

Stemflow collected 187 155 173 203 169 177 58 3
- - - - - - - - - c m - - - - - -


TABLE 12. Annual nutrient loss from trees by stemflow.


3.0 2.5 2.8 3.3 2.5 2.8 0.92 3
--------------------- kg/ha ---------------------

0.21 0.18 0.22 0.23 0.22 0.21 0.05 3

0.41 0.34 0.34 0.47 0.34 0.38 0.11 3

0.42 0.41 0.49 0.47 0.42 0.44 0.08 3

0.10 0.11 0.12 0.13 0.11 0.11 0.05 3

-----------------ppm ----------------------

0.67 0.72 0.76 0.68 0.81 0.73

1.36 1.37 1..38 1.36 1.25 1.35

1.38 1.64 1.71 1.37 1.59 1.53

0.40 0.42 0.43 0.38 0.42 0.42


Stemflow



K content

Na content

Ca content


M~g content




K concentration

No concentration

Ca concentration


Mlg concentration


aSee footnote b Table 7.











0.44 kg Ca/ha, and 0.11 kg Mg/ha were found. Only traces of P could

sometimes be found in the stemflow. These values represented less than

10% of the rainfall input. Nutrient contents of the stemflow in other

studies were found to represent only 5% of the throughfall contribution

(Wells and Jorgensen, 1973). While calculated on a per ha basis, stem-

flow may more directly affect the area immediately surrounding the tree

with its higher nutrient content.


Throughfall and Stemflow Q~uality and Quantity as
Affc~ted by Amounts~ of Rainfall

The origin of the nutrients in throughfall is open to question,

although the water solubility of the nutrients in plant tissue is well

documented (Cassiday, 1966). In an attempt to examine throughfall leach-

ing more closely, regression analysis of throughfall. nutrient concentra-

tion against quantity of throughfall for the various elements was

performed (Table 13). The equations for K did not differ greatly with K

treatment but did show a low negative linear relationship with quantity

of throughfall. The nutrient concentration extrapolated to 0 volume

indicated an initial throughfall concentration of 1 ppm K as compared to

an overall average of only 0.5 ppm; suggesting that the initial rate of

removal is greater than the overall rate of removal. Sodium behaved

similarly, with an initial concentration 1.42 ppm as compared to a 1 ppm

overall average. This was not the case with Ca and Mg, as both initial

and overall average concentrations averaged 0.9 and 0.3 ppm, respectively.

While dust accumulation on foliage may be a source of throughfall

nutrients (Nihlajard, 1970; Schlisinger and Reiner 1974) the leaching

of nutrients from the live foliage cannot be discounted.

When rainfall and throughfall volumes were compared by regression





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(Fig. 9) a high correlation was found. Differences between rainfall

and throughfall by collection are shown in Fig. 10. Stemflow was also

compared to rainfall by regression (Fig. 9). On an annual basis,

throughfall was 85% of the rainfall and stemflow was 3% of the rainfall

on a total area basis. By difference, crown retention was found to

account for 12% of rainfall.

Approximately 100 rainfall events occurred during the experi-

mental period during which 151 cm of rain fell. Of this, 88% was ac-

counted for by throughfall and stemflow. The remaining 12% or 18 cm of

rainfall was divided between the individual rainfall events, giving ap-

proximately 0.18 cm of rainfall as a measure of crown retention.

While the plantation under study had not completed crown

closure, the results of the stemnflow and throughfall compared with

results found elsewhere (Czarnowski and 01szewski, 1968; Nye, 1961;

Stanhiill, 1970; Smith, 1972; Voigt, 1960).


L~itterfall


Estimates of Annual Litterfall

While needle fall occurred throughout the year, a large propor-

tion was found in the winter (Table 35).

