• TABLE OF CONTENTS
HIDE
 Front Cover
 Front Matter
 Foreword
 Table of Contents
 Introduction
 The fertilizer tag
 Sources of plant foods in...
 What happens to fertilizers in...
 Lime
 Appendix






Group Title: Bulletin - University of Florida Agricultural Experiment Station ; 506
Title: Know your fertilizers
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00026702/00001
 Material Information
Title: Know your fertilizers
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 24 p. : ill. ; 23 cm.
Language: English
Creator: Volk, G. M ( Gaylord Monroe ), 1908-
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1952
 Subjects
Subject: Fertilizers   ( lcsh )
Fertilizers -- Analysis   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
non-fiction   ( marcgt )
 Notes
Statement of Responsibility: G.M. Volk.
General Note: Cover title.
Funding: This collection includes items related to Florida’s environments, ecosystems, and species. It includes the subcollections of Florida Cooperative Fish and Wildlife Research Unit project documents, the Florida Sea Grant technical series, the Florida Geological Survey series, the Howard T. Odum Center for Wetland technical reports, and other entities devoted to the study and preservation of Florida's natural resources.
 Record Information
Bibliographic ID: UF00026702
Volume ID: VID00001
Source Institution: University of Florida
Holding Location: University of Florida
Rights Management: All rights reserved by the source institution and holding location.
Resource Identifier: aleph - 000925791
oclc - 18267391
notis - AEN6447

Table of Contents
    Front Cover
        Page 1
    Front Matter
        Page 2
        Page 3
    Foreword
        Page 4
    Table of Contents
        Page 4
    Introduction
        Page 5
    The fertilizer tag
        Page 6
        Page 7
        Page 8
        Page 9
        Page 10
        Page 11
    Sources of plant foods in fertilizers
        Page 12
        Page 13
        Page 14
        Page 15
    What happens to fertilizers in the soil
        Page 16
        Page 17
        Page 18
        Page 19
    Lime
        Page 20
    Appendix
        Page 21
        Materials other than standard mixed fertilizers frequently used for side-dressing or other special purposes
            Page 21
            Page 22
            Page 23
        Calculation of fertilizer formulas
            Page 24
Full Text




























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BOARD OF CONTROL

Frank M. Harris, Chairman, St. Petersburg
Hollis Rinehart, Miami
Eli H. Fink, Jacksonville
George J. White, Sr., Mount Dora
Mrs. Alfred I. duPont, Jacksonville
George W. English, Jr., Ft. Lauderdale
W. Glenn Miller, Monticello
W. F. Powers, Secretary, Tallahassee
EXECUTIVE STAFF
J. Hillis Miller, Ph.D., President3
J. Wayne Reitz, Ph.D., Provost for Agr.3
Willard M. Fifield, M.S., Director
J. R. Beckenbach, Ph.D., Asso. Director
L. O. Gratz, Ph.D., Assistant Director
Rogers L. Bartley, B.S., Admin. Mgr.8
Geo. R. Freeman, B.S., Farm Superintendent

MAIN STATION, GAINESVILLE

AGRICULTURAL ECONOMICS
H. G. Hamilton, Ph.D., Agr. Economists
R. E. L. Greene, Ph.D., Agr. Economist8
M. A. Brooker, Ph.D., Agr. Economists
Zach Savage, M.S.A., Associate
A. H. Spurlock, M.S.A., Associate
D. E. Alleger, M.S., Associate
D. L. Brooke, M.S.A., Associate
M. R. Godwin, Ph.D.,.Associates
H. W. Little, M.S., Assistant4
W. K. McPherson, M.S., Economist
Eric Thor, M.S., Asso. Agr. Economist
J. L. Tennant, Ph.D., Agr. Economist
Cecil N. Smith, M.A., Asso. Agr. Economist
Levi A. Powell, Sr., M.S.A., Assistant
Orlando, Florida (Cooperative USDA)
G. Norman Rose, B.S., Asso. Agri. Economist
J. C. Townsend, Jr., B.S.A., Agricultural
Statistician 2
J. B. Owens, B.S.A., Agr. Statistician 2
J. K. Lankford, B.S., Agr. Statistician
AGRICULTURAL ENGINEERING
Frazier Rogers, M.S.A., Agr. Engineer1 3
J. M. Johnson, B.S.A.E., Agr. Eng.3
J. M. Myers, B.S., Asso. Agr. Engineer
J. S. Norton, M.S., Asst. Agr. Eng.
AGRONOMY
Fred H. Hull, Ph.D., Agronomist 2
G. B. Killinger, Ph.D., Agronomist
H. C. Harris, Ph.D., Agronomist
R. W. Bledsoe, Ph.D., Agronomist
W. A. Carver, Ph.D., Associate
Darrel D. Morey, Ph.D., Associate 2
Fred A. Clark, M.S., Assistant2
Myron C. Grennell, B.S.A.E., Assistant4
E. S. Horner, Ph.D., Assistant
A. T. Wallace, Ph.D., Assistant 3
D. E. McCloud, Ph.D., Assistant
E. C. Nutter, Ph.D., Asst. Agronomist

ANIMAL HUSBANDRY AND NUTRITION
T. J. Cunha, Ph.D., An. Husb.13
G. K. Davis, Ph.D., Animal Nutritionist 3
S. John Folks, Jr., M.S.A., Asst. An. Hush.
Katherine Boney, B.S., Asst. Chem.
A. M. Pearson, Ph.D., Asso. An. Husb.3
John P. Feaster, Ph.D., Asst. An. Nutri.
H. D. Wallace, Ph.D., Asst. An. Husb. 5
M. KogerPh, Ph.D., An. Husandman 3
E. F. Johnston, M.S., Asst. An. Husbandman
J. F. Hentges, Jr., Ph.D., Asst. An. Hush.
DAIRY SCIENCE
E. L. Fouts, Ph.D., Dairy Tech.1 3
R. B. Becker, Ph.D., Dairy Husb.3
S. P. Marshall, Ph.D., Asso. Dairy Hush.3
W. A. Krienke, M.S., Asso. Dairy Tech."
P. T. Dix Arnold, M.S.A., Asst. Dairy Husb.'
Leon Mull, Ph.D., Asso. Dairy Tech.
H. H. Wilkowske, Ph.D., Asst. Dairy Tech.
James M. Wing, M.S., Asst. Dairy Husb.


EDITORIAL
J. Francis Cooper, M.S.A., Editor3
Clyde Beale, A.B.J., Associa e Editor
L. Odell Griffith, B.A.J., Asst. Editor3
J. N. Joiner, B.S.A., Assistant Editor 3
William G. Mitchell, A.B., Assistant Editor

ENTOMOLOGY
A. N. Tissot, Ph.D., Entomologist'
L. C. Kuitert, Ph.D., Associate
H. E. Bratley, M.S.A., Assistant
F. A. Robinson, M.S., Asst. Apiculturist
R. E. Waites, Ph.D., Asst. Entomologist

HOME ECONOMICS
Ouida D. Abbott, Ph.D., Home Econ.1
R. B. French, Ph.D., Biochemist

HORTICULTURE
G. H. Blackmon. M.S.A., Horticulturist
F. S. Jamison, Ph.D., Horticulturist "4
Albert P. Lorz, Ph.D., Horticulturist
R. K. Showalter, M.S., Asso. Hort.
R. A. Dennison, Ph.D., Asso. Hort.
R. H. Sharpe, M.S., Asso. Horticulturist
V. F. Nettles, Ph.D., Asso. Horticulturist
F. S. Lagasse, Ph.D., Asso. Hort.2
R. D. Dickey, M.S.A., Asso. Hort.
L. H. Halsey, M.S.A., Asst. Hort.
C. B. Hall, Ph.D., Asst. Horticulturist
Austin Griffiths, Jr., B.S., Asst. Hort.
S. E. McFadden, Jr., Ph.D., Asst. Hort.
C. H. VanMiddelem, Ph.D., Asst. Biochemist
Buford Thompson, M.S.A., Asst. Hort.
James Montelaro, Ph.D.. Asst. Horticulturist

LIBRARY
Ida Keeling Cresap, Librarian

PLANT PATHOLOGY
W. B. Tisdale, Ph.D., Plant Pathologist1'
Phares Decker, Ph.D., Plant Pathologist
Erdman West, M.S., Mycologist and Botanist
Robert W. Earhart, Ph.D., Plant Path.2
Howard N. Miller, Ph.D., Asso. Plant Path.
Lillian E. Arnold, M.S., Asst. Botanist
C. W. Anderson, Ph.D., Asst. Plant Path.

