• TABLE OF CONTENTS
HIDE
 Copyright
 Front Cover
 Table of Contents
 Introduction
 Plant nutrients and their functions...
 Effects of pasture management systems...
 Fertility maintenance programs...
 Summary
 List of other publications related...






Group Title: Bulletin - University of Florida. Agricultural Experiment Station - no. 515
Title: Maintaining fertility in mineral soils under permanent pasture
CITATION PAGE IMAGE ZOOMABLE PAGE TEXT
Full Citation
STANDARD VIEW MARC VIEW
Permanent Link: http://ufdc.ufl.edu/UF00027521/00001
 Material Information
Title: Maintaining fertility in mineral soils under permanent pasture
Series Title: Bulletin University of Florida. Agricultural Experiment Station
Physical Description: 31 p. : ill. ; 23 cm.
Language: English
Creator: Gammon, Nathan
Publisher: University of Florida Agricultural Experiment Station
Place of Publication: Gainesville Fla
Publication Date: 1953
 Subjects
Subject: Soil fertility -- Florida   ( lcsh )
Pastures -- Florida   ( lcsh )
Genre: government publication (state, provincial, terriorial, dependent)   ( marcgt )
bibliography   ( marcgt )
non-fiction   ( marcgt )
 Notes
Bibliography: Bibliography: p. 31.
Statement of Responsibility: M. Gammon, Jr. ... et al..
General Note: Cover title.
Funding: Bulletin (University of Florida. Agricultural Experiment Station) ;
 Record Information
Bibliographic ID: UF00027521
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: aleph - 000926029
oclc - 18270123
notis - AEN6688

Table of Contents
    Copyright
        Copyright
    Front Cover
        Page 1
        Page 2
        Page 3
    Table of Contents
        Page 4
    Introduction
        Page 5
    Plant nutrients and their functions in maintaining fertility
        Page 5
        Lime
            Page 5
            Page 6
            Page 7
        Nitrogen
            Page 8
            Page 9
            Page 10
        Phosphorus
            Page 11
            Page 12
            Page 13
        Potassium
            Page 14
        Minor elements
            Page 15
            Page 16
    Effects of pasture management systems on soil fertility and production
        Page 17
        Refertilization through feces and urine
            Page 17
            Page 18
            Page 19
        Cutting for hay or silage
            Page 20
    Fertility maintenance programs for soils under pasture
        Page 21
        Establishment
            Page 21
            Page 22
            Page 23
            Page 24
        Grass fertilization
            Page 25
            Page 26
        Legume grass fertilization
            Page 27
            Page 28
        Summer legumes
            Page 29
        Irrigated pastures
            Page 29
    Summary
        Page 30
    List of other publications related to pastures
        Page 31
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






Bulletin 515


March 1953


UNIVERSITY OF FLORIDA
AGRICULTURAL EXPERIMENT STATIONS
WILLARD M. FIFIELD, Director
GAINESVILLE, FLORIDA

Maintaining. Fertility in Mineral Soils
Under Permanent Pasture

N. GAMMON, JR., W. G. BLUE, J. R. NELLER, D. W. JONES,
H. W. LUNDY, G. E. RITCHEY

)~I


'* vAZr-.!TT,
I *"*- *i 1-4=-ii i









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., Presidents
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.*
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. Economist
M. A. Brooker, Ph.D., Agr. Economist 3
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
W. K. McPherson, M.S., Economist
Eric Thor, M.S., Asso. Agr. Economist
J. L. Tennant, Ph.IT., 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
J. K. Lankford, B.S., Agr. Statistician
AGRICULTURAL ENGINEERING
Frazier Rogers, M.S.A., Agr. Engineer 1
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., Assistant'
Myron G. Grennell, B.S.A.E., Assistant
E. S. Horner, Ph.D., Assistant
A. T. Wallace, Ph.D., Assistant 8
D. E. McCloud, Ph.D., Assistant 3
G. C. Nutter, Ph.D., Asst. Agronomist

ANIMAL HUSBANDRY AND NUTRITION
T. J. Cunha, Ph.D., An. Husb.1
G. K. Davis, Ph.D., Animal Nutritionist 3
S. John Folks, Jr., M.S.A., Asst. An. Husb. 3
A. M. Pearson, Ph.D., Asso. An. Husb.8
John P. Feaster, Ph.D., Asst. An. Nutri.
H. D. Wallace, Ph.D., Asst. An. Husb.8
M. Koger, Ph.D., An. Husbandman s
E. F. Johnston, M.S., Asst. An. Hush. 3
J. F. Hentges, Jr., Ph.D., Asst. An. Husb. 3
L. R. Arrington, Ph.D., Asst. Biochemist
DAIRY SCIENCE
E. L. Fouts, Ph.D., Dairy Tech. 3
R. B. Becker, Ph.D., Dairy Husb.8
S. P. Marshall, Ph.D., Asso. Dairy Husb.8
W. A. Krienke. M.S., Asso. Dairy Tech.'
P. T. Dix Arnold, M.S.A., Asst. Dairy Husb. 3
Leon Mull, Ph.D., Asso. Dairy Tech. ,
H. H. Wilkowske, Ph.D., Asst. Dairy Tech. 3
James M. Wing, Ph.D., Asst. Dairy Husb.


EDITORIAL
J. Francis Cooper, M.S.A., Editor"
Clyde Beale, A.B.J., Associate Editor
L. Odell Griffith, B.A.J., Asst. Editors
J. N. Joiner, B.S.A., Assistant Editor
William G. Mitchell, A.B.J., 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., Horticulturist1
F. S. Jamison, Ph.D., Horticulturist '
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., Horticulturist
R. D. DYickey, 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. K McFadden, Jr., Ph.D., Asst. Hort.
C. H. VanMiddelem, Ph.D., Asst. Biochemist
Buford D. Thompson, M.S.A., Asst. Hort.
James Montelaro, Ph.D., Asst. Horticulturist
M. W. Hoover, M.S.A., Asst. Hort.
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 8
Robert W. Earhart, Ph.D., Plant Path.S
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.1a
J. C. Driggers, Ph.D., Asso. Poultry Hush.
SOILS
F. B. Smith, Ph.D., Microbiologist s
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 2
G. D. Thornton, Ph.D., Asso. Microbiologists
Charles F. Eno, Ph.D., Asst. Soils Micro-
biologist
H. W. Winsor, B.S.A., Assistant Chemist
R. E. Caldwell, M.S.A., Asst. Chemist3'
V. W. Carlisle, B.S., Asst. Soil Surveyor
J. H. Walker, M.S.A., Asst. Soil Surveyor
S. N. Edson, M. S., Asst. Soil Surveyor3
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 3
L. C. Hammond, Ph.D., Asst. Soil Physicists
H. L. Breland, Ph.D., Asst. Soils Chem.
VETERINARY SCIENCE
D. A. Sanders, D.V.M.. Veterinarian 1 3
M. W. Emmel, IY.V.M., Veterinarian 3
C. F. Simpson, D.V.M., Asso. Veterinarian
L. E. Swanson, D.V.M., Parasitologist
Glenn Van Ness, D.V.M., Asso. Poultry
Pathologist 8
W. R. Dennis, D.V.M., Asst. Parasitologist
E. W. Swarthout, D.V.M., Asso. Poultry
Pathologist (Dade City)










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. Hush.
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. O. Sterling, B.S., Asst. 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. Ento.-Path.
R. B. Johnson, Ph.D., 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 in Charge
R. V. Allison, Ph.D., Fiber Technologist
Thomas Bregger, Ph.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. Hush.
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. Short.
J. C. Noonan, M.S., Asst. Hort.
M. H. Gallatin, B.S., Soil Conservationist

WEST CENTRAL FLORIDA STATION,
BROOKSVILLE
Marian W. Hazen, M.S., Animal Husband-
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 0. Magie, Ph.D., Plant Pathologist
J. M. 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-Leesburg
J. M. Crall, Ph.D., Associate Plant Path-
ologist Acting in Charge
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. M. Phillips, B.S., Asso. Entomologist'
John R. Large, M.S., Asso. Plant Path.

Frost Forecasting-Lakeland
Warren O. Johnson, B.S., Meterologist in
Chg.

