• TABLE OF CONTENTS
HIDE
 Front Cover
 Title Page
 Acknowledgement
 Table of Contents
 I. Introduction
 II. Review of literature
 III. Experimental responses to...
 IV. Soil sampling in sugarcane...
 V. Determination of fertilizer...
 VI. Making fertilizer recomend...
 VII. Summary
 VIII. References
 Back Cover
 Historic note






Group Title: Bulletin - Agricultural Experiment Stations, University of Florida ; 809 (technical)
Title: Responses to phosphorus and potassium and fertilizer recommendations for sugarcane in south Florida
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Full Citation
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Permanent Link: http://ufdc.ufl.edu/UF00027454/00001
 Material Information
Title: Responses to phosphorus and potassium and fertilizer recommendations for sugarcane in south Florida
Series Title: Bulletin Agricultural Experiment Stations, University of Florida
Physical Description: 29 p. : ill. ; 23 cm.
Language: English
Creator: Gascho, Gary John
Kidder, Gerald, 1940-
Publisher: Agricultural Experiment Stations, Institute of Food and Agricultural Sciences, University of Florida
Place of Publication: Gainesville Fla.
Publication Date: 1979
 Subjects
Subject: Sugarcane -- Fertilizers -- Florida   ( lcsh )
Potassium fertilizers   ( lcsh )
Phosphatic fertilizers   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 28-29.
Statement of Responsibility: G.J. Gascho and G. Kidder.
 Record Information
Bibliographic ID: UF00027454
Volume ID: VID00001
Source Institution: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000401558
oclc - 10705588
notis - ACE7406

Table of Contents
    Front Cover
        Front Cover
    Title Page
        Title Page
    Acknowledgement
        Acknowledgement
    Table of Contents
        Table of Contents 1
        Table of Contents 2
    I. Introduction
        Page 1
    II. Review of literature
        Page 1
        Page 2
    III. Experimental responses to phosphorus and potassium
        Page 2
        Page 3
        Page 4
        Page 5
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
        Page 12
        Page 13
        Page 14
    IV. Soil sampling in sugarcane fields
        Page 15
        Page 16
        Page 17
        Page 18
        Page 19
        Page 20
    V. Determination of fertilizer recomendations for phosphorus and potassium
        Page 21
        Page 22
        Page 23
        Page 24
    VI. Making fertilizer recomendations
        Page 25
        Page 26
    VII. Summary
        Page 27
    VIII. References
        Page 28
        Page 29
    Back Cover
        Page 30
    Historic note
        Page 31
Full Text


CEMBER 1979


BULLETIN 809 (TECHNICAL)


Responses to Phosphorus and
Potassium and Fertilizer
Recommendations fQr-Sugarcane
in South Florida

3. J. GASCHO AND G. KIDDER '" 0o
';' I/ "" /


AGRICULTURAL EXPERIMENT STATIONS
INSTITUTE OF FOOD AND AGRICULTURAL SCIENCES
UNIVERSITY OF FLORIDA, GAINESVILLE
F. A. WOOD, DEAN FOR RESEARCH












RESPONSES TO PHOSPHORUS AND POTASSIUM
AND FERTILIZER RECOMMENDATIONS FOR
SUGARCANE IN SOUTH FLORIDA



G. J. Gascho and G. Kidder


This public document was promulgated at an annual cost of $1774.90 or
a cost of 88.7 per copy to provide information on fertilization of sugar-
cane.


AUTHORS
Dr. Gascho is a Professor (Plant Nutrition) and Dr. Kidder is an Assistant
Professor (Sugarcane Extension), Agricultural Research and Education Center,
Institute of Food and Agricultural Sciences, The University of Florida, P.O.
Drawer A, Belle Glade, Florida 33430.




















ACKNOWLEDGMENTS

The soil test-fertilization correlation experiments reported in this bulletin
were conducted on the Farms of the Florida Sugar Corporation (the farm is now
part of Talisman Sugar Corporation), A. Duda and Sons, and Harley Watson.
One soil-sampling study was conducted in fields of the New Hope Sugar Com-
pany. The sugarcane growers of these companies were all generous in supply-
ing assistance and equipment and helpful in scheduling the field operations. In
addition to these growers, thanks are also due to Dr. F. H. Thomas, formerly
assistant soil chemist at Belle Glade, who conducted one soil sampling experi-
ment; to C. E. Freeman for help in devising the fertilizer recommendation
system; to Dr. J. R. Orsenigo for help in harvesting; to Drs. H. W. Burdine, G.
H. Snyder, and F. G. Martin for consultation and help with plant nutritional and
statistical aspects of the work; and to Mrs. C. V. Deaton and Mrs. M. G.
Whitehurst for analyses of soil and plant tissues.
















CONTENTS

Page
I. INTRODUCTION ...................................... 1

II. REVIEW OF LITERATURE ............................... 1
III. EXPERIMENTAL RESPONSES TO PHOSPHORUS
AND POTASSIUM ..................................... 2
A. Materials and Methods ............................... 2
B. Results and Discussion ............................. 5
1. Soil test values ................... ........... 5
2. Tissue test values .............................. 8
3. Shoot counts and lengths ......................... 11
4. Yield parameters .............................11
IV. SOIL SAMPLING IN SUGARCANE FIELDS .................. 15
A. Experimental Procedures .......................... 17
1. Standard deviations in experimental plots ............ 17
2. Depth and position of sampling .................... 17
3. Number of samples needed .................. .... 17
B. Results and Discussion .............. ............... 19
1. Standard deviations in experimental plots ............ 19
2. Depth and position of sampling .................... 19
3. Number of samples needed ....................... 19
V. DETERMINATION OF FERTILIZER RECOMMENDATIONS
FOR PHOSPHORUS AND POTASSIUM ..................... 21
A. Experimental Procedures .......................... 21
B. Results and Discussion .............. ............... 21

VI. MAKING FERTILIZER RECOMMENDATIONS ................ 25
VII. SUMMARY ........................................... 27
VIII. REFERENCES ..........................................28








I. INTRODUCTION

Sugarcane has often been described as the crop capable of most effi-
ciently utilizing the energy of the sun. Under the best, most intensive manage-
ment, it is possible that the photosynthetic capabilities of the sugarcane plant
are the only limiting factors in sugar production. It can safely be said, however,
that this ideal has not been reached in commercial practice, where water con-
trol, insects, weeds, plant nutrition, and a multitude of other factors limit pro-
duction. Experiments over the past 50 years have shown that deficiencies or
excesses of phosphorus (P) or deficiencies of potassium (K) can be listed
among the factors limiting sugarcane and sugar yields.


II. REVIEW OF LITERATURE
A sugarcane crop of 50 tons per acre will normally remove from the soil
about 50 to 60 pounds per acre of P2 05 (Barnes, 1974). Those amounts plus
additional amounts to satisfy soil fixation and/or other losses must be supplied
in order to continuously grow high-yielding cane crops. In a study on Florida
organic soils, Andreis (1975) found that only 29 pounds of P2 05 were removed
from the soil to produce a 40-ton crop (36 pounds for a 50-ton crop).
A review of Florida literature on the effects of P on sugarcane indicates
that Allison (1932) recognized that high levels of soluble phosphate fertilizers
could be injurious to sugarcane. The detrimental effects of high levels of phos-
phates in cane juice, reduced sucrose content, and even reduced sugarcane ton-
nage due to high available soil and/or applied P have been reported by several
researchers. Neller (1942) found the highest sugar yield in plant cane when no P
was applied. He found that P in cane juice increased with rate of P applied. In a
later publication, Neller (1945) reported a reduction in growth due to heavy
applications of superphosphate. Le Grand and Thomas (1963) reported reduced
tonnage of cane and decreased juice Brix due to high soil P. Bourne (1950)
reported that P applied at planting increased cane and sugar tonnage per acre in
a first ratoon crop over that obtained in the plant crop. Le Grand, Burdine, and
Thomas (1961) found that sugarcane tonnage in the first ratoon was increased
over check for 40 pounds of P2 05 per acre applied in the plant crop.
More studies with P rates were necessary to find the rate of P that would
produce the maximum sugar in a three-harvest cycle of sugarcane, as previous
fertility trials were either plant cane only or plant cane plus first ratoon. The
early experiments were not consistent with normal commercial practices,
where one planting is expected to produce for at least two ratoons. Since high-
soluble P has limited sucrose concentrations in the plant crop and increased ton-
nages in the first ratoon, it is likely that a compromise in sucrose content may be

1. All measures are given in the English system. Conversion factors to calculate metric
equivalents are given in Table 11.