POULTRY HUSBANDRY
N. R. Mehrhof, M.Agr., Poultry Husb. 1
J. C. Driggers, Ph.D., Asso. Poultry Husb.

SOILS
F. B. Smith, Ph.D., Microbiologist 3
Gaylord M. Volk, Ph.D., Soils Chemist
J. R. Neller, Ph.D., Soils Chemist
Nathan Gammon, Jr., Ph.D., Soils Chemist
Ralph G. Leighty, B.S., Asst. Soil Surveyor'
G. D. Thornton, Ph.D., Asso. Microbiologist
Charles F. Eno, Ph.D., Asst. Soils Micro-
biologist 4
H. W. Winsor, B.S.A., Assistant Chemist
R. E. Caldwell, M.S.A., Asst. Chemist 3
V. W. Carlisle, B.S., Asst. Soil Surveyor
J. H. Walker, M.S.A., Asst. Soil Surveyor
S. N. Edson, M. S., Asst. Soil Surveyor
William K. Robertson, Ph.D., Asst. Chemist
0. E. Cruz, B.S.A., Asst. Soil Surveyor
W. G. Blue, Ph.D., Asst. Biochemist
J. G. A. Fiskel, Ph.D., Asst. Biochemist
H. F. Ross, B.S., Soils Microbiologist
L. C. Hammond, Ph.D., Asst. Soil Physicistl
H. L. Breland, Ph.D., Asst. Soils Chem.

VETERINARY SCIENCE
D. A. Sanders, D.V.M., Veterinarian
M. W. Emmel, D.V.M., Veterinarian
C. F. Simpson, D.V.M., Asso. Veterinarian
L. E. Swanson, D.V.M., Parasitologist
Glenn Van Ness, D.V.M., Asso. Poultry
Pathologist
W. R. Dennis, D.V.M.. Asst. Parasitologist
E. W. Swarthout, D.V.M., Poultry
Pathologist










BRANCH STATIONS

NORTH FLORIDA STATION, QUINCY
W. C. Rhoades, Jr., M.S., Entomologist in
Charge
R. R. Kincaid, Ph.D., Plant Pathologist
L. G. Thompson, Jr., Ph.D., Soils Chemist
W. H. Chapman, M.S., Asso. Agronomist
Frank S. Baker, Jr., B.S., Asst. An. Husb.
T. E. Webb, B.S.A., Asst. Agronomist
Frank E. Guthrie, Ph.D., Asst. Entomologist
Mobile Unit, Monticello
R. W. Wallace, B.S., Associate Agronomist
Mobile Unit, Marianna
R. W. Lipscomb, M.S., Associate Agronomist
Mobile Unit, Pensacola
R. L. Smith, M.S., Associate Agronomist
Mobile Unit. Chipley
J. B. White, B.S.A., Associate Agronomist

CITRUS STATION, LAKE ALFRED
A. F. Camp, Ph.D., Vice-Director in Charge
W. L. Thompson, B.S., Entomologist
R. F. Suit, Ph.D., Plant Pathologist
E. P. Ducharme, Ph.D., Asso. Plant Path.
C. R. Stearns, Jr., B.S.A., Asso. Chemist
J. W. Sites, Ph.D., Horticulturist
H. 0. Sterling, B.S., Ass:. Horticulturist
H. J. Reitz, Ph.D., Horticulturist
Francine Fisher, M.S., Asst. Plant Path.
I. W. Wander, Ph.D., Soils Chemist
J. W. Kesterson, M.S., Asso. Chemist
R. Hendrickson, B.S., Asst. Chemist
Ivan Stewart, Ph.D., Asst. Biochemist
D. S. Prosser, Jr., B.S., Asst. Horticulturist
R. W. Olsen, B.S., Biochemist
F. W. Wenzel, Jr., Ph.D., Chemist
Alvin H. Rouse, M.S., Asso. Chemist
H. W. Ford, Ph.D., Asst. Horticulturist
L. C. Knorr, Ph.D., Asso. Histologist
R. M. Pratt, Ph.D., Asso. Ent.-Pathologist
J. W. Davis, B.S.A., Asst. in Ent.-Path.
W. A. Simanton, Ph.D., Entomologist
E. J. Deszyck, Ph.D., Asso. Horticulturist
C. D. Leonard, Ph.D., Asso. Horticulturist
W. T. Long, M.S., Asst. Horticulturist
M. H. Muma, Ph.D., Asso. Entomologist
F. J. Reynolds, Ph.D., Asso. Hort.
W. F. Spencer, Ph.D., Asst. Chem.
I. H. Holtsberg, B.S.A., Asst. Ento.-Path.
K. G. Townsend, B.S.A., Asst. Ento.-Path.
J. B. Weeks, B.S., Asst. Entomologist
R. B. Johnson, M.S., Asst. Entomologist
W. F. Newhall, Ph.D., Asst. Biochem.
W. F. Grierson-Jackson, Ph.D., Asst. Chem.
Roger Patrick, Ph.D., Bacteriologist
Marion F. Oberbacher, Ph.D., Asst. Plant
Physiologist
Evert J. Elvin, B.S., Asst. Horticulturist

EVERGLADES STATION, BELLE GLADE
W. T. Forsee, Jr., Ph.D., Chemist Acting in
Charge
R. V. Allison, Ph.D., Fiber Technologist
Thomas Bregger, Pn.D., Physiologist
J. W. Randolph, M.S., Agricultural Engr.
R. W. Kidder, M.S., Asso. Animal Husb.
C. C. Seale, Associate Agronomist
N. C. Hayslip, B.S.A., Asso. Entomologist
E. A. Wolf, M.S., Asst. Horticulturist
W. H. Thames, M.S., Asst. Entomologist
W. N. Stoner, Ph.D., Asst. Plant Path.
W. G. Genung, B.S.A., Asst. Entomologist
Frank V. Stevenson, M.S., Asso. Plant Path.
Robert J. Allen, Ph.D., Asst. Agronomist
V. E. Green, Ph.D., Asst. Agronomist
J. F. Darby, Ph.D., Asst. Plant Path.
H. L. Chapman, Jr., M.S.A., Asst. An. Husb.
Thos. G. Bowery, Ph.D., Asst. Entomologist
V. L. Guzman, Ph.D., Asst. Hort.
M. R. Bedsole, M.S.A., Asst. Chem.
J. C. Stephens, B.S., Drainage Engineer2
A. E. Kretschmer, Jr., Ph.D., Asst. Soils
Chem.