Litter weight averaged 3.8 t/ha/yr for the needle portion and

0.4 t/ha/yr (Table 36) for the "other" (branch, bark, cone and duff)

portion (Table 37) and was not affected by fertilizer treatment. This

compares with 3 to 5 t/ha/yr of needle production and 0.3 to 1.4 t/ha/yr

branchfall found in loblolly pine (Wells, 1974) and 4 t/ha/yr for

Caribbean pine (P. caribaea) (Bray and Gorham, 1964).





Effect of Fertilization on Litter Nutrient Concentration

No differences were found in nutrient concentration either in

the needle litter or in the other litter (Table 14) with the exception

of K; treatment at 192 kg K/ha level. Annual nutrient returns to thle

forest floor through litterfall were 1.5 kg K/ha for the 0 K applied,

increasing linearly with K applications to 3.5 kg K/ha for the highest

K treatment. Other elements returned to the forest floor annually were

1.8 kg Na/ha, 12.1 kg Ca/ha, 3.5 kg Mg/ha, and 1.5 kg P/ha. Rainfall

volumes did not affect the litter nutrient composition as determined by

comparing the nutrient concentration at different dates with the amount

of rainfall that occurred between litter collection dates.

The annual returns of litter fall were similar to those of a

21 m2 basal area stand of thinned loblolly pine in thle southeastern

United States that had only 2.2 t/ha/yr total litter fall (W~ells, 1974)

indicating a lower concentration of nutrients in the slash pine litter

in this study.

Residence Time of K and Other Nutrients in the Forest Floor


Samples taken below and adjacent to the 15 litter collection

trays were examined to estimate the residence time of litter and

nutrient losses over time. Because there was no weight response to

treatment, the average litter and floor weights of all plots was used.

An average of 5.4 t/ha of needle fall occurred over the 17-

month experimental period. Under the litter trays there had been a 17-

month period of decomposition with no new additions, resulting in a

residual of 5.9 t/ha of litter (Table 15A). The undisturbed forest

floor was found to have an average of 12.2 t/ha as compared to only













TABLE 14. Annual nutrient content of litter from slash pine.



Litter Treatment3
Nutrent _comppypg: RO KO+ K48+ K96+ Kl92+ S(L) N r
---------------- kg/ha -------------


Weigh t Needles 3805 3634 3748 3836 3996
Other 384 170 39 3 501 655

K Needles 1.7 1.5 2.0 2.2 3.5
Other 0.1 0.1 0.1 0.1 0.1


532 3 0.226 ns
195 3 0.589 *


0.34 3
0.063


0.880 **


Na Needles 1.7 1.7 1.6 1.9 2.0
Other 0.0 0.0 0.1 0.1 0.1





Mlg Needles 3.5 3.4 3.2 3.7 3.7
Other 0.1 0.1 0.1 0.3 0.1

P' Needles 1.2 1.7 1.6 1.6 1.5
Other 0.0 0.0 0.0 0.1 0.1


0.293
0.05 3





0.97 3
0.20 3

0.30 3
0.09 3


aSee footnotes a, b, and c Table 7. K;O and KO+ do not differ significantly
when compared with a Student's t-test. Means connected by thie same line
as the control (KO+) do not differ significantly from the control
(P = 5%) as determined by Dunnett's test.





TABLE 1.5. Quantities of litter, forest floor, and nutrient at
conclusion of experiment.





A. Weight relations


Forest floor
Litter Adjacent to
Treatment Col~lector Under collector collector
------------------- ,kgfha/17 mo ----------------

K0 5.4 6.5 12.0

KO+ 5.1 5.6 11.4

K48+ 5.3 6.9 13.0

K96+ 5.4 5.2 11.9

Kl92+ 5.7 5.1 12.5

Average 5.4 5.9 12.2

S(L~a 0.75 0.96 1.79

B. Nutrient relationships


Litter nutrient Forest floor nutrient
Nutrient concentration concentration



K 0.057 0.046

Na 0.046 0.015

Ca 0.320 0.380

Mg 0.091 0.077

P 0.040 0.036











11.3 t/ha for litter fall collected plus the residual floor under the

trays, although this difference was not significant.