I. INTRODUCTION

Sugarcane has often been described as the crop capable of most effi-
ciently utilizing the energy of the sun. Under the best, most intensive manage-
ment, it is possible that the photosynthetic capabilities of the sugarcane plant
are the only limiting factors in sugar production. It can safely be said, however,
that this ideal has not been reached in commercial practice, where water con-
trol, insects, weeds, plant nutrition, and a multitude of other factors limit pro-
duction. Experiments over the past 50 years have shown that deficiencies or
excesses of phosphorus (P) or deficiencies of potassium (K) can be listed
among the factors limiting sugarcane and sugar yields.


II. REVIEW OF LITERATURE
A sugarcane crop of 50 tons per acre will normally remove from the soil
about 50 to 60 pounds per acre of P2 05 (Barnes, 1974). Those amounts plus
additional amounts to satisfy soil fixation and/or other losses must be supplied
in order to continuously grow high-yielding cane crops. In a study on Florida
organic soils, Andreis (1975) found that only 29 pounds of P2 05 were removed
from the soil to produce a 40-ton crop (36 pounds for a 50-ton crop).
A review of Florida literature on the effects of P on sugarcane indicates
that Allison (1932) recognized that high levels of soluble phosphate fertilizers
could be injurious to sugarcane. The detrimental effects of high levels of phos-
phates in cane juice, reduced sucrose content, and even reduced sugarcane ton-
nage due to high available soil and/or applied P have been reported by several
researchers. Neller (1942) found the highest sugar yield in plant cane when no P
was applied. He found that P in cane juice increased with rate of P applied. In a
later publication, Neller (1945) reported a reduction in growth due to heavy
applications of superphosphate. Le Grand and Thomas (1963) reported reduced
tonnage of cane and decreased juice Brix due to high soil P. Bourne (1950)
reported that P applied at planting increased cane and sugar tonnage per acre in
a first ratoon crop over that obtained in the plant crop. Le Grand, Burdine, and
Thomas (1961) found that sugarcane tonnage in the first ratoon was increased
over check for 40 pounds of P2 05 per acre applied in the plant crop.
More studies with P rates were necessary to find the rate of P that would
produce the maximum sugar in a three-harvest cycle of sugarcane, as previous
fertility trials were either plant cane only or plant cane plus first ratoon. The
early experiments were not consistent with normal commercial practices,
where one planting is expected to produce for at least two ratoons. Since high-
soluble P has limited sucrose concentrations in the plant crop and increased ton-
nages in the first ratoon, it is likely that a compromise in sucrose content may be

1. All measures are given in the English system. Conversion factors to calculate metric
equivalents are given in Table 11.







necessary in the plant crop in order to obtain highest total production from
"planting to plowing." In any event, the need for additional research to con-
sider total sugar production in a three-harvest cycle, as affected by P nutrition,
was evident.
The effects of K nutrition have also been studied since the initiation of the
Everglades Experiment Station in the 1920's, but results have been much less
striking than for P. Potassium has generally given a response in Florida cane
tonnage (Iley and LeGrand, 1964). Stevens (1945) found that 300 pounds of
muriate of potash per acre gave an increased sugar yield over a 200-pound rate.
Le Grand, Burdine, and Thomas (1961) obtained no response to 140 pounds per
acre K 20 when the soil test was a low 16 pounds K per acre by the Everglades
Experiment Station 2 soil test. Bourne (1956) stated that 250 pounds of muriate
of potash (150 pounds K20) is required to maintain a ratoon crop. This is the
same figure necessary for growing 50 tons of cane per acre in other sugarcane
areas (Barnes 1974).
The main objectives of this research were to determine the optimum
levels of P and K to apply in order to obtain the maximum sugar production per
acre over a three-year cycle, i.e., a plant crop plus two ratoon crops.


III. EXPERIMENTAL RESPONSES TO
PHOSPHORUS AND POTASSIUM
A. MATERIALS AND METHODS
Randomized complete block experiments with five replications were
conducted at three locations. The experiments at Locations 1 and 2 were facto-
rials with varying levels of both P and K fertilizers applied. At Location 3 only
P was varied. Individual plots were four 5-foot rows, 43.5 feet in length, i.e.,
0.02 acre. Basic soil properties, the location of the experiments, and other de-
tails are given in Table 1.
Soil samples were collected from each block after the soil was thoroughly
disked prior to fertilization. The sampling depth was 0 to 12 inches for all sam-
ples. Twenty-core composite samples were collected prior to planting; thereaf-
ter, nine-core composite samples were collected from individual plots. The tim-
ing of these latter samplings was: (1) 6 to 8 weeks after fertilization, (2) May,
(3) August, (4) February or March (after harvest) for each crop year. All sam-
ples were sieved, air-dried, and analyzed for pH, P, and K at the Soils Labora-
tory of the AREC. The procedures used have been described by Thomas
(1965). Because the calculations of the soil laboratory assume a 0 to 6-inch
sampling depth and the recommended sampling depth for sugarcane is 0 to 12
inches, all soil tests are presented as unitless values.

2. The present name is the Agricultural Research and Education Center, Belle Glade,
hereafter referred to as the AREC.







necessary in the plant crop in order to obtain highest total production from
"planting to plowing." In any event, the need for additional research to con-
sider total sugar production in a three-harvest cycle, as affected by P nutrition,
was evident.
The effects of K nutrition have also been studied since the initiation of the
Everglades Experiment Station in the 1920's, but results have been much less
striking than for P. Potassium has generally given a response in Florida cane
tonnage (Iley and LeGrand, 1964). Stevens (1945) found that 300 pounds of
muriate of potash per acre gave an increased sugar yield over a 200-pound rate.
Le Grand, Burdine, and Thomas (1961) obtained no response to 140 pounds per
acre K 20 when the soil test was a low 16 pounds K per acre by the Everglades
Experiment Station 2 soil test. Bourne (1956) stated that 250 pounds of muriate
of potash (150 pounds K20) is required to maintain a ratoon crop. This is the
same figure necessary for growing 50 tons of cane per acre in other sugarcane
areas (Barnes 1974).
The main objectives of this research were to determine the optimum
levels of P and K to apply in order to obtain the maximum sugar production per
acre over a three-year cycle, i.e., a plant crop plus two ratoon crops.


III. EXPERIMENTAL RESPONSES TO
PHOSPHORUS AND POTASSIUM
A. MATERIALS AND METHODS
Randomized complete block experiments with five replications were
conducted at three locations. The experiments at Locations 1 and 2 were facto-
rials with varying levels of both P and K fertilizers applied. At Location 3 only
P was varied. Individual plots were four 5-foot rows, 43.5 feet in length, i.e.,
0.02 acre. Basic soil properties, the location of the experiments, and other de-
tails are given in Table 1.
Soil samples were collected from each block after the soil was thoroughly
disked prior to fertilization. The sampling depth was 0 to 12 inches for all sam-
ples. Twenty-core composite samples were collected prior to planting; thereaf-
ter, nine-core composite samples were collected from individual plots. The tim-
ing of these latter samplings was: (1) 6 to 8 weeks after fertilization, (2) May,
(3) August, (4) February or March (after harvest) for each crop year. All sam-
ples were sieved, air-dried, and analyzed for pH, P, and K at the Soils Labora-
tory of the AREC. The procedures used have been described by Thomas
(1965). Because the calculations of the soil laboratory assume a 0 to 6-inch
sampling depth and the recommended sampling depth for sugarcane is 0 to 12
inches, all soil tests are presented as unitless values.