SUB-TROPICAL STATION, HOMESTEAD
Geo. D. Ruehle, Ph.D., Vice-Dir. in Charge
D. 0. Wolfenbarger, Ph.D., Entomologist
Francis B. Lincoln, Ph.D., Horticulturist
Robert A. Conover, Ph.D., Plant Path.
John L. Malcolm, Ph.D., Asso. Soils Chemist
R. W. Harkness, Ph.D., Asst. Chemist
R. Bruce Ledin, Ph.D., Asst. Hor..
J. C. Noonan, M.S., Asst. Hort.
M. H. Gallatin, B.S., Soil Conservationist

WEST CENTRAL FLORIDA STATION,
BROOKSVILLE
William Jackson, B.S.A., Animal lluhand-
man in Charge 2

RANGE CATTLE STATION, ONA
W. G. Kirk, Ph.D., Vice-Director in Charge
E. M. Hodges, Ph.D., Agronomist
D. W. Jones, M.S., Asst. Soil Technologist

CENTRAL FLORIDA STATION, SANFORD
R. W. Ruprecht, Ph.D., Vice-Dir. in Charge
J. W. Wilson, Sc.D., Entomologist
P. J. Westgate, Ph.D., Asso. Hort.
Ben. F. Whitner, Jr., B.S.A., Asst. Hort.
Geo. Swank, Jr., Ph.D., Asst. Plant Path.

WEST FLORIDA STATION, JAY
C. E. Hutton, Ph.D., Vice-Director in Charge
H. W. Lundy, B.S.A., Associate Agronomist
W. R. Langford, Ph.D., Asst. Agronomist

SUWANNEE VALLEY STATION,
LIVE OAK
G. E. Ritchey, M.S., Agronomist in Charge

GULF COAST STATION, BRADENTON
E. L. Spencer, Ph.D., Soils Chemist in Charge
E. G. Kelsheimer, Ph.D., Entomologist
David G. A. Kelbert, Asso. Horticulturist
Robert O. Magie, Ph.D., Plant Pathologist
J. H. Walter, Ph.D., Plant Pathologist
Donald S. Burgis, M.S.A., Asst. Hort.
C. M. Geraldson, Ph.D., Asst. Horticulturist
Amegda Jack, M.S., Asst. Soils Chemist


FIELD LABORATORIES

Watermelon, Grape, Pasture-Lees! urg
C. C. Helms, Jr., B.S., Asst. Agronomist
L. H. Stover, Assistant in Horticulture

Strawberry-Plant City
A. N. Brooks, Ph.D., Plant Pathologist

Vegetables-Hastings
A. H. Eddins, Ph.D., Plant Path. in Charge
E. N. McCubbin, Ph.D., Horticulturist
T. M. Dobrovsky, Ph.D., Asst. Entomologist

Pecans-Monticello
A. Phillips, B.S., Asso. Entomologist
John R. Large, M.S., Asso. Plant Path.

Frost Forecasting-Lakeland
Warren O. Johnson, B.S., Meteorolo;:ist"

1Head of Department
In cooperation with U. S.
3Cooperative, other divisions, U. of F.
SOn leave









FOREWORD

By its very nature, agricultural research is rather technical,
and in its quest for the cause and control of problems confront-
ing the producer of food and fibre, it must give careful attention
to detail. Experiments normally are designed to handle specific
individual problems. Accordingly, when the results are published
they frequently are limited to specific projects, and sometimes
appear quite technical to readers who are not versed in the scien-
tific terminology of the subject matter specialist.
We have felt that there is need for certain bulletins which
could explain in general, non-technical terms some of the under-
lying principles and processes that are fundamental in the pro-
duction of crops. Technical terms in any industry cannot be
avoided for long when an individual has close contact with it.
Therefore, it is felt that a publication such as this, prepared by
an experienced research worker, will aid many folks in gaining
some basic information, and in an understanding of some of the
definitions of fertilizer terminology.
This bulletin was prepared at my personal request for the
purpose above outlined. I believe Dr. Volk has succeeded admir-
ably in meeting the requirements.
WILLARD M. FIFIELD
Director



CONTENTS
PAGE

THE FERTILIZER TAG ......... ...... .... --.... --- --------------..--- ..- --------..... 6
SOURCES OF PLANT FOODS IN FERTILIZERS .......... ...... -- ..-... .-- ...-- ... 12
WHAT HAPPENS TO FERTILIZERS IN THE SOIL ................ ................ 16
LIME ................ ...-------- ...---....-.... ... .... ...... ...... --..-.--.---.. ----.. 20
APPENDIX .......-...-....-........-..... -.- -.-- ---..... ...... 21
Materials other than standard mixed fertilizers frequently used for
side-dressing or other special purposes ...................... ........ 21

Calculation of fertilizer formulas ........ ....................... ............ 24









FOREWORD

By its very nature, agricultural research is rather technical,
and in its quest for the cause and control of problems confront-
ing the producer of food and fibre, it must give careful attention
to detail. Experiments normally are designed to handle specific
individual problems. Accordingly, when the results are published
they frequently are limited to specific projects, and sometimes
appear quite technical to readers who are not versed in the scien-
tific terminology of the subject matter specialist.
We have felt that there is need for certain bulletins which
could explain in general, non-technical terms some of the under-
lying principles and processes that are fundamental in the pro-
duction of crops. Technical terms in any industry cannot be
avoided for long when an individual has close contact with it.
Therefore, it is felt that a publication such as this, prepared by
an experienced research worker, will aid many folks in gaining
some basic information, and in an understanding of some of the
definitions of fertilizer terminology.
This bulletin was prepared at my personal request for the
purpose above outlined. I believe Dr. Volk has succeeded admir-
ably in meeting the requirements.
WILLARD M. FIFIELD
Director



CONTENTS
PAGE

THE FERTILIZER TAG ......... ...... .... --.... --- --------------..--- ..- --------..... 6
SOURCES OF PLANT FOODS IN FERTILIZERS .......... ...... -- ..-... .-- ...-- ... 12
WHAT HAPPENS TO FERTILIZERS IN THE SOIL ................ ................ 16
LIME ................ ...-------- ...---....-.... ... .... ...... ...... --..-.--.---.. ----.. 20
APPENDIX .......-...-....-........-..... -.- -.-- ---..... ...... 21
Materials other than standard mixed fertilizers frequently used for
side-dressing or other special purposes ...................... ........ 21

Calculation of fertilizer formulas ........ ....................... ............ 24










Know Your Fertilizers


By GAYLORD M. VOLK

Plants require at least 15 different chemical elements for their
growth processes. They require large quantities of carbon,
hydrogen and oxygen, which they obtain from air and water.
Nitrogen, potassium, phosphorus, calcium, magnesium and sulfur
also are used in considerable quantity by the plant. These ele-
ments may not be present in sufficient supply or in the proper
form. For example, air is four-fifths nitrogen gas, but only
the clovers and similar leguminous plants carrying nodule bac-
teria on their roots can use it. All other plants must have
nitrogen in combined forms such as is found in nitrate of soda,
sulfate of ammonia and certain other fertilizer materials.
In addition to the elements mentioned above, there is a group
of elements-iron, copper, manganese, zinc, boron and molyb-
denum-that are all essential for normal plant growth but
needed. only in very small quantities. The majority of soils
have enough of these elements, but certain of our sandy soils
are deficient in them. In some instances the nature of the soil
limits their availability to the plant.
Whenever any element is in short supply for plant growth,
it must be furnished by some kind of fertilization for economical
and profitable crop production.
The chemistry of fertilizers and their reaction with the soil
is very complex. The following discussion purposely omits the
use of chemical terms and symbols other than those appearing
on the fertilizer tag or as used in the Florida Commercial Fertil-
izer Law. However, this simplified presentation covers most
of the essential facts. It is based on a careful interpretation
by the author of the underlying chemistry of fertilizers and soils.
The chemical symbols used on the fertilizer tag to designate
various plant food constituents may be confusing to readers who
have had an introduction to chemistry. For example, nitrogen
is listed on the tag as the element, N; while phosphorus is given
as the oxide, P20,, and called phosphoric acid.
Florida Fertilizer Law designates the fertilizer constituents
simply as Primary Plant Foods or Secondary Plant Foods. This
terminology will be used in the discussion to follow. There is
some objection on the part of plant physiologists to the use of







Florida Agricultural Experiment Stations


the term Plant Food to designate fertilizer constituents, but
historical use in the fertilizer industry has set the precedent
for present usage.
Soil reaction (pH) plays a vital part in fertilizer efficiency.
It refers to the degree of acidity (sourness) or alkalinity (sweet-
ness) of a soil. To have a simple numerical measure, the pH
scale has been adopted. At pH 7.0 a soil is neither acid nor
alkaline, but neutral. As values decrease from pH 7.0 soil
acidity increases. As values rise above 7.0 soil alkalinity in-
creases.
Virgin Florida soils range from pH 3.8 (very acid) to pH 8.0
or slightly higher (alkaline). The strongly acid condition is
encountered in certain acid peats, mucks and palmetto flat-
woods. The alkaline condition is usually associated with marl
soils.
THE FERTILIZER TAG
There is a wealth of information on the Florida fertilizer tag.
This information, if understood by the grower, can often pre-

Fig. 1.-A Florida land pebble phosphate rock mine. (Photograph courtesy
American Agricultural Chemical Company.)