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

















CONTENTS
Page

INTRODUCTION ...-...-.... -------- ---- -------- ..-..-- -------- 5

PLANT NUTRIENTS AND THEIR FUNCTIONS IN MAINTAINING FERTILITY
OF SOILS UNDER PASTURE .......----.........---......------------- 5

Lime ...............- ................ .. ... .................... .... 5

Nitrogen ........ --.... .--------..... --...---------------- ...------------ 8

Phosphorus and Sulfur ..........-..----.......-....---... .- ------.-- 11

Potassium ..---.........-.............--- ----------.....- ----------------- 14

Minor Elements ....------ ---............... ........... --- -- ---------- 15

EFFECTS OF PASTURE MANAGEMENT SYSTEMS ON SOIL FERTILITY AND
PRODUCTION ................------........--- -----.----------------.. 17

Refertilization Through Feces and Urine ................----------------------- 17

Cutting for Hay or Silage .......-............-........ .--- --------- 20

FERTILITY MAINTENANCE PROGRAMS FOR SOILS UNDER PASTURE ..........---... 21

Establishment --- ---................------ ---------- ... 21

Grass Fertilization ....----......... ---..... ---..----- ------- ----------- 25

Legume-Grass Fertilization ....---.............----.. ------------------ 27

Summer Legumes ....---...........- -----....-.-----------. 29

Irrigated Pastures -----.................----... --------- -------------- 29

SUMMARY ........--..------........------------ ------ 30

LIST OF OTHER PUBLICATIONS RELATED TO PASTURE .--..........------------.--------- 31








Maintaining Fertility in Mineral Soils

Under Permanent Pasture

N. GAMMON, JR., W. G. BLUE, J. R. NELLER, D. W. JONES,
H. W. LUNDY, G. E. RITCHEY

INTRODUCTION
The ultimate goal of a pasture program is animal feed for the
most economical production of meat or milk. Many of the pro-
duction problems on pastures result, either directly or indirectly,
from lack of understanding of the requirements for mainten-
ance of soil fertility.
The problem of fertility of soils under permanent pasture is
very complex. It cannot be wholly separated from the plants
growing in the pasture, the system of managing the pasture
for grazing, or the animals feeding on the pasture.
This discussion is based on observations of experimental plots
and representative pastures in widely scattered areas in the
state. It is presented primarily from the standpoint of fer-
tilizer and soil fertility factors, with illustrations on how these
factors influence pasture plants and ultimately the animals
feeding upon them. Conclusions drawn are based on data avail-
able; modifications may be necessary as more experience is
gained with the problem of maintaining soil fertility under
permanent pasture.
Many soils planted to improved pasture in Florida have very
low fertility. They require nitrogen, phosphorus and potash,
as well as lime and probably some of the minor elements, be-
fore abundant forage can be produced. In plant nutrition no
one nutrient element is of any more importance than another,
since all are essential for growth. If the fertility program omits
a nutrient element that is not supplied by the soil, the lack of
that element prevents maximum production. Discussion of
individual elements which go into the fertility program will
show the importance of each element.

PLANT NUTRIENTS AND THEIR FUNCTIONS IN MAIN-
TAINING FERTILITY OF SOILS UNDER PASTURE
Lime.-The first use of lime on pasture is to adjust the soil
reaction (acidity) to a suitable range for plant growth. Im-
proved pastures should be limed to a minimum soil pH of 5.5.








Maintaining Fertility in Mineral Soils

Under Permanent Pasture

N. GAMMON, JR., W. G. BLUE, J. R. NELLER, D. W. JONES,
H. W. LUNDY, G. E. RITCHEY

INTRODUCTION
The ultimate goal of a pasture program is animal feed for the
most economical production of meat or milk. Many of the pro-
duction problems on pastures result, either directly or indirectly,
from lack of understanding of the requirements for mainten-
ance of soil fertility.
The problem of fertility of soils under permanent pasture is
very complex. It cannot be wholly separated from the plants
growing in the pasture, the system of managing the pasture
for grazing, or the animals feeding on the pasture.
This discussion is based on observations of experimental plots
and representative pastures in widely scattered areas in the
state. It is presented primarily from the standpoint of fer-
tilizer and soil fertility factors, with illustrations on how these
factors influence pasture plants and ultimately the animals
feeding upon them. Conclusions drawn are based on data avail-
able; modifications may be necessary as more experience is
gained with the problem of maintaining soil fertility under
permanent pasture.
Many soils planted to improved pasture in Florida have very
low fertility. They require nitrogen, phosphorus and potash,
as well as lime and probably some of the minor elements, be-
fore abundant forage can be produced. In plant nutrition no
one nutrient element is of any more importance than another,
since all are essential for growth. If the fertility program omits
a nutrient element that is not supplied by the soil, the lack of
that element prevents maximum production. Discussion of
individual elements which go into the fertility program will
show the importance of each element.

PLANT NUTRIENTS AND THEIR FUNCTIONS IN MAIN-
TAINING FERTILITY OF SOILS UNDER PASTURE
Lime.-The first use of lime on pasture is to adjust the soil
reaction (acidity) to a suitable range for plant growth. Im-
proved pastures should be limed to a minimum soil pH of 5.5.








Maintaining Fertility in Mineral Soils

Under Permanent Pasture

N. GAMMON, JR., W. G. BLUE, J. R. NELLER, D. W. JONES,
H. W. LUNDY, G. E. RITCHEY

INTRODUCTION
The ultimate goal of a pasture program is animal feed for the
most economical production of meat or milk. Many of the pro-
duction problems on pastures result, either directly or indirectly,
from lack of understanding of the requirements for mainten-
ance of soil fertility.
The problem of fertility of soils under permanent pasture is
very complex. It cannot be wholly separated from the plants
growing in the pasture, the system of managing the pasture
for grazing, or the animals feeding on the pasture.
This discussion is based on observations of experimental plots
and representative pastures in widely scattered areas in the
state. It is presented primarily from the standpoint of fer-
tilizer and soil fertility factors, with illustrations on how these
factors influence pasture plants and ultimately the animals
feeding upon them. Conclusions drawn are based on data avail-
able; modifications may be necessary as more experience is
gained with the problem of maintaining soil fertility under
permanent pasture.
Many soils planted to improved pasture in Florida have very
low fertility. They require nitrogen, phosphorus and potash,
as well as lime and probably some of the minor elements, be-
fore abundant forage can be produced. In plant nutrition no
one nutrient element is of any more importance than another,
since all are essential for growth. If the fertility program omits
a nutrient element that is not supplied by the soil, the lack of
that element prevents maximum production. Discussion of
individual elements which go into the fertility program will
show the importance of each element.

PLANT NUTRIENTS AND THEIR FUNCTIONS IN MAIN-
TAINING FERTILITY OF SOILS UNDER PASTURE
Lime.-The first use of lime on pasture is to adjust the soil
reaction (acidity) to a suitable range for plant growth. Im-
proved pastures should be limed to a minimum soil pH of 5.5.







Florida Agricultural Experiment Stations


Soils that are more acid than this may produce herbage too
low in calcium content to supply the animals adequately. Acid
soils lose their potassium supply through leaching at more
rapid rates than do neutral or alkaline soils. Phosphorus is lost
from sandy flatwoods soils (6)1 and fixed as insoluble iron and
aluminum phosphates on the red and yellow soils under acid
conditions. Acid soils encourage the growth of undesirable soil
microorganisms. On the other hand, soils that are more nearly
neutral promote the growth of more useful soil microorganisms,
including some that can independently fix nitrogen from the
air.
In general, soils of all-grass pastures and pastures contain-
ing certain legumes that do not require a higher pH should be
maintained within the pH range of 5.5 to 6.0. Pastures con-
taining legumes with a high lime requirement should have soils
maintained in the pH range 6.0 to 6.5. Certain grasses, par-
ticularly the Bermudas, also grow more vigorously in the pH
range 6.0 to 6.5 than on more acid soils.
Lime should be applied to virgin soils, then mixed into the
surface three to four inches of the soil before applying fertilizer
and seeding or planting the pasture. Most virgin soils will re-
quire about one ton of high calcic limestone per acre to adjust
them to the pH range 5.5 to 6.0, and about two tons per acre to
adjust them to the pH range 6.0 to 6.5. However, to avoid
waste of materials and possible overliming injury, soil samples
should be taken and some estimate of lime requirement made
before applying the lime. Once the soil in a pasture has been
adjusted to the desired pH range it will require about one ton
of lime per acre every four to six years to maintain the soil
pH within the desired range.
Reservation is necessary in the evaluation of pH results from
soil samples taken after theapplication of lime (10). It is vir-
tually impossible to obtain a uniform distribution of lime over
the soil surface and even more difficult to obtain a thorough
mixing of lime and soil in the usual spreading and disking
operations. Consequently, soil areas are found with excessively
alkaline pH values where the lime has been heavily applied and
acid pH values where the lime was low or absent. Under these
conditions the soil pH value, as obtained from a fairly represen-
tative sample (9), will not necessarily represent the average pH
value of soil in the pasture. It may be as long as three years

