C
FERTILIZING FARM FISH PONDS
Leaflet 88
June 1975
AGRICULTURAL EXPERIMENT STATION/AUBURN UNIVERSITY
R. Dennis Rouse, Director Auburn, Alabama
CONTENTS
INTRODUCTION ---- - - - - - - --- - - - - - - -- .3
A SIMPLIFIED FERTILIZATION PROGRAM 3
SUGGESTIONS FOR INCREASING EFFICIENCY 3
New Ponds 4
Old Ponds 4
Muddy Waters- 4
Excess Flow 5
W e e d s .. ...........................................5
L im in g ----- --- ------------- -------------------------- 5
Fertile W atersheds ........ ....... ............... -- 5
Catfish Ponds with Supplemental Feeding............... 5
Catfish Ponds Without Feeding 5
LITERATURE CITED - - 6
[2]
FERTILIZING FARM FISH PONDS
CLAUDE E. BOYD and JACK R. SNOW*
F[SH POND OWNERS in Alabama have
usually found fertilization to be a good
investment. Fertilizer nutrients increase
the production of microscopic plants
(phytoplankton) which in turn serve as
food for microscopic animals (zooplank-
ton) and aquatic insects. Heavy growths
of these microorganisms are called "plank-
ton blooms." Plankton and insects serve
as food for bream, which in turn serve
as the primary food of bass. Proper
use of fertilizer in most Alabama ponds
will increase fish production by four or
five times (7,8). Fish in fertilized ponds
are easier to catch because they are more
abundant and because the abundant
plankton limits their vision causing them
to be less wary (6). Plankton also shades
pond bottoms preventing growth of trou-
blesome rooted weeds and filamentous
algae. (5).
A SIMPLIFIED FERTILIZATION
PROGRAM
A plankton bloom dense enough to
restrict vertical underwater visibility to
12 to 24 inches is adequate for weed
control and good fish production. Plank-
ton turbidity should be established in
late winter or early spring and main-
tained throughout the growing season
(8). The effect of a fertilizer application
usually lasts for about 1 month, and if
not repeated, plankton abundance di-
minishes. Fertilizer can be broadcast
over shallow water areas of ponds, but
* Associate Professors, Department of
Fisheries and Allied Aquacultures.
more efficient use results from placing it
on underwater platforms (2), shown in
the figure. Platforms should be 1 to 2
feet underwater and one platform is ade-
quate for 5 to 10 acres. Fertilizer is
poured onto the platform and wave ac-
tion distributes the soluble nutrients.
Techniques for analyzing pond muds
and waters to accurately determine ferti-
lizer application rates have not been de-
veloped. However, the simplified pro-
cedure outlined below is widely used
and suitable for most ponds.
(1) In mid-February or early March
apply 40 pounds per acre of 20-20-5
fertilizer. Follow with two additional
applications at 2-week intervals.
(2) Make three more applications of
40 pounds per acre of 20-20-5 at 3-week
intervals.
(3) Continue applications of 40
pounds per acre of 20-20-5 at monthly
intervals or whenever the water clears
so that a piece of white metal attached
to a yardstick is visible to a depth of
18 inches.
(4) Discontinue applications for cur-
rent year by last week in October.
SUGGESTIONS FOR INCREASING
EFFICIENCY
Some ponds will not respond, without
remedial preparation, to the simplified
fertilization program outlined above. In
other ponds, use of the simplified pro-
gram will result in wasteful overfertiliza-
tion. Information presented below will
[81
FIG. A fertilizer platform.
be useful in developing the most efficient
method for fertilizing a pond.
New Ponds
Test bottom soils for lime require-
ment, and if necessary, lime before the
pond is filled (1). The simplified fertiliza-
tion program is suitable for most new
ponds, but a 5-20-5 fertilizer may be
used on a trial basis. If adequate phy-
toplankton growth is not obtained, use
20-20-5 fertilization. Although the more
expensive 20-20-5 fertilizer is sold as a
fish pond fertilizer, it was no more ef-
fective than 5-20-5 fertilizer in recent
preliminary experiments at the Fisheries
Research Unit of the Auburn University
Agricultural Experiment Station.
Old Ponds
Pond muds and waters contain organ-
isms which assimilate elemental nitrogen,
nitrate, or ammonia into protein (3). As
ponds age, remains of these organisms
accumulate in bottom muds and upon
decay release inorganic nitrogen. Plank-
ton production is low in unfertilized
ponds, little organic matter accumulates
in muds, and the amount of inorganic
nitrogen released upon decay is inade-
quate to support abundant phytoplank-
ton growth. 
More organic 
matter ac-
cumulates in muds of fertilized ponds
and after about 5 years the rate of re-
lease of inorganic nitrogen is adequate
to support dense plankton growth (9).
Potassium also accumulates in waters
and soils of fertilized ponds and within
a few years additions of this nutrient are
usually no longer required (9). Therefore,
an old pond with no history of fertiliza-
tion should be fertilized in the same
manner as a new pond. In an old pond
with a history of fertilization, apply 40
pounds of superphosphate or 18 pounds
of triple superphosphate per acre per
application. A plankton bloom may not
develop quickly in the spring in some
ponds which receive only phosphate
fertilizer. In such situations, apply a
fertilizer containing nitrogen and phos-
phate until a satisfactory bloom develops
and then continue with phosphate - only
fertilization. The nitrogen supply in
ponds receiving phosphate - only ferti-
lization is maintained by nitrogen fixing
algae and bacteria which abound in fer-
tile waters (3,9).