-W.

owl







Know Your Fertilizers


vent needless expenditure for materials containing unnecessary
elements, or crop losses resulting from the use of materials
lacking in some essential plant food.
A discussion of the fertilizer tag and what it means in terms
of practical use and economy of fertilizers will be made under
the following headings:
1. The fertilizer tag.
2. Sources of plant foods in fertilizers.
3. What happens to fertilizers in the soil
4. Lime.
Fertilizers differ in composition, depending upon how much
of each of the different plant foods they contain and the source
of these nutrients. A 100-pound bag of 3-8-8 1 analysis fertil-
izer contains three pounds of nitrogen, eight pounds of avail-
able phosphoric acid and eight pounds of water-soluble potash.
If the fertilizer contains six pounds of nitrogen, eight pounds of
phosphoric acid, and four pounds of potash, it has the analysis
6-8-4. The first figure always indicates the nitrogen, the second
the phosphoric acid and the third the potash. These are the
available primary plant foods. These figures are percentages
or units in fertilizer terminology. A 3-8-8 contains only one-
half as much nitrogen, but twice as much potash, as a 6-8-4.
Obviously these two fertilizers would not serve the same purpose.
Some fertilizers are very similar in analysis; from these ap-
proximately the same amounts of nitrogen, phosphoric acid and
potash may be applied to the crop by changing the amount of
fertilizer used per acre. When comparing one fertilizer analysis
with another, it usually is best to keep the nitrogen constant,
because plants usually are the most sensitive to deficiencies or
excesses of this plant food.
For example, if 15 100-pound bags of a 5-7-5 have been used
in the past, 15 times 5-7-5-or 75 pounds of nitrogen, 105
pounds of phosphoric acid and 75 pounds of potash-were used.
To determine how this compares with a 6-8-8, divide the 75
pounds of nitrogen by six (the pounds of nitrogen in a bag
of 6-8-8). This gives 121/2 bags of 6-8-8 as necessary to provide
75 pounds of nitrogen. At eight pounds each of phosphoric

1 In certain instances other numbers may be added to the analysis. For
example, a 5-6-6 might have more numbers added thus: 5-6-6-2-2. The
added numbers refer to secondary elements such as magnesium, copper,
zinc, etc. The use of this type of formula has not been generally accepted
by agriculturists to date.







8 Florida Agricultural Experiment Stations

acid and potash per bag of 6-8-8, the 121/ bags would supply
100 pounds of phosphoric acid and 100 pounds of potash. Twelve
and a half bags of 6-8-8, therefore, would supply five pounds
less phosphoric acid but 25 pounds more of potash and an equal
amount of nitrogen.2
The grower must decide whether the substitution of 121/
bags of 6-8-8 for 15 bags of 5-7-5 is permissible.3 If the change
is acceptable, the cost of 15 bags of 5-7-5 should be compared
to the cost of 121/ bags of 6-8-8 to determine if a saving is
made. Other factors involved will be described later, but in
general the fertilizer requiring the smallest number of bags or
pounds per acre will be most economical, even though the cost
per bag is higher.
The formula for the available primary plant foods of a 6-8-8
fertilizer would appear on the fertilizer tag in percentage (%)
as follows:

GUARANTEED ANALYSIS
Total Nitrogen, not less than ............................ ............... 6.00%
................................................................................... ............
-------- %
.....................%
--.-------- ......-- --.- ....----.-..---.... .-.- ......--%
.................................................................................... ----------./%
Available Phosphoric Acid, not less than ................................ 8.00%
.................................................................................... ............ %
Water-Soluble Potash, not less than ................. -............... 8.00%

In addition to the primary plant foods there are secondary
plant foods. These are reported in a similar manner at the
bottom of the tag if they are guaranteed present. The com-
monly recognized secondaries include calcium, magnesium, cop-
per, manganese, zinc, boron, iron, sulfur and molybdenum.4
There are certain required statements of forms and sources of
both primary and secondary plant foods which must appear
on the tag. An example of the above tag filled in as required
by law might read as follows:

2This method of visualizing the analysis probably will be the easiest to
remember and to use by the grower who buys limited amounts of fertilizer
and would like to have a method of comparing fertilizer analyses and costs.
Fertilizer formulation based on units and percentages is given in the
Appendix.
SArbitrarily increasing or decreasing phosphoric acid or potash applied
to a crop by more than one-fourth probably is not an economical practice
for crops where fertilizer requirements have been well established.
'These are reported as oxides, except sulfur, which is reported as the
element.







Know Your Fertilizers


GUARANTEED ANALYSIS
Line
Total N itrogen ....................................................... 6.00% 1
Nitrate Nitrogen ...... ................ 75% 2
Ammoniacal Nitrogen .............. .......-... 2.25% 3
Water-Soluble Organic Nitrogen ............... 2.10% 4
Water-Insoluble Nitrogen ......................... .90% 5
Available Phosphoric Acid ....-..... ............ ............. 8.00% 6
Insoluble Phosphoric Acid ...................... .20% 7
W ater-Soluble Potash .................................... ----8.00% 8
Total Available Primary Plant Food ............................ 22.00% 9
Chlorine, not more than ................................ 3.00% 10
Derived From: Castor Pomace, Tankage, Ammonium Nitrate, 11
Sulfate of Ammonia, Uramon, Ammoniated Superphosphate, 12
Sulfate of Potash, Muriate of Potash and Sulfate of 13
Potash Magnesia. 14
Derived From Secondary Plant Foods: 15
Water-Soluble Magnesia as MgO, not less than ...... 2.00% 16
Total Magnesia as MgO, not less than ........................ 2.00% 17
Copper Sulfate as CuO, not less than .......................... .50% 18
The line numbers do not appear on the tag but are inserted by
the writer for easy reference in the discussion to follow.
It will first be noted that the lines 1, 6 and 8, are the percent-
ages making the analysis as already discussed. Line 9 is the

Fig. 2.-Aerial view of rock phosphate washing plant. (Photograph
courtesy Davison Chemical Company.)