When the nutrient concentration of the forest floor was compared

to the average litter fall nutrient concentration, a 20% reduction of K

and a 67% reduction of Na was found. Calcium, Mig, and P were found to

increase 19%, decrease 15%, and decrease 10%, respectively, from the

litter fall to the forest floor (Table 158).

The forest floor measurements show results comparable to those

of other areas of the southeastern United States of similar aged

loblolly pine (Switzer and Nelson, 1972; Metz, Wells, and Kormanik,

1970). Accumulation of Ca with losses of Na, Mlg, and P from the floor

was expected due to the insolubility of Ca in the tissue and the solubil-

ity of the other nutrients. The small magnitude of the K loss may have

significant implications in the ability of slash pine to maintain

adequate growth with small amounts of soil K.


Nutrient Status of Soil and Soil Water Following
Fertilization

Changes in Soil K with Depth and Time


Soil K concentration increased 6 to 22 times with increasing K

treatment as early as 6 days following fertilization (Fig. 11, May 9,

1973). Only 0.6 cm of rainfall had occurred, but time was apparently

sufficient to move fertilizer K to depths greater than 5 cm in the

soils receiving 96 and 192 kg K/ha. Recoveries of K< from soil were cal-

culated by summing the extractable soil K for the profile depth, subtract-

ing the extractable K found in the treatment receiving no K, and dividing

the excess K by the application rate. At the first sampling after











treatment, recoveries of 108, 45, and 66% of applied K were found in

plots receiving 48, 96, and 192 kg K/ha, respectively. In the 96 and

192 kg K/ha treatments, sampling depth appeared to be insufficient to

recover larger amounts of applied K.

By the 19th day after sampling the influence of K application

extended to a depth greater than 20 cm (Fig. 11, Many 22, 1973) with

less than 5 cm of rainfall since fertilization. Recoveries from soil

were 59, 69, and 57% for treatments receiving 48, 96, and 192 kg K/ha,

respect lively. Deeper sampling of the soil on the 26th day after

fertilization showed little added recovery of K but did show a redis-

tribution of K down the soil profile (Fig. 11, May 29, 1973). Concen-

tration of K in the 40-60 cm depth ranged from 1 to 7 ppm only (Table

26).

After 100 days, treatment effects were still present and 34,

25, and 29% of the applied K was found (Fig. 11, August 13, 1973).

By the conclusion of the experiment, 15, 13, and 7% of the 48,

96, and 192 kg K/ha added were recovered, respectively (Fig. 11,

September 24, 1974).

A summary of the analysis of variance tests of significance for

soil K and other nutrients during 1973 are given in Table 16.

Recoveries in the soil calculated only on, the soil extractable

basis indicated that K was not being removed rapidly from the soil by

leaching as elevated K concentration front moving down the soil with

time was not observed. Ground water K concentration did show increased

K concentrations and may account for some loss. Plant uptake may

account for some of the unrecoverable K in the soil (Bengtson and Voight,

1962; Riekei t, 1971; Krause and Wilde, 1960), but insufficient sampling















TABLE 16. Summary of tests of significance for sampling time and
nutrient concentration of soil by treatment and depth.


Date


5/ 9/73


Nutrient

K
Na


Trea~tment (A)



ns
ns
nS




ns
nS
ns
k*

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ns
ns
nS



**
ns
ns
ns


Depth (D)


5/22/73







5/29/73







8/13/73


**


not significant
indicates significant at 5% level
indicates significant at 1% level













































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depth, fixation, and microbial uptake (Ewel et al., 1975) must also be

considered.


Changes in Other Nutrients with D~epth and Time

Concentrations of Na, Ca, and Mlg varied with depth and time of

sampling (Table 17), but were not influenced by treatment (Table 16).

Phosphorous concentration in the surface 5 cm of soils receiving DAP

was higher during the first month~ after fertilization than the soil

that received no phosphorous (Table 26).