1 Italic figures in parentheses refer to publications listed on last page.







Maintaining Fertility Under Permanent Pasture


before the slow diffusion of the lime in the soil would be such
that a pH value would be fully representative of the true soil
condition. This does not discredit the value of soil pH de-
terminations-it does caution those who may have made pH
determinations soon after liming of possible errors in interpre-
tation of the values obtained.
The liming materials commonly used on pasture soils are
high calcic limestone and dolomitic limestone. Basic slag also
is of considerable value as a liming material for pastures; this
will be discussed under phosphate sources. Other liming ma-
terials, such as quick or burned, and hydrated lime, have spe-
cial uses in agriculture but are more expensive and are not
usually recommended for use on pastures. High calcic lime-
stone-commonly sold as agricultural or ground limestone-
consists primarily of calcium carbonate but may contain a trace
of magnesium carbonate; while ground dolomitic limestone, or
dolomite, contains calcium carbonate and up to 46 percent mag-
nesium carbonate.
The calcium requirements of pasture plants are adequately
taken care of when the soils are kept within the recommended
pH zones. Responses to magnesium have not been observed
in pastures; however, magnesium deficiency has been recog-
nized in other plants growing on very sandy, well drained soils.
The general liming recommendation is to use either high calcic
or dolomitic limestone, whichever can be spread at lowest cost
in any given locality. A special exception might be made of
very sandy, well drained soils low in organic matter. Under
these special conditions use of dolomitic limestone would be
good insurance against future magnesium deficiency.
Liming materials are frequently sold under such terms as
superfine, pulverized, ground meal, and screenings to indicate
grades of fineness. The finer particles react with the soil and
change the pH in the shortest time; while the coarser particles
react more slowly and are more resistant to leaching. Lime-
stone that will not pass a 20-mesh sieve reacts so slowly that it
is of little value in adjusting soil pH. All material passing a
60-mesh sieve can be considered as potentially active liming
material. Grades meeting minimum standards of fineness as
agricultural limestone will be satisfactory for use on pastures.
There is no need to use the extra fine grades which are offered
at premium prices.
The use of excessive amounts of lime should be avoided for







Florida Agricultural Experiment Stations


three reasons. First, economical growth increases have not
been obtained at higher pH values. Second, rates of leaching
loss of limestone increase at these higher pH values-hence
the maintenance cost at this high level is increased because more
frequent applications of limestone are required. Third, there is
danger of overliming injury caused by the reduced solubility of
some of the minor elements.
The first two reasons require no further discussion, but the
problem of overliming injury requires more explanation. As
pH values increase, manganese, zinc, copper and some other
plant nutrients become less soluble, and plant roots may have
difficulty in extracting them from the soil. This is particularly
true of plants that normally produce their best growth under
acid conditions. Plants that thrive on near-neutral conditions
seem to be able to obtain these minor elements without much
difficulty. A few pastures in Florida that have been limed to
pH values as high as 8.2 are producing good herbage without
minor element deficiency symptoms. However, the minor ele-
ment supply in most Florida soils is low and excessive liming
presents an appreciable risk as well as being expensive.
Nitrogen.-Nitrogen is an essential part of both plant and
animal proteins. It represents about one-sixth of the weight
of these proteins. Since nitrogen is easily determined chemical-
ly in herbage, it is customary to estimate protein in herbage
by multiplying the percentage of nitrogen found in the herb-
age by the factor 6.25; thus 11/2 percent of nitrogen in herbage
is considered to be equivalent to 9.37 percent protein.
This conversion of nitrogen to protein is not technically cor-
rect, since only about one-half of the nitrogen in herbage is
present. as protein. However, its usage is acceptable because
ruminating animals are able to utilize these other forms of
nitrogen in the same manner as protein. The conversion of
plant nitrogen (protein) to animal proteins is one of the major
processes by which animals grow.
Nitrogen is the most expensive fertilizer element applied to
pastures. The cheapest method of obtaining nitrogen is through
the use 'of clovers, vetches, lespedezas, indigo and other legumes
in the pasture program. Nitrogen is taken from the air by
certain bacteria living on the roots of these leguminous plants,
and it then becomes available for the nutrition of the legume.
Later, upon death and decomposition of the legume, part of this
nitrogen becomes available for the grasses. Good management







Maintaining Fertility Under Permanent Pasture


of a pasture will include one or more of these legumes where
possible.
Despite the use of legumes, additional nitrogen is usually
necessary for maximum beef yields. For example, pastures of
winter clovers and grass are often low in nitrogen by mid-July.
An application of nitrogen then and in mid-August will keep
the grass growing vigorously, maintain a high protein content
and thereby increase beef gains. Pastures of grass alone will
require nitrogen fertilization at regular intervals throughout
the growing season to maintain grass quality and beef yields.
When nitrogen fertilizers are used on pastures the cheapest
forms of inorganic nitrogen available should be used. The fi-
brous roots of most pasture grasses are efficient in picking up
these forms of soluble nitrogen with a minimum of loss through
leaching. The ammoniated superphosphates, used primarily in
complete fertilizers, are one of the cheapest sources of nitrogen
for pastures. On a comparative basis fertilizer nitrogen in this
form can be purchased at about the same cost as the "hard
nitrogens" (nitrate of soda, ammonium nitrate, nitrate of pot-
ash, sulfate of ammonia or urea) with the phosphate carrier as
an additional plant food at no extra cost. Relatively new sources
of nitrogen-such as anhydrous ammonia and nitrogen liquors-
may prove to be satisfactory and cheap sources of nitrogen for
pastures. Time, rates and efficiency of application of nitrogen
in these forms as well as the need for extra potash when these
nitrogen materials are applied alone, have not been studied here.
If an adequate supply of other nutrients is available, one
pound of nitrogen per acre in the fertilizer should be sufficient
to produce a beef gain of five pounds or more. However, it is
not possible to apply 100 pounds per acre of nitrogen (equiva-
lent to 1,000 pounds of a 10-0-0 fertilizer) on a pasture in early
spring and feel assured that a yield of 500 pounds of beef per
acre will be obtained by proper grazing. Gains are made on
the first grass, but much of the nitrogen applied is returned to
the pasture in urine and manure spots. This results in the nitro-
gen becoming concentrated; it is then more readily lost through
leaching-or lost to the animals-since animals avoid eating
over such places. When a large amount of nitrogen is applied
at one time, much is lost before mid-summer, and beef gains
and grass quality decrease. By distributing the same amount
of nitrogen in two or three applications a month or six weeks
apart, the high protein content of the grass can be maintained,
and better beef gains may be obtained.







Florida Agricultural Experiment Stations


A good clover-grass pasture will produce in excess of 3,000
pounds per acre dry weight of high protein feed before June 1.
This herbage may contain over 100 pounds of nitrogen, and
represents most of the nitrogen supplied through the clover.
About this time of year the clover stops growing and no more
nitrogen is fixed from the air. Normal grazing, decomposition
of old clover roots, leaching and concentrating will have taken
their toll by mid-July. Additional fertilizer nitrogen should
then be applied or nitrogen will have to be fed as a protein
supplement to keep the cattle in good condition or to continue
gains.
The importance of maintaining a continuous supply of pro-
tein for the animals is well recognized. New legumes and sys-
tems of pasture management are being studied in an effort to
obtain this free nitrogen from the air on a year-round basis for
Florida pastures. Still, no completely successful system has yet
been devised for maintaining a year-round nitrogen supply on
Florida pasture through use of legumes. Dairymen or beef
producers should keep in mind the losses of nitrogen that result
from leaching or concentration. They should add additional
nitrogen fertilizer once beef gains or milk production drops, or
the pasture develops that light green appearance which indicates
a low nitrogen supply.
Total nitrogen in air-dry herbage in the pasture should exceed
1 to 2 percent (9 to 12 percent protein) for good production.
Well fertilized and properly inoculated leguminous plants may
contain as much as 5 percent total nitrogen (30 percent protein)
on a dry-weight basis. These plants can always be depended
upon to contain the minimum amount of nitrogen required for
good gains. Young, tender grass on a well fertilized pasture
usually is high in nitrogen, but as the grass grows the soil nitro-
gen becomes exhausted and that in the plant becomes more
dilute.
Grass containing less than 1/2 percent nitrogen (3 percent
protein) on a dry-weight basis is commonly found in pastures by
mid-summer. This grass may appear to be good feed, but cattle
have difficulty eating enough of it to get the protein necessary
to make gains. Nitrogen fertilization at this time will quickly
increase the protein concentration in the grass and increase
cattle gains. Feeding the cattle a concentrated protein supple-
ment while grazing on the low-nitrogen grass has the same
effect but may be more expensive.






Maintaining Fertility Under Permanent Pasture


In summary, Florida soils are low in nitrogen. Usually the
cheapest nitrogen for pastures is obtained from the air through
bacteria living on the roots of leguminous plants. Most pas-
tures will require some supplemental nitrogen if the protein
percentage in the grass is to be kept high enough for good cat-
tle gains (Fig. 1). Nitrogen is quickly leached from the soil
by heavy rains unless it is picked up by the roots of the pasture
plants. Losses of nitrogen are increased by high concentrations
in localized manure and urine spots which are more readily
leached and which are usually not grazed by the cattle.
Phosphorus.-Most Florida soils are low in available and total
phosphorus. Exceptions are noted in the Arrendondo and re-
lated soil types. These types have developed from a parent
material that consisted primarily of phosphatic limestone. The
red and yellow soils of North and West Florida have a high phos-
phate fixing power. Fertilizer phosphates applied to these soils
combine chemically with iron and aluminum in such a way that
the phosphate is not available to the plant roots in sufficient
quantity for maximum growth. Usually these soils show a
marked response to phosphate applications the first two or three
years after they have been put into improved pasture. After
the first few years the fixing capacity of the iron and aluminum

Fig. 1.-Dairy cows on a Pangola grass pasture fertilized at a high rate
with nitrogen.