2. The present name is the Agricultural Research and Education Center, Belle Glade,
hereafter referred to as the AREC.







Triple superphosphate (46% P2 0 ) and muriate of potash (60% K20)
were mixed together for the equivalent P2 05 and K 20 rates indicated in Tables
4 and 5. After soil sampling, P and K fertilizer for the plant crop was evenly
broadcast over each individual plot. The rates were chosen to have a middle rate
that conformed to previous fertilizer recommendations.
The plots were then disked to a depth of 8 inches to mix the fertilizer with
the soil. Manganese, copper, zinc, and boron were supplied in the furrows prior
to planting at rates of 16, 8, 8, and 3 pounds per acre, respectively.
For the ratoon crops the same sources of P and K were broadcast on the
soil surface, but no micronutrients were applied. The fertilizer was incorpo-
rated with soil by cultivation with a rolling cultivator. In each case the middle
rate was calculated to raise the soil-test level to that previously recommended at
the AREC, i.e., 5 for P and 150 for K, using the ratios of 20 pounds per acre of
P2 Os to raise soil P by 1 and 2 pounds per acre of K20 to raise the soil K by 1
unit (Forsee, Green, and Webster, 1954).
Double rows of cane stalks were laid in each furrow, cut to 18-inch
lengths, and covered. All cultural practices, except for fertilization, were the
same as those maintained in the commercial fields.
Ten TVD (top visible dewlap) leaf blades were randomly collected from
the interior two rows of each plot in May and August for the plant and first
ratoon crops. The midribs were stripped from the leaves and discarded. The
laminae were dried at 70 C, ground to 2 mm, and digested with perchloric acid
(Gieseking et al., 1935). Phosphorus was determined by colorimetry following
color development as molybdivanadophosphate (Gee and Deitz, 1953). Potas-
sium was determined by atomic absorption spectroscopy (Reference 2).
At Location 1, counts of total shoots were made in the plant cane in April
and May, and stalk length was measured from the ground surface to the TVD in
April, May, June, and July. Counts of millable stalks were made in all plots in
September of each year.
At harvest, the cane was burned to remove excess leaves, then cut at the
ground surface by machete. Tops were removed by cutting at the top hard in-
ternode and were discarded. The cane from each plot was weighed, and 10-
stalk samples were collected for juice analysis. All remaining cane stalks were
then removed to a commercial mill.
The 10-stalk samples were passed through a 3-roller sample mill to ex-
press the juice, which was analyzed for Brix by hydrometer and for pol with a
polariscope after the addition of lead subacetate and filtering. The percent su-
crose in the juice was determined using Schmitz's tables (Spencer and Meade,
1945). The amount of sugar per ton of cane was calculated using the Winter-
Carp-Geerlig formula as modified by Arceneaux (1935) and the varietal correc-
tion factors of Rice and Hebert (1971). Sugar per acre was calculated from the
cane weights and theoretical sugar per ton of cane.














Table 1. Location of phosphorus and potassium experiments; soil type; AREC soil test values, prior to experimentation; cane variety; and planting
and harvesting dates.
Location
No. Farm name, site Soil Type pH P K Variety of Cane Planted Harvested
1 Florida Sugar t
13 mi. east of Belle
Glade Pahokee muck 6.2 2 42 CL 41-223 11-68 2-70 1-71 1-72
2 R.I.B. Sugartt
15 mi. south of Okeelanta
Clewiston sandy muck 5.6 2 39 CP 63-588 12-69 12-70 12-71 12-72
3 H. Watson Farm,
Lake Harbor Torrymuck 5.7 4 162 CL 41-223 11-68 1-70 2-71 12-71

t Florida Sugar Corporation is now a part of Talisman Sugar Company.
tt R.I.B. Sugar is now a part of A. Duda and Sons Farms.







Analysis of variance, standard deviation, and linear regression were used
to help interpret the data.

B. RESULTS AND DISCUSSION
1. SOIL-TEST VALUES
Soil-test values for P and K varied with rate of application and season (Fig-
ures 1 to 4). In general, soil test levels increased in proportion to the rate of appli-
cation for samples taken 6 to 8 weeks following application. The levels de-
creased greatly during the summer-growing season but increased slightly in the
winter after harvest but prior to fertilizer applications on the ratoons.

Phosphorus
At Location 1, soil samples taken 6 weeks after application had soil test
values of 2, 16, and 31 for application rates of 0, 100, and 200 pounds per acre of
P2 05, respectively (Fig. 1). Approximately 7 pounds per acre of P2 05 was re-
quired to raise the soil-test value 1 unit on Pahokee muck. At Location 2, (Fig. 2)
the corresponding soil-test values were 2, 3, 4, 5, and 7 following application of


I

P RATE 2





-P RATE I


FERTILIZATION




HARVEST


SOIL SAMPLING


0 20 30 41
0 10 20 30 4(


MONTHS

Figure 1. Soil test phosphorus by AREC, Belle Glade methods as affected by P applica-
tion and three years of sugarcane at Location 1 (Pahokee muck).


30-




0.
20-

w
I-
t-

ci) 10-





0
O-













6-



I-
C- ,
W 41 3


2 T






0
0 6 12 18 24 30

MONTHS

Figure2. Soil test phosphorus by AREC, Belle Glade methods as affected by P applica-
tion and two years of sugarcane at Location 2 (Okeelanta sandy muck).


P at 0, 30, 60, 90, and 120 pounds per acre of P2 05 respectively. From 24 to 30
pounds per acre of P2 05 were required to raise the soil P by 1 unit on Okeelanta
sandy muck. Soil-test data from the Torry muck experimental site was very er-
ratic. No realistic statements can be made about the effects of P application on
soil-test values at that site.
Application of P to the ratoons gave similar results. Approximately 8
pounds per acre of P2 O0 fertilizer were required to raise soil test P by 1 unit for
the Pahokee muck, while on Okeelanta sandy muck 18 to 30 pounds per acre
were required.
The net responses in soil-test P due to fertilization were much higher in the
Pahokee muck than in the Okeelanta sandy muck. The data suggest that soil tests
following fertilization are not adequate guides for fertilization unless good infor-
mation is available for all soil types. The rule of thumb that 20 pounds of P, O0
applied will result in an increase of 1 unit of soil P is only a rough guide. The data
suggest that soil-test results together with harvest data on a given soil type must
be evaluated over a period of years in order to determine the optimum fertilizer
rates.







Potassium
Approximately 3.0 to 3.6 pounds per acre of K20 was required to raise
soil-test K by 1 unit at Location 1 for samples taken 6 weeks after fertilization of
plant cane (Fig. 3), while 2.5 pounds per acre was required in the first ratoon. A
similar response was obtained for the middle K rate in the second ratoon, but no
response was recorded for the high K rate after fertilization of the second ratoon.
At Location 2 (Fig. 4), 3.4 to 4.5 pounds per acre of KO2 was required to raise
soil-test K by 1 unit in plant cane, and 11 to 20 pounds was required in the first
ratoon.
The variable response to K applications, especially for the ratoon crop, is
consistent with the thesis developed later that it is very difficult to obtain a repre-
sentative and meaningful soil test in a ratoon crop. The data presented for K, like
that for P, indicate that soil-test K increases during the winter after harvest but
prior to refertilization. Since the soil contains very low concentrations of native
K, the increase can not be accounted for by soil decomposition. The increase
could be the result of movement of soil K downward beyond the depth sampled
during wet summer weather and then movement upward with drier weather in the










I-
200-K RATE2





u)


oo
K RATE I
100
S) I


K RATE O


Z5"
0 10 20 30 40

MONTHS

Figure 3. Soil test potassium by AREC, Belle Glade methods as affected by K applica-
tion and 3 years of sugarcane at Location 1 (Pahokee muck).








200-






cn K RATE

I4

Ci
100-








0-
0 6 12 18 24 30

MONTHS

Figure4. Soil test potassium by AREC, Belle Glade methods as affected by K applica-
tion and two years of sugarcane at Location 2 (Okeelanta sandy muck).


winter. A second possible explanation is that the ash after burning cane and the
unburned tops are returned to the soil and are contributing to the increased soil K
levels in the 0 to 12-inch surface soil.
2. TISSUE-TEST VALUES
Added increments of fertilizer P and K resulted in increased levels of these
elements in TVD leaf blades at Locations 1 and 2 (Table 2). The rate of increase
(slope) was more pronounced for tissue samples taken in April or May than for
samples taken in August. This result suggests a rapid uptake of nutrients early in
the growing season followed by dilution through growth during the remainder of
the growing season. No statistically significant response of TVD leaf-blade P
was obtained as a function of its rate of application at Location 3. Applied P
fertilizer was not being utilized by plants on the Torry muck soil, either because
of soil fixation or because the plant did not need the P and therefore rejected it by
selective uptake phenomena. Because there were no significant relationships be-
tween tissue and applied levels at Location 3, the data from that location are ig-
nored in the remainder of this section. More experimentation is needed to de-
scribe any responses to P and K on Torry muck.









Table 2. Linear regression of concentration of phosphorus and potassium in TVD leaf
blades on phosphorus and potassium fertilization rates. (Equations are expres-
sion of % tissue P or K as a function of pounds P2 05 or K2 0 applied per acre).