Soil Water and Ground W~ater Nutrient Concentration

Soil water nutrient concentrations show that K may move more

rapidly into the soil via soil water than soil sampling would indicate,

with relatively high concentrations being detected at 20 and 40 em

depths within 15 days after fertilization (Table 18). There was a

linear response at the 20 em depth but not at the 40 em depth. No

indication of K leaching into the ground water was detected until 60

days following fertilization when there appeared to be a linear increase

of K in the ground water due to K application rates (Table 18).

Average K contents of the unfertilized treatments were similar

to those found in tension lysimeter studies elsewhere in the Austin

Cary forest on similar soils (CRIFF Progress Report, 1973-74), with a

peak concentration in the spring of the year and a decline after the

onset of the rainy season in June. Variation in concentration of

cations in the ground water was high, with coefficients of variation

often reaching 50% and variation of concentration of cations in the soil

water often exceeding 100%.














TABLE 17. Average Na, Ca, Mg, and P concentrations in soil by sample
date and depth.


Na Ca Mlg P

Date Depth (cm) ---------------- ppm --------

4/27/73 0 5 9 75 11 1.8
5 10 10 30 3 1.6

5/ 9/73 0 2.5 11 102 15 19.0
2.5 5 9 72 10 8.9

5/22/73 0 2.5 4 64 10 7.7
2.5 5 4 51 8 5.3
5 7.5 4 45 6 3.9
7.5 10 4 37 5 3.3
10 20 4 23 2 2.9

5/29/73 0 2.5 6 85 13 4.1
2.5 5 5 58 8 3.9
5 7.5 5 56 7 3.7
7.5 10 5 44 5 3.1
10 20 3 34 3 2.8
20 40 4 14 2 1.9
40 60 4 11 2 1.8

8/13/73 0 2.5 8 86 12 2.3
2.5 5 9 63 8 2.0
5 7.5 8 52 7 1.9
7.5 10 8 47 5 2.0
10 20 5 25 4 1.8
20 40 5 13 3 1.8
40 60 5 9 2 2.0


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Estimation of Water Use by the Plantation

Because of the role of K in the water relationships in trees it

was hoped that a close examination of water table depths with treatment

would reveal any differential water use in the plantation. Analysis of

variance of water table depth with treatment was not significant.

While few water use values for slash pine have been reported,

recent work in the Austin Cary Forest (CRIFF Progress Report 1973-74)'

has shown a 40 cm difference in water table depth in Leon fine sand

between an established stand and of 18- to 20-year-old slash and longleaf

pine and a clear cut area in late spring when growth had stabilized. If

an average bulk density of 1.4 g/cm3 and a specific gravity for quartz

sand of 2.65 (Berry and Mason, 1959) was assumed, each cm of ground

water fluctuation would represent 0.47 cm of free water (% pore volume

=100 [1.4 g/cm3 e 2.65 g/cm31)

A water use (transpiration) estimate was made by examining thle

rate at which the water table was lowered in the established stand as

compared to the clear cut area in the previous work. During June 1974

the water table dropped 20 em in 21 days in the clear cut area. In the

established stand, the water was lowered by approximately 31 cm during

the same time. This lowering of the water table depth by a difference

of 0.52 cm/day or 0.24 cm of free water/day may approximate water use by

the 18 to 20-year-old natural stand of slash and long-leaf pine during

this period of active tree growth. While this transpiration rate would

not be expected to continue throughout the year to give 88 cm/yr, this

total may approximate the total evapotranspiration from forests of the

area and compares to rates of 98 cm/yr (Hammond, L.C., personal communi-

cation) found in Florida and 60 cm/yr for temperate forests found by

Stanhill (1970).










Rainfall Influences on Soil Water and Ground Water

The average ground water level in the experimental area over the

duration of sampling as it relates to the amount and frequency of rain-

fall, is shown in Fig. 1. Wh-ile soil water was easily sampled with tube-

type tension lysimeters in the early months of the experiment, the onset

of the dry period in October 1973 caused a rapid lowering of the ground

water level, increased soil water tension, and made it impossible to sam-

ple soil water for the duration of the experiment. Rainfall did not at-

tain a sufficient frequency or quantity to raise the ground water level

until June of 1974. Obviously, soil water and ground water are related

to rainfall in a direct way and the depth to the free water table in the

soil gives an indication of the water content of the soil and its tension.

