• TABLE OF CONTENTS
HIDE
 Copyright
 Front Cover
 Title Page
 Table of Contents
 Preface
 The extension soil testing...
 Description of tests offered
 Lime requirement and fertilizer...
 Electrical conductivity interp...
 Interpretation of water-test...
 Interpretation of container media...
 Reference






Group Title: Circular - Florida Cooperative Extension Service - 817
Title: Soil, container media, and water testing
CITATION PDF VIEWER PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00056170/00001
 Material Information
Title: Soil, container media, and water testing interpretations and IFAS standardized fertilization recommendations
Series Title: Circular
Alternate Title: Interpretations and IFAS standardized fertilization recommendations
Physical Description: vi, 49 p. : ill. ; 28 cm.
Language: English
Creator: Hanlon, Edward A ( Edward Aloysius ), 1946-
Kidder, Gerald, 1940-
McNeal, Brian Lester, 1938-
Publisher: Florida Cooperative Extension Service, Florida Cooperative Extension Service, Institute of Food and Agricultural Sciences
Place of Publication: Gainesville Fla
Publication Date: 1990
 Subjects
Subject: Fertilizers -- Research -- Florida   ( lcsh )
Soils -- Testing -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Includes bibliographical references (p. 49).
Statement of Responsibility: E. A. Hanlon, G. Kidder, and B.L. McNeal.
General Note: "March 1990."
Funding: Circular (Florida Cooperative Extension Service) ;
 Record Information
Bibliographic ID: UF00056170
Volume ID: VID00001
Source Institution: Marston Science Library, George A. Smathers Libraries, University of Florida
Holding Location: Florida Agricultural Experiment Station, Florida Cooperative Extension Service, Florida Department of Agriculture and Consumer Services, and the Engineering and Industrial Experiment Station; Institute for Food and Agricultural Services (IFAS), University of Florida
Rights Management: All rights reserved, Board of Trustees of the University of Florida
Resource Identifier: oclc - 70278150

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Table of Contents
    Copyright
        Copyright
    Front Cover
        Page i
    Title Page
        Page ii
    Table of Contents
        Page iii
        Page iv
        Page v
    Preface
        Page vi
    The extension soil testing laboratory
        Page 1
        Introduction
            Page 1
        Operating directive of the ESTL
            Page 1
        Why do we fertilize?
            Page 1
        Soil sampling variability
            Page 2
        Nutrient mobility - Types of soil sampling
            Page 3
            Page 4
        Soil test calibration
            Page 5
            Page 6
            Page 7
            Page 8
    Description of tests offered
        Page 9
        Commercial production of agronomic crops, forages, and vegetables
            Page 9
        Landscape and vegetable garden test
            Page 10
        Forest and forest nursery soil tests
            Page 10
        Container media test
            Page 10
        How to submit samples to the ESTL
            Page 11
            Page 12
    Lime requirement and fertilizer recommendations
        Page 13
        Lime requirement
            Page 13
            Page 14
        Table 1: Soil pH and liming footnotes
            Page 15
        Fertilizer tables
            Page 16
            Page 17
            Page 18
            Page 19
            Page 20
            Page 21
            Page 22
            Page 23
            Page 24
            Page 25
            Page 26
            Page 27
            Page 28
            Page 29
            Page 30
            Page 31
            Page 32
            Page 33
            Page 34
    Electrical conductivity interpretations
        Page 35
        Modification for soils containing gypsum or lime - Inter-conversion from former soluble salt values
            Page 36
        Assumptions and mode of calculation
            Page 35
        Salt-index ranges for selected commodities
            Page 37
            Page 38
            Page 39
            Page 40
            Page 41
            Page 42
            Page 43
            Page 44
    Interpretation of water-test results
        Page 45
        Household uses
            Page 45
            Page 46
    Interpretation of container media test results
        Page 47
        Uses for the container media test
            Page 47
        Interpretation of results
            Page 47
            Page 48
    Reference
        Page 49
Full Text





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
research may be found on the
Electronic Data Information Source
(EDIS)

site maintained by the Florida
Cooperative Extension Service.






Copyright 2005, Board of Trustees, University
of Florida












Soil, Container Media, and Water Testing



Interpretations and IFAS Standardized
Fertilization Recommendations





E.A. Hanlon, G. Kidder, and B.L. McNeal'


Florida Cooperative Extension Service
Institute of Food and Agricultural Sciences
University of Florida, Gainesville
John T. Woeste, Dean for Extension


March 1990


Circular 817


"
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4:r









Soil, Container Media, and Water Testing


Interpretations and IFAS Standardized
Fertilization Recommendations





E.A. Hanlon, G. Kidder, and B.L. McNeal'




















The authors wish to express their thanks to Dr. R. D. Rhue for his efforts when he served
as Director of the Extension Soil Testing Laboratory. His direction and leadership
contributed greatly to the scientific foundation of this laboratory.

The updated interpretations and recommendations found in this publication represent the
work of many extension specialists and are a result of an IFAS-wide effort to present the
most current information to Florida's public. The authors wish to thank G. J. Hochmuth,
T. H. Yeager, and C. L. Chambliss for the extra effort which they offered freely to improve
the accuracy and timeliness of this publication.


* E. A. Hanlon is Associate Professor, Extension Soil Management Specialist, and Director
of the Extension Soil Testing Laboratory; G. Kidder is Professor and Extension Soils
Specialist; and B.L. McNeal is Professor of Soil Science; IFAS, University of Florida,
Gainesville.










Table of Contents
Page

Preface ............... .................... ................ vi

Section 1
The Extension Soil Testing Laboratory

Introduction ................................................... 1
Operating Directive of the ESTL ..................... ............. 1
W hy Do W e Fertilize? ................ ......................... 1
Soil Sampling Variability ......................................... 2
Nutrient M obility .............................................. 3
Types of Soil Sampling ................ .......................... 3
Predictive Soil Sampling ................ ....................... 3
Diagnostic Soil Sampling ................ ...................... .3

Soil-Test Calibration ................ ............................ 5
The Calibration Process ....................................... 5
Interpretation of Soil-Test Values ................. ............... 7
Recommendations based upon Soil Testing .................. ........ 8

Section 2
Description of Tests Offered

W hat Tests are Offered .......................................... 9
Commercial Production of Agronomic Crops,
Forages, and Vegetables ................ ...................... 9
Landscape and Vegetable Garden Test ................. ........ 10
Forest and Forest Nursery Soil Tests .................. ........... 10
Container Media Test ......................................... 10
W after Test ................ ............................. 11

How to Submit Your Samples to the ESTL ............................ 11
Soil Samples ................. ............................. 11
W ater Samples .......................................... 11
Methods of Sample Delivery to the ESTL ........................... 12

Section 3
Lime Requirement and Fertilizer Recommendations

-- Lime --

Lime Requirement ........................................... 13

Table 1. Soil pH and liming footnotes .................. .......... 15

-- Fertilizer Tables --

IFAS Standardized Fertilizer Recommendations ...................... 16









Table 2. Current Mehlich-I soil-test interpretations used in the
IFAS-wide Standardized Fertilizer
Recommendation System ............................. 18

Table 3. IFAS standardized fertilizer recommendation
for magnesium, all crops ............................. 18

Table 4. Target pH, and recommended N, P205, and K20 fertilizer
rates for agronomic crops ............................. 19

Table 5. Applicable footnote numbers and additional reading
for agronomic crops ............................... 20

Table 6. Target pH, and recommended N, P2Os, and K20 fertilizer
rates for commercial vegetable production ................. 21

Table 7. Applicable footnote numbers and additional reading
for commercial vegetable production ................. ... 22

Table 8. Target pH for citrus and blueberry production .............. 23

Table 9. Applicable footnotes and additional reading
for citrus and blueberry production ......... .... ..... .. 23

Table 10. Target pH, and recommended N, P205, and KIO fertilizer
rates for turfgrass production and lawns .................. 24

Table 11. Applicable footnotes and additional reading
for turfgrass production and lawns ....................... 25

Table 12. Target pH, and recommended N, P205, and Kf2 fertilizer
rates for ornamentals in commercial production and
ornamentals in the landscape ............... ......... 26

Table 13. Applicable footnote numbers and additional reading
for ornamentals in commercial production and
ornamentals in the landscape ......................... 27

Table 14a. Footnotes used with agronomic crops .................. .. 28

Table 14b. Footnotes used with vegetable crops ...................... 31

Table 14c. Footnotes used with citrus and blueberries ................. 32

Table 14d. Footnotes used with turfgrasses ....................... 32

Table 14e. Footnotes used with ornamentals in
commercial production and
ornamentals in the landscape ......................... 33








Table 14f. Footnotes used with commercial forestry production .......... 33

Table 14g. Footnotes used with landscapes, lawns, and vegetable gardens .... 34

Section 4
Electrical Conductivity Interpretations

Assumptions and Mode of Calculation ............................ 35
Modification for Soils Containing Gypsum or Lime .................... 36
Inter-conversion from Former Soluble Salt Values ..................... 36
Salt-Index Ranges for Selected Commodities ......................... 37

Table 15. Relative yields of selected field and forage
crops at selected salt-index levels ...................... 38

Table 16. Relative yields of selected vegetable crops
at selected salt-index values ........................... 40

Table 17. Relative yields of selected fruit crops
at selected salt-index values .......................... 41

Table 18. Relative yields of selected ornamentals
at selected salt-index values ........................... 42

Section 5
Interpretation of Water-Test Results

Household Uses ............................................. 45

Table 19. Interpretation for the hardness scale for
household water .................. ................. 45

Table 20. Classification of irrigation water in terms of
electrical conductivity .................. ............. 46

Section 6
Interpretation of Container Media Test

Uses for the Container Media Test ............................... 47
Interpretation of Results ...................................... 47

Table 21. Interpretation of container media test for
woody ornamentals ................................. 48

Table 22. Interpretation of container media test for
bedding and pot plants .............................. 48

Section 7

Literature Cited ................. .............................. 49








--- Purpose of This Manual and Intended Audience ---

This manual has been compiled for the purpose of providing a single reference source
for information regarding interpretations of test results and fertilizer recommendations
issued by the University of Florida, Institute of Food and Agricultural Sciences, Extension
Soil Testing Laboratory (ESTL). The manual contains two divisions: 1) concepts of soil
testing for fertilizer recommendations, and 2) a description of fertilization recommenda-
tions by commodity and type of test.

The first division explains the role that soil-fertility testing should play with respect to
fertilizer use. Each of the tests offered by the ESTL is described, as well as the proper
method of sample collection and handling.

The second division contains the current interpretations and fertilizer recommendations
which comprise the IFAS Standardized Fertilizer Recommendations. These recommenda-
tions are under constant review and updated as needed; however, this publication should
serve as a bench mark to indicate our current understanding. This review process involves
over 200 IFAS faculty state-wide, both from commodity departments as well as the Soil
Science Department to insure that these recommendations are reliable and practical.

Soil testing should be used as a tool to assist in making fertilizer management decisions.
Proper use of fertilizers based upon soil testing works best when all management decisions
are made wisely and all other production limitations are considered.

The IFAS Standardized Fertilizer Recommendations include not only information
regarding the amounts of fertilizer but information on how to manage the fertilizer to
obtain optimum yields while minimizing both production costs and possible environmental
impact.








--- SECTION 1 ---


Introduction

The Institute of Food and Agricultural Sciences Extension Soil Testing Laboratory
(ESTL) was established to serve the people of Florida by using soil and water testing as a
vehicle to distribute current information regarding appropriate use of fertilizers and
fertilizer-management techniques in the state.

Operating Directive of the ESTL

As part of the Soil Science Department of the Institute of Food and Agricultural
Sciences (IFAS), the ESTL serves two primary functions:

1) to serve citizens of Florida, including growers, homeowners, and other interested
parties, by providing specific, agriculturally-related soil and water testing through the
Cooperative Extension Service, and

2) to provide analytical services needed to support research and extension field
demonstrations involving proper management techniques and improved soil-testing
procedures for efficient fertilizer use.

The ESTL provides chemical analyses of mineral and organic soils, container media,
certain plant-tissue analyses, and irrigation and household water samples for Florida
residents. Requests for testing of such materials as sewage sludges, wastewater effluent,
sludges from water-treatment facilities, fertilizers, soil amendments, or limestone are
referred to other governmental or private laboratories. Soil testing procedures for calcareous
Florida soils, such as the marl and rockland soils of southeast Florida, have not yet been
calibrated to crop response according to existing research literature. Therefore, the ESTL
offers no testing of such soils.

Why Do We Fertilize?

To use soil testing and the resulting recommendations effectively, one must understand
that fertilizer should be used to supply only that portion of the so-called crop-nutrient
requirement which cannot be supplied from the soil. Fertilizer is applied to the soil, not
to increase soil-test levels, but to improve plant nutrition. Without a positive crop response
to this added nutrition, there is little incentive to add fertilizer to the soil. A crop can only
produce its maximum yield (for a given set-of environmental conditions) when plant-availa-
ble nutrition, from both soil and added fertilizers, satisfies the crop-nutrient requirement.

For instance, some homeowners desire a thick, green lawn. If the lawn becomes pale
green and ceases to grow vigorously, and the need for nitrogen (N) is indicated, the
homeowner should add N fertilizer to improve the vigor of his grass. In this case, the
desired crop response is a green lawn. However, a commercial producer of corn, for
example, should not add fertilizer that simply results in greener corn plants, if there is no
resultant increase in marketable corn yields.

The soil may already contain enough of each of the essential plant nutrients (from
previous cropping, from previous fertilizer and lime additions, or from minerals found
naturally in the soil, etc.), to supply all needed nutrients for optimum crop growth. At








--- SECTION 1 ---


Introduction

The Institute of Food and Agricultural Sciences Extension Soil Testing Laboratory
(ESTL) was established to serve the people of Florida by using soil and water testing as a
vehicle to distribute current information regarding appropriate use of fertilizers and
fertilizer-management techniques in the state.

Operating Directive of the ESTL

As part of the Soil Science Department of the Institute of Food and Agricultural
Sciences (IFAS), the ESTL serves two primary functions:

1) to serve citizens of Florida, including growers, homeowners, and other interested
parties, by providing specific, agriculturally-related soil and water testing through the
Cooperative Extension Service, and

2) to provide analytical services needed to support research and extension field
demonstrations involving proper management techniques and improved soil-testing
procedures for efficient fertilizer use.

The ESTL provides chemical analyses of mineral and organic soils, container media,
certain plant-tissue analyses, and irrigation and household water samples for Florida
residents. Requests for testing of such materials as sewage sludges, wastewater effluent,
sludges from water-treatment facilities, fertilizers, soil amendments, or limestone are
referred to other governmental or private laboratories. Soil testing procedures for calcareous
Florida soils, such as the marl and rockland soils of southeast Florida, have not yet been
calibrated to crop response according to existing research literature. Therefore, the ESTL
offers no testing of such soils.

Why Do We Fertilize?

To use soil testing and the resulting recommendations effectively, one must understand
that fertilizer should be used to supply only that portion of the so-called crop-nutrient
requirement which cannot be supplied from the soil. Fertilizer is applied to the soil, not
to increase soil-test levels, but to improve plant nutrition. Without a positive crop response
to this added nutrition, there is little incentive to add fertilizer to the soil. A crop can only
produce its maximum yield (for a given set-of environmental conditions) when plant-availa-
ble nutrition, from both soil and added fertilizers, satisfies the crop-nutrient requirement.

For instance, some homeowners desire a thick, green lawn. If the lawn becomes pale
green and ceases to grow vigorously, and the need for nitrogen (N) is indicated, the
homeowner should add N fertilizer to improve the vigor of his grass. In this case, the
desired crop response is a green lawn. However, a commercial producer of corn, for
example, should not add fertilizer that simply results in greener corn plants, if there is no
resultant increase in marketable corn yields.

The soil may already contain enough of each of the essential plant nutrients (from
previous cropping, from previous fertilizer and lime additions, or from minerals found
naturally in the soil, etc.), to supply all needed nutrients for optimum crop growth. At








--- SECTION 1 ---


Introduction

The Institute of Food and Agricultural Sciences Extension Soil Testing Laboratory
(ESTL) was established to serve the people of Florida by using soil and water testing as a
vehicle to distribute current information regarding appropriate use of fertilizers and
fertilizer-management techniques in the state.

Operating Directive of the ESTL

As part of the Soil Science Department of the Institute of Food and Agricultural
Sciences (IFAS), the ESTL serves two primary functions:

1) to serve citizens of Florida, including growers, homeowners, and other interested
parties, by providing specific, agriculturally-related soil and water testing through the
Cooperative Extension Service, and

2) to provide analytical services needed to support research and extension field
demonstrations involving proper management techniques and improved soil-testing
procedures for efficient fertilizer use.