Nutrient Location
P 1



2


3t


1



2


tRegressions based on data from Location 3 were not statistically significant.




With one exception, concentrations of both P and K were higher in the
zero-level plots of plant cane tissue than in ratoons for a given location and sam-
ple month. The decreased concentrations in ratoon crops are likely related to
reduced vigor and growth of ratoons compared to plant crops. Concentration of
P in leaf blade tissue increased with age in a given crop year. This increase
could be explained by release of native soil P from the organic soil by mineral-
ization during the growing season. Since the soils studied do not have much
native soil K, it was not surprising that the level of K in the tissue decreased
with crop age. The levels of P in the TVD leaf blades of zero-level plots were,
except for the plant crop at Location 2, in the range where response in yield
parameters could be expected due to application.3 By contrast, response to K
fertilization could be expected only for the ratoon crop at Location 2 according
to tissue K levels.


3. Unpublished data of Gascho et al.


Crop Sample
Year Month
plant April
August
ratoon 1 May
August
plant May
August
ratoon 1 May
August
plant April
August
ratoon 1 May
August
ratoon 2 May

plant April
August
ratoon 1 May
August
plant May
August
ratoon 1 May
August


2.47
1.48
1.72
1.62
1.36
1.11
0.75
0.93


Slope x 10 4
+8.55
+3.40
+33.8
+1.40
+5.13
+2.47
+6.70
+5.20
-8.00
-1.00
+0.52
+0.62
+0.05


+ 15.9
+1.59
+9.72
+8.33
+13.1
+8.75
+8.60
+9.20


Intercept
0.179
0.180
0.118
0.164
0.247
0.249
0.156
0.199
0.185
0.216
0.208
0.209
0.188














Table 3. Effect of phosphorus and potassium rates on plant cane shoot count and length to the TVD at Location 1.

(Shoots/acre) x 10-4 Length (cm) tt
April 9 May 27 April 9 May 14 June 13 July 30
Phosphorus rate
lb P2 05/acre

0 2.56B t 2.88 10 B 22 B 71 B 166 B
100 3.52 A 3.24 12 A 29 A 91 A 184 A
200 3.60 A 3.67 13 A 30 A 97 A 190 A

Potassium rate
lb K2 O/acre

0 3.28 3.06 11 26 84 179
220 3.31 3.28 12 27 86 177
440 3.07 3.45 12 28 89 182
t Values within a given group of 3, followed by the same letter, are not significantly different at the 0.05 level by Duncan's multiple range test.
tt Centimeters x 0.39= inches.







3. SHOOT COUNTS AND LENGTHS
Phosphorus rate affected both the shoot count and the length of plant cane
from the soil to the TVD at Location 1 (Table 3). In the zero-P plots the cane
was significantly shorter and the stalk count was lower than in plots where P
was added. This result is consistent with the observations that tissue P concen-
trations were below critical levels for the zero-P plots, and P deficiency results
in poor stands and short cane. Early stand counts and plant height were not af-
fected by K rate. This result was anticipated, since the K tissue levels indicated
no K deficiency. However, the soil-test levels were at very low levels during
the growing season and would have indicated below-optimum growth. As is
discussed later, the highest P rates, which gave highest shoot counts, did not
produce the most sugar per acre.
4. YIELD PARAMETERS
Calculated sugar yields and sugarcane and sugar tonnages for the various
P rates at the three locations are given in Tables 4 and 5. Since the original soil
tests were less than 5 for all three locations, a response was anticipated, espe-
cially at Locations 1 and 2, where the before-planting soil tests were 2 (Table
1). Tissue analysis indicated P deficiency conditions for the zero-P plots in the
plant crop at Location 1 but not at Location 2, and deficiency for P in both loca-
tions for first ratoons (Table 2).
At Location 1, sucrose concentration in the cane decreased with increas-
ing P rate while sugarcane tonnage increased (Table 4). Because of the inverse
results between sucrose concentration and cane tonnage, there were no differ-
ences in sugar per acre. Effects noted due to K application were similar to those
for P applications. No previous reports of reduced sucrose due to K application
were found in the Florida sugarcane literature.
First ratoon sugarcane and sugar tonnages were highest at the intermedi-
ate rate of P fertilization. Again, high rates of K decreased the sucrose concen-
tration, but this loss was compensated for by higher tonnages; therefore the
sugar per acre was not changed due to K fertilization. Sucrose concentrations in
the second ratoon crop were not significantly different due to either P or K fer-
tilization. The intermediate rate of P increased tonnages of sugarcane and sugar
greatly over the check plots. The highest P rate did not increase tonnages over
the middle rate. Both sugarcane and sugar tonnage in the second ratoon were
increased to the highest rate of K. No significant difference in total sucrose due
to K rate was recorded in three years. The differences in tonnages noted in the
second ratoon indicate that a difference could be expected if a third ratoon had
been considered. The results at Location 1 indicate that the benefits due to P and
K fertilization are more apparent in ratoons than in the plant cane. This ratoon
effect is more pronounced for P than for K.
Data from Location 2 are also presented in Table 4. Careful examination
of these data would result in conclusions similar to those made for Location 1.
Sucrose concentration was decreased by both P and K applications, but because







Table 4. Theoretical yield of sugar per ton of cane and tonnages of sugarcane and sugar as affected by phosphorus fertilization rate at three locations.

Rate of P20 Application Plant Ratoon 1 Ratoon 2
Plant Ratoon I Ratoon 2 Yieldt TCAtt TSAt Yield TCA TSA Yield TCA TSA
--- ---- lbacre -----------------
LOCATION
0 0 0 222 46.6 5.2 269 26.6 3.6 219 27.2 3.0
100 25 30 211 51.3 5.4 281 39.2 5.5 223 33.0 3.6
200 50 60 203 51.2 5.2 269 38.4 5.1 215 33.0 3.6

Significance level, P = 0.01 0.05 N.S. 0.01 0.01 0.01 N.S. 0.01 0.1

LOCATION 2
0 0 24 218 60.1 6.6 263 34.4 4.5 257 28.1 3.6
30 30 24 210 60.4 6.3 258 38.6 5.0 247 37.4 4.5
60 60 24 210 60.8 6.4 252 38.4 4.9 252 41.1 5.1
90 90 24 210 59.8 6.3 254 38.3 4.9 250 40.3 5.0
120 120 24 211 59.8 6.3 252 37.9 4.8 249 42.9 5.4

Significance level, P =0.1 N.S. N.S. 0.01 0.05 N.S. N.S. 0.01 0.01

LOCATION
0 0 0 234 86.6 10.1 265 71.0 9.4 256 61.3 7.5
60 60 0 228 84.5 9.6 267 76.9 10.3 239 57.5 6.9
120 120 0 231 89.5 10.3 267 75.1 10.0 241 57.4 6.9


Significance level, P = N.S. N.S. N.S..
STheoretical yield of sugar per ton of cane from Winter -Carp- Geerligs' Formula.
tt Tons of cane per acre.
Tons of sugar per acre.


N.S. N.S. N.S. N.S. 0.05 0.05











Table 5. Theoretical yields of sugar per ton of cane and tonnages of sugarcane and sugar as affected by potassium rate at two locations.


Rate ofK2 0 Application Plant Ratoon 1 Ratoon 2
Plant Ratoon I Ratoon 2 Yield t TCA tt TSA Yield TCA TSA Yield TCA TSA
--------------------- lbacre ------------------
LOCATION 1
0 0 0 216 48.9 5.3 280 34.4 4.8 222 28.6 3.1
220 180 30 213 48.1 5.1 272 34.4 4.7 222 31.0 3.4
440 360 60 208 52.0 5.4 267 35.4 4.7 213 33.8 3.6
Significance level, P= 0.1 0.1 N.S. 0.01 N.S. N.S. N.S. 0.01 0.1
LOCATION 2
0 0 180 225 55.7 6.3 262 33.8 4.4 257 28.1 3.6
120 100 180 216 58.4 6.3 256 37.8 4.8 247 37.4 4.6
240 200 180 209 60.9 6.4 260 37.2 4.8 252 41.1 5.1
360 300 180 209 61.9 6.5 253 38.0 4.8 250 40.3 5.0
480 400 180 200 64.0 6.4 248 40.8 5.0 249 42.9 5.4


Significance level, P= 0.01 0.01 N.S.
tTheoretical yield of pounds of sugar per ton of cane from Winter-Carp-Geerligs' formula.
ttTons of cane per acre.
*Tons of sugar per acre.