Florida Agricultural Experiment Stations


is largely satisfied, and more of the applied phosphate is avail-
able to the plants. Applying sufficient lime to bring these soils
to a pH 6.0 or higher is also helpful, because it reduces the
amount of iron and aluminum available for fixing phosphate.
Thus more phosphate remains available for the plant.
The sandy soils of the flatwoods areas, gray to black in ap-
pearance, contain little surplus iron or aluminum. Phosphates
applied to these soils remain available to the plant unless the
soil acidity factor is neglected. If these soils remain at their
native pH-usually between pH 4.0 and pH 5.0-there is a
downward movement of phosphorus; most of the normal appli-
cation of superphosphate would be gone within a year. How-
ever, on properly limed soils (pH 5.5 or higher) at least three-
fourths of the phosphate from an annual application of 500
pounds per acre of superphosphate will remain in the surface
three inches of soil. Most of this phosphate is present as a
calcium phosphate that is moderately available to plants. It is
not surprising that further applications of phosphate cause
relatively little growth response on these soils.
Since a relatively small amount of the applied fertilizer phos-
phate is required by the plants, it seems reasonable that after
the first few years phosphate fertilization could be drastically
reduced. However, there are two factors which tend to en-
courage larger applications of phosphate. First, most phosphate
is applied as superphosphate, which contains sulfur. Some fer-
tilizer sulfur is necessary on almost all soils of Florida if a good
growth of clover is to be obtained.
The second reason for use of superphosphate is one previ-
ously mentioned-that it is the nitrogen carrier of the low-
cost ammoniating solutions used in many mixed fertilizer
formulas. It can be seen that, after the initial phosphate re-
quirements are met on soils under pasture conditions, more
phosphate than is actually required for plant growth may be
applied as superphosphate, since it is a good source of sulfur
and may serve as a carrier for low-cost nitrogen. This use of
surplus phosphate to obtain sulfur or low-cost nitrogen is not
a recommended practice. It is discussed here because many
people fail to recognize the secondary plant food and mixed
fertilizer formulation values of superphosphate.
Sulfur is closely linked to phosphorus because it is a part of
superphosphate, and its true importance is often overlooked
(7). Growth responses observed in the field when superphos-







Maintaining Fertility Under Permanent Pasture


phate is used are usually attributed to the phosphate.
However, these responses, especially on soils that have had
considerable previous fertilization, are often due to the sulfur in
the superphosphate.
Although fertilizer requirements for sulfur have not been
determined, it is known that the sulfur in superphosphate ap-
plied at 500 pounds per acre is adequate. It is probable that
a smaller amount would be sufficient, since sulfur is soluble
and the total requirement for the plant is small. Sulfur (as
sulfate) is readily leached from the soil, apparently moving
downward at a slightly slower rate than nitrate, chloride or
calcium. Plants and soil microorganisms convert sulfates into
relatively insoluble organic forms. This helps to prevent its
leaching, and residual effects of sulfur applications are some-
times observed in crops a year after application.
Other phosphate materials that can be used on pastures in-
clude rock phosphate, colloidal phosphate, calcined phosphate
and basic slag. Rock and colloidal phosphate have proved to be
good sources of phosphorus on the flatwoods soils, but some
source of a sulfur supplement must be provided if good clover
growth is desired. Gypsum at 175 pounds per acre or flowers of
sulfur at 40 pounds per acre are known to be adequate as supple-
ments to non-sulfur carrying phosphate sources. On the red and
yellow soils of Northwest Florida rock and colloidal phosphates
have not produced as good growth as other phosphate sources.
Calcined phosphate (heat-treated or defluorinated rock phos-
phate) is a satisfactory phosphate source provided a source of
sulfur is added.
Basic slag has proved to be a good source of phosphate. Since
it contains a small amount of sulfur, responses to additional
quantities of sulfur are less pronounced than with rock or
colloidal phosphate. Basic slag also contains significant quan-
tities of manganese. It would be particularly useful on soils
where this element is deficient. A secondary function of basic
slag is its soil neutralizing value. This is equivalent to 70
percent of the neutralizing value of high calcic limestone. Thus
the application of 1,000 pounds of basic slag, in addition to sup-
plying phosphate, supplies the equivalent of 700 pounds of high
calcic limestone.
These phosphate sources are most useful in satisfying the
initial phosphate requirement of a soil being developed for
pasture. For general pasture fertilization superphosphate is






Florida Agricultural Experiment Stations


probably most useful, since it can serve as a low-cost nitrogen
carrier for grass pastures and also supplies the sulfur necessary
for clovers.
Potassium.-Florida soils are low in available potassium and
the potassium reserve in insoluble soil minerals is also low.
Consequently, potassium deficiencies are frequently observed
in inadequately fertilized pastures. Potassium does not com-
bine with organic substances to form less soluble reserves, as
do nitrogen, sulfur and phosphorus. Hence, very shortly after
the death of a plant or soil microorganism, potassium is re-
leased. It is then subject to loss through leaching rains.
Little potassium is retained by the animal; most of that in
the herbage is promptly returned to the pasture in urine and
manure. This means that sufficient potassium to produce herb-
age over a wide soil area is concentrated and returned to a
small soil area. It is then leached more rapidly than would
be the case if it were uniformly spread, since the soil properties
that reduce potassium leaching are not present in sufficient
quantity to stop leaching of the concentrated amounts. The
few plants that obtain nutrients from these concentrated areas
are largely avoided by cattle. On the sandier soils in Florida,
a large amount of the potassium taken up by pasture plants
may be lost after only one cycle through the animal.
Since Florida soils have a low initial supply of potassium, and
the percentage of potassium recovered and re-used after one
grazing is probably low, the amount of potassium supplied in
the fertilizer has a direct bearing on the total amount of feed
that can be produced by the pasture. For example, the grazed
portion of normal white clover plants contains about 2 percent
potassium on a dry-weight basis. A yield equivalent to one ton
of dry weight per acre is not unusual. Thus, the grazed ma-
terial alone, without considering the remainder of the plant,
contains potassium equivalent to that found in 500 pounds of
0-14-10 fertilizer.
Grazing would in effect remove most of an average applica-
tion of fertilizer potassium from the pasture and concentrate it
in a very small portion of the total area. Further growth of
clover and grass over most of the area in the pasture for the
balance of the year would depend upon the inadequate potassium
reserve in the soil, unless additional fertilizer potassium is ap-
plied. When clovers have reduced available soil potassium to
the range of 50 to 70 pounds per acre, potassium deficiency







Maintaining Fertility Under Permanent Pasture


symptoms begin to appear on the leaves. Deficient clover plants
may contain as little as 0.6 percent potassium on a dry weight
basis.
Grasses will make good growth on a much smaller supply of
potassium. Normal grass herbage, on a dry-weight basis, con-
tains about 1 percent potassium. Serious deficiency symptoms
do not appear until the potassium supply drops to less than 0.4
percent. It is of interest to note that grasses seem to be capa-
ble of lowering the potassium supply in the soil to less than 20
pounds per acre.
Grasses and clovers take. up a surplus of potassium if it is
available in the soil. This point should be carefully considered
in a pasture management program; since early grazing of a
pasture containing small plants on a "luxury diet" of potassium
leads to early removal, concentration and loss of potassium and
a consequent loss of potential dry weight production in the
pasture.
Sodium will replace as much as 50 percent of the potassium
requirements of Pangola grass without affecting growth. Since
pasture soils are often very low in available potassium by mid-
summer, the value of the sodium in nitrate of soda top-dressings
on Pangola sods during this period cannot be ignored. Equal
or better growth response could be expected from nitrate of
potash or from equivalent amounts of other nitrogen sources if
accompanied by muriate of potash or a mixture of equal parts
of sodium chloride and muriate of potash. Preliminary observa-
tions indicate that no appreciable quantity of sodium can be
utilized as a replacement of the potassium requirements of the
clovers or the other major pasture grasses used in Florida.
Minor Elements.-Minor elements closely associated with soil
fertility and production of herbage on Florida pastures include
zinc, copper, manganese and boron. Growth responses to ap-
plications of these elements on pasture have been noted in
Florida and in other coastal plain states in the Southeast. Ef-
fects of minor elements are not always directly apparent as in-
creases in growth. Boron, for example, may increase the seed
production of clovers without any significant increase in herb-
age.
An adequate supply of these elements may increase the dura-
bility of clover, so that old plants will withstand the scalding
heat of the summer months and start a flush of fall growth.
This growth will then be ready for grazing months before new