The ESTL provides chemical analyses of mineral and organic soils, container media,
certain plant-tissue analyses, and irrigation and household water samples for Florida
residents. Requests for testing of such materials as sewage sludges, wastewater effluent,
sludges from water-treatment facilities, fertilizers, soil amendments, or limestone are
referred to other governmental or private laboratories. Soil testing procedures for calcareous
Florida soils, such as the marl and rockland soils of southeast Florida, have not yet been
calibrated to crop response according to existing research literature. Therefore, the ESTL
offers no testing of such soils.

Why Do We Fertilize?

To use soil testing and the resulting recommendations effectively, one must understand
that fertilizer should be used to supply only that portion of the so-called crop-nutrient
requirement which cannot be supplied from the soil. Fertilizer is applied to the soil, not
to increase soil-test levels, but to improve plant nutrition. Without a positive crop response
to this added nutrition, there is little incentive to add fertilizer to the soil. A crop can only
produce its maximum yield (for a given set-of environmental conditions) when plant-availa-
ble nutrition, from both soil and added fertilizers, satisfies the crop-nutrient requirement.

For instance, some homeowners desire a thick, green lawn. If the lawn becomes pale
green and ceases to grow vigorously, and the need for nitrogen (N) is indicated, the
homeowner should add N fertilizer to improve the vigor of his grass. In this case, the
desired crop response is a green lawn. However, a commercial producer of corn, for
example, should not add fertilizer that simply results in greener corn plants, if there is no
resultant increase in marketable corn yields.

The soil may already contain enough of each of the essential plant nutrients (from
previous cropping, from previous fertilizer and lime additions, or from minerals found
naturally in the soil, etc.), to supply all needed nutrients for optimum crop growth. At








--- SECTION 1 ---


Introduction

The Institute of Food and Agricultural Sciences Extension Soil Testing Laboratory
(ESTL) was established to serve the people of Florida by using soil and water testing as a
vehicle to distribute current information regarding appropriate use of fertilizers and
fertilizer-management techniques in the state.

Operating Directive of the ESTL

As part of the Soil Science Department of the Institute of Food and Agricultural
Sciences (IFAS), the ESTL serves two primary functions:

1) to serve citizens of Florida, including growers, homeowners, and other interested
parties, by providing specific, agriculturally-related soil and water testing through the
Cooperative Extension Service, and

2) to provide analytical services needed to support research and extension field
demonstrations involving proper management techniques and improved soil-testing
procedures for efficient fertilizer use.

The ESTL provides chemical analyses of mineral and organic soils, container media,
certain plant-tissue analyses, and irrigation and household water samples for Florida
residents. Requests for testing of such materials as sewage sludges, wastewater effluent,
sludges from water-treatment facilities, fertilizers, soil amendments, or limestone are
referred to other governmental or private laboratories. Soil testing procedures for calcareous
Florida soils, such as the marl and rockland soils of southeast Florida, have not yet been
calibrated to crop response according to existing research literature. Therefore, the ESTL
offers no testing of such soils.

Why Do We Fertilize?

To use soil testing and the resulting recommendations effectively, one must understand
that fertilizer should be used to supply only that portion of the so-called crop-nutrient
requirement which cannot be supplied from the soil. Fertilizer is applied to the soil, not
to increase soil-test levels, but to improve plant nutrition. Without a positive crop response
to this added nutrition, there is little incentive to add fertilizer to the soil. A crop can only
produce its maximum yield (for a given set-of environmental conditions) when plant-availa-
ble nutrition, from both soil and added fertilizers, satisfies the crop-nutrient requirement.

For instance, some homeowners desire a thick, green lawn. If the lawn becomes pale
green and ceases to grow vigorously, and the need for nitrogen (N) is indicated, the
homeowner should add N fertilizer to improve the vigor of his grass. In this case, the
desired crop response is a green lawn. However, a commercial producer of corn, for
example, should not add fertilizer that simply results in greener corn plants, if there is no
resultant increase in marketable corn yields.

The soil may already contain enough of each of the essential plant nutrients (from
previous cropping, from previous fertilizer and lime additions, or from minerals found
naturally in the soil, etc.), to supply all needed nutrients for optimum crop growth. At








other times, however, the soil may be low in one or more essential nutrients (leached due
to rainfall, used by previous crops, etc.), and fertilizers or lime will be needed to produce
optimum plant response. The nutrient status of the soil can be estimated though soil
testing techniques which have been demonstrated to relate fertilizer additions to positive
crop response.

Here are several of the benefits achieved by using a proper soil testing and fertilization
system:

1. The crop is exposed to adequate, but not excessive, fertility. This condition permits
an excellent chance of achieving optimum growth without wasting fertilizer resources and
dollars or polluting the environment.

2. Because both soil fertility and fertilizers are used to satisfy the crop-nutrient
requirement, only that fertilizer which is actually needed to satisfy plant nutrition is ever
added to the soil.

3. Since fertilizers are added to the soil in amounts appropriate to optimize growth
response, no damaging fertilizer salts are present to slow plant development.

Soil Sampling Variability

The chemical and physical parameters of a soil vary from site to site. This inherent
variability directly affects the resulting fertilizer recommendation. In fact, most of the
variability in soil testing comes from the soil sampling process. Little error originates
within a well-run soil testing facility, due to quality-control procedures. Therefore, sampling
errors should be minimized to obtain a representative soil sample from the management
unit in question.

For commercial producers, the best way to sample an area is to partition the acreage
into management units, i.e., blocks of land which should be managed differently. This
partitioning should take into account such parameters as slope, soil type, soil fertility,
cropping patterns, and drainage. Some fields require high levels of management to be
productive, while others require much less management input. Each management unit
should be sampled separately.

From 15 to 20 soil cores should be taken from throughout the management unit. These
cores should be taken at random and mixed in a clean plastic bucket. The actual sample
sent to the ESTL should be taken from this mixed, composite soil.

Within any management unit, there may be small areas that represent problem sites.
Such areas may have chronic production problems, require different tillage techniques, or
be poorly drained. These problem sites should be sampled separately. Remember that the
goal is to obtain a soil sample that accurately represents the management unit. Problem
areas do not represent the entire management unit and should not be included in the
composite sample.

Homeowners and gardeners should consider their lawn as a management unit, while
their vegetable garden as another management unit. Plants growing in the landscape vary
widely in their liming and nutrient requirements. Consult the Landscape and Vegetable








Garden Information Form which shows species of similar needs and contains detailed
information on soil sampling procedures.

Nutrient Mobility

The mobility of a nutrient within the soil is critical to the value of soil testing. For
example, consider a mobile nutrient, such as nitrate. If a soil test for nitrate were made,
that test might measure reliably the quantity of nitrate in the soil at the time of sampling.
This quantity can change rapidly with rainfall, when some nitrate might be leached from
the soil profile. Such leaching would dramatically change the quantity of nitrate available
for plant use. Thus, nitrate soil testing is somewhat like taking a snap-shot of traffic at a
busy intersection. You can count the cars in the picture at any one instant in time, but
the movement of cars changes with time. Therefore, soil testing for mobile nutrients as a
basis for making fertilizer recommendations at the beginning of a growing season is of little
value under Florida's conditions of high rainfall and sandy soils.

On the other hand, immobile nutrients tend to remain in the soil profile. Such
nutrients, including phosphorus (P) and to a lesser extent potassium (K) (in sands), are
retained by various physical and chemical means on surfaces within the soil, thereby
resisting movement by leaching. Soil-test values obtained for immobile nutrients can be
linked to crop response and, therefore, to a fertilizer recommendation.

Types of Soil Sampling

Soil sampling can be divided conveniently into two distinct types, predictive soil
sampling and diagnostic soil sampling.

Predictive Soil Sampling

Those soil samples taken prior to planting a crop should be considered as predictive
samples. Predictive soil sampling is the most common type of soil sampling. To represent
best the fertility status of the soil in the management unit, the sample should be taken no
more than 4 to 6 weeks prior to planting. With proper calibration of the soil test, the
contribution to the crop-nutrient requirement from the soil for that particular immobile
nutrient is estimated. It is from this soil sample that a prediction of crop-fertilization needs
is made for the coming growing season.

Research has been reported throughout Florida to support predictive soil testing using
many commodities and cropping systems. Such sampling and testing continues to be an
excellent management tool.

Diagnostic Soil Sampling

Soil samples which are taken while the crop is actively growing should be considered
as diagnostic soil samples. Such testing may be used to monitor soil-nutrient status to
insure adequate nutrient supply to the plant. Monitoring can be of value for both immobile
nutrients and mobile nutrients, since one wants to know the nutrient status at the time of
sampling (i.e., a "snap shot") and is not interested in predicting the supply of soil-supplied
nutrients for the entire growing season.








The reasons for poor plant growth can be myriad, but, for some reason, nutritional
problems are often the first culprits considered. Data are sparse concerning the use of soil
testing for diagnostic purposes. Only when diagnostic soil-test results are combined with
other diagnostic clues can a proper interpretation be made by an experienced agronomist
or horticulturist. Other needed parts of the diagnostic puzzle include:

Stage of crop growth
Soil-test results from an appropriate extraction solution
Tissue samples from the proper plant parts)
Complete fertilizer, prior cropping, and pesticide records
Weather records
Pest scouting
Experience.

Soil sampling by itself rarely provides enough information additional diagnostic
information is needed as well.








Soil-Test Calibration


The fundamental process which makes soil testing meaningful for fertilizer recommenda-
tions is calibration. A particular soil test is calibrated by relating preplant soil-test values
to crop response to added fertilizer. For example, if a calibrated soil test indicates that the
soil is low in a particular immobile nutrient, then there is a high probability that the crop
will respond positively to the addition of that nutrient from fertilizer.

A soil-test method must be calibrated with crop response to function as a fertilizer
management tool. However, information from a calibrated soil-test method should not be
used to interpret a soil-test method that is not calibrated. Relating one soil-test method to
another is termed correlation. Correlation of soil-test methods will not be discussed here,
except to say that soil-test results which were obtained from two different extractants
should not be compared directly.

The Calibration Process

Most land grant universities use the calibration process to validate use of a particular
soil-test extractant. In the Southeast, calibration of the Mehlich-I procedure has been
extensive and remains ongoing, especially in Georgia, Alabama, South Carolina, and Florida.

Figures 1 and 2 illustrate the relationship between soil testing and yield response to
added fertilizer, the calibration process. These graphs were plotted using generic data
to illustrate concepts and do not apply to any particular crop or soil-supplied nutrient.
Figure 1 shows typical values for relative yield plotted against preplant soil-test results.
Relative yield is useful in this case because of the way it is calculated:


Relative Yield (%) = Actual yield x 100
Highest actual yield for that year and that location

With this equation, relative yields from many locations and different years can be
plotted on the same graph without worrying about the true magnitudes involved. An
assumption that the range in actual yields is not extremely large must be true; otherwise,
this type of graph will tend to distort the worth of yields at both high and low ends of the
spectrum.

The data displayed in Fig. 1 are obtained by taking both preplant soil samples and yield
measurements at harvest. Of course, such a graph would be composed of data from many
locations, since such a range of soil-test values would not be found at any one location
(research plots excepted). When the relative yield reaches about 97%, the corresponding
soil-test value is usually considered to be the critical value. In this case, the critical
soil-test value would be about 64 ppm.

If the soil-test value were lower than the so-called critical value then fertilizer would
be recommended. More fertilizer is recommended when the soil-test value is considerably
less than the critical value. Less fertilizer is recommended as the soil test approaches the
critical value. Soils with test values above the critical value should be able to supply all of
the particular nutrient in question for proper crop growth. Therefore, that nutrient would
not be specified in the fertilizer recommendation.








In Fig. 2, the relationship between added fertilizer and relative yield is shown. One
curve (open squares) represents what would happen to yield if fertilizer were added to soil
that has a very low soil-test value, e.g., 4 or 8 ppm as shown in Fig. 1. The other curve
(open triangles) illustrates the yield response to added nutrient if the soil-test value were
closer to the critical value, e.g., about 40 ppm from Fig. 1.

Note that, at or above the critical value, only small yield increases can be expected from
fertilizer additions (Fig. 1). Using a relative yield of 97% as the guide, you can see that
adding more fertilizer than about 140 pounds per acre (lb/A) should do little to increase
yield, even when the soil supplies very little of the nutrient (low soil-test curve, Fig 2.).
For this generic situation, 140-lb/A would be the recommended fertilizer rate for this crop
when the soil-test value is very low.

From Fig. 2, 97% relative yield is attained with the addition of about 60 lb/A when
the soil test is in the medium range (open triangles). The soil test indicates that the soil
will contribute some nutrition to the crop, so less fertilizer is needed to optimize yield.

These relationships among relative yield, soil-test value, and added fertilizer do exist
and work well for immobile nutrients. Using these relationships will result in fertilizer use
that is consistent with optimum yield production and yet is ecologically sound.


Relative


Yield vs Soil-Test
Hypothetical Exam'ple


0 20 40 60 80 100
SOIL-TEST VALUE, ppm

Figure 1. Hypothetical relationship between a calibrated soil test and relative yield.


Value










Interpretations of Soil-Test Values


Interpretation is the process which verbally explains the relative meaning of a soil-test
value. The interpretation scale used by the ESTL Laboratory consists of five levels ranging
from Very Low to Very High (Table 2).

By definition, the division between Medium and High is termed the critical value.
Above this point there is no expected crop response to added fertilizer.

Soil-test values lower than the critical value are interpreted as Very Low, Low, or
Medium, indicating the extent to which the soil is deficient with respect to the measured
nutrient. The probability of fertilizer-induced crop response decreases as the soil-test value
approaches the critical value. Thus, less fertilizer is recommended.

When a soil tests Very Low, one can expect less than 50% of the crop-yield potential
without addition of the deficient nutrient. If other nutrient levels and climatic conditions
are suitable, then a positive crop response to added fertilizer is highly probable.

The expected crop yield is only 50 to 75% of the potential when the soil-test value is
rated as Low. Within the Low rating, a positive crop response to added fertilizer is
expected. When the soil test is in the Medium range, between 75 to 100% of the crop
potential is expected and response to fertilizer is Drobable.

Relative Yield vs Fertilizer Added
Hypothetical Example


0 20 40 60 80 100 120 140 160 180 200


0 Louw Soil Test


FERTILIZER ADDED, Ib/A
a. Medi n Soil Test


Figure 2. Hypothetical relationship between fertilizer additions and relative yield.










When the soil-test value is interpreted as High or Very High, it is unlikely that the
crop will respond to added fertilizer. Adding fertilizer to soils testing High or Very High
may provoke nutrient imbalances in the crop, contribute to excessive salt buildup within
the soil profile, and contribute to environmental pollution through leaching of fertilizer from
the soil profile. Adding fertilizer for "insurance" is not recommended since it is both costly
and wasteful of a valuable resource.

Recommendations Based upon Soil Testing

There are two important aspects of effective fertilizer recommendations: fertilizer
amount and relevant fertilizer management practices. Good recommendations cannot
be based upon experience alone, since none of us can afford to experience many different
fertilizer trials or management options. Results from replicated fertilizer trials and
evaluations of management techniques are used by the ESTL to generate fertilizer
recommendations and management-technique footnotes which are both timely and relevant.
These IFAS-based recommendations provide a foundation for sound fertilizer practices that
will ensure adequate fertility for optimum yield without the worry of crop damage or
pollution from excessive fertilizer application.








--- SECTION 2 --


Description of Tests Offered

The following discussion is intended to assist readers with questions regarding the ESTL
services offered to clients. Only tests which have been shown through research/experience
to assist in crop-management decisions are offered by the ESTL to Florida residents. It is
the intention of the Extension Service to offer only analytical procedures whose results can
be interpreted and, thus, render assistance with management decisions involving plants,
soils, and fertilizers.

Certain samples will be analyzed by the ESTL free of charge. Diagnostic samples
submitted by county Extension agents or state-wide Extension faculty of IFAS are among
this group. Also, research samples from IFAS faculty who wish to obtain a standard
fertilizer recommendation will be analyzed at no charge. Contact the ESTL for assistance
with these types of samples.

Commercial Production of Agronomic Crops, Forages, and Vegetables

The extraction solution involving soil-fertility measurements used by the ESTL is the
Mehlich-I extracting solution (0.05 M HC1 + 0.0125 M H2SO4). This extracting solution has
been called the double-acid extractant. However, the preferred Mehlich-I terminology will
be used in this publication. This extractant is intended for sandy soils which have exchange
capacities of less than 10 me/100 g and whose soil pH is less than 6.5. The method is not
suited for alkaline soils (SRIEG 18, 1983).
The Standard Soil Fertility Test for noncalcareous mineral soils and organic soils, the
so-called routine test, provides information concerning soil pH, lime requirement, P, K,
calcium (Ca), and magnesium (Mg). The report specifies the amounts of lime needed, if
any, to adjust the soil pH to a target soil pH range for a specified crop. Needed quantities,
if any, of P20, K20, and Mg to increase the soil's supply of these nutrients for optimum
crop production are specified in pounds per acre. Both P and K recommendations are
expressed as pounds of the oxide per acre (i.e., lb P20O/ac or lb K20/ac), the same system
which is used in expressing the P and K concentration of fertilizers. To comply with current
fertilizer-tag requirements, other recommended nutrients, such as Mg, are reported as
pounds of the element per acre.