0.01 0.01 N.S. N.S. 0.01 0.01








of the greater tonnage of cane, no differences were noted in sugar tonnage for
the plant crop. The large reduction in sucrose offset by higher tonnage of sugar-
cane was no doubt due to the behavior of K in this particular soil (Okeelanta
sandy muck). Periodic soil sampling and analysis for K indicated that heavy
rains in early summer moved K to levels below the 12-inch rooting zone. This K
moved upward during the fall as the soil dried and sub-surface irrigation began.
Apparently the upward movement of K stimulated late growth and consump-
tion of stored sugars.
With successive ratoons, the beneficial effects of P fertilization were
more noticeable. Sugarcane and sugar tonnages for the zero-P plots continued
to decrease for the second ratoon crop despite the application of 25 pounds per
acre of P2 05. A P deficiency in the plant crop cannot easily be corrected in
ratoon crops. On the other hand, application of 180 pounds per acre of K2O to
the zero K plots in the second ratoon seemed adequate to restore tonnages to
levels close to those obtained in plots receiving K each year. Total sugar pro-
duction for three years was increased above check for rates up to the middle rate
of P2 05. The total application for the middle rate was 144 pounds per acre.
There was a trend for higher total sugar for plots receiving K, but no significant
differences were found.
The third experiment, conducted on Torry muck near the shores of Lake
Okeechobee, resulted in data which are of limited utility (Table 4). Adequate
available soil P persisted throughout the three-year experiment in plots receiv-
ing no applied P. Available P was confirmed by soil test data throughout the
experiment as well as by sugarcane data shown in Table 4. Because of the fail-
ure to obtain a response to P in this experiment, these data were not useful in
developing fertilizer recommendations but do show the ability of Torry muck
soil to maintain high fertility levels and high sugarcane and sugar yields.
The increased stalk count in plots due to P fertilization contributed signif-
icantly to sugar production. However, stalk count increased linearly with P
rate, while yield of sugar increased quadratically. Figure 5 clearly shows that
maximum sugar was produced at 78 stalks per 20 feet of row (ca. 34,000 stalks
per acre) even though higher stalk counts in the second ratoon field were in-
duced by the highest P treatments on Okeelanta sandy muck.
Interactions between P and K rates were not significant at the 0.05 level
and are not presented.
Data for total sugar per acre at Locations 1 and 2 as affected by P rate were
submitted to curviliner regression analysis using the quadratic equation:
Y= a + bX + cX2,
where Y = total tons of sugar per acre for three harvests, X = total pounds of
P2 05 applied to the three crops, and a, b, and c are regression coefficients (Fig-
ure 6). Maximum sugar was obtained by applications of 200 and 210 pounds
per acre of P2 05 for Locations 1 and 2, respectively.













0
UL MAXIMUM SUGAR/ACRE
1i-:
0 75-











POUNDS OF P,20/ACRE IN 3 YEARS
*The regression is significant at the 0.05 level.X, R0.778








Data from these experiments did not describe a maximum tonnage of
0 155 310

POUNDS OF P2O/ACRE IN 3 YEARS

Figure 5. The effect of applied P on stalk population and the point of maximum sugar
per acre on stalk population for September stalk counts in the first ratoon crop
at Location 2 (Okeelanta sandy muck).
*The regression is significant at the 0.05 level.


Data from these experiments did not describe a maximum tonnage of
sugar per acre due to K fertilization. Any increases in TCA were nullified by
decreasing sugar yield, resulting in relatively unchanged TSA with varying K
rates. This effect has often been described for P on Everglades soils but has not
previously been reported for K, and is contrary to the generally accepted opin-
ion that K improves juice quality. The response to K is illustrated in Figure 7 for
the data from plant cane at Location 2.


IV. SOIL SAMPLING IN SUGARCANE
FIELDS
It is customary in the Everglades Agricultural Area to take soil samples
annually. When this custom, a carry-over from the intensive vegetable produc-
tion in the area, is followed in sugarcane cultivation, soils are sampled in ratoon
cane fields, and the test results are used to guide ratoon fertilization. Soil sam-
ples from ratoon fields have shown considerable variation in soil-test values,
variation much greater than that found in samples taken prior to planting when
the soil is thoroughly mixed. Apparently, the fertilizer placement in previous
crops, the depth and location of the sample, and nutrient gradients in the soil
created by crop uptake are responsible for the unusually high variation in ratoon















16-


S- Y= 14.607 + 0.020 X- 0.00004 X2, R=0.707**
=> ----S--^----,


0 X2

SI- / Y=ll.743+0.030X-0.00007X2, R=0.958*
12- /





0 100 200 300
POUNDS OF P205/ACRE IN 3 YEARS

Figure 6. Yields of sugar per acre over three years as affected by rate of P application
for Location 1 (- Pahokee muck) and Location 2 (- Okeelanta sandy
muck).
**Regressions are significant at the 0.01 level.
Arrow denotes maximum yields.

fields. Fertilizer recommendations based on soil samples which may not be rep-
resentative of the field from which they are taken are of questionable value.
Annual soil testing is not a general practice in field crops. In some sugar-
cane areas soils are only tested prior to planting, and fertilization for both plant
and ratoon crops is based on these tests. 4 5
The objectives of this study were: (1) to compare the variation in soil-test
values of samples taken prior to planting with the variation in samples taken in
fields prior to ratooning, (2) to study the variations associated with samples
taken in ratoon fields at different points across the rows and at different depths
in order to estimate the number of soil cores needed to obtain a reasonably con-
sistent soil test in a ratoon field, and (3) to incorporate the results into a soil
testing system which could be used to advise sugarcane growers on sampling
methods and fertilizer needed for optimum sugar production.

4. Preparation of whole cycle fertilizer recommendations using soil analysis A re-
port of the South African Sugar Association.
5. H. J. Andreis, personal communication relative to the soil testing system of the
United States Sugar Corporation.


I I I I I








I I I I


LBS. SUGAR/TON OF CANE ,
w --
z 2 Y=223.200-0.048X, R=0.968** //
< 220-
0 w

o 215 W
a. -60 )

3 210 0
uLL z
o 205
z Y=56.172+0.017X, R=0.989**
0 TONS OF CANE/ACRE
200 56
0 100 200 300 400 500
POUNDS OF K20/ACRE IN 3 YEARS

Figure 7. Effect of K fertilization on sugarcane tonnage and sugar per ton of cane in the
plant crop at Location 2 (Okeelanta muck).
**Regressions are significant at the 0.01 level.




A. EXPERIMENTAL PROCEDURES

1. STANDARD DEVIATIONS IN EXPERIMENTAL PLOTS
Soil-test data from Experiments 1 and 2 were used to calculate standard
deviations for samples obtained prior to plant, first, and second ratoon crops.

2. DEPTH AND POSITION OF SAMPLING
Two first-ratoon fields on Pahokee muck were sampled to compare the
influence of depth and position in the row on soil-test results. The specific posi-
tions of the samples are given in Table 7.

3. NUMBER OF SAMPLES NEEDED
Three other commercial cane fields were sampled in another experiment.
The fields were divided into areas 25 feet (five rows) wide by 100 feet. One area
in each 2.4 acres was randomly selected for sampling. Field 1 was approxi-
mately 24 acres in size, and 10 areas were selected from that field. Fields 2 and
3 were 38 and 37 acres in size, and 16 areas were selected from each. From each
area, three different rows were randomly selected. The first, second, and third
rows selected were 25, 50, and 100 feet, respectively, from the east end of the
area being sampled. Each row was sampled at five places on a line transversing
the row. The first sample was taken 18 inches from the row; the second, 6
inches from the row; the third, directly in the row; the fourth, 12 inches from the
row (opposite side from the first two); the fifth, 24 inches from row (same side