Estimates of Leaching Loss

An estimate of the leaching loss was calculated from the differ-

ence between water use by the trees and the annual rainfall, using the

ground water K concentration (Table 18). An average of 133 cm/yr of

rainfall and 88 cm/yr water use by the trees resulted in a difference of

45 cm/yr leachate (4,500,000 kg/ha). In the check plots the ground water

averaged 0.7 ppm K. In the plots receiving 192 R/ha the average was 2.2

ppm K. The difference of 1.5 ppm K concentration indicated loss of K

through leaching. Concentrations of K as high as 10 ppm at one time

(Table 18) also indicated substantial K loss from the 192 kg K/ha treat-

ment, but dilution of the ground water by both vertical and lateral flow

made estimates of the exact amount difficult. If dilution was disregard-

ed, the 45 cm/yr water loss at 10 ppm K was equal to 45 kg K/yr.

Fertilizer Effects on Selective Ground Cover Plants

Biomass and NutrientCoen Changes in Saw Palmetto

Saw palmetto (Serenoa repens) is a major ground cover plant in





the experimental plantation. An average of 112 plants per plot wars

found by enumeration procedures (Newbould, 1967). Palmetto biomass

ranged from 2107 to 3621 kg/ha with an average 2532 kg/ha (Table 25).

Average surface area covered with palmetto was 28%.

A linear increase of K concentration with K application

combined with biomass differences increased K from 9.2 kg/ha in the

palmetto receiving no K to 24 kg K in those receiving K. The regres-

sion equation for concentration of K in palmetto was; ppm K =

5476 + 28.7 (kg K/ha applied). Sodium, Ca, and Mg concentration were

found to decrease linearly with increasing K application.

Average contents of other nutrients in palmetto were 5 kg Na/ha,

5 kg Ca/ha, 4.3 kg Mig/ha, and 2.1 kg P/ha.


Si omas s and l Nrien t Con ten t Can7gesLDr in Bracen Fer

In areas not covered with palmetto, bracken fern (Pteridium

aquilium) was a common ground cover plant that initiated new growth in

early spring and dried back with the onset of the dry season in late

September. Biomass ranged from 662 to 1176 kg/ha at mid-season with an

average of 940 kg/ha over all treatments (Table 25).

Both K and P concentrations differed by treatment. Potassium

concentration increased linearly with K application rate; ppm K =

14205 + 56.9 (kg K/ha applied). Fern receiving no K averaged 1.31% K,

the low and middle rates averaged 1.95% K, and the high K; rate averaged

2.46% K. The application of DAP increased the P concentration from

0.18 to 0.34%. Concentration of Na, Ca, and Mig were unaffected by

treatment and averaged 0.03, 0.19, and 0.25%, respectively.

The K content of bracken fern averaged 11.7 kg/ha for the no K


















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treatments, 20 kg/ha for the low and middle K treatments, and 22 kg/ha

for the highest K application rate. Other nutrients were found in much

lower quantities with averages of 0.3 kg Na/ha, 1.7 kg Ca/ha, 2.3 kg

Mlg/ha, and 2.7 kg P/ha.


Biomass and Nutrient Concentration in
the Tree Component


Total T'ree Harvest

Above ground biomass of a representative tree. in each treatment

of block I was taken in November, 1974 following the method outlined by

Newbold (1967). Tree selection was by random selection from a

stratified diameter class distribution to obtain a diameter class for

samples in each plot (Madgwick, 1963; Buirkhart and Strub, 1973). With-

in each plot a random tree of the specified diameter class was felled

and sampled. Mensurational dlata for the five trees sampled are in Table

20. Tree height ranged from 10.6 to 14 m with dhh ranging from 10.7 to

15.8 cm. Basal area averaged 0.0134 m2/tree and crown length averaged

35% of total height. Averages were calculated on the basis of the five

trees harvested.