Florida Agricultural Experiment Stations


seedling plants would have made equivalent development.
Strong, healthy plants well supplied with minor elements may
also be able to withstand the effects of drought, disease or cold
which would destroy a weaker plant.
Conditions that favor or demonstrate a minor element re-
sponse do not always duplicate themselves year after year. A
response one year may be masked by another set of conditions
the second year. However, evidence is being accumulated which
shows that minor element responses on pastures are widespread
in Florida. The use of minor elements in fertilizing many pas-
ture soils is cheap insurance and may make or save a crop.
Plant nutrient requirements for these minor elements are not
high. With the possible exception of boron, these elements do
not leach readily from the soil. On experimental plots a single
application of copper, zinc and manganese is still producing a
growth response on clover six years after application. The
generally low requirement for the minor elements, the rather
high degree to which most of them are retained in the soil, and
the possibility that some of them can be built up to toxic ex-
cesses all lead to the conclusion that minor element fertilizers
should be used sparingly.
A suggested general insurance program of minor element
fertilization includes 15 pounds per acre of each of the follow-
ing: copper sulfate (CuSO4.5H20), zinc sulfate (ZnSO4.HO2),
and manganous sulfate (MnSO4.4H20). These materials should
not be applied more frequently than once in five years under
ordinary pasture conditions, unless some specific deficiency is
known to exist that requires a heavier rate of application for
correction.
Boron deficiency has been recognized on some Florida pas-
tures, especially where clovers are being grown. Since boron
leaches readily from sandy soils an annual application of 10
pounds per acre of borax (Na2B407.10H20) may be necessary on
the lighter soils which are known to be deficient in this element.
On pastures that have not shown response to boron, no borax
need be applied, except possibly once in five years as an insur-
ance item. The mineral supplement which is commonly used
to supply cattle with additional minerals usually contains minor
elements. These eventually reach the soil and contribute to the
supply available to pasture plants.
Minor element deficiencies do not always follow soil types or
textures. However, some generalizations are possible if ex-







Maintaining Fertility Under Permanent Pasture


ceptions are remembered. Copper responses are usually en-
countered on the acid flatwood soils of the Leon and Immokalee
group in central and southern Florida. Peats, peaty mucks
and muck soils almost universally show plant or animal re-
sponses to copper application. Zinc responses occur most fre-
quently on the red and yellow soils of northern and western
Florida. Relatively few responses to zinc have been observed
on pastures in central and southern Florida.
Responses to manganese on pastures have been relatively
few and may be associated with overliming. However, the total
or reserve manganese supply in many of the acid flatwoods
soils is low. Boron responses have been limited to pastures
growing legumes, and they are frequently associated with the
lighter, coarse-textured sands. Boron responses are observed
on heavier-textured soils, but areas reporting them are so
scattered that it is difficult to predict boron-deficient soils with-
out actual field experiments.

EFFECTS OF PASTURE MANAGEMENT SYSTEMS ON
SOIL FERTILITY AND PRODUCTION
Refertilization Through Feces and Urine.2-Much of the fer-
tilizer applied to pastures and taken up by the herbage is
eventually returned to the pasture as feces and urine. Of the
fertilizer elements, nitrogen is removed in largest quantities
from the pasture as beef or milk protein. The amounts of
phosphorus, calcium and potassium removed by the animals are
small compared to nitrogen. However, all elements returned to
the soil are concentrated in relatively small areas as urine and
feces spots. This has the effect of depleting most of the pas-
ture area of nutrients.
If the pasture is of low fertility and one animal must graze
several acres to obtain sufficient herbage for normal nutrition,
the area of concentration is relatively much smaller than when
several animals can find sufficient food on a single acre. In
these zones of concentration, leaching losses, particularly of
nitrogen and potassium, are greatly accelerated. This, plus
the natural avoidance of these areas by the animals, leads to
general reduction in plant nutrients and soil fertility.
Tables 1 through 4' illustrate some of the major fertilizer
2 The term manure as used includes feces and urine.
3 Selection of data from "Farm Manure" by R. M. Salter and C. J. Schol-
lenberger, Ohio Agr. Exp. Sta. Bul. 605. September 1939.







Maintaining Fertility Under Permanent Pasture


ceptions are remembered. Copper responses are usually en-
countered on the acid flatwood soils of the Leon and Immokalee
group in central and southern Florida. Peats, peaty mucks
and muck soils almost universally show plant or animal re-
sponses to copper application. Zinc responses occur most fre-
quently on the red and yellow soils of northern and western
Florida. Relatively few responses to zinc have been observed
on pastures in central and southern Florida.
Responses to manganese on pastures have been relatively
few and may be associated with overliming. However, the total
or reserve manganese supply in many of the acid flatwoods
soils is low. Boron responses have been limited to pastures
growing legumes, and they are frequently associated with the
lighter, coarse-textured sands. Boron responses are observed
on heavier-textured soils, but areas reporting them are so
scattered that it is difficult to predict boron-deficient soils with-
out actual field experiments.

EFFECTS OF PASTURE MANAGEMENT SYSTEMS ON
SOIL FERTILITY AND PRODUCTION
Refertilization Through Feces and Urine.2-Much of the fer-
tilizer applied to pastures and taken up by the herbage is
eventually returned to the pasture as feces and urine. Of the
fertilizer elements, nitrogen is removed in largest quantities
from the pasture as beef or milk protein. The amounts of
phosphorus, calcium and potassium removed by the animals are
small compared to nitrogen. However, all elements returned to
the soil are concentrated in relatively small areas as urine and
feces spots. This has the effect of depleting most of the pas-
ture area of nutrients.
If the pasture is of low fertility and one animal must graze
several acres to obtain sufficient herbage for normal nutrition,
the area of concentration is relatively much smaller than when
several animals can find sufficient food on a single acre. In
these zones of concentration, leaching losses, particularly of
nitrogen and potassium, are greatly accelerated. This, plus
the natural avoidance of these areas by the animals, leads to
general reduction in plant nutrients and soil fertility.
Tables 1 through 4' illustrate some of the major fertilizer
2 The term manure as used includes feces and urine.
3 Selection of data from "Farm Manure" by R. M. Salter and C. J. Schol-
lenberger, Ohio Agr. Exp. Sta. Bul. 605. September 1939.





















TABLE 1.-MAJOR ELEMENT FERTILIZER VALUE OF CATTLE EXCREMENT.


Daily Production Composition of Fresh Excrement in Percent
Per Animal, Nitrogen Phosphorus Potassium Lime
in Pounds Dry Matter (N) (P205) (K20) (CaO)
feces urine feces | urine feces urine feces urine feces urine feces urine


52 20 16.2 6.2 .32 .95


.21 .03


.16 .95


.34 .01







Maintaining Fertility Under Permanent Pasture 19

factors to be considered in cattle excrement. In Table 1 the
high nitrogen and potassium content of manure is clearly il-
lustrated; Table 2 shows the high percentages of nitrogen,
potassium and phosphorus that are taken in as feed and re-
turned as manure. More minerals are retained in young, grow-
ing animals and lactating cows than by fully grown steers. The
quantities of these elements present in the feed will also affect
the percentage retained.
TABLE 2.-PERCENTAGES OF MAJOR ELEMENTS IN FEED RECOVERED IN
CATTLE EXCREMENT.

Nitrogen Phosphorus Potassium

Range of percent ........ 66-96 33-93 73-99
Average percent ........... 73 79 87

Table 3 gives the relative distribution of these elements in
feces and urine.
TABLE 3.-PERCENTAGE DISTRIBUTION OF MAJOR ELEMENTS IN FECES
AND URINE.

| Nitrogen | Phosphorus Potassium

Feces ..-........................-.. 60 98 22
Urine .................-............ 40 2 78


Table 4 shows the losses into the air, primarily by simple
volatilization of ammoniacal forms of nitrogen when excre-
ments are exposed to drying. These conditions are not as se-
vere as those encountered in Florida during most of the year,
so it may well be assumed that Florida losses would be even
higher than those shown in the table.
TABLE 4.-PERCENTAGE NITROGEN LOSSES INTO AIR WHEN CATTLE
EXCREMENT IS EXPOSED TO DRYING AT 680F.