225-








of row as the fourth sample). These samples were brought into the soil-testing
laboratory, air dried, and screened; pH, P, and K were determined on each sam-
ple. The samples were run through the laboratory twice so a component of vari-
ance could be determined for the laboratory.
In Field 1, the plant cane crop had been removed for seed about three
weeks prior to sampling. The field had been planted with sweet corn followed
by celery before being planted with sugarcane. No fertilizer was applied to the
sugarcane because of the high residual fertility from the celery crop. In Field 2,
the first crop of cane had been removed about 2 weeks prior to sampling. The
field had been in pasture prior to being planted to cane. The cane received 600
pounds per acre of 0-6-45 fertilizer in the row at planting. In Field 3, the second
crop of cane had been removed just prior to sampling. This field also had been
in pasture before being planted to sugarcane. The plant cane received 600
pounds per acre of an 0-6-45 fertilizer in the row at planting. After the plant
cane was removed, a sidedressing of 300 pounds per acre of 0-6-45 was applied
in a band on either side of the row.
In order to determine a sampling plan, estimates of the variance compo-
nents were obtained. The components of interest were those due to (1) the
areas, (2) the rows within areas, and (3) laboratory determinations for each of
the five distances.
Using these estimates, a sampling plan was made using a fixed value of
the variance of y, and the grand mean [ V(y)]. First the optimum number of rows
(r), and determinations (d) were calculated as follows:
r = (o2-r a2) /2
d=(-d2 +r2)V
With the variance of the overall mean fixed, the optimum number of areas (a) to
be sampled was determined by the formula:
SAR (~ ra,2 + d 2 + Ud2)
r d (AR V(y) + R Ua2 + r'2)
where
A = total number of areas available for sampling (A = 396 for Field 1 and
702 for Fields 2 and 3;
V(y)= 100 for K, 4 for P, and 0.01 for pH; and
R = total number of rows within each area available for sampling
(R = 5).
To find how many samples to take from a field and composite into one
sample, the optimum number of rows (r) was multiplied by the optimum num-
ber of areas (a). Since the optimum number of determinations was less than 1 in
all but three instances, the optimum number was assumed as 1 (the number that
will be run on a grower's sample).








B. RESULTS AND DISCUSSION


1. STANDARD DEVIATIONS IN EXPERIMENTAL PLOTS
The standard deviations for samples taken prior to planting in 0.02-acre
plots (Table 6) were less than 0.5 units of soil test for P and less than 6 units for
K. The deviations for samples taken prior to ratooning were higher (0.4 to 1.7
for P and 12 to 68 for K). It should be emphasized that all fertilizer was uni-
formly broadcast over these areas and the small plots were intensively sampled
between the rows to a depth of 0 to 12 inches. The conclusion is that the poor
reliability of ratoon samples was the result of nutrient uptake patterns in the
proceeding crop. It is likely that the results would have been even less precise
had the plant cane fertilizer been banded or had the soil samples been collected
in, or close to, the rows.

2. DEPTH AND POSITION OF SAMPLING
Both depth and horizontal position with reference to the row have a large
influence on the soil-test values obtained. Samples taken within 12 inches of the
row resulted in about double the P soil test of samples taken between the rows in
a first ratoon field of commercial cane where the plant fertilizer was banded
(Table 7). The P test values decreased rapidly with depth. The results empha-
size the influence of residual P and the need for precision in the method of sam-
pling ratoon fields.

3. NUMBER OF SAMPLES NEEDED
In the third sampling study the number of samples needed to get a reason-
able estimate of the fertility of a field was determined (Table 8). Field 1 was
much more variable and required more samples in order to obtain an acceptable
estimate of fertility than did Fields 2 and 3. The minimum samples necessary


Table 6. Standard deviations of soil phosphorus and potassium for samples collected
prior to plant and ratoon crops.

Fertilization Soil Test P Soil Test K
Level Plant Rat. 1 tt Rat. 2 Plant Rat. I Rat. 2
Location 1
0 0.43 0.85 0.85 6 30 62
1 1.06 0.85 32 68
2 1.70 1.67 24 67
Location 2
0 0.46 0.64 0.43 6 19 20
1 0.72 0.74 12 16
2 0.60 0.93 15 14
3 0.88 1.13 17 17
4 0.79 1.67 14 18
tPlant cane samples were collected after the fields were prepared for planting but before
fertilization.
ttRatoon samples were collected following harvests and before any significant growth was made.








Table 7. Phosphorus soil test values at different sampling depths and locations in the row
in two ratoon fields.

Depth of P Soil Test
Sampling (in) Location of Sampling Field 1 Field 2 Mean
0 to 12 between rows 6 5 6
0 to 12 in rows 16 8 12
Oto 2 between rows 11 11 11
2 to 6 between rows 9 8 8
6 to 12 between rows 4 2 3



Table 8. Optimum number of samples needed to obtain a reasonable estimate of the
fertility of ratoon cane fields.

Distances from Center ofRow (in)
0 6 12 18 24
Field 1 t
pH 3 3 2 3 3
P 62 40 47 77 87
K ---tt 103 71 146 ---tt
Field 2 t
pH 4 5 4 3 3
P 23 6 6 4 2
K 78 ---tt 50 33 12
Field 3 t
pH 5 7 5 5 5
P 19 18 7 3 4
K 87 35 11 10 9
tField 1: one crop of cane removed with no fertilizer applied to the plant crop. Field 2: one crop
of cane removed with fertilizer applied in the row to the plant crop. Field 3: two crops of cane
removed with fertilizer applied in the row to the plant crop and side-dressed to the second crop.
ttThe mean square for among rows was greater than that due to areas, leading to negative esti-
mates of a22, which are meaningless.



were 87, 12, and 9 for fields 1, 2, and 3, respectively, for the 24-inch distance
from the row. More samples were required for samplings in or closer to the row.
In addition to the larger number of samples required in ratoon fields, the fertility
estimate obtained from 87 samples taken at the 24-inch distance does not neces-
sarily give the best correlation with yields. More samples taken closer to the
row may give a better correlation with yield which would be more desirable for
predicting fertilizer needs.
Variability among fields is large. Potassium is the element requiring the
most extensive sampling to obtain reliable estimates. The large variances and
the large number of core samples needed indicate that good sampling in existing
cane fields is not easy, if at all possible. The large number of cores required to








get reliable fertility estimates practically rules out the possibility that growers
can obtain good soil tests in cane fields except prior to planting, when the soil is
thoroughly mixed.


V. DETERMINATION OF FERTILIZER
RECOMMENDATIONS FOR PHOSPHORUS
AND POTASSIUM

A. EXPERIMENTAL PROCEDURES
Total sugar per acre for three years was compared by regression analysis
with total P2 05 applied per acre. A second-order regression equation, Y= a +
bX + cX2 (where Y= sugar yield per acre for three years, X=pounds of P2 05
applied in three crops; and a, b, and c are constants), was used to describe the
data. The P2 0 application required to obtain the maximum sugar yield was
calculated as the derivative of the regression equations.
Sugar yield per acre from both Locations 1 and 2 was converted to percent
of the maximum yield by selecting the P2 05 application at a given location
which produced the highest yield and equating the data for lower yields at that
location on a percentage basis. An optimum P2 05 application was then ob-
tained for the combined data by the same method as for the individual locations.
Consideration of only the points which described a positive response to
P2 0 in a linear regression equation with P2 0 applied provided the basis for
the P2 05 recommendation from soil test.
Recommendations for P at other before-planting soil tests were formula-
ted by assuming that 20 pounds of P2 05 equals 1 unit of P soil test by the AREC
method of extraction. Adjusting fertilizer recommendations for yield goals was
accomplished by adding or subtracting 2.2 pounds of P2 01 from the recom-
mendations for each change of 1 ton per acre in the yield goal based on calcula-
tions from the data of Andreis (1975).

B. RESULTS AND DISCUSSION
Responses to added P over a three-crop period were similar for two exper-
iments where the before-planting P soil test was 2 (Fig. 6). The significant qua-
dratic responses indicate maximum sugar per acre per year at 200 and 210
pounds per acre of P2 0, for the two experiments, respectively. The parallel
nature of the results from these experiments suggested that the data could be
combined and the measured tonnages of sugar for three harvests expressed as a
percentage of the maximum yield obtained in a given experiment. When the
two sets of data were combined, the quadratic response in Figure 8 was ob-
tained. Maximum tonnage of sugar per acre for three years was obtained when
202 pounds per acre of P2 05 was applied over the three-year period. Previous









LJ / --


4-

LL / Y=81.305+O.168X-O.0004X2, R=0.963 **
o /
0 /





/ Y=82.670+0.098X, R=0.961*









POUNDS OF P202/ACRE IN 3 YEARS
LL
0
I--
z 80

a.