Florida Agricultural Experiment Stations


total of these three figures. If this total is relatively high it
will indicate a high analysis fertilizer. There is no set divid-
ing line, but fertilizers with a total of more than 24% would
usually be classed as high analysis fertilizers.
Lines 2, 3, 4 and 5 list the types of nitrogen which make up
the 6.00% total nitrogen. This is one of the most important
statements on the tag and will be discussed in the next section.
Line 7 gives the insoluble phosphoric acid. This form of
phosphoric acid is not included in the 8.00% available phos-
phoric acid of line 6, but is in addition to it.
Line 10 gives the maximum percentage of chlorine. Chlorine
ordinarily is not valued as a plant food in the fertilizer. It may
be injurious to certain crops, such as tobacco and potatoes, or
in plant bed fertilizers.
Lines 11 to 14 list the materials from which the primary plant
foods were obtained. This statement is of value to the grower
if only one source of a given plant food is listed or if a given
form of nitrogen is supplied only by one material. It is of little
value where a plant food or form of nitrogen comes from more
than one material, because the quantities of materials are not
given.
Lines 15 to 18 show the method of reporting secondary plant
foods. A knowledge of the source of these secondary plant
foods is important in order to know their availability to the plant.
The order and methods by which the sources of plant foods
are reported on the tag may vary to some extent with different
tags, but there should be no confusion if the above example
tag is thoroughly understood.
Conditioners and Fillers.-The amounts of various fertilizer
materials which are required to supply the primary and secon-
dary plant foods in a ton of a given formula usually do not total
2,000 pounds when mixed together. The remaining portion is
made up of conditioner or filler or both. A conditioner is a
material that helps prevent a fertilizer from becoming so moist
or so hard on standing that it will not drill properly. Condition-
ers may also supply some of the plant foods in the formula.
Filler is the term applied to a material added to fill out the
ton of weight. It often consists of dolomite, raw phosphate or
sand. It usually has certain conditioning value, but contains
no significant amount of available primary plant food.






TABLE 1.-APPROXIMATE ANALYSES OF SOME SOURCES OF PLANT FOOD.
(See Table 2 for Certain Other Nitrogen Materials)


Material


Ammonium sulfate ............
Ammo-Phos A ......................
Ammo-Phos B ...................
SA-N-L ................................
-Basic phosphate slag ..........
Borax ........................................
SCyanamid ................................
Calcium sulfate ... .........
\' al-N itro -------_--------..............
Coppeal-Nitro ...............................
Copperas ........ ...
Copper sulfate ...................
-'Castor pomace ....................
Cottonseed meal ....................
Emjo ......................... ............
Fish scrap ............................
Iron sulfate .----.............
Magnesium sulfate ...............
Manganese sulfate ..............
Muriate of potash .............
SNitrate of soda .....................
-Nitrate of soda-potash .......
Phosphate rock ..........:.....:....
Potassium nitrate ................
Sodium molybdate CP ..........
Sulfate of potash ..................
Sulfate of potash-magnesia..
Sul-Po-Mag .......................
Superphosphate, Regular ...
Superphosphate, Double ....
Tankage, Animal ..................
-Tobacco stems ......................
Zinc sulfate ........................


I N


20.6

20.5

5.4
7

8



16
15

13





8
2.2


[ Percentage Composition*


POS


K2O I CaO


MgO I


7



7



27

30







,18
18


S I NazO


Other


36 B,20


26 FeOa
30 CuO
-30 o


33 FeO,

30 MnO
44 Cl



59 MoO.
2 Cl
1 C1
1 C1



45 ZnO


* See text for meaning of symbols.


KO I CaO S I aO







Florida Agricultural Experiment Stations


SOURCES OF PLANT FOODS IN FERTILIZERS

The sources of the various available plant foods in fertilizers
differ to some extent in various parts of the country. The fol-
lowing discussion applies to Florida; high analysis fertilizers
requiring concentrated materials have not come into widespread
use here.
Some materials carry more than one plant food or form of
plant food. For example, ammoniated superphosphate may
carry nitrate nitrogen, ammoniacal nitrogen and phosphoric acid.
Nitrate Nitrogen.-This form of nitrogen comes mainly from
ammoniated superphosphate, ammonium nitrate, nitrate of soda
and nitrate of soda potash (Table 2). Ammoniated superphos-
phate is prepared by spraying ammoniating solutions on super-
phosphate. Ammoniating solutions used at present generally
contain ammonium nitrate and ammonia gas dissolved in water.
TABLE 2.-NITROGENOUS FERTILIZER MATERIALS.
Rate of
Fertilizer Material Percent Nitrogen
SNitrogen Availability


Nitrate of soda ............... .........................
Nitrate of soda-potash ..............................
Nitrate of potash ............................................
Calcium nitrate .......................................
Ammonium nitrate ........................ ........
Cal-Nitro ....................--..... ............
A -N -L ...................................... ................
Ammoniated superphosphate ........................
Ammonium sulfate ................... ...................
Urea ................ ... ..................... ......
N green ............................- ... .............. .......
U ram on .........................................................
Cyanam id ........................... ......... ............. ...
Cottonseed meal* ..........................................
Castor pomace* .........................................
Dried blood* ...................-................. ......
Hoof meal* ........................................................
Dry fish scraps* ............................... .............
Peruvian Guano* .......................................
Milorganite* ............................ .-.......... .
Nitroganic tankage* .......................................
Beetle scrap dust ....................... ...............
Animal tankage* .......................................
Hynite* ...................................... ..............
Processed tankage* ...............- ..................
Agrinite* ...................... .............................
Sm irow ...........................................................
Bone meal* ....................................................
Peanut hull meal* ........................................
Beetle molded scrap ........................................
Ground cocoa cake* ........................................
Garbage tankage* ......................................


* Natural organic.


16.2
15.0
13.2
15.5
33.0
20.5
20.5
(Variable)
20.5
46.6
44.0
42.0
20.6
6.7- 7.4
4.1- 6.6
9.0-14.0
10.7-15.6
6.5-10.0
5.0- 9.0
6.0- 6.4
5.0- 6.0
19.0
5.0-10.0
9.0-10.0
5.7-10.0
8.25
8.0-10.0
3.3- 4.1
1.2
19
3.06
2.5- 3.3


Very rapid
Very rapid
Very rapid
Very rapid
Very rapid
Very rapid
Very rapid
Rapid
Rapid
Rapid
Rapid
Rapid
Rapid
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Moderate
Slow
Slow
Slow
Slow
Slow
Slow
Slow
Very slow
Very slow
Very slow
Very slow
Very slow






Know Your Fertilizers


The nitrogen in ammonium nitrate is one-half ammoniacal
nitrogen and one-half nitrate nitrogen. All of the nitrogen in
nitrate of soda and nitrate of soda potash is in the nitrate form.
Calcium nitrate and nitrate of potash also carry all of their
nitrogen in the nitrate form, but are little used in Florida mixed
fertilizers at present. Crops can use the nitrate nitrogen from
different sources equally well.
Ammoniacal Nitrogen.-This form of nitrogen comes mainly
from ammoniated superphosphate, sulfate of ammonia and am-
monium nitrate. The ammoniacal nitrogen in ammoniated super-
phosphate is from the ammonia gas dissolved in the ammoniat-
ing solution and the ammonia portion of the ammonium nitrate.
All of the nitrogen in sulfate of ammonia is in the ammoniacal
form. Ammonium phosphate also carries all ammoniacal nitro-
gen and is often used in high analysis fertilizers. The ammonia-
cal nitrogen from different sources is equally usable by crops.
Water-Soluble Organic. Nitrogen.5-This form of nitrogen has

SThe name "organic nitrogen" refers to nitrogen of the type found in
organisms such as plants and animals. It includes certain of the nitro-
genous compounds now made synthetically but similar in certain respects
to natural organic nitrogen.
Fig. 3.-Receiving sodium nitrate from Chile at a Florida port. (Photo-
graph courtesy Wilson & Toomer Fertilizer Company.)









L 1 \ \^B .