An integral part of the recommendations is a section of footnotes which elaborates on
many aspects of fertilization for user-specified crops. Producers should use the information
contained in these footnotes as management guidelines for efficient fertilizer use.

The ESTL also offers a micronutrient test for zinc (Zn), manganese (Mn), and copper
(Cu). Growers should use micronutrient fertilizers with discretion, since it is often possible
to create toxic levels of micronutrients in a soil. Frequently, producers will be adding one
or more of these nutrients with their pesticides, thus, eliminating the need for addition
from fertilizer sources. The primary value of the micronutrient soil test is to show that
adequate levels of these nutrients already exist and, thus, to combat an insurance approach
(commonly called the "shotgun" approach) to fertilization with micronutrients.

The micronutrient soil-test report lists the quantities of Mehlich-I extractable Zn, Mn,
and Cu. A factsheet discussing the interpretation of these results, and proper micronutrient
fertilization, is included with the report.








--- SECTION 2 --


Description of Tests Offered

The following discussion is intended to assist readers with questions regarding the ESTL
services offered to clients. Only tests which have been shown through research/experience
to assist in crop-management decisions are offered by the ESTL to Florida residents. It is
the intention of the Extension Service to offer only analytical procedures whose results can
be interpreted and, thus, render assistance with management decisions involving plants,
soils, and fertilizers.

Certain samples will be analyzed by the ESTL free of charge. Diagnostic samples
submitted by county Extension agents or state-wide Extension faculty of IFAS are among
this group. Also, research samples from IFAS faculty who wish to obtain a standard
fertilizer recommendation will be analyzed at no charge. Contact the ESTL for assistance
with these types of samples.

Commercial Production of Agronomic Crops, Forages, and Vegetables

The extraction solution involving soil-fertility measurements used by the ESTL is the
Mehlich-I extracting solution (0.05 M HC1 + 0.0125 M H2SO4). This extracting solution has
been called the double-acid extractant. However, the preferred Mehlich-I terminology will
be used in this publication. This extractant is intended for sandy soils which have exchange
capacities of less than 10 me/100 g and whose soil pH is less than 6.5. The method is not
suited for alkaline soils (SRIEG 18, 1983).
The Standard Soil Fertility Test for noncalcareous mineral soils and organic soils, the
so-called routine test, provides information concerning soil pH, lime requirement, P, K,
calcium (Ca), and magnesium (Mg). The report specifies the amounts of lime needed, if
any, to adjust the soil pH to a target soil pH range for a specified crop. Needed quantities,
if any, of P20, K20, and Mg to increase the soil's supply of these nutrients for optimum
crop production are specified in pounds per acre. Both P and K recommendations are
expressed as pounds of the oxide per acre (i.e., lb P20O/ac or lb K20/ac), the same system
which is used in expressing the P and K concentration of fertilizers. To comply with current
fertilizer-tag requirements, other recommended nutrients, such as Mg, are reported as
pounds of the element per acre.

An integral part of the recommendations is a section of footnotes which elaborates on
many aspects of fertilization for user-specified crops. Producers should use the information
contained in these footnotes as management guidelines for efficient fertilizer use.

The ESTL also offers a micronutrient test for zinc (Zn), manganese (Mn), and copper
(Cu). Growers should use micronutrient fertilizers with discretion, since it is often possible
to create toxic levels of micronutrients in a soil. Frequently, producers will be adding one
or more of these nutrients with their pesticides, thus, eliminating the need for addition
from fertilizer sources. The primary value of the micronutrient soil test is to show that
adequate levels of these nutrients already exist and, thus, to combat an insurance approach
(commonly called the "shotgun" approach) to fertilization with micronutrients.

The micronutrient soil-test report lists the quantities of Mehlich-I extractable Zn, Mn,
and Cu. A factsheet discussing the interpretation of these results, and proper micronutrient
fertilization, is included with the report.








Landscape and Vegetable Garden Test


Homeowners and gardeners who do not care to use single-nutrient fertilizers are advised
to choose OPTION 1 of the Landscape and Vegetable Garden Test. OPTION 1 includes
soil pH determination and, if the soil is sufficiently acidic, a measure of the lime
requirement (Adams-Evans Buffer Index). The report includes a recommendation for lime
based upon results of the lime requirement and the crops specified by the client. Fertilizer
recommendations accompanying OPTION-1 results are general recommendations and do not
account for nutrients supplied to the plant from sources within the soil. Instead, all
nutrition is assumed to come from fertilizer alone.

OPTION 2 includes information on the major soil-supplied nutrients in addition to soil
pH and lime requirement. Homeowners can modify their fertilization program according
to specific fertilizer recommendations based upon this soil test. Soil pH, Adams-Evans
Buffer Index, P, K, Ca, and Mg are determined. All recommendations are reported as
pounds of nutrient per 1000 square feet, instead of pounds per acre which is used for
commercial crop production.

Forest and Forest Nursery Soil Tests

Recent revisions concerning forest-fertilization programs have changed the role of soil
testing as a fertilizer-management tool. These revisions are the result of research conducted
through the Cooperative Research in Forest Fertilization (CRIFF) program, a regional
project involving both the forest industry and the University of Florida.

The new recommendation system primarily relates to pine plantations (Kidder et al.,
1987) and is based upon the classification of soils into specific soil groups, known as the
CRIFF soil groups (Hanlon and Munson, 1988). Soil testing of pine plantations is
recommended only for CRIFF soil groups A, B, and C, depending upon the age of the stand.
Information on the Pine Plantation and Pine Nursery Soil-Test Information Sheet describes
proper soil-sampling techniques as well as recommendations for other CRIFF soil groups.
This form is available from the nearest county Extension office.

Soil samples for pine plantations will be analyzed for soil pH and Mehlich-I extractable
P. Each soil sample should consist of three separate samples representing the 0- to 8-inch,
the 8- to 16-inch, and the 16- to 24-inch soil depths of the same site.

Pine nursery soil samples should be taken from the 0- to 6-inch soil depth only, and
will be analyzed for soil pH, organic matter, and Mehlich-I extractable P, K, Ca, and Mg.

Container Media Test

This test measures the levels of water-soluble nutrients in soilless media (e.g., mixtures
of materials such as perlite, Styrofoam, peat, pine bark, wood shavings, and sand). The
Container Media Test is recommended as a diagnostic tool for fertilizer management in
commercial container-plant production as a means of monitoring nutrients in the media
throughout the growing season (Ingram and Henley, 1983). Test interpretations are
meaningful only in commercial nursery situations. Unlike other soil tests offered by the
ESTL, container-media samples should NOT be air-dried. Drying the media can affect
adversely the results of the test by changing the amounts of nutrients extracted from the
media.








Landscape and Vegetable Garden Test


Homeowners and gardeners who do not care to use single-nutrient fertilizers are advised
to choose OPTION 1 of the Landscape and Vegetable Garden Test. OPTION 1 includes
soil pH determination and, if the soil is sufficiently acidic, a measure of the lime
requirement (Adams-Evans Buffer Index). The report includes a recommendation for lime
based upon results of the lime requirement and the crops specified by the client. Fertilizer
recommendations accompanying OPTION-1 results are general recommendations and do not
account for nutrients supplied to the plant from sources within the soil. Instead, all
nutrition is assumed to come from fertilizer alone.

OPTION 2 includes information on the major soil-supplied nutrients in addition to soil
pH and lime requirement. Homeowners can modify their fertilization program according
to specific fertilizer recommendations based upon this soil test. Soil pH, Adams-Evans
Buffer Index, P, K, Ca, and Mg are determined. All recommendations are reported as
pounds of nutrient per 1000 square feet, instead of pounds per acre which is used for
commercial crop production.

Forest and Forest Nursery Soil Tests

Recent revisions concerning forest-fertilization programs have changed the role of soil
testing as a fertilizer-management tool. These revisions are the result of research conducted
through the Cooperative Research in Forest Fertilization (CRIFF) program, a regional
project involving both the forest industry and the University of Florida.

The new recommendation system primarily relates to pine plantations (Kidder et al.,
1987) and is based upon the classification of soils into specific soil groups, known as the
CRIFF soil groups (Hanlon and Munson, 1988). Soil testing of pine plantations is
recommended only for CRIFF soil groups A, B, and C, depending upon the age of the stand.
Information on the Pine Plantation and Pine Nursery Soil-Test Information Sheet describes
proper soil-sampling techniques as well as recommendations for other CRIFF soil groups.
This form is available from the nearest county Extension office.

Soil samples for pine plantations will be analyzed for soil pH and Mehlich-I extractable
P. Each soil sample should consist of three separate samples representing the 0- to 8-inch,
the 8- to 16-inch, and the 16- to 24-inch soil depths of the same site.

Pine nursery soil samples should be taken from the 0- to 6-inch soil depth only, and
will be analyzed for soil pH, organic matter, and Mehlich-I extractable P, K, Ca, and Mg.

Container Media Test

This test measures the levels of water-soluble nutrients in soilless media (e.g., mixtures
of materials such as perlite, Styrofoam, peat, pine bark, wood shavings, and sand). The
Container Media Test is recommended as a diagnostic tool for fertilizer management in
commercial container-plant production as a means of monitoring nutrients in the media
throughout the growing season (Ingram and Henley, 1983). Test interpretations are
meaningful only in commercial nursery situations. Unlike other soil tests offered by the
ESTL, container-media samples should NOT be air-dried. Drying the media can affect
adversely the results of the test by changing the amounts of nutrients extracted from the
media.








Landscape and Vegetable Garden Test


Homeowners and gardeners who do not care to use single-nutrient fertilizers are advised
to choose OPTION 1 of the Landscape and Vegetable Garden Test. OPTION 1 includes
soil pH determination and, if the soil is sufficiently acidic, a measure of the lime
requirement (Adams-Evans Buffer Index). The report includes a recommendation for lime
based upon results of the lime requirement and the crops specified by the client. Fertilizer
recommendations accompanying OPTION-1 results are general recommendations and do not
account for nutrients supplied to the plant from sources within the soil. Instead, all
nutrition is assumed to come from fertilizer alone.

OPTION 2 includes information on the major soil-supplied nutrients in addition to soil
pH and lime requirement. Homeowners can modify their fertilization program according
to specific fertilizer recommendations based upon this soil test. Soil pH, Adams-Evans
Buffer Index, P, K, Ca, and Mg are determined. All recommendations are reported as
pounds of nutrient per 1000 square feet, instead of pounds per acre which is used for
commercial crop production.

Forest and Forest Nursery Soil Tests

Recent revisions concerning forest-fertilization programs have changed the role of soil
testing as a fertilizer-management tool. These revisions are the result of research conducted
through the Cooperative Research in Forest Fertilization (CRIFF) program, a regional
project involving both the forest industry and the University of Florida.

The new recommendation system primarily relates to pine plantations (Kidder et al.,
1987) and is based upon the classification of soils into specific soil groups, known as the
CRIFF soil groups (Hanlon and Munson, 1988). Soil testing of pine plantations is
recommended only for CRIFF soil groups A, B, and C, depending upon the age of the stand.
Information on the Pine Plantation and Pine Nursery Soil-Test Information Sheet describes
proper soil-sampling techniques as well as recommendations for other CRIFF soil groups.
This form is available from the nearest county Extension office.

Soil samples for pine plantations will be analyzed for soil pH and Mehlich-I extractable
P. Each soil sample should consist of three separate samples representing the 0- to 8-inch,
the 8- to 16-inch, and the 16- to 24-inch soil depths of the same site.

Pine nursery soil samples should be taken from the 0- to 6-inch soil depth only, and
will be analyzed for soil pH, organic matter, and Mehlich-I extractable P, K, Ca, and Mg.

Container Media Test

This test measures the levels of water-soluble nutrients in soilless media (e.g., mixtures
of materials such as perlite, Styrofoam, peat, pine bark, wood shavings, and sand). The
Container Media Test is recommended as a diagnostic tool for fertilizer management in
commercial container-plant production as a means of monitoring nutrients in the media
throughout the growing season (Ingram and Henley, 1983). Test interpretations are
meaningful only in commercial nursery situations. Unlike other soil tests offered by the
ESTL, container-media samples should NOT be air-dried. Drying the media can affect
adversely the results of the test by changing the amounts of nutrients extracted from the
media.








Included in the Container Media Test are analyses for pH, electrical conductivity,
nitrate-N, P, K, Ca, and Mg, all of which are measured in an extract from a water-satur-
ated paste of the soilless media (Ingram and Henley, 1983). This report provides updated
tables assisting with interpretation of results of the Container Media Test, as well as
general fertilization guidelines. By using the Container Media Test regularly throughout
the growing season, commercial producers can tailor interpretations and fertilizer
recommendations to their individual management situations.

Water Test

The water test conducted by the ESTL is applicable for both home and irrigation
waters. The ESTL provides a home-water testing service for mineral determinations only;
all health-related inquiries should be directed to the nearest county health department.
Municipal water sources are monitored for public safety by the Department of Health and
Rehabilitative Services. Questions concerning municipal water quality should be referred
to that agency.

Values reported in the water test include pH, sodium (Na), Ca, Mg, iron (Fe), chloride
(Cl), total carbonates and bicarbonates, and electrical conductivity. Interpretations for
home-water quality and irrigation-water quality are included with the report.

In Florida, many irrigation-water sources originate from limestone aquifers, resulting
in high-pH waters. pH-sensitive crops, such as blueberries or pine seedlings, may benefit
considerably by pretreating such water with acid to destroy carbonates and concurrently
lower the water pH. Results from the total carbonates and bicarbonates test can be used
to determine the amount of acid required to reduce this high-pH condition. Treatment of
water with acid for agricultural purposes is discussed by Kidder and Hanlon (1985). A
testing kit is available to Extension faculty for field testing of carbonates (Hanlon and
DeVore, 1986).

How to Submit Samples to the ESTL

Soil Samples

Soil sampling literature, including request forms for all of the tests discussed above,
sample bags, and mailing boxes are available from the nearest county Extension Office.
Notes in Soil Science No. 2D briefly describes the ESTL testing services and indicates under
which conditions each test may be applicable.

Water Samples

The container in which a water sample is sent to the ESTL can influence results
greatly. The container should be either made of plastic or glass and clean to avoid
contamination of the sample. Thoroughly flush the container several times with the flowing
water. The sample should be taken several minutes after the water source has been
flowing from the spigot or irrigation pump. The container should be filled completely with
no airspace at the container top.








Methods of Sample Delivery to the ESTL


Samples may be mailed or shipped to the ESTL or delivered directly to the ESTL to
save mailing delays. After testing is completed (normally three working days after sample
receipt at the ESTL), results are mailed directly to the return address entered by the client
on the request sheet. A copy of these results is sent to the county Extension office.
Occasionally, return mail may be too slow to permit timely management decisions.
Most county Extension offices have the capacity to receive testing results via electronic mail.
Currently, there is no extra charge for this service. County agents may contact the ESTL
by telephone in extreme cases.








--- SECTION 3 ---


Lime Requirement and Fertilizer Recommendations

Lime Requirement

The Adams-Evans Buffer test (Adams and Evans, 1962) is used to determine the lime
requirement, if any, for soil samples which have a soil pH below 6.0. This buffer system
is more accurate when prescribing appropriate liming rates than when making a liming
recommendation based on soil pH alone. Soil pH does not predict the buffering capacity
of the soil, often called the reserve acidity. Many complex chemical factors contribute to
reserve acidity and some form of buffering system is required to measure accurately this
form of acidity. While other techniques may be used, most of the alternate methods are not
suited for rapid laboratory analysis.

The original Adams and Evans procedure to calculate lime requirement has been
replaced by a more accurate procedure calibrated with soils from Florida. This new
approach uses the soil pH (2:1 V:V), a target soil pH, and the resultant pH of the soil
mixed with the Adams-Evans Buffer, the so-called Buffer Index pH (Dierolf and Kidder,
1986).

In this context, soil pH should be adjusted to the target soil pH. A target pH based
upon crop performance, nutrient availability, and experience, is specified for various crops
in Tables 4, 6, 8, and 10. The following equation is used to determine lime requirement:

Lime Requirement =

26.1 3.40 x (Buffer Index pH) + 1.02 x (target soil pH soil pH)

where:
Buffer Index pH is obtained by reacting the Adams-Evans buffer
with a soil sample and then measuring the resultant pH;

Target soil pH is the pH to which the soil should be adjusted;

Soil pH is the pH of a 2:1 soil-water suspension.

This equation is used in the ESTL recommendation computer program, when needed.
The lime requirement is rounded to the nearest 0.5 ton of lime for all Extension soil
samples. Two examples are given to make the use of the equation clear.