Time Ammonia Nitrogen Total Nitrogen
Still air Moving air* Still air Moving air*

12 hours .... 15.2 49.4 7.7 25.1
7 days ....-. 71.3 73.5 36.2 37.3

8/-mile wind.
Under average conditions the animal will retain about one-
fourth of the nitrogen taken in as feed; one-fourth will be lost
in the air through rapid volatilization; and one-half may be







Florida Agricultural Experiment Stations


concentrated in small areas and subject to leaching losses be-
fore it re-enters the grass and resumes the feed cycle. Since
nitrogen is so important to animal growth and can be lost at
so many points in the soil-forage-animal cycle, it is usually the
critical element in maintaining pasture production.
Under conditions of high fertility and heavy grazing drag-
ging the pasture to scatter the feces will distribute returned
plant nutrients more evenly. This will help maintain general
soil fertility. Such an operation probably would not be profitable
on low-fertility pastures.
Feces and urine spots serve as indicators of the general fer-
tility of a pasture just as surely as a soil test. If the color of
herbage growing in these spots is similar to that of the rest
of the pasture, the general soil fertility is probably high and
no fertilizer is needed. On the other hand if the herbage is
darker green in these spots, it is a clear indication that soil
fertility is low. An application of fertilizer must be made if
maximum production in the pasture is to be obtained.
A plot of land does not become more fertile just because it
is grazed by animals. Actually, it becomes poorer as the ani-
mals gain and remove the minerals. Pasture soils can become
more fertile only if they are fertilized enough so that there is
an increase in soil organic matter and plant nutrients. The
more organic matter in the soil, the more plant nutrients the
soil can hold against leaching, and, therefore, the more plant
growth the soil can support.
Organic matter in Florida soils is like money in the bank-
it takes years under proper management and fertilization to
increase it and only a short period of over-grazing and inade-
quate fertilization to exhaust it. Yet it does constitute a real
reserve. It can be called upon to help carry a pasture through
a fairly productive season if a fertilizer shortage or economic
stress should interrupt the normal fertilizer program.
Cutting for Hay or Silage.-The possibilities of making good
hay crops for supplementary winter feeding are expanding con-
siderably as more hay drying facilities become available. A
hay or silage crop takes more nutrients from pasture soils than
over-grazing, since under these conditions not even the manure
is returned to the soil. When a hay crop is cut, the plant
nutrients removed must be replaced.
One ton of average quality Pangola hay will contain as much
as 20 pounds of nitrogen, 20 pounds of potassium, 4 pounds of







Mintatining Fertility Under Permanent Pasture


phosphorus, 20 pounds of calcium, 6 pounds of magnesium and
smaller amounts of the minor elements. It is difficult to de-
termine just how much phosphate fertilizer would be necessary
to supply the phosphorus in this hay because much of the phos-
phate becomes insoluble in the soil. Nitrogen and potassium
are recovered nearly quantitatively in pasture herbage; thus
it would take over 300 pounds of a 6-6-6 fertilizer to replace
the nitrogen and potassium removed from the soil by one ton
of hay. It is not surprising that many pastures that have
yielded a heavy tonnage of hay fail to produce satisfactory
herbage after such a cutting when they are not properly re-
fertilized. The limited nutrients in Florida soils must be re-
placed and supplemented if satisfactory yields are to be obtained.

FERTILITY MAINTENANCE PROGRAMS FOR SOILS
UNDER PASTURES
Establishment.-In establishing new pastures, be sure to
select pasture plants adapted to existing soil conditions. The
soil should be tested to determine the lime requirement to bring
the soil pH within the optimum range for growth of the plants
selected. Every effort should be made to prepare and fertilize
the soil and to plant in accordance with standard recommenda-
tions for establishment of pastures (2, 5, 10).
Fertilizer recommendations for the establishment of grass
pastures vary considerably. Large applications of fertilizers
are not necessary on newly seeded or sprigged grasses, as young
plants do not use nutrients rapidly. Since there are few soils
in Florida which will furnish adequate quantities of nutrients
for newly planted pastures, some fertilizer should be applied
before or at planting. A frequent cause for failure of a stand
to develop is inadequate nutrients for the young plants.
It is desirable to plant perennial grasses which are seeded,
such as the Bahias, in February or March in order that a sod
may be formed for the following year. Since these grasses
grow relatively slowly and may be held back by dry weather
in the spring, an application of 300 pounds per acre of 5-7-5
at seeding time is adequate. When the rainy season begins
additional fertilizer should be applied. The use of 300 pounds
per acre of a complete fertilizer such as 5-7-5 or 6-6-6 is recom-
mended, since most new areas are deficient in all the major
plant nutrients.
Additional nitrogen and potash applied as 10-0-10 at 200







Mintatining Fertility Under Permanent Pasture


phosphorus, 20 pounds of calcium, 6 pounds of magnesium and
smaller amounts of the minor elements. It is difficult to de-
termine just how much phosphate fertilizer would be necessary
to supply the phosphorus in this hay because much of the phos-
phate becomes insoluble in the soil. Nitrogen and potassium
are recovered nearly quantitatively in pasture herbage; thus
it would take over 300 pounds of a 6-6-6 fertilizer to replace
the nitrogen and potassium removed from the soil by one ton
of hay. It is not surprising that many pastures that have
yielded a heavy tonnage of hay fail to produce satisfactory
herbage after such a cutting when they are not properly re-
fertilized. The limited nutrients in Florida soils must be re-
placed and supplemented if satisfactory yields are to be obtained.

FERTILITY MAINTENANCE PROGRAMS FOR SOILS
UNDER PASTURES
Establishment.-In establishing new pastures, be sure to
select pasture plants adapted to existing soil conditions. The
soil should be tested to determine the lime requirement to bring
the soil pH within the optimum range for growth of the plants
selected. Every effort should be made to prepare and fertilize
the soil and to plant in accordance with standard recommenda-
tions for establishment of pastures (2, 5, 10).
Fertilizer recommendations for the establishment of grass
pastures vary considerably. Large applications of fertilizers
are not necessary on newly seeded or sprigged grasses, as young
plants do not use nutrients rapidly. Since there are few soils
in Florida which will furnish adequate quantities of nutrients
for newly planted pastures, some fertilizer should be applied
before or at planting. A frequent cause for failure of a stand
to develop is inadequate nutrients for the young plants.
It is desirable to plant perennial grasses which are seeded,
such as the Bahias, in February or March in order that a sod
may be formed for the following year. Since these grasses
grow relatively slowly and may be held back by dry weather
in the spring, an application of 300 pounds per acre of 5-7-5
at seeding time is adequate. When the rainy season begins
additional fertilizer should be applied. The use of 300 pounds
per acre of a complete fertilizer such as 5-7-5 or 6-6-6 is recom-
mended, since most new areas are deficient in all the major
plant nutrients.
Additional nitrogen and potash applied as 10-0-10 at 200







22 Florida Agricultural Experiment Stations

pounds per acre in the fall will increase growth and raise the
nutritional level of the plants. This will help prevent winter-
killing. The plants also will be in a better condition to begin
vigorous growth the following spring.

Fig. 2.-Proper fertilization speeds establishment. A Pangola grass
pasture on Leon fine sand ready for heavy grazing only two months after
planting.









Rmil j







Maintaining Fertility Under Permanent Pasture


Vegetatively planted grasses, such as Pangola and the Bermu-
das, are best planted when moisture becomes available in late
June or July. Three hundred pounds per acre of 5-7-5 fertilizer
or similar analysis should be applied at sprigging time (Fig.
2). Three to five hundred pounds of a 5-7-5 or 6-6-6 mixture
should be applied about September 15 to stimulate the grass for
late fall growth and to condition it for better growth the follow-
ing spring. If economy of fertilization is not as important as
very rapid establishment, additional fertilizer-200 to 400
pounds per acre of 10-0-10 or similar analysis-may be added
in early August.
In the southern half of peninsular Florida the planting dates
for both vegetatively and seed-planted grasses are more de-
pendent on favorable moisture relations than season. Some
changes in the suggested fertilization schedule may be neces-
sary for most favorable results with grasses planted in this
area at other seasons.
Pangola grass makes better growth, particularly on newly
planted flatwoods areas, when copper and other minor elements
are included in the fertilization program. Other highly pro-
ductive grasses may respond similarly. Information previously
discussed should be considered before using minor elements.
The advice of the County Agricultural Agent frequently will be
helpful.
There are clovers available which are adapted to many pasture
areas in Florida. White clover makes excellent growth on moist
flatwoods soils. Hubam or other annual sweet clovers make
good growth on higher, drier soils. Since clovers generally
make their best growth at the time of the year when the grasses
are growing slowly, or not at all, and since clovers do not re-
quire nitrogen in their fertilization program, it is not generally
economical to have pure grass pastures where clovers thrive.
Clovers should be grown in combination with grasses except
when soil conditions do not permit or where grasses are heavily
fertilized in the fall and left standing for winter feed. In this
case clovers cannot be successfully grown because of excessive
shading by the grass.
When clovers are to be grown with grasses, the grass is
generally planted in the spring or summer and the clovers are
seeded in the fall, preferably in October. To insure a stand of