Florida Agricultural Experiment Stations


been supplied mainly from urea and calcium cyanamide in
the past. The urea is made by chemical processes, but is identi-
cal with urea nitrogen found in the urine of animals. Calcium
cyanamide is a chemical combination of lime and nitrogen.
Both urea nitrogen and cyanamide nitrogen change to am-
moniacal nitrogen within a few days after application to the
soil when applied in the amounts usually found in mixed fertil-
izers. For this reason, the water-soluble organic nitrogen re-
ported on the fertilizer tag should be considered as the same as
ammoniacal nitrogen by the grower. The practice of including
it in a statement of total organic nitrogen is misleading to the
grower, who wants the high resistance to leaching characteristic
of the water-insoluble nitrogen of natural organic.
Water-Insoluble Nitrogen.-This form of nitrogen comes al-
most entirely from natural organic sources, such as the various
seed meals, tankages and sewage sludge products. A small amount
of water-insoluble nitrogen may come from synthetic materials.
The rate at which the insoluble nitrogen from different ma-
terials becomes available to the crop varies widely. Insoluble
nitrogen is a very high-cost form of nitrogen. It should not be
confused with the water-soluble organic form of nitrogen. In-
soluble nitrogen is also costly in another way, since, on the
average, only about one-third of this form of nitrogen now used
in fertilizers is available to the crop to which it is applied.
Available Phosphoric Acid.-This form of phosphorus comes
mainly from superphosphate, ammoniated superphosphate and
double superphosphate (treble superphosphate). These materials
are made by treating raw rock phosphate with acids or heat to
make the phosphorus more available to the plant. High an-
alysis fertilizers may contain considerable amounts of am-
monium phosphate. The available phosphoric acid from these
different materials is about equally usable by the crop.
*- Insoluble Phosphoric Acid.-This form of phosphorus must
not be confused with available phosphoric acid. It is largely
composed of rock phosphate or waste pond phosphate added
as filler, or the part of the rock phosphate that was not con-
verted to the available phosphoric acid form by acid or heat
treatments. This form of phosphoric acid is more slowly avail-

6 Urea has been supplied as a constituent of ammoniating liquors or
under the name Uramon in the past. It is understood that the use of the
latter name is being discontinued by the manufacturer.







Know Your Fertilizers


able to the plant; but over a long period of time does have
certain value and is therefore reported on the tag.7
Water-Soluble Potash.-Potash comes mainly from nitrate of
potash, sulfate of potash magnesia, nitrate of soda potash and
sulfate of potash. The water-soluble potash from different
sources is equally usable by the crop.
Chlorine.-This element comes almost entirely from muriate
of potash.8 Other forms of potash, such as sulfate of potash,
sulfate of potash magnesia and nitrate of soda potash, are used
if it is desirable to reduce the chlorine content of a fertilizer.
Secondary Plant Foods.-Considerable care must be used in
reading a fertilizer tag to determine the amounts of secondary
plant foods guaranteed. These secondaries may be from vari-
ous sources that differ widely in availability to the plant. The
water-soluble forms usually are the important sources in a
mixed fertilizer.9
Magnesium always is given as both water-soluble and total
under the name of magnesia, with the symbol MgO. Water-
soluble magnesium usually is derived from sulfate of potash
magnesia or magnesium sulfate. Other secondaries of import-
ance, with their symbols and commonly used water-soluble
sources, are as follows:
Tag
Plant Food Symbol Derived from
Copper CuO Copper Sulfate
Manganese MnO Manganese Sulfate
Zinc ZnO Zinc Sulfate
Boron B203 Borax, Borate
Iron Fe203 Iron Sulfate
Molybdenum MoOa Sodium Molybdate
Sulfur S Superphosphate, sulfate of potash
magnesia, ammonium sulfate o
Sodium Na2O Nitrate of soda o
Calcium CaO Calcium sulfate, superphosphate 0
Base Goods.-This term is frequently encountered in discus-
sion of fertilizer mixtures. It generally refers to a mixture of

SIt also indicates whether or not raw phosphate has been the form of
filler used and if the amount is significant. Multiplying by 100 will give
an estimate of the amount of waste pond phosphate filler that might have
been used per ton, or multiplying by 60 gives the equivalent of high grade
rock phosphate.
8 When potash is supplied from crude salts such as kainit, manure salts,
or sylvinite the amount of chlorine added with the source of potash usually
is considerably higher than when supplied only from muriate.
Some common sources of primary and secondary plant foods are listed
in Table 2.
0 These usually are not selected deliberately to supply the element
indicated.






Florida Agricultural Experiment Stations


several fertilizer materials, usually superphosphate, with ma-
terials containing ammonia or potash or both. This mixture,
after curing, is used as a base to which more materials may
be added to make different analyses.

WHAT HAPPENS TO FERTILIZERS IN THE SOIL
Nitrate Nitrogen.-Nitrate nitrogen dissolves readily in water
and moves freely in the soil with the movement of water. It
is not held by the soil particles. For this reason, heavy leaching
rains may remove the nitrate form of nitrogen. On the other
hand, this characteristic of nitrate nitrogen makes it a favored
side dressing, because the nitrogen moves more freely into the
soil and to the root zone than other forms of nitrogen. Nitrate
nitrogen is the form of nitrogen most universally preferred by
plants.
Ammoniacal Nitrogen and Soluble Organic Nitrogen.-Soluble
organic nitrogen converts to ammonia nitrogen in from three
to seven days under most soil conditions. For practical pur-
poses it may be classed with ammoniacal nitrogen.
Ammoniacal nitrogen dissolves readily in water. It differs
from nitrate nitrogen in that it is held by the soil particles and

Fig. 4.-Nitric acid plant for the production of ammonium nitrate.
(Photograph courtesy Lion Oil Company.)


\rslrt\L;iZ







Know Your Fertilizers


free movement through the soil is largely prevented. Move-
ment of ammoniacal nitrogen through a strongly acid soil is
more rapid than through a slightly acid soil. Therefore, proper
liming to reduce soil acidity (sourness) will help reduce the
leaching loss of ammoniacal nitrogen by heavy rains.
Most plants can use ammoniacal nitrogen to some extent, but
usually bacteria convert the ammoniacal nitrogen to nitrate
nitrogen in a period of one to four weeks. Plants then use the
nitrate nitrogen so formed. If the soil is strongly acid the
bacteria do not work well, and certain types of plants may suffer
from lack of the nitrate form of nitrogen. Soil that is saturated
with water, very dry or too cold also is slow to convert am-
moniacal nitrogen to nitrate nitrogen. For this reason nitrate
nitrogen is favored for rapid penetration of cold soils when side
dressing in late fall, winter and early spring.
Water-Insoluble Nitrogen.-Water-insoluble nitrogen cannot be
used directly by the plant but must be converted to ammoniacal
nitrogen by the soil organisms. This conversion proceeds grad-
ually and it is for this reason that insoluble nitrogen is more
slowly available to a crop and less subject to leaching loss by
heavy rains. It was a favored form of nitrogen in the past
when its cost was comparable to other forms of nitrogen.
The conversion of insoluble nitrogen proceeds more rapidly
in some materials than in others. In some, it is so slow as to
make them of little value as fertilizers. Many materials are
pretreated with heat or chemicals to increase this speed of con-
version to usable nitrogen in the soil. A list of nitrogenous
fertilizer materials is given in Table 1, with an estimated rate
of availability of their nitrogen.
Most natural organic nitrogen carriers have part of their
nitrogen in soluble form. This portion appears under the nitrate,
ammoniacal and water-soluble forms on the fertilizer tag. Re-
cent tests of the remaining water-insoluble nitrogen indicate
that on the average only about one-third of the insoluble nitrogen
added to fertilizers at present becomes available during the grow-
ing season in which it is applied. This means that the usable in-
soluble nitrogen in a fertilizer is very high in cost as compared
to other sources. It should be requested only if a real need
exists. The practice of side-dressing with cheaper nitrogen
while the crop is growing usually eliminates the need for high
amounts of insoluble nitrogen at time of planting.
Relative amounts of insoluble nitrogen from different sources







Florida Agricultural Experiment Stations


are not reported on the fertilizer tag. This makes it impossible
to determine which forms are being used in significant quan-
tities if more than one source is reported.
Phosphoric Acid.-All forms of phosphoric acid are strongly
held by the soil against loss by leaching, unless the soil is one
of the strongly acid white or gray sands of the palmetto flat-
woods. Moderate liming largely corrects this condition in the
flatwoods soils.
Available phosphoric acid is readily usable by the crop on all
soils. Soils that are red or yellow in the surface or subsoil tend
to hold phosphoric acid so strongly that on the second or third
year after application the availability of the residual phosphorus
may be much lower than for black or gray soils, making the
amount of phosphorus to be added to maintain fertility of the
red and yellow soils somewhat larger than for black or gray soils.
Insoluble phosphoric acid is more slowly available to the crop
than is available phosphoric acid. It is more rapidly available
on the moderately to slightly acid soils than on slightly acid
to high lime soils. For this reason available phosphoric acid

Fig. 5.-Mine site and refinery for potash salts near Carlsbad, New Mexico.
(Photograph courtesy American Potash Institute.)