0 100 200 300
POUNDS OF P205/ACRE IN 3 YEARS


Figure 8. Relative yields of the total amounts of sugar per acre produced in a crop cycle
for Locations 1 and 2 combined using a curvilinear equation to applied P for
all data points and a linear equation for points up to maximum sugar yield.
**Regressions are significant at the 0.01 level.
o denotes means of the eight rates for the two locations.


recommendations (Gascho and Freeman, 1974) would have provided a maxi-
mum of 100 pounds per acre of P2 05, resulting in 4.8 percent less sugar per
acre over the three-year period.
Since the points higher than 202 pounds per acre are of no practical im-
portance for predicting amounts of P2 05 required, they were dropped from
consideration. Using the revised set of data points, a significant linear regres-
sion was obtained for use in recommending fertilizer P from soil test (Fig. 8).
Sugarcane tonnage averaged 43 tons per acre in these experiments, and
the desired recommendation level was for a 40 tons per acre crop. The 40 ton
per acre per year line, indicating the effect of applied P versus soil test P (Fig.
9), was drawn by using the changes in soil P per unit of applied P found by
Forsee (1950), Forsee and Hoffman (1950) and Forsee et al. (1954). The corre-
lation of soil tests with applied P was not possible in this study because only one
before-planting soil test was studied (i.e., P = 2 for both locations). The re-
sponse of soil test to applied P was greatly different for the two locations, but
the yield responses were similar. More work is needed to correlate soil test with
applied P, and until that is accomplished, the values obtained by Forsee et al.








I I I I I I


50 TONS OF CANE/ACRE
U)

S200

Z 40 TONS OF CANE/ACRE
w
o


I0
0

100-

0
0.


30 TONS OF CANE/ACRE


0-
0 2 4 6 8 10 12 14

PHOSPHORUS SOIL TEST

Figure 9. Recommended rates of P to apply in a three-year crop cycle, as affected by
the AREC before-planting soil test, for three yield goals.


will be used. The 40 ton per acre per year line is the basis of the recommenda-
tions for fertilizer P. The 30 and 50-ton lines are given to provide growers with
a choice according to their individual goals and yield histories. It is noteworthy
that a grower with a history of growing only 25 to 30 tons per acre of cane could
not expect 50 tons per acre per year only by applying more fertilizer P.
Recommended rates of P2 05 applications for a given soil test prior to
planting are given in Table 9. The rates recommended should bring the P soil
test to ca 7 at the start of a crop where the beginning soil test is in a range of 4 to
7. In cases where the soil test is very low, two to three years or longer is allowed
to reach 7, as the recommendation never exceeds 75 pounds P2 05 per acre per
year because of the detrimental effects of excessive soluble P on sucrose con-
tent of sugarcane juice. Because of the possibilities of leaching of P in low pH
soil, and fixation in other soils, it is likely that soil-test P levels of 5 to 7 will not








Table 9. Phosphorus recommendations for a whole-cycle of sugarcane as a function
of AREC, Belle Glade, water-extractable phosphorus in before-planting
soil samples. A yield goal of 40 tons cane per acre per year is assumed.

Soil Test Crop Year
P Plant First ratoon Second ratoon Third ratoon
-------------------------- lb/acre P2 05 -----------
Trace 75 75 70 40
1 75 75 50 40
2 70 70 40 40
3 60 60 40 40
4 60 40 40 40
5 40 40 40 40
6 40 40 40 40
7 0 40 40 40
8 0 40 40 40
9 0 0 40 40
10 0 0 40 40
>10 0 0 0 40


always be reached. Forty pounds per acre of P2 05 is applied as a maintenance
level. This will usually raise the soil test from 5 to 7. After the growing of a 40-
ton per acre crop of sugarcane, the soil test would again be down to 5.
The percent-of-maximum-yield concept was also used for potassium cal-
ibrations (Fig. 10). The response of sugar per acre to added potassium was
small for a before-planting soil test of 40, due to reduced sugar concentration in
the cane for each additional potassium increment. The rates were therefore not
modified from the previous recommendations, they were only extended for a
whole-cycle recommendation (Table 10). About 2 pounds per acre of K2 0 is
required to raise the AREC soil test one unit. Potassium is required at a rate of


Table 10. Potassium recommendations for a whole-cycle of sugarcane as a function of
AREC, Belle Glade, one-half normal acetic-acid-extractable potassium in
before-planting soil samples.

Soil Test Crop Year
K Plant First ratoon Second ratoon Third ratoon
------- ------------------- lbacre K 0 ---------------------------
0-29 250 250 150 150
30-59 250 150 150 150
60-89 150 150 150 150
90-149 100 150 150 150
150-179 0 150 150 150
180-299 0 0 150 150
>299 0 0 0 150








100- -----

S* LOCATION I
S- LOCATION 2
S99
Cn
0
-I


S97


96- Y= 95.869+0.0036X, R=0.805**
U-
o
I.-
z
W 95
: 0 300 600 900 1200
Ca POUNDS OF K20/ACRE IN 3 YEARS

Figure 10. Relative yields of total sugar per acre over a three-crop cycle at both Loca-
tions 1 and 2 as affected by rate of K application.
**The regression is significant at the 0.01 level.


150 pounds per acre of K2 O equivalent for maintenance of a 40-ton per acre
crop (Bourne, 1956). A soil test of ca 150 is considered optimal at the start of a
crop. After a crop the soil test should be 50 to 75. In many cases, especially on
sandy soils, it is not possible to build up residual levels of potassium. Potassium
should then be applied each year to satisfy the nutritional requirements of that
year's crop.


VI. MAKING FERTILIZER
RECOMMENDATIONS
A Wang System 2200B desk-top computer has been programmed with
the tabular rates of P2 05 and K2 0 recommended for a given soil test (Tables 9
and 10) together with other recommendations not covered in this bulletin. Soil-
test results are systematically requested on the cathode-ray tube output. Upon
entry, the laboratory values are typed together with the recommendation on the
system typewriter output. An example of soil-test results and fertilizer recom-
mendations for the four soil textures tested at Belle Glade is given in Figure 11.
All recommendations are made on a pound of nutrient per acre basis. In
addition, the rate and grade of a high analysis fertilizer is given for each sample.
Nitrogen is recommended for sand and mucky sand (M/SA) soils. The
rates are 150 and 110 pounds N per acre per year in four applications with the













NAME: Sweet Farm Inc.
ADDRESS: P. 0. Box
South Bay FL
COUNTY: Palm Bear
----I----- ------
I I I
ILAB I FIELD I TEXT
INO. I I URE
I----I--------- I--


AC-F IC JLTI JRAL FE F.tA FC. H AiN ElI IC AT I iNi CR LITTER
i t 1 re -l i -<=y r-,i rLi y
P. Dr -awer A
Belle Glade, Florida
Res-ul ts and Rec rernnmendai ons

RECORD Nn.: POXXX
33493 REMARKS: This is a sample printout. NO. OF SAMPI ES: S
h COMPLETED:


I-----
I SOI.
I-----
I pH
I -----


----------------- I
TEST VALUES I
----------------I__
P K Ca Mg I
-----------------I,


----------I
I
CROP I
I
----------I.


8t A E MUCK 6.8 7 54 PLANT CANE
1st Ratoon
2nd Ratoon
3rd Ratoon
87 A 7 MUCK 5.3 2 102 PLANT CANE
Ist Ratoon
End Raltln
3rd Ratoon
88 A 8 S/MU S.5 1 E. 3040 334 PLANT CANE
1ot Ratonn
2nd Ratoon
3rd Paloorn


90 C 16


M/SA 7.2 0 32 SOOO RF. PL


RECOMMENDED: POUNDS PER ACRE
------------------------------.