Example 1. Assume that the crop is mulched tomatoes and therefore that the target soil
pH is 6.5 (Table 6). The soil pH was measured as 5.5 with a Buffer Index pH of 7.45.
Substituting these values into the above equation yields:

26.1 3.40 x (7.45) + 1.02 x (6.5 5.5) = 1.8 tons of ag lime per acre (T/A).

Rounding to the nearest 0.5 T/A, the recommendation would be for 2.0 T lime/A. If
2.0 T/A of ag lime (either dolomite or calcitic lime) were added to this soil, then the soil
pH should approach 6.5 as the lime reacts with the soil's reserve acidity. The speed of this








--- SECTION 3 ---


Lime Requirement and Fertilizer Recommendations

Lime Requirement

The Adams-Evans Buffer test (Adams and Evans, 1962) is used to determine the lime
requirement, if any, for soil samples which have a soil pH below 6.0. This buffer system
is more accurate when prescribing appropriate liming rates than when making a liming
recommendation based on soil pH alone. Soil pH does not predict the buffering capacity
of the soil, often called the reserve acidity. Many complex chemical factors contribute to
reserve acidity and some form of buffering system is required to measure accurately this
form of acidity. While other techniques may be used, most of the alternate methods are not
suited for rapid laboratory analysis.

The original Adams and Evans procedure to calculate lime requirement has been
replaced by a more accurate procedure calibrated with soils from Florida. This new
approach uses the soil pH (2:1 V:V), a target soil pH, and the resultant pH of the soil
mixed with the Adams-Evans Buffer, the so-called Buffer Index pH (Dierolf and Kidder,
1986).

In this context, soil pH should be adjusted to the target soil pH. A target pH based
upon crop performance, nutrient availability, and experience, is specified for various crops
in Tables 4, 6, 8, and 10. The following equation is used to determine lime requirement:

Lime Requirement =

26.1 3.40 x (Buffer Index pH) + 1.02 x (target soil pH soil pH)

where:
Buffer Index pH is obtained by reacting the Adams-Evans buffer
with a soil sample and then measuring the resultant pH;

Target soil pH is the pH to which the soil should be adjusted;

Soil pH is the pH of a 2:1 soil-water suspension.

This equation is used in the ESTL recommendation computer program, when needed.
The lime requirement is rounded to the nearest 0.5 ton of lime for all Extension soil
samples. Two examples are given to make the use of the equation clear.


Example 1. Assume that the crop is mulched tomatoes and therefore that the target soil
pH is 6.5 (Table 6). The soil pH was measured as 5.5 with a Buffer Index pH of 7.45.
Substituting these values into the above equation yields:

26.1 3.40 x (7.45) + 1.02 x (6.5 5.5) = 1.8 tons of ag lime per acre (T/A).

Rounding to the nearest 0.5 T/A, the recommendation would be for 2.0 T lime/A. If
2.0 T/A of ag lime (either dolomite or calcitic lime) were added to this soil, then the soil
pH should approach 6.5 as the lime reacts with the soil's reserve acidity. The speed of this








reaction is dependent upon the fineness of the lime particles, soil moisture, temperature,
and depth and method of lime incorporation into the soil. A rule of thumb often quoted
is that this reaction will be complete about 6 months after application. However, under
good conditions, much of the pH change will have taken place in the first few weeks after
lime application.


Example 2. Assume that the crop is wheat for grain with a target pH of 6.0 (Table 4).
The soil pH is 5.8 and the Buffer Index pH was measured at 7.55. Substituting into the
preceding equation:

26.1 3.40 x (7.55) + 1.02 x (6.0 5.8) = 0.6 tons of aglime per acre (T/A).

After rounding, the recommendation would be for 0.5 T lime/A. In this case, the
grower may wish to wait another season and retest the soil's lime requirement. Since the
soil's pH is so close to the target pH in this case, it is unlikely that wheat yield would
benefit from the addition of lime.

The primary reasons why lime is added to soil are to reduce any toxic effects of soil
aluminum and to improve nutrient availability for plants. Like fertilizers, lime should be
added when it will cause a positive crop response. Florida's sandy soils contain low
amounts of plant-available aluminum and have relatively low amounts of reserve acidity.
Both conditions result in the fact that small amounts of lime are needed. In fact,
overliming is now a common problem in Florida.

Irrigation waters from many of Florida's aquifers contain enough dissolved lime to add
more than 0.5 T/A per growing season. This source of lime should be considered for
irrigated crops to avoid the nutrient-availability problems that can result when soil pH is
too high for proper crop growth. Besides quantifying the amount of lime that may be
needed to modify soil pH, the ESTL furnishes additional information through a series of
footnotes. Those footnotes which address questions related to soil pH and liming are found
in Table 1. These footnotes are chosen programmatically for each sample based upon the
sample's crop code, soil pH, Buffer Index pH, Target Soil pH, and Mehlich-I extractable Ca
and Mg levels.








Table 1. Text of all soil pH and liming footnotes. Only relevant footnotes are used for each soil sample.
Appropriate footnotes are cited as dictated by each sample's particular soil-test results and selected crop.
No. Footnote
801 Either calcitic or dolomitic limestone may be used.
802 Recommendations are based on the Adams-Evans lime requirement test which is run on all
mineral soils having a pH below 6.0. When the recommended amount of lime is incorporated
in the surface 6 inches of soil, soil pH should adjust to a level above which additional liming
benefit is not expected. Excessive applications of lime can result in nutritional disorders.
803 Lime soil with either dolomite or dolomitic limestone.
804 Magnesium (Mg) fertilizer is recommended. Dolomite is an economical, long-lasting source of
Mg. Since this soil has a pH below 6.4, up to 1/2 ton dolomite/A may be used to supply Mg
with little danger of over-liming. Alternatively, use 35 Ib Mg/A of a more-soluble Mg source, such
as magnesium sulfate or potassium magnesium sulfate, blended with other fertilizers.

805 Apply 500 Ib gypsum/A as a calcium fertilizer source.
806 Apply the equivalent of 35 Ib Mg/A in a soluble form, such as magnesium sulfate or potassium
magnesium sulfate.
807 Lime requirement is not currently determined on soils containing more than about 15% organic
matter.
808 It is generally impractical to apply less than one ton of agricultural lime per acre. Since the lime
need is small, you may elect to either apply no lime or to apply 1 ton lime/A this year. A soil test
taken in alternate years will help monitor soil pH and insure proper lime management.
810 The Adams-Evans lime requirement test is not valid and thus not run on soils that exhibit a pH
greater than 6.0.
814 Magnesium (Mg) fertilizer is recommended. Dolomite is an economical, long-lasting source of
Mg. Since this soil has a pH below 6.4, up to 20 Ib dolomite per 1000 sq. ft. may be used to
supply Mg with little danger of over-liming. Alternatively, use 0.2 Ib Mg per 1000 sq. ft. of a
more-soluble Mg source, such as magnesium sulfate or potassium magnesium sulfate, blended
with other fertilizers.
815 Apply 10 Ib gypsum per 1000 sq. ft as a calcium fertilizer source.

818 Since the lime need is small, you may elect to either apply no lime or to apply 45 Ib lime per 1000
sq. ft. this year. A soil test taken in alternate years will help monitor soil pH and ensure proper
lime management.
819 The pH of this soil is quite high. If this is a natural condition (i.e., if it is not from the over-
application of lime), it is generally impractical to lower the soil pH with soil amendments. Use
plant species that are tolerant of high soil pH.








IFAS Standardized Fertilizer Recommendations


After a soil sample has been extracted with the Mehlich-I extractant and the extract
analyzed, a computer program using the information presented in Tables 2 and 3 assigns
an interpretation value of Very Low (VL), Low (LO), Medium (MED), High (HI), or
Very High (VH) to the P, K, and Mg soil-test values. The computer program uses these
interpretations to determine the IFAS Standardized Fertilizer Recommendation for each of
these nutrients. The specific fertilizer levels of P205 and K20, given in lb/A, are listed by
crop and soil-test interpretation in Tables 4, 6, 8, 10, and 12. These tables also contain the
target soil pH and the recommended N fertilizer level for each crop.

Tables 5, 7, 9, 11, and 13 contain the important second half of any good recommenda-
tion footnotes detailing management practices for optimum fertilizer-use efficiency. In
addition to footnotes listed by crop, added information may be obtained by consulting the
publications listed as references, which also serve as the source documents for the IFAS
Standardized Fertilizer Recommendations. A complete listing of each footnote is given in
Tables 14a through 14g.

Examples of the manual use of these tables may be of benefit to those who wish to use
the soil-test results for additional crops not originally specified when the soil sample was
sent to the ESTL. Do not use these tables for soil-test results which were obtained by
other extractants. Such use will lead to incorrect interpretations and fertilizer recommenda-
tions.

Example 1. Soil-test results for a soybean field show the following values:

Adams-Evans Mehlich I extractable
Soil Buffer Index P K Mg Ca
pH pH --------------- ppm ---------------

6.5 --- 12 120 45 >2000

Using Table 2, the soil-test values are interpreted as follows:

Adams-Evans Mehlich I extractable
Soil Buffer Index P K Mg Ca
pH pH ------------- ppm ---------------

LO HI HI ---

Notice that no interpretation of Ca is given. Mehlich-I extractable Ca is used only for
the determination of the type of limestone to be recommended, where liming is needed.
For most soils and most crops, liming to insure an adequate soil pH for proper crop growth
will insure a more-than-adequate concentration of Ca for proper crop growth. Research
results (Adams and Hartzog, 1980) have shown no crop response to added Ca, from either
liming materials or gypsum, when the Mehlich-I extractable Ca level is above 250 ppm.
The production of peanuts for seed is an exception to this statement and is addressed by
an appropriate footnote.

Consulting Table 4 of this section for soybeans (crop code 11), the target pH (6.5) and
the soil-test pH (6.5) are the same hence no lime is required at this time. Zero Ib N/A
are needed, since soybeans are nitrogen-fixing legumes. Looking under the P20, "LO"









column, the IFAS Standardized Fertilizer Recommendation would be for 40 lb P20O/A.
Moving under the KIO section to the column labeled "HI", the IFAS Standardized Fertilizer
Recommendation would be for zero lb K0O/A. Referring to Table 3, zero lb Mg/A would
be recommended. A summary of these recommendations is listed below:

Lime Requirement P205 K20 Mg
Tons Lime/A -------- lb/A --------

0 40 0 0

From Table 5 of this section for soybeans, footnotes 108, 124, and 128 would be printed
to clarify and to amplify the correct cultural practices to be followed concerning this
recommendation. The text of these footnotes can be found in Table 14a.

Example 2. Soil-test results for muskmelons growing under full-bed plastic mulch indicate
the following values:

Adams-Evans Mehlich I extractable
Soil Buffer Index P K Mg Ca
pH pH -------- ppm -------------

5.9 7.55 9 40 48 >2000

Using Table 2, the soil-test values in this case for vegetable crops are interpreted as
follows:

Adams-Evans Mehlich I extractable
Soil Buffer Index P K Mg Ca
pH pH -------ppm --------------

VL MED HI ---

Consulting Table 6 for mulched muskmelon (crop code 206), the target pH (6.5) is
greater than the soil-test pH (5.9). Using the equation given in section A above, the
calculated lime requirement is only 0.38 ton lime/A. Rounding to the nearest 0.5 ton
lime/A, the lime recommendation would be for 0.5 ton lime/A. In addition, 120 Ib N/A
are needed. Looking under the column labeled "VL" in the P205 section of Table 6, the
IFAS Standardized Fertilizer Recommendation would be for 160 Ib P2zO/A. Moving under
the K20 section to the column labeled "MED", the IFAS Standardized Fertilizer Recom-
mendation would be for 100 lb K20/A. Referring to Table 3, zero lb Mg/A would be
recommended. A summary of these recommendations is listed below:

Lime Requirement N P205 KO2 Mg
Tons Lime/A ------------ LB/A ---------------

0.5 120 160 100 0

From Table 7 for mulched muskmelons, footnotes 250, 350, 351, 352, and 354 would
be printed to clarify the cultural practices to be followed in association with this
recommendation. The text of these footnotes can be found in Table 14b.









Table 2. Current Mehlich-1, soil-test interpretations used in the IFAS-wide Standardized Fertilizer
Recommendation System.


Mineral, organic, and organic-mineral intergrade soils


Rating
Element Crop Very Very
Low Low Medium High High
(VL) (LO) (MED) (HI) (VHI)

parts per million (ppm)


P All <10 10-15 16-30 31-60 >60

K All <20 20-35 36-60 61-125 > 125


<15


15-30


>30


Table 3. IFAS standardized fertilizer recommendations for magnesium, all crops.

Rating
Element
Low Medium High
LO MED HI

Ib Mg/A

Mg 35 20 0


If lime is needed (based upon the crop, soil pH, and Buffer Index pH) and the Mg soil test result is interpreted
as LO, or MED, the ESTL computer program will recommend application of dolomitic limestone. Otherwise, the
program will generally recommend Mg from other fertilizer sources.







Table 4. Target pH, and recommended N, P20,, and K,0 fertilizer rates for agronomic crops. Phosphorus and K rates are based on interpretation of a Mehlich-I
soil test.


CROP CROP
CODE DESCRIPTION


TARGET

pH N


Ib/A/year

P,20, K,0 -


1 NON-IRRIG CORN, 10M/A*
2 NON-IRRIG CORN, 12.5M/A
3 NON-IRRIG CORN 15M/A
4 IRRIGCORN, 20M/A
5 IRRIGCORN, 25M/A
6 IRRIGCORN, 30M/A
7 GRAIN SORGHUM OR
FORAGE SORGHUM FOR
SILAGE
8 TRITICALE, OATS, OR RYE
FOR GRAIN
M 9 COTTON
10 PEANUTS
11 SOYBEANS
12 FLUE-CURED TOBACCO
13 SUGAR CANE FOR SYRUP
14 SUMMER ANNUAL GRASSES
21 WARM SEASON LEGUMES
22 COOL SEASON LEGUMES OR
LEGUME-GRASS MIXTURES
23 ALFALFA
24 BAHIAGRASS PASTURE
High-N Option
Medium-N Option
Low-N Option
25 IMPROVED PERENNIAL
GRASSES (EXCLUDING BAHIA)
26 COOL SEASON ANNUAL
GRASSES
27 WHEAT FOR GRAIN
28 WARM SEASON
LEGUME-GRASS MIXTURES


Ib/A VL LO

120 100 80
150 125 100
180 150 120
180 150 120
210 175 140
240 200 160
150 125 100


6.0 70 100 80


60 120 90
0 100 80
0 60 40
80 100 80
90 100 80
** 80 80
0 30 30
0 125 100


7.0 0 150 125


160 40 40
100 25 25
50 0 0
160 40 40


6.0 80 100 80


80 100 80
0 80 80


MED HI VH VL LO MED


0 100 80
0 120 100
0 150 120
0 150 120
0 175 140
0 200 160
0 125 100


40 0 0 100 80


40 0 0


0 125 100 70
0 100 80 40
0 60 40 20
0 200 160 120
0 100 80 40
0 80 80 40
0 60 60 30
0 200 160 120


80 0 0 200 160 120


0 0


80 80
50 80
0 0
80 40


40 0 0 100 80


40 0 0


0 100 80
0 80 80


* 10M/A refers to 10,000 plants per acre.
** Nitrogen recommendation is contained in footnotes 111 and 112.








Table 5. Applicable footnote numbers and additional reading for agronomic crops.


CROP CROP
CODE DESCRIPTION

1 NON-IRRIG CORN, 10M/A
2 NON-IRRIG CORN, 12.5 M/A
3 NON-IRRIG CORN, 15 M/A
4 IRRIG CORN, 20 M/A
5 IRRIG CORN, 25 M/A
6 IRRIG CORN, 30 M/A
7 GRAIN SORGHUM OR FORAGE
SORGHUM FOR SILAGE
8 TRITICALE, OATS, OR RYE
FOR GRAIN
9 COTTON
10 PEANUTS
11 SOYBEANS
12 FLUE-CURED TOBACCO
13 SUGARCANE FOR SYRUP
14 SUMMER ANNUAL GRASSES
21 WARM SEASON LEGUMES
22 COOL SEASON LEGUMES OR
LEGUME-GRASS MIXTURES
23 ALFALFA
24 BAHIAGRASS PASTURE
25 IMPROVED PERENNIAL
GRASSES(EXCLUDING BAHIA)
26 COOL SEASON ANNUAL
GRASSES
27 WHEAT FOR GRAIN
28 WARM SEASON
LEGUME-GRASS MIXTURES


FOOTNOTES

101 120 124
102 120 124
103 120 124
103 120 124
104 120 124
105 120 124
106124

106124

107 124
108 109 118 124
108 124 128
110 124
106 124
111 124
121 124
115 122 124 129

116 120 123 124
124 131
124 125 126

112 124

124 127
121 124


REFERENCES

Agronomy Facts 70
Agronomy Facts 70
Agronomy Facts 70
Agronomy Facts 70
Agronomy Facts 70
Agronomy Facts 70
Agronomy Facts 70

Agronomy Facts 133 and 147

Agronomy Facts 111
Agronomy Facts 70
Notes in Soil Science 23
Agronomy Facts 70
Agronomy Facts 70
Agronomy Facts 147
Agronomy Facts 147
Agronomy Facts 147

Agronomy Facts 147
Agronomy Facts 70 and 147
Agronomy Facts 70 and 147

Agronomy Facts 70 and 147

Agronomy Facts 133 and 147
Agronomy Facts 147







Table 6. Target pH, and recommended N, P20,, and K20 fertilizer rates for commercial vegetable production. Phosphorus and K rates are based on
interpretation of a Mehlich-l soil test (IFAS Circular 806).