Know Your Fertilizers


has been favored in the past for rapidly growing crops receiving
a drill application at time of planting; while the use of ground
rock phosphate has been confined largely to pastures.
Sulfur is known to be deficient in many soils in the Southeast.
The main source of this element in the past has been super-
phosphate. If ground rock phosphate is to be used continuously
on a given area, sooner or later sulfur will have to be supplied
to replace the sulfur removed by the crops.
Potash.-Potash is held in the soil much as is ammoniacal
nitrogen. In sandy soils it may be moved down out of the root
zone of shallow rooted crops to some extent, but apparently
much of it can be recovered by deep rooted crops.
Secondary Plant Foods.-Calcium, magnesium, copper, zinc,
manganese, iron and molybdenum are held in the soil much like
potash. Copper, zinc, manganese, iron and molybdenum are
held so strongly under certain conditions that they are relatively
unavailable to the crop.
Water-soluble sulfur and boron may move much like nitrate
nitrogen and be leached away. Almost all of the primary and
secondary plant foods may be tied up to some extent in the soil
microorganisms and organic matter (humus) and later be re-
leased to a crop when the organisms die or the organic matter
decomposes.
Fertilizer Injury.-High chlorine will reduce crop quality or
injure sensitive crops such as tobacco and potatoes in the field,
or cause injury in plant beds.
Too much usable nitrogen in the soil at one time may cause
leaf burn and injure the roots. The accumulation of soluble
salts from fertilizers or by irrigation with salty water will pre-
vent intake of water by the plant and reduce yield.
In general, the more sandy the soil and the drier the soil, the
more severe will be the injury from a given amount of excess
chlorine, nitrogen or total salts. Irrigating the crop to keep the
soil moisture high and to wash out some of the soluble salts
is the best method of correction in the field or in the plant bed.
Fertilizer Acidity.-Most fertilizers are acid-forming. This
acidity may be overcome by adding dolomite to the fertilizer
during mixing or by liming the soil. On the average, one ton
of fertilizerreires about 200 pounds of dolomite to neutralize
this acidity-
While it is preferable that the proper amount of dolomite be







Florida Agricultural Experiment Stations


added during mixing, many fertilizers are sold without this
being done. With certain high analysis fertilizers it is not
possible to add dolomite without reducing the amount of pri-
mary plant food in the analysis. For this reason, the acidity
of the soil should be determined every few years and lime added
if necessary.
LIME
Agricultural Limestone.-Proper liming of strongly acid soils
increases the efficiency of almost all plant foods added in the
fertilizer, as well as making many of those already held by the
soil more available to the crop. Much lime is lost by leaching,
especially where heavy fertilization is practiced.
Liming materials are used for the control of soil acidity. Agri-
cultural limestone, which is ground, crushed or pulverized lime-
stone rock, is used to the largest extent for this purpose. It
consists of calcium carbonate and magnesium carbonate and is
reported on the tag as percentages of these two compounds that
it carries. Eighty-four pounds of magnesium carbonate are
equal to 100 pounds of calcium carbonate in neutralizing soil
acidity.
Limestones containing appreciable amounts of magnesium
carbonate (usually between 36 and 46 percent) are called dolo-
mite. The magnesium is of value where this plant food is re-
quired in the soil. Dolomite is somewhat slower in correcting
soil acidity than are limestones containing little or no magnes-
ium.
The screen test as reported on the tag is very important in
determining the value of agricultural limestone-the finer the
material the more rapid is its reaction with the soil. Agricul-
tural limestone usually has a fineness such that about 85 per-
cent passes a 20-mesh 11 screen and 60 percent passes a 60-
mesh screen.
Hydrated Lime.-Hydrated lime is made by burning lime-
stone to quicklime and then slaking with water. It may consist
of calcium hydroxide or of mixtures of calcium hydroxide and
magnesium hydroxide and is so reported on the tag. The com-
bined neutralizing value of both materials is reported on the
tag as calcium carbonate equivalent. The magnesium hydroxide
is of special value where magnesium is needed in the soil.

"Number of wires per inch.







Know Your Fertilizers


* Hydrated lime is used to a considerable .extent for special
purposes. It reacts much faster with the soil than agricultural
limestone, therefore, more care is required in its use. Hydrated
lime should not be used at more than one-half the rate recom-
mended for agricultural lime.



APPENDIX

MATERIALS OTHER THAN STANDARD MIXED FERTILIZ-
ERS FREQUENTLY USED FOR SIDE-DRESSING
OR OTHER SPECIAL PURPOSES

Actomag (Selectively Calcined Dolomite).-This is a mixture
of finely divided magnesium oxide and calcium carbonate. A
typical analysis shows 27 percent magnesia. The magnesium
is intermediate in rate of availability between magnesium
sulfate and dolomite. It is used where magnesium especially
is needed by a crop.
Ammonium Nitrate.-This material is used as a top-dressing
or side-dressing where nitrogen only is needed. It contains
about 33 percent nitrogen and is used in much the same manner
as nitrate of soda, but is more concentrated and should be used
at a lower rate. One-half of the nitrogen is the same as that
in nitrate of soda and the other half is the same as that in sul-
fate of ammonia.
Anhydrous Ammonia.-This material is ammonia gas under
pressure and cannot be used except with special apparatus.
Usually it is injected into the soil behind a chisel-like implement.
It contains 83 percent ammoniacal nitrogen.
A-N-L.-This is ammonium nitrate to which dolomite has
been added to reduce the nitrogen content to 20.5 percent. It
is less concentrated than ammonium nitrate and therefore easier
to apply at light rates. (See Ammonium Nitrate.)
Basic S:ag (Thomas Slag).-Basic slag contains 8 to 25 per-
cent of phosphoric acid. In addition, 100 pounds of basic slag
are equal to about 70 pounds of limestone for the correction of
soil acidity. Basic phosphate slag is a name applied to basic
slag containing not less than 12 percent phosphoric acid of
which 80 percent is approximately equal to the available phos-
phoric acid of superphosphate.







Know Your Fertilizers


* Hydrated lime is used to a considerable .extent for special
purposes. It reacts much faster with the soil than agricultural
limestone, therefore, more care is required in its use. Hydrated
lime should not be used at more than one-half the rate recom-
mended for agricultural lime.