Muddy Waters
Ponds with muddy water in which
underwater visibility is less than 12
inches cannot respond to added nutri-
ents because of insufficient light penetra-
[4]
tion for phytoplankton growth. Two or
three applications of barnyard manure
at the rate of 1 ton per acre.per appli-
cation at 3-week intervals will normally
clear water so that fertilization 
will be
effective (8). The use of 75 pounds 
of
cottonseed meal and 25 pounds of super-
phosphate per acre at 2-to-3-week inter-
vals will also clear muddy water (8).
However, such procedures are ineffective
if ponds receive large amounts of muddy
runoff water after each rain. Unless ero-
sion of the watershed is prevented by
revegetation or the muddy runoff di-
verted, fertilization is not advisable.
Excess Flow
The detention or resident time of
water in a pond must exceed 3 to 4
weeks, otherwise fertilizer nutrients are
flushed out of the pond before they can
be used to produce fish food. Methods
for increasing detention time of water
include; diversion of excess water, en-
largement of pond, and construction of
another pond above the existing pond.
Some ponds have excess flow only dur-
ing winter and spring and may respond
to fertilization during dry weather.
Weeds
Weed control must be effected in
ponds which are choked with weeds,
otherwise fertilizer nutrients will stimu-
late weeds rather than phytoplankton.
Applications of fertilizer in late winter
and early spring to weed infested ponds
will produce filamentous algae which
grow over and smother weeds. The fila-
mentous algae will normally be replaced
by plankton in warm weather (5). Chemi-
cal weed control may be necessary in
some ponds.
Liming
Ponds with waters softer than 20 mil-
ligrams per liter total hardness or alka-
linity may not respond to fertilization
(1,10). Applications of agricultural lime-
stone to such ponds will neutralize acid-
ity of the mud, and increase total hard-
ness and alkalinity of the water, thereby
increasing the effectiveness of fertilizers
(1). The Auburn University Soil Testing
Laboratory makes lime requirement de-
terminations of muds for pond owners
for a small fee. If a bottom mud analysis
seems desirable, collect muds from dif-
ferent areas of the pond bottom where
water is deeper than 3 feet and mix the
muds to make one sample. An adequate
sample from a 5-acre pond would con-
tain mud from 12 to 15 different areas
of the bottom. Dry the sample and ship
about 1 quart to the laboratory for
analysis. Mailing cartons are available
from county extension chairmen.
If lime is needed, apply agricultural
limestone during winter months in ponds
which are full of water. In new ponds,
the limestone should be applied prior to
filling with water. The limestone should
be spread over the entire pond area.
However, if this is not possible, bene-
ficial results can be obtained by spread-
ing limestone around the shallower water
edges.
Fertile Watersheds
Follow recommendations for old ferti-
lized ponds. Some ponds in well ferti-
lized pastures may require little or no
additional fertilization for satisfactory
fish production.
Catfish Ponds with Supplemental
Feeding
Begin applications of fertilizer in
spring after filling pond. Suspend ferti-
lization when feeding rates reach 10
pounds per acre per day or when tur-
bidity restricts underwater visibility to
18 inches. Usually only.2 or 3 applica-
tions of fertilizer are needed (4).
Catfish Ponds without Feeding
Follow the fertilization procedure rec-
ommended above for bass-bluegill ponds.
[5]
LITERATURE CITED
(1) BOYD, C. E. 1974. Lime requirements
of Alabama fish ponds. Agr. Exp. Sta.,
Auburn Univ., Bull. 459. 20 pp.
(2) LAWRENCE, J. M. 1954. A new method
of applying inorganic fertilizer to farm
fishponds. Progr. Fish-Cult. 16: 176-
178.
(3) MORTIMER, C. H. 1954. Fertilizers 
in
fishponds. Colonial Office. Fisheries
Pub. No. 5. Her Majesty's Stationery
Office. London. 155 pp.
(4) PRATHER, E. E. 1970. Fishing suc-
cess for channel catfish and white cat-
fish in ponds with daily feeding. Proc.
Ann. Conf. SE Assoc. Game and Fish
Comm. 23: 480-490.
(5) SMITH, E. V. AND H. S. SWINGLE. 
1942.
The use of fertilizer for controlling
several submersed aquatic plants in
ponds. Trans. Amer. Fish. Soc. 71:
94-101.
(6) SWINGLE, H. S. 1945. Improvement
of fishing in old ponds. Trans. North
Amer. Wildl. Conf. 10: 299-308.
(7) . 1947. Experiments on
pond fertilization, Agr. Exp. Sta., Ala.
Polytech. Inst., Bull. 264. 36 pp.
(8) SWINGLE, H. S. AND E. V. SMTH. 1947.
Management of farm fish ponds. Agr.
Exp. Sta., Ala. Polytech. Inst., Bull.
254. 32 pp.
(9) , B. C. GoOCH, AND
H. R. RABANAL. 1964. Phosphate ferti-
lization of ponds. Proc. Ann. Conf. SE
Game and Fish Comm. 15: 236-245.
(10) THOMASTON, W. E. AND H. O. ZELLER.
1961. Results of a six-year investiga-
tion of chemical soil and water analysis
and lime treatment in Georgia fish
ponds. Proc. Ann. Conf. SE Game
and Fish Comm. 15: 236-245.
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