Crop Crop
Code Description


200 Tomato or pepper
201 Mulched tomato
202 Mulched pepper
203 Eggplant
204 Mulched eggplant
205 Muskmelon
206 Mulched muskmelon
207 Head cabbage
208 Mulched head cabbage
209 Lettuce and endive
210 Cucumber, squashes, or
spinach
211 Mulched cucumber or
Squash
212 Broccoli or cauliflower
213 Mulched broccoli or
cauliflower
214 Celery
215 Irish potato
216 Bushbeans, southern or
English peas
217 Lima or pole beans
218 Sweet potato
219 Radish
220 Sweet corn
221 Watermelon
222 Mulched watermelon
223 Onion
224 Mulched strawberry
225 Mustard or turnip
226 Chinese cabbage or
carrots
227 Okra or collard
228 Beets
90 Vegetable garden


Target
pH N
Ib/A

6.5 160
6.5 160
6.5 160
6.5 120
6.5 120
6.5 120
6.5 120
6.5 120
6.5 120
6.5 110
6.5 90


P,20,
VL LO MED

160 130 100
160 130 100
160 130 100
160 130 100
160 130 100
160 130 100
160 130 100
160 130 100
160 130 100
150 120 90
120 100 80


6.5 90 120 100


6.5 110
6.5 110

6.5 200
6.0 150
6.5 60

6.5 90
6.5 60
6.5 90
6.0 120
6.0 120
6.0 120
6.5 120
6.5 120
6.5 110
6.5 110

6.5 110
6.5 90
6.5 100


150 130 100
150 130 100

300 200 100
120 120 60
80 80 60

120 120 80
120 120 80
120 120 80
120 120 80
160 160 100
160 160 100
120 100 80
160 160 100
150 130 100
150 130 100

150 130 100
120 120 80
140 140 70


lb/A/year

HI VH VL LO


K,O
MED HI VH


0 160 130
130 100
0 160 130
0 160 130
0 160 130
0 160 130
0 160 130
0 160 130
0 160 130
0 150 120
0 120 100


80 0 0 120 100


150 130
150 130

300 200
140 140
80 80

120 120
120 120
120 120
120 120
120 100
120 100
120 100
160 160
150 130
150 130

150 130
120 120
140 140


80 0 0


100 0
100 0


100 0
80 0
70 0











Table 7. Applicable footnotes and additional reading for commercial vegetable production.


CROP
CODE
200
201

202

203
204

205
206

207
208

209
210

211

212

213

214
215


* SCSSFP refers to the Soil and Crop Science Society of Florida Proceedings, and SSSAJ refers to the Soil
Science Society of America Journal.


CROP
DESCRIPTION
TOMATO OR PEPPER
MULCHED TOMATO

MULCHED PEPPER

EGGPLANT
MULCHED EGGPLANT

MUSKMELON
MULCHED MUSKMELON

HEAD CABBAGE
MULCHED HEAD CABBAGE

LETTUCE AND ENDIVE
CUCUMBER, SQUASHES,
OR SPINACH
MULCHED CUCUMBER
OR SQUASH
BROCCOLI
OR CAULIFLOWER
MULCHED BROCCOLI
OR CAULIFLOWER
CELERY
IRISH POTATO


BUSHBEANS, SOUTHERN
OR ENGUSH PEAS
LIMA OR POLE BEANS
SWEET POTATO
RADISH
SWEET CORN
WATERMELON

MULCHED WATERMELON

ONION
MULCHED STRAWBERRY

MUSTARD OR TURNIP
CHINESE CABBAGE OR
CARROTS
OKRA OR COLLARD 250 251
BEETS
VEGETABLE GARDEN


FOOTNOTES
250 251 354
250 350 351 352
353354
250 350 351 352
353 354
250 251 354
250 350 351 352
353354
250 251 354
250 350 351
352 354
250 251 354
250 350 351 352
354
250 251 354
250 251

250 350 351 352
354
250 251 354

250 350 351
352 354
250 251 354
251 253


250 251

250 251
250 251
250 251 252
250 251
250 251 354

250 350 351 352
354
250350354
250 350 352
353 354355
250 251
250 251


250 251
901 through 909


REFERENCES
Circulars 98C & 225C
Circulars 98 & 225C

Circulars 102E, 109,
and 225-C
Circulars 102E & 225C
Circular 225C

Circulars 122C & 225C
Circulars 122C & 225C

Circulars 117E & 225C
Circulars 123 & 225C

Circulars 123 & 225C
Circulars 101D, 103D
& 225C
Circulars 101D, 103D
& 225C
Circulars 555 and 225-C

Circulars 555 and 225-C

Bulletin 757 & Circular 225C
Circulars H8 & 225C,
SSSAJ 47:266 -270, &
SCSSFP 41:193 -195
Circulars 100, 225-C, and
478
Circulars 100 and 225-C
Circulars 440-11, 551 & 225C
Circular 225-C
Circular 99D & 225C
Circulars 96G, 122, and
225-C
Circulars 96G, 122, and
225-C
Circulars 176E, 225-C & Bulletin 238
DOVER ARC SV 1978-2 and
Circulars 142 & 225C
Circular 225-C
Circular 225-C

Circular 225-C
Circular 492
Circular 104P and Veg Crops
Factsheet 74-3








Table 8. Target pH for citrus and blueberry production. Soil testing is not used in determining fertilizer rates
for these commodities.

CROP CROP TARGET
CODE DESCRIPTION pH

60 CITRUS (ESTABLISHMENT) 6.5
61 CITRUS (BEARING TREES) OR 6.5
DOORYARD CITRUS
67 BLUEBERRY (BEARING) 4.0


Table 9. Applicable footnotes and additional reading for citrus and blueberry production.

CROP CROP
CODE DESCRIPTION FOOTNOTES REFERENCES

60 CITRUS (ESTABUSHMENT) 402 403 405 Bulletin 536D
61 CITRUS (BEARING TREES) OR 402 404 405 Bulletin 536D
DOORYARD CITRUS
67 BLUEBERRY (BEARING) 401 408 Fruit Crops Factsheet 46 and
Circular 397






Table 10. Target pH, and recommended N, P205, and K20 fertilizer rates for turfgrass production and lawns. Phosphorus and K rates are based on
interpretation of a Mehlich-l soil test.


CROP CROP
CODE* DESCRIPTION


TARGET
pH


71 ATHLETIC FIELD,GOLF
GREEN,TEE, OR FAIRWAY
72 BAHIAGRASS LAWN
73 BERMUDAGRASS
LAWN, NORTH
73 BERMUDAGRASS
LAWN, SOUTH
74 CARPETGRASS LAWN
75 CENTIPEDEGRASS
LAWN, NORTH
75 CENTIPEDEGRASS
LAWN, SOUTH
76 RYEGRASS LAWN
77 ST. AUGUSTINE LAWN,
NORTH
77 ST. AUGUSTINE LAWN,
SOUTH
78 ZOYSIAGRASS LAWN,
NORTH
78 ZOYSIAGRASS LAWN,
SOUTH


N P2O,
VL LO MED


1.0 1.0 0.5
1.0 1.0 0.5

2.0 2.0 1.0

1.0 1.0 0.5
1.0 1.0 0.5

1.0 1.0 0.5

0.5 0.5 0.2
1.0 1.0 0.5

1.0 1.0 0.5

2.0 2.0 0.5

1.0 1.0 0.5


- b/1000 sq ft/year
K20
HI VH VL LO MED HI VH


2.0 2.0 1.0 0
2.0 2.0 1.0 0

3.0 3.0 1.5 0

1.0 1.0 0.5 0
2.0 2.0 1.0 0

2.0 2.0 1.0 0

1.0 1.0 0.5 0
2.0 2.0 1.0 0

3.0 3.0 1.5 0

2.0 2.0 1.0 0

2.0 2.0 1.0 0


* Samples sent from counties north of Orlando, including the panhandle, are assigned recommendations for the northern section of the state. This
North/South distinction is automatically made by the computer program based upon the specified county.









Table 11. Applicable footnotes and additional reading for turfgrass and lawns.


CROP CROP
CODE* DESCRIPTION


FOOTNOTES


71 ATHLETIC FIELD, GOLF
GREEN, TEE, OR
FAIRWAY
72 BAHIAGRASS LAWN
73 BERMUDAGRASS LAWN,
NORTH
73 BERMUDAGRASS LAWN,
SOUTH
74 CARPETGRASS LAWN
75 CENTIPEDEGRASS LAWN,
NORTH
75 CENTIPEDEGRASS LAWN,
SOUTH
76 RYEGRASS LAWN
77 ST. AUGUSTINE LAWN,
NORTH
77 ST. AUGUSTINE LAWN,
SOUTH
78 ZOYSIAGRASS LAWN, NORTH
78 ZOYSIAGRASS LAWN, SOUTH


REFERENCES


Soil Science fact sheet SL-21


Soil Science fact sheet SL-21
Soil Science fact sheet SL-21

Soil Science fact sheet SL-21

Soil Science fact sheet SL-21
Soil Science fact sheet SL-21

Soil Science fact sheet SL-21


Soil Science fact sheet SL-21

Soil Science fact sheet SL-21


501 Soil Science fact sheet SL-21
501 Soil Science fact sheet SL-21


* Samples sent from counties north of Orlando, including the panhandle, are assigned recommendations for
the northern section of the state. This North/South distinction is automatically made by the computer program
based upon the specified county.






Table 12. Target pH, and recommended N, P20,, and K,0 fertilizer rates for ornamentals in commercial production and ornamentals in the landscape.
Phosphorus and K rates are based on interpretation of a Mehlich-I soil test.

CROP CROP TARGET lb/1000 sq ft/year
CODE DESCRIPTION pH N P205 K20
VL LO MED HI VH VL LO MED HI VH


600 COMMERCIAL WOODY
ORNAMENTAL NURSERY
GROWING PLANTS IN
THE GROUND
601 COMMERCIAL NURSERY
AZALEAS, CAMELLIAS,
GARDENIAS, HIBISCUS, OR
IXORA IN THE GROUND
602 WOODY ORNAMENTALS OR
TREES IN THE
LANDSCAPE
603 AZALEAS, CAMELLIAS,
GARDENIAS, HIBISCUS,
OR IXORA IN THE
LANDSCAPE


6.0 6.9



5.5 3.4



6.0 2.3


5.5 1.1


2.3 2.3 1.1 0 0



1.1 1.1 0.7 0 0



0.7 0.7 0.4 0 0


0.3 0.3 0.2 0 0


4.6 4.6 2.3



2.3 2.3 1.1



1.4 1.4 0.7


0.7 0.7 0.3


0 0



0 0



0 0


0 0










Table 13. Applicable footnote numbers and additional reading for ornamentals in commercial production
and ornamentals in the landscape.


CROP
DESCRIPTION

COMMERCIAL WOODY
ORNAMENTAL NURSERY
GROWING PLANTS IN
THE GROUND
COMMERCIAL NURSERY
GROWING AZALEAS,
CAMELLIAS, GARDENIAS,
HIBISCUS, AND IXORA
IN THE GROUND
WOODY ORNAMENTALS AND
TREES IN THE
LANDSCAPE
AZALEAS, CAMELLIAS,
GARDENIAS, HIBISCUS,
AND IXORA IN THE
LANDSCAPE


FOOTNOTES

650, 651,652



650, 651, 652




650, 653, 654


650, 653, 654


REFERENCES

Bulletin 793



Circulars 460 and
461



Ornamental
Horticulture fact
sheets 37 and 44
Ornamental
Horticulture fact
sheets 37 and 44


CROP
CODE










Table 14a. Footnotes used with agronomic crops.
101 Apply all of the P,05, 30% of the K,0, and 20 Ib N/A in a preplant or at-planting application. Four
weeks after planting, sidedress the remaining 70% of the K,0. Apply the remaining 100 Ib N/A
in two or more sidedressings, one of which should be at 4 weeks.
102 Apply all of the P205, 30% of the K20, and 30 Ib N/A in a preplant or at-planting application. Four
weeks after planting sidedress the remaining 70% of the K,0. Apply the remaining 120 Ib N/A in
two or more sidedressings, one of which should be at 4 weeks.
103 Apply all of the P20,, 30% of the KO, and 30 Ib N/A in a preplant or at-planting application. Four
weeks after planting sidedress the remaining 70% of the K20. Apply the remaining 150 Ib N/A in
two or more sidedressings, one of which should be at 4 weeks.
104 Apply all of the P205, 30% of the K,0, and 30 Ib N/A in a preplant or at-planting application. Four
weeks after planting sidedress the remaining 70% of the K,0. Apply the remaining 180 Ib N/A in
three or more sidedressings, one of which should be at 4 weeks.
105 Apply all of the P205, 30% of the K20, and 30 Ib N/A in a preplant or at-planting application. Four
weeks after planting sidedress the remaining 70% of the K,0. Apply the remaining 210 Ib N/A in
three or more sidedressings, one of which should be at 4 weeks.
106 Apply all of the P0O, and 30% of the K,2 and N in a preplant or at-planting application. Topdress
or sidedress the remaining 70% of the K,0 and N. For small grains grown for grain, topdress
during late January or early February. For grain sorghum or forage sorghum, sidedress before
plants are too tall to cultivate or approximately four weeks after planting.
107 Apply all of the P20, and 30% of the K20 and N in a preplant or at-planting application. Apply the
remaining 70% of the K20 and N in one sidedressing.
108 Application of 20 to 30 Ib N/A may give vegetative response but is unlikely to increase harvested
yield.
109 If peanuts are grown for seed or if they are Virginia type, regardless of soil test, apply gypsum in
a band over the potential pegging zone at early flower. Apply 400 Ib gypsum/A for runner types
and 800 Ib gypsum/A for Virginia types. Double these rates if broadcasting granular or
phosphogypsum (bulk wet). For peanuts not grown for seed, apply gypsum as recommended
above only if the calcium soil-test level is below 250 ppm Ca.
110 Apply 50% of the fertilizer at or before transplanting and the other half within 3 weeks of
transplanting.
111 Apply 30 Ib N/A, 50% of the K20, and all of the P0O, fertilizer in a preplant or at-planting
application. Apply 50 Ib N/A and the remaining KO after the first grazing period. Apply an
additional 50 Ib N/A after each subsequent grazing period.
112 When planting a prepared seed bed, apply 30 Ib N/A, 50% of the K20, and all of the P205 fertilizer
in a preplant or at-planting application. Apply 50 Ib N/A and the remaining K20 after the first
grazing period. Apply an additional 50 Ib N/A after each subsequent grazing period.

For overseeding established perennial grasses with cool season annual grasses, apply 50 Ib
N/A plus all P2Oj and K,0 after emergence. Apply an additional 50 Ib N/A after each subsequent
grazing period.
115 Apply all of the P0O, and 50% of the K,0 fertilizer in late fall. Apply the remaining KO in early
spring. If legumes are planted in combination with oats, rye, wheat, and/or ryegrass, apply 30 Ib
N/A in a preplant or at-planting application plus one additional 50 Ib N/A application after the
grass is well established.

116 Apply all of the P20, and 50% of the K,O fertilizer in late fall. Apply the remaining K,0 in early
spring.









118 Apply 0.75 Ib boron/A in the fertilizer or 0.5 Ib boron/A as a foliar spray with the first fungicide
application.

120 Fertilizer should contain 15 to 20 Ib sulfur/A. Apply as a sulfate (eg. gypsum, ammonium sulfate,
magnesium sulfate, potassium sulfate, potassium magnesium sulfate), since elemental sulfur will
react too slowly to supply the sulfur needs of the current crop.
121 Apply all of the P,O, and K,O in spring or early summer when seedlings or regrowth are 3 to 4
inches tall. Species included are aeschynomene, alyce clover, desmodiums, hairy indigo, perennial
peanut, and other tropical legumes.
122 Species included are all true clovers (white, red, arrowleaf, crimson, subterranean), vetches,
lupines, and sweet clover.
123 Apply all of the P2O, and 50% of the K,O fertilizer in late fall. Apply the remaining K0, in early
spring. If the alfalfa is mechanically harvested rather than grazed, apply an additional 30 Ib P20O/A
and 60 Ib K,0/A after each harvest. An additional application of 100 Ib K,0/A in June or July
may increase summer survival of alfalfa. Apply 3 Ib boron/A per year to alfalfa in three 1 Ib/A
applications. Copper and zinc fertilizer may be needed if soil pH is above 6.5.