APPENDIX

MATERIALS OTHER THAN STANDARD MIXED FERTILIZ-
ERS FREQUENTLY USED FOR SIDE-DRESSING
OR OTHER SPECIAL PURPOSES

Actomag (Selectively Calcined Dolomite).-This is a mixture
of finely divided magnesium oxide and calcium carbonate. A
typical analysis shows 27 percent magnesia. The magnesium
is intermediate in rate of availability between magnesium
sulfate and dolomite. It is used where magnesium especially
is needed by a crop.
Ammonium Nitrate.-This material is used as a top-dressing
or side-dressing where nitrogen only is needed. It contains
about 33 percent nitrogen and is used in much the same manner
as nitrate of soda, but is more concentrated and should be used
at a lower rate. One-half of the nitrogen is the same as that
in nitrate of soda and the other half is the same as that in sul-
fate of ammonia.
Anhydrous Ammonia.-This material is ammonia gas under
pressure and cannot be used except with special apparatus.
Usually it is injected into the soil behind a chisel-like implement.
It contains 83 percent ammoniacal nitrogen.
A-N-L.-This is ammonium nitrate to which dolomite has
been added to reduce the nitrogen content to 20.5 percent. It
is less concentrated than ammonium nitrate and therefore easier
to apply at light rates. (See Ammonium Nitrate.)
Basic S:ag (Thomas Slag).-Basic slag contains 8 to 25 per-
cent of phosphoric acid. In addition, 100 pounds of basic slag
are equal to about 70 pounds of limestone for the correction of
soil acidity. Basic phosphate slag is a name applied to basic
slag containing not less than 12 percent phosphoric acid of
which 80 percent is approximately equal to the available phos-
phoric acid of superphosphate.






Florida Agricultural Experiment Stations


Calcium Sulfate (Landplaster, Gypsum).-This material is
used primarily as a source of sulfur when sulfur is needed but
not supplied in the usual manner by superphosphate or sulfates
of ammonia or potash. It is not a liming material for reducing
soil acidity.
Cal-Nitro.-This is ammonium nitrate to which dolomite has
been added to reduce the nitrogen content to 20.5 percent.
The material is less concentrated than ammonium nitrate
and therefore easier to apply at light rates. (See Ammonium
Nitrate.)
Colloidal Phosphate (Waste Pond Phosphate).-This is finely
divided raw mineral phosphate or phosphatic clay. If the phos-
phoric acid content is 20 percent or more it is approximately
equal to ground raw rock phosphate on an equivalent phosphoric
acid basis. For example, 300 pounds of 20 percent colloidal
phosphate would equal 200 pounds of 30 percent ground raw
rock phosphate. (See Rock Phosphate.)
Cottonseed Meal.-(See Natural Organics.)
Cyanamid (Calcium Cyanamide).-This material is 20.6 per-
cent nitrogen. The special precautions given by the manufac-
turer must be followed to prevent injury from the use of this
material. The nitrogen is synthetic, non-protein organic nitro-
gen and should not be confused with natural organic.
Gypsum.-(See Calcium Sulfate.)
Milorganite.-This is an activated sewage sludge of about 6.2
percent nitrogen and 3.5 percent phosphoric acid. (See Natural
Organics.)
Natural Organics.-Cottonseed meal and milorganite are two
materials quite commonly offered for direct use on the soil.
Their nitrogen is about 60 percent as available for an annual
crop as is the nitrogen in ammoniacal or nitrate form. Most
forms of natural organic nitrogen used at present have a much
lower rate of availability. The direct use of high cost natural
organic usually is not an economical practice except for land-
scaping, turf maintenance, plant beds or certain special crops.
Nitrate of Soda (Sodium nitrate); Nitrate of Soda-Potash;
Nitrate of Potash (Potassium nitrate.)-These materials all
carry only the nitrate form of nitrogen and are widely used for
side- or top-dressing. They carry from 13 to 16 percent nitrate







Know Your Fertilizers


nitrogen. In addition, nitrate of soda-potash carries 14 percent
of potash and nitrate of potash carries 46 percent of potash.
Nugreen.-This material carries 44 percent nitrogen in the
urea form and is intended primarily for use as a nutritional
spray. (See Urea and Solution Fertilization.)
Nutritional Sprays; Physiological Sprays.-(See Solution Fer-
tilization.)
Rock Phosphate.-This material consists of finely divided
phosphate rock and contains from 27 to 44 percent phosphoric
acid in insoluble form. It is moderately available to plants on
slightly to moderately acid soils and almost unavailable in high
lime soils. It is widely used as a soil builder. It is used to some
extent on pastures but is not suitable as a sole source of phos-
phorus for rapidly growing row crops.
Solution Fertilization.-Numerous fertilizer materials and
mixtures on the market are intended to be dissolved in water
and applied as sprays to the leaves while the crop is growing
or by dipping the roots or pouring in the holes in transplanting.
They are made from ordinary fertilizer materials which have
been purified and concentrated to eliminate insoluble residues.
These practices have a sound basis of fact but cannot be gen-
erally recommended because they are of economic value only
for very special conditions. The fertilizer materials prepared
for this use may be used also in the dry state like ordinary
fertilizers, but they usually are so concentrated that great care
is necessary in reducing the application to avoid injury to the
plants.
Starter Solutions.-(See Solution Fertilization.)
Sulfate of Ammonia (Ammonium Sulfate).-This material
contains about 20 percent nitrogen, all in ammoniacal form,
but no other primary plant food. Ammoniacal nitrogen does
not penetrate to the root zone as readily or give as quick a
response as does nitrate nitrogen when used as a side- or top-
dressing. On the other hand, ammoniacal nitrogen does not
leach out as readily when heavy rains occur. For this reason
it is used where quick response is not vital to the crop.
Urea.-Urea contains 46 percent water-soluble organic nitro-
gen that usually converts to ammoniacal nitrogen within two
to four days after application to the soil. It is called an organic
nitrogen but should not be confused with natural organic or







24 Florida Agricultural Experiment Stations

insoluble nitrogen. It is a very concentrated form of nitrogen
and difficult to use at a light rate of application, even when con-
ditioned, unless the analysis is reduced by adding a filler.

CALCULATION OF FERTILIZER FORMULAS
The fertilizer analysis shows the percentages of Nitrogen
(N), Available Phosphoric Acid (P205), and Potash (K20) in
that order. Thus a 6-8-7 contains 6% nitrogen, 8% phosphoric
acid and 7% potash; or 120 pounds of N, 160 pounds of P20,
and 140 pounds of K20 per ton. Analyses may then be com-
pared as to the amount of plant foods per ton of fertilizer.
One percent of plant food is also called one unit of plant food
and is equal to 20 pounds of that plant food per ton of fertilizer.
Assume that we wish to use sulfate of ammonia to supply
two of the six units of nitrogen in the 6-8-7. Table 1 shows
sulfate of ammonia to have 20.5% nitrogen. The calculations
are:
2,000 20.5(%) = 98 lbs. of ammonium sulfate to give one
unit of nitrogen.
2 x 98 lbs. = 196 lbs. of ammonium sulfate needed for 2 units
of nitrogen.
Or a grower may wish to know how much copper sulfate was
used in a mixture showing 0.5% CuO. The calculations are the
same. Table 1 shows copper sulfate as having 30% CuO.
2,000 30(%) = 66.7 lbs. per unit.
0.5(units) x 66.7 = 33 lbs. of copper sulfate per ton.
Fertilizer formulation tables usually show the number of
pounds of various fertilizer materials necessary to give one unit
of plant food per ton of mixed fertilizer.

SELECTED REFERENCES FOR FURTHER READING
ON FERTILIZATION
Commercial Fertilizers, Their Sources and Use. 4th Ed. G. H. Collings.
Blakiston Co., Philadelphia. 1947.
Soils and Fertilizers. 3rd Ed. Firman E. Bear. J. Wiley and Sons, Inc.,
New York. 1942.
Manual on Fertilizer Manufacture. Vincent Sauchelli. Davison Chemical
Corp., Baltimore. 1946.
Soil Reaction (pH). G. M. Volk and Nathan Gammon, Jr. Fla. Agr. Exp.
Sta. Circular S-39. 1951.
Soil Testing. F. B. Smith and Geo. D. Thornton. Fla. Agr. Exp. Sta.
Press Bull. 617. 1945.




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