Florida Agricultural Experiment Stations


clovers it is desirable to disk, clip, or graze the sod sufficiently
to reduce competition from the grass. Clover seed should be
well inoculated with the proper organism at two to four times
the manufacturer's recommended rate. This will insure good
nitrogen fixation in the young clover. It may be seeded broad-
cast or with a seeder attachment on a cultipacker. If the seed
is broadcast, use some means to cover the seed and compact the
soil to decrease drying, protect the inoculating organisms and
reduce loss of seedlings.
There are two major divisions of mineral soils of Florida,
which have already been discussed. They must be considered
separately in establishing pastures, particularly clover-grass
combinations. The flatwoods soils and light ridge soils, ex-
cept for certain phosphatic soils, are lacking in phosphorus.
With proper liming these soils will retain applied phosphorus,
and by repeated fertilization a phosphorus reserve will be built
up.
On the other hand, the heavier red and yellow West Florida
soils which contain relatively large quantities of iron and alum-
inum hold large quantities of phosphorus in forms which are
only slowly available to plants. Liming these soils to pH 6.0
or higher will increase availability of phosphorus. The lime
should be added and worked into the soil in advance of phos-
phate fertilization to permit some reaction between the soil
and limestone particles. Even with proper liming, more phos-
phorus must be applied to these soils than to the lighter non-
phosphate-fixing soils to provide adequate quantities for plants.
Newly sodded soil areas with a history of little or no previous
fertilization which are to be seeded to clover should receive
400 to 500 pounds per acre of an 0-10-10, 0-12-12 or 0-14-10
fertilizer at seeding time as a minimum application. More fer-
tilizer may be used on the better soils, but it should be used as
a split application at a later date-December or January.
On the sandy flatwoods and ridge soils this fertilizer ratio
should be changed, after the first year, to one containing a
larger amount of potash relative to phosphate, an 0-10-20, as
will be discussed later. On the heavier soils of western Florida
it is beneficial to continue making annual applications of fer-
tilizer with the high phosphate-potash ratio, 0-14-10, for as
long as three or four years after the initial clover planting.
The phosphate may then be reduced and an 0-10-20 or similar
fertilizer analysis used.







Maintaining Fertility Under Permanent Pasture


Nitrogen applications have not been shown to be of sufficient
value under Florida conditions to warrant including nitrogen in
clover fertilizers. Experiments with nitrogen on clover planted
in a grass sod indicate that in some cases the nitrogen may be
detrimental. A small amount of nitrogen is recommended in
mixed fertilizers for clovers in some states, and analyses such
as 3-12-12, 4-12-12 or 2-14-10 are often found. However, Flor-
ida's mild weather during the fall allows the grass to continue
growth, giving competition for nitrogen and other plant nutri-
ents. The additional growth of the grass also shades the young
clover plants, causing them to be seriously retarded.
If the clover is planted alone on freshly prepared soil, nitro-
gen does stimulate the young clover plants after germination
and before they have nodulated sufficiently to supply their own
nitrogen. This stimulation does not appear to be sufficient to
warrant the additional expense of the nitrogen. Under Florida
conditions nitrogen would be recommended only on new clover
stands a month or six weeks after planting, when it is determ-
ined that a poor inoculation has been obtained. In such cases
a nitrogen application would be necessary to stimulate the
clover until it is well established and becomes inoculated by
natural means-such as the movement of cattle over the area.
Grass Fertilization.-The program outlined in Table 5 is not
necessarily a fixed schedule of fertilizer applications or anal-
yses. It does represent a plan that can be followed on a well
established grass pasture. It is assumed that the soil pH has
been properly adjusted with lime, provision for minor element
fertilization has been made, and that the pasture was fertilized
during establishment in accordance with recommended rates.
It is further assumed that the grass in the pasture is one that
has a high capability of response to fertilizer, such as Pangola,
Pensacola Bahia or the Bermudas.

TABLE 5.-SUGGESTED FERTILIZER REQUIREMENTS FOR ANNUAL
MAINTENANCE OF ESTABLISHED GRASS PASTURE.
SI Rate in Lbs./Acre
Approximate Date Fertilizer* Minimum Maximum

February 15 to April 15...... 6-6-6 500 1,000
July 1-15 ..................-....- 20-0-10 0 200
August 1-15 ....... ............... 33-0-0 0 150
September 15 ................... .. 20-0-10 0 250

SAnalyses represent estimated nutrient requirements; these may not be cur-
rently available fertilizer analyses.







Florida Agricultural Experiment Stations


Under these conditions the minimum rate of fertilization of
500 pounds per acre annually with rotational grazing should be
sufficient to maintain the grass against encroachment of native
vegetation. Under this grazing system an annual beef gain
of about 150 pounds per acre could be expected. Under the
minimum rate the nitrogen and potassium supplied would be
largely expended by July. Sufficient phosphorus is supplied to
cover the normal surface soil losses of one year.
FJertilization at the maximum rate should be used only where
soil moisture and textural conditions favor maximum grass
growth. Space extra applications of nitrogen and potassium
so as to reduce luxury consumption and excessive leaching of
these elements. During some seasons, when moisture condi-
tions and growing temperatures remain favorable in peninsular
Florida, additional fertilization with a 20-0-10 mixture at 150
pounds per acre about November 1 would be desirable.
Fertilizers should normally be applied just after the cattle
have been removed following a grazing period. If appreciable
quantities of mature forage remain at this time, the pasture
should be mowed. Dragging the pasture at the time of fertiliza-
tion gives a better distribution -of the feces.
More frequent applications of smaller amounts of fertilizer
will improve the efficiency of the fertilizer, but the cost of
additional spreading operations reduces the economic value of

Fig. 3.-Well fertilized grass produces more beef per acre. These
grade cows are on Pensacola Bahia grass pasture. (See also cover pic-
ture.)







Maintaining Fertility Under Permanent Pasture


such a practice. Limited experiments in actual beef production
at the Range Cattle Station, as well as estimated gains based
on forage yields from heavily fertilized grass plots in other
parts of Florida, suggest that the total beef gain from the
heavily fertilized pasture may be between 800 and 1,000 pounds
per acre per year if properly managed (Fig. 3).
The problem of using forage produced during the warm, moist
summer months is not solved by this program. Individual grow-
ers will have to solve this according to their needs by cutting
hay or intensively grazing smaller areas during the summer.
However, this does provide a means of maintaining high quality
feed and continuing gains during the late summer and fall-a
period when the soil nitrogen is usually so low that cattle fail
to gain because of the low protein content of the grass, despite
its relatively greater abundance.
Intermediate rates of fertilization will result in intermediate
yields and beef gains, if soil and moisture conditions are equiva-
lent to those of the higher fertilization rate. Intermediate rates
of fertilization are recommended for soils with poorer moisture
relationships and pasture grasses less responsive to fertilizer.
It is strongly recommended that any pasture fertilization at
rates higher than the minimum be done on a split application
basis to reduce leaching losses, to reduce luxury consumption
by the grass, and to produce maximum economic yields from
the fertilizer applied. In this connection, when fertilizing at
the maximum rate, two 500 pound applications of 6-6-6, Febru-
ary 15 and April 15, may prove to be an economic procedure.
Legume-Grass Fertilization.-The use of legumes in the pas-
ture program is a recommended practice wherever they can be
grown successfully. The ideal pasture would be one that pro-
duced a good growth of legumes the year around, since the ni-
trogen portion of the fertilizer could then be eliminated. How-
ever, no entirely satisfactory method of doing this under most
Florida conditions has yet been worked out.
Clovers that will grow in the winter and early spring are
the most popular legumes for Florida pastures, because they
grow during a period when the grass growth is very slow.
They are usually grown in conjunction with grasses. The grass
should be mowed or grazed short about October first, so that
the clover can start without being too heavily shaded. Then,
as the clovers die in late spring, the grass again takes over the
pasture.







Florida Agricultural Experiment Stations


The schedule in Table 6, as in Table 5 for the all-grass pas-
tures, is intended to show the possible range of fertilization and
the approximate fertilizer analyses that could be applied for
post efficient production in terms of maximum quality of feed.
Vhis schedule is made with the assumption that the soil has
been limed to the proper pH range and fertilizer applications
for establishment made in accordance with current recommenda-
tions.
TABLE 6.-SUGGESTED FERTILIZER REQUIREMENTS FOR MAINTENANCE OF
ESTABLISHED CLOVER-GRASS PASTURES.
Rate in Lbs./Acre
Approximate Date Fertilizer* Minimum Maximum
October 15 .....------...-.. .. 0-10-20 500 1,000
February 15 ......................... 0-0-50 0 150
July 15 .................................. 20-0-10 0 200
August 15 ............................. 33-0-0 0 150

Analyses represent estimated nutrient requirements. These may not be cur-
rently available fertilizer formulas.