The lime requirement shown above is adequate for established alfalfa. However, if the alfalfa
has not yet been planted, apply and incorporate one ton of lime/A if the soil pH is below 6.6.
Lime is especially important for establishment of alfalfa. It is not practical to incorporate lime once
the alfalfa is planted.

124 IFAS recommendations emphasize efficient fertilizer use without losses of yield or of crop quality.
Efficient fertilizer use results in high production with minimum impact to our environment. Since
fertilizer use and management are only two aspects of crop production, growers are encouraged
to consider IFAS recommendations in light of their entire management strategy, including financial
considerations.
125 Grass species included are bermuda, star, limpo, and digit.
126 For new plantings, apply only 100 Ib N/A and split as follows: apply 30 Ib N/A, all of the P20,,
and 50% of the KO as soon as plants have emerged. Apply the remaining K,0 and 70 Ib N/A
30 to 50 days later.

For grazed, established stands, apply 80 Ib N/A, all of the P2O,, and 50% of the K0 in early
spring. Apply the remaining N and K,2 at mid-season. Under intensive management in central
and south Florida, up to 200 Ib N/A may be economically viable for stargrass and bermudagrass.
In that situation, apply 80 Ib N, all of the P2O, and KO in early spring, follow with 50 Ib N/A in
mid-season, and 70 Ib N/A and the other 50% KO in mid to late September.

If cutting for hay or silage, apply 80 Ib N/A, all of the PO, and KO in early spring. Apply an
additional 80 Ib N/A and 40 Ib KO/A after each cutting.
127 Apply all of the P20,, 50% of the K20, and 40 Ib N/A at planting. Topdress the remaining N and
KO in late January. On land which lacks clayey soil within the top 6 to 8 inches of the surface,
apply 5 to 10 Ib sulfate-sulfur/A at planting and 10 Ib sulfate-sulfur/A in the topdressing. Wettable
or other elemental forms of sulfur will react too slowly to supply the sulfur needs of the current
crop. On flatwoods soils with pH above 6.1, apply 10 Ib manganese/A. On better-drained sands
with pH above 6.5, apply 6 to 10 Ib manganese/A.










128 The recommended rates of fertilizer are sufficient to produce soybean yields in the 60 bu/A
range. If yields from this field have never exceeded 40 bu/A under current management, reduce
P20, and K,0 recommendations by 20 Ib/A. If yields from this field have never exceeded 25 bu/A,
reduce P,20 and KO recommendations by 40 Ib/A. Often this adjustment will mean that you will
achieve your yield potential without any P or K fertilizer additions.
129 These recommendations are made assuming adequate soil moisture will be available either from
rainfall or irrigation. In south Florida, lack of adequate rainfall during the cool season frequently
causes stand failure or limits growth. Under non-irrigated conditions in south Florida, the
probability of inadequate moisture is high and the likelihood that the crop will benefit from applied
fertilizer is low.

131 Fertilization Management Notes for Bahiagrass Pastures

For new plantings, apply only 100 Ib N/A split as follows: apply 30 Ib N/A, all of the P2O0, and
50% of the K,0 as soon as plants have emerged. Apply the remaining K,0 and 70 Ib N/A 30 to
50 days later.

For established stands of bahiagrass, apply all of the fertilizer in the early spring to maximize
much-needed spring forage. Bahiagrass is a very efficient forager and recovers nutrients from
deeper in the soil profile that other popular forage grasses so danger of leaching losses is low.
Three fertilization options are presented below. Choose the option which most closely fits your
fertilizer budget, management objectives, and land capability.

High-Nitrogen Option Apply 160 Ib N/A and the soil-test-based recommended rates of P20, and
K20 for each of your pastures. The fertilization rates suggested in this option are high enough
to allow bahiagrass pasture to achieve well above average production. Management and
environmental factors will determine how much of the potential production is achieved and how
much of the forage is utilized.

Medium-Nitrogen Option Apply around 100 Ib N/A this year. At that level of N fertilization, P and
K may be limiting if your soil tested low in these nutrients. Apply 25 Ib P0O,/A if your soil tested
low in P and none if it tested medium. Apply 50 Ib K20/A if your soil tested low in K and none
if it tested medium. Re-test your soil every second or third year to verify P and K levels. If you
plan to make a late-season cutting of hay, apply 80 Ib N/A between August 1 and 15 (about 6
weeks before the growing season ends).

Low-Nitrogen Option (for Grazed Pastures only) Apply around 50 Ib N/A this year, recognizing
that N will be the limiting nutrient. Thus, do not apply P or K. If you follow this practice of
applying only N to your pasture for more than one year, apply the P and K recommended by soil
tests every third or fourth year to avoid excessive depletion of those nutrients. Do not use this
option if you cut hay since nutrient removal by hay is much greater than by grazing animals.











Table 14b. Footnotes used with vegetable crops.

250 Indicated fertilizer amounts, and the nutrients already in the soil, will satisfy the crop nutrient
requirement for this cropping season. Fertilizer and water management are linked. Maximum
fertilizer efficiency is achieved only with close attention to water management. Supply only enough
irrigation water to satisfy crop requirements. Excess irrigation may result in leaching of N and K,
creating possible plant deficiencies.

For subsurface irrigation, maintain a constant water table between 15 and 18 inches below the top
of the bed.

On soils that have not been in vegetable production within the past 20 years, or where
micronutrients are known to be deficient, apply 5 Ibs of Mn, 3 Ib Zn, 4 Ib Fe, 3 Ib Cu, and 1.5 Ib
B/A. Use soil testing to monitor micronutrient status every 2 years. When deciding about
micronutrient applications, consider micronutrients added to the crop via fungicides. Some
micronutrients can build up in the soil avoid micronutrient toxicity.
251 Fertilizer should be applied in split applications to reduce leaching losses and lessen danger of
fertilizer burn. Broadcast all P20, and micronutrients, if any, and 25 to 50% of the N and K20 in
the bed at planting. Apply remaining N and K20 in sidedress bands during the early part of the
growing season.

In cold soil or after fumigation, apply 20 to 25% of the recommended N in the nitrate form.

Additional, supplemental sidedress applications of 30 Ib N/A and 20 Ib K20/A should be applied
only after rainfall/irrigation amounts exceed 3 inches within a 3-day period or exceeds 4 inches
within a 7-day period. Avoid mechanical damage to plants when applying fertilizers.

252 The amounts suggested are generally sufficient for 2 or 3 crops in succession.

253 Where scab-resistant cultivars are grown, a pH between 6.0 and 6.5 is optimum. Where
scab-susceptible cultivars are grown, the pH should be below 5.2 or above 7.2.

350 Supply 25 to 50% of the N in the nitrate form if soils were treated with multi-purpose fumigants.

351 For subsurface irrigation, incorporate 10 to 20% of the N and K,0, plus all of the P20, and
micronutrients, if any, into the bed. Apply the remainder of the N and K,0 one inch deep in one
or more bands about 6 to 10 inches from the plants.

For drip irrigation, incorporate 20 to 40% of the N and K,0 and all of the P20, and micronutrients,
if any, into the bed. Apply the remainder of the N and KO periodically through drip tubes
according to the rate of crop growth.

For management systems where both seep and drip irrigation are being used, apply no more
than 20% of the N and KO, plus all of the P205 and micronutrients, if any, into the bed. Apply
the remainder of the N and K,2 periodically through drip tubes according to the rate of crop
growth.

For overhead irrigation, incorporate all of the N, K,0, P2O,, and micronutrients, if any, into the bed
prior to installation of the plastic mulch.

352 Amounts suggested are for the first crop. Squash and cucumber following other crops on the
same mulch may not need additional fertilizer. If fertilizer is needed for the second crop, apply
fertilizer using a liquid-injection wheel or via drip irrigation.











353 From 25 to 30% of the N may be supplied from slow-release N sources, such as sulfur-coated
urea or isobutylidene-diurea (IBDU).
354 Transplants may benefit from application of a dilute, soluble starter fertilizer, especially at cool soil
temperatures.

355 Broadcast all the P20, and micronutrients, if any, and 25% of the N and K,0 into the bed. Place
the remaining N and KO in a band 2 to 3 inches deep in the center of the bed.



Table 14c. Footnotes used with citrus and blueberries.
401 Except for pH, lime requirement, and in some instances P, soil-test results are generally not used
as a basis for fertilization of perennial fruit and nut crops in Florida. Program fertilization is
practiced, and plant-tissue testing may be helpful for certain crops.
402 For specific citrus fertilization recommendations, refer to IFAS bulletin 536 D, "Recommended
Fertilizers and Nutritional Sprays for Citrus.' For assistance with interpretation, contact your county
Extension office.
403 A general recommendation for citrus establishment follows: Use dolomitic limestone to raise soil
pH above 6.0, if necessary. During the first year make four or five applications of 0.08 Ib N, 0.02
Ib P203, and 0.08 Ib K,0 per tree. Double this rate in the second year. In the 3rd through the 6th
years, make three fertilizer applications, each containing 0.08 Ib N, 0.02 Ib P20, and 0.08 Ib K,0
per year of tree age. Example: 0.32 Ib N per tree three times in the fourth year after planting.
Magnesium, manganese, copper, and boron will also be needed on land not previously fertilized
with these nutrients.
404 Generally oranges require 0.4 Ib of N/year/box of fruit and grapefruit require 0.3 Ib N/box of fruit
up to a maximum of 250 Ib N/A. The general K,0 requirement is the same as the N requirement.
If the P soil-test level is high or very high, no P fertilizer is recommended; otherwise apply 0.2 Ib
P203/box of fruit every fourth year. Leaf tissue analysis is recommended for guiding fertilization,
and is especially helpful in determining the need for micronutrient fertilization.
405 Long-term liming experiments have demonstrated consistent and significant citrus yield increases
up to a soil pH of 7.0, even where Cu toxicity is not a problem. However, maintenance of soil pH
levels in excess of 7.0 is not generally recommended.
408 Soil pH should be between 4.0 and 5.2 for Florida blueberries. Iron deficiency chlorosis,
characterized by interveinal yellowing in young leaves, is often the result of soil pH above 5.2. To
lower the soil pH, apply agricultural grade sulfur or aluminum sulfate to the soil. If soil pH is within
the proper range and plants are chlorotic, apply soluble iron to the plants.


Table 14d. Footnotes used with turfgrasses.
501 For details on fertilization obtain Soil Science fact sheet SL-21, "General Recommendations for
Fertilization of Turf-Grasses on Florida Soils," from your county Extension agent.

These rates are for normal, healthy lawns. Double the rates for high maintenance turf.

Divide annual rates into 2 to 8 applications depending on location and management levels. Apply
no more than 1.0 Ib N/1000 sq. ft. per application.
504 Standard fertilizer recommendations for growing high quality turf are not given here. Management
level and local conditions greatly influence fertilizer input. Contact your county Extension agent
if a recommendation is required.








Table 14e. Footnotes used with ornamentals in commercial production and ornamentals in the landscape.

650 Indicated fertilizer amounts, coupled with nutrients already in the soil, will satisfy the crop-nutrient
requirement for this growing season. Fertilizer and water management are linked. Maximum
fertilizer efficiency is achieved only with close attention to water management. Supply only enough
irrigation water to satisfy plant requirements and minimize leaching conditions.
651 Broadcast P20, either in one application or at half the recommended amount in each of two
applications during the growing season. To minimize leaching losses, broadcast N and K,0 in
small increments throughout the growing season. Schedule one application every 4 to 6 weeks
(six to eight times per growing season), adding 10 to 15% of the recommended amount of N and
K,0 at each application. To insure equal coverage when fertilizer rates are small, blend all
compatible fertilizers or add needed nutrients through the irrigation system.
652 Additional supplemental broadcast applications of 10% of the recommended amounts of N and
K20 should be applied only after rainfall amounts exceed 3 inches within a 3-day period or exceed
4 inches within a 7-day period. Avoid mechanical damage to plants when applying fertilizers.
653 Established trees (more than three to five years since transplanting) do not need routine
fertilization.

For recently-planted trees, broadcast fertilizer within a diameter of 1.5 times the dripline diameter.
654 Broadcast P20, either in one application or as half the recommended amount in each of two
applications during the growing season. To minimize leaching losses, broadcast N and K20 in
small increments throughout the growing season. Schedule one application every 12 weeks
(three times per growing season), adding 33% of the recommended amount of N and K,0 at each
application. To insure equal coverage when fertilizer rates are small, blend all compatible fertilizers
or add needed nutrients through the irrigation system.



Table 14f. Footnotes used with commercial forestry production.
701 Based upon subsoil pH, this pine plantation is likely to benefit from P fertilization. After 1 year of
growth, N and P fertilizers in combination occasionally produce increased tree growth. If N fertilizer
is added alone to young plantations, undesirable weed competition may result with little increased
pine growth.
702 Fertilizer addition is not recommended. Increased pine growth is not expected from fertilizer
addition because soil-test results predict that the trees will obtain adequate nutrition from the soil
alone.
703 No fertilizer is recommended for pines growing on soils in CRIFF Soil Groups D, E, F, and G.
704 Fertilizer recommendations for pine plantations older than 8 years are not based upon soil testing.

705 For detailed recommendations, contact CRIFF coordinator in Gainesville (904-392-1850).








Table 14g. Footnotes used with landscapes, lawns, and vegetable gardens.
901 Sidedress every 3 weeks or after heavy rains. On each 100 sq. ft. use 1/4 cup ammonium nitrate
mixed with 1/4 cup muriate of potash, or use 2 cups of 6-8-8 fertilizer.
902 Apply 1 Ib sulfur/100 sq. ft. to lower soil pH. Also, apply 1 oz/100 sq. ft. of a complete
micronutrient mix, or use a complete fertilizer which contains micronutrients.
903 This report does not contain fertilization recommendations. Pamphlets on fertilization of lawns,
vegetable gardens, dooryard fruits, and ornamentals are available from your county Extension
service office.
908 Since no crop code was specified, fertilizer and lime recommendations have been omitted.
Contact your Extension agent for specific recommendations.








--- SECTION 4 ---


Electrical Conductivity Interpretations

Assumptions and Mode of Calculation

Soluble-salt problems in Florida arise from two common sources: saltwater effects
in coastal areas, including saltwater intrusion of wellfields (where the predominant ions are
sodium and chloride), and salt effects due to over fertilization (where the predominant
highly-soluble ions are potassium, chloride, ammonium, nitrate, and sulfate). Historically,
the ESTL has reported soluble salt values for Florida soils in terms of ppm, using a dry-soil
basis. Though this approach works poorly at best in much of the world, it has served
Florida agriculture well, because of the uniformly sandy nature of Florida's mineral surface
soils. However, because of its infrequent use elsewhere, the ppm dry-soil convention
isolates Florida's growers and ag-industry personnel from the large and steadily growing
body of salinity literature world-wide. For this reason, the ESTL has recently converted
its soluble salts index to a saturation-extract electrical conductivity (EC) basis.

Excessive soluble-salt effects on plant growth can be classified into osmotic (related
to total salt levels) and specific-ion effects. The latter include the effects of ions which are
particularly harmful to sensitive species, such as sodium, chloride, boron, and fluoride. This
effect is generally less severe than the osmotic effect. Osmotic effects are commonly
inferred from the EC of a soil extract, with the EC being proportional to the soluble-salt
concentration and generally negatively correlated with plant-growth response.

The saturation extract has been adopted as the soil water-content standard for such
soluble-salt measurements. In general, the water content of soil following drainage of free
water from either over-irrigation or a heavy rain (the so-called field capacity) is about 1/2
that at saturation. Similarly, the water content at the crop's permanent wilting point
(from which the crop will not recover even if the soil is rewetted) is 1/2 to 1/3 that at field
capacity. Use of water contents higher than saturation introduces the risk of solubilizing
slightly-soluble salts such as lime and gypsum, and of significantly changing the
soluble-cation composition due to exchange of ions such as calcium and magnesium, for ions
such as potassium, sodium, and ammonium, as the soil solution is diluted during extraction.
For a reasonably rapid and reproducible estimation of soluble salts for extremely sandy soils
such as are common to Florida, however, the analyst often has no choice but to use a
higher water content for extraction of soluble salts.