No root sampling was attempted in this experiment.


Biomass Distribution in the Above Ground Portion of the Trees

Total tree weights for the harvested trees ranged from 32 to 75

kg/tree with the stem and bark accounting for the largest portion of

the weight (Table 20). An average of 84.2% of the total above ground

tree weight was bark and stem. Dead branches averaged 2.7% of the

total, live branches averaged 7.1%, and foliage averaged 6% of the











total tree weight. An average of 74% of the total foliage on the trees

at time of harvest was 1974 foliage. Little or no foliage prior to 1973

origin was detected on the sample trees.

Inner and outer bark volume of the sample tree was calculated

using Smalian's combined formula. Loss of bark in cutting sample discs

invalidated actual bark measurements so bark volume was taken as the

difference between the two calculated volumes. The volume of wood, times

its specific gravity of 0.48 (Gooding, 1970), was used to determine the

weight proportion of bark free stem in thle sample trees. Bark weight

could then be taken as the difference between the total stem weight and

the calculated wood weight. Averages of 31 and 53% were found for the

bark and wood portions of above ground biomass. While the bark may be

overestimated, the bark thickness did not vary greatly from reported

values for slash pine (Phillips and Schroeder, 1972).

WJhen compared to the local volume formula used in the initial

stand volume calculation, Smalian's inner bark formula correlated very

highly with local volume (Fig. 11) but thie local volume formula over-

estimated the inner bark volume on the sample trees by an average of

26%.

Nearly perfect agreement was found when the foliage formula of

Mead (1971) was compared with the actual foliage of the sample trees

(log foliage = 0.5325 + 2.6208 10g dbh). The correlation coefficient

was 0.999 (measured foliage = 0.5679 + 0.8076 calculated foliage).

Treatment appeared to affect the retention of 1973 needles (Table 20).

The 1973 needles accounted for 20% of the foliage in the no K treat-

ments and 27-40% of the foliage in treatments receiving K in the un-

replicated samples.





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Stem wood of 8-year-old slash pine in Miississippi and in North

Carolina has been shown to make up approximately 40% of the total above

ground biomass with stem bark accounting from 12 16%, branches 20 21%

and foliage 22 23% (Nemeth, 1973; MicKee and Shoulders, 1974). Mlead

(1971) found 15% bark, 52% bole wood, 6% live branches, and 6% foliage

in 13-year-old slash pine. In older trees the bole wood in slash pine

was 57 60% of the total above ground biomass, branches were 3 4%,

and needles were 3.5 5.0% of the total (Koch, 1972). Loblolly pine

had larger proportions of stem wood and less bark, branches, and needles

than slash pine at comparable ages (Metz and Wells, 1965; Wells and

Jorgensen, 1973; Walker, 1973).

Radiata pine had biomass distribution similar to slash and

loblolly pine (Orman and Will, 1960; Ovington et al., 1967). Root

biomass for slash pine was 16 and 26% of the above ground biomass

(White et al., 1971; Koch, 1972).


Comparison of Nutrient Contents in Various Parts of the Tree

Concentrations of nutrients by treatment for the various compo-

nents of the harvested trees are presented in Table 21. From an exami-

nation of the unreplicated data it appeared that few differences due to

treatment existed. Possible exceptions were found in the 1973 foliage,

live branch, and bark K concentration in trees fertilized at 192 kg

K/ha. Average biomass and nutrient contents for the plantation totaled

84.5 t/ha of above ground tree biomass containing 58 68 kg K/ha, 10.3

kg Na/ha, 120.3 kg Ca/ha, 27.2 kg Mlg/ha, and 15.6 kg P/ha (Table 22).

With the exception of Ca, these compared with 8-year-old slash pine

grown on silt loam soil in Mississippi (McKee and Shoulders,1974) of


















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