Clovers have a higher phosphate requirement than grasses
and also require additional sulfur (present as gypsum in super-
phosphate), hence the minimum phosphate for clover-grass
pastures is higher. Clovers also have a higher potassium re-
quirement; this must be met by a higher potash level of fer-
tilization. Under normal Florida conditions grasses exhaust the
potash reserve in the soil to a point about 40 pounds per acre
lower than the minimum required for clover-hence at the end
of the grass season it is necessary to add 40 pounds of potash
to make up this difference before one can really begin to feed
the clover plant. In adding a minimum of 100 pounds of potash
we are making available only about 60 pounds for the growth of
clover. This is enough to produce a little over one ton per acre
of clover hay.
If the maximum rate of 0-10-20 (Table 6) is to be used, it
may be well to use a split application. Apply 500 pounds per
acre about October 15 and another 500 pounds between Decem-
ber 15 and January 15, depending on the season and rate of
growth of the clover The split application will cost more to
apply, but occasionally a heavy rain in late fall will cause heavy
leaching of the potassium. The late application will provide
plant nutrients at a time after the young clover plants are well
established and in condition to utilize them. Even with this
split application, additional potassium is recommended in Feb-







Maintaining Fertility Under Permanent Pasture


ruary or March. This application should be made after the first
heavy grazing of the clover. At this time much of the earlier
applications of potassium have been used by the plants and sub-
sequently concentrated in small areas of urine and feces by the
cattle.
By mid-July the available nitrogen supply in the soil, even in
clover-grass pastures, may be too low to provide a good quality
(high protein) grass. When high quality feed is desired to
continue cattle gains during the late summer and fall, addi-
tional nitrogen fertilizer is necessary, and the pasture should be
treated in a manner similar to all-grass pastures. Early fall
fertilization with nitrgen should be avoided unless it is planned
to harvest a hay crop or graze intensively; because a heavy
growth of grass will smother the seedling clover that usually
germinates in October and November.
The summer legumes, hairy indigo and the lespedezas, have
an important place in the pasture program. These plants can
supply the high-protein feed necessary for gains during the
summer months without the necessity of heavy rates of nitro-
gen fertilizer. Data on the fertilizer requirements of these
plants under Florida conditions are not extensive. On the
basis of the generally high potassium requirement of legumes
and the degree to which potassium may be lost through leach-
ing during the summer months, it is probable that summer
legumes have not been adequately fertilized with potassium.
The use of 0-10-20 at seeding and subsequent top-dressing with
muriate of potash every 30 to 50 days during the grazing period
in a manner similar to the winter clover program may increase
the growth and productivity of these legumes.
Irrigated pastures are being used on a limited scale primarily
to produce supplementary winter feed. Usually the cost of the
water for irrigation is the primary consideration; fertilization
costs are a relatively small part of the total expense. Conse-
quently, such pastures should be fertilized heavily for maximum
production. Pending completion of current experiments, it is
suggested that a fertilization program for clover-grass pastures
under irrigation be similar to that recommended as maximum
in Table 6, with the exception that potassium be applied every
30 to 60 days during the winter clover grazing season.
Irrigation has more than doubled the clover grazing season
and on the heavier textured, damp soils of West Florida, Ladino
clover with irrigation may furnish 12 months of legume graz-







Maintaining Fertility Under Permanent Pasture


ruary or March. This application should be made after the first
heavy grazing of the clover. At this time much of the earlier
applications of potassium have been used by the plants and sub-
sequently concentrated in small areas of urine and feces by the
cattle.
By mid-July the available nitrogen supply in the soil, even in
clover-grass pastures, may be too low to provide a good quality
(high protein) grass. When high quality feed is desired to
continue cattle gains during the late summer and fall, addi-
tional nitrogen fertilizer is necessary, and the pasture should be
treated in a manner similar to all-grass pastures. Early fall
fertilization with nitrgen should be avoided unless it is planned
to harvest a hay crop or graze intensively; because a heavy
growth of grass will smother the seedling clover that usually
germinates in October and November.
The summer legumes, hairy indigo and the lespedezas, have
an important place in the pasture program. These plants can
supply the high-protein feed necessary for gains during the
summer months without the necessity of heavy rates of nitro-
gen fertilizer. Data on the fertilizer requirements of these
plants under Florida conditions are not extensive. On the
basis of the generally high potassium requirement of legumes
and the degree to which potassium may be lost through leach-
ing during the summer months, it is probable that summer
legumes have not been adequately fertilized with potassium.
The use of 0-10-20 at seeding and subsequent top-dressing with
muriate of potash every 30 to 50 days during the grazing period
in a manner similar to the winter clover program may increase
the growth and productivity of these legumes.
Irrigated pastures are being used on a limited scale primarily
to produce supplementary winter feed. Usually the cost of the
water for irrigation is the primary consideration; fertilization
costs are a relatively small part of the total expense. Conse-
quently, such pastures should be fertilized heavily for maximum
production. Pending completion of current experiments, it is
suggested that a fertilization program for clover-grass pastures
under irrigation be similar to that recommended as maximum
in Table 6, with the exception that potassium be applied every
30 to 60 days during the winter clover grazing season.
Irrigation has more than doubled the clover grazing season
and on the heavier textured, damp soils of West Florida, Ladino
clover with irrigation may furnish 12 months of legume graz-







Florida Agricultural Experiment Stations


ing. All-grass pastures under irrigation should probably be
fertilized in a manner similar to the maximum of Table 5, ex-
cept the 6-6-6 could be a fall application and a nitrogen fer-
tilizer should be added every 30 days at about 40 pounds of
nitrogen for every ton, or ton and a half, of dry weight of herb-
age or its equivalent produced.

SUMMARY
It is realized that the maximum rates suggested here are not
in general use in Florida. The authors have observed some
instances where fertilizer quantities in excess of these amounts
have been used, but these lacked proper balance for maximum
yields. In many cases excessive rates at a single application
have failed, as would be expected, to give the return anticipated.
To conserve fertilizer materials and obtain the most for the
fertilizer dollar, it would be well to keep in mind the high solu-
bility of potassium and nitrogen in Florida soils, and plan to
use this information in developing an efficient pasture fertilizer
program.
Florida cattlemen accustomed to grazing their cattle at rates
of one animal to 25 acres may be shocked at the idea of putting
as much fertilizer on a pasture as might be used for some vege-
table crops. However, thousands of acres of improved pastures
are producing only a fraction of the beef per acre that would
be possible by proper use of additional fertilizer.
It is unwise to try a maximum fertility program on a large
scale until the grower has had sufficient experience to know
that he can efficiently utilize the quantity and quality of feed
produced. A few acres of soil with good moisture relation-
ships, heavily fertilized to produce a few grass-fat steers, is
suggested as a beginning approach to a high fertility soil-
pasture program. When yields increase directly in proportion
to the quantity of fertilizer used, it is usually more profitable
to increase the per-acre production of the soil than to increase
the number of acres in production. Florida's temperatures,
rainfall and soil textures are ideal for heavy growth on pas-
tures, provided the fertilizers are supplied and used wisely to
make the pastures produce.








Maintaining Fertility Under Permanent Pasture


OTHER FLORIDA PUBLICATIONS RELATED TO
PASTURES

1. GAMMON, NATHAN, JR., H. W. LUNDY, J. R. NELLER and R. A. CARRI-
GAN. First-year yields from Louisiana White clover-Dallis grass
pasture plots on Carnegie and Tifton fine sandy loams. Fla. Agr.
Exp. Sta. Cir. S-19. 1950.

2. GLASSCOCK, R. S., T. J. CUNHA and A. M. PEARSON. Preliminary ob-
servations on the comparative value of roughages for maintenance
and growth of beef cattle. Fla. Agr. Exp. Sta. Cir. S-9. 1950.

3. HODGES, E. M., D. W. JONES and W. G. KIRK. Grass pastures in cen-
tral Florida. Fla. Agr. Exp. Sta. Bul. 484. 1951.

4. JONES, D. W., E. M. HODGES and W. G. KIRK. Costs and methods of
pasture establishment and maintenance. Fla. Agr. Exp. Sta. Cir.
S-33. 1951.

5. KILLINGER, G. B., and G. E. RITCHEY. Floranna sweet clover and its
culture. Fla. Agr. Exp. Sta. Cir. S-46. 1952.

6. NELLER, J. R., D. W. JONES, NATHAN GAMMON, JR. and R. B. FORBES.
Leaching of fertilizer phosphorus in acid sandy soils as affected
by lime. Fla. Agr. Exp. Sta. Cir. S-32. 1951.

7. NELLER, J. R., G. B. KILLINGER, D. W. JONES, R. W. BLEDSOE, and H. W.
LUNDY. Fertilizer should contain a source of sulfur for pasture in
many areas of Florida. Fla. Agr. Exp. Sta. Cir. S-35. 1951.

8. PARVIN, F. W. Farm enterprises for Florida. I. Increase your farm
income with beef calves. Fla. Agr. Ext. Serv. Cir. 95. 1950.

9. SMITH, F. B., and G. D. THORNTON. Soil testing. Fla. Agr. Exp.
Sta. Press Bul. 617. 1945.

10. VOLK, G. M. Know your fertilizers. Fla. Agr. Exp. Sta. Bul. 506.
1952.

11. VOLK, G. M., and NATHAN GAMMON, JR. Soil reaction (pH). Fla.
Agr. Exp. Sta. Cir. S-39. 1951.




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