The water content used at the ESTL for soluble-salts estimation has been 2:1
water:soil, or 200%. It has been determined (R. D. Rhue, unpublished data), for a group
of 100 Florida mineral surface soils, that the average water content (air-dry basis) at
saturation was 26% w/w. Hence, the conversion factor between EC as measured, and EC
of a typical saturation extract, is approximately 8 (200% divided by 26% = 7.7). This value,
the measured EC in dS/m x 8 or in mmho/cm x 8, is termed the salt index for the soil
sample in question. The salt index will vary as rainfall or crop uptake removes soluble
salts from the crop-root zone, or as fertilizer salts or salts from irrigation water are added
to the soil. Salt index also normally varies both across the crop bed (depending upon
fertilizer placement and upon former water-movement patterns) and with depth beneath the
bed. Current wisdom holds that the crop responds to the weighted-average salinity (EC)
within the root zone though this is likely inaccurate for banded fertilizer placement. If
sufficient low-salinity water is maintained in the root zone for plant evapotranspiration
needs, many plants (barring specific-ion effects) will grow quite well despite the presence
of moderately- to highly-saline water within normal rooting depths.








Modification for Soils Containing Gypsum or Lime


Because of the high water content used for soluble-salts estimation at the ESTL, the
client must be aware of possible misinformation if the soil sample also contains gypsum or
lime. Approximately 25% of the soil samples received by the ESTL in recent years have
evidenced pH values high enough to suggest the presence of lime. Even for soils not
recently limed, the continued use of irrigation water from limestone aquifers may have
resulted in the accumulation of free carbonates in frequently-wetted portions of the profile.
Lime is soluble to the extent of approximately 0.1 dS/m (mmho/cm) at pH 8, and
progressively more soluble at lowered pH values. Because of lime dissolved at 200% water
content (a 2:1 water:soil ratio) which would not be in solution at 26% water content
(saturation), a correction factor of 1.0 should be subtracted from the salt index for soil
samples known to contain free carbonates in addition to their soluble salts.

Gypsum is soluble to the extent of 2.0 dS/m (mmho/cm), with its solubility
essentially independent of pH. The 2:1 water:soil ratio is totally inappropriate for soils
containing gypsum. A large (e.g. 100-200g) sample of such soil should instead be extracted
under pressure or vacuum at the saturation water content (25-30% for typical Florida
sands), and 2.0 subtracted from the resultant EC value to obtain an estimate of the
contribution of non-gypsum salts to the sample's salinity. This is not within the scope of
services routinely provided by the ESTL.

Inter-Conversion from Former Soluble-Salts Values

Conversion from former ESTL soluble-salts values (expressed on the basis of ppm,
air-dry-soil) to saturation-extract EC (salt index) values requires knowledge of the types of
salts being dealt with. For coastal areas in which the salts are primarily of marine origin,
an average equivalent weight for the salts present would be approximately 60 mg/meq. For
primarily fertilizer-salt mixtures, however, as was apparently assumed by early formulators
of the former ESTL approach, an equivalent-weight value of approximately 70 mg/meq is
more appropriate instead. Scientists at the U.S. Salinity Laboratory (Richards, 1954)
assumed an equivalent weight of 64 mg/meq for "typical" western-U.S. irrigation waters.

Inter-conversion of the two types of values can be calculated as follows:

Salt index (dS/m, or mmho/cm, saturation-extract basis) =

Soluble Salts (ppm soil, or mg/kg, air-dry basis) 1 kg 100% 1 dS/M
_________________________ x x x
Equivalent Weight of Salt (mg/meq) 1L 26% 10 meq/L

Simplifying the above expression, Salt index = Soluble salts x 0.0055

To convert from salt index values back to soluble salts,

Soluble Salts (ppm soil, air-dry basis) =

10 meq/L 26% 1 L 70 mg/meq
Salt index (dS/m, or mmho/cm) x x x x
1 dS/m 100% 1 kg 1 mg/kg per ppm

Simplifying this equation results in: Soluble salts = Salt index x 180








--- SECTION 4 ---


Electrical Conductivity Interpretations

Assumptions and Mode of Calculation

Soluble-salt problems in Florida arise from two common sources: saltwater effects
in coastal areas, including saltwater intrusion of wellfields (where the predominant ions are
sodium and chloride), and salt effects due to over fertilization (where the predominant
highly-soluble ions are potassium, chloride, ammonium, nitrate, and sulfate). Historically,
the ESTL has reported soluble salt values for Florida soils in terms of ppm, using a dry-soil
basis. Though this approach works poorly at best in much of the world, it has served
Florida agriculture well, because of the uniformly sandy nature of Florida's mineral surface
soils. However, because of its infrequent use elsewhere, the ppm dry-soil convention
isolates Florida's growers and ag-industry personnel from the large and steadily growing
body of salinity literature world-wide. For this reason, the ESTL has recently converted
its soluble salts index to a saturation-extract electrical conductivity (EC) basis.

Excessive soluble-salt effects on plant growth can be classified into osmotic (related
to total salt levels) and specific-ion effects. The latter include the effects of ions which are
particularly harmful to sensitive species, such as sodium, chloride, boron, and fluoride. This
effect is generally less severe than the osmotic effect. Osmotic effects are commonly
inferred from the EC of a soil extract, with the EC being proportional to the soluble-salt
concentration and generally negatively correlated with plant-growth response.

The saturation extract has been adopted as the soil water-content standard for such
soluble-salt measurements. In general, the water content of soil following drainage of free
water from either over-irrigation or a heavy rain (the so-called field capacity) is about 1/2
that at saturation. Similarly, the water content at the crop's permanent wilting point
(from which the crop will not recover even if the soil is rewetted) is 1/2 to 1/3 that at field
capacity. Use of water contents higher than saturation introduces the risk of solubilizing
slightly-soluble salts such as lime and gypsum, and of significantly changing the
soluble-cation composition due to exchange of ions such as calcium and magnesium, for ions
such as potassium, sodium, and ammonium, as the soil solution is diluted during extraction.
For a reasonably rapid and reproducible estimation of soluble salts for extremely sandy soils
such as are common to Florida, however, the analyst often has no choice but to use a
higher water content for extraction of soluble salts.

The water content used at the ESTL for soluble-salts estimation has been 2:1
water:soil, or 200%. It has been determined (R. D. Rhue, unpublished data), for a group
of 100 Florida mineral surface soils, that the average water content (air-dry basis) at
saturation was 26% w/w. Hence, the conversion factor between EC as measured, and EC
of a typical saturation extract, is approximately 8 (200% divided by 26% = 7.7). This value,
the measured EC in dS/m x 8 or in mmho/cm x 8, is termed the salt index for the soil
sample in question. The salt index will vary as rainfall or crop uptake removes soluble
salts from the crop-root zone, or as fertilizer salts or salts from irrigation water are added
to the soil. Salt index also normally varies both across the crop bed (depending upon
fertilizer placement and upon former water-movement patterns) and with depth beneath the
bed. Current wisdom holds that the crop responds to the weighted-average salinity (EC)
within the root zone though this is likely inaccurate for banded fertilizer placement. If
sufficient low-salinity water is maintained in the root zone for plant evapotranspiration
needs, many plants (barring specific-ion effects) will grow quite well despite the presence
of moderately- to highly-saline water within normal rooting depths.








Though an equivalent weight of 70 mg/meq appears to have been used for earlier ESTL
inter-conversions, the lowered equivalent weight for salts almost exclusively of marine origin
should be kept in mind when working with former ESTL values in coastal areas. For some
interpretations from the data, this is a significant (nearly 20% difference) distinction.

Salt-Index Ranges for Selected Commodities

In using the following tables, please note that crops are grouped from most-sensitive to
least-sensitive within a given crop type. In addition to the direct relative-yield values for
the crop (comprising all but the two right-hand columns in the table), there is also provided
a) a salinity-threshold value below which no salinity effects are observed; and b) a
percentage-yields decrease per unit salt-index increase for salt-index values above the
salinity-threshold value. These are provided for more precise interpretation of the data,
and also for ease of data entry into computer-based yield predictors if the client is using
such.






Table 15. Relative yields of selected field and forage crops at selected salt-index levels (Carter, 1981).


Relative yield (%) at salt-index values of:


Plant Name Scientific Name


Moderately Sensitive


Alfalfa Medicago sativa
Clover Trifolium spp.
Corn, forage Zea mays
Flax Vinum usitatissimum
Lovegrass Eragroslis spp.
Peanut Arachis hypogaca
Rice, Paddy Oryza sativa
Sesbania Sesbania exaltata
Trefoil, big Lotus uliginosus
Vetch, common Vicia sativa


1 2 a 4 6



100 100 93 85 71
100 94 82 70 40
00 99 91 84 69
100 96 84 72 48
100 100 92 83 66
100 100 100 77 20
100 100 100 88 63
100 100 95 88 74
100 100 87 68 30
100 100 100 89 67


8 10 12 16 20 24


56 42
22 0
54 39
24 0
49 32
0
39 15
60 47
0
44 22


(Also in this group: bentgrass, canarygrass, millet, sweet clover, timothy)

Moderately tolerant


Barley, forage Hordeum vulgare 100
Clover, berseem Trifolium alexandrinium 100
Fescue Festuca clatior 100
Hardinggrass Phalaris tuberosa 100
Orchardgrass Dactylis glomerata 100
Ryegrass, Lolium perene 100
Perennial
Safflower Carthamus tinctorius 100
Sorghum Sorghum bicolor 100
Soybean Glycine max 100
Sudan grass Sorghum sudanese 100
Sugarcane Saccharum spp. 100
Trefoil, Lotus corniculatus 100
birdsfoot tenuifolium


100 100 100 100
97 91 86 74
100 100 99 89
100 100 100 89
97 91 84 72
100 100 100 97


86 72
63 51
78 68
74 59
60 47
82 67


100 100 100 100 90 80
100 100 100 90 78 63
100 100 100 80 40 0
100 99 95 84 78 69
98 92 86 75 63 51
100 100 100 90 70 50


Salinity-
effect
threshold
(ds/m)


% Yield
decrease
per
subsequent
dS/m
increase


7.3
12.0
7.4
12.0
8.5
28.6
12.2
7.0
18.9
11.1






Table 15. (continued)


Relative yield (%) at salt-index values of


% Yield
decrease
Salinity- per
effect subsequent
threshold dS/m


Plant Name Scientific Name 1 2 3 4 6 8 10 12 16 20 24 (ds/m)

Wheat Triticum aestivum 100 100 100 100 100 86 71 57 29 6.0
Wildrye, beardless Elymus triticoides 100 100 98 92 80 68 56 44 20 2.7

(Also in this group: bromegrass, dallisgrass, milkvetch, oats, rhodesgrass, rye [hay], wheatgrass [slender, western], wildrye [Canada].)


increase

7.1
6.0


Tolerant

Barley, grain Hordeum vulgare 100 100 100 90 80 60 40 20
Bermudagrass Cyneden dactylon 100 100 93 80 67 42 16 0
o Cotton Gossypium spp. 100 100 98 88 78 57 36 16
Wheatgrass, Agopyron desertorum 98 90 82 74 66 50 34 18
crested
Wheatgrass, Agopyron cristatum 100 100 97 83 69 41 14 0
fairway
Wheatgrass, tall Agropyron elongatum 100 100 98 89 81 64 47 31

(Also in this group: butall alkaligrass, rescuegrass, saltgrass, wildrye [altai, Russian].)


1




Table 16. Relative yields of selected vegetable crops at selected salt-index values (Carter, 1981).


Relative yield (%) at salt-index values of:


Plant Name


Sensitive
Bean
Carrot
Celery
Okra
Onion
Strawberry


Scientific Name 1 2 3 4 6 8 10 12 16 20 24


Phaseolus vulgaris 100 81 62 43 6
Daucus carota 100 86 72 58 30 1
Apium graveoleus 100 90 75
Abelmoschus esculentus 100 90
Allium cepa 100 87 71 55 23 0
Fragaria spp. 100 67 33 0


Moderately Sensitive


Broadbean
Cauliflower
Cabbage

Corn, sweet
o Cucumber
Lettuce
Muskmelon
Pea
Pepper
Potato
Radish
Spinach
Squash
Sweet potato
Tomato


Vicia faba 100 96 87 77 58 38 19 0
Brassica oleracea 100 100 93 85
Brassica oleracea 100 98 88 79 59 40 20 1
var. Capitata
Zea mays 100 96 84 72 48 24 0
Cucumis sativus 100 100 94 81 55 29 3
Latuca sativa 100 91 78 65 39 13
Cucumis melo 100 100 95 80
Pisum sativum L. 100 100 90
Capsicum annum 100 93 79 65 37 8
Solanum tuberosum 100 96 84 72 48 24 0
Raphanus sativus 100 90 77 64 38 12
Spinacia oleracea 100 100 92 85 70 55 39 24
Cucurbita maxima 100 100 90 74
Ipomoea batatas 100 95 84 73 51 29 7
Lycopersicon esculentum 100 100 95 85 65 46 26 6


Moderately tolerant


Beta vulgaris
Brassica oleracea
var. capitata
Brassica campestris


100 100 100 100 82 64 46 29 0
100 100 98 89 71 52 34 16

100 100 100 100 100



100 100 100 100 100 94 82 71 47 24


Salinity-
effect
threshold
(ds/m)


% Yield
decrease
per
subsequent
dS/m
increase


18.9
14.1


16.1
33.3


9.6

9.7

12.0
13.0
13.0


14.1
12.0
13.0
7.6

11.0
9.9


Beet, garden
Broccoli

Kale


Tolerant


Sugarbeet Beta vulgaris


0 7.0 5.9





Table 17. Relative yields of selected fruit crops at selected salt-index values (Carter, 1981).


Relative yield (%) at salt-index values of:


Scientific Name


1 2 3 14 8 10 12 16 20


% Yield
decrease
Salinity- per
effect subsequent
threshold dS/m
(ds/m) increase


Avocado Persea americana
Blackberry Rubus spp.
Grapefruit Citrus paradisi
Lemon Citrus limon
Orange Citrus sinensis
Peach Prunus persica
Pineapple guava Feijoa sellowiana
Raspberry Rubus idaeus


70
67 44 0
81 65 32 0
75
79 63 32 0
73 52 10 0
34 0


Moderately sensitive


SGrape
-


Vitis spp.


100 95 86 76 57 38 18


Moderately tolerant


Ficus carica
Punica granatum


100 100 100 100 85
100 100 100 100 85


(Also in this group: lime [rangpur), mandarin [Cleopatra]).

Tolerant


Pheonis dactylifera
Carissa grandiflora


100 93 86 78
100 100 82


71 57 42


Plant Name


Sensitive


Fig
Pomegranate


22.2
16.1

15.9
18.8


Date
Natal Plum





Table 18. Relative yields of selected ornamentals at selected salt-index values (Carter, 1981).


Relative yield (%) at salt-index values of:


Plant Name Scientific Name


1 2 a 4 6 8 19 12 16 20 24


% Yield
decrease
Salinity- per
effect subsequent
threshold dS/m
(ds/m) increase


Algerian ivy Hedera canariensis
Burford holly Olex comuta
Heavenly bamboo Nandina domestic
Hibiscus Hibiscus rosa-sinensis
Brilliant


Pittosporum
Rose
Star jasmine


Pittosporum tobira
Rose spp.
Trachelospermum
jasminoides


81 62 35
82 59 36 0
88 75 61 34 7
86 72 58 28 0


100 89 79 69 50 30
100 74 36 0
100 83 61 40 0


(Also in this group: burnet)

S Moderately sensitive


Thuja orientalis
Callistemon viminalis
Buxux microphylla
var. japonica
Dodonaea viscosa
var. Atropurpurea
Juniperus chinensis
Lantana camera
Nerium oleander
Pyracantha braperi
Elaeagnus pungens
Ligustrum lucidum
Viburnum spp.
Xylosma senticosa


100 100
100 94
100 96


91 81 62 43 24
85 77 59 41
86 76 54 32 11


100 94 86 77 59 42 25


100 91
100 92
100 100
100 99
100 95
100 94
100 90
100 94


81 72 54 36 18 0
82 72 51 30 9
93 86 72 58 44 30
90 81 62 43 24 6
87 78 59 41 23 16
85 75 56 36 16 0
73 58 32 10
81 67 40 14


Sensitive


Arborvitae
Bottlebrush
Boxwood

Dodonaea

Juniper
Lantana
Oleander
Pyracantha
Silverberry
Texas privet
Viburnum
Xylosma





Table 18. (continued)


Relative yield (%) at salt-index values of


% Yield
decrease
Salinity- per
effect subsequent
threshold dS/m
(ds/m) increase


Scientific Name


Moderately tolerant


Alkali sacaton
Dracaena
Euonymus


Tolerant


Bougainvillea
Rosemary


Sporobolus airoides
Dracaena endivisa
Euonymus japonica



Bougainvillea spectabilis
Rosmarinum lockwoodii


1 2 3 4 6 8 10 12 16 20 24



100 100 0
100 100 100 94 76 58 40 22 0
100 77 27 0


100 100 100
100 85


Plant Name








--- SECTION 5 ---


Interpretation of Water-Test Results

Household Uses

A detailed interpretation of analyses conducted on home water is printed directly on the
water report form which can be found in appendix A of this publication. An extended
discussion is included here to emphasize certain points.