N P205 kPO Mg Cu

O P20 0 P
) 40 150
0 40 150
1 40 150
) 70 100 0 2
1 70 150
1 40 150
) 40 150
1 75 150 0 P
) 75 10
) 50 150
) 40 ) 50


Mn 7n B LI

5.0 2 1.0



0.0 a 1.0



0.0 2 1.0


ME

0






0


ANI CANE 1i 7S ROO F 1i 0.0 1 0.5 3coC
Initial app li atinr
Stddreod t times with
ist RATOON 150 75 20O
Initial application
S-iddrers 3 +tmes with
2nd RATOnN ISO rO 10S
Initial applic-tion
Sidedress 3 times with
3rd RATOON 150 40 10O
initial ppl i c-tion
Sidedress 3 +imes with
ANT CANE 110 7S PSO 6 1 P.5 1 0.5 0
Initial application
Sidedress 3 times with
1st RATOON 110 75 150
Initial appjoliatio
Sidedr-rs I times with
End RATOON 110 70 150
Initial applictinn
Sirded-es 3 times with
3rd RATOON 110 40 ISO
Initial application
S ,dedress 3 time, wi th


I----I----- I------I------------------- I----------- I ---------- --------- --..
* May be too little for practical ground rig application.
NOTE: SULFUR (S) here is for pH correction only. Apply in furrow at planting with fertilizer. DO NOT hroadcas


--- --------------- I
I POS-IB E FERT I
---- I ------------ I
SLLFUR I Lb/A CGADE T
------------------ I
500 5o00 o O s
O 350 0 1; 3
ISO On 1 3
350 0 1! 43
350 0 11 O3
0 AO 0 17 37
400 0 17 37

350 0 11'
0 500 0 1I
450 0 17 33
350 0 P l 0 1
350 0 11 43


ISO 15 O 5 2
S00 11 I s 16

200 !0 0 25
-500 12 15 rI
I00 is POa

400 15 12 15
150 BO 0 20

400 15 10 15
1O UM O 20
300
500 9 15 l B
150 15 O 33

.i00 11 1? 15
100 P22 0 21

400 11 17 15
100 22 0 ?1

350 13 11 17
100 22 0 21
__ -_-_

st sulfur.


Figure 11. Sample soil test results and sugarcane fertilization recommendations.


C 14 SAND 4.8 1 19 R L








Table 11. English to metric conversion factors.

1. tons/acre x 2.24 = metric tons/hectare
2. tons x 0.907 = metric tons
3. acres x 0.405 = hectares
4. pounds/acre x 1.12 = kilograms/hectare
5. feet x 0.305 = meters
6. pounds x 0.454 = kilograms


K2 O for sand and M/SA, respectively. Sulfur is recommended as a furrow ap-
plication together with micronutrients in plant cane where the soil pH is 6.5 or
greater. The rates are 500 pounds per acre for muck and sandy muck (S/MU)
and 300 pounds per acre for sand and M/SA.
Magnesium is recommended at 6 pounds per acre on muck and sandy
muck when the soil test is less than 100. Lime, usually dolomite, is recommen-
ded at 1.5 tons per acre before planting on M/SA and 1.0 ton per acre on sand
where the pH is less than 5.
Because of the dramatic responses to micronutrients in the history of the
Everglades farming, micronutrients are still recommended for plant cane even
though no good soil tests are available. Copper and zinc are recommended for
plant cane at 2.0 pounds per acre for muck and S/MU and at 1.0 pound per acre
for sand and M/SA. Boron is recommended at a rate of 1.0 pound per acre on all
plant cane. Manganese is recommended as a furrow application in plant cane
when the soil pH is 6.0 or greater. The rates are 5.0 pounds per acre for muck
and S/MU and 2.0 pounds per acre for sand and M/SA. There is little doubt that
some excessive applications of micronutrients are made (Andreis, 1975).
Growers are urged to tissue test their final ratoon before replanting in order to
gauge the need for more micronutrients in the next plant crop.


VII. SUMMARY
1. Phosphorus recommendations for sugarcane from the AREC, Belle
Glade, have been increased and should increase sugar production by 4 to 5 per-
cent above levels where earlier recommendations were followed. In addition,
the higher levels of P should extend the life of a given planting due to mainte-
nance of a better ratoon stand. Additional research is needed to determine the
best way to split P applications among the plant and ratoon crops within a cycle
and to check the recommendations at more locations with a wide range of P soil-
test levels.
2. Responses to K were very modest. Increases in the tonnages of cane
per acre were nearly nullified in terms of sugar per acre due to the decreasing
sucrose content with higher rates of K. This result is contrary to the generally
accepted findings that K increases juice quality.









3. Sampling and testing soils only prior to planting should result in the
analysis of samples which are more representative. This change will increase
the reliability of the recommendations as well as save time for the grower, the
soil-testing laboratory, and extension personnel. Recommendations made for a
whole-cycle also allow the grower more time to plan and budget fertilizer pur-
chases.



VIII. REFERENCES

1. Allison, R. V. 1932. Soil fertility investigations. Univ. Fla. Agr. Exp. Sta. Ann.
Rep. pp. 187-189.
2. Analytical Methods for Atomic Absorbtion Spectrophotometry. Perkin Elmer
Corp., Norwalk, Conn.
3. Andreis, H. J. 1975. Macro and micronutrient content of millable sugarcane grown
on organic soils in Florida. Sugar J. 37(8):10-12.
4. Arceneaux, G. 1935. A simplified method of making sugar calculations in accord-
ance with the Winter-Carp-Geerlig's formula. Int. Sugar J. 37:264-265.
5. Barnes, A. C. 1974. The Sugar Cane. John Wiley and Sons, N.Y., N.Y.
6. Bourne, B. A. 1950. Physiological effects of soil phosphorus deficiency and excess
on sugar cane on low-mineral peat soil. Proc. 7th Cong. Int. Soc. Sugar Cane
Technol. pp. 233-242.
7. Bourne, B. A. 1956. Sugarcane cultivation throughout the world. IN The Handbook
of Sugarcane, edited by C. van Dillewijn. The Chronica Botanica Co., Waltham,
Mass.
8. Forsee, W. T., Jr. 1950. The place of soil and tissue testing in evaluating fertility
levels under Everglades conditions. Soil Sci. Soc. Amer. Proc. 15:297-299.
9. Forsee, W. T., Jr., V. E. Green, Jr., and R. H. Webster. 1954. Fertilizer experi-
ments with field corn on Everglades peaty muck soil. Soil Sci. Soc. Amer. Proc.
18:76-79.
10. Forsee, W. T., Jr., and J. C. Hoffman. 1950. The phosphate and potash require-
ments of snap beans on the organic soils of the Florida Everglades. Proc. Amer.
Soc. Hort. Sci. 56:261-265.
11. Gascho, G. J., and C. E. Freeman. 1974. Fertilizer recommendations for sugarcane.
Belle Glade AREC Res. Rep. EV-1974-18.
12. Gee, A., and V. R. Deitz. 1953. Determination of phosphate by differential spectro-
photometry. Anal. Chem. 25:1320-1324.
13. Gieseking, J. E., H. J. Snider, and C. A. Getz. 1935. Destruction of organic matter
in plant material by the use of nitric and perchloric acids. Ind. and Eng. Chem.
7:185-186.
14. Iley, J. R. and F. le Grand. 1964. Sugarcane fertility. Soil and Crop Sci. Soc. Fla.,
Proc. 24:430-435.
15. Iley, J. R., F. le Grand, and C. C. Hortenstine. 1965. Some factors affecting the
phosphorus content of leaf tissue from sugarcane grown on organic soils. Proc.
12th Cong. Int. Soc. Sugar Cane Technol. pp. 237-243.









16. le Grand, F., H. W. Burdine, and F. H. Thomas. 1961. Phosphorus and potassium
requirements for growing sugarcane on organic soils in south Florida. Sugar J.
24:(1)22-26.
17. le Grand, F., and F. H. Thomas. 1963. Influence of phosphorus and sulfur applica-
tions on the growth and chemical analysis of sugarcane growing on organic soils.
Everglades Sta. Mimeo Rep. EES 64-13.
18. Neller, J. R. 1942. A comparison of different sources of phosphorus for use on
Everglades peat. Soil Sci. Soc. Fla., Proc. IV-B:55-60.
19. Neller, J. R. 1945. Availability of the phosphorus of various types of phosphates
added to Everglades peat land. Univ. Fla. Agr. Exp. Sta. Bull. No. 408.
20. Rice, E. R., and L. P. Hebert. 1971. Sugarcane variety tests in Florida, 1970-71
season. ARS, USDA publication ARS 34-127.
21. Spencer, G. L., and G. P. Meade. 1945. Cane Sugar Handbook. John Wiley and
Sons, Inc., New York, N.Y.
22. Stevens, F. D. 1945. Fla. Agr. Exp. Sta. Ann. Rept. p. 207.
23. Thomas, F. H. 1965. Sampling and methods used for analysis of soils in the soil
testing laboratory of the Everglades Experiment Station. Everglades Sta. Mimeo
Rep. EES 65-18.





MA! 2 1 3 '






































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HISTORIC NOTE


The publications in this collection do
not reflect current scientific knowledge
or recommendations. These texts
represent the historic publishing
record of the Institute for Food and
Agricultural Sciences and should be
used only to trace the historic work of
the Institute and its staff. Current IFAS
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