1. Water Hardness
Originally, the hardness of a water was understood to be a measure of the capacity of
that water for precipitating soap. Soap is precipitated chiefly by the Ca and Mg ions
commonly present in water, but also may be precipitated by other polyvalent ions. Because
only Ca and Mg are commonly present in significant concentrations in natural waters,
hardness is defined as a characteristic of water which represents the total concentrations
of Ca and Mg ions expressed as CaCO, (Rand, Greenberg, and Taras, 1976).

(ppm Ca X 2.5) + (ppm Mg X 4.1) = ppm hardness,

where the factors 2.5 and 4.1 are conversions for ppm Ca and Mg,
respectively, to ppm of CaCO,.

Table 19. Interpretation of the hardness scale for household water.
Rating Hardness (ppm)

Soft 0 to 17
Relatively Soft 18 to 50
Moderately Soft 51 to 120
Hard 121 to 170
Very Hard >170

2. Iron
High levels of Fe in home water can impart a metallic taste to water and can stain
clothes and plumbing. Staining can be caused by as little as 0.3 ppm Fe.

3. pH
Acid water is corrosive and, therefore, water should be on the alkaline side of the pH
range to prevent damage to metal parts of the water system.

4. Electrical Conductivity, Sodium, and Chlorides
Although all salts dissolved in water contribute to its electrical conductivity, high values
of Na and Cl are usually associated with salt water intrusion, which is a problem for many
wells in coastal areas. Water containing 0.4 to 0.6 dS/m tastes "salty" to most people.
There is no economical means at present for removing salts from water supplies.








--- SECTION 5 ---


Interpretation of Water-Test Results

Household Uses

A detailed interpretation of analyses conducted on home water is printed directly on the
water report form which can be found in appendix A of this publication. An extended
discussion is included here to emphasize certain points.

1. Water Hardness
Originally, the hardness of a water was understood to be a measure of the capacity of
that water for precipitating soap. Soap is precipitated chiefly by the Ca and Mg ions
commonly present in water, but also may be precipitated by other polyvalent ions. Because
only Ca and Mg are commonly present in significant concentrations in natural waters,
hardness is defined as a characteristic of water which represents the total concentrations
of Ca and Mg ions expressed as CaCO, (Rand, Greenberg, and Taras, 1976).

(ppm Ca X 2.5) + (ppm Mg X 4.1) = ppm hardness,

where the factors 2.5 and 4.1 are conversions for ppm Ca and Mg,
respectively, to ppm of CaCO,.

Table 19. Interpretation of the hardness scale for household water.
Rating Hardness (ppm)

Soft 0 to 17
Relatively Soft 18 to 50
Moderately Soft 51 to 120
Hard 121 to 170
Very Hard >170

2. Iron
High levels of Fe in home water can impart a metallic taste to water and can stain
clothes and plumbing. Staining can be caused by as little as 0.3 ppm Fe.

3. pH
Acid water is corrosive and, therefore, water should be on the alkaline side of the pH
range to prevent damage to metal parts of the water system.

4. Electrical Conductivity, Sodium, and Chlorides
Although all salts dissolved in water contribute to its electrical conductivity, high values
of Na and Cl are usually associated with salt water intrusion, which is a problem for many
wells in coastal areas. Water containing 0.4 to 0.6 dS/m tastes "salty" to most people.
There is no economical means at present for removing salts from water supplies.









5. Total Carbonates


The total carbonates test is reported but not used for households.

Irrigation Water

1. Electrical Conductivity, Na, and Cl
Table 20. Classification of irrigation water in terms of electrical conductivity (Adapted from Richards,
1954).


Class of Electrical
Irrigation Conductivity
Water (mmhos/cm)


Excellent <0.25
Good 0.25 to 0.75
Permissible 0.75 to 2.00 *
Doubtful 2.00 to 3.00
Unsuitable > 3.00

* Container nurseries using water with an electrical conductivity greater than 1.0 mmhos/cn should monitor
the electrical conductivity of the container media frequently to guard against salt build up.

2. pH
High pH irrigation water that contains carbonates and bicarbonates of Ca and Mg is
a problem with some deep wells. Irrigation with alkaline water may cause a gradual
increase in soil pH and lead to over-liming injury for soils already limed for optimum crop
production. For high-cash-value crops, it may be economically desirable to treat alkaline
water with an acid to reduce the harmful effects of excess carbonates. Notes in Soil Science
No. 18, "Neutralizing Excess Bicarbonates from Irrigation Water" (Kidder and Hanlon, 1985)
describes such water pretreatment, while Notes in Soil Science No. 25, "Quick-Test Method
for pH and Bicarbonates in Water" (Hanlon and DeVore, 1986) describes the use of a
portable field kit designed for use by county Extension faculty working with high pH water
problems.

3. Iron
Iron can be a problem for irrigation water under some conditions. In drip irrigation
systems as little as 0.3 ppm Fe may lead to clogging of the emitters. Some foliage plants
can be damaged by Fe stains if water high in Fe is used for overhead irrigation. The
quality of tobacco leaves has been damaged by deposits of Fe from irrigation water.








--- SECTION 6 ---


Interpretation of Container Media Test Results

Uses for the Container Media Test

The Container Media Test is designed for estimating the nutritional needs of plants
grown under intensive management typical of container-plant production. Specialized
interpretation of these results is necessary. Results are not meaningful for agronomic
situations or for home vegetable or flower gardens.

Container media differ greatly from agricultural soils in both physical and chemical
characteristics. The status of plant nutrients in soulless container media can be determined
best through the results of the Container Media Test.

Results of the Standard Soil Fertility Test should not be compared to results of the
Container-Media Test due to the different extraction procedures of each test. The
fundamental purpose of the Standard Soil Fertility Test is to act as a predictive manage-
ment tool for agricultural soils by estimating the portion of the Crop Nutrient Requirement
that must be supplied through fertilizer for the growing season. The Container Media
Test is designed as a diagnostic management tool for soilless media in which plants are
already growing.

Interpretation of Results

General interpretations for the Container Media Test are given in Tables 21 and 22.
However, it is advisable to observe plant growth and response to fertilizer management, as
well as to monitor nutrient status, through a regular program of media testing (refer to
IFAS Bulletin 231 and Circular 589 for more information). Such a program will help
producers to develop specific interpretations based upon media-test results for their
particular crops, media, and management situations.

When test results indicate that the container media is in the Low range, plants may
respond to added nutrients. The Acceptable range should be viewed as adequate for good
plant growth. Additions of nutrients to media testing Acceptable may or may not produce
additional plant growth. In general, plants may be ready for market 1 to 2 weeks earlier
if nutrients in the media are maintained in the Optimum range as compared to the
Acceptable range. No benefits are expected to added fertilizer when media nutrients test
in either the High or Very High ranges. In fact, excessive nutrient loss from the media
during irrigation, as well as nutrient disorders are possible, when nutrients are maintained
in either of these two ranges.

When making interpretations, one must consider that container-nutrient levels are
influenced by many factors including environmental factors, fertilizer solubility or release
characteristics, and water management. For example, a water-soluble nitrogen fertilizer
applied just prior to sampling may produce High nitrate-nitrogen media-test results that
may decrease or stabilize in subsequent samplings. Thus, repetitive, consistent sampling
is important to establish and maintain optimal nutrient levels in the container medium.
The Container Media test can be a valuable management tool to assist in fertilizer decisions,
especially when results can be interpreted in light of cultural management techniques used
by the producer.








--- SECTION 6 ---


Interpretation of Container Media Test Results

Uses for the Container Media Test

The Container Media Test is designed for estimating the nutritional needs of plants
grown under intensive management typical of container-plant production. Specialized
interpretation of these results is necessary. Results are not meaningful for agronomic
situations or for home vegetable or flower gardens.

Container media differ greatly from agricultural soils in both physical and chemical
characteristics. The status of plant nutrients in soulless container media can be determined
best through the results of the Container Media Test.

Results of the Standard Soil Fertility Test should not be compared to results of the
Container-Media Test due to the different extraction procedures of each test. The
fundamental purpose of the Standard Soil Fertility Test is to act as a predictive manage-
ment tool for agricultural soils by estimating the portion of the Crop Nutrient Requirement
that must be supplied through fertilizer for the growing season. The Container Media
Test is designed as a diagnostic management tool for soilless media in which plants are
already growing.

Interpretation of Results

General interpretations for the Container Media Test are given in Tables 21 and 22.
However, it is advisable to observe plant growth and response to fertilizer management, as
well as to monitor nutrient status, through a regular program of media testing (refer to
IFAS Bulletin 231 and Circular 589 for more information). Such a program will help
producers to develop specific interpretations based upon media-test results for their
particular crops, media, and management situations.

When test results indicate that the container media is in the Low range, plants may
respond to added nutrients. The Acceptable range should be viewed as adequate for good
plant growth. Additions of nutrients to media testing Acceptable may or may not produce
additional plant growth. In general, plants may be ready for market 1 to 2 weeks earlier
if nutrients in the media are maintained in the Optimum range as compared to the
Acceptable range. No benefits are expected to added fertilizer when media nutrients test
in either the High or Very High ranges. In fact, excessive nutrient loss from the media
during irrigation, as well as nutrient disorders are possible, when nutrients are maintained
in either of these two ranges.

When making interpretations, one must consider that container-nutrient levels are
influenced by many factors including environmental factors, fertilizer solubility or release
characteristics, and water management. For example, a water-soluble nitrogen fertilizer
applied just prior to sampling may produce High nitrate-nitrogen media-test results that
may decrease or stabilize in subsequent samplings. Thus, repetitive, consistent sampling
is important to establish and maintain optimal nutrient levels in the container medium.
The Container Media test can be a valuable management tool to assist in fertilizer decisions,
especially when results can be interpreted in light of cultural management techniques used
by the producer.








--- SECTION 6 ---


Interpretation of Container Media Test Results

Uses for the Container Media Test

The Container Media Test is designed for estimating the nutritional needs of plants
grown under intensive management typical of container-plant production. Specialized
interpretation of these results is necessary. Results are not meaningful for agronomic
situations or for home vegetable or flower gardens.

Container media differ greatly from agricultural soils in both physical and chemical
characteristics. The status of plant nutrients in soulless container media can be determined
best through the results of the Container Media Test.

Results of the Standard Soil Fertility Test should not be compared to results of the
Container-Media Test due to the different extraction procedures of each test. The
fundamental purpose of the Standard Soil Fertility Test is to act as a predictive manage-
ment tool for agricultural soils by estimating the portion of the Crop Nutrient Requirement
that must be supplied through fertilizer for the growing season. The Container Media
Test is designed as a diagnostic management tool for soilless media in which plants are
already growing.

Interpretation of Results

General interpretations for the Container Media Test are given in Tables 21 and 22.
However, it is advisable to observe plant growth and response to fertilizer management, as
well as to monitor nutrient status, through a regular program of media testing (refer to
IFAS Bulletin 231 and Circular 589 for more information). Such a program will help
producers to develop specific interpretations based upon media-test results for their
particular crops, media, and management situations.

When test results indicate that the container media is in the Low range, plants may
respond to added nutrients. The Acceptable range should be viewed as adequate for good
plant growth. Additions of nutrients to media testing Acceptable may or may not produce
additional plant growth. In general, plants may be ready for market 1 to 2 weeks earlier
if nutrients in the media are maintained in the Optimum range as compared to the
Acceptable range. No benefits are expected to added fertilizer when media nutrients test
in either the High or Very High ranges. In fact, excessive nutrient loss from the media
during irrigation, as well as nutrient disorders are possible, when nutrients are maintained
in either of these two ranges.

When making interpretations, one must consider that container-nutrient levels are
influenced by many factors including environmental factors, fertilizer solubility or release
characteristics, and water management. For example, a water-soluble nitrogen fertilizer
applied just prior to sampling may produce High nitrate-nitrogen media-test results that
may decrease or stabilize in subsequent samplings. Thus, repetitive, consistent sampling
is important to establish and maintain optimal nutrient levels in the container medium.
The Container Media test can be a valuable management tool to assist in fertilizer decisions,
especially when results can be interpreted in light of cultural management techniques used
by the producer.









Table 21. Interpretation of container media test for woody ornamentals (Adapted from Yeager and
Ingram, 1985).*

Rating Category
Analysis Very
Low Acceptable Optimum High High

pH <5.0 5.0-5.5 5.5-5.8 5.8-6.5 >6.5

Electrical
conductivity, dS/m <0.7 0.7-1.0 1.0-1.5 1.5-3.0 >3.0

Nitrate-N, mg/L <40 40-80 80-100 100-200 >200

Phosphorus, mg/L <3 3-8 8-12 12-18 >18

Potassium, mg/L <10 10-20 20-40 40-80 >80

Calcium, mg/L <10 10-20 20-40 40-100 >100

Magnesium, mg/L <10 10-15 15-20 20-60 >60


*Plants of the Ericaceae family (eg. azaleas) and salt-sensitive plants require only one half the levels of nutrients
shown in this table.




Table 22. Interpretation of container media test for bedding and pot plants (Warncke and Krawskoff,
1983).


Rating Category

Analysis Very
Low Acceptable Optimum High High

pH <5.3 5.3-5.6 5.6-5.8 5.8-6.5 >6.5

Electrical
conductivity, dS/m <0.8 0.8-2.0 2.0-3.5 3.5-5.0 >5.0

Nitrate-N, mg/L <40 40-100 100-200 200-300 >300

Phosphorus, mg/L <3 3-5 6-10 11-18 >18

Potassium, mg/L <60 60-150 150-250 250-350 >350

Calcium, mg/L <80 80-200 200400 >400

Magnesium, mg/L <30 30-70 70-140 >140








--- SECTION 7 ---

Literature Cited

Adams, F., and C.E. Evans. 1962. A rapid method for measuring lime requirement of
red-yellow podzolic soils. Soil Sci. Soc. Am. Proc. 26:355-357.

Adams, F., and D.L. Hartzog. 1980. The nature of yield responses of Florunner peanuts to
lime. Peanut Sci. 7:120-123.

Carter, D.L. 1981. Salinity and plant productivity. In: Chemical Rubber Co., Handbook Series
in Nutrition and Food. Chemical Rubber Co. Press, Boca Raton.

Dierolf, T.S., and G. Kidder. 1986. Laboratory evaluation of the Adams-Evans lime requirement
method for Florida's sandy soils. Soil Crop Sci. Soc. Fla. Proc. 45:29-33.

Hanlon, E.A., and J.M. DeVore. 1986. Quick-test method for pH and bicarbonates in water.
Notes in Soil Sci. No. 25. IFAS, Univ. of Fla, Gainesville.

Hanlon, E.A., and K.R. Munson. 1988. Forest soils of Florida: Useful groupings for forestry
purposes. Soil Sci. Factsheet SL-57. IFAS, Univ. of Fla, Gainesville.

Ingram, D.L., and R. W. Henley. 1983. Nursery laboratory development and operation. Fla.
Coop. Ext. Serv. Circ. No. 556. IFAS, Univ. of Fla., Gainesville.

Jarrell-Ash Division/Fisher Scientific Company. 1982. Jarrell-Ash ICAP-9000 Plasma
Spectrometer, Operator's Manual. Waltham, MA.

Kidder, G. and EA. Hanlon. 1985. Neutralizing excess bicarbonates from irrigation water.
Notes in Soil Science No. 18. IFAS, Univ. of Fla, Gainesville.

Kidder, G., N.B. Comerford, and A.V. Mollitor. 1987. Fertilization of slash pine plantations.
Circular No. 735. Fla. Coop. Extn. Ser., IFAS, Univ. of Fla., Gainesville.

Rand, M.C., A.E. Greenberg, and M.J. Taras (eds.). 1976. Standard methods for the
examination of water and wastewater. American Public Health Assoc., Washington,
D.C.

Richards, LA. (ed.). 1954. Diagnosis and improvement of saline and alkali soils. Agricultural
Handbook No. 60. U.S.D.A. Washington, D.C.

Southern Region Information and Exchange Group on Soil testing and Plant Analyses (SRIEG
18). 1983. Reference soil test methods for the Southern region of the United States.
So. Coop. Ser. Bull. 289. Univ. of Georgia, Athens, GA.

Warncke, D.D., and D.M. Krawskoff. 1983. Greenhouse growth media: Testing and nutrition
guidelines. Extn. Bull. E-1736. Mich. St. Univ., East Lansing, MI.

Yeager, T.H. 1986. Fertigation Management for the Wholesale Container Nursery. Fla. Coop.
Ext. Serv. Bull. 231. IFAS, Univ. of Fla., Gainesville.

Yeager, T.H., and D.L. Ingram. 1985. Container production of holly in Florida. Fla. Coop. Ext.
Serv. Circ. 589. IFAS, Univ. of Fla., Gainesville.

49




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